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Query: UNIPROT:P04637 (p53)
 77,613 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cervical cancer is not considered a hormone-responsive tumor in spite of the presence of estrogen receptors (ER) and progesterone receptors (PgR) in some of them. Endocrine treatments have not achieved clinical responses, however, tamoxifen has been reported to induce PgR and to inhibit cell growth of many cervical carcinoma cell lines. In this study we investigated whether tamoxifen administration affects the histopathological characteristics of cervical cancer and the expression of ER, PgR, HER-2/neu and p53 protein. Nineteen patients with invasive cervical cancer free of previous treatments were studied. The triphenylethylene antiestrogen tamoxifen was given orally during 10 days (20 or 40 mg/day). Pre- and post-tamoxifen biopsies were evaluated using slides stained with hematoxylin and eosin and immunostained (ER, PgR, HER-2/neu, p53, PCNA, keratin, heat shock protein 27,000 daltons). Estrogen receptors were present in 37% and PgR in 16% of the biopsies from untreated patients. Only one case that was PgR-negative before tamoxifen administration showed weak PgR-positivity following antiestrogen administration. No obvious changes were observed in ER, HER-2/neu and p53 proteins. A statistically significant decrease in the number of mitotic figures was obtained in 16% (3/19) of the post-tamoxifen biopsies and two of them showed higher differentiation. The results showed that tamoxifen did not induce changes in estrogen-regulated proteins in cervical cancer. However, the data showed that certain cervical carcinomas had changes in their proliferation and differentiation levels following tamoxifen administration. These findings suggest that tamoxifen may affect some cervical cancer tissues by a hormone-independent mechanism(s).
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PMID:Effects of short-term tamoxifen administration in patients with invasive cervical carcinoma. 790 50

Human papillomaviruses (HPVs) contribute to the development of benign and malignant cervical cancer; however, the exact role of papillomaviruses in the multistage carcinogenesis process is unclear. The development of HPV-immortalized cervical and foreskin cell lines represents a useful model for studying the role of HPVs in cervical cancer. Studies with these cells show that HPV genes regulate epithelial cell growth and differentiation. Transfection of HPV types associated with invasive cervical cancer results in immortalization of human epithelial cells, whereas HPVs not associated with cancer are ineffective. The combination of E6 and E7 genes, which are normally retained and expressed in cervical carcinomas, is sufficient for immortalization; however, the E7 gene alone induces immortality less efficiently. Although the immortalized cells actively express HPV oncoproteins observed in cervical cancer, after injection of immortal cells into nude mice, tumors are rare, having been reported only for HPV-18. Immortalized cells are resistant to terminal differentiation; in fact, HPVs may contribute to the carcinogenic process by uncoupling the processes of cell growth and differentiation. Host regulation of viral genes also is important in the malignant process. Endogenous cytokines modify HPV gene expression and influence the pathogenesis of HPV infection in the cervix. HPV gene expression is regulated by cellular transcriptional activators and repressors. This normal regulation is altered by viral integration. HPVs become integrated preferentially at chromosomal regions near fragile sites and protooncogenes. In fact, immortality is associated with induction of structural rearrangements frequently affecting HPV integration sites. Structural and numerical alterations nonrandomly involve chromosomes 1, 11, 19, and 20, with chromosome 1 alteration being the most predominant. Wild-type functions of Rb and p53 are necessary to control normal cell growth, and mutation or loss of these suppressor genes often contributes to cancer development. In HPV-containing carcinomas, pRb and p53 were wild type. However, in carcinomas lacking HPV, both suppressor genes were mutated. Functional inactivation of these tumor suppressor genes by HPV oncoproteins E6 and E7 may explain this difference. Treatment of HPV-immortalized cells with ras or a subfragment of herpes simplex virus (HSV) of HPV-immortalized cells resulted in locally invasive carcinomas when the cells were implanted subcutaneously in nude mice. These experiments indicate that HPV integration and expression are insufficient for malignancy but that HPVs do participate in the multistep development of cancer.
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PMID:Cellular and molecular alterations in human epithelial cells transformed by recombinant human papillomavirus DNA. 839 44

