Effect of some aspirin analogues on SW480 Colorectal cancer cell line: Tip of the iceberg

Abstract

Abstract

Colorectal cancer (CRC) is the third most common cancer and second leading cause of death with approximately 1.9 million cases and  almost a million deaths worldwide in 2020. It is predicted that the global incidences of CRC will be over 3 million in 2040. Aspirin has been shown to have cytotoxic and immunomodulatory effects on CRC cell lines. However, due to side effects such as gastrointestinal bleeding in older patients, there has always a quest for safer and more effective analogues, leading to the synthesis of aspirin analogues. One of the primary regulators of the mitochondria-mediated pathway to apoptosis is the family known as BCL-2 proteins, which are broadly grouped into pro-apoptotic proteins such as BAX, BAK, BIK, BAD and anti-apoptotic proteins such as BCL-2 and BCL-X_L.

Phase contrast images of the SW480 CRC cells treated with aspirin, meta-aspirin, para-aspirin, ortho-thioaspirin, meta-thioaspirin and para-thioaspirin at 0.5 mM for 24 h, 48 h and 72 h were taken at 100X magnification.

Western blot was used to detect BAX and BCL-2 proteins by treating CRC cells with aspirin and its analogues, and analysed by SDS-PAGE and immunoblotting. The blots were then probed with primary antibodies BCL-2 and BAX, after which the HRP bound protein-labelled antibody was visualised using ECL and exposed to CL-XPosure™ Film.

It was observed that the isomers of aspirin (O-ASP), meta-aspirin (M-ASP) and para-aspirin (P-ASP) significantly increased the density of BAX Ab. O-ASP, M-ASP, P-ASP and ortho-thioaspirin (O-TASP) significantly reduced the density of BCL-2 Ab, thus proposing that the anti-apoptotic effect of this cell line is reversed/reduced by these aspirin analogues.

The results of this study suggest that M-ASP and P-ASP have its antiproliferative effect on the SW480 CRC cell line via driving the pro-apoptotic effect of BAX protein and decreasing the expression of anti-apoptotic of BCL-2 protein, thus, encouraging apoptosis in this CRC cell line.