P53 mutations in colorectal cancer from northern Iran: Relationships with site of tumor origin, microsatellite instability and K-ras mutations

Five P53 SNPs Involved in Low Rectal Cancer Risk and Prognosis in a Chinese Population

Although the impact and potential mechanisms of p53 polymorphisms on human malignancies have been intensively studied, analyses for association between p53 polymorphisms and colorectal cancer (CRC) risk were still limited to some common variants. Moreover, the majority of previous studies did not classify the specimens of CRC based on tumor location. This case-control study aimed to evaluate the association of five p53 polymorphisms (rs1042522, rs12947788, rs1625895, rs2909430 and rs12951053) with the risk of low rectal cancer (LRC) and investigate the prognostic significance. A total of 347 cases and 353 controls from a Chinese population were recruited and genotyped using KASP assay. Individuals carrying the variant rs12947788 A allele were observed to associate with an increased risk of LRC. After stratification for clinicopathological parameters, rs12947788 was significantly co-related with the histological type of LRC under a dominant model. Although none of the selected p53 polymorphisms was significantly associated with patient prognosis in total population, significant associations with the overall survival were revealed in the heterozygosis carriers vs. wild type carriers model through subgroup analyses based on clinical characteristics. Moreover, haplotype analyses showed that C-A-G-A-A haplotype was associated with a significantly higher LRC risk as compared to the other haplotypes. In low rectal cancer, P53 protein expression was obviously higher in p53 rs1042522 mutant carriers than in other genotypes. Our study further proves the involvement of p53 polymorphisms in pathogenesis of LRC and may provide potential therapeutic implications.

Targeted exome sequencing reveals distinct pathogenic variants in Iranians with colorectal cancer

PURPOSE

Next Generation Sequencing (NGS) is currently used to establish mutational profiles in many multigene diseases such as colorectal cancer (CRC), which is on the rise in many parts of the developing World including, Iran. Little is known about its genetic hallmarks in these populations.

AIM

To identify variants in 15 CRC-associated genes in patients of Iranian descent.

RESULTS

There were 51 validated variants distributed on 12 genes: 22% MSH3 (n = 11/51), 10% MSH6 (n = 5/51), 8% AMER1 (n = 4/51), 20% APC (n = 10/51), 2% BRAF (n = 1/51), 2% KRAS (n = 1/51), 12% PIK3CA (n = 6/51), 8% TGFβR2A (n = 4/51), 2% SMAD4 (n = 1/51), 4% SOX9 (n = 2/51), 6% TCF7L2 (n = 3/51), and 6% TP53 (n = 3/51). Most known and distinct variants were in mismatch repair genes (MMR, 32%) and APC (20%). Among oncogenes, PIK3CA was the top target (12%).

MATERIALS AND METHODS

CRC specimens from 63 Shirazi patients were used to establish the variant' profile on an Ion Torrent platform by targeted exome sequencing. To rule-out technical artifacts, the variants were validated in 13 of these samples using an Illumina NGS platform. Validated variants were annotated and compared to variants from publically available databases. An in-silico functional analysis was performed. MSI status of the analyzed samples was established.

CONCLUSION

These results illustrate for the first time CRC mutational profile in Iranian patients. MSH3, MSH6, APC and PIK3CA genes seem to play a bigger role in the path to cancer in this population. These findings will potentially lead to informed genetic diagnosis protocol and targeted therapeutic strategies.

Molecular Characterization of Somatic Alterations in Dukes' B and C Colorectal Cancers by Targeted Sequencing

