Cytotoxic and anticancer effects of the triorganotin compound [(C6H5)3Sn(cmbzt)]: An in vitro, ex vivo and in vivo study

Since the initial success of cisplatin, metal complexes and organometallic compounds have been gaining growing interest in cancer therapy. It is well known that organotin(IV) compounds display strong biological activity. The triorganotin compound [(C6H5)3Sn(cmbzt)] (cmbzt = 5-chloro-2-mercaptobenzothiazole) (SnCMB), was tested for its antiproliferative and antitumour activities. Two sets of experimental procedures were followed: (1) In vitro and ex vivo procedures included the study of the cytotoxic activity of the complex against leiomyosarcoma cells (LMS) and on a normal human fibroblast line (MRC5) by the MTT assay (cell proliferation), colony formation efficiency and flow cytometric analysis with Annexin V-FITC. The anticoagulation properties of the complex were also studied. (2) In vivo procedures included acute toxicity studies and finally administration of the complex to tumour bearing Wistar rats. The results showed that the complex exhibited potent cytotoxic activity (LMS IC50 = 155 nM) and induced significant apoptosis against LMS cells. Acute toxicity studies on Wistar rats presented kidney and liver toxicity at a single dose of 40 mg/kg body wt. Furthermore, antitumour activity studies on sarcoma bearing Wistar rats revealed that SnCMB complex, administrated in two different therapeutic schemes (treated with 4 × 2 mg/kg body wt every 5 days and 3 × 2.67 mg/kg body wt every 10 days of SnCMB complex), prolonged mean survival time (by 50% and 70% respectively), but failed to decrease the mean tumour growth rate (MTGR) compared to the control group (p < 0.01). In conclusion, the organic complex SnCMB possess potent cytotoxic and antimetastatic effects, and low toxicity introducing it as possible successor of organometallic compounds used nowadays in chemotherapy.