Cervical cancer develops from well-defined precursor lesions referred to as either cervical intraepithelial neoplasia or squamous intraepithelial lesions. It is now known that specific types of human papillomaviruses (HPV) are the principal etiologic agents for both cervical cancer and its precursors. The high-oncogenic-risk HPV types associated with invasive cervical cancer produce two oncoproteins, designated E6 and E7, which interact with endogenous cell cycle regulatory proteins, including p53 and Rb. The interaction of virally derived and endogenous cellular proteins converges in deregulation of cell cycle progression and appears to be critical for the development of cervical cancers. However, the development of cervical cancer is a multistep process that cannot be explained simply by infection with specific types of HPV. One additional event that appears to play a role in tumor progression is integration of HPV DNA into the host genome. Integration of HPV DNA frequently disrupts the E2 open reading frames, resulting in overexpression of the E6 and E7 oncoproteins and possibly causing genomic instability. Additional cofactors and mutational events may be important in the pathogenesis of invasive cervical cancers and may include chromosomal rearrangements, loss of constitutional heterozygosity, and proto-oncogene activation.
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PMID:Molecular biology of cervical cancer and its precursors. 863 81

Cervical cancer is the second leading cause of death from cancer in women worldwide, and recent epidemiological studies have strongly implicated the sexually transmitted human papillomavirus (HPV) as a causative agent. The ability of high-risk HPVs to contribute to malignant progression seems to depend on expression of the viral E6 and E7 oncogenes. The E6 oncoprotein forms a complex with the cellular tumor suppressor protein p53, leading to degradation of p53 via ubiquitin-dependent proteolysis. Thus, E6 expression results in the loss of p53 function in cells, including stimulation of apoptosis and inhibition of the expression of the antiapoptotic protein bcl-2. Recently, we found increased bcl-2 expression in cervical carcinoma cell lines containing mutated or E6-inactivated p53 (X. L. Liang, S. Mungal, A. Ayscue, J. D. Meissner, P. Wodnicki, G. Gordon, S. Lockett, and B. Herman. J. Cell. Biochem., 57: 509-520, 1995). Based on these findings, we examined Papanicolaou smears from 94 women with varying degrees of cervical disease for the presence or absence of p53, HPV-16/18 E6, and bcl-2 proteins using immunofluorescence microscopy. Our findings indicate that there is a statistically significant, inverse association between the presence of p53 and invasive cervical disease [odds ratio (OR), 0.3; 95% confidence interval (CI), 0.1-0.7]. Moreover, the odds of being diagnosed with an invasive stage of cervical cancer were 3.7 times higher (95% CI, 1.6-8.8) for women positive for the E6 protein and 17 times higher (95% CI, 5.5-58.3) for women positive for the bcl-2 protein compared with women negative for E6 and bcl-2. Women with invasive cervical cancer were also 4.59 times more likely to test positive for the presence of more than one marker (95% CI, 1.8-11.8). Chi(2) analysis demonstrated a strong association between the presence of E6 and bcl-2 (P < 0.001) as well as between the presence of E6 of bcl-2 and diagnosis (P = 0.015 and < 0.001, respectively). In the multivariate analysis, the presence of bcl-2 (OR, 18.8; 95% CI, 5.5-67.8) and age at diagnosis (> or = 50 years; OR, 7.8; 95% CI, 2.5-24.5) showed significant association with Invasive cervical disease. These findings indicate that: (a) the presence of the bcl-2 protein is strongly associated with the development of invasive cervical disease: (b) the pattern of the presence of high-risk HPV-E6, p53, and bcl-2 proteins may be useful for identifying women at increased risk for the development of invasive cervical cancer; and (c) a defect in apoptosis may partially underlie the development of cervical cancer.
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PMID:The presence of human papillomavirus-16/-18 E6, p53, and Bcl-2 protein in cervicovaginal smears from patients with invasive cervical cancer. 916 97

