2004-2006 Project Fellow in Special Assistance Programme of UGC in Department of Biophysics, Panjab University, Chandigarh, India
2006- 2008 Senior Research Fellow (Indian Council of Medical Research, India) Department of Biophysics, Panjab University, Chandigarh, India
2008-2011 Research Associate, Department of Internal Medicine, School of Medicine, Wayne State University, Detroit, MI, USA
2011-Present Research Fellow, Department of Chemical Engineering, University of Michigan, Ann Arbor, MI, USA
SOCIETY MEMBERSHIPS Associate Member, American Association for Cancer Research, Philadelhia, PA, USA Affiliate Member, National Postdoctoral Association, Washington, DC, USA Core Team Member, Postdoctoral Association, Wayne State University, MI, USA Life Member, Indian Biophysical Society, Saha Institute of Nuclear Physics, Kolkata, India
JOURNAL REVIEWER 2011 Cancer Biology and Therapy 2010 International Journal of Experimental Pathology 2010 American Journal of Bio-Medical Sciences
Abstract: Although microRNA-21 (miR-21) is emerging as an oncogene and has been shown to target several tumor suppressor genes, including programmed cell death 4 (PDCD4), its precise mechanism of action on cancer stem cells (CSCs) is unclear. Herein, we report that FOLFOX-resistant HCT-116 and HT-29 cells that are enriched in CSCs show a 3- to 7-fold upregulation of pre- and mature miR-21 and downregulation of PDCD4. Likewise, overexpression of miR-21 in HCT-116 cells, achieved through stable transfection, led to the downregulation of PDCD4 and transforming growth factor beta receptor 2 (TGFβR2). In contrast, the levels of β-catenin, TCF/LEF activity and the expression of c-Myc, Cyclin-D, which are increased in CSCs, are also augmented in miR-21 overexpressing colon cancer cells, accompanied by an increased sphere forming ability in vitro and tumor formation in SCID mice. Downregulation of TGFβR2 could be attributed to decreased expression of the receptor as evidenced by reduction in the activity of the luciferase gene construct comprising TGFβR2-3' untranslated region (UTR) sequence that binds to miR-21. Moreover, we observed that downregulation of miR-21 enhances luciferase-TGFβR2-3' UTR activity suggesting TGFβR2 as being one of the direct targets of miR-21. Further support is provided by the observation that transfection of TGFβR2 in HCT-116 cells attenuates TCF/LEF luciferase activity, accompanied by decreased expression of β-catenin, c-Myc and Cyclin-D1. Our current data suggest that miR-21 plays an important role in regulating stemness by modulating TGFβR2 signaling in colon cancer cells.
Abstract: One of the most consistent pathological conditions in the gastrointestinal (GI) tract with advancing age is malignancy, particularly GI cancers, the incidence of which increases sharply with aging. Although the reasons for the age-related rise in colorectal cancer are not fully understood, we hypothesize that aging increases susceptibility of the colon to carcinogen(s)/toxicant(s) leading to an increase in cancer stem-like cells (CSLCs) that express cancer stem cell markers, in the colonic mucosa. The current study demonstrates that aging is associated with increased expression of several colon CSLC markers: CD44, CD166 and ALDH-1 and a higher proportion of cells expressing these markers. Aging is also accompanied by increased expression of miR-21 in colon. These increases are further increased in response to the colonic carcinogen dimethylhydrazine (DMH). Aging is also associated with increased tyrosine phosphorylated EGFR in colon and increased co-expression of EGFR and CD166 in the colonic crypts. This co-expression is further enhanced in response to DMH. Inhibition of EGFR using the EGFR inhibitor cetuximab abrogated the age-related increase in CD166 and ALDH-1 as well as miRNA (miR)-21. Our results provide new evidence that aging and DMH are associated with increases in CSLC biomarkers and miR21, each of which have been linked to colorectal cancer. EGFR inhibition attenuates these changes indicating a role for EGFR in age and mutagen associated changes in CSLCS.
