M-CSF on hypoxia-inducible factor-1α (HIF-1α)/BCL2/adeno- virus E1B 19 kDa-interacting protein 3 (BNIP3)/Apoptosis Regulator BAX signalling in human breast cancer MCF-7 cells were investigated. Western blotting revealed that the expression of HIF-1α, BNIP3, Bax, caspase-3 and caspase-9 was lower in 

Macrophage colony-stimulating factor (M-CSF), a tumour marker, is related to tumour cell anti-apoptosis and drug resistance. However, the role of M-CSF in MCF-7 cells is unknown. In the present study, the effect and mechanism of M-CSF on hypoxia-inducible factor-1α (HIF-1α)/BCL2/adenovirus E1B 19 kDa-interacting protein 3 (BNIP3)/Apoptosis Regulator BAX signalling in human breast cancer MCF-7 cells were investigated. Western blotting revealed that the expression of HIF-1α, BNIP3, Bax, caspase-3 and caspase-9 was lower in MCF-7-M cells compared to MCF-7 and MCF-7-C cells treated with adriamycin (ADM). Immunoprecipitation combined with western blotting was used to detect the interaction between Bcl-2 and BNIP3 or Bax protein. MCF-7-M cells had a higher amount of Bax binding to Bcl-2 compared to MCF-7 cells or MCF-7-C cells, while the amount of BNIP3 binding to Bcl-2 was decreased in MCF-7-M cells. Hoechst 33342 staining and flow cytometry were utilized to evaluate the effect of M‐CSF on apoptosis in MCF-7 cells treated with ADM. Compared to ADM-treated MCF-7 cells, the apoptotic rate of MCF-7-M cells was significantly decreased. These effects were dependent on the concentration of ADM. In conclusion, cytoplasmic M-CSF suppressed apoptosis by inhibiting the HIF-1α/BNIP3/Bax signalling pathway, which potentiated the dissociation of Bcl-2 from Bcl-2-BNIP3 compounds and the formation of Bcl-2-Bax compounds. Introduction Macrophage colony-stimulating factor (M-CSF), also known as colony-stimulating factor-1 (CSF-1), promotes monocyte and macrophage cell growth, proliferation, and differentiation as well as maintenance of the biological functions of monocytes and macrophages. Notably, M-CSF is also expressed in many tumour tissues and cancer cells. The expression of M-CSF is markedly enhanced in various cancers (1-3). Increased nuclear expression of M-CSF was revealed to be correlated with poor prognosis and the metastatic potential of breast cancer cells (4). Aharinejad et al found that the high expression of cytoplasmic M-CSF in MDA-MB-231 breast cancer cells contributes to the invasion and metastasis of tumours in a mouse model (2). Similarly, M-CSF was revealed to play an important role in the resistance of 5-FU in U87MG glioblastoma (5). In addition, an M-CSF antibody was revealed to reverse the chemoresistance of MCF-7 cells (6). In our previous study, it was revealed that M-CSF induced drug and apoptosis resistance in MCF-7 cells. Therefore, M-CSF is a tumour marker since it is related to anti-apoptosis and drug resistance in tumour cells. Apoptosis is a common form of programmed cell death, and its deregulation has been associated with tumour initiation, progression, and metastasis in various cancers including breast cancer (7). HIF-1 has been demonstrated to be involved in glycolysis, angiogenesis and migration, and to regulate invasion factors that are important for tumour progression and metastasis (8). HIF-1 activity depends on the expression level of HIF-1α. HIF-1α expression is maintained at low levels under normoxic conditions, however it is significantly induced by hypoxia (9). HIF-1α induces various transcriptional programs, some of which include pluripotency factors in hypoxic conditions (10). A recent study revealed that HIF-1α regulated anti-apoptotic genes, which ultimately led to increased tumour growth and drug resistance (11). Murine double minute 2 (MDM2), is an oncogene that is upstream of HIF-1α and regulates the expression of HIF-1α (12,13). M-CSF was revealed to directly decrease the expression of MDM2, Cytoplasmic M‐CSF facilitates apoptosis resistance by inhibiting the HIF‐1α/BNIP3/Bax signalling pathway in MCF‐7 cells MENGXIA ZHANG1,3*, QI LIU3*, LIJUN LI4*, JING NING5, JIAN TU4, XIAOYONG LEI4, ZHONGCHENG MO3 and SHENGSONG TANG2,4,5 1Department of Histology and Embryology, Hunan University of Chinese Medicine, Changsha, Hunan 410208; 2Hunan Province Key Laboratory for Antibody-based Drug and Intelligent Delivery System, Hunan University of Medicine, Huaihua, Hunan 418000; 3Clinical Anatomy and Reproductive Medicine Application Institute, Department of Histology and Embryology; 4Insitute of Pharmacy and Pharmacology, University of South China, Hengyang, Hunan 421001; 5Department of Pharmacology, Hunan University of Medicine, Huaihua, Hunan 418000, P.R. China Received April 3, 2018; Accepted November 28, 2018 DOI: 10.3892/or.2018. 6949 Correspondence to: Professor Shengsong Tang, Hunan Province Key Laboratory for Antibody-based Drug and Intelligent Delivery System, Hunan University of Medicine, Huaihua, Hunan 418000,