CHML suppresses cell growth and induces apoptosis in multiple human tumor lines

In the present study, we have investigated the effect of cytotropic heterog eneous molecular lipid (CHML), a new anticancer agent, on growth suppressio n in a variety of human tumor cell lines. At a non-toxic concentration (a r ange from 25 mu g/ml to too mu g/ml) CHML has shown to strongly inhibit tum or cell growth by using a typical colony survival assay. At a treatment of concentration of 50 mu g/ml for 6 hours, CHML is able to suppress 50% of th e tumor. cell colony formation. At a concentration of 100 mu g/ml (the ther apeutic dosage in the clinical trial), more than 90% of the cells were kill ed in human breast carcinoma MCF-7, colorectal carcinoma RKO, kidney carcin oma G410, lung carcinoma and human myeloid leukemia ML-1 lines. In contrast , growth suppression of non-cancerous human skin fibroblasts by CHML was ob served much less than that seen in firmer lines. These results indicate tha t CHML is an efficient inhibiting agent in tumor cell growth and is able to generate greater suppression in tumor cells than in noncancerous cells. Wi th the use of DNA fragmentation assay, CHML was found to induce apoptosis i n MCF-7, ML-I, H1299 and RKO lines after treatment at a concentration of 75 mu g/ml for 8 hours. Following the CHML treatment, the tumor suppressor p5 3 protein elevated in RKO cells at 2 h posttreatment. The induction of p53 reached a peak at 4 hi. and returned to normal level 16 hr later Consistent with this result Bar, which is regulated by p53 and is able to promote apo ptosis, was also found to increase in a same kinetic manner as p53. These r esults suggest that the p53-pathway is activated by CHML and the activation of p53 may contribute to CHML-induced apoptosis in some tumor cells, such as MCF-7, RKO and ML-I. Considering that CHML is able to induce apoptosis i n H1299 cells, which are of p53-negative statics, it is speculated that CHM L induces programmed cell death through both the p53-dependent and independ ent pathways.