PIWI-Interacting RNAs in Gliomagenesis: Evidence from Post-GWAS and Functional Analyses

PIWI-interacting RNAs (piRNAs), the largest class of noncoding RNAs in mammals, cooperate with PIWI proteins to safeguard the genome from insertional mutations during germline development. Although a growing number of studies have linked the PIWI-piRNA pathway to carcinogenesis, the role of piRNAs in glioma has not been explored.

Utilizing directly measured and imputed genotypes from the GliomaScan genome-wide association study (1,840 cases and 2,401 controls), genetic variants in 1,428 piRNAs were analyzed for association with glioma risk. In vitro assays were performed to interrogate the functional impact of a top identified piRNA and its variant allele.

Variants in five piRNAs were considered to be associations of interest and four of these showed narrow clusters of enhanced association signals surrounding the index variant. Functional analyses of one of these piRNAs, piR-598, revealed that transfection of the wild-type piRNA impacted expression of genes involved in cell death/survival and reduced glioma cell viability and colony formation. However, upon delivery of piR-598 containing the variant allele at rs147061479 [OR, 1.80; 95% confidence interval (CI), 1.33-2.46; P = 1.69 × 10(-4)], cell proliferation was sharply increased.

The genetic association analysis identifies several piRNAs associated with glioma risk, and follow-up functional analyses suggest that variant rs147061479 in piR-598 increases glioma risk by abolishing the tumor-suppressive function of piR-598, instead conferring growth-promoting properties.

This transdisciplinary study demonstrates a role of piRNAs in gliomagenesis by evidence from both post-GWAS and in vitro functional analyses and supports expanded investigation into the link between the PIWI-piRNA pathway and cancer. Cancer Epidemiol Biomarkers Prev; 25(7); 1073-80. ©2016 AACR.