[The synergistic inhibitory effect of 5-aza-2-deoxycytidine and Tamoxifen on estrogen receptor alpha negative breast cancer cell lines in vitro].
OBJECTIVE
To observe if ER alpha gene can be induced by 5-aza-CdR in ER alpha negative human breast cancer cell lines (MDA-MB-231 and MDA-MB-435) and the synergistic inhibitory effects of 5-aza-CdR and Tamoxifen on these two cell lines in vitro.


METHODS
The status of 5'CpG island methylation of ER alpha gene in ER alpha negative (MDA-MB-231 and MDA-MB-435) human breast cancer cell lines and 20 cases of breast cancer tissue was studied by MSP, the expression of ER alpha mRNA was inspected by using RT-PCR after these two cell lines were treated with 5-aza-CdR. Cell proliferation was evaluated by MTT assay, distribution of cell cycle and rate of apoptosis were determined by flow cytometry after these two cell lines were treated with 5-aza-CdR or TAM alone, or in combination in vitro.


RESULTS
The 5'CpG island is methylated in the core promotor of ER alpha gene in ER alpha negative (MDA-MB-231 and MDA-MB-435) human breast cancer cell lines and the methylating rate is 25.0%, 66.7%, 83.3%, 100% in 20 cases of breast cancer tissue of stage I, II, III, IV, respectively. The expression of ER alpha mRNA was induced in these two cell lines after treated with 5-aza-CdR, MTT array showed the proliferation activity of these two cell lines was obviously reduced in 5-aza-CdR group and the inhibitory effect on proliferation was enhanced when 5-aza-CdR combined with TAM compared with control group, the induction of apoptosis was 11.20% and 8.71% respectively by 5-aza-CdR, while the rate of apoptosis is 48.8% and 53.1% when these two cells were treated with 5-aza-CdR combined with TAM.


CONCLUSIONS
5-aza-CdR can re-express ER alpha by demethylating and sensitive ER alpha negative human breast cancer cell lines to TAM, 5-aza-CdR and TAM synergistically inhibit proliferation and induce apoptosis in ER alpha negative human breast cancer cell lines, thus offer a new way for the treatment of ER alpha negative breast cancer.
Tang
Bo
B
Department of General Surgery, Southwest Hospital, Third Military Medical University, Chongqing 400038, China.
Peng
Zhi-hong
ZH
Jiang
Jun
J
D000328:Adult; D000368:Aged; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D001374:Azacitidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D045744:Cell Line, Tumor; D000077209:Decitabine; D004357:Drug Synergism; D047628:Estrogen Receptor alpha / Q000096:biosynthesis* / Q000235:genetics; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D008875:Middle Aged; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013629:Tamoxifen / Q000494:pharmacology*
D000964:Antimetabolites, Antineoplastic; D047628:Estrogen Receptor alpha; D012333:RNA, Messenger; D013629:Tamoxifen; D000077209:Decitabine; D001374:Azacitidine