Prognostic role of p53 codon 72 polymorphism in gastric cancer patients treated with fluorouracil-based adjuvant chemotherapy

Pharmacogenetic Variation and Its Clinical Relevance in a Latin American Rural Population

Latin-American populations have been largely underrepresented in genomic studies of drug response and disease susceptibility. In this paper, we present a genome-wide Chilean dataset from Talca based on the Illumina Global Screening Array. This let us to compare the frequency of gene variants involved in response to drugs among our population and others, taking data from the 1000 Genomes Project. We found four single-nucleotide polymorphisms with low prevalence in Chileans when compared with African, Amerindian, East and South Asian, and European populations: rs2819742 (RYR2), rs2631367 (SLC22A5), rs1063320 (HLA-G), and rs1042522 (TP53). Moreover, two markers showed significant differences between lower and higher proportion of Mapuche ancestry groups: rs1719247 (located in an intergenic region in chromosome 15; p-value = 6.17 × 10⁻⁵, Bonferroni corrected p-value = 0.02) and rs738409 (A nonsynonymous gene variant in the PNPLA3 gene; p-value = 9.02 × 10⁻⁵, Bonferroni corrected p-value = 0.04). All of these polymorphisms have been shown to be associated with diverse pathologies, such as asthma, cancer, or chronic hepatitis B, or to be involved in a different response to drugs, such as metformin, HMG-CoA reductase inhibitors, or simvastatin. The present work provides a pharmacogenetic landscape of an understudied Latin American rural population and supports the notion that pharmacogenetic studies in admixed populations should consider ancestry for a higher accuracy of the results. Our study stresses the relevance of the pharmacogenomic research to provide guidance for a better choice of the best treatment for each individual in a population with admixed ancestry.

Analysis of 13 TP53 and WRAP53 polymorphism frequencies in russian populations

In the last decade the search for and annotation of human genome polymorphisms associated with phenotype have become particularly important concerning the opportunity of their use in medical and population genetics, pharmacogenomics and evolutionary biology. The study was aimed to calculate the frequencies and analyze the prevalence of 13 germline polymorphisms of two genes, ТР53 encoding the genome-keeper p53 protein and WRAP53 involved in regulation of p53 production, in 28 Russian populations. We obtained data on 9 exonic ТР53 variants (rs587781663, rs17882252, rs150293825, rs112431538, rs149633775, rs144340710, rs1042522, rs1800371, rs201753350), one intronic polymorphism (rs17881850), and three variants of WRAP53 (rs17880282, rs2287499, rs34067256). In the majority of populations the sample size was over 50 people (except five populations with 30–49 surveyed people). The alternative alleles’ population frequencies for studies genetic variants in most Russian populations were close to appropriate allele frequencies in European and Asian populations of similar origin taken from global databases. The exceptions were six populations ("Central Caucasus", "Dagestan", "northern Russians", "southeastern Russians", "Tatars" and "Transcaucasia") with increased alternative alleles’ population frequencies. All listed populations except the population of “southeastern Russians” are characterized by polymorphisms with high allele frequencies not satisfying the Hardy–Weinberg principle.

A Shared Susceptibility Locus in the p53 Gene for both Gastric and Esophageal Cancers in a Northwestern Chinese Population

