The potentiation of the antitumor activity but not toxicity of bleomycin by 3-aminobenzamide

Our previous studies have demonstrated that 3-aminobenzamide (3AB), an inhibitor of adenosine diphosphate-ribosyl transferase (ADPRT) could enhance the cytotoxicity (in vitro) and antitumor activity (in vivo) of bleomycin (BLM) A5 and peplomycin (PEP) against S-180, hepatoma and Ehrlich ascites carcinoma (EAC). In this study, it was shown that the inhibition rates (INR's) of S-180 in two experiments were increased from 42.5 and 46.1% to 66.2 and 75.9% when BLM 2.5 mg/kg/day x 8 was combined with 3AB 385.4 mg/kg/day x 8, while the decrease of body weight could not be enhanced. BLM at a dose of 5 mg/kg/day x 8 gave INR's of 64.8 and 75%, similar to the combined group but decreased the body weight more significantly. However, the addition of 3AB 385.4 mg/kg/day to BLM did not increase the acute toxicity of BLM alone. There was no significant difference of change of the body weight and subacute toxicity between the BLM and BLM + 3AB group. There was no difference of peripheral blood white cell count and the pathomorphological and ultrastructural change, wet weight and hydroxyproline content (to reflect the collagen content) of the lung of the mice between BLM alone and BLM + 3AB group. Therefore, the study provided experimental evidences for the reasonable use of nontoxic ADPRT inhibitors in adjunct to the chemotherapy of BLM in cancers.     

Genotoxicity of bleomycin in human cell lines differing in catalase activity

The influence of catalase on the genotoxic effect of bleomycin (BLM) has been evaluated in three cell lines which differ in catalase activity. CRL1307, cells from Xeroderma pigmentosum patient and CLV102, normal embryonic cells have catalase activity 3.5 and 5 times lower then CRL2088, normal skin fibroblasts. Genotoxicity of BLM (0.5-50 micrograms/ml, 2 h treatment) measured with in vitro micronucleus test did not differ in three tested lines. BLM at concentration range from 1 to 25 micrograms/ml (2 h treatment), tested in comet assay, caused similar degree of DNA damage in CLV102 and CRL2088 cells. Exogenous catalase (300 and 900 u/ml) added to the assay medium with BLM did not influence the micronuclei induction. The absence of endo- and exogenous catalase influence on BLM genotoxicity suggests that not hydrogen peroxide but other reactive oxygen species are formed in reaction of activated BLM with molecular oxygen.     

The use of uninduced rat liver S-9 to supplement BALB/3T3 cells in the in vitro transformation assay

Because of limited inherent capacity to metabolize chemicals to their reactive form, the BALB/3T3 transformation assay using clone A31-1-1 cells requires metabolic supplementation with rodent liver homogenate preparations (S-9). Activation by S-9 is limited, however, by its cytotoxicity to the cells, thus necessitating a reduction in treatment time from the usual 24-72 to 1-4 hr. With cyclophosphamide (CP) as a test chemical, we were able to increase the treatment time to 24 hr by using lower concentrations of cofactors and S-9 prepared from the livers of untreated rats. Statistically significant increases in transformed foci were induced in cultures treated with 50 or 100 micrograms CP/ml in the presence of 100 or 200 micrograms of uninduced rat liver S-9/ml and 76 or 380 micrograms each of NADH, NADP, NADPH, and glucose-6-phosphate per ml of incubation medium.     

银杏黄酮类物质抗肿瘤作用初探

目的探测银杏黄酮类物质的抗肿瘤作用。方法微核检测法测定银杏黄酮对致畸作用的防护;H3标记法检测银杏黄酮对体外培养的YAC-I细胞增殖的影响;原位注射法检测银杏黄酮对小鼠体内S-180实体瘤生长的影响。结果银杏黄酮处理组小鼠的微核率明显低于对照组,抑核率为48.23%;YAC-I细胞在银杏黄酮作用24h和48h后,增殖受到明显抑制,浓度为2500μg/ml时,增殖基本停滞;荷瘤小鼠在接受原位注射银杏黄酮后,肿瘤生长受到明显抑制,抑瘤率为56.99%。结论银杏黄酮可防护环磷酰胺的致畸作用;对体内体外肿瘤细胞的增殖均具抑制作用。     

Platelet-derived growth factor (PDGF) accelerates induction of competence, and heparin does not inhibit PDGF-induced competence in primary cultured smooth muscle cells of rat aorta.

