Designing a light-activated recombinant alpha hemolysin for colorectal cancer targeting

Colorectal cancer (CRC) is one of the main health burden worldwide, which can cause major economic and physiological problems along with relatively high rate of mortality. It is important to develop new methods for the localized delivery of recombinant protein therapeutics, in large part due to the failure of conventional therapies in most cases. Since E. coli Nissle 1917 (EcN) does not produce any virulence factors, here we used these bacteria with the light-activated promoter system to deliver therapeutic agents in the desired location and time. In this study, Staphylococcus aureus alpha hemolysin (SAH), after codon usage optimization, was cloned into blue light activating vector (pDawn) and transferred to EcN strain. Then, the functionality and cytotoxicity of secreted alpha hemolysin was evaluated in the SW480 colon cancer cell line by using different experiments, including blood agar test, flow cytometry analysis, and DAPI staining. Our findings revealed that EcN can produce functional SAH under the blue light irradiation against SW480 cancer cells. Moreover, cytotoxicity assays confirmed the dose- and time-dependent toxicity of this payload (SAH) against SW480 cancer cells. Based on our results, EcN is proposed as an appropriate light-activated vehicle for delivery of anticancer agents to the target cancer cells/tissues.