[Insulin induces anticancer cytotoxicity of 5-Fu to two human colon cancer cell lines].
OBJECTIVE
To explore the possibility of use of insulin as a potentiator of 5-Fu to human colon cancer cell lines HCT-8 and HT-29 and study its mechanism.


METHODS
MTT assay was used to examine the inhibition rate of cell growth after treatment with 5-Fu and insulin. Cell cycle was determined by flow cytometry.


RESULTS
Insulin showed an enhancing effect on the chemotherapeutic response of 5-Fu when insulin was applied at a dose of exceeding 0.8 mU/ml 0 approximately 8 h before 5-Fu. Within the range of from 0.8 mU/ml to 8 mU/ml, a higher concentration of insulin gave a higher proportion of inhibited cells. But when the insulin concentration exceeds 8 mU/ml, the proportion became stable as that of 8 mU/ml. Insulin increased the percentage of S phase cells and decreased the percentage of G(1) phase cells (P < 0.01). The percentage of S phase cells reached a peak when the cells were treated with insulin for 6 hours.


CONCLUSIONS
Insulin can enhance the anticancer toxicity of 5-Fu to human colon cancer cell lines HCT-8 and HT-29 cells. Insulin increases the percentage of S phase cells, which may be one of the main mechanisms of insulin-induced enhancement of anticancer response of cancer cells to 5-Fu chemotherapy.
Ma
Wang
W
Department of Oncology, the First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China.
Wang
Liu-xing
LX
Wang
Rui-lin
RL
Fan
Qing-xia
QX
Lu
Shi-xin
SX
D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D002453:Cell Cycle / Q000187:drug effects*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D003110:Colonic Neoplasms / Q000473:pathology*; D004305:Dose-Response Relationship, Drug; D005472:Fluorouracil / Q000494:pharmacology*; D019073:HT29 Cells; D006801:Humans; D007328:Insulin / Q000008:administration & dosage / Q000494:pharmacology*; D016196:S Phase; D013997:Time Factors
D000964:Antimetabolites, Antineoplastic; D007328:Insulin; D005472:Fluorouracil