Prodigiosin, a biocolorant produced by <i>Serratia marcescens</i> , interferes with apoptosis and MAPK-ERK1/2 signaling in the A-431 skin cancer cell line

Purpose The red pigment prodigiosin, produced by the bacterium Serratia marcescens, exhibits antimicrobial, anticancer and antifouling activities. This study aims to evaluate the anticancer effects of this pigment on skin cancer cells. Design/methodology/approach MTT assay was used to assess the pigment’s cytotoxicity against A-431 skin cancer cells and normal human dermal fibroblasts (HDF). Furthermore, the pigment’s ability to induce apoptosis in cancer cells was investigated using flow cytometry. The expression levels of genes involved in the apoptosis and MAPK-ERK1/2 signaling pathways were assessed by real-time PCR. Findings The pigment demonstrated potent cytotoxicity against cancer cells with half maximal inhibitory concentration (IC50) values of 0.010 mg/mL at 24 h and 0.002 mg/mL at 48 h, compared to significantly higher IC50 values for normal cells (0.175 mg/mL and 0.040 mg/mL, respectively). Flow cytometry revealed a marked reduction in viable cancer cells, from 95.08% in the control group to 66.4% in the treated group (p &amp;lt; 0.001). Early apoptotic cells increased from 0.58% to 16.6% and late apoptotic cells rose from 0.79% to 12.4% following treatment (p &amp;lt; 0.001). Gene expression analysis showed upregulation of apoptosis-related genes caspase-3 and caspase-8, while RAF-1 and ATF4 expression levels were significantly downregulated in cancer cells treated with the pigment (p &amp;lt; 0.05). Originality/value In this study, prodigiosin has been found to exhibit cytotoxicity and apoptosis-inducing properties in A-431 skin cancer cells. The low toxicity of prodigiosin to normal cells can make it an attractive candidate for further therapeutic research.