Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0596263 (carcinogenesis)
 64,820 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Several genetic aberrations have been implicated in the carcinogenesis of small cell lung carcinomas (SCLCs), including tumour suppressor gene p53 deletion and mutation and amplification of the myc family proto-oncogenes. However, their exact ontogeny and carcinogenesis remain unknown. There are no proven aetiological factors for lung carcinoid tumours. Recent evidence suggests that the genetic regulation of apoptosis is of critical importance during tumourigenesis and that oncogene and tumour suppressor genes can regulate the rate, or susceptibility, of cells to undergo apoptosis. In this study, the expression of Bcl-2 protein has been investigated in 77 primary lung neuroendocrine tumours, including 55 SCLCs and 22 carcinoid tumours, and compared with p53 expression. Of the 77 tumours studied, Bcl-2 immunoreactivity was present in 80 per cent of SCLCs, 43 per cent of typical, and 67 per cent of atypical carcinoid tumours with more than 10 per cent tumour cell positivity. Western and Northern blot analysis revealed that carcinoid tumours expressed the 26 kD protein and bcl-2 transcripts. Whereas 42 per cent of the SCLCs studied displayed p53 protein immunoreactivity in more than 10 per cent of tumour cells, p53 positivity was not found in lung carcinoid tumours. There are statistical differences in Bcl-2 and p53 expression between SCLCs and lung carcinoid tumours. These results suggest that disregulation of the genetic mechanisms controlling apoptosis is a critical step in the progression of SCLC, and the expression of Bcl-2 is involved in the pathogenesis of SCLC and lung carcinoid tumours. The genetic complementation of simultaneously deregulated Bcl-2 and p53 may be implicated in the multistep tumourigenesis of small cell lung cancer.
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PMID:Expression of Bcl-2 in lung neuroendocrine tumours: comparison with p53. 961 75

Recent publications have associated p53 and bcl-2 genes in the process of neoplastic transformation. As the colonic adenoma-carcinoma sequence is an adequate natural model for carcinogenesis, it was considered interesting to analyze the expression of bcl-2 and p53 in these neoplasms. Seventy three adenomatous polyps (adenomas) and 60 adenocarcinomas of the colon and rectum were studied. Adenomas showed mild dysplasia in 16, moderate in 27, severe in 15 and focal carcinoma in the remaining 15. Adenocarcinomas surpassed the deep muscle layer in every case and were moderately differentiated. The studied gene expression was analized immunohistochemically using antibodies bcl-2 from Dako and p53 from Novocastra, both at a 1:100 dilution. Cytoplasmic stain for bcl-2 and nuclear stain for p53 above 10% of the cells were considered positive for each gene respectively. Results showed that there was accumulation of p53 protein in 26/58 (45%) adenomas with different grades of dysplasia. This result is similar to the reactivity found in adenomas with focal carcinoma where 8/15 (53%, p = 0.4) were positive but different from adenocarcinomas which were positive in 47/60 (78%, p = 0.0001). Regarding bcl-2, positivity was found in 53/73 (73%) of all the adenomas whereas adenocarcinoma showed expression in 14/60 (23%, p = 0.0000). When adenomas were grouped according to their degree of dysplasia and the existence of focal carcinoma, a diminishing frequency of reactivity for bcl-2 was found and when adenomas with three different grades of dysplasia were fused together, 47/58 (81%) were positive and this was compared with adenomas having focal carcinoma, 6/15 (40%) and with adenocarcinoma, 14/60 (23%), they showed significant differences (p = 0.001 and p = 0.0000 respectively). The analysis of the frequency of expression for both genes studied in the different lesions described yielded an inverse relation between them. This study allows the conclusion that the expression of bcl-2 is an early event in carcinogenesis and that it is replaced by mutation of p53 as the neoplastic change progresses.
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PMID:[Expression of p53 and bcl-2 in colorectal adenomas and carcinomas]. 967 86