Despite global progress in research, improved screening and refined treatment strategies, colorectal cancer (CRC) remains as the third most common malignancy. As each type of cancer is different and exhibits unique alteration patterns, identifying and characterizing gene alterations in CRC that may serve as biomarkers might help to improve diagnosis, prognosis and predict potential response to therapy. With the emergence of next generation sequencing technologies (NGS), it is now possible to extensively and rapidly identify the gene profile of individual tumors. In this study, we aimed to identify actionable somatic alterations in Dukes’ B and C in CRC via NGS. Targeted sequencing of 409 cancer-related genes using the Ion Ampliseq^TM Comprehensive Cancer Panel was performed on genomic DNA obtained from paired fresh frozen tissues, cancer and normal, of Dukes’ B (n = 10) and Dukes’ C (n = 9) CRC. The sequencing results were analyzed using Torrent Suite, annotated using ANNOVAR and validated using Sanger sequencing. A total of 141 somatic non-synonymous sequence variations were identified in 86 genes. Among these, 64 variants (45%) were predicted to be deleterious, 38 variants (27%) possibly deleterious while the other 39 variants (28%) have low or neutral protein impact. Seventeen genes have alterations with frequencies of ≥10% in the patient cohort and with 14 overlapped genes in both Dukes’ B and C. The adenomatous polyposis coli gene (APC) was the most frequently altered gene in both groups (n = 6 in Dukes’ B and C). In addition, TP53 was more frequently altered in Dukes’ C (n = 7) compared to Dukes’ B (n = 4). Ten variants in APC, namely p.R283^∗, p.N778fs, p.R805^∗, p.Y935fs, p.E941fs, p.E1057^∗, p.I1401fs, p.Q1378^∗, p.E1379^∗, and p.A1485fs were predicted to be driver variants. APC remains as the most frequently altered gene in the intermediate stages of CRC. Wnt signaling pathway is the major affected pathway followed by P53, RAS, TGF-β, and PI3K signaling. We reported the alteration profiles in each of the patient which has the potential to affect the clinical decision. We believe that this study will add further to the understanding of CRC molecular landscape.

Colorectal cancer in iran: molecular epidemiology and screening strategies

Purpose. The increasing incidence of colorectal cancer (CRC) in the past three decades in Iran has made it a major public health burden. This study aimed to report its epidemiologic features, molecular genetic aspects, survival, heredity, and screening pattern in Iran. Methods. A comprehensive literature review was conducted to identify the relevant published articles. We used medical subject headings, including colorectal cancer, molecular genetics, KRAS and BRAF mutations, screening, survival, epidemiologic study, and Iran. Results. Age standardized incidence rate of Iranian CRCs was 11.6 and 10.5 for men and women, respectively. Overall five-year survival rate was 41%, and the proportion of CRC among the younger age group was higher than that of western countries. Depending on ethnicity, geographical region, dietary, and genetic predisposition, mutation genes were considerably diverse and distinct among CRCs across Iran. The high occurrence of CRC in records of relatives of CRC patients showed that family history of CRC was more common among young CRCs. Conclusion. Appropriate screening strategies for CRC which is amenable to early detection through screening, especially in relatives of CRCs, should be considered as the first step in CRC screening programs.

Characterization and Prognostic Value of Mutations in Exons 5 and 6 of the p53 Gene in Patients with Colorectal Cancers in Central Iran

BACKGROUND/AIMS

We aimed to investigate the relation-ships among various mutations of the p53 gene and their protein products, histological characteristics, and disease prognosis of primary colorectal cancer in Isfahan, central Iran.

METHODS

Sixty-one patients with colorectal adenocarcinoma were enrolled in the study. Mutations of the p53 gene were detected by single-stranded conformation polymorphism and DNA sequencing. The protein stability was evaluated by immunohistochemistry. Patients were followed up to 48 months.

RESULTS

Twenty-one point mutations in exons 5 and 6 were detected in the tumor specimens of 14 patients (23%). Of those, 81% and 9.5% were missense and nonsense mutations, respectively. There were also two novel mutations in the intronic region between exons 5 and 6. In 11 mutated specimens, protein stability and protein accumulation were identified. There was a relationship between the type of mutation and protein accumulation in exons 5 and 6 of the p53 gene. The presence of the mutation was associated with an advanced stage of cancer (trend, p<0.009). Patients with mutated p53 genes had significantly lower survival rates than those with wild type p53 genes (p<0.01).