Abstract: ABSTRACT: Metastatic colorectal cancer remains a serious health concern with poor patient survival. Although 5-Fluorouracil (5-FU) or 5-FU plus oxaliplatin (FOLFOX) is the standard therapy for colorectal cancer, it has met with limited success. Recurrence of the tumor after chemotherapy could partly be explained by the enrichment of the chemo-resistant sub-population of cancer stem cells (CSCs) that possess the ability for self-renewal and differentiation into different lineages in the tumor. Therefore development of therapeutic strategies that target CSCs for successful treatment of this malignancy is warranted. The current investigation was undertaken to examine the effectiveness of the combination therapy of dasatinib (a Src inhibitor) and curcumin (a dietary agent with pleiotropic effect) in inhibiting the growth and other properties of carcinogenesis of chemo-resistant colon cancer cells that are enriched in CSCs sub-population. Remnants of spontaneous adenomas from APCMin +/- mice treated with dasatinib and/or curcumin were analyzed for several cancer stem cell markers (ALDH, CD44, CD133 and CD166). Human colon cancer cells HCT-116 (p53 wild type; K-ras mutant) and HT-29 (p53 mutant; K-ras wild type) were used to generate FOLFOX resistant (referred to as CR) cells. The effectiveness of the combination therapy in inhibiting growth, invasive potential and stemness was examined in colon cancer CR cells. The residual tumors from APCMin +/- mice treated with dasatinib and/or curcumin showed 80-90% decrease in the expression of the CSC markers ALDH, CD44, CD133, CD166. The colon cancer CR cells showed a higher expression of CSCs markers, cell invasion potential and ability to form colonospheres, compared to the corresponding parental cells. The combination therapy of dasatinib and curcumin demonstrated synergistic interactions in CR HCT-116 and CR HT-29 cells, as determined by Calcusyn analysis. The combinatorial therapy inhibited cellular growth, invasion and colonosphere formation and also reduced CSC population as evidenced by the decreased expression of CSC specific markers: CD133, CD44, CD166 and ALDH. Our data suggest that the combination therapy of dasatinib and curcumin may be a therapeutic strategy for re-emergence of chemo-resistant colon cancer by targeting CSC sub-population.
Abstract: We have previously demonstrated that expression of the novel gene schlafen-3 (Slfn-3) correlates with intestinal epithelial cell differentiation (Patel VB, Yu Y, Das JK, Patel BB, Majumdar AP. Biochem Biophys Res Commun 388: 752-756, 2009). The present investigation was undertaken to examine whether Slfn-3 plays a role in regulating differentiation of FOLFOX-resistant (5-fluorouracil + oxaliplatin) colon cancer cells that are highly enriched in cancer stem cells (CSCs). Transfection of Slfn-3 in FOLFOX-resistant colon cancer HCT-116 cells resulted in increase of alkaline phosphatase activity, a marker of intestinal differentiation. Additionally, Slfn-3 transfection resulted in reduction of mRNA and protein levels of the CSC markers CD44, CD133, CD166, and aldehyde dehydrogenase 1 in both FOLFOX-resistant HCT-116 and HT-29 cells. This was accompanied by decreased formation of tumorosphere/colonosphere (an in vitro model of tumor growth) in stem cell medium and inhibition of expression of the chemotherapeutic drug transporter protein ABCG2. Additionally, Slfn-3 transfection of FOLFOX-resistant HCT-116 and HT-29 cells reduced Hoechst 33342 dye exclusion. Finally, Slfn-3 transfection inhibited the expression of transforming growth factor-α in both FOLFOX-resistant colon cancer cells, but stimulated apoptosis in response to additional FOLFOX treatment. In summary, our data demonstrate that Slfn-3 expression inhibits multiple characteristics of CSC-enriched, FOLFOX-resistant colon cancer cells, including induction of differentiation and reduction in tumorosphere/colonosphere formation, drug transporter activity, and autocrine stimulation of proliferation. Thus Slfn-3 expression may render colon CSCs more susceptible to cancer chemotherapeutics.
Abstract: As our population ages, diseases affecting memory and daily functioning will affect an increasing number of individuals, their families and the healthcare system. Therefore, there is a need to study and evaluate effects of certain conditions for anti-aging of the brain. Nutrient supplementation can modify the brain function. The chemistry and function of both the developing and the mature brain are influenced by diet (Fernstrom, Am J Clinical Nutrition 71:1669S-1673S, 2000). Clinical, biochemical, and pathological aspects have shown a correlation between mental symptoms, especially depression and cognitive decline, with high incidence of folate deficiency (Bottiglieri et al., J Neurol Neurosurg Psychiatry 69:562, 2000). In the present study, consequences of folic acid supplementation on brain dysfunction as a result of aging were studied in cerebral cortex, mid brain, and cerebellar regions of rat brain. This study was carried out on 6-, 11-, and 16-month-old rats, which received folic acid at a dose of 5 mg/kg body weight/day for a period of 8 weeks. Respective control groups of the same age groups were also taken. At the end of the treatment duration, behavioral studies were performed and later the animals were killed for various biochemical and histological investigations. Results indicated significant improvement in memory as assessed by active avoidance, passive avoidance, and plus maze tests in the folic acid supplemented aged animals. Significant improvement was also seen in the cellular protective mechanisms where by the activity of superoxide dismutase and catalase enzymes increased in folic acid supplemented group and so was the glutathione content. Increased lipid peroxidation content, a marker of aging, was also found to be decreased during folic acid supplementation in all the three regions of brain in our study. Thus, it can be concluded that folic acid helps in improving the memory status by reducing oxidative stress and maintaining the integrity of neurons during aging.
