p53 Arg72Pro Polymorphism Predicts Survival Outcome in Lung Cancer Patients in Indian Population

Genetic Variants in Interleukin-10 Gene Association with Susceptibility and Cervical Cancer Development: A Case Control Study

Objectives  Cervical cancer (CC) is one of the most destructive disease caused by persistent HPV infection which affects women worldwide, especially in developing countries. The genetic basis of host immune response especially cytokine function has been shown to influence CC susceptibility. Studies have demonstrated that IL-10 gene polymorphism have been associated with numerous malignancies, but in context to CC results were inconclusive. Though, aim of our study to investigate the association between IL-10 -1082A/G and -819C/T promoter polymorphism and CC susceptibility.

Material and Methods  This study comprised 192 women with CC and 200 controls. HPV detection was done by RT-PCR and genotyping was assessed through PCR-RFLP method. Serum concentration of IL-10 measured by ELISA.

Results  Women with AG and AG+GG genotypes of IL-10 -1082A/G had two-fold increased risk of CC [OR, 2.35 (95% CI, 1.54–3.58), p  = 0.005], [OR, 2.03 (95% CI, 1.36–3.04), p  = 0.0005] compared to controls. Women with G allele of -1082A/G polymorphism had linked with CC susceptibility [OR, 1.39 (95% CI, 1.02–1.88), p  = 0.036] compared to controls. No significant difference was found between patients and controls in the genotype or allele frequencies of IL–10 -819C/T polymorphism [OR, 1.00 (95% CI, 0.63–1.58), p  = 0.99]. The level of serum concentration of IL-10 was significantly higher in cases compared to controls.

Conclusion  These findings help to understand that polymorphism of IL-10 -1082A/G gene is associated with increased risk of CC development and can serve as a marker of genetic susceptibility to CC.

The cell cycle regulatory gene polymorphisms TP53 (rs1042522) and MDM2 (rs2279744) in lung cancer: a meta-analysis

Lung cancer is one of the most common types of cancer in the world. Although the mechanism of lung cancer is still unknown, a large number of studies have found a link between gene polymorphisms and the risk of lung cancer. The tumor suppressor p53 plays a crucial role in maintaining genomic stability and tumor prevention. MDM2 is a critical regulator of the p53 protein. Despite the importance of p53 pathway in cancer, data on the contribution of SNPs of TP53 (rs1042522) and MDM2 (rs2279744) to the development of lung cancer are very contradictory. A metaanalysis that collects quantitative data from individual studies and combines their results has the advantage of improving accuracy, providing reliable estimates, and resolving those issues in which studies on individual associations are not effective enough. The aim of this study was to determine whether the TP53 (rs1042522) and MDM2 (rs2279744) polymorphisms confer susceptibility to lung cancer. A meta-analysis was conducted on the associations between the TP53 (rs1042522) and MDM2 (rs2279744) polymorphisms and lung cancer. A total of 51 comparison studies including 25,366 patients and 25,239 controls were considered in this meta-analysis. The meta-analysis showed no association between lung cancer and MDM2 (rs2279744) under any model. A noteworthy association of TP53 (rs1042522) with susceptibility to lung cancer in overall pooled subjects was observed under three different models (allele contrast, homozygote contrast (additive) and dominant). Stratification by ethnicity indicated an association between the TP53 (rs1042522) and lung cancer in Asians and Caucasians. This meta-analysis demonstrates that the TP53 (rs1042522), but not MDM2 (rs2279744) polymorphism may confer susceptibility to lung cancer.

Association of TP53 Codon 72 Arg>Pro Polymorphism with Breast and Lung Cancer Risk in the South Asian Population: A Meta-Analysis

BACKGROUND

A transversion missense polymorphism of the TP53 tumor suppressor gene at the codon 72 codes proline instead of arginine causes an altered p53 protein expression and has been found to be associated with an elevated risk of various cancer; especially breast and lung cancer. As the previous case-control studies on the South Asian population have shown controversial results, we performed a meta-analysis to evaluate a precise estimation of the relationship between the TP53 Arg72Pro polymorphism with breast and lung cancer.

METHODS

A total of 12 related studies on the South Asian population have been included through comprehensive database searching. Six studies were selected for breast cancer meta-analysis involving 950 cases and 882 controls; the other six studies were for lung cancer meta-analysis including 975 cases and 1397 controls. The results have been determined by using the Review Manager (RevMan) 5.3. Additionally, the stability of our analysis was assessed by heterogeneity, publication bias analysis and sensitivity testing.

