Background
N6-methyladenosine (m6A)-mediated epitranscriptomic pathway has been shown to contribute to chemoresistance and radioresistance. Our previous work confirmed the defense of lycorine against tamoxifen resistance of breast cancer (BC) through targeting HOXD antisense growth-associated long non-coding RNA (HAGLR). Whereas, the precise regulation among them remains to be elucidated. The
Conclusions
Our results demonstrated that lycorine inhibits tamoxifen-resistant BC by repressing IGF2BP2-mediated m6A methylation of HAGLR.
Methods
m6A status was detected via methylated RNA immunoprecipitation-quantitative polymerase chain reaction (MeRIP-qPCR). Relative expression of HAGLR and IGF2BP2 were tested by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot analysis, respectively. Cell viability, proliferation and apoptosis were estimated via Cell Counting Kit-8 (CCK-8), colony formation and flow cytometer analysis. Interplay among IGF2BP2 and HAGLR was tested by RNA immunoprecipitation (RIP) assay. IC50 value of BC cells to tamoxifen was determined by 2,5-diphenyl-2H-tetrazolium bromide (MTT) assay.
Results
Total m6A level in tamoxifen-resistant BC cells (TAMR/MCF-7 and TAMR/T47D) was elevated relative to corresponding parental cells and normal mammary epithelial cell line, MCF10A, either with the presence of m6A modifications within HAGLR sequence. Moreover, IGF2BP2-mediated m6A methylation drove the upregulation and stability of HAGLR in TAMR BC cells. IGF2BP2 served as a key downstream target mediating the anti-tumors of lycorine on TAMR BC. Knockdown of IGF2BP2 or HAGLR could reduce the IC50 value of TAMR/MCF-7 and TAMR/T47D cells to tamoxifen. Conclusions: Our results demonstrated that lycorine inhibits tamoxifen-resistant BC by repressing IGF2BP2-mediated m6A methylation of HAGLR.