The time-dependent effect of platelet-derived growth factor (PDGF) on cell proliferation was investigated to clarify whether PDGF accelerates the rate of proliferation or its start in primary cultured smooth muscle cells (SMC) of rat aorta. In synchronized SMC at the G0 phase, 1, 10 and 100 ng/ml PDGF started DNA synthesis at 24, 15-18 and 12 hr, respectively, after stimulation by 3% fetal bovine serum (FBS) or hypophysectomized rat plasma (deficient in insulin-like growth factor-I (IGF-I)). Heparin (1, 10 or 100 micrograms/ml) decreased only the rate of DNA synthesis stimulated by PDGF in synchronized SMC. DNA synthesis in non-synchronized cells stimulated by PDGF with FBS was determined up to 10 days in culture. The stimulation with 1% FBS plus 30 ng/ml PDGF potentiated the DNA synthesis which was saturated with stimulation by 10% FBS alone, suggesting that prolonged treatment of PDGF transforms SMC. These results demonstrated that PDGF concentration-dependently accelerated the induction of competence independently of IGF-I, and heparin did not inhibit PDGF-induced competence but inhibited progression in primary cultured SMC of rat aorta.     

In vitro interaction of mezlocillin with fluorouracil and mitomycin

The interaction of mezlocillin (Baypen) with either fluorouracil (5-fluorouracil, 5-FU) or mitomycin was tested in vitro by incubating colorectal carcinoma cell line HT 29 with varying concentrations of mezlocillin, 5-FU, mitomycin and the combinations of mezlocillin + 5-FU and mezlocillin + mitomycin. Inhibition of colony growth in soft agar of treated compared with untreated cells was used as an in vitro response parameter. Concentration ranges were representative for regional chemotherapy with mitomycin or 5-FU and perioperative antibiotic therapy with mezlocillin. Mezlocillin, 5-FU and mitomycin showed dose-dependent inhibition of colony growth. Mezlocillin produced a maximal toxicity of 16% at 1000 micrograms/ml. Toxicity of 5-FU was reduced by addition of mezlocillin. The increase of colony growth after coincubation of mezlocillin with 5-FU (compared to cells treated with 5-FU alone) at a mezlocillin concentration of 10 micrograms/ml was 47% to 116%, at 100 micrograms/ml 44% to 132%, depending on the 5-FU test concentrations. The 5-FU toxicity in some instances was nearly abolished. There was no interaction between mezlocillin and mitomycin. The interference of mezlocillin with 5-FU-toxicity should be respected in case of combined perioperative antitumor and antibiotic therapy with 5-FU mezlocillin. Similar interactions with related antibiotics cannot be excluded.     

Effects of Tremella polysaccharides on immune function in mice

It was found in vitro that Tremella polysaccharides (TP) (50, 100, 150 and 200 micrograms/ml) augmented lymphocyte proliferation induced by Con A and did not antagonize the suppressive effect of hydrocortisone on lymphocyte proliferation. In vivo TP promoted the plaque-forming cell (PFC) response to SRBC in mice. TP 50 and 100 mg/kg ip for 5 d produced 77.6% and 81.8% increases in PFC response respectively. At the doses of 150 and 200 micrograms/ml, TP decreased the interleukin 2 (IL-2) activities in the supernatant of culture media of mouse spleen cells. TP (50 micrograms/ml) enhanced the lymphocyte proliferation induced by Con A and increased the PFC response to SRBC by 47.1% in 14-month-old mice.     

Cadmium toxicity in kidney cells. Resistance induced by short term pretreatment in vitro and in vivo

Epithelial cells from the kidney were freshly isolated from rats pretreated by daily subcutaneous doses of CdCl2 in vivo (0.5-2 mg Cd/kg X 5). Such cells were incubated in vitro in media with different concentrations of cadmium chloride (0-200 micrograms Cd/ml). There was no inhibition of cell growth in such cells. However, in cells isolated from non-treated rats, in vitro exposure to the same concentrations of CdCl2 caused a dose dependent decrease in viability. When cells, isolated from non-treated rats were pretreated in vitro with CdCl2 (10 micrograms/ml) and subsequently exposed to cadmium chloride (0-200 micrograms/ml), a protective effect was observed, which was similar to the one observed in cells isolated from animals pretreated with CdCl2. The concentration of metallothionein in the cells treated with cadmium was increased. A lower uptake of cadmium chloride, in vitro has been observed in kidney cells pretreated in vivo or in vitro compared to nonpretreated cells. Subcellular distribution studies indicate that Cd-distribution was similar in pretreated and non-pretreated cells, but concentrations were generally lower in the pretreated cells. The decreased uptake of Cd by pretreated kidney cells is a sign of Cd-interference with cellular function. These changes are suggested as a contributing mechanism to the prevention of acute toxic effects of cadmium on the kidney.