RESULTS

A significantly increased risk of breast cancer was found in Pro allele (Pro vs. Arg), co-dominant model 2 (Pro/Pro vs. Arg/Arg), dominant model (Pro/Pro + Arg/Pro vs. Arg/Arg). In case of lung cancer, significantly increased risk was found in the allele, co-dominant 1, co-dominant 2, co-dominant 3, dominant, and recessive models. No association with other genetic models with breast and lung cancer risk was found in the South Asian population.

CONCLUSIONS

Our results indicate that TP53 Arg72Pro polymorphism is a risk factor for the development of breast cancer and lung cancer in the South Asian population.

Association of 12 polymorphic variants conferring genetic risk to lung cancer in Indian population: An extensive meta-analysis

Candidate gene as well as genome-wide association studies identified several polymorphic variants to be associated with lung cancer worldwide including in India. However, contradictory results have failed to estimate the overall effect of the polymorphic variants on the disease. Textmining was conducted on PubMed following specific search strings to gather all the publications related to genetic association with lung cancer in India. Out of 211 PubMed hits only 30 studies were selected for meta-analysis following specific inclusion criteria. Heterogeneity between studies was calculated by Cochran's Q-test (P < 0.05) and heterogeneity index (I² ). Publication bias was visualized by funnel plots and Egger's regression test. For each variant, following a fixed-effect model, summary odds ratio (OR) along with 95% confidence interval (CI) was estimated. The meta-analysis revealed three polymorphic variants viz. 'deletion polymorphism (del1) (OR = 1.39, 95% CI = 1.03-1.87, P = 0.027) in GSTT1', 'deletion polymorphism (del2) (OR = 1.30, 95% CI = 1.01-1.67, P = 0.038) in GSTM1' and 'rs1048943 (OR = 1.98, 95% CI = 1.27-3.10, P = 0.002) in CYP1A1' to be associated with lung cancer. However, after multiple testing correction, only rs1048943 was found to be significantly associated (P value = 0.0321) with lung cancer. None of the polymorphic variants showed any evidence of heterogeneity between studies or of publication bias. Our meta-analysis revealed strong association of rs1048943 in CYP1A1, but a suggestive association of deletion polymorphisms in GSTT1 and GSTM1 with lung cancer, which provides a comprehensive insight on the overall effect of the polymorphic variants, reported in various case-control studies on Indian population, on the risk of lung cancer development. Environ. Mol. Mutagen. 58:688-700, 2017. © 2017 Wiley Periodicals, Inc.

Individual and combined effect of TP53, MDM2, MDM4, MTHFR, CCR5, and CASP8 gene polymorphisms in lung cancer

Lung cancer (LC) is the second common and with the highest mortality oncological disease. Specific biomarkers for its diagnostics, treatment, and prognosis are still under the investigations. Aim of our study was to evaluate the relationship between the polymorphisms of TP53 pathway genes TP53, MDM2, MDM4, the polymorphisms of HPV-associated genes MTHFR, CASP8, CCR5, and HPV infection with survival of LC patients. SNPs were genotyped using PCR-RFLP. qRT-PCR was used to detect, identify, and quantify HPV. No statistically significant differences were detected between individual SNPs and patient survival with stage I-IV LC. Cluster analysis of SNPs in genes MDM4 A/A, CCR5 wt/Δ32, MTHFR C/T, MDM2 T/T showed possible association with the worse survival. Patients who were diagnosed with C/T polymorphic variant of gene MTHFR tend not to survive stage III-IV LC (P = .12). There is a tendency between MDM2 gene T/T variant and worse survival of patients diagnosed with late stage LC (P = .11). HPV infection is very rear among LC patients (3 of 92). Overall, there is a link, although statistically insignificant, between specific SNPs and LC patient survival frequency and time, meanwhile the combination of specific SNPs showed a statistically significant measure. In conclusion, we determined statistically significant (P = .04) link between the poor survival of LC patients after surgery and the combination of polymorphic variants C/T of the MTHFR and T/T of the MDM2 genes, whereas individually these SNPs do not show significant relationship with the survival of patients after surgery.

