Polymorphisms in codon 31 of p21 and cervical cancer susceptibility in Korean women

Polymorphism at codon 31 of CDKN1A (p21) as a predictive factor for bevacizumab therapy in glioblastoma multiforme

Glioblastoma (GBM), a prevalent and malignant brain tumor, poses a challenge in surgical resection due to its invasive nature within the brain parenchyma. CDKN1A (p21, Waf-1), a cyclin-dependent kinase inhibitor, plays a pivotal role in regulating cell growth arrest, terminal differentiation, and apoptosis. The existence of natural variants of CDKN1A has been associated with specific cancer types. In this retrospective study, our objective was to identify polymorphic variants of CDKN1A, specifically c.93C > A (codon 31 Ser31Arg), and investigate its potential impact within the scope of bevacizumab therapy for glioblastoma multiforme. This study involved a cohort of 139 unrelated adult Chinese GBM patients in Taiwan. Genomic DNA extracted from tumor samples was utilized for genotyping using the polymerase chain reaction (PCR) restriction fragment length polymorphism method (PCR-RFLP analysis). Through unconditional logistic regression analysis, odds ratios (ORs) with corresponding 95% confidence intervals (CIs) were calculated. Our findings unveiled that among these GBM patients, the distribution of codon 31 polymorphisms was as follows: 23.02% were Serine homozygotes (Ser/Ser), 27.34% were Arginine homozygotes (Arg/Arg), and 49.64% were Serine/Arginine heterozygotes (Ser/Arg). While CDKN1A c.93C > A polymorphisms did not exhibit a direct association with overall survival in GBM patients, noteworthy survival benefits emerged among individuals with Arg/Arg and Arg/Ser genotypes who received combined concurrent chemoradiotherapy (CCRT) and bevacizumab treatment compared to those who underwent CCRT alone. Our findings indicate a significant involvement of the CDKN1A c.93C > A polymorphism in the development and onset of GBM, offering potential implications for the early prognostication of bevacizumab therapy outcomes.

Effect of NBS1 Gene Polymorphism on the Risk of Cervix Carcinoma in a Northern Indian Population

Cervical cancer is one of the most common neoplastic diseases affecting women, with a worldwide incidence of almost half a million cases. A history of smoking and use of oral contraceptives have been confirmed to be risk factors for cervical cancer. Genetic susceptibility and immune response, especially impaired cellular immune response, may well be related to the development of cervical cancer. NBS1 is one of the key proteins participating in the recognition and repair of double-strand breaks that may lead to genomic instability and cancer if unrepaired. The objective of the present study was therefore to investigate NBS1 Glu185Gln gene polymorphisms and the risk of cervix cancer in a northern Indian population. We found that passive smokers having particular NBS1 genotypes (Glu/Gln, Gln/Gln or Glu/Gln + Gln/Gln) have an increased risk of developing cervix cancer (OR 5.21, p=0.000001; OR 4.60, p=0.001; OR 5.10, p=0.0000009, respectively). The risk was increased 2.4-fold in oral contraceptive users with a Glu/Gln genotype. We conclude that the risk of cervical cancer is increased in passive smokers and in users of oral contraceptives with certain NBS1 genotypes.

Association between p21 Ser31Arg polymorphism and the development of cervical lesion in women infected with high risk HPV

Infection by high-risk human papillomavirus (HR-HPV) and single nucleotide polymorphism (SNP) in genes involved in cell cycle control, as p21 and p27, are important factors in the development of different types of human cancers. This study aims at investigating whether both the p21 Ser31Arg and p27 V109G polymorphisms are associated with susceptibility to the development of cervical lesions in women HR-HPV positive. We analyzed 132 women HPV positive and with cervical lesions or CC and 154 healthy control (HPV negative and without cervical lesions). p21 Ser31Arg and p27 V109G polymorphisms were analyzed using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method and sequencing. The p21 31Arg allele was associated with susceptibility for the development of cervical lesions (P* = 0.0009), while p27 V109G polymorphism showed no significant differences for this association (P* = 0.89). However, the combined effect of the polymorphisms showed that the presence of the CC genotype (SNP p21 Ser31Arg) conferred protection for the development of cervical lesions (OR = 0.39). p21 Ser31Arg and p27 V109G polymorphisms were not associated with the grade of cervical lesions (CINI, CINII, and CINIII) or CC (P* > 0.05). The HR-HPV more frequent in this study were of 16 (57.6 %) and 18 (37.1 %) types; however, no association was observed when both polymorphisms and risk factors analyzed were compared (P* > 0.05). Our findings suggest a possible association between p21 Ser31tabArg polymorphism and susceptibility to the development of cervical lesions in women from Pernambuco. Brazil.

Roles of CDKN1A gene polymorphisms (rs1801270 and rs1059234) in the development of cervical neoplasia

The CDKN1A gene product is a p53 downstream effector, which participates in cell differentiation, development process, repair, apoptosis, senescence, migration, and tumorigenesis. The objective of our study was investigated the importance of two polymorphisms in the CDKN1A gene, rs1801270 (31C>A) and rs1059234 (70C>T), for the development of cervical lesions in a Southeastern Brazilian population (283 cases, stratified by lesion severity, and 189 controls). CDKN1A genotyping was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and/or DNA sequencing. CDKN1A 31A allele presents a genetic pattern of protection for the development of high-grade cervical lesions (CC vs CA genotype: OR = 0.60; 95 % CI = 0.38-0.95; p = 0.029; CA+AA vs CC genotype: OR = 0.60; 95 % CI = 0.39-0.93; p = 0.021). Allele distributions of the CDKN1A 70C>T polymorphism were also different between the two study groups, with the CDKN1A 70T allele being less prevalent among cases. Moreover, the double heterozygote genotype combination 31CA-70CT decreases the chance of developing high-grade squamous intraepithelial lesion (HSIL) and cancer (OR = 0.55; 95 % CI = 0.32-0.93; p = 0.034) by 50 %, representing a protective factor against the development of more severe cervical lesions.

Polymorphism at P21 codon 31 and dinucleotide polymorphism of P73 gene and susceptibility to bladder cancer in individuals from North India

BACKGROUND AND AIM:

p73, a novel P53 homolog and plays an important role in modulating cell cycle control, apoptosis and cell growth while P21, functions to negatively control the cell cycle. P53 up regulates p21 expression in response to deoxyribonucleic acid damage leading to cell cycle arrest at G1 checkpoint. In the present study, we are targeting p21 codon 31 and p73 gene variants of G4C14-to-A4T14 (Exon 2) polymorphism for bladder cancer (BC) risk in North Indians.

MATERIALS AND METHODS:

The above gene variants of P21 and P73 were assessed in the case-control study comprising of 200 BC cases and 200 healthy controls of the same age, gender and similar ethnicity. Genotyping was performed by polymerase chain reaction (PCR) restriction fragment length polymorphism method and PCR-based confronting two-pair primers (PCR with CTPP).

