Effect of bacterial lipopolysaccharide on growth of murine bladder cancer, MBT-2.

Intradermal palpable MBT-2 tumor responded with bacterial lipopolysaccharide to hemorrhagic necrosis (LPS) in C3H/HeN (endotoxin sensitive) mice. We have tested LPS fractions isolated from E. coli, Klebsiella pneumoniae, Salmonella minnesota, Pseudomonas aeruginosa and Serratia culture filtrates. All these LPS preparations showed tumor necrotizing activity accompanied by toxicity (body weight loss) in C3H/HeN mice. However, MBT-2 tumors grown in an endotoxin-resistant strain (C3H/HeJ) of mice did not respond to LPS, even at a very high dose. In vitro, the LPS showed no cytotoxic effect on MBT-2 cells. For comparison, systemic administration of tumor necrosis factor (cachexin ) did not affect the i.d. tumor growth. These data indicate that host reactions to LPS (endotoxicity) plays a pivotal role in the expression of tumor necrosis. Accordingly, comparisons of tumor response between endotoxin sensitive and resistant mice avoid potential overestimation of the therapeutic value of certain bacterial products and/or LPS contaminated agents.