Mouse double minute-2 homolog (MDM2)-rs2279744 polymorphism associated with lung cancer risk in a Northeastern Chinese population

Background

Altered expression or function of mouse double minute-2 (MDM2) protein could contribute to lung carcinogenesis; thus, this study investigated MDM2-rs2279744 polymorphism together with other epidemiologic factors for their association with lung cancer risk.

Methods

A total of 500 lung cancer patients and 500 age and gender-matched healthy controls living in Northeastern China were recruited for genotyping of MDM2-rs2279744. Clinicopathological data was collected and subjected to univariate and multivariate analyses.

Results

In univariate analysis, the MDM2-rs2279744 G/G genotype versus T/T + T/G genotypes showed a tendency toward a higher incidence of lung cancer in the recessive model (P = 0.043). However, there were no significant differences when it was analyzed by the dominant, additive, or multiplicative models. A significantly increased lung cancer risk was observed associated with lower education level, lower body mass index, cancer family history, prior diagnosis of chronic obstructive pulmonary disease and pneumonia, exposure to pesticide or gasoline/diesel, tobacco smoking, and heavy cooking emissions when assessed by multivariate analyses. Moreover, MDM2-rs2279744 was still a significant risk factor even after incorporating environmental and lifestyle factors. However, there was no association between MDM2-rs2279744 and other factors.

Conclusions

The MDM2-rs2279744 G/G genotype was associated with a higher lung cancer risk, even after incorporating other epidemiologic factors.

Tumor suppressor miR-24 restrains gastric cancer progression by downregulating RegIV

BACKGROUND

microRNAs are small noncoding RNAs that modulate a variety of cellular processes by regulating multiple targets, which can promote or inhibit the development of malignant behaviors. Accumulating evidence suggests miR-24 plays important roles in human carcinogenesis. However, its precise biological role remains largely elusive. This study examined the role of miR-24 in gastric cancer (GC).

METHODS

The expression of miR-24 in GC tissues compared with matched non-tumor tissues and GC cells was detected by qRT-PCR. Synthetic short single or double stranded RNA oligonucleotides and lentiviral vectors were used to regulate miR-24 expression in GC cells to investigate its function in vitro and in vivo.

RESULTS

miR-24 was significantly downregulated in GC tissues compared with matched non-tumor tissues and was associated with tumor differentiation. Ectopic expression of miR-24 in SGC-7901 GC cells suppressed cell proliferation, migration and invasion in vitro as well as tumorigenicity in vivo by inducing cell cycle arrest in G0/G1 phase and promoting cell apoptosis. Furthermore, we identified RegIV as a target of miR-24 and demonstrated that miR-24 regulated RegIV expression via binding its 3' untranslated region.

CONCLUSIONS

miR-24 functions as a novel tumor suppressor in GC and the anti-oncogenic activity may involve its inhibition of the target gene RegIV. These findings suggest the possibility for miR-24 as a therapeutic target in GC.

MDM2 rs2279744 and TP53 rs1042522 polymorphisms associated with etoposide- and cisplatin-induced grade III/IV neutropenia in Chinese extensive-stage small-cell lung cancer patients

BACKGROUND/AIMS

Etoposide and cisplatin (EP) chemotherapy is the most frequently used regimen in extensive-stage small-cell lung cancer (SCLC) patients, although the side effects (e.g., neutropenia) are high. This study investigates the association of the MDM2 rs2279744 and TP53 rs1042522 single-nucleotide polymorphisms (SNPs) with EP-induced grade III/IV neutropenia and with response to EP in extensive-stage SCLC patients.

METHODS

Blood samples from 119 extensive-stage SCLC patients were subjected to genotyping of these 2 SNPs, using the allele-specific matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) mass spectrometry for determining the association with neutropenia in the patients.

RESULTS

The data showed that patients carrying the MDM2 rs2279744-GG genotype were associated with a lower incidence of grade III/IV neutropenia in the recessive and additive models, while the TP53 rs1042522-CC genotype was associated with a higher incidence in the recessive model. Furthermore, the combination of the MDM2 rs2279744-TT+TG and the TP53 rs1042522-CC genotype was associated with a significantly higher incidence of grade III/IV neutropenia. And the combination of the MDM2 rs2279744-GG and the TP53 rs1042522-GG+GC genotype was associated with the lowest incidence of grade III/IV neutropenia.