Abstract: Recurrence of colon cancer, which affects nearly 50% of patients treated by conventional therapeutics, is thought to be due to re-emergence of chemotherapy-resistant cancer stem/stem-like cells (CSCs). Therefore, development of therapeutic strategies for targeted elimination of CSCs would be a novel strategy. The current study examines whether difluorinated-curcumin (CDF), a novel analog of the dietary ingredient of curcumin, in combination with 5-fluorouracil and oxaliplatin (5-FU + Ox), the mainstay of colon cancer chemotherapeutic, would be effective in eliminating colon CSCs.
Abstract: Abstract Colorectal cancer is the third most common form of malignancy, behind prostate and lung cancers. Despite recent advances in medicine, mortality from colorectal cancer remains high, highlighting the need for improved therapies. Numerous studies have demonstrated increased activation of EGFR and its family members (EGFRs), IGF-1R as well as c-Src in colorectal cancer. The current study was undertaken to examine the effectiveness of combination therapy of dasatinib (BMS-354825; Bristol-Myers Squibb), a highly specific inhibitor of Src family kinases (SFK) and a nontoxic dietary agent; curcumin (diferuloylmethane), in colorectal cancer in in vitro and in vivo experimental models. For the latter, we utilized C57BL/6 APCMin+/− mice. Initial in vitro studies revealed synergistic interactions between the two agents. Additionally, we have observed that combination treatment causes a much greater inhibition of the following metastatic processes than either agent alone: (i) colony formation, (ii) invasion through extracellular matrix and (iii) tubule formation by endothelial cells. Dasatinib affects the cell adhesion phenotype of colon cancer HCT-116 cells whereas the combination therapy enhances this effect to a greater extent. Preclinical investigation revealed that the combination therapy to be highly effective causing an over 95% regression of intestinal adenomas in ApcMin+/− mice, which could be attributed to decreased proliferation and increased apoptosis. In conclusion, our data suggest that combination treatment of dasatinib and curcumin could be a potential therapeutic strategy for colorectal cancer.
Abstract: Recent evidence suggests that epithelial cancers, including colorectal cancer are driven by a small sub-population of self-renewing, multi-potent cells termed cancer stem cells (CSCs) which are thought to be responsible for recurrence of cancer. One of the characteristics of CSCs is their ability to form floating spheroids under anchorage-independent conditions in a serum-free defined media. The current investigation was undertaken to examine the role of Wnt/beta-catenin pathway in regulating the growth and maintenance of colonospheres. Human colon cancer cells HCT-116 (p53 wild type; K-ras mutant), HCT-116 (p53 null; K-ras mutant) and HT-29 (p53 mutant) were used.
Abstract: Cells of the gastrointestinal (GI) mucosa are subject to a constant process of renewal which, in normal adults, reflects a balance between the rates of cell production and cell loss. Detailed knowledge of these events is, therefore, essential for a better understanding of the normal aging processes as well as many GI diseases, particularly malignancy, that represent disorders of tissue growth. In general, many GI dysfunctions, including malignancy, increase with advancing age, and aging itself is associated with alterations in structural and functional integrity of the GI tract. Although the regulatory mechanisms for age-related increase in the incidence of GI-cancers are yet to be fully delineated, recent evidence suggests a role for epidermal growth family receptors and its family members {referred to as EGFR(s)} in the development and progression of carcinogenesis during aging. The present communication discusses the involvement of EGFR(s) in regulating events of GI cancers during advancing age and summarizes the current available therapeutics targeting these receptors. The current review also describes the effectiveness of ErbB inhibitors as well as combination therapies. Additionally, the involvement of GI stem cells in the development of the age-related rise in GI cancers is emphasized.
Abstract: In the past 10 to 15 years, a considerable progress has been made in the treatment of gastrointestinal (GI) related malignancies, as number of agents expanded from only one in 1995 to seven in 2006. Current review describes the recent role of targeted therapies, specifically EGFR inhibitors in the treatment of GI cancers. Importance of dietary agents in the treatment and prevention of GI cancers is also reviewed.