RESULTS:

The variant genotype of p73Exon 2 polymorphism showed significant risk for BC (p = 0.014). While combining with heterozygous genotype, variant genotype of p73Exon2 showed a significant association with BC risk (p = 0.010). While in case of p21 codon31 showed no significant association for BC risk at genotypic level. Significant association between p73Exon2 polymorphism and smoking was observed for BC risk. Furthermore, gene combination analysis revealed that AT/AT-Ser/Ser is associated with risk for BC. Variant genotype of P73Exon2 was associated with reduced risk of recurrence (p = 0.039) in superficial BC patients receiving Bacillus Calmette-Guerin treatment thus showing least survival (log rank = 0.029).

CONCLUSION:

Our study provided evidence that the p73 G4C14 > A4T14 (Exon2) polymorphisms were associated with higher risk of BC in North Indian population.

Aberrant promoter hypermethylation of p21 (WAF1/CIP1) gene and its impact on expression and role of polymorphism in the risk of breast cancer

p21 (Waf-1) is a cyclin-dependent kinase inhibitor that plays essential roles in cell growth arrest, terminal differentiation, and apoptosis. Statistically significant difference in the level of methylation of p21/CIP1 (p < 0. 05) between the patients with breast cancer and the healthy controls was observed. Risk of breast cancer was increased in patients with hypermethylated p21/CIP1 promoter by 2.31-fold (OR = 2.31, 95 % CI 1.95-2.74). The downregulation of p21/CIP1 mRNA expression was statistically significant in patients with methylated promoter (p < 0.00) in comparison to patients with unmethylated genes. Downregulation of mRNA expression of p21/CIP1 was up to 79% due to promoter hypermethylation. We examined several p21/CIP1 genotypes in the patients with breast cancer and found that there is no significant association of these p21/CIP1 genotypes with the risk of developing breast cancer. However, a significant 2.21-fold increase in the chance of developing breast cancer was observed in the candidates carrying at least one allele Arg mutant in p21/CIP1 genotype (i.e., Ser/Arg + Arg/Arg) with age >50 (OR = 2.21; 95 % CI 1.03-4.79).

Quantitative assessment of the relationship between p21 Ser31Arg polymorphism and cervical cancer

Though many studies were published to assess the relationship between p21 Ser31Arg polymorphism and cervical cancer, there was no definite conclusion on this association. To provide a quantitative assessment of the relationship between p21 Ser31Arg polymorphism and cervical cancer, we performed a meta-analysis of 10 eligible studies (1,539 cases and 2,161 controls). All those 10 studies were from Asians. The odds ratios (OR) with 95% confidence intervals (95%CIs) were used to assess the strength of the association, and the pooled ORs were calculated for the codominant model (ArgArg vs. SerSer), the dominant model (ArgArg/SerArg vs. SerSer), and the recessive model (ArgArg vs. SerSer/SerArg). Meta-analysis of those 10 studies showed that there was no association between p21 Ser31Arg polymorphism and cervical cancer risk in Asians under all three models (ArgArg vs. SerSer: OR = 1.04, 95%CI 0.66-1.65, P = 0.86, I(2) = 78%; ArgArg/SerArg vs. SerSer: OR = 0.93, 95%CI 0.66-1.30, P = 0.66, I(2) = 81%; ArgArg vs. SerSer/SerArg: OR = 1.20, 95%CI 0.84-1.73, P = 0.32, I(2) = 72%). Sensitivity analysis performed by omitting each study in turn showed that the pooled results were stable. In summary, there is no association between p21 Ser31Arg polymorphism and cervical cancer risk in Asians. Further studies are needed to assess the possible association between p21 Ser31Arg polymorphism and cervical cancer risk in Caucasians.

Association of MDM2 SNP309 and TP53 Arg72Pro polymorphisms with risk of endometrial cancer

The incidence of endometrial cancer, a common gynecological malignancy, is increasing in Japan. We have previously shown that the ER/MDM2/p53/p21 pathway plays an important role in endometrial carcinogenesis. In the present study, we investigated the effects of germline single nucleotide polymorphisms in murine double minute 2 (MDM2) SNP309, TP53 Arg72Pro, ESR1 PvuII and XbaI, and p21 codon 31 on endometrial cancer risk. We evaluated these polymorphisms in DNA samples from 125 endometrial cancer cases and 200 controls using polymerase chain reaction-based restriction fragment length polymorphism. The association of each genetic polymorphism with endometrial cancer was examined by the odds ratio and 95% confidence interval, which were obtained using logistic regression analysis. The SNP309 GG genotype non-significantly increased the risk of endometrial cancer. The 95% confidence interval for the GG genotype vs. the TT genotype of MDM2 SNP309 was 1.76 (0.93–3.30). Endometrial cancer was not associated with tested SNP genotypes for TP53, ESR1 and p21. The combination of SNP309 GG + TG and TP53 codon 72 Arg/Arg significantly increased endometrial cancer risk. The adjusted OR was 2.53 (95% confidence interval, 1.03–6.21) and P for the interaction was 0.04. This result was supported by in vitro data showing that endometrial cancer cell lines with the SNP309 G allele failed to show growth inhibition by treatment with RITA, which reduces p53-MDM2 binding. The presence of the SNP309 G allele and TP53 codon 72 Arg/Arg genotype is associated with an increased risk of endometrial cancer in Japanese women.

Association of p21 SNPs and risk of cervical cancer among Chinese women

Background

The p21 codon 31 single nucleotide polymorphism (SNP), rs1801270, has been linked to cervical cancer but with controversial results. The aims of this study were to investigate the role of p21 SNP-rs1801270 and other untested p21 SNPs in the risk of cervical cancer in a Chinese population.

Methods

We genotyped five p21 SNPs (rs762623, rs2395655, rs1801270, rs3176352, and rs1059234) using peripheral blood DNA from 393 cervical cancer patients and 434 controls.

Results

The frequency of the rs1801270 A allele in patients (0.421) was significantly lower than that in controls (0.494, p = 0.003). The frequency of the rs3176352 C allele in cases (0.319) was significantly lower than that in controls (0.417, p < 0.001).The allele frequency of other three p21 SNPs showed not statistically significantly different between patients and controls. The rs1801270 AA genotype was associated with a decreased risk for the development of cervical cancer (OR = 0.583, 95%CI: 0.399 - 0.853, P = 0.005). We observed that the three p21 SNPs (rs1801270, rs3176352, and rs1059234) was in linkage disequilibrium (LD) and thus haplotype analysis was performed. The AGT haplotype (which includes the rs1801270A allele) was the most frequent haplotype among all subjects, and both homozygosity and heterozygosity for the AGT haplotype provided a protective effect from development of cervical cancer.

Conclusions

We show an association between the p21 SNP rs1801270A allele and a decreased risk for cervical cancer in a population of Chinese women. The AGT haplotype formed by three p21 SNPs in LD (rs1801270, rs3176352 and rs1059234) also provided a protective effect in development of cervical cancer in this population.