Background: Upper gastrointestinal tract cancers are the leading causes of cancer-related deaths in Northwest China and they share many similarities in terms of histological type, risk factors, and genetic variants. We hypothesized that shared common single-nucleotide polymorphisms (SNPs) in the p53 pathway exist between patients with gastric and esophageal cancer (EC) patients. Materials and Methods: A case-control study to examine genetic variants in the p53 pathway was conducted with subjects from a high-incidence area for upper gastrointestinal cancers of China. Multiple logistic regression analyses were used to estimate the association of genotypes with gastric cancer and EC risks. Median survival was estimated by using the Kaplan-Meier method and compared by using the log-rank test. Results: Compared with the rs1042522 Pro allele, the rs1042522 Arg allele was associated with an increased risk of gastric cancer (1.810×) and an increased risk of EC (2.285×). The rs1042522 Arg allele carriers who also smoked or consumed alcohol had a further increased risk for gastric cancer odds ratios (OR_smoking = 2.422, OR_drinking = 5.152) and EC (OR_smoking = 5.310, OR_drinking = 8.359). No association was found between the rs1042522 genotypes and survival (p > 0.05). Conclusion: The p53 rs1042522 arg allele together with tobacco smoking and alcohol drinking, was associated with an increased risk, for gastric cancer and EC, but not the survival among northwestern Chinese patients. These associations warrant confirmatory studies.

Molecular Bases of Mechanisms Accounting for Drug Resistance in Gastric Adenocarcinoma

Gastric adenocarcinoma (GAC) is the most common histological type of gastric cancer, the fifth according to the frequency and the third among the deadliest cancers. GAC high mortality is due to a combination of factors, such as silent evolution, late clinical presentation, underlying genetic heterogeneity, and effective mechanisms of chemoresistance (MOCs) that make the available antitumor drugs scarcely useful. MOCs include reduced drug uptake (MOC-1a), enhanced drug efflux (MOC-1b), low proportion of active agents in tumor cells due to impaired pro-drug activation or active drug inactivation (MOC-2), changes in molecular targets sensitive to anticancer drugs (MOC-3), enhanced ability of cancer cells to repair drug-induced DNA damage (MOC-4), decreased function of pro-apoptotic factors versus up-regulation of anti-apoptotic genes (MOC-5), changes in tumor cell microenvironment altering the response to anticancer agents (MOC-6), and phenotypic transformations, including epithelial-mesenchymal transition (EMT) and the appearance of stemness characteristics (MOC-7). This review summarizes updated information regarding the molecular bases accounting for these mechanisms and their impact on the lack of clinical response to the pharmacological treatment currently used in GAC. This knowledge is required to identify novel biomarkers to predict treatment failure and druggable targets, and to develop sensitizing strategies to overcome drug refractoriness in GAC.

Establishment and characterization of 18 human colorectal cancer cell lines

Colorectal cancer (CRC) represents the third most frequently diagnosed malignancy worldwide and is the second most common cause of tumor-associated mortalities in Korea. Due to the disease’s aggressive behavior, the 5-year survival rate for CRC patients remains unpromising. Well-characterized cell lines have been used as a biological model for studying the biology of cancer and developing novel therapeutics. To assist in vitro studies, 18 CRC cell lines (SNU-1566, SNU-1983, SNU-2172, SNU-2297, SNU-2303, SNU-2353B, SNU-2359, SNU-2373B, SNU-2407, SNU-2423, SNU-2431, SNU-2465, SNU-2493, SNU-2536C, SNU-2621B, SNU-NCC-61, SNU-NCC-376, and SNU-NCC-377) derived from Korean patients were established and characterized in the present study. General characteristics of each cell line including doubling time, in vitro morphology, mutational profiles, and protein expressions of CRC-related genes were described. Whole exome sequencing was performed on each cell line to configure mutational profiles. Single nucleotide variation, frame shift, in-frame deletions and insertions, start codon deletion, and splice stop codon mutation of various genes were found and classified based on their pathogenicity reports. In addition, cell viability was assayed to measure their sensitivities to 24 anti-cancer drugs including anti-metabolites, kinase inhibitors, histone deacetylase inhibitors, alkylating inhibitors, and topoisomerase inhibitors, all widely used for various cancers. On testing, five CRC cell lines showed MSI, of which MLH1 or MSH6 gene was mutated. These newly established CRC cell lines can be used to investigate biological characteristics of CRC, particularly for investigating gene alterations associated with CRC.