Abstract: 5-Fluorouracil (5-FU) or 5-FU plus oxaliplatin (FOLFOX) remains the backbone of colorectal cancer chemotherapeutics but with limited success. This could partly be due to the enrichment of cancer stem cells (CSCs) that are resistant to conventional chemotherapy. Therefore, validation of a nontoxic agent that can either cause reversal of chemoresistance or promote the killing of CSCs would be highly desirable. The current study examines whether curcumin, the major active ingredient of turmeric, either alone or together with FOLFOX, would be an effective strategy to eliminate colon CSCs. Exposure of colon cancer HCT-116 or HT-29 cells to FOLFOX that inhibited their growth led to the enrichment of CSC phenotype as evidenced by increased proportion of CD133-, CD44-, and/or CD166-positive cells and epidermal growth factor receptor (EGFR) levels. Treatment of FOLFOX-surviving colon cancer cells with either curcumin alone or together with FOLFOX resulted in a marked reduction in CSCs, as evidenced by the decreased expression of CD44 and CD166 as well as EGFR and by their ability to form anchorage-dependent colonies. They also caused disintegration of colonospheres. Increased expression of EGFR in FOLFOX-surviving cells could be attributed to hypomethylation of the EGFR promoter, whereas an opposite phenomenon was observed when the FOLFOX-surviving cells were treated with curcumin and/or FOLFOX. These changes were accompanied by parallel alterations in the levels of DNA methyltransferase 1. In conclusion, our data suggest that curcumin by itself or together with the conventional chemotherapeutic could be an effective treatment strategy for preventing the emergence of chemoresistant colon cancer cells by reducing/eliminating CSCs.
Abstract: Evidence suggests that nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit cycloxygenase (COX) and production of the proinflammatory prostaglandin, PGE2, and thus prevent carcinogenesis in the colon. Indeed, one of the specific COX-2 inhibitors, celecoxib, had been accepted by the US FDA for the treatment of familial adenomatous polyposis. However, the molecular mechanism of such inhibition is not clear, although apoptosis appears to be the dominant antiproliferative end effect. The present study delineates the intracellular ionic milieu in the colonocytes that could generate strong apoptotic signals where DMH-induced carcinogenesis was studied in the initiation stage in rats and its regression with the COX inhibitors. While DMH treatment produced a significant elevation in the Na+/H+ exchanger activity and resultant proton efflux, this was reversed by the NSAIDs, particularly so with celecoxib and etoricoxib compared to aspirin. Similarly, the intracellular pH was changed, with more alkalosis noted in DMH, which was reversed by NSAIDs. Also, an intracellular Ca2+ build up was noted by Fura 2 AM, which was also supported by a reduced Ca2+ ATPase and an enhanced inward movement of Ca2+. Further, mitochondrial dysfunction-related cyt C release, increased DNA ladder formation, activation of caspase-3, and cleavage product of poly (ADP-ribose) polymerase (PARP) were not seen in DMH but well noted in NSAIDs. Our results indicate that NSAIDs can induce apoptosis through a change in the colonic Na+/H+ exchange, intracellular pH, and an unfavorable Ca2+ homeostasis.
Abstract: The present study was designed to investigate the effects of a selective cycloogenase-2 (COX-2) inhibitor, etoricoxib, on the membrane-specific enzymes, lipid composition, and changes in fluidity parameters of rat colonic plasma membrane. Two doses of the drug were used, one within its therapeutic anti-inflammatory range as based on the ED50 value in rats (Eto-1), while the other at 10 times higher dose relating to the toxicity studies (Eto-2), which have not been reported so far. The activity of the membrane alkaline phosphatase was found to be increased after treatment with both the doses of etoricoxib as compared to the control. The total lipid and the cholesterol content showed a decrease while an increase in ganglioside sialic acid content was noted. Phospholipid content and the cholesterol-phospholipid molar ratio showed no change in either of the treatment groups. Fluorescence polarization studies with diphenylhexatriene showed that membrane fluidity was least altered in the isolated brush border membrane from colon or in the liposomes prepared from the membrane lipid extracts. Also, the translational diffusion studied with pyrene showed that the fluidity parameter was decreased as measured by the excimer formation. It is concluded that etoricoxib, a new generation COX-2 inhibitor (called the coxibs), appeared to be a safe nonsteroidal anti-inflammatory drug (NSAID) in the colonic membranes.
Abstract: The present study was designed to evaluate the effects of three non-steroidal anti-inflammatory drugs (NSAIDs) with varying cycloxygenase selectivities on the small intestinal biochemical composition, function and histology during 1, 2-dimethylhydrazine (DMH) administration. Sprague Dawley male rats were divided into five different groups viz: Group 1 (control, vehicle treated), Group 2 (DMH-treated, 30 mg/kg body weight/week in 1 mM EDTA-saline, subcutaneously), Group 3 (DMH + aspirin-60 mg/kg body weight), Group 4 (DMH + celecoxib-6 mg/kg body weight), Group 5 (DMH + etoricoxib-0.64 mg/kg body weight). After six weeks of treatment, brush border membrane was isolated from the jejunum segment of all the groups and changes in the associated enzymes such as sucrase, lactase, maltase, alkaline phosphatase, membrane lipid composition, fluorescence polarizations of diphenylhexatriene, pyrene excimer formation, histological changes and surface characteristics were studied. The results indicated a significant alteration in the enzyme activity as well as changes in the structure and function of the intestine in the presence of the pro-carcinogen, DMH, which suggests the possible chemopreventive efficacy of NSAIDs against the intestinal cancer.
