GSTP1 Ile105Val and GPX1 Pro198Leu Polymorphisms and Their Association with Response to Radiotherapy in Nasopharyngeal Carcinoma Patients

Objectives: Radio-resistance poses a major challenge in nasopharyngeal carcinoma (NPC) treatment. Due to individual variations in radio-sensitivity, biomarkers are needed to tailor radiation treatment. Within this frame, the identification of series of genetic signatures mainly SNPs for NPC patients treated with radiotherapy may help to predict treatment outcome and deliver personalized therapy. The aim of this study was to evaluate the possible association between the GSTP1 Ile105Val and GPX1 Pro198Leu polymorphisms and response to radiotherapy in NPC patients. Methods: From September 2016 to October 2018, a total of 101 patients with confirmed NPC, recruited at Mohammed IV Center for Treatment of Cancer of Casablanca, underwent radiotherapy. DNA was extracted from peripheral blood. Genotyping of the GPX1 Pro198Leu and GPX1 Val105Leu polymorphisms was carried out by PCR amplification and DNA sequencing. SPSS was used to analyse the association of GSTP1 and GPX1 genotypes with clinico-pathological features and response to radiotherapy. Results: The genotyping data revealed the presence of only two genotypes namely Pro/Pro (57.4%) and Pro/Leu (40.6%) for GPX1 gene. The allelic frequencies of C and T alleles were 78.7% and 21.3% respectively. For GSTP gene, the homozygous genotypes Val/Val and Leu/Leu were detected in 35.6% and 12.9% of patients respectively. The heterozygous genotype Val/Leu prevailed (51.5%). Allelic frequencies showed the presence of the two alleles A and G in 57.1% and 42.9% patients respectively. Statistical analysis failed to find any significant association between GSTP Val105IIe and GPX1 Pro198Leu genetic polymorphisms and socio-demographic and clinico-pathological features as well as response to radiotherapy (p>0.05). Conclusion: Further research is warranted on the potential role of SNPs within antioxidant defines genes in radiotherapy response and to identify reliable predictive and non-invasive biomarkers for radio-resistance among NPC patients for personalised therapies.