Significance of an exon 2 G4C14-to-A4T14 polymorphism in the p73 gene on survival in rectal cancer patients with or without preoperative radiotherapy

Germline and Somatic Pharmacogenomics to Refine Rectal Cancer Patients Selection for Neo-Adjuvant Chemoradiotherapy

Neoadjuvant chemoradiotherapy (nCRT) followed by radical surgery is the standard of care for patients with Locally Advanced Rectal Cancer (LARC). Current selection for nCRT is based on clinical criteria regardless of any molecular marker. Pharmacogenomics may be a useful strategy to personalize and optimize nCRT in LARC. This review aims to summarize the most recent and relevant findings about the role of germline and somatic pharmacogenomics in the prediction of nCRT outcome in patients with LARC, discussing the state of the art of their application in the clinical practice. A systematic literature search of the PubMed database was completed to identify relevant English-language papers published up to January 2020. The chemotherapeutic backbone of nCRT is represented by fluoropyrimidines, mainly metabolized by DPD (Dihydro-Pyrimidine Dehydrogenase, DPYD). The clinical impact of testing DPYD*2A, DPYD*13, c.2846A > T and c.1236G > A-HapB3 before a fluoropyrimidines administration to increase treatment safety is widely acknowledged. Other relevant target genes are TYMS (Thymidylate Synthase) and MTHFR (Methylene-Tetrahydro-Folate Reductase), whose polymorphisms were mainly studied as potential markers of treatment efficacy in LARC. A pivotal role of a TYMS polymorphism in the gene promoter region (rs34743033) was reported and was pioneeringly used to guide nCRT treatment in a phase II study. The pharmacogenomic analysis of other pathways mostly involved in the cellular response to radiation damage, as the DNA repair and the activation of the inflammatory cascade, provided less consistent results. A high rate of somatic mutation in genes belonging to PI3K (Phosphatidyl-Inositol 3-Kinase) and MAPK (Mitogen-Activated Protein Kinase) pathways, as BRAF (V-raf murine sarcoma viral oncogene homolog B1), KRAS (Kirsten Rat Sarcoma viral oncogene homolog), NRAS (Neuroblastoma RAS viral (v-ras) oncogene homolog), PIK3CA (Phosphatidyl-Inositol-4,5-bisphosphate 3-Kinase, Catalytic Subunit Alpha), as well as TP53 (Tumor Protein 53) was reported in LARC. Their pharmacogenomic role, already defined in colorectal cancer, is under investigation in LARC with promising results concerning specific somatic mutations in KRAS and TP53, as predictors of tumor response and prognosis. The availability of circulating tumor DNA in plasma may also represent an opportunity to monitor somatic mutations in course of therapy.

p73 G4C14-to-A4T14 polymorphisms are positively correlated with triple-negative breast cancer in southwestern China

p73 gene shares structural and functional similarities to p53 and plays an important role in modulating cell cycle arrest and apoptosis. A common non-coding polymorphism of p73 G4C14-to-A4T14 (rs2273953 and rs1801173) at exon 2 may affect gene expression, thus, it may lead to functional significance. The correlation of this polymorphism with clinicopathologic variables of patients with breast cancer has not been investigated. In this study, single-nucleotide polymorphisms (SNPs) of p73 G4C14-to-A4T14 were genotyped by Sequenom MassArray-iPLEX GOLD System in 170 patients with breast cancer. Data were analyzed via t test, chi-square test, and logistic regression analysis. There was no significant correlation between p73 G4C14-to-A4T14 polymorphisms and the patient characteristics, such as clinical TNM stage, menopausal status, axillary lymph node metastasis, pathological type, estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2). No significant relationship was observed between the p73 G4C14-to-A4T14 polymorphism and p73 protein expression in cancer tissues. The frequency of GC/GC genotype in patients with triple-negative breast cancer (TNBC) was 78.9 %, that of patients with others was 57.6 %, and the difference had statistical significance (χ ( 2 ) = 5.74, P = 0.02). p73 G4C14-to-A4T14 polymorphisms were negatively correlated with chemosensitivity for anthracycline-based chemotherapy in breast cancer (P > 0.05). p73 G4C14-to-A4T14 polymorphisms are positively correlated with TNBC, and p73 gene may play a critical role in a novel therapeutic strategy to TNBC. Additional larger studies are required to test these hypotheses.

Association between survivin -31G > C promoter polymorphism and cancer risk: a meta-analysis

Survivin is an inhibitor of apoptosis protein and has a crucial role in the development of cancer. The survivin -31G>C (rs9904341) promoter polymorphism influences survivin expression and has been implicated in cancer risk. However, conflicting results have been published from studies on the association between survivin -31G>C polymorphism and the risk of cancer. To clarify the role of this polymorphism in cancer, we performed a meta-analysis of all available and relevant published studies, involving a total of 3485 cancer patients and 3964 control subjects. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the strength of the associations. The overall results indicated that the variant genotypes were associated with a significantly increased cancer risk (CC vs GG: OR=1.58, 95% CI=1.20-2.10; CC/GC vs GG: OR=1.23, 95% CI=1.00-1.51; CC vs GG/GC: OR=1.51, 95% CI=1.23-1.85). In the stratified analyses, significantly increased risk was associated with the Asian populations (CC vs GG: OR=1.67, 95% CI=1.16-2.40; CC vs GG/GC: OR=1.50, 95% CI=1.17-1.91). We also performed the analyses by cancer type, and no statistical association was observed. The results suggest that the survivin -31G>C promoter polymorphism might be associated with an increased risk of cancer, especially in the Asian populations.

Relationship between p73 polymorphism and the immunohistochemical profile of the full-length (TAp73) and NH2-truncated (ΔNp73) isoforms in Tunisian patients

BACKGROUND

We examined the association of one linked GC/AT polymorphism at p73 with the risk of colorectal cancer.

AIM

In this study, we investigated whether this polymorphism was related to the risk of colorectal cancer, and whether there were relationships between the polymorphism and loss of heterozygosity, protein expression, or clinicopathologic variables.

MATERIALS AND METHODS

The p73 genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism in 150 Tunisian patients with colorectal cancer and in 204 healthy control subjects. Immunohistochemistry was performed on normal mucosa, primary tumor, and metastasis.

RESULTS

The frequencies of the genotypes were 52% for wild-type (GC/GC), 31% for heterozygotes (GC/AT), and 17% for variants(AT/AT) in patients, and 54%, 35%, and 11% in controls, respectively. There were no significant differences of the frequencies of the 3 genotypes between the patients and controls (P=0.11). We did not find any relationship of the genotypes with clinicopathologic features of patients. We found that patients with the GC/GC genotype had a significantly more favorable clinical outcome than the patients with the AT variants (AT/AT or GC/AT genotype). There were no significant difference between tumoral immunostaining and p73 polymorphism (P=0.16) but we found that the samples carrying the AT allele showed a tendency to be more stained in tumor. No loss of heterozygosity was observed at p73 locus. Our results suggest that the AT/AT genotype is significantly associated with poor prognosis in colorectal cancer. All these findings suggest that p73 polymorphism analysis may provide useful prognostic information for colorectal cancer patients.