Association of p21 Ser31Arg and p53 Arg72Pro polymorphisms with lung cancer risk in CAPUA study

BACKGROUND

The aim of this study was to investigate how Ser31Arg polymorphisms in p21 may modify lung cancer susceptibility. Because p21 is the major downstream mediator of p53, we analyzed the combined effect of two polymorphisms, p21 Ser31Arg and TP53 Arg72Pro, to elucidate whether polymorphic variants determine the risk of lung cancer.

METHODS

This was designed as a hospital-based case-control study, and included 675 cases and 675 control subjects matched by ethnicity, gender, and age. Genotypes were determined by polymerase chain reaction restriction fragment length polymorphism, and multivariate unconditional logistic regression was performed to analyze the results.

RESULTS

Subjects who carried the p21 Ser31Arg allele had a higher risk of lung cancer (adjusted odds ratio [OR] 1.38; 95% confidence interval [CI] 0.99-2.03). This risk was increased in men aged younger than 55 years (adjusted OR 2.35; 95% CI 1.00-5.51). Smokers had an increased risk of lung cancer (adjusted OR 2.23; 95% CI 1.24-4.02). Men younger than 55 years carrying risk alleles for both genes (p21 Ser31Arg and TP53 Arg72Pro) had an increased risk (adjusted OR 5.78; 95% CI 1.38-24.19), as did smokers with both risk alleles (adjusted OR 4.52; 95% CI 1.52-13.50).

CONCLUSION

The presence of both variant alleles increased the risk of developing lung cancer in men, particularly in smokers younger than 55 years.

A comprehensive review on host genetic susceptibility to human papillomavirus infection and progression to cervical cancer

Cervical cancer is the second most common cancer in women worldwide. This is caused by oncogenic types of human papillomavirus (HPV) infection. Although large numbers of young sexually active women get HPV-infected, only a small fraction develop cervical cancer. This points to different co-factors for regression of HPV infection or progression to cervical cancer. Host genetic factors play an important role in the outcome of such complex or multifactor diseases such as cervical cancer and are also known to regulate the rate of disease progression. The aim of this review is to compile the advances in the field of host genetics of cervical cancer. MEDLINE database was searched using the terms, ‘HPV’, ‘cervical’, ‘CIN’, ‘polymorphism(s)’, ‘cervical’+ *the name of the gene* and ‘HPV’+ *the name of the gene*. This review focuses on the major host genes reported to affect the progression to cervical cancer in HPV infected individuals.

Association between p21 Ser31Arg polymorphism and cancer risk: a meta-analysis

P21 (CDKN1A), a key cell cycle regulatory protein that governs cell cycle progression from G1 to S phase, can regulate cell proliferation, growth arrest, and apoptosis. The Ser31Arg polymorphism is located in the highly conserved region of p21 and may encode functionally distinct proteins. Although many epidemiological studies have been conducted to evaluate the association between the p21 Ser31Arg polymorphism and cancer risk, the findings remain conflicting. This meta-analysis with 33 077 cases and 45 013 controls from 44 published case-control studies showed that the variant homozygous 31Arg/Arg genotype was associated with an increased risk of numerous types of cancers in a random-effect model (homozygote comparison: OR = 1.17, 95% CI = 0.99 to 1.37, P = 0.0002 for the heterogeneity test; recessive model comparison: OR = 1.16, 95% CI = 1.01 to 1.33, P = 0.0001 for the heterogeneity test). Stratified analysis revealed that increased cancer risk associated with the 31Arg/Arg genotype remained significant in subgroups of colorectal cancer, estrogen-related cancer, Caucasians, population-based studies, studies with matching information or a larger sample size. Heterogeneity analysis showed that tumor type contributed to substantial between-study heterogeneity (recessive model comparison: Χ(2) = 21.83, df = 7, P = 0.003). The results from this large-sample sized meta-analysis suggest that the p21 31Arg/Arg genotype may serve as a potential marker for increased cancer risk.

P21 Ser31Arg Polymorphism and Cervical Cancer Risk: A Meta-Analysis

Background

Studies investigating the association between p21 genetic polymorphism Ser31Arg and cervical cancer (CC) risk report conflicting results. The aim of this study was to quantitatively summarize the evidence for p21 polymorphism and CC risk.

Methods

Two investigators independently searched the MEDLINE, Embase, CNKI, and Chinese Biomedicine databases. Summary odds ratios (ORs) and 95% confidence intervals (CIs) for p21 polymorphism and CC were calculated in a fixed effects model (the Mantel-Haenszel method) and a random effects model (the DerSimonian and Laird method) when appropriate. The pooled ORs were performed for codominant model (Arg/Arg vs Ser/Ser and Arg/Ser vs Ser/Ser), dominant model (Arg/Arg + Arg/Ser vs Ser/Ser), and recessive model (Arg/Arg vs Arg/Ser + Ser/Ser). Subgroup analyses were performed by country, matched controls, and Hardy-Weinberg equilibrium in the controls and study sample size.

Results

This meta-analysis included 10 case-control studies from an Asian population, which included 1415 CC cases and 1947 controls. Overall, the variant genotypes (Arg/Arg and Arg/Ser) of Ser31Arg were not associated with CC risk, when compared with the wild-type homozygote Ser/Ser (Arg/Arg vs Ser/Ser: OR, 1.30; 95% CI, 0.81-2.08; Arg/Ser vs Ser/Ser: OR, 1.06; 95% CI, 0.72-1.55). Similarly, no associations were found in the dominant and recessive models (dominant model: OR, 1.05; 95% CI, 0.73-1.51; recessive model: OR, 1.28; 95% CI, 0.86-1.90). Stratified analyses also detected no significant association in any subgroup, except among those studies from "other" country and those studies with controls deviated from Hardy-Weinberg equilibrium.

Conclusion

No association was found between the p21 polymorphism Arg31Ser and risk of CC among Asians. In the future, additional studies based on white and African American patients should be performed to re-evaluate the association.

MDM2 and CDKN1A gene polymorphisms and risk of Kaposi's sarcoma in African and Caucasian patients

A single-nucleotide polymorphism in the MDM2 promoter (SNP309; rs2279744) causes elevated transcription of this major negative regulator of p53 in several cancer types. We investigated MDM2 SNP309 and CDKN1A (p21/Waf1/Cip1) codon 31 (rs1801270) polymorphisms in 86 cases of cutaneous Kaposi's sarcoma (KS) from African and Caucasian patients, and 210 healthy controls. A significant increase of the MDM2 SNP309 T/G genotype was observed among classic KS cases (odds ratio 2.38, 95% confidence interval 1.0-5.5). Frequencies of CDKN1A codon 31 genotypes were not significantly different between cases and controls. The results suggest that the MDM2 SNP309 G allele may act as a susceptibility gene for the development of classic KS in Caucasian patients.

