Biomedical subjects

C V Rao

Publications and source records attributed to C V Rao.

At least 91 records · Page 5Linked to original sources

PubMed1998

Mitogen-activated protein kinase is involved in epidermal-growth-factor-regulated protein phosphorylation in nuclear membranes isolated from JEG-3 human choriocarcinoma cells.

The treatment of highly purified nuclear membranes isolated from JEG-3 human choriocarcinoma cells with epidermal growth factor (EGF) resulted in an increase of the receptor autophosphorylation and the phosphorylation of several other proteins, including 44-kDa, 34-kDa and 24-kDa proteins, and a decrease in the phosphorylation of a 40-kDa protein. The kinetics of phosphorylation and the use of RG-13022, a selective inhibitor of EGF-receptor kinase activity, suggested that receptor activation was necessary for the phosphorylation response of the other proteins. Tyr was exclusively phosphorylated in the EGF receptor and 24-kDa proteins, Tyr and Thr were phosphorylated in the 44-kDa protein, and Ser was phosphorylated in the 34-kDa protein and dephosphorylated in the 40-kDa protein. The molecular size, Thr/Tyr phosphorylation, immunoprecipitation and enzymatic activity towards myelin basic protein suggested that the 44-kDa protein was a mitogen-activated protein (MAP) kinase. The EGF treatment not only increased phosphorylation but also catalytic activity of MAP kinase and these increases were prevented by the addition of RG-13022. In summary, this report demonstrates that target cell nuclei contain EGF receptors, which use the MAP kinase signaling pathway.

Calcium-Calmodulin-Dependent Protein Kinases↗

PubMed1998

Chemopreventive activity of celecoxib, a specific cyclooxygenase-2 inhibitor, against colon carcinogenesis.

Epidemiological and laboratory studies suggest that nonsteroidal antiinflammatory drugs reduce the risk of colon cancer and that the inhibition of colon carcinogenesis is mediated through modulation of prostaglandin production by cyclooxygenase (COX) isozymes (COX-1 and -2). Overexpression of COX-2 has been observed in colon tumors; therefore, specific inhibitors of COX-2 activity could potentially serve as chemopreventive agents. Our recent study indicated that celecoxib (SC-58635), a specific COX-2 inhibitor, suppressed colonic aberrant crypt foci formation induced by azoxymethane in rats and led us to investigate more specifically the chemopreventive potential of this compound using colon tumors as end points. Five-week-old male F344 rats were fed the control diet (modified AIN-76A) or an experimental diet containing 1500 ppm celecoxib. Two weeks later, all animals except those in the saline-treated groups received s.c. injections of azoxymethane (15 mg/kg of body weight) once weekly for 2 weeks. All groups were kept on their regimen until the experiment was terminated, 50 weeks after carcinogen treatment. Colon tumors were evaluated histopathologically. Remarkably, dietary administration of celecoxib inhibited both incidence and multiplicity of colon tumors by about 93 and 97%, respectively. It also suppressed the overall colon tumor burden by more than 87%. The degree of tumor inhibition was more pronounced with celecoxib than it was with previously evaluated nonsteroidal anti-inflammatory drugs. The results of this study provide evidence, for the first time, that a specific COX-2 inhibitor, celecoxib, possesses strong chemopreventive activity against colon carcinogenesis.

Animals↗

PubMed1998

The urinary bladder of a woman is a novel site of luteinizing hormone-human chorionic gonadotropin receptor gene expression.