Abstract: The role of nonsteroidal anti-inflammatory drugs (NSAIDs) was studied on the antioxidant defense system and nitric oxide-derived damage in a 1,2-dimethylhydrazine (DMH)-induced rat colon carcinogenesis. Early precancerous lesions were established in the proximal and distal regions of the colon by morphological and histopathological examinations that were greatly regressed by the simultaneous treatment of the three NSAIDs, such as aspirin, celecoxib, and etoricoxib, along with the procarcinogen DMH. The intestinal brush border membrane (BBM) was isolated from the two regions and the colon-specific marker enzyme cysteine-sensitive alkaline phosphatase was assayed, which showed considerable elevation by DMH but reverted back to normal level by all the three NSAIDs. DMH also caused a higher level of lipid peroxidation as measured by malonyldialdehyde production, which was also found to be corrected by the NSAIDs, in both the region of the colonic tissue. The antioxidant activities were further established by a higher level of superoxide dismutase, catalase, glutathione reductase, and glutathione S-transferase in the NSAID treatment as compared to the DMH. The nonenzyme tripeptide, glutathione content was also recovered similarly as an antioxidant defense mechanism. To elucidate whether nitric oxide (NO) also plays an important role in the pathophysiology of colon cancer, the NO and citrulline levels were measured. The results show that the NO was lowered in DMH treatment and elevated by the administration of the NSAIDs while the citrulline level could not be recovered back. The findings of the present investigation indicate the chemopreventive modalities of the NSAIDs, particularly the COX-2 inhibitors.
Abstract: The present study was designed to evaluate the effects of three nonsteroidal anti-inflammatory drugs (NSAIDs) with varying cycloxygenase selectivities on the small intestinal antioxidant enzyme status and surface characteristics during 1,2-dimethylhydrazine (DMH) administration. Male Sprague-Dawley rats were divided into five different groups: Group 1 (control, vehicle treated); group 2 (DMH treated, 30 mg/kg body weight/week, subcutaneously); group 3 (DMH + aspirin 60 mg/kg body weight); group 4 (DMH + celecoxib 6 mg/kg body weight); group 5 (DMH + etoricoxib 0.64 mg/kg body weight). Postmitochondrial fraction were isolated from the intestinal segments and different oxidative parameters and other parameters studied, such as the lipid peroxides, reduced and total glutathione, superoxide dismutase, catalase, glutathione reductase, glutathione S-transferase, nitric oxide, citrulline, and nucleic acids. At the end of 6 weeks of treatment, the results indicated a significant alteration in the antioxidative defense status of the intestine in the presence of the procarcinogen DMH, which was restored with the administration of NSAIDs. The study, therefore, suggests a possible mechanism for the chemopreventive effects of NSAIDs against the experimental intestinal cancer in rats.
Abstract: ABSTRACT To gain insight into the chemopreventive effects of etoricoxib, which is a selective inhibitor of cycloxygenase-2, a study was carried out in the procarcinogen 1,2-dimethylhydrazine-treated rat intestine. The male Sprague Dawley rats were divided into three different groups. Group 1 served as control (vehicle treated). All animals in Group 2 were given a weekly subcutaneous injection of 1,2-dimethylhydrazine (DMH; 30 mg/kg body weight) for 6 weeks. Group 3 animals were given an additional oral dose of etoricoxib (6 mg/kg body weight) along with weekly DMH injections for 6 weeks. At the end of 6 weeks of treatments, the results indicated significant alterations in the biochemical parameters, membrane lipid composition, and membrane fluorescence studies of the intestine in the presence of DMH, which were recovered nearly to the control level and, therefore, may suggest the chemopreventive efficacy of etoricoxib against the experimental intestinal cancer in rats.
