# Transcriptional Control of Hepatocellular Carcinoma Cells Aggressiveness by AAV2/8-Mediated Delivery of Human Centenarian-Associated SIRT6 N308K/A313S

## TL;DR

A special version of the SIRT6 protein found in centenarians may reduce the aggressiveness of liver cancer cells when delivered via a virus.

## Contribution

This study shows that a centenarian-associated SIRT6 variant suppresses liver cancer cell aggression more effectively than the normal SIRT6.

## Key findings

- The SIRT6 N308K/A313S variant reduces HCC cell proliferation and invasion more than wild-type SIRT6.
- The variant increases cell stiffness, which is linked to less aggressive cancer behavior.
- It modulates genes related to collagen and extracellular matrix remodeling.

## Abstract

Hepatocellular carcinoma, a major type of liver cancer and a leading cause of cancer deaths worldwide, is often linked to poor outcomes due to aggressive cell growth, invasion, and spread. Researchers are exploring ways to slow or stop this aggressiveness using a special variant of the SIRT6 protein, which is found in some exceptionally long-lived people (centenarians). This variant (N308K/A313S) improves DNA repair and fights cancer in other contexts; thus, this study examined whether delivering it to liver cancer cells via a safe viral vector could reduce harmful behaviors compared to the normal SIRT6 version. The findings show that the centenarian variant more strongly curbs cell multiplication and invasion while increasing cell stiffness (a sign linked to less aggressive movement), and that it alters genes related to tissue structure and matrix remodeling. These results suggest that the variant could help suppress liver cancer progression, offering new insights for the research community into potential gene-based therapies for this deadly disease and highlighting SIRT6’s role in cancer control.

Background/Objectives: Hepatocellular carcinoma (HCC) is the sixth 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. Methods: 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. Results: We demonstrate that adeno-associated virus (AAV2/8)-mediated overexpression of centenarian-associated SIRT6 variants hampered HCC cell proliferation, with transcriptomic data showing the modulation of hallmark genes involved in the turnover of collagen/extracellular matrix (ECM). In addition, 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. Conclusions: These data suggest that increased intracellular stiffening mirrors increased cell motility and invasive behavior; it can be indicative of suppressed cancer development and progression by the centenarian-associated SIRT6 N308K/A313S mutant.