CONCLUSIONS

MDM2 rs2279744 and TP53 rs1042522 SNPs were associated with EP-induced high-grade neutropenia in extensive-stage SCLC patients. Further studies are needed to investigate the underlying mechanisms.

Investigation of genetic polymorphisms related to the outcome of radiotherapy for prostate cancer patients

The purpose of this study was to evaluate the association between ATM, TP53 and MDM2 polymorphisms in prostate cancer patients and morbidity after radiotherapy. The presence of ATM (rs1801516), TP53 (rs1042522, rs1800371, rs17878362, rs17883323, and rs35117667), and MDM2 (rs2279744) polymorphisms was assessed by direct sequencing of PCR fragments from 48 patients with histologically proven prostate adenocarcinoma and treated with external beam radiation. The side effects were classified according to the Radiation Therapy Oncology Group (RTOG) score. The results showed no association between clinical characteristics and the development of radiation toxicities (P > 0.05). The C>T transition in the position 16273 (intron 3) of TP53 (rs35117667) was significantly associated with the risk of acute skin toxicity (OR: 0.0072, 95% CI 0.0002–0.227, P = 0.003). The intronic TP53 polymorphism at position 16250 (rs17883323) was associated with chronic urinary toxicity (OR: 0.071, 95%CI 0.006–0.784, P = 0.032). No significant associations were found for the remaining polymorphisms (P > 0.05). The results show that clinical characteristics were not determinant on the developing of radiation sensitivity in prostate cancer patients, and intronic TP53 polymorphisms would be associated with increased acute and chronic radiation toxicities. These observations corroborate the importance of investigating the genetic profile to predict adverse side effects in patients undergoing radiotherapy.

Prognostic assessment of apoptotic gene polymorphisms in non-small cell lung cancer in Chinese

Apoptosis plays a key role in inhibiting tumor growth, progression and resistance to anti-tumor therapy. We hypothesized that genetic variants in apoptotic genes may affect the prognosis of lung cancer. To test this hypothesis, we selected 38 potentially functional single nucleotide polymorphisms (SNPs) from 12 genes (BAX, BCL2, BID, CASP3, CASP6, CASP7, CASP8, CASP9, CASP10, FAS, FASLG and MCL1) involved in apoptosis to assess their prognostic significance in lung cancer in a Chinese case cohort with 568 non-small cell lung cancer (NSCLC) patients. Thirty-five SNPs passing quality control underwent association analyses, 11 of which were shown to be significantly associated with NSCLC survival (P < 0.05). After Cox stepwise regression analyses, 3 SNPs were independently associated with the outcome of NSCLC (BID rs8190315: P = 0.003; CASP9 rs4645981: P = 0.007 and FAS rs1800682: P = 0.016). A favorable survival of NSCLC was significantly associated with the genotypes of BID rs8190315 AG/GG (adjusted HR = 0.65, 95% CI: 0.49-0.88), CASP9 rs4645981 AA (HR = 0.22, 95% CI: 0.07-0.69) and FAS rs1800682 GG (adjusted HR = 0.67, 95% CI: 0.46-0.97). Time-dependent receptor operation curve (ROC) analysis revealed that the area under curve (AUC) at year 5 was significantly increased from 0.762 to 0.819 after adding the risk score of these 3 SNPs to the clinical risk score. The remaining 32 SNPs were not significantly associated with NSCLC prognosis after adjustment for these 3 SNPs. These findings indicate that BID rs8190315, CASP9 rs4645981 and FAS rs1800682 polymorphisms in the apoptotic pathway may be involved in the prognosis of NSCLC in the Chinese population.

The association between TP53 Arg72Pro polymorphism and lung cancer susceptibility: evidence from 30,038 subjects

BACKGROUND

The TP53 codon 72 polymorphism has been associated with the individual susceptibility to lung cancer. However, the association remains uncertain and varies with ethnicity, smoking status, cancer histology, and stage.

METHODS

We performed a meta-analysis to evaluate the relationship between TP53 Arg72Pro polymorphism and lung cancer susceptibility basing on 15,647 lung cancer patients and 14,391 controls from 36 published literatures. We also performed stratified analysis in populations of different ethnicities, smoking statuses, lung cancer stages, and histological types.