OBJECTIVE: The female reproductive tract contains functional luteinizing hormone-human gonadotropin receptors; therefore our objective was to test the hypothesis that bladder trigone, which is derived from intermediate mesoderm along the urogenital ridge during embryonic development of the female reproductive tract, may also contain these receptors. STUDY DESIGN: Bladder trigones or domes were biopsied from 15 premenopausal and 19 postmenopausal women undergoing surgical correction of genital prolapse, incontinence, or both. The biopsy specimens were submitted for luteinizing hormone-human chorionic gonadotropin receptor analysis by in situ hybridization and immunocytochemical examination. The receptor immunostaining was visually scored by 3 investigators without knowing the identity of the menopausal status. RESULTS: In situ hybridization demonstrated the presence of receptor transcripts, and immunocytochemical examination revealed the presence of receptor protein in bladder trigone. The bladder trigones from postmenopausal women contained lower levels compared with those from premenopausal women, implying that luteinizing hormone might down-regulate its own receptors. Transitional epithelium contained the highest receptor levels followed by smooth muscle and blood vessels. The bladder dome contained receptor levels similar to those in trigone, which suggests that a common embryologic origin is not the only reason for bladder trigone containing the luteinizing hormone-human chorionic gonadotropin receptors. Rather, they are present because luteinizing hormone-human chorionic gonadotropin may regulate bladder functions in women. CONCLUSIONS: A woman's urinary bladder, which has never been thought of as a gonadotropin target, has now been demonstrated to contain luteinizing hormone-human chorionic gonadotropin receptors. These findings suggest for the first time that gonadotropins directly regulate bladder functions in women.

Adult↗

PubMed1998

Localization of receptors for luteinizing hormone/chorionic gonadotropin in neural retina.

Although the expression of the luteinizing hormone (LH)/human chorionic gonadotropin (CG) receptor gene has been traditionally thought to be restricted to gonadal tissue, recent studies have shown that LH/CG receptors are present in many regions of the central nervous system (CNS), as well as in peripheral tissues. We now report the characterization of LH/CG receptor gene expression in the neural retina, a component of the CNS. Transcript levels in the retina are approximately equal to levels present in the cerebral cortex, but are at least 100 fold lower than the levels in testis. The density of LH/CG receptor transcripts, receptor protein and 125I-CG binding is the highest in the photoreceptor cells and then decreased throughout the inner retina. Our study is the first to demonstrate the presence of LH/CG receptors in the neural retina. This finding raises the possibility that photoreceptor cells have the potential to mount cellular responses to LH/CG that may impact on visual processing, and poses an intriguing connection to the proposed role of gonadotropins in the progression of proliferative retinopathy.

Animals↗

PubMed1998

Analysis of the promoter of the luteinizing hormone/human chorionic gonadotropin receptor gene in neuroendocrine cells.

We investigated the molecular basis of luteinizing hormone (LH)/human chorionic gonadotropin (hCG) receptor gene transcription in immortalized alphaT3 gonadotropes, hypothalamic GT1-7 and hippocampal HN33p neurons. Nuclear run-on transcription, as well as transfection assays with fusion constructs of luciferase and the 5'-flanking region of LH/hCG receptor gene, revealed that GT1-7 neurons transcribe more than the alphaT3 or HN33p cells. Transient transfection of truncated reporter gene constructs and gel mobility shift assays revealed that while all neuroendocrine cells use the same promoter, they contain different levels of promoter binding proteins. Higher levels of these proteins may explain increased transcription of the LH/hCG receptor gene in GT1-7 neurons compared with alphaT3 and HN33p cells.

Animals↗

PubMed1998

Prevention of colonic aberrant crypt foci and modulation of large bowel microbial activity by dietary coffee fiber, inulin and pectin.

