Background: Piwi-like gene family members (Piwil 1-4) are considered stem cell-associated genes/proteins. These are expressed predominantly in germline cells, but are re-expressed in different tumors. Piwil 1-4 gene expression has not previously been studied and correlated with clinicopathological parameters in renal cell carcinomas (RCC).

Material and Methods: The Piwil 1-4 transcript levels were analyzed by quantitative real-time PCR in 74 clear cell RCC (ccRCC) tissues and corresponding normal tissues.

Results: The transcript levels of Piwil 1, 2 and 4 were strongly and significantly correlated with each other, but not with Piwil 3, in both the tumor tissues and the normal tissues (P < 0.001; Spearman's rank test). Piwil 4 gene expression was significantly higher in the ccRCC tissues than in the corresponding normal renal tissues (P < 0.001; Wilcoxon signed-rank test). When the ccRCC patient cohort was divided according to the median Piwil 1-4 expression into low and high-expression groups and according to age into younger (≤ 64 years) and older patient groups (>64 years), the younger patients displayed significantly higher levels of Piwil 1 mRNA in comparison to the older patients (P = 0.010; Fisher's exact test). Interestingly, Piwil 1 expression was left-right polarized in the normal tissues but not in the tumor tissues (P = 0.0005; Fisher's exact test).

Conclusions: Altogether, associations were determined between the Piwi-like family member expression levels and clinicopathological parameters of ccRCC, suggesting a potential role for these genes/proteins in ccRCC diagnostics and tumorigenesis, as well as in renal tissue embryology.

Citation Format: Omar Al-Janabi, Sven Wach, Elke Nolte, Katrin Weigelt, Tilman T. Rau, Christine Stöhr, Wolfgang Legal, Stefan Schick, Thomas Greither, Arndt Hartmann, Bernd Wullich, Helge W. Taubert. Piwi-like 1 and -4 gene transcript levels are associated with clinicopathological parameters in renal cell carcinomas. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1853. doi:10.1158/1538-7445.AM2014-1853