RESULTS

The analysis showed a significantly increased lung cancer susceptibility among Pro allele carriers (P < 0.001, odds ratio (OR) = 1.14, 95% confidence interval (CI) = 1.1-1.19), especially for smokers (P < 0.001, OR = 1.29, 95% CI = 1.12-1.47). Stratified analysis indicated that Pro72 elevates lung cancer susceptibility in Asians, while it has no effect on lung cancer risk of Caucasians. Moreover, Pro carriers present an increased risk of developing squamous cell carcinoma and adenocarcinoma, instead of large cell carcinoma and small cell carcinoma. Interestingly, patients with the Pro allele seemed to be diagnosed with lung cancer at the early stages (stage I-II, P = 0.008, OR = 1.2, 95% CI = 1.05-1.37).

CONCLUSIONS

Our results suggest that the Pro allele acts as a risk factor for development of lung cancer, especially for smokers and Asians.

Polymorphism Arg72Pro of p53 confers susceptibility to squamous cell carcinoma of lungs in a North Indian population

The causes of lung cancer might be many, but genetic variation in the genes of carcinogen-metabolizing enzymes, tumor suppressor proteins, and/or DNA-repairing enzymes can also play a significant role in lung cancer susceptibility. The tumor suppressor protein p53 functions to induce cell cycle arrest, DNA repair, or apoptosis. Polymorphism in its gene can, therefore, play a significant role in cancer susceptibility. Present report evaluated the association of polymorphism in exon 4 Arg72Pro (G>C) of the p53 gene with lung cancer susceptibility using 175 cancer cases and 202 controls from the North Indian population. Binary logistic regression analysis revealed that the Pro72Pro genotype was significantly associated with increasing risk for lung cancer in younger age patients (≤55 years) (adjusted odds ratio [OR]=2.72, 95% confidence intervals [95% CI] 0.99-7.85, p<0.05). Histological stratification of lung cancer revealed that the Pro72Pro genotype was associated with higher risk for squamous cell carcinoma (OR=3.05, 95% CI 1.07-8.87, p<0.05). Genetic variation Arg72Pro of the p53 gene may contribute to higher risk of SCC of lung in the North Indian population.

Multiple variants of TERT and CLPTM1L constitute risk factors for lung adenocarcinoma

Recent studies have shown that 5p15.33 is one of the chromosomal regions that is most consistently altered in lung cancer; common variants that are located in this region have been genotyped in various populations. However, the genetic contribution of these variants to carcinogenesis is relatively unknown. A clinic-based case-control study in Shanghai was undertaken on 196 patients with lung cancer and 229 healthy individuals. TERT rs2736100 and CLPTM1L rs401681 and rs402710 were genotyped using the ABI TaqMan Allelic Discrimination assay. For rs2736100, the G variant and the GG genotype were more frequent, whereas the TT genotype was less frequent in patients with lung adenocarcinoma than in controls. The CT genotype at rs401681 was more common and the TT genotype was rare in patients, and the differences were significant between lung adenocarcinoma patients and controls. This was also true for rs402710. Moreover, the frequency of the GGCTCT haplotype was higher and the TTTTTT frequency was lower in patients, especially those with lung adenocarcinoma. Aberrant linkage disequilibrium among the three SNPs was found in patients with lung adenocarcinoma. We conclude that multiple variants at 5p15.33 contribute to susceptibility to lung adenocarcinoma.

Association between XRCC1 ARG399GLN and P53 ARG72PRO polymorphisms and the risk of gastric and colorectal cancer in Turkish population

Gastric cancer is one of the most common cancers of the gastrointestinal system, and its overall five-year survival rate is still 15 % to 20 %, as it can mostly be diagnosed at an advanced stage. On the other hand, although colorectal cancer has a rather good prognosis, mortality is one half that of the incidence.As carcinogenesis is believed to involve reactive radicals that cause DNA adduct formation, impaired repair activity, and weakened tumour suppression, it would help to understand the role of the polymorphisms of nucleotide excision repair enzyme XRCC1 and of tumour suppressor gene p53 in gastric and colorectal cancers. Our study included 94 gastric cancer patients, 96 colorectal cancer patients, and 108 cancer-free individuals as control with the aim to see if there was an association between XRCC1 Arg399Gln and p53 Arg72Pro polymorphisms and cancer susceptibility. DNA was extracted from peripheral blood cells and genotypes were determined using the polymerase chain reaction-restriction fragment length polymorphism. Polymorphism p53 Arg72Pro was not associated with either gastric or colorectal carcinoma, while XRCC1 Arg399Gln was not associated with the increased risk of colorectal cancer. However, XRCC1 homozygous Gln allele at codon 399 was associated with 2.54 times higher risk of gastric cancer.