Role of p53 and p21 polymorphisms in the risk of cervical cancer among Chinese women

The objective of this study was to identify whether polymorphic variants of p53 at codon 72 and p21 at codon 31 were associated with increased risk for cervical cancer, either independently or jointly, among Chinese women from southern Han. We genotyped p53 codon 72 and p21 codon 31 polymorphisms of peripheral blood DNA from 104 cervical cancer patients and 160 controls. Genotyping was confirmed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and direct DNA sequencing. We observed an increased risk of cervical cancer associated with the p53 Arg/Arg (OR, 2.25; 95% CI, 1.11-4.54) or p21 Ser/Ser (OR, 2.09; 95% CI, 1.04-4.19) genotype, compared with the p53 Pro/Pro or p21 Arg/Arg genotype, respectively. In additional, interaction between these p53 and p21 polymorphisms increased the risk of cervical cancer in a multiplicative manner, with the OR being 3.96 (95% CI, 1.51-10.41) for subjects carrying both p53 Arg/Arg and p21 Ser/Ser genotypes. These findings suggest that there is a significant association between the genetic polymorphism of p53, p21, and the risk of cervical cancer among Chinese southern women, and there is a possible gene-gene interaction in the incidence of cervical cancer.

Single-nucleotide polymorphisms in the p53 signaling pathway

The p53 tumor suppressor pathway is central both in reducing cancer frequency in vertebrates and in mediating the response of commonly used cancer therapies. This article aims to summarize and discuss a large body of evidence suggesting that the p53 pathway harbors functional inherited single-nucleotide polymorphisms (SNPs) that affect p53 signaling in cells, resulting in differences in cancer risk and clinical outcome in humans. The insights gained through these studies into how the functional p53 pathway SNPs could help in the tailoring of cancer therapies to the individual are discussed. Moreover, recent work is discussed that suggests that many more functional p53 pathway SNPs are yet to be fully characterized and that a thorough analysis of the functional human genetics of this important tumor suppressor pathway is required.

Polymorphisms ofp53Arg72Pro,p73G4C14-to-A4T14 at Exon 2 andp21Ser31Arg and the risk of non-Hodgkin's Lymphoma in Japanese

We hypothesized that the polymorphisms in the two p53 family genes (p53 Arg72Pro and p73 G4C14-to-A4T14 at exon 2 (G4A)) and p21 Ser31Arg polymorphism might modulate the risk of non-Hodgkin's lymphoma, and conducted a hospital-based prevalent case control study at Aichi Cancer Center Hospital to clarify the association. Risk estimation for each genotype by the unconditional logistic model demonstrated the possible association between the p53 Pro72 allele and the risk of non-Hodgkin's lymphoma in Japanese population (OR = 1.59; 95% CI, 0.99-2.57, P = 0.057), although no other significant association was observed. The analyses of statistical interactions between these three polymorphisms (p73 G4A, p53 Arg72Pro and p21 Ser31Arg polymorphisms) revealed the marginally significant OR for interaction between p53 Arg72Pro and p73 G4A polymorphisms (OR = 2.54; 95% CI, 0.97 6.62, P = 0.057). When those without p53 Pro72 and p73 A4T14 alleles were defined as a reference, those with p53 Pro72 and p73 A4T14 alleles demonstrated a significantly higher OR (2.08; 95% CI, 1.11-3.90, P = 0.023). Further examination with a sufficiently larger population and other ethnicities are required to confirm our findings.

The nonsynonymous single-nucleotide polymorphisms in codon 31 of p21 gene and the susceptibility to cervical cancer in Chinese women

BACKGROUND

It was suggested that single-nucleotide polymorphisms in p21 codon 31 seem to be associated with a variety of human malignancies; very few studies have focused on the association between p21 codon 31 polymorphisms and cervical cancer. This study explored whether p21 codon 31 nonsynonymous single-nucleotide polymorphisms might be associated with an increased risk of cervical cancer development among Chinese women.

METHODS

Peripheral blood samples were obtained from patients with cervical cancer (n = 317) and healthy controls (n = 353) for detecting the biallelic polymorphisms at codon 31 of p21 gene by the mismatch amplification mutation assay-polymerase chain reaction. Cervix brush-off samples were obtained from patients with cervical squamous cell carcinoma (SCC) and controls for detection of high-risk human papillomavirus (HR-HPV).

RESULTS

The AGA (Arg) allele frequency in patients with cervical SCCs was significantly higher than that in controls. AGA/AGA and AGA/AGC genotypes were more frequently found in cervical SCCs than in controls. There was no significant difference of allele frequency or genotype distribution between cervical adenocarcinomas and controls, or between HR-HPV-positive and HR-HPV-negative groups.

CONCLUSIONS

p21 Codon 31 with AGA (Arg) allele is a genetic risk factor of cervical SCC, and the increased risk is probably not caused by increasing host susceptibility to HR-HPV infection.

Polymorphisms in cell cycle regulatory genes, urinary arsenic profile and urothelial carcinoma

INTRODUCTION

Polymorphisms in p53, p21 and CCND1 could regulate the progression of the cell cycle and might increase the susceptibility to inorganic arsenic-related cancer risk. The goal of our study was to evaluate the roles of cell cycle regulatory gene polymorphisms in the carcinogenesis of arsenic-related urothelial carcinoma (UC).

METHODS

A hospital-based case-controlled study was conducted to explore the relationships among the urinary arsenic profile, 8-hydroxydeoxyguanosine (8-OHdG) levels, p53 codon 72, p21 codon 31 and CCND1 G870A polymorphisms and UC risk. The urinary arsenic profile was determined using high-performance liquid chromatography (HPLC) and hydride generator-atomic absorption spectrometry (HG-AAS). 8-OHdG levels were measured by high-sensitivity enzyme-linked immunosorbent assay (ELISA) kits. Genotyping was conducted using polymerase chain reaction-restriction fragment length polymerase (PCR-RFLP).

RESULTS

Subjects carrying the p21 Arg/Arg genotype had an increased UC risk (age and gender adjusted OR=1.53; 95% CI, 1.02-2.29). However, there was no association of p53 or CCND1 polymorphisms with UC risk. Significant effects were observed in terms of a combination of the three gene polymorphisms and a cumulative exposure of cigarette smoking, along with the urinary arsenic profile on the UC risk. The higher total arsenic concentration, monomethylarsonic acid percentage (MMA%) and lower dimethylarsinic acid percentage (DMA%), possessed greater gene variant numbers, had a higher UC risk and revealed significant dose-response relationships. However, effects of urinary 8-OHdG levels combined with three gene polymorphisms did not seem to be important for UC risk.

CONCLUSIONS

The results showed that the variant genotype of p21 might be a predictor of inorganic arsenic-related UC risk.