CONCLUSIONS

Mutations in exons 5 and 6 of the p53 gene are common genetic alterations in colorectal adenocarcinoma in central Iran and are associated with a poor prognosis of the disease.

Prevalence of TP53 germ line mutations in young Pakistani breast cancer patients

Women from Pakistan and India are more often diagnosed with early-onset breast cancer than Caucasian women. Given that only 12% of Pakistani women diagnosed with breast cancer at or before 30 years of age have previously been shown to harbor germ line mutations in the breast cancer susceptibility genes BRCA1 and BRCA2, the genetic causes of the majority of early-onset cases are unexplained. Since germ line mutations in the tumor suppressor gene TP53 predispose women to early-onset breast cancer, we assessed the prevalence of TP53 mutations in 105 early-onset breast cancer patients from Pakistan, who had previously been found to be negative for BRCA1 and BRCA2 germ line mutations. The patient group included 67 women diagnosed with early-onset breast cancer at or before age 30 with no family history of breast or ovarian cancer (EO30NFH group) and 38 women diagnosed with breast cancer at or before age 40 with one or more first- or second-degree relatives with breast or ovarian cancer (EO40FH group). Mutation analysis of the complete TP53 coding region was performed using denaturing high-performance liquid chromatography analysis, followed by DNA sequencing of variant fragments. One deleterious mutation, c.499-500delCA in exon 5, was identified in the 105 breast cancer patients (1%). This mutation is novel in the germ line and has not been described in other populations. It was detected in a 28-year-old patient with no family history of breast or ovarian cancer. This mutation is rare as it was not detected in additional 157 recently recruited non-BRCA1 and non-BRCA2-associated early-onset breast cancer patients. Our findings show that TP53 mutations may account for a minimal portion of early-onset breast cancer in Pakistan.

Alterations of MEN1 and E-cadherin/β-catenin complex in sporadic pulmonary carcinoids

Pulmonary carcinoids, distinct in typical and atypical, represent 2–5% of all primary lung tumors. The aim of this study was to investigate the molecular alterations correlated with the development of this form of neoplasms. A collection of 38 paraffin-embedded apparently sporadic carcinoids was investigated, through a combined study, for protein expression/localization of menin, p53, β-catenin and E-cadherin and for mutational analysis of the MEN1, TP53 and CTNNB1 genes. Menin was expressed in 71% of cases, with a prevalent cytoplasmic (c) localization, β-catenin was expressed in 68.4% of cases, of which 36.8% with a membranous (m) and 31.6% with a cytoplasmic localization. Membranous E-cadherin immunoreactivity was detected in 84.2% cases, nuclear p53 expression in 5.3% of cases. Positive correlation was found between c-menin and c-β-catenin expression (rho=0.439, P=0.008). In addition, m-β-catenin showed a positive correlation with both c-β-catenin and E-cadherin expression (rho=0.380, P=0.022 and rho=0.360, P=0.040, respectively). With regard to the E-cadherin/β-catenin complex, we found also a significant positive correlation between c-menin and ‘disarrayed’ β-catenin expression (rho=0.481, P= 0.007). MEN1 gene variants were characterized in 34% of cases. c-menin was more highly expressed in tumors with MEN1 variants, compared to tumors without MEN1 variants (P=0.023). Three nucleotide variants of TP53 were also detected. This study confirms the involvement of the MEN1 gene in the development of sporadic pulmonary carcinoids, demonstrates the accumulation of menin in the cytoplasm, and indicates that the disarrayed pattern of the complex significantly correlates with c-menin accumulation.

DNA alterations of microsatellite DNA, p53, APC and K-ras in Chinese colorectal cancer patients

BACKGROUND

  Colorectal cancer is one of the most rapidly increasing cancers in the world, and accumulation of alterations in oncogenes, tumour suppressor genes and mismatch repair (MMR) genes contributes to colorectal tumorigenesis. Thus, we investigated the alterations of 14 microsatellite loci adjacent to MMR genes, p53, adenomatous polyposis coli (APC) and K-ras in 52 Chinese patients with colorectal cancer.