Single-nucleotide polymorphisms (5p15.33, 15q25.1, 6p22.1, 6q27 and 7p15.3) and lung cancer survival in the European Prospective Investigation into Cancer and Nutrition (EPIC)

The single-nucleotide polymorphisms (SNPs) rs402710 (5p15.33), rs16969968 and rs8034191 (15q25.1) have been consistently identified by genome-wide association studies (GWAS) as significant predictors of lung cancer risk, while rs4324798 (6p22.1) was previously found to influence survival time in small-cell lung cancer (SCLC) patients. Using the same population of one of the original GWAS, we investigated whether the selected SNPs and 31 others (also identified in GWAS) influence survival time, assuming an additive model. The effect of each polymorphism on all cause survival was estimated in 1094 lung cancer patients, and lung cancer-specific survival in 763 patients, using Cox regression adjusted for a priori confounders and competing causes of death where appropriate. Overall, after 1558 person-years of post-diagnostic follow-up, 874 deaths occurred from all causes, including 690 from lung cancer. In the lung cancer-specific survival analysis (1102 person-years), only rs7452888 (6q27) and rs2710994 (7p15.3) modified survival, with adjusted hazard ratios of 1.19 (P = 0.009) and 1.32 (P = 0.011) respectively, taking competing risks into account. Some weak associations were identified in subgroup analysis for rs16969968 and rs8034191 (15q25.1) and rs4324798 (6p22.1) and survival in never-smokers, as well as for rs402710 in current smokers and SCLC patients. In conclusion, rs402710 (5p15.33), rs16969968 and rs8034191 (both 15q25.1) and rs4324798 (6p22.1) were found to be unrelated to survival times in this large cohort of lung cancer patients, regardless of whether the cause of death was from lung cancer or not. However, rs7452888 (6q27) was identified as a possible candidate SNP to influence lung cancer survival, while stratified analysis hinted at a possible role for rs8034191, rs16969968 (15q25.1) and rs4324798 (6p22.1) in influencing survival time in lung cancer patients who were never-smokers, based on a small sample.

Pharmacogenetic and germline prognostic markers of lung cancer

INTRODUCTION

Lung cancer is the leading global cause of cancer-related mortality. Interindividual variability in treatment response and cancer outcomes has focused attention on genetic polymorphisms as prognostic markers. We evaluated the overall contribution of candidate polymorphism association studies to our current understanding of the genetic predictors of lung cancer outcomes.

METHODS

We examined the results of 90 studies that evaluated associations between genetic polymorphisms and lung cancer outcomes published between January 1990 and May 2009.

RESULTS

A total of 170 genetic variations in 90 studies were identified. Overall survival was a primary outcome in 81% of the studies and toxicity in 19%. Candidate polymorphisms in the DNA repair/synthesis pathway were the most frequently studied. Strong evidence in large-scale confirmatory studies of any single polymorphism was lacking. Polymorphisms of EGFR, XRCC1, and ERCC1 were associated with pharmacogenetic outcomes, whereas polymorphisms of MDM2, p53, and GSTM1 were associated with prognostic outcomes. All remaining polymorphisms had results lacking or failing replication testing. Heterogeneity in study populations, incomplete reporting of important population or study characteristics, inadequate power, and inconsistencies in methodology were common.

CONCLUSIONS

Although the quality of existing studies involving the candidate polymorphism approach is highly variable, a small set of candidate polymorphisms was identified as potential biomarkers of clinical or pharmacogenetic outcome and would benefit from further replication testing. Newer approaches including haplotype tagging, pathway, genome-wide association, and combination methods with validative approaches may facilitate a more accurate prediction of lung cancer outcomes by genetic variation.