Abstract: Oxidative stress has been implicated in brain ageing and in age-related neurodegenerative disorders. Since N-acetylcysteine (NAC) has recently been shown to prevent oxidative damage in ageing brain, we have examined the effects of this thiolic antioxidant on the age associated oxidative stress related parameters in rat brain regions. The lipid peroxide formation, reduced glutathione (GSH) content along with the activities of superoxide dismutase (SOD) and catalase were determined in the cerebral cortex and cerebellum brain regions of the young (4 months) and older (14 months) female rats. The lipid peroxidation was observed to be increased in the cerebral cortex regions accompanied by simultaneous decrease in the GSH content in both the regions of older rats. The SOD activity was reduced in both the regions while catalase was reduced only in cerebellum region of the older rats. Following NAC supplementation (160 mg/kg. b. wt./ day), lipid peroxidation was observed to be reduced which was accompanied by enhanced GSH levels, along with enhanced SOD and catalase in both the brain regions of older age rats. Further, in the younger age rats the NAC treatment resulted in the decrease of lipid peroxidation in both the regions that was accompanied by the increase catalase activity in cerebral cortex region along with increase in GSH content and SOD in cerebellum regions. Our result suggests that the normal brain ageing is associated with the decrease in antioxidative defense status and the supplementation of thiol antioxidants like NAC may prove helpful in managing the age related brain disorders characterized by compromised antioxidative defense systems.
Abstract: Nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin, celecoxib, and etoricoxib are reported to act as chemopreventive agents in experimental colon cancer induced by 1,2-dimethylhydrazine (DMH) as they are known cyclooxygenase (COX) enzyme inhibitors. To determine whether NSAIDs can also effectively modulate the membrane lipid compositions and the fluidity parameters of colonic brush border membrane, rats were injected subcutaneously (s.c.) with DMH 30 mg/kg body weight per week for 6 weeks. The animals were simultaneously treated with NSAIDs orally at the dose of aspirin, 60 mg/kg body weight; celecoxib, 6 mg/kg body weight; and etoricoxib, 0.6 mg/kg body weight. The animals were sacrificed after 6 weeks of treatments. Brush border membrane was isolated from proximal and distal portions of the colon. Membrane lipids were extracted and analyzed while the fluidity parameters were assessed by steady-state fluorescence polarization technique using the membrane extrinsic fluorophore 1,6-diphenyl-1,3,5-hexatriene (DPH). The translational diffusion was measured by using the excimer formation of pyrene incorporated in the membrane. Colonic mucosal changes in DMH alone and DMH+NSAID treated animals were assessed histologically. The results demonstrate that (a) there is a distinct occurrence of premalignant alterations in DMH-induced colon in the form of multiple plaque lesions (MPLs), which were greatly reduced by the NSAIDs used, (b) the membrane lipid changes in DMH-induced colon were completely restored back, (c) the alterations in membrane fluorescence polarization and the fluidity parameters are partially recovered, particularly with etoricoxib, and (d) the pyrene excimer formation process was completely restored. It may be concluded that the NSAIDs, particularly the coxib group of the drugs (COX-2 selective), are effective in chemoprevention in the DMH-induced colon carcinogenesis and membrane alterations.
Abstract: ABSTRACT The anticancer efficacy of two different classes of NSAIDs, the nonspecific cyclooxygenase (COX) inhibitor aspirin and the specific COX-2 inhibitor celecoxib, was examined at their therapeutic anti-inflammatory doses during 1,2-dimethylhydrazine (DMH)-induced colon carcinogenesis in a rat model. Eight to 10-week-old male rats of Sprague strain were divided into four groups. While group 1 served as control and received the vehicle of the drugs, groups 2, 3, and 4 were administered freshly prepared DMH in 1 mM EDTA saline (pH 7.0) (30 mg/kg body weight/week, subcutaneously). Groups 3 and 4 were also given a daily treatment of aspirin (60 mg/kg body weight, orally) and celecoxib (6 mg/kg body weight, orally), respectively, both prepared in carboxy-methyl cellulose. Animals were sacrificed at the end of 12 weeks and colons from different groups were subjected to macroscopic and histopathological studies, enzymatic activities of superoxide dismutase (SOD) and catalase (CAT), and determination of lipid peroxide level. The maximum number of raised mucosal lesions in proximal, middle, and distal regions of the colon was found in the DMH group alone, and the lowest number was found in the celecoxib-treated DMH group. Histological studies also showed the highest occurrence of dysplastic aberrant crypt foci (ACF) associated with enlarged lymphoid follicles in all the three portions of colon (i.e., proximal, middle, and distal). The aspirin-administered DMH group had lesser ACF in the proximal and middle portions and no ACF in the distal region. The celecoxib-administered DMH group showed no ACF in the middle region of the rat colon. DMH treatment induced lipid peroxidation and inhibited the activities of SOD and CAT. Both the aspirin- and celecoxib-treated DMH groups showed a marked lowering of the lipid peroxide level along with a significant enhancement of CAT activity when compared with the DMH-treated group. The results show that celecoxib was found to be more effective in reducing the ACF occurrence and aggregates of lymphoid tissue than the nonselective COX inhibitor aspirin, and suggests a possible chemoprevention modality in colon cancer. This may have important implications as COX-2 selective drugs at anti-inflammatory doses are better tolerated clinically than standard NSAIDs, thus making them potentially better chemopreventive agents in colon cancer.