MATERIALS AND METHODS

  We performed fluorescent polymerase chain reaction and capillary electrophoresis to analyse microsatellite instability (MSI) and loss of heterozygosity (LOH) in microsatellite loci, which included a panel of nine dinucleotide repeats and the Bethesda consensus panel. Additionally, we screened for mutations in exons 4-9 of p53 and the mutation cluster region (MCR) in APC by DHPLC. Codons 12, 13 and 61 in K-ras were analysed using direct sequencing. All variations were confirmed using clone sequencing.

RESULTS

  The alteration frequency of microsatellite DNA was 55·8% (29/52). Among the microsatellites, five loci exhibited MSI and another nine loci exhibited LOH. The mutation rates of p53, APC and K-ras were 42·3%, 38·5% and 36·5%, respectively. All patients (n = 7) with liver metastasis had a mutation in p53, APC or K-ras. APC mutation was correlated with clinical stage and the presence of lymph node metastasis (P = 0·001 and P = 0·006, respectively). CONCLUSIONS>   A total of 80·8% of Chinese patients with colorectal cancer show variations in microsatellite DNA, p53, APC or K-ras. It appears that these microsatellite DNA alterations could be a new biomarker for colorectal cancer.

The insulin receptor substrate 1 (IRS1) in intestinal epithelial differentiation and in colorectal cancer

Colorectal cancer (CRC) is associated with lifestyle factors that affect insulin/IGF signaling, of which the insulin receptor substrate 1 (IRS1) is a key transducer. We investigated expression, localization and pathologic correlations of IRS1 in cancer-uninvolved colonic epithelium, primary CRCs with paired liver metastases and in vitro polarizing Caco2 and HT29 cells. IRS1 mRNA and protein resulted higher, relative to paired mucosa, in adenomas of familial adenomatous polyposis patients and in CRCs that overexpressed c-MYC, ß-catenin, InsRß, and IGF1R. Analysis of IRS1 immunostaining in 24 cases of primary CRC with paired colonic epithelium and hepatic metastasis showed that staining intensity was significantly higher in metastases relative to both primary CRC (P<0.01) and colonic epithelium (P<0.01). Primary and metastatic CRCs, compared to colonic epithelium, contained significantly higher numbers of IRS1-positive cells (P = 0.013 and P = 0.014, respectively). Pathologic correlations in 163 primary CRCs revealed that diffuse IRS1 staining was associated with tumors combining differentiated phenotype and aggressive markers (high Ki67, p53, and ß-catenin). In Caco 2 IRS1 and InsR were maximally expressed after polarization, while IGF1R was highest in pre-polarized cells. No nuclear IRS1 was detected, while, with polarization, phosphorylated IRS1 (pIRS1) shifted from the lateral to the apical plasma membrane and was expressed in surface cells only. In HT29, that carry mutations constitutively activating survival signaling, IRS1 and IGF1R decreased with polarization, while pIRS1 localized in nuclear spots throughout the course. Overall, these data provide evidence that IRS1 is modulated according to CRC differentiation, and support a role of IRS1 in CRC progression and liver metastatization.

p53 mutation is common in microsatellite stable, BRAF mutant colorectal cancers

The majority of "serrated pathway" colorectal cancers have mutation of the BRAF oncogene and display the CpG island methylator phenotype (CIMP). Half these cancers have microsatellite instability (MSI) and an excellent prognosis. In the absence of MSI (microsatellite stable, MSS), BRAF mutation has been associated with a particularly poor prognosis. "Traditional pathway" cancers are BRAF wild type. Mutation of p53 is common and this correlates with advanced stage. We therefore hypothesized that p53 mutation would be common in MSS/BRAF mutant colorectal cancer. One thousand and eighty-one colorectal cancers were screened for BRAF mutation to identify two BRAF mutant study groups (MSI: n = 77; MSS: n = 69) and a BRAF wild type control group (n = 101). These were screened for p53 mutation by high resolution melt analysis and classified for CIMP and MGMT methylation by quantitative methylation specific PCR. Molecular data were compared to patient age, gender, tumor location and stage. p53 was mutated significantly more frequently in MSS/BRAF mutant (28/69, 40.6%) compared to MSI/BRAF mutant cancers (13/77, 16.9%), but this mutation rate did not differ from MSS/BRAF wild type cancers (47/101, 46.5%)(p < 0.0001). CIMP was less common in MSS/BRAF mutant (26/47, 55.3%) compared to MSI/BRAF mutant cancers (41/54, 75.9%), but was more common than in MSS/BRAF wild type cancers (3/85, 3.5%) (p < 0.0001). MSS/BRAF mutant cancers were more commonly proximal (38/54, 70.3%), but were similar to MSS/BRAF wild type cancers in terms of patient age, gender distribution and stage at presentation. MSS/BRAF mutant cancers share molecular and clinical features of both the serrated and traditional pathways of colorectal tumorigenesis.

