Antimetastatic effect of cell-wall skeleton of Propionibacterium acnes C7 on Lewis lung carcinoma in C57BL/6J mice.

The effect of the cell-wall skeleton (CWS) of Propionibacterium acnes C7 on the metastasis of Lewis lung carcinoma in C57BL/6J mice was examined. Intratumoral or intravenous injection of P. acnes-CWS was effective for both prolongation of the survival period and protection against pulmonary metastases, but intraperitoneal injection was ineffective in tumor-bearing mice. Intratumoral injection of P. acnes-CWS also inhibited lymph node metastases and produced some complete tumor regressions. These cured mice were rechallenged with the same tumor but no evidence of transplantation resistance was found. On the other hand, neither inhibition of lymph node metastases nor complete tumor regressions were observed in the groups treated with intravenous and intraperitoneal injection of P. acnes-CWS. Intrapleural injection of P. acnes-CWS after surgical excision of the primary tumor was also effective for the prolongation of survival period but not for protection against pulmonary metastases.