Enhanced antimicrobial and anticancer properties of penicillin G-adapted Lacticaseibacillus rhamnosus GG against colorectal cancer cells.

BACKGROUND

Colorectal cancer (CRC) is one of the most prevalent cancers globally, ranking third in women and fourth in men, and accounts for approximately 10% of cancer-related deaths. Antibiotic therapy and chemotherapy are common treatments for intestinal diseases and CRC, but they can affect the gut microbiota and cause dysbiosis. Probiotics are vital for maintaining a healthy gut microbiota and preventing dysbiosis. Lacticaseibacillus rhamnosus GG (L. rhamnosus) is well-known for its antimicrobial and anticancer properties.

METHODS

In the present study, we aimed to investigate the effects of long-term penicillin G treatment on the antimicrobial and anticancer properties of L. rhamnosus. Initially, an antibiotic-resistant L. rhamnosus was created by the adaptation process. The acid tolerance of both antibiotic-resistant and normal strains was assessed. The antimicrobial properties of the cell-free supernatants (CFS) from both untreated and penicillin G-treated strains (Pen(G)-CFS) on different species of pathogenic bacteria, including Staphylococcus epidermidis (CoNS), Staphylococcus aureus, Enterococcus faecalis, Salmonella typhi, Escherichia coli, and Pseudomonas aeruginosa were investigated. To assess the anticancer effects of these supernatants on HT-29 CRC cells, various cellular and molecular assays, including MTT, apoptosis (Annexin V/PI staining), cell cycle, scratch, and colony formation assays, quantitative real-time PCR (qRT-PCR), and Western blot were performed.

RESULTS

Our results demonstrated no significant difference in proliferation between the two strains in acidic conditions. Interestingly, Pen(G)-CFS exhibited a significantly stronger antimicrobial effect against pathogenic bacteria compared to the CFS. The results of cellular experiments showed that treating HT-29 cells with Pen(G)-CFS compared to CFS could significantly inhibit proliferation. Additionally, this treatment increased the rate of apoptosis, arrested the cell cycle in the sub-G1 phase, and suppressed cell migration and colony formation ability. These findings were confirmed using qRT-PCR and western blot analysis, which revealed Pen(G)-CFS could considerably modulate the expression of genes and proteins (BAX, BCL2, CASP3, CASP9, MMP3, MMP9) compared with CFS.

CONCLUSIONS

Our results suggest that antibiotic-resistant L. rhamnosus not only retains probiotic properties but also exhibits enhanced antimicrobial and anticancer activities compared to the normal strain. This approach holds promise for reducing the adverse effects of antibiotics and chemotherapy on the gut microbiota and may offer a novel strategy for improving patient outcomes in CRC treatment.