Comprehensive assessment of P21 polymorphisms and lung cancer risk

The purpose of this study is to comprehensively evaluate potential functional polymorphisms in the P21 gene in relation to the risk of lung cancer. We first determined the frequencies of P21 polymorphisms in 27 healthy Koreans, and then examined three polymorphisms (-2266G > A, S31R, and IVS2 + 16G > C), based on their frequencies and haplotype-tagging status, in a case-control study. Individuals with at least one -2266A allele were at a significantly decreased risk of lung cancer compared with those harboring the -2266 GG genotype [adjusted odds ratio (OR) = 0.71, 95% confidence interval (CI) = 0.53-0.95, P = 0.02). The haplotypes (ht2-4) carrying 31R or IVS2 + 16C alleles were associated with a significantly decreased risk of lung cancer compared with the haplotype 31S/IVS2 + 16G, which carried wild-type alleles at both loci (adjusted OR = 0.65, 95% CI = 0.50-0.83, P = 0.007)]. When the -2266A allele and ht2-4 were considered to be protective alleles, the risk of lung cancer decreased in a dose-dependent manner as the number of protective alleles increased (P = 0.0002). These results suggest that a combined analysis of these three P21 polymorphisms might better predict the risk of lung cancer than the analysis of a single polymorphism.

Expression of human leukocyte antigen-G and its correlation with interleukin-10 expression in cervical carcinoma

OBJECTIVE

To determine human leukocyte antigen (HLA)-G and interleukin (IL)-10 expression and the relationship between HLA-G expression and clinicopathologic features in patients with cervical cancer.

METHOD

Tissue samples were obtained from 40 patients with cervical cancer and 15 control patients with a normal cervix. Quantitative real-time RT-PCR for mRNA and western blot analysis for protein expression were used.

RESULT

Both HLA-G and IL-10 mRNA expression in cervical cancer tissues was significantly greater than normal controls (P<0.001, P=0.005). Protein expression of HLA-G and IL-10 in the cancer group was also significantly greater than in the controls (P<0.001, P=0.021). There was an inverse relationship between FIGO stage and HLA-G mRNA expression (P=0.046).

CONCLUSION

HLA-G and IL-10 might play an important role in cancer progression of the cervix. High HLA-G mRNA expression may be related to early carcinogenesis since it was associated with early-stage cervical cancer.

Mutations and polymorphisms of thep21B transcript in breast cancer

p21(WAF1/CIP1), transcribed from the CDKN1A locus, plays a key role executing p53-induced growth arrest. The recent discovery that an alternative transcript, p21B, induces apoptosis, suggests an additional important function of this gene. Here, we report p21 and p21B mutation status in large cohorts of breast cancers and compare distributions of p21B polymorphisms in cancer patients to healthy controls. In 521 breast tumor samples analyzed, only one point mutation affecting the p21B protein was observed. No mutations were found when screening a panel of 20 established cell lines. A novel polymorphism, p21B(G128T) was identified. Haplotype analysis revealed no association between this variant and the previously identified p21B polymorphism p21B(T35C) or any of the known p21(WAF1/CIP1) polymorphisms. As previously reported for p21B(T35C), distribution of p21B(G128T) was similar among breast cancer patients and healthy controls (n = 691 and 1,015; incidence 6.1 vs. 4.8%; p = 0.273, respectively). No association between p21B(G128T) or p21B(T35C) and response to chemotherapy with an anthracycline-containing regimen or paclitaxel was recorded. Our findings do not suggest mutations or polymorphisms of p21B to play a major role with respect to either breast cancer risk or sensitivity towards chemotherapy.

The novel p21 polymorphism p21G251A is associated with locally advanced breast cancer

PURPOSE

p21 is a main effector of growth arrest induced by p53. In addition, a second transcript from the same gene (p21B) has been linked to apoptosis. We previously analyzed p21 status in breast cancer and reported two novel polymorphisms of the p21 gene. In the present study, we present a larger study designed to explore a possible association between these novel polymorphisms and breast cancer.

EXPERIMENTAL DESIGN

The p21/p21B polymorphisms were analyzed in 507 breast cancer patients and 1,017 healthy individuals using cDNA or genomic DNA from tumor and/or blood samples.

RESULTS

We detected five polymorphisms of the p21 gene. Three of these polymorphisms are earlier reported by others, whereas two were reported for the first time in a recent study by us. The presence of the A allele of the p21G251A polymorphism was observed more frequently among patients with primary stage III breast cancer (4.5%) compared with stage I and II tumors (1.5%) and healthy female controls (1.4%; P = 0.007, comparing the three groups; P = 0.0049 and P = 0.0057, comparing locally advanced to stage I/II and healthy controls, or to healthy controls alone, respectively). The allele frequencies of the remaining four polymorphisms were evenly distributed among patients and healthy individuals.

DISCUSSION

The finding of an association between locally advanced breast cancer and one particular polymorphism of the p21 gene suggests this polymorphism to be related to tumor behavior, including enhanced growth rate. If confirmed in other studies, this may add significant information to our understanding of the biology as well as of the clinical behaviour of locally advanced breast cancers.

Variant genotypes of CDKN1A and CDKN1B are associated with an increased risk of breast cancer in Chinese women

p21(Cip1) and p27(Kip1) are cyclin-dependent kinase inhibitors, which can arrest cell proliferation and serve as tumor suppressors. Reduced protein expression of p21(Cip1) and p27(Kip1) was frequently observed in a subset of cancers, including breast cancer. In this study, we hypothesized that genetic variants in CDKN1A (encode for p21(Cip1)) and CDKN1B (encode for p27(Kip1)) may modulate the risk of breast cancer. To test this hypothesis, we evaluated the associations of the polymorphisms of Ser31Arg and C+20T in CDKN1A and C-79T and Gly109Val in CDKN1B, as well as their combinations, with breast cancer risk in a case-control study of 368 breast cancer cases and 467 cancer-free controls in a Chinese population. We found that a significantly increased risk of breast cancer was associated with the variant genotypes of CDKN1B C-79T [adjusted OR = 1.43 (95% CI = 1.03-1.98) for -79TC/TT], compared with the -79CC genotype, but no associations were observed for other variant genotypes. However, the combined variant genotypes of the 4 loci were associated with a significantly increased breast cancer risk (adjusted OR = 1.49, 95% CI = 1.11-2.01 among subjects carrying 3 or more variant alleles), especially among premenopausal women (adjusted OR= 2.30, 95% CI = 1.45-3.66). Furthermore, in premenopausal women, this significant association remained unchanged, after including other individual risk factors in the multivariate logistic regression model, suggesting an independent role of CDKN1A and CDKN1B variants in breast cancer risk. Although the exact biological mechanism remains to be explored, our findings suggest possible involvement of CDKN1A and CDKN1B variants in the etiology of breast cancer. Further large and functional studies are needed to confirm our findings.