Pharmacogenomics in Pediatric Oncology: Review of Gene-Drug Associations for Clinical Use

During the 3rd congress of the European Society of Pharmacogenomics and Personalised Therapy (ESPT) in Budapest in 2015, a preliminary meeting was held aimed at establishing a pediatric individualized treatment in oncology and hematology committees. The main purpose was to facilitate the transfer and harmonization of pharmacogenetic testing from research into clinics, to bring together basic and translational research and to educate health professionals throughout Europe. The objective of this review was to provide the attendees of the meeting as well as the larger scientific community an insight into the compiled evidence regarding current pharmacogenomics knowledge in pediatric oncology. This preliminary evaluation will help steer the committee’s work and should give the reader an idea at which stage researchers and clinicians are, in terms of personalizing medicine for children with cancer. From the evidence presented here, future recommendations to achieve this goal will also be suggested.

Perspectives on new biomarkers in gastric cancer: Diagnostic and prognostic applications

Gastric cancer is considered one of the most deadly tumors worldwide. Even with the decline in its incidence, the mortality rate of this disease has remained high, mainly due to its late diagnosis and to the lack of precise prognostic markers. The main purpose of this review is to present genetic, epigenetic and proteomic molecular markers that may be used in a diagnostic and prognostic manner and to discuss the pros and cons of each type of marker for improving clinical practice. In this sense, we observed that the use of genetic markers, especially mutations and polymorphisms, should be carefully considered, as they are strongly affected by ethnicity. Proteomic-based markers show promise, but the higher costs of the associated techniques continue to make this approach expensive for routine use. Alternatively, epigenetic markers appear to be very promising, as they can be detected in bodily fluids as well as tissues. However, such markers must be used carefully because epigenetic changes may occur due to environmental factors and aging. Despite the advances in technology and its access, to date, there are few defined biomarkers of prognostic and diagnostic use for gastric tumors. Therefore, the use of a panel of several approaches (genetic, epigenetic and proteomic) should be considered the best alternative for clinical practice.

A compensatory role of NF-κB to p53 in response to 5-FU-based chemotherapy for gastric cancer cell lines

Despite of remarkable improvement of postoperative 5-FU–based adjuvant chemotherapy, the relapse rate of gastric cancer patients who undergo curative resection followed by the adjuvant chemotherapy remains substantial. Therefore, it is important to identify prediction markers for the chemotherapeutic efficacy of 5-FU. We recently identified NF-κB as a candidate relapse prediction biomarker in gastric cancer. To evaluate the biological significance of NF-κB in the context of 5-FU–based chemotherapy, we analyzed the NF-κB-dependent biological response upon 5-FU treatment in gastric cancer cell lines. Seven genes induced by 5-FU treatment in an NF-κB-dependent manner were identified, five of which are known p53 targets. Knockdown of RELA, which encodes the p65 subunit of NF-κB, decreased both p53 and p53 target protein levels. In contrast, NF-κB was not affected by TP53 knockdown. We also demonstrated that cell lines bearing Pro/Pro homozygosity in codon72 of p53 exon4, which is important for NF-κB binding to p53, are more resistant to 5-FU than those with Arg/Arg homozygosity. We conclude that NF-κB plays an important role in the response to 5-FU treatment in gastric cancer cell lines, with a possible compensatory function of p53. These results suggest that NF-κB is a potential 5-FU-chemosensitivity prediction marker that may reflect 5-FU-induced stress-response pathways, including p53.

Effect of TP53 codon 72 and MDM2 SNP309 polymorphisms on survival of gastric cancer among patients who receiving 5-fluorouracil-based postoperative adjuvant chemotherapy

PURPOSE

Several studies have examined the prognostic value of the TP53 Arg72Pro polymorphism (rs1042522) and/or MDM2 SNP309 (rs2279744) in multiple tumors. Our aim was to determine whether these two genetic variants were correlated with clinical outcome of gastric cancer.