The E6 and E7 genes of HPV-16 or HPV-18 both are necessary for effective immortalization of primary human genital keratinocytes. To analyse the individual role of E6 and E7 genes in dysregulating cell growth, we cloned the HPV-16 E6, E7 and E6/E7 genes into retroviruses. Primary human keratinocytes (PHK) were then infected with these retroviruses and selected in differentiation-inducing medium (high calcium and serum). The E6/E7 retroviruses were the most effective at inducing differentiation-resistant colonies. Intermediate numbers of colonies were induced by E6 and low numbers by E7. Interestingly, only cultures infected with E7 and E6/E7 retroviruses showed a significant proportion of cells progressing into the S phase, consistent with our earlier studies showing that E7 is required for the efficient immortalization of genital keratinocytes. Accompanying this entry into S phase, the E7 or E6/E7 transduced cells expressed high levels of cyclins A, B and E, but lower levels of cyclin D. In addition, cdc-2, cdk-2 and cdk-4 were also increased. No significant differences were detected in the expression of c-myc and c-fos between the vector and any of the transduced cells. Keratinocytes infected with the E7 retrovirus exhibited decreased levels of Rb protein and increased levels of p53, whereas cells infected with E6-expressing retroviruses displayed normal levels of Rb protein and decreased levels of p53. Finally, E7 induced a three-fold increase in bcl-2 expression. Our results indicate that the HPV-16 E7 gene alone is sufficient to bypass keratinoctye growth arrest induced by serum and calcium exposure and that the discordant expression of several cell regulatory proteins accompanies this unregulated proliferation.
Carcinogenesis 1998 Aug
PMID:HPV-16 E7 protein bypasses keratinocyte growth inhibition by serum and calcium. 974 46

Apoptosis, or programmed cell death, is an essential process for normal embryonic development, maintaining homeostasis in adult tissues, and suppressing carcinogenesis. The bcl-2 protein, discovered in association with follicular lymphoma, plays a prominent role in controlling apoptosis and enhancing cell survival in response to diverse apoptotic stimuli. The evolutionarily conserved bcl-2 protein is now recognized as being a member of a family of related proteins which can be categorized as death agonists or death antagonists. Progress in defining the role of bcl-2 and its family members in regulating apoptosis is rapidly advancing. This review describes, in detail, current bcl-2 family members and the possible mechanisms of function which allow the bcl-2 family of proteins to either promote or suppress cell death.
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PMID:The Bcl-2 gene family and apoptosis. 975 41

The proto-oncogene bcl-2, which is implicated in the regulation of cell death by inhibiting apoptosis, is reported to be expressed in breast tissues. The wild-type p53 has been shown to induce apoptosis, which can be inhibited by bcl-2 expression. However, the role of bcl-2 and p53 expression in breast carcinogenesis has not been clarified. The purpose of this study was to evaluate bcl-2 and p53 expression in normal breast epithelia cells, as well as in intraductal and invasive cancerous lesions of breast cancer tissue using an immunohistochemical method and to clarify their role in the development of breast cancer. The nuclear accumulation of p53 was also evaluated by quantitative image analysis. Expression of bcl-2 was found in 79 of 82 (96%) normal ductal epithelial cells, in 50 of 63 (79%) intraductal carcinomas, and in 62 of 137 (45%) invasive carcinomas, respectively. Higher bcl-2 expression was observed in normal epithelial cells than in intraductal and invasive cancerous cells (P < 0.0001). Furthermore, bcl-2 positivity in intraductal lesions was significantly higher than in invasive cancerous lesions (P < 0.05). No p53 nuclear accumulation was observed in normal breast epithelial cells. Fifteen of 63 (23.8%) intraductal cancerous lesions and 41 of 137 (30%) invasive cancerous lesions were positive for p53 expression. An inverse relationship was shown between bcl-2 and p53 expression in invasive carcinomas. We demonstrated that bcl-2 expression exists in most of normal ductal epithelial cells and gradually decreases during the development of breast cancer, i.e. , from a normal epithelium to intraductal carcinoma, and from intraductal to invasive carcinoma, and that p53 expression may occur early in breast cancer development and increases during progression.
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PMID:Correlation between the expression of apoptosis-related bcl-2 and p53 oncoproteins and the carcinogenesis and progression of breast carcinomas. 981 31