The present experiments were aimed at developing novel dietary fibers to aid in reduction of colon cancer risk. We assessed the effects of coffee (non-fiber fraction), coffee fiber (arabino-galactose polymer) and inulin (oligo-fructose) in male F344 rats using formation of azoxymethane (AOM)-induced aberrant crypt foci (ACF) in the colon as the measure of preventive efficacy (or lack of such). At 5 weeks of age, groups of rats were fed the AIN-76A (control) and experimental diets that contained 1% coffee, 10% coffee fiber, 10% inulin, 10% pectin (positive control for fiber) or 200 p.p.m. piroxicam (a known ACF inhibitor). At 7 weeks of age, all animals were s.c injected with AOM (15 mg/kg body wt) once weekly for 2 weeks. All rats were killed 8 weeks after the last AOM injection and ACF were counted. The contents of the cecum were analyzed for bacterial beta-glucuronidase activity and short-chain fatty acids (SCFAs). Dietary administration of coffee fiber significantly suppressed AOM-induction of colonic ACF, in terms of total number, as well as crypt multiplicity and number of ACF/cm2 colon (P < 0.01-0.001). Inulin diet had no significant effect on total ACF, but had reduced the number of ACF/cm2 (P < 0.05). Whereas coffee had no effect on ACF formation, 10% pectin diet and 200 p.p.m. piroxicam significantly suppressed colonic ACF (P < 0.001) as had been expected. A significant reduction of cecal beta-glucuronidase activity was observed in the rats fed coffee, coffee fiber and pectin diets. Further, coffee fiber, inulin and pectin increased cecal SCFA levels 3- to 5-fold. These results suggest that coffee fiber can prevent colon cancer risk. Further studies are warranted to determine the full potential of this fiber in pre-clinical efficacy studies.

Animals↗

PubMed1998

Chemopreventive effect of squalene on colon cancer.

Epidemiologic and laboratory studies suggest a cancer protective effect and/or lack of a tumor promoting effect by dietary olive oil as compared with other types of non-marine oils. Squalene, a constituent of olive oil, and a key intermediate in cholesterol synthesis may be regarded as partially responsible for the beneficial effects of olive oil, which include decreased mortality rates among populations with high olive oil consumption. Thus, in this study we have assessed the chemopreventive efficacy of squalene on azoxymethane (AOM)-induced colonic aberrant crypt foci (ACF). In addition, we measured the effect of squalene on serum cholesterol levels in the rats. Male F34 rats (5 weeks old) were fed the control diet (modified AIN-76A) or experimental diets containing 1% squalene or 320 p.p.m. sulindac. Two weeks later, all animals except those in vehicle (normal saline)-treated groups were s.c. injected with AOM (15 mg/kg body wt, once weekly for 2 weeks). At 16 weeks of age, all rats were killed, colons were evaluated for ACF and serum was assayed for the cholesterol levels. As expected, dietary administration of sulindac suppressed ACF development and reduced crypt multiplicity, i.e. number of aberrant crypts/focus. Administration of dietary squalene inhibited total ACF induction and crypt multiplicity by approximately >46% (P < 0.001). Further, squalene at a level of 1% did not show any significant effect on serum cholesterol levels. Our finding that squalene significantly suppresses colonic ACF formation and crypt multiplicity strengthens the hypothesis that squalene possesses chemopreventive activity against colon carcinogenesis.

Animals↗

PubMed1998

Luteinizing hormone and human chorionic gonadotropin decrease type 2 5 alpha-reductase and androgen receptor protein levels in women's skin.

The present study tested the hypothesis that LH/hCG may regulate the type 2 5 alpha-reductase and androgen receptor protein levels in skin. The skin samples obtained from women undergoing abdominal laparotomy or abdominoplasty were incubated in the presence or absence of hCG. Western blotting was then performed to determine the response of type 2 5 alpha-reductase and androgen receptors. The results demonstrated that treatment with hCG resulted in a significant time- and dose-dependent, although modest, decrease in 5 alpha-reductase and androgen receptor levels compared to the controls. These effects were mimicked by LH, but not by other hormones in the glycoprotein hormone family, including alpha- and beta-subunits of hCG. Although the biological and clinical importance of this regulation remains to be determined, these findings reaffirm that human skin is among the nongonadal tissues that respond to LH and hCG treatment.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗

PubMed1998

Multiple pituitary and ovarian defects in Krox-24 (NGFI-A, Egr-1)-targeted mice.