Study on TP53 codon 72 polymorphisms with oral carcinoma susceptibility

BACKGROUND AND AIMS

Previous published data have implicated TP53 codon 72 polymorphisms as risk factors for various cancers. Growing bodies of studies have been conducted on the association of TP53 codon 72 polymorphisms with susceptibility to oral carcinoma and have yielded inconclusive results. The aim of the present study was to derive a more precise estimation of this relationship.

METHODS

We conducted a search in the relevant databases without a language limitation, covering all papers published until May 2009. The associated literature was acquired through deliberate searching and selected based on the established inclusion criteria for publications.

RESULTS

Nine studies including 1990 cases and 2074 controls were selected. Data were extracted and further analyzed using systematic meta-analyses. Results showed that no significant differences of oral cancer risk were found between individuals carrying homozygote Arg/Arg genotype and those carrying Pro/Pro genotype (OR: 0.96, 95% CI: 0.78-1.19). Likewise, no evidence indicated that individuals with Arg/Arg genotype have a significant risk of oral cancer compared with those with a combined Pro genotype (Arg/Pro+Pro/Pro) (OR: 0.98, 95% CI: 0.85-1.12). Similarly, individuals with a combined Arg genotype (Arg/Pro+Arg/Arg) do not have a marked increased or decreased susceptibility to oral cancer relative to those with homozygote Pro/Pro genotype (OR: 1.00, 95% CI: 0.83-1.21). Moreover, when stratifying for race, results were similar among Asians or Caucasians. In addition, TP53 codon 72 polymorphisms may not associate with oral cancer risks in smokers and HPV infection status.

CONCLUSIONS

No evidence suggests that TP53 codon 72 polymorphisms may be a risk factor for oral carcinoma.

High-risk human papilloma virus infection, tumor pathophenotypes, and BRCA1/2 and TP53 status in juvenile breast cancer

Juvenile breast cancer is rare and poorly known. We studied a series of five breast cancer patients diagnosed within 25 years of age that included two adolescents, 12- and 15-years-old, and 3 young women, 21-, 21-, and 25-years-old, respectively. All cases were scanned for germline mutations along the entire BRCA1/2 coding sequences and TP53 exons 4-10, using protein truncation test, denaturing high performance liquid chromatography and direct sequencing. Paraffin-embedded primary tumors (available for 4/5 cases), and a distant metastasis (from the 15-years-old) were characterized for histological and molecular tumor subtype, human papilloma virus (HPV) types 16/18 E6 sequences and tumor-associated mutations in TP53 exons 5-8. A BRCA2 germline mutation (p.Ile2490Thr), previously reported in breast cancer and, as compound heterozygote, in Fanconi anemia, was identified in the 21-year-old patient diagnosed after pregnancy, negative for cancer family history. The tumor was not available for study. Only germline polymorphisms in BRCA1/2 and/or TP53 were detected in the other cases. The tumors of the 15- and 12-years-old were, respectively, classified as glycogen-rich carcinoma with triple negative subtype and as secretory carcinoma with basal subtype. The tumors of the 25-year-old and of the other 21-year-old were, respectively, diagnosed as infiltrating ductal carcinoma with luminal A subtype and as lobular carcinoma with luminal B subtype. No somatic TP53 mutations were found, but tumor-associated HPV 16 E6 sequences were retrieved from the 12- and 25-year-old, while both HPV 16 and HPV 18 E6 sequences were found in the tumor of the 15-year-old and in its associated metastasis. Blood from the 15- and 25-year-old, diagnosed with high-stage disease, resulted positive for HPV 16 E6. All the HPV-positive cases were homozygous for arginine at TP53 codon 72, a genotype associated with HPV-related cancer risk, and the tumors showed p16(INK4A) immunostaining, a marker of HPV-associated cancers. Notably menarche at 11 years was reported for the two adolescents, while the 25-year-old was diagnosed after pregnancy and breast-feeding. Our data suggest that high-risk HPV infection is involved in a subset of histopathologically heterogeneous juvenile breast carcinomas associated with menarche or pregnancy and breast-feeding. Furthermore we implicate BRCA2 in a juvenile breast carcinoma diagnosed at 21 years of age, 4 years after an early full-term pregnancy, in absence of cancer family history.

