Transcriptional control of hepatocellular carcinoma cells aggressiveness by AAV2/8-mediated delivery of human centenarian-associated SIRT6 N308K/A313S

Hepatocellular carcinoma (HCC) is the 6th most prevalent cancer and a chief cause of cancer-related mortality throughout the world. SIRT6 is a fundamental sirtuin that governs several disease processes encompassing inflammation and cancer, including HCC. Longevity in centenarian Ashkenazi Jews was recently associated to novel allelic variants of SIRT6 (N308K/A313S), which ameliorate genome maintenance and DNA repair, and suppress cancer cells. It is currently unknown whether the above-mentioned SIRT6 variants display divergent or similar roles in HCC pathogenesis, compared to the wild type (WT) counterpart. In this work, our goal was to elucidate how these new centenarian-associated SIRT6 genetic variants may modulate HCC cell lines (HepG2 and Huh-7) aggressiveness and behavior, using functional and transcriptomic approaches. We demonstrate that adeno-associated virus (AAV2/8)-mediated overexpression of centenarian-associated SIRT6 variants hampered HCC cells proliferation, with transcriptomic data showing modulation of hallmark genes involved in the turnover of collagen/extracellular matrix (ECM). Also, we found that AAV2/8-mediated overexpression of SIRT6 N308K/A313S decreased invasion and also increased stiffness in HCC cells, as measured by nanoindentation, in a more pronounced fashion compared to SIRT6 WT. Intracellular stiffness is a property of the cancer cells themselves, which, along with ECM invasiveness, plays a significant role in the progression of HCC. In conclusion, these data suggest that increased intracellular stiffening mirror increased cell motility and invasive behavior, and it can be indicative of suppressed cancer development and progression by centenarian-associated SIRT6 N308K/A313S mutant.