Panoply™ Human SIRT3 Over-expressing Stable Cell Line

Colorectal cancer (CRC) is a prototypical and highly lethal malignancy of the digestive system. Here, researchers investigated the impact of Sirtuin 3 (SIRT3)-a key mitochondrial protein-on CRC cell proliferation, as well as the underlying mechanisms involved. By utilizing data from the University of Alabama at Birmingham Cancer Data Analysis Portal (UAB-CDAP) and the Clinical Proteomic Tumor Analysis Consortium (CPTAC) databases, the researchers discovered that low expression of SIRT3 in CRC serves as an adverse prognostic factor for patient survival. Furthermore, SIRT3 expression levels were found to be closely correlated with distant metastasis and the Tumor-Node-Metastasis (TNM) staging of CRC patients. Compared to control groups, CRC cells stably expressing SIRT3 demonstrated significantly reduced proliferative capacity in both in vitro and in vivo settings. Further in-depth investigations-conducted via Western blotting, immunoprecipitation, and TOPflash/FOPflash assays-revealed that the mechanism underlying this suppression of cell growth is intimately linked to the degradation of cytoplasmic β-catenin and the subsequent translocation of the β-catenin/α-catenin complex into the nucleus. Collectively, these findings suggest that the mechanism by which SIRT3 inhibits CRC cell proliferation is closely intertwined with the inactivation of the Wnt/β-catenin signaling pathway.

To validate the role of SIRT3 in the progression of colorectal cancer (CRC), researchers established stably SIRT3-overexpressing HT29-S3 and HCT116-S3 cell lines. Through Western blot (WB) analysis and SIRT3 enzymatic activity assays, they confirmed the high expression status of SIRT3 protein in these cell lines. Compared to their respective parental cells, SIRT3 expression levels in HT29-S3 and HCT116-S3 cells demonstrated a significant increase in WB detection (Figure 1A). Correspondingly, mitochondrial SIRT3 activity in HT29-S3 and HCT116-S3 cells reached 3.67-fold and 1.58-fold that of their parental cells, respectively (Figure 1B). Furthermore, the proliferative capacity of stably SIRT3-overexpressing HT29-S3 and HCT116-S3 cells was significantly reduced (Figure 1C and 1D). Similar results were obtained when these cells were subcutaneously inoculated into nude mice (Figure 1E-G). The results indicated that in stably SIRT3-overexpressing cells, tumor growth was inhibited, manifested by reduced tumor weight and decreased tumor volume. Notably, compared to the faint expression of SIRT3 observed in HT29 and HCT116 tissues, SIRT3 expression levels in HT29-S3 and HCT116-S3 tumor tissues exhibited a significant increase (Figure 1H, I).

Figure 1. The effect of sirtuin 3 (SIRT3) on the proliferation of colorectal cancer (CRC) cells in vitro and in vivo. (Li T, et al., 2024)