The zinc finger transcription factor Krox-24 (NGFI-A, Egr-1) is encoded by an immediate-early serum response gene expressed in various physiological situations and tissues. To investigate its function, we have created a null allele. Mice homozygous for the mutation have a reduced body size, and both males and females are sterile. These phenotypes were related to defects in the anterior pituitary of both sexes and in the ovary. In the pituitary, two cell lineages expressing Krox-24 are differentially affected by the mutation: somatotropes present abnormal cytological features and are reduced in number, consistent with the decreased GH content observed in these animals; in contrast gonadotropes are normal in number, but specifically fail to synthesize the beta-subunit of LH. In the ovary, LH receptor expression is prevented, indicating an involvement of Krox-24 at two levels at least of the pituitary-gonadal axis. Our data, together with the results of a previous report describing another Krox-24 mutant allele, suggest that Krox-24 may have two distinct molecular functions in the anterior pituitary: transcriptional activation of the LHbeta gene in gonadotropes and control of cell proliferation and/or survival in somatotropes by unknown mechanisms.

Animals↗

PubMed1998

Evaluation of benzyl selenocyanate glutathione conjugate for potential chemopreventive properties in colon carcinogenesis.

Observational, clinical and experimental studies have suggested that dietary supplementation with selenium can inhibit the development of colon cancer. Since toxicity and chemopreventive efficacy of selenium compounds depend to a large extent, on the form of selenium the development of efficacious organoselenium compounds with low toxicity is being pursued in our laboratory. We have assessed the chemopreventive properties of a newly synthesized organoselenium compound, benzyl selenocyanate glutathione conjugate (BSeSG), and of benzyl selenocyanate (BSC), as a positive control, using azoxymethane (AOM)-induced colonic aberrant crypt foci (ACF) as a measure of efficacy. Five-week-old male F344 rats were fed the control diet (modified AIN-76A) or experimental diets containing 10 or 20 ppm BSeSG (1.7 and 3.4 ppm as Se, respectively), or 10 ppm BSC (4.1 ppm as Se). One week later, all animals except those in vehicle (normal saline)-treated groups were s.c. injected with AOM (15 mg/kg of body weight, once weekly for 2 weeks). All animals were sacrificed 7 weeks after the last AOM injection, and the ACF, levels of prostaglandin E2 (PGE2), cyclooxygenase protein expression (COX-1 and -2), and glutathione S-transferase type mu (GST-mu) were determined in the colon. As expected, dietary administration of BSC suppressed ACF development by about 37%. In rats administered 10 or 20 ppm BSeSG, the frequencies of AOM-induced colonic ACF were significantly decreased compared to those of rats given AOM and control diet by about 41% (P<0.01) and 61% (P<0.001), respectively. Administration of BSeSG inhibited PGE2 production (81-88% inhibition) via COX-2 synthesis in the colonic mucosa (18-60% inhibition). Also, BSeSG increased GST-mu protein activity in colonic mucosa (30-32% increase). These data suggest that a newly synthesized organoselenium compound, BSeSG might be a promising chemopreventive agent against colon carcinogenesis.

Animals↗

PubMed1997

Enhancement of experimental colon cancer by genistein.

