Streptococcus-derived CpsA–CpsC fusion protein induces apoptosis in cervical cancer cells through in silico and in vitro methods

Cervical cancer is a significant cause of cancer-related mortality in women, and the toxicity of conventional anticancer drugs has necessitated the development of novel therapeutic strategies. In the present study, we designed a fusion protein containing CpsA and CpsC proteins encoding capsular polysaccharides in Streptococcus agalactiae and evaluated its potential anticancer activity. Physicochemical properties, 3-dimensional (3D) structure, and molecular dynamics (MD) simulation were analyzed using in silico tools. Then, the recombinant gene was cloned, expressed in a bacterial host, and purified successfully. Finally, the anticancer effects of the CpsA-CpsC fusion protein on cervical cancer cell line (HeLa) were evaluated through MTT, Real-Time PCR, and flow cytometry techniques. Functional assays demonstrated that the CpsA-CpsC fusion protein exerted time- and dose-dependent cytotoxic effects on HeLa cells, with an IC50 value of 68.1 µg/mL at 48 after 48 h of treatment. Flow cytometric analysis using Annexin V/PI staining revealed a significant increase in apoptotic cell populations (17.5%). Furthermore, gene expression analysis revealed marked upregulation of the pro-apoptotic genes, Bax (22.62-fold) and Caspase-3 (22.06-fold), along with a downregulation of the anti-apoptotic gene, Bcl-2 (0.235-fold), supporting apoptosis as a potential mechanism of cell death. These findings suggest that the CpsA-CpsC fusion protein may exert apoptotic effects in cervical cancer cells and provide a basis for further investigation of bacterial-derived components as candidate anticancer agents.