Polymorphisms in the p53 pathway

The p53 tumor suppressor gene continues to be distinguished as the most frequently mutated gene in human cancer; this gene can be found mutated in up to 50% of human tumors of diverse histological type. It is generally accepted that the ability of p53 to induce either growth arrest or programmed cell death in response to diverse stimuli underlies the powerful selection against this protein in the development of cancer. It is somewhat surprising, then, to find p53 and several target genes in this pathway containing polymorphisms that impair their function. The nature of these polymorphic variants, and the mechanism whereby they impair the function of the p53 pathway, are reviewed here-in. The impact of these polymorphisms on cancer risk and the efficacy of therapy are only now becoming unraveled. Of particular relevance in these efforts will be the generation of mouse models of polymorphic variants in p53 and its target genes. Equally important will be better-controlled human studies, where-in haplotypes for p53 (that is, combinations of different polymorphisms in the p53 gene) and for p53-target genes are taken into account, instead of analyses of single gene variants, which have largely predominated to date. Studies in both regards should shed light on an emerging area in cancer biology, the significance of inter-individual differences in genotype on cancer risk, prognosis, and the efficacy of cancer therapy.

TP53 and P21 polymorphisms: response to cisplatinum/paclitaxel-based chemotherapy in ovarian cancer

Ovarian cancer (OC) is the most lethal gynaecologic cancer and its standard treatment consists of platinum-based chemotherapy after cytoreductive surgery. The p53 protein plays a critical role on different cellular processes in response to DNA damage and it is responsible for transcriptional induction of the P21 gene. We have analysed 114 blood samples in order to investigate the effect of the TP53 codon 72 and the P21 3'UTR polymorphisms in response to cisplatinum/paclitaxel chemotherapy for OC treatment. The genotypes of the TP53 codon 72 and P21 3'UTR polymorphism were identified using AS-PCR and PCR-RFLP, respectively. Our results indicate that the TP53 P allele is associated with a worse prognosis (P=0.011) while P21 polymorphism genotypes did not reveal any statistically significant result (P>0.05). Furthermore, simultaneous carriers of the TP53 AA genotype and the P21 CC genotype demonstrate a longer progression-free interval (P=0.020). This study suggests that the characterisation of a genetic profile can contribute to the definition of a better chemotherapy treatment.

Association between TP53 and p21 genetic polymorphisms and acute side effects of radiotherapy in breast cancer patients

p53 and p21 play an important role in G1/S checkpoint control in response to ionizing radiation. Yet the genetic polymorphisms in these genes have not been investigated with respect to radiation toxicity in patients. We therefore assessed the association between TP53 Arg72Pro, p53PIN3 and p21 Ser31Arg polymorphisms and the risk of acute skin toxicity after radiotherapy in a prospective study of 446 female breast cancer patients (average age 60.3+/-9.0 years) receiving radiotherapy after breast conserving surgery. The p53PIN3 polymorphism was determined by standard PCR, and TP53 Arg72Pro and p21 Ser31Arg polymorphisms using melting point analysis of sequence-specific hybridization probes. The development of acute skin toxicity (moist desquamation) was modelled using Cox proportional hazards, accounting for cumulative biologically effective radiation dose. Overall, the development of acute skin toxicity, which presented in 77 patients, was not significantly associated with the polymorphisms studied. Risks were however differential by body mass index. Compared to non-carriers, TP53 72Pro carriers had a non-significantly decreased risk of acute skin toxicity in normal weight women (hazard ratio 0.46, 95% CI, 0.18-1.18) but not in overweight patients (hazard ratio 1.07, 95% CI, 0.61-1.89) (p(interaction) =0.14). Haplotype analysis for the TP53 polymorphisms suggested that effect modification by TP53 72Pro may differ according to the p53PIN3 allele (p(interaction)=0.06). Furthermore, in TP53 72Pro carriers with p21 Ser/Ser genotype, the occurrence of acute toxicity was reduced in normal weight but not overweight patients. In conclusion, the TP53 72Pro variant may be associated with the development of acute skin toxicity after radiotherapy in patients with normal weight. Large clinical studies are needed to clearly confirm this association.

Lack of evidence that proline homozygosity at codon 72 of p53 and rare arginine allele at codon 31 of p21, jointly mediate cervical cancer susceptibility among Indian women

OBJECTIVES

The objective of this study was to identify whether variants of p53Arg72Pro and p21Ser31Arg were associated with increased risk for cervical cancer (CaCx), either independently or jointly, among Indian women.

METHODS

Genotyping was done by PCR-RFLP using DNA from (i) 120 cervical biopsy tissues of squamous cell carcinoma of the cervix (of which 82 were HPV16/18 positive), and (ii) a total of 205 cytologically normal cervical scrapes (121 HPV-negative and 84 HPV16/18-positive samples, considered as discreet groups). Multiple logistic regression analyses were performed to examine additive or interactive effects of the two factors and for determining age-adjusted OR (95% CI) and P values.

RESULTS

The observed association of proline homozygosity at codon 72 of p53 with CaCx infection (Bhattacharya, P., Duttagupta, C., Sengupta, S. 2002.Proline homozygosity in codon 72 of p53: A risk genotype for Human Papillomavirus related cervical cancer in Indian women. Cancer Lett 188: 207-211) was retained among Indian women harboring HPV16/18 (OR(age-adjusted) = 3.76; 95% CI = 1.03-13.80; P = 0.04). Significant independent association was evident between the p21 arginine allele (rare allele with frequency of 0.1) at codon 31 and CaCx, compared to HPV-negative cytologically normal controls (OR(age-adjusted) = 2.01; 95% CI = 1.00-4.06; P = 0.05). The two risk factors jointly failed to show statistical interaction towards susceptibility to CaCx. The p21 arginine allele was significantly associated with CaCx in the p53 proline non-homozygous group of subjects (OR(age-adjusted) = 2.68; 95% CI: 1.21-5.91; P = 0.01), and specifically in the p53 heterozygous group (OR(age-adjusted) = 2.91; 95% CI = 1.12-7.56; P = 0.03).

CONCLUSIONS

p53 and p21 act in series in mediating cell cycle arrest. However, the two risk factors, p53 proline homozygosity and p21 arginine allele, although part of a common causal pathway, appear to act in a mutually exclusive manner.

Genetic polymorphisms of p21 are associated with risk of squamous cell carcinoma of the head and neck

The p21 (Waf1/Cip1/CDKN1A) protein regulates the transition from the G1 to the S phase and has an important role in modulating cell-cycle control, apoptosis and cell growth. Two polymorphisms of the p21 gene at codon 31 (p21 C98A, dbSNP rs1801270) and at the 3' untranslated region (p21 T70C, dbSNP rs1059234) may have an effect on the protein function and may thus play a role in the development of cancer. We hypothesized that these two p21 polymorphisms are associated with the risk of squamous cell carcinoma of the head and neck (SCCHN). We tested this hypothesis in a hospital-based case-control study of 712 patients newly diagnosed with SCCHN and 1222 cancer-free controls who were frequency-matched by age, sex and ethnicity. All subjects were non-Hispanic whites. Our results showed that the variant alleles and genotypes were more common among cases than among controls (P < 0.001 and P = 0.013 for p21C70T, and P < 0.001 and P = 0.035 for p21C98A, respectively). Compared with the p21 70CC genotype, there was a significantly greater risk of SCCHN associated with the variant p21 70TC [odds ratio (OR) = 1.47, 95% confidence interval (CI) = 1.12-1.93] and combined p21 70TC/TT (OR = 1.49, 95% CI = 1.14-1.95) genotypes. Similarly, compared with the p21 98CC genotype, there was also a significantly greater SCCHN risk associated with the variant p21 98AC (OR = 1.32, 95% CI = 1.00-1.73) and combined p21 98AC/AA (OR = 1.37, 95% CI = 1.05-1.79) genotypes. When these two polymorphisms were evaluated together by the number of risk alleles, there was a significant increase in SCCHN risk that was dependent on the number of risk alleles (P(trend) = 0.001). Our results suggest that the presence of these two p21 polymorphisms may be a marker of genetic susceptibility to SCCHN.