Several phytochemicals and micronutrients that are present in fruits and vegetables are known to exert cancer chemopreventive effects in several organs, including the colon. Among them, the soybean isoflavonoid genistein received much attention due to its potential anticarcinogenic, antiproliferative effects and its potential role in several signal transduction pathways. The present study was designed to investigate the effect of genistein on azoxymethane (AOM)-induced colon carcinogenesis and to study its modulatory role on the levels of activity of 8-isoprostane, cyclooxygenase (COX), and 15-hydroxyprostaglandin F2alpha dehydrogenase (15-PGDH) in the colonic mucosa and colon tumors of male F344 rats. At 5 weeks of age, groups of male F344 rats were fed control (AIN-76A) diet or a diet containing 250 ppm genistein. Beginning 2 weeks later, all animals except those in the vehicle-treated groups were given weekly s.c. injections of AOM (15 mg/kg body weight) for 2 successive weeks. All rats were continued on their respective dietary regimen for 52 weeks after AOM treatment and were then sacrificed. Colon tumors were evaluated histopathologically. Colonic mucosae and tumors were analyzed for COX, 15-PGDH, and 8-isoprostane levels. Administration of genistein significantly increased noninvasive and total adenocarcinoma multiplicity (P < 0.01) in the colon, compared to the control diet, but it had no effect on the colon adenocarcinoma incidence nor on the multiplicity of invasive adenocarcinoma (P > 0.05). Also, genistein significantly inhibited the 15-PGDH activity (>35%) and levels of 8-iosoprostane (50%) in colonic mucosa and in tumors. In contrast, genistein had no significant effect on the COX synthetic activity, as measured by the rate of formation of prostaglandins and thromboxane B2 from [14C]arachidonic acid. The results of this investigation emphasize that the biological effects of genistein may be organ specific, inhibiting cancer development in some sites yet showing no effect or an enhancing effect on the tumorigenesis at other sites, such as the colon. The inhibition of 8-isoprostane levels by genistein indicates its possible antioxidant potential, which is independent of the observed colon tumor enhancement, yet this agent may also possess several biological effects that overshadow its antioxidant potential. The exact mechanism(s) of colon tumor enhancement by genistein remain to be elucidated; it is likely that its colon tumor-enhancing effects may, at least in part, be related to inhibition of prostaglandin catabolic enzyme activities.

Adenocarcinoma↗

PubMed1997

A novel regulation of the oviductal glycoprotein gene expression by luteinizing hormone in bovine tubal epithelial cells.

The hypothesis that bovine oviductal epithelial cells contain luteinizing hormone (LH)/human chorionic gonadotropin (hCG) receptors and LH may regulate the oviductal glycoprotein (OGP) gene expression was tested. The results showed that bovine oviductal epithelial cells contain an 80 kDa LH/hCG receptor protein which can bind [(125)I]hCG. Culturing these cells with highly purified hCG, used as a surrogate hormone for LH, resulted in a dose and time dependent increase in a 95 kDa protein and a 2.3 kb transcript of OGP. The maximal increase of 100% was obtained with 10 ng/ml hCG and after three days of culture. LH, but not other hormones in the glycoprotein hormone family, isolated subunits of hCG, estradiol-17beta or progesterone, mimicked hCG, suggesting that the effect is hormone specific and requires the conformation of native hormone. The increase in steady state OGP mRNA levels by hCG is not due to an increase in the transcription rate of the gene. It is rather due to a significant increase in the half-life of OGP transcripts from 23 h in the control to 28 h after treatment with hCG. In summary, we conclude that LH and hCG can increase the synthesis of OGP by decreasing the degradation of its transcripts in bovine oviductal epithelial cells. Since OGP may play important roles in fertilization and growth and development of early embryo, higher LH levels present during the periovulatory period may directly participate in the early pregnancy events through increasing the synthesis of OGP.

Animals↗

PubMed1997

Novel independent and synergistic regulation of gonadotropin-alpha subunit gene by luteinizing hormone/human choriogonadotropin and gonadotropin releasing hormone in the alphaT3-1 gonadotrope cells.

