Lactobacillus: An alternative immunotherapy for bladder cancer
Authors: Seow Shih Wee, Lee Yuan Kun, Bay Boon Huat, Ratha Mahendran
Journal: Clinical Cancer Research (2007)

AACR Centennial Conference: Translational Cancer Medicine-- Nov 4-8, 2007; Singapore

B31 

Bacillus Calmette-Guerin (BCG) instillations after surgery is the gold standard in treating superficial bladder cancer, but there are many side-effects. Consumption of Lactobacillus spp. can prevent bladder cancer and delay disease progression; however, its mechanisms are not thoroughly understood. Hence, this study examined the efficacy of L.rhamnosus GG (LGG) as an adjuvant immunotherapeutic agent as well as its possible anti-tumour mechanisms.    Bladder tumour was induced in female C57BL6 mice (4 - 6 weeks). The mice were then given 6 weekly intravesical instillations of live LGG; lyophilised LGG (Lyo LGG); and a 3rd group (O+I) was fed live LGG a day before scheduled Lyo instillation;. Control mice were treated with PBS. Mice were sacrificed 24hr after the 6th instillation. Spleens and draining lymph nodes were harvested for FACS; bladders were analysed for cytokines. The human bladder cell line MGH was treated with LGG and harvested for cell cycle and NAG-1 mRNA analysis. Western blot analysis to characterise caspase-3activation fragments generated in MGH under basal conditionsand after treatment with live or lyo LGG was also performed.    LGG instillations conferred survival advantage over controls with 30% clinical significance. All three forms of LGG therapy had a protective effect over PBS; Live GG: OR = 0.284, 95% CI 0.090 - 0.897, p = 0.032; Lyo LGG: OR = 0.402, 95% CI 0.168 - 0.963, p = 0.041; O+I: OR = 0.264, 95% CI 0.084 - 0.826, p = 0.22. Oral administration of LGG did not augment intravesical LGG therapy.    The spleen T-helper cell population in the O+I mice was significantly elevated after 6 weeks of therapy, while the B-cell and Ly6G positive cells in the spleen and lymph nodes were reduced compared to controls. Also, intravesical instillations of LGG elevated LGG-protein specific IgG, the raised titre did not correlate with the anti-tumour response.    Using the antibody cytokine array, pro-MMP9, osteopontin, E-selectin, VEGF-D, VEGF-R2 and Xcl1 were found to be differentially expressed in the control and cured bladders. It was confirmed with ELISA that tumour-bearing bladders had significantly more osteopontin, pro-MMP9 and E-selectin than cured bladders, irrespective of the treatment administered.    Both live and lyo LGG could induce apoptosis in MGH cells after 72hr. LGG was also found to induce and increase NAG-1 mRNA and protein levels in a time-dependent manner, reaching the maximum level (mRNA and proteins) 72hr after treatment.    All 3 types of LGG preparations are equally efficacious as intravesical immunotherapeutic agents. It is likely that LGG mediated anti-tumour effects via apoptosis and not through systemic immune response. NAG-1 protein has been shown to possess antitumorigenic and proapoptotic activities in vitro and in vivo. The increase in NAG-1 mRNA led to a corresponding decrease in caspase 3 proteins but increased the amount of cleaved caspace-3 fragments.