p53 Codon 72 and p21 Codon 31 Polymorphisms in Prostate Cancer

The tumor suppressor gene p53 and its downstream effector p21 are thought to play major roles in the development of human malignancy. Polymorphic variants of p53 at codon 72, and p21 at codon 31, have been found to be associated with cancer susceptibility, but few studies have investigated their effect on prostate cancer risk. In this case-control study, we investigated the association of p53 codon 72 and p21 codon 31 polymorphisms with prostate cancer risk in a Taiwanese population. In total, 200 patients with prostate cancer, 247 age-matched male controls, and 181 non–age-matched symptomatic benign prostatic hyperplasia (BPH; American Urological Association symptom score ≥ 8 and prostate volume &gt; 20 gm) recruited from two medical centers in southern Taiwan were genotyped. Overall, we found no significant association between p53 polymorphism and risk of prostate cancer. However, for p21 polymorphism, the frequencies of p21 Ser/Ser, Ser/Arg and Arg/Arg were 52 (26.0%), 85 (42.5%), 63 (31.5%) in case patients, 48 (26.5%), 82 (45.3%), 51 (28.2%) in BPH patients, and 76 (30.8%), 119 (48.2%), 52 (21.1%) in controls, respectively. Among the prostate cancer cases and controls, subjects with Arg/Arg genotype were found to have a 1.78-fold increased risk [95% confidence interval (CI), 1.06-3.01] of developing prostate cancer compared with those having the Ser/Ser genotype, after adjusting for other potential covariates. This significant association was slightly stronger [odds ratio (OR), 2.13; 95% CI, 1.16-3.92] in younger men (≤ 72 years; n = 99 and 126 for cases and controls, respectively) and correlated with localized disease stage (OR, 1.96; 95 % CI, 1.15-3.35) and moderately differentiated prostate cancer (OR, 2.04; 95% CI, 1.17-3.53). In addition, the Arg/Arg genotype was associated with BPH risk in those with large prostate volumes (&gt; 50 mL) compared with those having the Ser/Ser genotype [OR, 2.29; 95% CI, 1.07-4.98]. Our findings suggest that the p21 codon 31 polymorphism may be associated with the development of prostate enlargement and cancer.

Gene-gene and gene-environmental interactions of p53, p21, and IRF-1 polymorphisms in Korean women with cervix cancer

BACKGROUND

The aim of this study was to identify gene-gene and gene-environmental factors affecting cervix carcinogenesis in Korean women.

METHODS

We evaluated 530 subjects composed of 185 female cervix cancer patients and 345 normal healthy women. The single nucleotide polymorphisms (SNPs) of p53 codon 72, p21 codon 31, and interferon regulatory factor-1 (IRF-1) intron 6 were evaluated from extracted DNA of peripheral blood with an automatic DNA sequencer. The differences of each SNP, gene-gene and gene-environmental interactions between normal controls and patients were evaluated in the adjusted environmental background.

RESULTS

In the environmental aspect, the rate of cervix cancer increased in the women with a lower level of education, a younger age at first sexual intercourse and more childbearing. The women who had p53 (Arg/Arg), IRF-1 (T/T), and <6 years of education showed a 14.7-fold increased risk of cervix cancer compared to the women who had p53 ( approximately Pro), IRF-1 ( approximately C), and >15 years of education. The women who had p53 (Arg/Arg), p21 (Ser/Ser), and >3 children showed a 6.4-fold increased risk of cervix cancer compared to the women who had p53 ( approximately Pro), p21 ( approximately Arg), and no children. The women who had p53 (Arg/Arg), IRF-1 (T/T), and first sexual intercourse before 22 years old showed a 5.5-fold increased risk of cervix cancer compared to the women who had p53 ( approximately Pro), IRF-1 ( approximately C), and first sexual intercourse after 26 years old.

CONCLUSIONS

We found that the level of education, the age at first intercourse, and the number of children were independent risk factors in cervix carcinogenesis. The specific combinations of p53, p21, and IRF-1 gene-gene and gene-environmental interactions were significantly noted in the cervix carcinogenesis of Korean women.

Genetic polymorphisms of GSTM1, p21, p53 and HPV infection with cervical cancer in Korean women

OBJECTIVES

The aim of this study was to determine whether GSTM1 or GSTT1 might be associated with risk of cervical cancer development in Korean women. The multiplicative interaction of GSTM1 and GSTT1 genotype with p21, p53 polymorphism, and HPV genotype was also investigated.

METHODS

From 1997 to 1999, uterine cervical carcinoma was diagnosed in 215 Korean women at the Department of Obstetrics and Gynecology of Seoul National University Hospital. None of the women in the control groups (n = 98) had any evidence of cervical lesions, which were confirmed by Pap smear. Finally, 81 cases and 86 controls were genotyped for p21, p53, and GSTM1 and T1 and HPV infection. A multiplex PCR method was used for the genotyping of GSTM1 and GSTT1; direct sequencing for p53 codon 72, high-risk HPV, and PCR-RFLP (BsmAI) for p21 codon. The unconditional logistic regression analysis was used to calculate ORs and 95% CI.

RESULTS

Although the GSTM1 and GSTT1 genotype was not significantly associated with cervical cancer development for all women, the GSTM1 null genotype was significantly associated with an increased risk of cervical cancer development in women with high-risk HPV infection (OR = 2.9, 95% CI: 1.0-8.2). Although the frequency of overall GSTT1 null genotype was significantly lower in cervical carcinoma patients with high-risk HPV infection (OR = 0.3, 95% CI: 0.1-1.0), almost 2-fold increased risk was observed among women with GSTT1 null and Arg/Arg genotype (OR = 1.9, 95% CI: 0.7-5.4). Although the cervical cancer risk was 3.3-fold increased in women with null and Arg/Arg genotype compared to women with GSTM1 present and p21 Ser-containing genotype, there was no significant multiplicative interaction between GSTM1 and p21 (P for interaction = 0.785) or p53 (P for interaction = 0.815).

CONCLUSIONS

These findings suggest that the risk of cervical cancer may be related to GSTM1 genotype in women with high-risk HPV infection and that there is a possible gene-gene interaction in the incidence of cervical cancer.