METHODS

We genotyped the two SNPs, TP53 codon 72 polymorphism and MDM2 SNP309, in 940 gastric cancer patients with complete follow-up information and analyzed the correlation between the SNPs and gastric cancer survival.

RESULTS

The two SNPs were not significantly associated with gastric cancer survival. However, the TP53 codon 72 polymorphism had a prominent correlation with clinical outcome of patients receiving 5-fluorouracil (5-Fu)-based postoperative chemotherapy [Arg/Arg + Arg/Pro vs. Pro/Pro, adjusted hazard ratio (HR) = 1.63, 95 % confidence interval (CI) = 1.08-2.44]. Moreover, the unfavorable effect of Arg allele on survival outcome was more predominant for subgroups of older (age >60 years), male, intestinal histology type, advanced stage (T3/T4), and none metastasis of lymph node (N0) or distant (M0) (adjusted HR = 2.34, 95 % CI = 1.24-4.44 for age >60 years; 1.72, 1.10-2.69 for male; 2.30, 1.10-4.80 for intestinal; 1.62, 1.01-2.59 for T3/T4; 3.42, 1.26-9.24 for N0; and 1.62, 1.06-2.47 for M0). Among multiple chemotherapy regimens, the association was only significant in the subgroup of 5-Fu/calcium folinate plus oxaliplatin (FOLFOX) chemotherapy regimen (adjusted HR = 4.47, 95 % CI = 1.21-16.55).

CONCLUSIONS

Our findings showed that TP53 codon 72 polymorphism was associated with survival of gastric cancer patients treated with 5-Fu-based postoperative chemotherapy. The codon 72 polymorphism may be a potential prognostic factor.

HIF-1alpha is an unfavorable determinant of relapse in gastric cancer patients who underwent curative surgery followed by adjuvant 5-FU chemotherapy

Among several chemotherapeutic agents, 5-fluorouracil (5-FU) has been widely used as a key drug in adjuvant chemotherapy for gastric cancer. However, no reliable marker, which predicts the response to 5-FU in an adjuvant setting, has been identified. Hypoxia-induced drug resistance, via upregulation of HIF-1alpha, is a major obstacle in the development of effective cancer therapy. However, few clinical studies have so far assessed the relationship between the HIF-1alpha expression and the chemo-resistance of gastric cancer patients in an adjuvant setting. We established 2 HIF-1alpha knockdown gastric cancer cell lines in order to clarify the role of HIF-1alpha in chemo-resistance against 5-FU. Furthermore, expression of HIF-1alpha was immunohistochemically assessed in 91 resected specimens. Sixty-four of 91 patients received 5-FU adjuvant chemotherapy after surgery. HIF-1alpha expression was associated with the significantly shorter relapse-free survival and disease-specific survival in the 64 patients of adjuvant group (p = 0.026, 0.014, respectively), but not in the 27 of surgery group. Multivariate analysis showed that HIF-1alpha was an independent risk factor for relapse in 64 patients in the adjuvant group (p = 0.029). In conclusion, the current study confirmed, for the first time that HIF-1alpha expression is an independent risk factor for relapse in high-risk gastric cancer patients who underwent curative surgery followed by adjuvant 5-FU chemotherapy. A favorable effect of 5-FU might therefore be expected in patients that do not express HIF-1alpha, whereas, other types of chemotherapy or additional treatments, such as HIF-1alpha inhibitors, should be considered in patients that do express HIF-1alpha.

Toward molecularly selected chemotherapy for advanced gastric cancer: state of the art and future perspectives

In the last few years therapeutic options for gastric cancer patients have slowly, but constantly expanded following the introduction of both new chemotherapy agents and innovative indications for treatment. Along with the medical therapy also our knowledge of the molecular mechanisms underlying this disease has progressively improved. However although the available treatment options have undoubtedly increased no clear definitive indications can be made for a standard chemotherapy regimen and we are still unable to accurately select the appropriate treatment for the appropriate patient. Many molecular determinants of response/toxicity to chemotherapy agents have been identified, but only few of them seem to possess the necessary potential for a subsequent application in the clinical practice. Some of these factors have also been indicated as a therapeutic target for a novel class of anti-cancer compounds. This systematic review will analyse available data about these factors with the aim to constitute a starting point for future research.

