[Relationship between multidrug resistance in human colon carcinoma LoVo/Adr cell line and intracellular calcium ion concentration].
OBJECTIVE
Based on the findings that calcium content increased in multidrug resistant (MDR) cells and that the resistance could be reversed by the calcium channel blocker verapamil, it has been speculated that Ca2+ may have role in drug resistance. This study was designed to investigate the relationship between multidrug resistance in human colon carcinoma LoVo/Adr cells and the level of cytoplasmic Ca2+.


METHODS
Fluo-3/AM was used to label Ca2+ in the cytoplasm and confocal microscope was used to observe the changes of Ca2+ concentration. The reverse effect of verapamil was determined by MTT method. The content of intracellular adriamycin(ADR) was determined by flow cytometry.


RESULTS
Fluo-3/AM fluorescent intensities of LoVo and LoVo/Adr cells were 850.45 and 1,495.88, respectively. After treatment with verapamil, Fluo-3/AM fluorescent intensities of LoVo and LoVo/Adr cells were 813.25 and 1,284.14, respectively. The level of Ca2+ in the cytoplasm of LoVo/Adr cells was significantly higher than that in LoVo cells, and was not significantly changed by verapamil. The concentration of ADR was increased by verapamil in LoVo/Adr cells. The potentiation folds of adriamycin and vincristine by verapamil in LoVo/Adr cells were 8.85 and 5.31, respectively.


CONCLUSIONS
The increasement of cytoplasmic calcium content might be a characteristic phenotype of MDR LoVo/Adr cells. However, there was no direct relationship between multidrug resistance and cytoplasmic Ca2+ concentration.
Ma
Qiang
Q
Department of Gastroenterology, Nafang Hospital, First Military Medical University, Guangzhou 510515, P. R. China.
Zhang
Zhen-shu
ZS
Zhang
Ya-li
YL
Lai
Zhuo-sheng
ZS
D002118:Calcium / Q000378:metabolism*; D003110:Colonic Neoplasms / Q000378:metabolism* / Q000473:pathology; D004317:Doxorubicin / Q000378:metabolism / Q000494:pharmacology; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D006801:Humans; D008856:Microscopy, Fluorescence; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000378:metabolism; D014700:Verapamil / Q000494:pharmacology; D014750:Vincristine / Q000378:metabolism / Q000494:pharmacology
D014750:Vincristine; D004317:Doxorubicin; D014700:Verapamil; D002118:Calcium