[miR-202 contributes to sensitizing MM cells to drug significantly via activing JNK/SAPK signaling pathway].

ABSTRACT

Objective: To explore the role of miR-202 in multiple myeloma (MM) cells, and study the regulation of miR-202 on drug sensitivity of MM cells. Methods: miR-202 and BAFF mRNA levels were detected by real-time PCR. U266 cells were transfected with miR-202-mimics, miR-202-inhibitor, siBAFF and their negative controls. After above treatments, protein levels of Bcl-2 family and MAPK signaling pathway were detected by Western blot analysis, and the proliferation and apoptosis ability of MM cells were examined by WST-1, Annexin V-FLUOS assay, respectively. Results: The results showed that the expression of miR-202 in CD138+ MM cells (0.304±0.354) and U266 cells (0.052± 0.009) were lower than in normal controls (3.550 ± 1.126) (P<0.001, P=0.009), whereas BAFF mRNA levels (5.700 ± 0.734, 9.576 ± 2.887) were higher than in normal controls (1.819 ± 0.853) (P<0.001, P= 0.006). The proliferation ability of U266 cells transfected with miR-202 mimics was significantly inhibited than in control group [(56.04±0.021)% vs (18.89±0.32)%, P=0.002]. The result of Western blot showed that the expression of Bcl-2 decreased by about 24%, and the expression of Bax increased by about 124% in cells transfected with miR-202 mimics. The apoptosis rate in cells transfected with miR-202 mimics was significantly more than in control group [(49.60±4.89)% vs (26.20±1.28)%, P=0.029]. The apoptosis rate in miR-202 mimics combined with Bort group (51.23±5.41)% was higher as compared with Bort treatment alone (31.70±4.40)% or miR-202 mimics control combined with Bort group (27.94±4.04)%, (P=0.047, P= 0.028), whereas the apoptosis rate in miR-202 mimics combined with Thal or Dex had no significant difference compared with miR-202 mimics control [(11.66±1.91)% vs (10.63±1.74)%, P=0.700; (16.35± 1.32)% vs (17.43 ± 1.95)%, P=0.400]. The inhibitory rate of cell growth in miR-202 mimics combined with Bort group was higher as compared with Bort treatment alone [(36.93±5.98)% vs (18.18±4.10)%, P= 0.029]. The expressions of p-JNK protein decreased in U266 cells transfected with miR-202 mimics and treated with Bort. Conclusion: miR-202 mimics combined with Bort could inhibit proliferation and induce apoptosis of U266 cells through negative regulating target gene BAFF, which further inhibited the JNK/SAPK signaling pathway.