The alphaT3-1 cells are immortalized anterior pituitary gonadotropes which express gonadotropin-alpha subunit gene. These cells contain receptors for gonadotropin releasing hormone (GnRH) as well as for luteinizing hormone (LH) which can also bind human choriogonadotropin (hCG). Like GnRH, LH and hCG can upregulate the expression of gonadotropin-alpha subunit gene. While 0.1-1.0 ng/ml hCG can upregulate, higher concentrations have no effect. However, these higher hCG concentrations can act in a synergistic manner with GnRH to increase the steady state mRNA and protein levels of gonadotropin-alpha subunit. The synergism between hCG and GnRH was mimicked by LH but not by other hormones in the glycoprotein hormone family or alpha or beta subunits of hCG, suggesting that the synergism is hormone specific and requires the conformation of native hormone. The hCG induced increase in gonadotropin-alpha subunit mRNA levels was due to a significant increase in the half-life of gonadotropin-alpha subunit transcripts from 7.8 +/- 1.0 h in the controls to 16.5 +/- 3.8 h after treatment with hCG. The GnRH induced increase in gonadotropin-alpha subunit mRNA levels was due to both a significant increase in the half-life to 26.2 +/- 3.0 h as well as a significant increase in the transcription rate of the gene (159.0 +/- 7.7% of the control). A greater increase in gonadotropin-alpha subunit mRNA levels following a combined treatment with GnRH and hCG was due to a further increase in half-life to 37.6 +/- 3.1 h as well as a greater increase in the transcription rate of the gene (295.1 +/- 24.2% of the control) as compared to the treatment with GnRH alone. In summary, we conclude that LH and hCG can independently and synergistically act with GnRH to increase the expression of gonadotropin-alpha subunit gene by transcriptional as well as by post-transcriptional mechanisms in alphaT3-1 cells. These effects may be important for the increase of LH levels during the preovulatory surge.

Animals↗

PubMed1997

cis-Acting elements and trans-acting proteins in the transcriptional inhibition of gonadotropin-releasing hormone gene by human chorionic gonadotropin in immortalized hypothalamic GT1-7 neurons.

We investigated the cis-acting elements and trans-acting proteins required for the transcriptional inhibition of the gonadotropin-releasing hormone (GnRH) gene by human chorionic gonadotropin (hCG) in GT1-7 neurons. Transient transfection of GT1-7 neurons with the 5'-flanking region of the rat GnRH gene-luciferase fusion constructs revealed that a 53-base pair (bp) sequence between -126 and -73 bp is required for the hCG inhibition. Nuclear extracts from GT1-7 neurons contained 110- and 95-kDa proteins that formed two complexes with the 53-bp sequence. These proteins are not related to Fos, cAMP response element-binding protein, Oct-1, or progesterone receptors, and hCG treatment selectively increased the 95-kDa protein. DNase I footprinting with GT1-7 cell nuclear extracts protected the -99 to -79-bp region, which contained a so-called imperfect AP-1 site (-99 to -94 bp) and two AT-rich palindromic sequences (-91 to -87 bp and -85 to -81 bp). The mutagenesis of the AT-rich regions, but not the AP-1 site, resulted in a loss of DNA binding of the 95-kDa protein and the inhibitory effect of hCG. In summary, our results are consistent with hCG inducing a 95-kDa trans-acting protein, which binds to -91- to -81-bp AT-rich sequences in the 5'-flanking region to inhibit the transcription of the GnRH gene.

Animals↗

PubMed1997

Chemoprevention of colon cancer by organoselenium compounds and impact of high- or low-fat diets.