A disturbance in the balance between cell proliferation and cell loss, or apoptosis, may underlie neoplastic development. Therefore, we determined spontaneous apoptotic and proliferative rates in normal, hyperplastic, adenomatous, and malignant colorectal epithelia. In paired sections, DNA strand breaks were detected using the terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling assay, and apoptotic cells were also identified in H&E-stained slides by morphological criteria. Cell proliferation, bcl-2, and p53 expression were analyzed using specific monoclonal antibodies. In normal mucosa, luminal epithelial cells demonstrated higher rates of apoptosis compared to cells in the proliferative zone. Neoplastic transformation was associated with a significant increase in rates of apoptosis and proliferation. However, apoptosis, but not proliferation, decreased at the adenoma-to-carcinoma transition coincident with expression of mutant p53. In carcinomas, both mutant p53 and bcl-2 protein levels were associated with attenuated apoptotic rates. In conclusion, apoptosis is an important regulator of growth in normal and neoplastic colorectal epithelia. Increased apoptosis and proliferation accompany neoplastic transformation, suggesting that an alteration in apoptotic rates is an important event in colorectal carcinogenesis. Furthermore, the imbalance in these processes found in carcinomas may facilitate tumor growth and progression.
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PMID:Increased apoptosis accompanies neoplastic development in the human colorectum. 981 59

Apoptosis-related genes have received increasing attention in carcinogenesis, drug sensitivity, radiation sensitivity, and patient survival. bcl-2 and mutated p53 genes have been reported to inhibit apoptosis. To determine bcl-2 and p53 protein expression and their impacts on survival time in lung cancers, we studied 99 surgically resected, paraffin-embedded non-small cell lung cancer (NSCLC) specimens by immunohistochemical staining. The bcl-2 protein was expressed in 19.2% of NSCLCs. bcl-2-positive cases were found in 30. 4% of stages I and II carcinomas in 36.8% of squamous cell carcinomas. Patients with bcl-2 expression survived longer than those without. p53 protein was found in 44.4%; there was no significant difference in survival time between patients with and without p53 expression. Patients who were both bcl-2 positive and p53 negative survived significantly longer than those who were bcl-2 negative or p53 positive. These results suggest that bcl-2 protein expression can be histologically specific and stage dependent, and that the bcl-2 protein expression is potentially valuable for prognosis in NSCLC, particularly in the early stages, when bcl-2 protein expression is considered with mutant p53 protein expression.
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PMID:bcl-2 and p53 protein expression in non-small cell lung cancers: correlation with survival time. 981 50

To investigate the regulation of apoptosis and proliferation in arsenic-induced skin cancers, we examined the expression of bcl-2, p53, and Ki-67 using immunohistochemical staining. Thirty patients with Bowen's disease (BD), ten with basal cell carcinoma (BCC), eight with squamous cell carcinoma (SCC) and eleven of perilesional normal skin (PLN) of the non-sun exposure sites from endemic area were examined. The results showed that: 1) bcl-2 was expressed in all of the BCC homogeneously, in none of the SCC, and in 12/30 of the BD focally or homogeneously; 2) p53 was expressed in all of the arsenical skin cancers with a labelling index of 75 +/- 14% of BD, 50 +/- 17% of BCC, 61 +/- 15% of SCC, and also in all of the perilesional normal skin with a labelling index of 55 +/- 24%; 3) Ki-67 was expressed in all of the skin cancers with labelling index of 58 +/- 17% of BD, 12 +/- 7% of BCC, 47 +/- 21% of SCC, and in 9/11 of PLN with a labelling index of 41 +/- 24%. Expression of bcl-2 in BCC or BD is related to the phenotype of germinative basal cell. The constant expression of bcl-2 i early dysplastic cells of BD and the earliest expression of P53 in the basal cells of perilesional normal skin indicate that the initial step of arsenic-induced carcinogenesis is from the basal germinative cells. There is no mutual relationship between bcl-2, p53 or Ki-67 expression in any type of the arsenical skin cancers, but there is a positive correlation between p53 and Ki-67 expression identified in perilesional normal skin. BD had the highest labelling index of p53 and Ki-67.
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PMID:Expression of bcl-2, p53 and Ki-67 in arsenical skin cancers. 982 Oct 74