Worldwide, cancer of the cervix is the second leading cause of cancer death in women: each year, an estimated 500,000 cases are newly diagnosed. Among populations, there are large differences in incidence rates of invasive cervical cancer: these reflect the influence of environmental factors, screening Papanicolaou (Pap) tests, and treatment of pre-invasive lesions. The high-risk human papillomavirus (HPV) subtypes 16, 18, 31, 33, and 51 have been recovered from more than 95% of cervical cancers. We have made great strides in understanding the molecular mechanism of oncogenesis of this virus, focusing on the action of the E6 and E7 viral oncoproteins. These oncoproteins function by inactivating cell cycle regulators p53 and retinoblastoma (Rb), thus providing the initial event in progression to malignancy. Cervical cancers develop from precursor lesions, which are termed squamous intraepithelial lesions (SIL) and are graded as high or low, depending on the degree of disruption of epithelial differentiation. Viral production occurs in low-grade lesions and is restricted to basal cells. In carcinomas, viral DNA is found integrated into the host genome, but no viral production is seen. The well-defined pre-invasive stages, as well as the viral factors involved at the molecular level, make cervical carcinoma a good model for investigating immune therapeutic alternatives or adjuvants to standard treatments.
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PMID:Epidemiology and biology of cervical cancer. 1022 96

Squamous intraepithelial lesions (SIL) and invasive cancer of the uterine cervix are thought to be a series of lesions derived from normal cervical squamous tissue. Infection by high risk human papillomavirus (HPV) and integration of viral DNA may initially lead normal cervical cells to become pre-malignant cells in SIL and result in cervical malignancies later on. High risk HPVs, including types 16 and 18, produce a viral protein, E6, which is required for viral replication in host cells. The E6 protein is able to bind to host p53 causing inactivation of its function through the mechanism of ubiquitin-dependent degradation. It has recently been reported that the extent of p53 dysfunction caused by HPVs depends on the status of a polymorphism at codon 72 of p53, Pro or Arg. In that study, it was demonstrated that a patient homozygous for the Arg allele had about a seven times higher risk of developing cervical cancer than a patient homozygous for Pro. In an attempt to confirm this result and elucidate whether this allelic deviation of the Arg genotype seen in invasive cervical cancer occurs in the pre-malignant lesion SIL, we analyzed 219 SIL and 101 invasive cancer samples from Japanese patients using a PCR-based assay. Samples from 88 SIL and 76 invasive cancers were identified as HPV-infected samples and used for further analyses. In these, the frequencies of Arg homozygotes were 31.8, 33.0 and 36.8% in controls, SIL and invasive cancer, respectively. The distributions of the different alleles of codon 72 (Pro/Pro, Pro/Arg and Arg/Arg) did not show significant differences between either control and SIL groups or control and invasive cancer groups. Also, no difference in the frequency of Arg/Arg genotype was detected even between the control and HSIL groups or control and invasive cancer infected with high risk HPVs groups. In conclusion, there was no obvious relationship between the Arg genotype at codon 72 of p53 and predisposition to HPV-associated cervical neoplasia.
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PMID:Codon 72 polymorphism of p53 as a risk factor for patients with human papillomavirus-associated squamous intraepithelial lesions and invasive cancer of the uterine cervix. 1046 18

Viruses are etiologically linked to approximately 20% of all malignancies worldwide. Retroviruses account for approximately 8%-10% of the total. For human T-cell leukemia virus 1 (HTLV-I), the viral regulatory tax gene product is responsible for enhanced transcription of viral and cellular genes that promote cell growth by stimulating various growth factors and through dysregulation of cellular regulatory suppressor genes, such as p53. After a long latent period, adult T-cell leukemia/lymphoma (ATL) occurs in 1 per 1000 carriers per year, resulting in 2500-3000 cases per year worldwide and over half of the adult lymphoid malignancies in endemic areas. Human immunodeficiency virus 1 (HIV-1) accounts for a significant cancer burden, and its transactivating regulatory protein Tat enhances direct and indirect cytokine and immunological dysregulation to cause diverse cancers. Kaposi's sarcoma (KS) is a very rare tumor except after HIV-1 infection, when its incidence is greatly amplified reaching seventy thousand-fold in HIV-infected homosexual men. Human herpesvirus 8 (HHV-8), which is also known as Kaposi's sarcoma-associated virus (KSHV), is a necessary but not sufficient etiological factor in KS. The dramatic decline of KS since the introduction of highly active antiretroviral therapy (HAART) could be due to suppression of HIV-1 tat. B-cell non-Hodgkin's lymphoma occurs as their first acquired immunodeficiency syndrome-defining diagnosis in 3%-4% of HIV-infected patients. Hodgkin's lymphoma is also associated with HIV infection but at a lower risk. Human papillomaviruses are linked to invasive cervical cancer and anogenital cancers among HIV-infected patients. Human retroviruses cause malignancy via direct effects as well as through interactions with other oncogenic herpesviruses and other viruses.
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PMID:Human retroviruses: their role in cancer. 1059 Oct 85

