GAS 5 Inhibits Gastric Cancer Cell Proliferation Partly by Modulating CDK 6

Gastric cancer (GC) is one of the most common malignant tumors of the alimentary system, especially in East Asian. In 2008, worldwide, approximately 989,600 cases of GC were diagnosed and 738,000 patients with GC died [1]. With the improvement of clinical treatment, the 5-year survival of patients with early GC has significantly increased, but the prognosis of patients with advanced GC is still poor. Hence, early diagnosis and treatment are effective ways to improve the prognosis of GC patients, and it is of vital clinical value to seek novel biomarkers for early diagnosis or therapeutic targets. Aberrant gene expression plays a critical role in the development and progression of cancers. Over the past few decades, researchers have focused on the protein coding genes involved in carcinogenesis. However, recently, non-protein-coding genes have increasingly captured attention because of their key roles in tumor biology. Only less than 2% of the human genome has protein-coding potential, yet more than 90% can be transcribed [2]. Therefore, the vast majority of human genome is transcribed to non-coding RNAs (ncRNAs), such as microRNAs (miRNAs), small interfering RNAs (siRNAs), small nucleolar RNAs (snoRNAs), PIWI-interacting RNAs (piRNAs) and long non-coding RNAs (lncRNAs). MicroRNAs and siRNAs, which belong to the short non-coding RNAs, have been extensively investigated in detail over the past several years; however, lncRNAs, with more than 200 nucleotides (nts), are also attracting the attention of researchers in various fields due to their crucial role in the development and progression of cancers [3]. So far, more than 3,000 lncRNAs that can regulate gene expression at the levels of transcription, post-transcription and chromatin modification have been identified [4, 5]. Studies have demonstrated that the deregulation of lncRNAs was associated with numerous diseases, in