Transitions at CpG dinucleotides, geographic clustering of TP53 mutations and food availability patterns in colorectal cancer

BACKGROUND

Colorectal cancer is mainly attributed to diet, but the role exerted by foods remains unclear because involved factors are extremely complex. Geography substantially impacts on foods. Correlations between international variation in colorectal cancer-associated mutation patterns and food availabilities could highlight the influence of foods on colorectal mutagenesis.

METHODOLOGY

To test such hypothesis, we applied techniques based on hierarchical clustering, feature extraction and selection, and statistical pattern recognition to the analysis of 2,572 colorectal cancer-associated TP53 mutations from 12 countries/geographic areas. For food availabilities, we relied on data extracted from the Food Balance Sheets of the Food and Agriculture Organization of the United Nations. Dendrograms for mutation sites, mutation types and food patterns were constructed through Ward's hierarchical clustering algorithm and their stability was assessed evaluating silhouette values. Feature selection used entropy-based measures for similarity between clusterings, combined with principal component analysis by exhaustive and heuristic approaches.

CONCLUSION/SIGNIFICANCE

Mutations clustered in two major geographic groups, one including only Western countries, the other Asia and parts of Europe. This was determined by variation in the frequency of transitions at CpGs, the most common mutation type. Higher frequencies of transitions at CpGs in the cluster that included only Western countries mainly reflected higher frequencies of mutations at CpG codons 175, 248 and 273, the three major TP53 hotspots. Pearson's correlation scores, computed between the principal components of the datamatrices for mutation types, food availability and mutation sites, demonstrated statistically significant correlations between transitions at CpGs and both mutation sites and availabilities of meat, milk, sweeteners and animal fats, the energy-dense foods at the basis of "Western" diets. This is best explainable by differential exposure to nitrosative DNA damage due to foods that promote metabolic stress and chronic inflammation.

Polymorphisms of TP53 codon 72 with breast carcinoma risk: evidence from 12226 cases and 10782 controls

BACKGROUND

Previously, TP53 codon 72 polymorphisms have been implicated as risk factors for various cancers. A number of studies have conducted on the association of TP53 codon 72 polymorphisms with susceptibility to breast carcinoma and have yielded inconclusive results. The aim of the present study was to derive a more precise estimation of the relationship.

METHODS

We conducted a search in the Medline, EMBASE, OVID, Sciencedirect, and Chinese National Knowledge Infrastructure (CNKI) without a language limitation, covering all papers published up to Jan 2009. The associated literature was acquired through deliberate searching and selected based on the established inclusion criteria for publications.

RESULTS

A total of seventeen case-control studies, including 12226 cases and 10782 controls, met the included criteria and thus were selected. Ultimately, the relevant data were extracted and further analyzed using systematic meta-analyses. Overall, no associations of TP53 codon 72 polymorphisms with breast carcinoma were observed (for Arg/Arg vs Pro/Pro: OR = 1.20; 95%CI = 0.96-1.50; for dominant model: OR = 1.12; 95%CI = 0.96-1.32; for recessive model: OR = 1.13; 95%CI = 0.98-1.31). In the subgroup analysis by ethnicity, statistically similar results were obtained when the data were stratified as Asians, Caucasians and Africans.