Abstract: ABSTRACT The present study pertains to the modulator action of N-acetylcysteine (NAC) on glutathione (GSH) status in lead-exposed brain regions of the rat. The effect of lead at a dose of 20 mg/kg body weight/day was studied on the cerebral cortex and cerebellum region of rat brain. The results showed a significant decline in the reduced glutathione level in the cerebellar and cerebral tissue homogenates. Histological analysis of the different brain regions also revealed a marked deterioration in the organization of the pyramidal cellular layer of the cerebrum and the Purkinje's cellular layer of the cerebellum. The animals that underwent lead treatment when administrated with N-acetylcysteine at a dose of 160 mg/kg body weight/day showed a significant recovery of the GSH level in the brain region, while it reached almost the normal level in the cerebellum. NAC treatment also brought about appreciable improvement in the histoarchitecture of the cellular layers, which showed clearly that NAC may play a very useful role in arresting the neurotoxicological damage of lead in cerebral and cerebellar brain regions.
Abstract: The carboxylic antibiotic ionophore monensin is well-known for the Na+/H+ exchanger activity across the biological membranes. The current study has been designed to investigate the effect of monensin on spermatozoal concentration, motility, and oxidative stress-related parameters in the rat epididymis. Monensin was administered orally at a dose of 3.5 mg/kg body weight daily for 70 days, a duration that coincides with the completion of the spermatogenic cycle. At the end of the respective treatment, the epididymis was isolated into three separate regions--the capitum, corpus, and the cauda--successively away from the head of the testis. Marked changes were noted in the body weight, organ (epididymis) weight, sperm concentration and motility, as well as the morphologic observations of the sperm and the histologic architecture of the epididymal epithelium. Significant alterations were also recorded in the oxidative stress parameters such as the lipid peroxidation product, malonyldialdehyde, and the activity of superoxide dismutase, glutathione sulfotransferase, glutathione reductase, and catalase. The nonenzymatic thiol content such as the total, oxidized, and reduced glutathione showed significant changes and the tissue phosphatases such as alkaline and acid phosphatase were increased, indicative of the interference of the drug in lysosomal and Golgi membrane complex. The findings of the current study indicate interactions during the spermatozoal maturational process in the epididymis, and a significant potential use of monensin in male contraception may be suggested.
Abstract: In the present study the effects of two cycloxygenase-2 (COX-2) selective inhibitors, celecoxib and nimesulide as compared to a non-selective COX inhibitor, aspirin was studied in the rat intestine. Female Wistar rats weighing between 150-175 g were divided into four groups having 8 animals each as follows: Group 1(Control), Group 2- Aspirin (40 mg/kg), Group 3- Nimesulide (10 mg/kg) and Group 4- Celecoxib (10 mg/kg). After 35 days of treatment the animals were sacrificed, intestine removed and the effects on the antioxidant defense system, membrane composition and functions along with the membrane specific enzymes were studied in different regions of the intestine. The study showed a significant increase in the lipid peroxide levels as TBA-reactive substance as well as the conjugated dienes, except for celecoxib treated group which showed a decrease. Significant decrease was also observed in the level of reduced glutathione (GSH), superoxide dismutase (SOD), glutathione-s-transferase and catalase activities for aspirin and nimesulide group while Celecoxib caused an increase in glutathione reductase (GR). Aspirin and nimesulide exhibited an increase in the brush border membrane (BBM) bound enzyme activities like sucrase, lactase, maltase and alkaline phosphatase in the small intestine while celecoxib showed decrease in lactase, maltase and alkaline phosphatase. The phospholipid content increased only for aspirin treated group while cholesterol decreased in all the treatment groups. Also celecoxib treatment brought about an increase in glycolipid content. The membrane fluidity was studied by the rotational diffusion of 1, 6, diphenyl, 1, 3, 5 hexatriene (DPH) incorporated in the membrane and the fluorescence polarization (p), fluorescence anisotropy(r), anisotropy parameter [r0/r-1](-1) and order parameter [S2 = (4/3r - 0.1)/r0] were recorded. No significant change in the fluorescence parameters were observed in the BBM and the liposomes made from the BBM lipids for the treatment groups. These results indicate that celecoxib may be accepted as a safer drug in terms of overall gastro-intestinal toxicity as compared to the aspirin and nimesulide.
