PIWI-Interacting RNAs in Oral Cancer: Paradigm Shift in Prognosis and Diagnosis

Oral squamous cell carcinoma (OSCC) is the most prevalent cancer in Indian subcontinent with high recurrence rate, aggressive metastasis, and poor prognosis. The potential risk-factors for OSCC are tobacco smoking, alcohol intake, and persistent infection of oncogenic human papillomaviruses (HR-HPVs). HPV-positive OSCCs show distinct genetic and epigenetic changes along with distinct clinical, epidemiological and molecular characteristics. Recently, with the accumulation of large amount of genomic and epigenomic data, there is an increasing focus on epigenetic alterations playing key roles in cancer pathogenesis. Non-coding RNAs, especially the small noncoding RNAs (sncRNAs) have gained attention since they have been demonstrated to fine tune transcription via alterations in the epigenetic landscape. There are ample evidences supporting the role of small non-coding RNAs such as miRNAs and piRNAs in development and disease including cancers. PIWI-interacting RNAs (piRNAs), a class of sncRNAs are emerging players involved in transcription silencing. Its altered regulation is associated with the development of variety of tumors including oral carcinogenesis; however, their tumor specific roles are not fully understood. Therefore, identification and comprehensive characterization of oncogenic as well as tumor suppressive pi-RNAs and dissecting their roles in tumorigenesis is of great importance in the field of cancer biology. Furthermore, piRNAs may potentially serve as unique therapeutic targets and/or molecular markers for early detection and effective treatment of OSCC subtypes. In this mini review, we briefly summarize the emerging role of PIWI-RNAs in oral cancer.