CONCLUSION

Collectively, the results of the present study suggest that TP53 codon 72 polymorphisms might not be a low-penetrant risk factor for developing breast carcinoma.

Polymorphisms of TP53 codon 72 with prostate carcinoma risk: a meta-analysis

Previous published data indicated TP53 codon 72 polymorphisms as risk factors for various cancers. A large number of studies have been conducted on the association of TP53 codon 72 polymorphisms with susceptibility to prostate carcinoma and have yielded inconclusive results. The aim of the present study is to derive a more precise estimation of the relationship. We conducted a search in the Medline, EMBASE, OVID, Sciencedirect, and Chinese National Knowledge Infrastructure (CNKI) without a language limitation, covering all papers published up to Feb 2009. The associated literature was acquired through deliberate searching and selected based on the established inclusion criteria for publications. A total of six case-control studies, including 582 cases and 1075 controls, met the included criteria and thus were selected. Consequently, the relevant data were extracted and further analyzed using systematic meta-analyses. For the overall data, no associations of TP53 codon 72 polymorphisms with prostate carcinoma were observed (for Arg/Arg versus Pro/Pro: OR = 0.88; 95%CI = 0.62-1.25; for dominant model: OR = 1.05; 95%CI = 0.78-1.43; for recessive model: OR = 0.85; 95%CI = 0.67-1.06). In the subgroup analysis by ethnicity, individuals carrying Arg allele may have an increased susceptibility to prostate cancer compared with those carrying Pro allele in Caucasians. While for Asians, TP53 codon 72 polymorphism was unlikely to be a risk factor for prostate cancer. Moreover, TP53 codon 72 polymorphism seems to exert little effect on the metastasis and differentiation status of developing prostate carcinoma. Collectively, the results of the present study suggest that TP53 codon 72 polymorphism might be a low-penetrant risk factor for developing prostate carcinoma in Caucasians but not in Asians.

TP53 codon 72 polymorphism contributes to nasopharyngeal cancer susceptibility: a meta-analysis

BACKGROUND AND AIMS

Previously, TP53 codon 72 polymorphisms have been implicated as risk factors for various cancers. Several studies have been conducted on the association of TP53 codon 72 polymorphisms with susceptibility to nasopharyngeal carcinoma (NPC) and have yielded inconclusive results. The aim of the present study was to assess possible associations of NPC risk with TP53 codon 72 polymorphisms.

METHODS

We conducted a search in Medline, EMBASE, OVID, ScienceDirect, and Chinese National Knowledge Infrastructure (CNKI) without a language limitation, covering all papers published until November 2008. The associated literature was acquired through deliberate searching and selected based on the established inclusion criteria for publications.

RESULTS

Consequently, five studies including 394 cases and 606 controls met the included criteria and thus were selected. Ultimately, relevant data were extracted and further analyzed using systematic meta-analyses. The results showed that individuals carrying wild homozygote Arg/Arg genotype have a decreased risk of NPC compared with those carrying Pro/Pro genotype (OR: 0.46, 95% CI: 0.30-0.70). For Pro allele, no evidence indicated that individuals with a combined Pro genotype (Arg/Pro+Pro/Pro) have a significant risk of NPC compared with those with Arg/Arg genotype (OR: 0.81, 95% CI: 0.62-1.07). For Arg allele, individuals with a combined Arg genotype (Arg/Pro+Arg/Arg) have a marked decreased susceptibility to NPC relative to those with homozygote Pro/Pro genotype.

CONCLUSIONS

Results of the present study suggest that TP53 codon 72 polymorphisms may be a risk factor for NPC. Homozygote Pro/Pro genotype could significantly increase susceptibility to NPC, whereas Arg allele markedly decreases NPC risk.