BACKGROUND: Observational and experimental studies have suggested that dietary supplementation with selenium can inhibit the development of colon cancer. However, many forms of selenium are toxic. Consequently, the development of efficacious compounds with low toxicity has been pursued. PURPOSE: Two synthetic organoselenium compounds, p-methoxy-benzyl selenocyanate (p-methoxy-BSC) and 1,4-phenylenebis(methylene)selenocyanate (p-XSC), were tested for their ability to inhibit colon carcinogenesis in rats that were treated with the carcinogen azoxymethane and fed low- or high-fat diets. METHODS: Groups of 5-week-old male F344 rats (42 animals/ group) were fed either a high-fat diet or a low-fat diet with or without added p-methoxy-BSC (10 or 20 parts per million [ppm]) or p-XSC (20 ppm). Two weeks later, 30 animals in each group received a subcutaneous injection of azoxymethane (15 mg/kg body weight); 1 week later, they received a second injection. The remaining 12 rats in each group received two injections of saline. Three days after the second injection of carcinogen or saline, animals being fed diets with p-methoxy-BSC or p-XSC were switched to corresponding organoselenium-free low- or high-fat diets for the remainder of the study to determine the effects of the selenium compounds on the initiation phase of colon carcinogenesis. At that time, groups of animals that had been maintained on organoselenium-free low- or high-fat diets were switched to diets containing p-methoxy-BSC or p-XSC until the end of the study to determine the effects of these compounds on the postinitiation phase of colon carcinogenesis. All animals were killed during the 38th week after azoxymethane or saline treatment, and histopathologic analysis of the colon tumors was performed. Colon tumor incidence and multiplicity were analyzed statistically. RESULTS: No obvious toxic effects were observed following dietary administration of 10 or 20 ppmp-methoxy-BSC or 20 ppm p-XSC. Administration of 20 ppm p-methoxy-BSC in a high-fat diet during the initiation and postinitiation phases of colon carcinogenesis significantly (statistically) reduced colon tumor incidence; 10 ppmp-methoxy-BSC in a high-fat diet significantly reduced colon tumor incidence but only when it was given during the postinitiation phase. Colon tumor incidence was also significantly reduced when 20 ppm p-XSC was given in a high-fat diet during the initiation phase of colon carcinogenesis. When 20 ppm p-XSC was administered in either a high-fat diet or a low-fat diet during the postinitiation phase, both colon tumor incidence and multiplicity were significantly reduced; the greatest reductions were in animals fed a low-fat diet. CONCLUSIONS: In this model system, p-methoxy-BSC and p-XSC are effective agents for the chemoprevention of colon cancer. The effects of p-XSC were enhanced in animals fed a low-fat diet.

Adenocarcinoma↗

PubMed1997

Modulation of apoptosis by sulindac, curcumin, phenylethyl-3-methylcaffeate, and 6-phenylhexyl isothiocyanate: apoptotic index as a biomarker in colon cancer chemoprevention and promotion.

Recent evidence supports the theory that tumor growth in vivo depends on evasion of normal homeostatic control mechanisms that operate through induction of cell death by apoptosis. This study tested the hypothesis that several potential chemopreventive agents share the ability to induce apoptosis and that inhibition of apoptosis is a mechanism of tumor promoters. The present study was designed to investigate whether the chemopreventive properties of sulindac, curcumin, and phenylethyl-3-methylcaffeate (PEMC) and the tumor-promoting activity of 6-phenylhexyl isothiocyanate (PHITC) that were observed in our previous studies are associated with the induction or inhibition of apoptosis in azoxymethane (AOM)-induced colon tumors in male F344 rats. At 5 weeks of age, groups of rats were fed control (modified AIN-76A) diet or diets containing 320 ppm of sulindac, 2000 ppm of curcumin, 750 ppm of PEMC, or 640 ppm of PHITC. At 7 weeks of age, all rats except those intended for vehicle (normal saline) treatment were given AOM (15 mg/kg body weight) once weekly for 2 weeks. To study the effect of sulindac administered during promotion/progression stage, the rats were fed the control diet initially and then fed the experimental diet containing 320 ppm of sulindac 14 weeks after the second AOM treatment. The rats were sacrificed 52 weeks after carcinogen treatment, and their colonic tumors were subjected to histopathological evaluation and the appearance of apoptosis. In the current study, chronic administration of sulindac, curcumin, and PEMC or sulindac given only during promotion/progression significantly increased the apoptotic index (percentage of apoptosis) as compared to administration of the control diet; the apoptotic indices in the control, sulindac, curcumin, and PEMC diets were 8.3, 17.6, 17.7, and 18.5%, respectively, and in sulindac administered during promotion/progression stage, the apoptotic index was 19.1%. However, dietary PHITC blocked the process of apoptosis during colon carcinogenesis. The apoptotic index in PHITC diet was 7.0%. Taken together, our data show that chemopreventive properties of agents are correlated with the degree of apoptosis. Therefore apoptosis seems to be a reliable biomarker for the evaluation of potential agents for cancer prevention.

