[Anticancer spectrum of pingyangmycin in vitro].

Pingyangmycin (PYM), produced by Streptomyces pingyangensis n. sp., was found to be identical to bleomycin A5. In the present study, a comparative observation was carried out in 10 human cancer cell lines. As determined by a colony-forming assay, the dose-response curves obtained from cells exposed to PYM for 1 h were of one type only: biphasic exponential. The sensitivities of these cells derived from different types of tumors, however, varied with a broad range of ID50 values (0.03-0.82 microgram/ml). A hepatoma cell line (BEL-7402) and three lines derived from squamous carcinomas of the esophagus (Eca109 and CaEs17) or the nasopharynx (CNE) were relatively sensitive (ID50 less than 0.20 microgram/ml) to PYM which is known to have clinical activity against these diseases. Two gastric adenocarcinoma cell lines (MGc80-3 and BGC-823) and a pulmonary adenocarcinoma cell line (SPC-A-1) appeared to be less sensitive to the drug, with ID50 values of 0.21-0.47 microgram/ml. PYM was 7-fold more effective against LTEP-78 cells derived from pulmonary squamous carcinoma as opposed to SPC-A-1 cells, resulting in a low ID50 value of 0.04 microgram/ml. However, PYM as a single agent has not yet received full evaluation in relation to this type of lung cancer. In contrast with other cell lines of squamous cancer origin, HeLa and CC-801 cells derived from uterine cervix carcinomas which have been evaluated as highly responsive to PYM had the highest ID50 values (greater than 0.70 microgram/ml).