Influences of lifestyle habits and p53 codon 72 and p21 codon 31 polymorphisms on gastric cancer risk in Taiwan

Influences of lifestyle habits and p53 codon 72 and p21 codon 31 polymorphisms on the risk for developing primary gastric cancer were examined in 89 gastric adenocarcinoma cases (51 males, 38 females) and 192 controls (106 males, 86 females) in a hospital-based, case-control study in Taiwan. In the final regression model, Helicobacter pylori infection and substance use (cigarette smoking, areca chewing) were significant predictors of risk for developing gastric cancer. Compared with subjects negative for H. pylori infection, positive subjects were 3.65-fold (95% CI = 2.07-6.42) more likely to develop gastric cancer. Compared with non-smokers or non-chewers, subjects with more than a 15 pack-year history or more than a 498 betel-year history (about 20 betel quids/day for 25 years) were 2.27- and 4.86-fold more at risk (95% CI = 1.06-4.84 and 1.20-19.74), respectively. Frequencies of arg/arg, arg/pro and pro/pro in p53 were 11 (12.4%), 53 (59.5%) and 25 (28.1%) in carcinoma cases and 40 (20.8%), 95 (49.5%) and 57 (29.7%) in control cases, respectively. Frequencies of arg/arg, ser/arg and ser/ser in p21 were 26 (29.2%), 36 (40.5%) and 27 (30.3%) in carcinoma cases and 49 (25.5%), 94 (49.0%) and 49 (25.5%) in control cases, respectively. Neither p53, nor p21 polymorphisms were significantly different in cases and controls ( P = 0.16 and P = 0.41, respectively). Results remained insignificant after dichotomizing with respect to cigarette smoking, areca chewing and H. pylori infection. In summary, our data indicate that in Taiwan, H. pylori infection, smoking and areca chewing are significant risk predictors for developing gastric cancer. p53 codon 72 and p21 codon 31 genotypes did not modify these risks.

Association between p21 codon 31 polymorphism and esophageal cancer risk in a Taiwanese population

P21, which regulates the cell growth cycle, is crucial for normal growth and differentiation. One polymorphism in the p21 codon 31 produces variant proteins with an amino acid change (serine (ser) or arginine (arg)). Although several epidemiologic studies have examined the effect of this polymorphism on cancer risk, the findings remain inconclusive, which has motivated us to evaluate the relationship between p21 codon 31 polymorphism and esophageal cancer risk. In this study, 128 cases of esophageal squamous cell carcinoma and 178 control cases from two hospitals in southern Taiwan were genotyped. Frequencies of arg/arg, arg/ser and ser/ser were 23 (18.0%), 62 (48.4%) and 43 (33.6%) in carcinoma cases and 51 (28.6%), 84 (47.2%) and 43 (24.2%) in control cases, respectively. After factoring out other potential contributing factors, patients with ser/ser or arg/ser were 2.17 times more at risk (95% CI=1.03-4.56) for developing esophageal cancer than those with arg/arg. Males (n=274) were found to have a slightly stronger association (adjusted OR=2.45; 95% CI=1.03-5.80). Although the sample size is relatively small, these findings suggest that a codon 31 polymorphism in p21 may be associated with the development of esophageal cancer.

High intensity ras signaling induces premature senescence by activating p38 pathway in primary human fibroblasts

Although oncogenic ras plays a pivotal role in neoplastic transformation, it triggers an anti-oncogenic defense mechanism known as premature senescence in normal cells. In this study, we investigated the induction of cellular responses by different expression levels of oncogenic ras in primary human fibroblasts. We found that a moderate, severalfold increase in ras expression promoted cell growth. Further elevation of ras expression initially enhanced proliferation but eventually induced p16INK4A expression and senescence. The induction of these opposing cellular responses by ras signals of different intensity was achieved through differential activation of the MAPK pathways that mediated these responses. Whereas moderate ras activities only stimulated the mitogenic MEK-ERK pathway, high intensity ras signals induced MEK and ERK to higher levels, leading to stimulation of the MKK3/6-p38 pathway, which had been shown previously to act downstream of Ras-MEK to trigger the senescence response. Thus, these studies have revealed a mechanism for the differential effects of ras on cell proliferation. Furthermore, moderate ras activity mediated transformation in cooperation with E6E7 and hTERT, suggesting that a moderate intensity ras signal can provide sufficient oncogenic activities for tumorigenesis. This result also implies that the ability of ras to promote proliferation and oncogenic transformation can be uncoupled with that to induce senescence in cell culture and that the development of tumors with relatively low ras activities may not need to acquire genetic alterations that bypass premature senescence.

Interleukin-10 promoter polymorphisms and cervical cancer risk in Korean women

The aims of this study were to determine whether polymorphisms of the interleukin (IL)-10 promoter might be associated with an increased risk of cervical cancer, and further whether systemic IL-10 concentration might be influenced by the genotypes in Korean women. Peripheral blood samples from patients with invasive cervical cancer (ICC, n=144) and non-cancer controls (NCC, n=179) were used to detect three biallelic IL-10 promoter polymorphisms at -1082, -819, and -592 sites by polymerase chain reaction-restriction fragment length polymorphism assay using MnlI, MaeIII and RsaI, respectively. The IL-10 serum concentration was measured with enzyme-linked immunosorbent assay. We compared the distribution of genotypes in both groups, evaluated the serum IL-10 level according to the genotypes, and analyzed the association of these polymorphisms with the risk of cervical cancer. The genotype at the -1082 site exhibited only the *A homozygote, and only two haplotypes were found in Korean women, one being -1082*A/-819*T/-592*A (ATA) and the other -1082*A/-819*C/-592*C (ACC). No association was found for IL-10 promoter polymorphisms among the ICC patients in comparison with the NCC subjects. The risk of cervical cancer was not increased in either genotype and the IL-10 serum concentration was not influenced by the genotypes in either group. Polymorphisms of the IL-10 promoter do not appear to be associated with cervical cancer risk or systemic IL-10 production in Korean women.

Associations between common polymorphisms in TP53 and p21WAF1/Cip1 and phenotypic features of breast cancer

The tumour suppressor gene TP53 and its downstream effector p21 are thought to play major roles in the development of breast cancer. We investigated three common sequence variants in TP53 and p21 for possible associations with the risk of breast cancer and with various phenotypic features of this disease. A total of 351 cases were available for study. Germline DNA obtained from female subjects of similar age but without cancer was used to estimate the TP53 and p21 genotype frequencies in a control population. A single nucleotide polymorphism in intron 2 of p21 was associated with slightly increased breast cancer risk (RR = 1.4, P = 0.011) and with well/moderately differentiated tumour histology (P = 0.029). The 16 bp insertion polymorphism in intron 3 of TP53 was associated with poor histological grade (OR = 2.3, P = 0.013) independently of other pathological features. The codon 31 polymorphism in p21 was strongly linked to negative progesterone receptor status (OR = 3.4, P = 0.0001), suggesting this variant may have functional significance for the progesterone signalling pathway in breast cancer. These results add to the growing body of evidence that genetic variants can influence not only the risk of breast cancer but also the disease phenotype.