p53 codon 72 polymorphism and the risk of lung cancer in a Korean population

The aim of this study was to assess whether p53 codon 72 polymorphism is associated with an increased risk of lung cancer (LC) in a South Korean population. We conducted a population-based, large-scale, case-control study including 3939 patients with LC and 1700 controls. P53 codon 72 polymorphism was determined by real-time polymerase chain reaction (PCR). The frequencies of p53 codon 72 polymorphisms (Arg/Arg, Arg/Pro, and Pro/Pro) in LC were 37.0%, 46.2%, and 16.7%, respectively; frequencies in the controls were 43.2%, 45.6%, and 11.2%, respectively (p<0.01). The Arg/Pro and Pro/Pro genotype were significantly associated with increased risk of LC (odds ratio (OR)=1.22, 95% confidence interval (CI)=1.06-1.14 and OR=1.83, 95% CI=1.48-2.26, respectively) compared with the Arg/Arg genotype. Risk was compared in different subgroups. The OR of Pro/Pro genotype was significantly higher in small cell lung cancer (SCC) and squamous cell carcinoma (SQC) than in adenocarcinoma (ADC). Higher OR of Pro/Pro genotype was also seen among males. However, relationships between gender, age, smoking, and genotypes were not found. P53 codon 72 polymorphism was associated with an increased risk of LC in this Korean population; the association was especially noteworthy in SQC, SCC, and males.

Tobacco, Genetic Susceptibility and Lung cancer

Exposure to tobacco smoke is an established risk factor for lung cancer, although a possible role for genetic susceptibility in the development of lung cancer has been inferred from familial clustering of the disease and segregation analysis. Findings of familial aggregation and statistical evidence for a major susceptibility gene have led to the search for high penetrant, rare, single genes and low penetrant, high frequency susceptibility genes for lung cancer. The relatively small number of linkage studies conducted to date, have identified potential lung cancer susceptibility loci on chromosomes 6q, 12p, and 19q. A variety of studies have examined single nucleotide polymorphisms of several low penetrant, high frequency genes encoding for enzymes involved in the metabolism of carcinogens and DNA damage repair, as likely candidate susceptibility genes. These studies have produced somewhat conflicting findings and, when significant, only modest associations have been reported. Relatively few studies have looked for potential gene-environment interactions, explored associations between two or more genetic polymorphisms or evaluated interactions between genetic polymorphisms and endogenous risk factors. Few large scale genome wide association studies conducted recently have provided evidence that common variation on chromosome 15q25.1, 5p15.33 and 6p21.33 influences lung cancer risk and cancer types with strong environmental risk factors. It is hoped that newer research strategies, selecting candidate genes within pathways and genotype at multiple markers within a gene, employing new technologies, may allow complete coverage of the variation within candidate genes in multiple pathways and to unravel the genetic susceptibility to lung cancer. This knowledge could, in turn, be used to identify persons at risk, to individualize treatments such as chemoprevention, to personalize harms of smoking and to motivate cessation.

TP53 Arg72Pro polymorphism and lung cancer risk: a meta-analysis

No clear consensus has been reached on the TP53 Arg72Pro polymorphism (G12139C) and lung cancer risk. Thus, a meta-analysis was conducted to summarize the possible association. There was no statistical association between 12139C (Pro allele) and lung cancer risk in Caucasians compared with 12139G allele. However, the association was observed in all subjects (9,387 patients and 9,922 controls, p=0.04, OR=1.08, 95% CI 1.00-1.17), as well as in Asians (p=0.0004, OR=1.14, 95% CI 1.06-1.22). The association was also found in Asians under recessive genetic model (p<0.00001, OR=1.37, 95% CI 1.20-1.57) and homozygote comparison (CC vs. GG) (p<0.0001, OR=1.34, 95% CI 1.16-1.56). 12139C allele might increase the lung adenocarcinoma risk compared with 12139G allele (p=0.01, OR=1.11, 95% CI 1.02-1.21), and the effect was also found under recessive genetic model (p=0.003, OR=1.28, 95% CI 1.09-1.50) and homozygote comparison (CC vs. GG) (p=0.007, OR=1.28, 95% CI 1.07-1.52). There was an elevated association between the 12139C and the stage I lung cancer under dominant genetic model (p=0.04, OR=1.48, 95% CI 1.02-2.16), but no association was observed in other stages. No association of smoking was found between 12139C allele and lung cancer under recessive genetic model. Our result indicated that 12139C might increase the risk of lung cancer under recessive genetic model in adenocarcinoma, in Asians, and in lung cancer stage I. More studies stratified for lung cancer stage-genotyping interaction should be performed to clarify the role of TP53 Arg72Pro polymorphism in the development of lung cancer.

