LncRNA LHFPL3-AS1 contributes to tumorigenesis of melanoma stem cells via the miR-181a-5p/BCL2 pathway

Long noncoding RNAs (lncRNAs) are recognized as a new area for cancer therapy. B-cell lymphoma-2 (Bcl-2)-mediated suppression of apoptosis is an important molecular hallmark of cancer. However, the influence of lncRNA on the regulation of oncogenic Bcl-2 in cancer stem cells has not been explored. In this study, our findings revealed that the lncRNA LHFPL3-AS1-long, generated from the polypyrimidine tract binding protein 1 (PTBP1)-mediated splicing of the LHFPL3-AS1 precursor, upregulated BCL2 protein to contribute to tumorigenesis of melanoma stem cells. The in vitro and in vivo results showed that LHFPL3-AS1-long directly interacted with miR-181a-5p to inhibit the mRNA degradation of Bcl-2 (the target of miR-181), thus suppressing apoptosis of melanoma stem cells. The splicing factor PTBP1 regulated the alternative splicing of LHFPL3-AS1 transcript by preferentially binding to the motifs located in exon3 of LHFPL3-AS1 precursor, leading to the biogenesis of LHFPL3-AS1-long in melanoma stem cells. In patients with melanoma, the expressions of PTBP1 and LHFPL3-AS1 were significantly upregulated compared with the healthy donors. Therefore, our study revealed a mechanistic crosstalk among an onco-splicing factor, lncRNA and tumorigenesis of melanoma stem cells, enabling PTBP1 and LHFPL3-AS1 to serve as the attractive therapeutic targets for melanoma.