miR-148b reverses cisplatin-resistance in non-small cell cancer cells via negatively regulating DNA (cytosine-5)-methyltransferase 1(DNMT1) expression.
BACKGROUND
The emergence of drug resistance in cancer patients limits the success rate of clinical chemotherapy. MicroRNAs (miRNAs) may play a role in chemoresistance and may be involved in modulating of some drug resistance-related pathways in cancer cells. In this study, the involvement of microRNA-148b (miR-148b) and its roles in the development of chemoresistance in lung cancer are determined.


METHODS
This study was performed in two lung cancer cell lines (A549 and SPC-A1). The levels of miR-148b and DNMT1 mRNA expression were determined by using Quantitative Real-Time PCR. Proteins of DNMTs are represented by western blot assay. Cell viability was assessed by MTT assay. Cell apoptosis was evaluated using flow cytometry.


RESULTS
The data showed a down-regulated of miR-148b expression and evaluated methyltransferases (DNMTs) expression in cisplatin-resisted human non-small cell lung cancer (NSCLC) cell line-A549/DDP and SPC-A1/DDP compared with their parental A549 and SPC-A1 cell line. In transfection experiments, miR-148b mimics reduced the DNMT1 expression, as well as enhanced the sensitivity of cells to cisplatin and cisplatin-induced apoptosis in A549/DDP or SPC-A1/DDP cells. While miR-148b inhibitor increased DNMT1 expression, as well as attenuated the sensitivity of cells to cisplatin in A549 and SPC-A1 cells. miR-148b was showed to exert negative effect on DNMT1 expression by targeting its 3'UTR in A549/DDP and A549 cells. Importantly, silenced DNMT1 increases cisplatin sensitivity of A549/DDP cells and over-expressed DNMT1 reverses pro-apoptosis effect of miR-148b mimic.


CONCLUSIONS
miR-148b reverses cisplatin-resistance in non-small cell cancer cells via negatively regulating DNMT1 expression.
Molecular Oncology Department of Cancer Research institution, The First Hospital of China Medical University, 155 Nanjing North Street, He-ping District of Shenyang City, Liaoning Province, 110001, China. Chengguang_S@163.com.
Chengguang
C
Sui
Molecular Oncology Department of Cancer Research institution, The First Hospital of China Medical University, 155 Nanjing North Street, He-ping District of Shenyang City, Liaoning Province, 110001, China. Fand_Meng@163.com.
Fandong
F
Meng
Molecular Oncology Department of Cancer Research institution, The First Hospital of China Medical University, 155 Nanjing North Street, He-ping District of Shenyang City, Liaoning Province, 110001, China. Li_Yan89@163.com.
Yan
Y
Li
Molecular Oncology Department of Cancer Research institution, The First Hospital of China Medical University, 155 Nanjing North Street, He-ping District of Shenyang City, Liaoning Province, 110001, China. Youhong_J@163.com.
Youhong
Y
Jiang
D000970:Antineoplastic Agents / Q000627:therapeutic use*; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000627:therapeutic use*; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000235:genetics*; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics; D035683:MicroRNAs / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction
D000970:Antineoplastic Agents; C550570:MIRN148 microRNA, human; D035683:MicroRNAs; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; C000619380:DNMT1 protein, human; D002945:Cisplatin