In the development of a cancer, unlimited cell proliferation has been believed to play an important role. In addition, a programmed cell death called apoptosis, which is regulated by several oncogenes and tumor suppressor genes, has been suggested to be another important different pathway of carcinogenesis. Recently, several reports on cell proliferation capacity and apoptosis in the development of human liver disease have been published, but the cell proliferation index and its relationship between the expression of the bcl-2 and p53 genes involving apoptosis has not yet been discussed in view of the clinical differences of primary and metastatic liver cancer. In this study, we investigated the cell proliferation index and expression of p53 and bcl-2 in the tumorous and non-tumorous portions of both hepatocellular carcinoma and metastatic liver cancer. The expression of p53 was observed in both hepatocellular carcinoma and metastatic liver cancer, but bcl-2 expression was observed neither in hepatocellular carcinoma nor in metastatic liver cancer. In hepatocellular carcinoma, the p53 positive group showed a higher Ki-67 score (cell proliferation index) and more tumor numbers than the p53 negative group (p < 0.05). In metastatic liver cancer, the results were the same as in hepatocellular carcinoma (p < 0.05). However, we could not correlate the p53 expression and its prognostic significance in hepatocellular carcinoma.
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PMID:Cell proliferation index and the expression of p53 and Bcl-2 in tumorous and non-tumorous lesions of hepatocellular carcinoma and metastatic liver cancer. 982 91

Sustained, increased cell proliferation induced by dietary zinc deficiency in rats plays a critical role in esophageal carcinogenesis. It is the determining factor that converts an otherwise nontumorigenic dose of N-nitrosomethylbenzylamine (NMBA) into a highly tumorigenic one. We studied whether the increased esophageal cell proliferation and susceptibility to NMBA-induced carcinogenesis induced by zinc deficiency can be inhibited by alpha-difluoromethylornithine (DFMO), an enzyme-activated, irreversible inhibitor of ornithine decarboxylase (the first enzyme in polyamine synthesis). Weanling rats were divided into four groups: Zn+/DFMO-, Zn+/DFMO+, Zn-/DFMO-, and Zn-/DFMO+. They were fed ad libitum either a zinc-sufficient (Zn+, 75 ppm zinc) or a zinc-deficient (Zn-, 4 ppm zinc) diet and given either deionized water (DFMO-) or 1% DFMO in deionized water (DFMO+). After 5 weeks, 5-19 animals from each group were sacrificed after in vivo 5-bromo-2'-deoxyuridine labeling to detect cells in S phase. The remaining animals in each group were given a single intragastric dose of NMBA at 2 mg/kg and sacrificed 12 weeks later for tumor incidence analysis. At week 5, DFMO treatment greatly decreased (by 48-82%) the levels of putrescine and spermidine in rat esophagus, colon, and liver, irrespective of dietary zinc intake. The increased esophageal cell proliferation induced by dietary zinc deficiency, as measured by the labeling index, the number of labeled cells, and the total number of cells, was substantially reduced by DFMO. This was accompanied by an increase in the rate of apoptosis. In addition, the expression of bax protein, an apoptosis accelerator, was markedly stronger in esophagi from Zn-/DFMO+ animals that showed increased apoptosis, whereas increased expression of bcl-2, an inhibitor of apoptosis, was only seen in the highly proliferative, zinc-deficient esophagus (Zn-/DFMO-). At week 12 after NMBA dosing, DFMO reduced the incidence of esophageal tumors from 80 to 4% in zinc-deficient rats. Our data showed that DFMO effectively inhibited the increased esophageal cell proliferation induced by dietary zinc deficiency and reduced the incidence of esophageal tumors induced by a single dose of NMBA in zinc-deficient animals. Our results also indicate a role for increased apoptosis in the mechanism(s) whereby DFMO brings about the inhibition of cell proliferation and tumor induction. These findings support a role for DFMO as a chemopreventive agent.
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PMID:Alpha-difluoromethylornithine inhibits N-nitrosomethylbenzylamine-induced esophageal carcinogenesis in zinc-deficient rats: effects on esophageal cell proliferation and apoptosis. 985 69


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