ERCC1 polymorphism, expression and clinical outcome of oxaliplatin-based adjuvant chemotherapy in gastric cancer

AIM: To determine the influence of excision repair cross complementing group 1 (ERCC1) codon 118 polymorphism and mRNA level on the clinical outcome of gastric cancer patients treated with oxaliplatin-based adjuvant chemotherapy.

METHODS: Eighty-nine gastric cancer patients treated with oxalipatin-based adjuvant chemotherapy were included in this study. ERCC1 codon 118 C/T polymorphism was tested by polymerase chain reaction-ligation detection reaction (PCR-LDR) method in peripheral blood lymphocytes of those patients; and the intratumoral ERCC1 mRNA expression was measured using reverse transcription PCR in 62 patients whose tumor tissue specimens were available.

RESULTS: No significant relationship was found between ERCC1 codon 118 polymorphism and ERCC1 mRNA level. The median relapse-free and overall survival period was 20.1 mo and 28.4 mo, respectively. The relapse-free and overall survivals in patients with low levels of ERCC1 mRNA were significantly longer than those in patients with high levels (P < 0.05), while there was no significant association found between ERCC1 118 genotypes and the disease prognosis. Multivariate analysis also showed that ERCC1 mRNA level was a potential predictor for relapse and survival in gastric cancer patients treated with oxaliplatin-based adjuvant chemotherapy (P < 0.05).

CONCLUSION: ERCC1 codon 118 polymorphism has no significant impact on ERCC1 mRNA expression, and the intratumoral ERCC1 mRNA level but not codon 118 polymorphism may be a useful predictive parameter for the relapse and survival of gastric cancer patients receiving oxaliplatin-based adjuvant chemotherapy.

The polymorphisms of TS and MTHFR predict survival of gastric cancer patients treated with fluorouracil-based adjuvant chemotherapy in Chinese population

PURPOSE

The aim of this study was to investigate the association of the thymidylate synthase (TS) and methylenetetrahydrofolate reductase (MTHFR) polymorphisms with the clinical outcomes of gastric cancer patients treated with 5-FU-based adjuvant chemotherapy.

METHODS

One-hundred and sixteen patients with gastric cancer were treated with 5-FU-based adjuvant chemotherapy. The TS (a 28-bp tandem repeat polymorphism in the TS enhancer region (TSER) and a 6 bp deletion/insertion polymorphism in the 3'-untranslated region) and MTHFR C677T polymorphisms were determined in blood samples from those patients using PCR and PCR-LDR (ligation detection reaction) method, respectively.

RESULTS

The overall survival (OS) in patients with the TS ins6/ins6 genotype was significantly shorter than those in patients with the del6/del6 (P = 0.017) and ins6/del6 (P = 0.022) genotype. The relapse-free survival (RFS) and OS in patients with the MTHFR C/C genotype were significantly worse than those in patients with the T/T or C/T genotype (P = 0.043 and 0.040, respectively). Cox multivariate analysis also showed that patients with the TS ins6/ins6 genotype have worse OS than patients with the T/T or C/T genotype (HR = 2.437, P = 0.041), and the MTHFR C/C genotype was associated with shorter RFS (HR = 1.723, P = 0.031) and OS (HR = 1.681, P = 0.056). No significant association was found between the TSER polymorphism and the clinical outcomes (P > 0.05).

CONCLUSION

The polymorphisms of TS 3'-UTR ins6/del6 and MTHFR C677T appear to be potential prognostic factors in gastric cancer patients treated with 5-FU-based adjuvant chemotherapy, which may allow identification of gastric cancer patients who will benefit from 5-FU chemotherapy.