title: Silencing of Bmi-1 gene by RNA interference enhances sensitivity to doxorubicin in breast cancer cells.
abstract: The oncogene Bmi-1 is highly up-regulated in breast carcinoma and is found to be efficient in preventing apoptosis of the cancer cells. Doxorubicin is an important chemotherapeutic agent against breast carcinoma. However, the effective therapeutic response to doxorubicin is often associated with severe toxicity. The present study is targetted at developing a strategy to increase doxorubicin sensitivity to lower doses without compromising its efficacy. A stable cell line with a persistent silencing of Bmi-1 was established. MTT assay was performed to evaluate 50% inhibitory concentration (IC50) values of doxorubicin. Apoptosis was detected by FCM and the expression of related genes [phosphor-Akt (pAkt), totle-Akt (tAkt), Bcl-2 and Bax] was studied by Western blot. In vivo, the sensitivity of the tumor tissues against doxorubicin was evaluated by transplanted MCF-7 nude mice model and the apoptosis of tissue cells was detected by TUNEL assay. The expression of pAkt and Bcl-2 was down-regulated, whereas Bax was up-regulated in Bmi-1 silencing cells. The results obtained indicated that silencing of Bmi-1 can render MCF-7 cells more sensitive to doxorubicin which induced a significantly higher percentage of apoptosis cells in vitro and in vivo. All together these results clearly demonstrate that Bmi-1 siliencing combined treatment of doxorubicin might be a new strategy for biological treatment on breast cancer.
authors.affiliation: Department of Physiology, Chongqing Medical University, Chongqing 400016, PR China.
authors.forename: Xiangmei
authors.initials: X
authors.lastname: Wu
authors.forename: Xing
authors.initials: X
authors.lastname: Liu
authors.forename: Joyeeta
authors.initials: J
authors.lastname: Sengupta
authors.forename: Youquan
authors.initials: Y
authors.lastname: Bu
authors.forename: Faping
authors.initials: F
authors.lastname: Yi
authors.forename: Changdong
authors.initials: C
authors.lastname: Wang
authors.forename: Yanyan
authors.initials: Y
authors.lastname: Shi
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhu
authors.forename: Qingfang
authors.initials: Q
authors.lastname: Jiao
authors.forename: Fangzhou
authors.initials: F
authors.lastname: Song
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000235:genetics / Q000628:therapy*; D002277:Carcinoma / Q000235:genetics / Q000628:therapy*; D045744:Cell Line, Tumor; D003131:Combined Modality Therapy; D004317:Doxorubicin / Q000627:therapeutic use*; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D005260:Female; D020868:Gene Silencing / Q000502:physiology; D015316:Genetic Therapy; D006801:Humans; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000235:genetics*; D063150:Polycomb Repressive Complex 1; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors / Q000235:genetics*; D034622:RNA Interference / Q000502:physiology; D034741:RNA, Small Interfering / Q000494:pharmacology; D012097:Repressor Proteins / Q000037:antagonists & inhibitors / Q000235:genetics*; D023041:Xenograft Model Antitumor Assays
chemical_list: C069077:BMI1 protein, human; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D034741:RNA, Small Interfering; D012097:Repressor Proteins; D004317:Doxorubicin; D063150:Polycomb Repressive Complex 1