Identification of ACTL6A-mediated cell growth disruption in gastrointestinal cancer

Abstract

The principle factors fundamental for gastric cancer (GC) development and outcomes are not well characterized resulting in a deficiency of validated therapeutic targets[1]. Previous studies have identified different subordinate groups of GC exhibiting not just genetic, but also distinct epigenetic hallmarks[2]. Accumulating evidence suggests that epigenetic peculiarities in GC are not mere bystanding events, but rather causative agents that advance tumorigenesis through active mechanisms[3]. Identification of the epigenetic modifiers that may participate in the proliferation of GC is the purpose of this study. To reach this goal, I analyzed the data from the GC cDNA microarray (GEO data) in the NCBI database to find the genes with selective GC growth-arrest. Subsequently, I performed CRISPR-Cas9 knockout screening in order to identify the epigenetic modifiers that affect GC cell growth. The analysis of the GEO data showed that Actlin-like 6A (ACTL6A) was up-regulated in GC patients, while the analysis of CRISPR screening indicated that depletion of ACTL6A decreased cell growth. ACTL6A, a component of BAF(SWI/SNF) chromatin remodeling complexes, is important for cell differentiation. Nevertheless, its role and mechanism in GC has not been reported[4]. I investigated the functions and mechanisms of ACTL6A in GC proliferation. The knockout of ACTL6A (ACTL6A-KO) in 4 cell lines gradually decreased cell growth. I also found that the global transcriptional changes incurred following ACTL6A inactivation and the decrease of cell growth was caused by G2M arrest. Considering that the same result occurred not only in the gastric cancer cells but also in the colon cancer cells, the inhibition of ACTL6A promotes decrease of cell growth in gastrointestinal cancer. Therefore, I identified ACTL6A as a candidate oncogenic driver in GC. The direct ACTL6A-regulated mechanisms its involvement in cancer development will be uncovered through further study in progress. Thereby I will suggest ACTL6A as a noble prognostic or therapeutic target in gastrointestinal cancer.