Fundamental and clinical studies on new bleomycin analogs

Peplomycin, a bleomycin derivative, induces myofibroblasts in pulmonary fibrosis

To analyse the mechanism by which a bleomycin derivative, peplomycin (PLM) induces pulmonary fibrosis, we investigated differentiation of rat pulmonary fibroblasts to myofibroblasts (MF). In intraperitoneally PLM (5 mg/kg/day)-injected rats, the peripheries of lungs adjacent to the pleura revealed advanced fibrosis with a small number of alpha-smooth muscle actin (alpha-SMA)-positive MF, which ultrastructurally possessed abundant microfilaments and cellular organelles. In the fibrotic tissue, the expression of alpha-SMA-mRNA was detected by in situ reverse transcription-polymerase (RT-PCR). The message was strong just after a 2-week administration of PLM then decreased thereafter, although fibrosis advanced. When pulmonary fibroblasts were separated from saline-injected rats (N-Fib) and cultivated for 7 days in the presence of 5 mg/mL PLM, alpha-SMA protein was weakly expressed, while the majority of pulmonary fibroblasts separated from PLM-injected rats (P-Fib) became positive for alpha-SMA in 7-day cultivation and the expression of alpha-SMA in P-Fib was strongly increased by cultivation in the presence of PLM and transforming growth factor-beta (TGF-beta), but not basic fibroblast growth factor (bFGF) or platelet-derived growth factor (PDGF), although the cell proliferation was most strongly enhanced by bFGF and only slightly by PLM and TGF-beta. The alpha-SMA-positive cells expressed vimentin, but only weakly expressed desmin. Additionally, P-Fib generated larger amounts of TGF-beta and bFGF than were generated by N-Fib. These results indicate that PLM induces pulmonary fibrosis by differentiating fibroblasts to alpha-SMA-positive MF, and that bFGF and TGF-beta play each critical role in the different phases of PLM-induced pulmonary fibrosis by inducing fibroblast proliferation and transformation, respectively.

Effects of preoperative radiotherapy on rectal cancer. Preliminary report on combining radiation with intratumor injections of peplomycin and bromodeoxyuridine

Between 1976 and 1983, 61 patients with advanced rectal cancer underwent Miles' operation at the authors' institution. All lesions were located 10 cm or less from the anal verge. Of these patients, 25 were treated by surgery alone and 36 were given preoperative radiotherapy. The total dose was 42.6 Gy, (30.6 Gy [1.8 Gy/fr x 5/week]) delivered to the entire pelvis plus an additional 12 Gy (3.0 Gy/fr x 4/week) delivered to the primary tumor. Of 36 patients, 21 were administered intratumor injections of peplomycin and bromodeoxyuridine at the time of boost radiation and 15 were treated without intratumor injections. During the follow-up period (3 to 9 years), in the groups of patients who underwent radiation, there was only one local failure (2.8 percent). In contrast, in the group of patients treated by surgery alone, eight local failures occurred (32 percent). The intratumor injection significantly enhanced the effect of radiation on tumor regression. The incidence of positive lymph nodes was higher in patients in the surgery alone group than it was in the groups treated with radiation. There was no difference in the rate of distant metastasis among the three treatment groups. The five-year survival rate for the radiation with intratumor injection group, radiation alone group, and surgery alone group, was 77.8, 69.2, and 56.0 percent, respectively. No severe complication was experienced.