P53 polymorphism and lung cancer susceptibility: a pooled analysis of 32 case-control studies

To explore the real association between p53 codon 72 polymorphism and lung cancer risk, a pooled analysis of 32 case-control studies involving 19,255 subjects was conducted. When all 32 studies were pooled into the analysis, significantly elevated lung cancer risks were associated with variant genotypes in all genetic models (for Pro/Arg vs. Arg/Arg: OR 1.21, 95% CI 1.01-1.23; for Pro/Pro vs. Arg/Arg: OR 1.20, 95% CI 1.03-1.39; for Pro/Pro + Pro/Arg vs. Arg/Arg: OR 1.14, 95% CI 1.03-1.25; for Pro/Pro vs. Arg/Arg + Pro/Arg: OR 1.06, 95% CI 1.01-1.12). In the subgroup analysis by ethnicity, histological type, or smoking status, significantly increased risks were found in subgroups such as Asians, Caucasians, lung adenocarcinoma patients, or smokers, respectively. In conclusion, our results suggest that the Pro allele at p53 codon 72 is emerging as a low-penetrance susceptibility allele for lung cancer development.

A meta-analysis of TP53 codon 72 polymorphism and lung cancer risk: evidence from 15,857 subjects

The genetic polymorphism of TP53 codon 72 is thought to have significant effect on lung cancer risk, but the results are inconsistent. In this meta-analysis, we assessed 23 published studies involving 15,857 subjects of the association between TP53 codon 72 polymorphism and risk of lung cancer. For the homozygote Pro/Pro and Pro allele carriers (Pro/Pro+Pro/Arg), the ORs for all studies combined (7495 cases and 8362 controls) were 1.221 (95% CI=1.046-1.425; P=0.021 for heterogeneity) and 1.148 (95% CI=1.040-1.266; P=0.008 for heterogeneity). In the stratified analysis by ethnicity, significantly increased risks were found in Asians (3254 cases and 3350 controls) for both the homozygote Pro/Pro (OR=1.395; 95% CI=1.206-1.613; P=0.806 for heterogeneity) and the Pro allele carriers (OR=1.109; 95% CI=1.000-1.228; P=0.458 for heterogeneity). In Caucasians (3359 cases and 3953 controls), significantly elevated risk was associated with Pro allele carriers (OR=1.180; 95% CI=1.029-1.353; P=0.073 for heterogeneity). In the subgroup analyses by pathological type, the ORs for the homozygote Pro/Pro and Pro allele carriers were 1.289 (95% CI=1.027-1.618; P=0.096 for heterogeneity) and 1.168 (95% CI=1.062-1.284; P=0.231 for heterogeneity) for lung adenocarcinoma (2724 cases and 6591 controls). When stratified by smoking status, the pooled OR was 1.440 (95% CI=1.078-1.923; P=0.042 for heterogeneity) for the Pro allele carriers among smokers (1480 cases and 1414 controls). Although some statistical bias could not be eliminated, this meta-analysis suggests that the Pro allele is a low-penetrant risk factor for developing lung cancer. Additionally, we found that this phenomenon was more prominent in subgroups such as in Asians and Caucasians, in lung adenocarcinoma, or in smokers.

Contribution of polymorphism in codon 72 of TP53 gene to laryngeal cancer in Polish patients

The amino acid substitution Arg72Pro in the TP53 protein has an impact on the biochemical and biological activity of this protein, and is associated with several types of cancers. However, the Arg72Pro polymorphism exhibits inconsistent contribution as a risk factor in various cancer types. Therefore, using PCR-RFLPs, we investigated the distribution of Arg72Pro genotypes and alleles in patients with laryngeal cancer (n=123) and controls (n=300) in Poland. We observed that patients with the Pro/Pro and Arg/Pro TP53 genotypes displayed a 1.755-fold increased risk of laryngeal cancer (95% CI=1.149-2.680, P=0.0099). However, we did not find a significant increase in laryngeal cancer risk for the homozygous Pro/Pro TP53 genotype OR=2.093 (95% CI=1.046-4.192, P=0.0530). This result suggests that the TP53Pro variant may contribute to the risk of laryngeal cancer development in Polish patients.