Bactofection of SW620 cell by Lactococcus lactis M4

Abstract

In this study, a local dairy isolate, L. lactis M4 was investigated for its ability to be developed as a live delivery vector to deliver plasmid DNA into human colon cancer cell line, SW620. L. lactis M4 strain was found to adhere to and internalize SW620 cells optimally after 2 hours of infection period at a multiplicity of infection 250:1, bacteria per cancer cell. Bacteria also managed to survive intracellularly for 7 hours. Entry into SW620 cells was inhibited by Cytochalasin D and Vinblastine, indicating that cell uptake was dependent on microfilament and microtubule stability. Bactofection of SW620 cells by L. lactis M4 was demonstrated through the expression of fluorescent proteins from a novel dual-expression plasmid, pHSR. L. lactis M4 was able to express red fluorescent protein intracellularly of SW620 cells, which were subsequently observed to express green fluorescent protein at 3 hours post-invasion. The expression of fluorescent proteins from pHSR resulted from the bactofection of SW620 cells by L. lactis M4 has proven that this strain can be developed as a vector to deliver plasmid DNA into the cancer cell.

Adherence and internalisation of Lactococcus lactis M4 towards human colorectal cancer cell line, Caco-2

“…By avoiding the use of genetic modifications, this approach is expected to comply with the United States Food and Drug Administration (USFDA) requirements for future applications of this strain in human. Findings from this study are also coherent with another study, which also reported on the ability of this local strain to display bacterial interaction with human colorectal cancer cell line, SW620 cells (Faroque et al, 2018). According to Faroque et al (2018), L. lactis M4 showed significantly greater rate of bacterial adherence and internalisation in comparison to an established probiotic strain, Lactobacillus reuteri CI.…”