Abstract: Monensin, a carboxylic ionophore, is well known for Na(+)/H(+) exchanger activity across biological membranes. It is also used in the poultry industry for its useful effects as a food additive. The present study has been designed to investigate the effects of monensin on some oxidative stress-related parameters in rat testis. Monensin was administered intratesticularly (5 mug/testis) to both testes by a single dose to Wistar rats for different time periods. After the completion of the respective treatments, various parameters reflecting the antioxidant defense system of the tissue were monitored and marked changes were found in the activities of various enzymes as well as in the levels of reduced glutathione and lipid peroxidation. After 1, 2, 3, and 4 days of monensin treatment, the activity of superoxide dismutase was found to be unaltered. However, after 2 days of monensin treatment, glutathione-S-transferase and catalase showed inhibition in their activities along with the depletion of glutathione (reduced) accompanied by a marked increase in lipid peroxidation. The increase in lipid peroxidation was noticeable even after 1 day of monensin administration. The inhibition in glutathione-S-transferase and glutathione peroxidase activities was also observed along with an increase in lipid peroxidation at the end of the 3-day posttreatment period, while, the 4-day posttreatment schedule caused an increase in the activity of glutathione reductase and glutathione peroxidase that was also accompanied by an inhibition of catalase. The findings of the present study are indicative of the potential of monensin in testicular tissue in contraceptive intervention.
Abstract: Functional interactions of lipids and proteins were examined in brush-border membranes isolated from the kidney cortex by studying the temperature dependence of the hydrolytic enzyme activities. A close relationship was observed for the membrane proteins and the thermotropic lipid phase transitions. Three lines of evidences were provided for such dependence: a) Arrhenius relationship of the membrane-bound enzyme activities, and the effect of temperature in native and partially delipidated membranes, b) differential scanning calorimetric study of the membrane lipid phase transitions in the native and delipidated membranes, multilamellar vesicles prepared from the membrane extracted lipids, and in vesicles from dimyristoyl phosphatidylcholine, and c) the excimer (dimer)-formation studies of the membrane extrinsic fluorescent probe, pyrene, and the resultant membrane microviscosity. The brush-border membranes were partially delipidated with BuOH and 2,2,2-trifluoroethanol. The functional interactions of the delipidated membranes, which were greatly lost on lipid removal, were largely restored by the addition of exogenous lipids in the reconstitution process, which indicate the critical dependence of the membrane integral proteins on the neighboring lipid molecules in the bulk lipid phase.
Abstract: Incubation of placental brush border membrane (BBM) along with sonicated vesicles of exogenous lipids (egg yolk PC) in the presence of phospholipid-transfer protein (PL-TP) showed a decrease in the alkaline phosphatase activity due to the change in the membrane micro-environment, such as fluidity. Effect of substrate concentration was tested by Lineweaver-Burk plot, which showed decreased V(max) and K(M). The effect of temperature was probed by the Arrhenius plot, which showed no change in transition temperature, but a decline in the energy of activation both below and above the transition temperature. The protein-catalyzed transfer of phospholipid from the donor unilamellar vesicles resulted in a substantial increase in the BBM phospholipid and a net decrease in cholesterol/phospholipid molar ratio. The change in membrane fluidity was assessed by translational as well as rotational diffusion of membrane extrinsic fluorescent probes, pyrene and diphenyl-hexatriene. An increased lateral mobility was recorded by the increased pyrene excimer formation. A decrease in fluorescent polarization of diphenyl-hexatriene was observed, which led to the decrease in fluorescence anisotropy and order parameter, and therefore, an increase in membrane fluidity (rotational diffusion). Mean anisotropy parameter was also decreased in the presence of PL-TP. Thus, the placental BBM alkaline phosphatase activity showed a distinct lipid dependence which may have important physiological consequences.
Abstract: Lead (Pb) is known to disrupt the pro-oxidant/antioxidant balance of tissues, which leads to biochemical and physiological dysfunction. Oxidative stress is considered a possible molecular mechanism involved in Pb neurotoxicity. Considering the vulnerability of the brain to oxidative stress under Pb neurotoxicity, this study investigated the effects of exposure of the thiol antioxidant N-acetylcysteine (NAC) on lead-induced oxidative damage and lipid peroxidation in brain regions of the rat. Wister strain rats were exposed to lead in the form of lead acetate (20 mg/kg body wt/d) for a period of 2 wk and the effects of NAC on lead-induced neurotoxicity in rat brain regions were assessed by postadministration of NAC (160 mg/kg body wt/d) for a period of 3 wk. The lipid peroxidation byproduct, malondialdehyde (MDA) increased following lead exposure in both of the regions, and the antioxidant capacities of the cell in terms of the activity of antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) was diminished. Following NAC treatment, lead-induced lipid peroxidation decreased and antioxidant enzyme activities improved, with CAT showing enhancement in the cerebral region only and SOD showing enhancements in the cerebellar region. Our result suggests that thiol-antioxidant supplementation following Pb exposure might enhance the reductive status of brain regions by arresting the lipid peroxidative damage in brain regions.
