N-methylformamide effects on cell proliferation and antigenic pattern in HT-29 colon carcinoma cell line

N-methylformamide and 9-hydroxystearic acid: two anti-proliferative and differentiating agents with different modes of action in colon cancer cells

N-methylformamide (NMF) is an anti-proliferative, differentiating agent studied in several cell lines as well as in preclinical and clinical trials, whose mechanisms of action are still unclear. 9-Hydroxystearic acid (9-HSA) is an endogenous product of lipid peroxidation recently identified as a new histone deacetylase 1 inhibitor. Both agents show the same anti-proliferative effects by arresting colon cancer cell growth in G0/G1. We addressed two questions. (i) Do they act by regulating G0/G1 checkpoint proteins? (ii) Does 9-HSA have differentiating effects comparable to those of NMF? The effects of NMF and 9-HSA on growth, differentiation and invasiveness of HT29, a colon cancer cell line, have been compared by using immunoprecipitation analysis, confocal microscopy, enzyme assays and invasiveness tests. The results show that the G1 arrest caused by NMF is a cell cycle exit due to p27 induction, whereas 9-HSA has no effect on the induction of this inhibitor. Evidence is presented that the arrest in early G0/G1 induced by 9-HSA is associated with the conversion of HT29 characteristics to those of a more benign phenotype, whereas the arrest in the late G1 in response to NMF is not followed by a decrease in tumorigenicity. The failure of NMF in cancer therapy indicates that both anti-proliferative and differentiating characteristics are required for an anti-tumoral agent to be effective.

N-methylformamide as a potential therapeutic approach in colon cancer

PURPOSE

The effect of N-methylformamide, used in combination with the antineoplastic drugs adriamycin and cisplatin, on the cell survival of a colon carcinoma cell line (HT-29) was investigated. To better understand the mechanism involved in N-methylformamide-mediated chemosensitization, we evaluated the N-methylformamide effect on cell volume and surface expression of some integrins molecules (VLA2, VLA5, and VLA6) of the HT-29 cell line.

METHODS

The cell survival was evaluated by clonogenic assay; integrins surface expression was analyzed by means of flow cytometry; cell volumes were determined using a Coulter Channalyzer.

RESULTS

A Noncytotoxic dose of N-methylformamide (170 mM) sensitizes the HT-29 cell line to the lethal activity of both adriamycin and cisplatin. The analysis of cell volume showed that N-methylformamide exposure induces an increase in cell volume. Flow cytometric analysis of VLA2, VLA5, and VLA6 receptors showed that N-methylformamide increases the expression of the three integrins by 30 to 40 percent.

CONCLUSION

The plasma membrane could constitute one of the N-methylformamide targets and might be involved in the differentiation and chemosensitizing effects caused by this agent. Moreover, N-methylformamide could improve colon cancer treatment when used in combination with antineoplastic drugs.