A. Storey et al. [Nature (Lond.), 393: 229-234, 1998)] reported a 7-fold increased risk of cervical cancer associated with having an Arg/Arg polymorphism at codon 72 of p53 compared with the Pro/Arg heterozygotes (odds ratio, 7.4; 95% confidence interval, 2.1-29.4). Complementary in vitro studies suggested that the HPV E6 oncoprotein more readily targets the arginine form, as opposed to the proline form, of p53 for degradation. We investigated the impact of this polymorphism in a population-based case-control study of invasive cervical cancer. Using a PCR assay to detect the p53 codon 72 polymorphism, we tested blood samples from 111 women with invasive squamous cell cancer of the cervix identified by a population-based registry and 164 random-digit telephone-dialed controls. The distribution of the genotype among control women was 38% heterozygous, 7% proline homozygous, and 55% arginine homozygous, and among the cases was 38%, 6%, and 56%, respectively. There was no increased risk of squamous cell invasive cervical cancer associated with homozygosity for the arginine allele (odds ratio, 1.0; 95% confidence interval, 0.6-1.7). Furthermore, there was no modification of this result by human papillomavirus (HPV) DNA status of the tumor, age, or smoking status. Among controls, there was no association between the polymorphism and HPV-16 L1 seropositivity. However, among case subjects, the codon 72 polymorphism may be related to HPV 16L1 seropositivity status.
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PMID:The p53 Arg72Pro polymorphism, human papillomavirus, and invasive squamous cell cervical cancer. 1069 87

P53 allelic polymorphism at codon 72 has been studied as a possible predisposing factor for cervical carcinogenesis with inconsistent results. Storey and colleagues recently published the interesting finding of a 7-fold increased risk for cervical cancer in women homozygous for the arginine allele at codon 72. This stimulated a number of independent investigations, the majority of which found no association of cervical cancer and arginine homozygosity. With the use of a modified Storey method for determining codon 72 allelotypes, DNA was examined from 431 microdissected, formalin-fixed, archival cervical conization specimens ranging from low-grade squamous lesions to invasive cancer. An alternative independent method using restriction fragment length polymorphism analysis was performed on all arginine homozygotes and all indeterminate cases for confirmation and final allelotype assignment. With the use of Storey's method alone, logistic regression suggested an association (odds ratio, 1.42) between arginine homozygosity and invasive disease. However, with the use of the combined method for accurate allelotyping, this trend disappeared (odds ratio, 1.00), the discordance was clearly resolvable as being due to methodologic variables. With the use of two separate methods for codon 72 allelotyping and accounting for a number of the issues raised in previously published reports, there is no increased risk for invasive cervical cancer associated with arginine homozygosity at codon 72 of p53.
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PMID:Polymorphism at codon 72 of p53 is not associated with cervical cancer risk. 1078 2

A case-control study was performed to investigate the risk of cervical cancer associated with p53 polymorphism at codon 72, encoding either arginine or proline. It has been recently suggested that the arginine isoform increases the susceptibility to invasive cervical cancer; however, data remain controversial. The polymorphism was examined by both allele-specific PCR and RFLP analysis in 101 patients with primary cervical cancer and in 140 healthy women of the same age and from the same geographical area. The distribution of p53 genotypes in cervical cancer patients and in controls was not significantly different (P = 0.445), and homozygosity for arginine at residue 72 was not associated with an increased risk for cervical cancer (odds ratio, 0.81; 95% confidence interval, 0.47-1.42; P = 0.52). Similarly, different genotype distribution and increased risk were not observed when patients versus controls were analyzed according to human papillomavirus status and cancer histotype. Therefore, no evidence of association between homozygosity for p53 arginine and cervical cancer was found in our population sample.
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PMID:p53 codon 72 polymorphism does not affect the risk of cervical cancer in patients from northern Italy. 1079 89


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