In a study in 2014, the anti-cancer effects of bacterioicin isolated from Enterococcus Mundtii strain C4L10 was evaluated. It was showed that this bacteriocin has anti-proliferative activities against different human cancer cell lines. 16
In a study conducted by Ankaiah et al. the bacteriocin enterocin-B produced by E.faecium exhibited anti-cancer activity against HeLa, HT-29, AGS cancer cells and it was observed that the anti-cancer activity was dramatically increased when cancer cells treated with the heterodimer of the bacteriocins enterocin-A+B. 17
Nami et al. evaluated the therapeutic effects and probiotic properties of proteins secreted by Ent. faecalis. In this experiment, the anti-cancer effect of enterocin on four human cancer cell lines (AGS, HeLa, MCF-7 and HT-29) as well as a normal cell line (HUVEC) was investigated. Their findings revealed that the metabolites produced by this vaginal Ent. faecalis strain can induce the apoptosis of cancer cells.18
In a study by Abdi-Ali et al., the cytotoxic effect of pyocin S2, derived from Pseudomonas aeruginosa, on the human tumor cell lines HepG2 and Im9 and the normal human cell line HFFF was surveyed. Indeed the results indicated that pyocin S2 exhibit an inhibitory effect on tumor cell lines.19 In another similar study, the cytotoxicity of pyocin S2 was evaluated against human malignant cells and normal cells in the same species. According to the results, the inhibitory effects on the cells increased with an increase of pyocin S2 activity. 20
Kim and colleagues examined the anticancer effect of cytoplasmic fraction from Lactococcus lactis ssp. lactis. The results of these researchers indicated the proliferation of human colon cancer cell line was inhibited by the treatment with cytoplasmic fraction of Lc. lactis.21
In another study in 2020, PI staining was performed and revealed apoptosis in Colicin N-treated cells, but no detectable fluorescent red was associated with necrosis.22
In a study by Chumchalova et al., considered colicin E1, A and U stopped the cell cycle in five tumor cell lines. Colicin E1 and A, induced apoptosis in three cancer cell lines by 7 to 58%.23
Ankaiah et.al studied the anti-cancer activity of enterocin-A against human colon, gastric (HT-29, Caco-2 and AGS) and cervical (HeLa) cancer cell lines and they found out that ent-A was able to induce apoptosis in HeLa cell line at a concentration of 120μg/ml, so that 53.93% of the cells had delayed apoptosis and 5.8% showed a primary apoptosis.24
Fathizadeh et al. in a review study investigated the role of bacteriocins as new potential therapeutic candidates in cancer therapy. They find out that Evidence suggests that bacteriocins such as colcins, nisins, pediocins, pyocins, and bovocins are able to inhibit tumor growth at various stages by activating or inhibiting various cellular and molecular signaling pathways.25 They also showed that enterocin A-colicin E1 fusion peptide can be used as an effective antibacterial compound to treat or prevent bacterial infections.26
Jalalvand et al. were investigated cloning and expression of the fusion gene construct of enterosin A, pyocin R, and lactocin, along with the anticancer peptide and specific ligand of the AGS cell line in a bacterial host. When this recombinant protein was exposed to AGS cell line, it resulted in a significant increase in the expression of Bax and caspase 3 genes and a significant decrease in Bcl2 gene expression compared to the GAPDH reference gene.27
In our study, the anticancer effect of peptide fusion, bacteriocins and specific ligand of AGS cell line were investigated. In general, the recombinant protein induced apoptosis in the AGS cell line, and it can be suggest that this recombinant protein activated apoptosis internally, leading to cell death.
Flow cytometry results showed that the frequency of cancer cells treated with recombinant protein that had apoptosis was significantly higher than untreated cells. This indicates that treatment of AGS cell line with recombinant protein at a concentration of 80μg/ml induces apoptosis.
Under certain conditions, this recombinant protein may be used as adjuvants in chemotherapeutic drug combinations or as a tool to manipulate the expression of genes induced in apoptosis and ultimately control the growth and proliferation of cancer cells.
Through the present study, the following findings were specifically obtained:
- Tests to measure the ability to inhibit cell proliferation and induce apoptosis in the cancer cell line showed that recombinant protein at a concentration of 80μg/ml can induce apoptosis and death in the gastric cancer cell line.
- In general, recombinant protein may be introduced as a candidate to control microbial infections as well as cancer, and further attention and research.
These results can be the basis for more extensive studies to comprehensively study the effects of this recombinant protein for use in the treatment of cancer. In vitro results show that this protein has the necessary properties for in vivo studies.