Adenocarcinoma↗

PubMed1997

Chemoprevention of colon carcinogenesis by dietary perillyl alcohol.

Epidemiological studies suggest that consumption of diets containing fruits and vegetables, major sources of phytochemicals and micronutrients, may reduce the risk of developing cancer of the colon. Several phytochemicals and micronutrients present in fruits and vegetables are known to exert cancer-chemopreventive effects in several organs, including the colon. Monoterpenes such as d-limonene and perillyl alcohol derived from orange peels and lavender, respectively, have been shown to possess chemopreventive properties against mammary, liver, and/or lung carcinogenesis. The present study was designed to investigate the efficacy of dietary 40 and 80% maximum tolerated dose (MTD) levels of perillyl alcohol on azoxymethane (AOM)-induced colon carcinogenesis. The effect of this agent on the process of apoptosis in colon tumors was also investigated. Prior to the efficacy study, the MTD of perillyl alcohol was determined in male F344 rats in a 6-week subchronic toxicity study and found to be a 2.5-g/kg diet when added to the AIN-76A diet. At 5 weeks of age, groups of male F344 rats were fed control (AIN-76A) diet or diets containing 1 and 2 g perillyl alcohol/kg diet, representing 40 and 80% MTD levels, respectively. At 7 weeks of age, all animals except those in the vehicle-treated groups were given two weekly s.c. injections of AOM (15 mg/kg body weight/week). All animals were continued on their respective dietary regimen for 52 weeks after AOM treatment and then sacrificed. Colon tumors were evaluated histopathologically using routine procedures. Perillyl alcohol at the 1-g/kg level significantly inhibited the incidence (percentage of animals with tumors) and multiplicity (tumors/ animals) of invasive adenocarcinomas of the colon, whereas perillyl alcohol at 2 g/kg diet inhibited the incidence of total adenocarcinomas of the colon and small intestine as compared to the control diet. Our studies also indicate that the colon tumors of animals fed perillyl alcohol exhibited increased apoptosis as compared to those fed the control diet. These results demonstrate the potential chemopreventive activity of perillyl alcohol against colon carcinogenesis. The chemopreventive activity of perillyl alcohol is mediated through the tumor cell loss by apoptosis.

Adenocarcinoma↗

PubMed1997

Increased expression of LH/hCG receptors in endometrial hyperplasia and carcinoma in anovulatory women.

Endometrial hyperplasias and carcinomas are well documented to occur in anovulatory women with or without polycystic ovarian syndrome (PCO), which is characterized by hypersecretion of luteinizing hormone (LH). Although overexpression of LH/human chorionic gonadotropin (hCG) receptors has been demonstrated in endometrial carcinomas, whether LH/hCG receptors are also expressed in the endometrial hyperplasias is not known. In this study, the expression of LH/hCG receptors as well as that of progesterone receptors (PR) was analyzed by immunohistochemistry in 20 cases of normal endometria and 24 cases of endometrial hyperplasia and carcinoma (9 simple hyperplasias, 6 complex hyperplasias, 6 atypical hyperplasias, and 3 well-differentiated carcinomas). Fifteen of the 24 patients were 40 years old or younger, presumably anovulatory by BBT chart. Serum levels of LH, follicular stimulating hormone (FSH), prolactin, estradiol, and testosterone were measured by radioimmunoassay. Expression of LH/hCG receptors was detected in 19 of the 21 hyperplasias with a relatively stronger staining intensity in the glandular cells of complex or atypical hyperplasia as compared with normal endometrial glands or simple hyperplasia. In addition, all of the 3 carcinoma specimens showed stronger expression of LH/hCG receptors compared with normal endometria. The expression of LH/hCG receptors was well correlated with the staining for PR. Hormonal assay revealed 3 women to have the typical endocrinological profile of PCO. These findings suggest that the increased expression of LH/hCG receptors is a feature of endometrial hyperplasia and carcinoma developing in younger anovulatory women including those with PCO.

Adult↗