Lactobacillus species is more cytotoxic to human bladder cancer cells than Mycobacterium Bovis (bacillus Calmette-Guerin).
OBJECTIVE
We determined if Lactobacillus species has growth inhibitory effects in human bladder cancer cell lines and how this effect compares with the known effects of Mycobacterium bovis, that is bacillus Calmette-Guerin (BCG).


METHODS
The growth of MGH and RT112 cells were determined by cell counts after 24, 48 and 72 hours of exposure to L. casei strain Shirota (Yakult, Singapore) or L. rhamnosus strain GG (National Collection of Industrial and Marine Bacteria, Ltd., Aberdeen, Scotland) (1 x 10 and 1 x 10 cfu) or BCG (1 x 10 cfu) in the presence and absence of streptomycin. Annexin-V was used to monitor the presence of pre-apoptotic cells.


RESULTS
L. rhamnosus GG inhibited MGH proliferation and it was cytotoxic to RT112 cells (p <0.05). L. casei Shirota was cytotoxic to the 2 cell lines (p <0.05). BCG had a similar cytotoxic effect in MGH cells as Lactobacillus species but was not as effective in RT112 cells. Streptomycin abrogated the cytotoxic effect of Lactobacillus species but not that of BCG. Cytotoxic activity was not found in Lactobacilli culture supernates but it was induced in the presence of mammalian cells. L. rhamnosus GG induced apoptosis in RT112 but not in MGH cells. No apoptotic cells were detected after treatment with L. casei Shirota.


CONCLUSIONS
Lactobacillus species induced cytotoxic effects in bladder cancer cells. Unlike BCG, it requires bacterial protein synthesis. Like BCG, L. casei Shirota induces cell death primarily via necrosis. The cytoxicity of these lactobacilli in bladder cancer cells raises the possibility of using this species of bacteria as intravesical agents for treating bladder cancer.
Seow
Shih Wee
SW
Department of Microbiology, National University of Singapore, Singapore.
Rahmat
Juwita Norasmara Bte
JN
Mohamed
Ameer Ali Kanakkappillai
AA
Mahendran
Ratha
R
Lee
Yuan Kun
YK
Bay
Boon Huat
BH
D001500:BCG Vaccine / Q000276:immunology / Q000494:pharmacology*; D002455:Cell Division / Q000276:immunology*; D002470:Cell Survival / Q000276:immunology; D003601:Cytotoxicity Tests, Immunologic; D006801:Humans; D007780:Lacticaseibacillus casei / Q000276:immunology*; D014407:Tumor Cells, Cultured / Q000276:immunology*; D001749:Urinary Bladder Neoplasms / Q000276:immunology*
D001500:BCG Vaccine