Epigenetic roles of PIWI proteins and piRNAs in lung cancer.

Lung cancer is one of very important malignancies which are related to high mobility and mortality in the world. Despite several efforts for improving diagnosis and treatment strategies of lung cancer, finding and developing new and effective therapeutic and diagnostic are needed. A variety of internal and external factors could be involved in lung cancer pathogenesis. Among internal factors, epigenetic mechanisms have been emerged as very important players in the lung cancer. Non-coding RNAs is known as one of epigenetic regulators which exert their effects on a sequence of cellular and molecular mechanisms. P-element induced wimpy testis (PIWI)-interacting RNAs (piRNAs or piR) is one of small non-coding RNAs that the deregulation of these molecules is associated with initiation and progression of different cancers such as lung cancer. Several activities are related to PIWI/piRNA pathway such as suppression of transposons and mobile genetic elements. In vitro and in vivo studies demonstrated the upregulation or downregulation of PIWI proteins and piRNAs could lead to the increasing of cell proliferation, apoptosis reduction and promoting tumor growth in the lung cancer. Hence, PIWI proteins and piRNA could be introduced as new diagnostic and therapeutic biomarkers in the lung cancer therapy. Herein, we have focused on PIWI proteins and piRNA functions and their impact on the progression of lung cancer.