Rationale : Tumor metastasis is the main cause for cancer-related death. However, the driving molecules of metastasis remain largely unknown. Here, we aim to identify long non-coding RNAs (lncRNAs) critical for human hepatocellular carcinoma (HCC) metastasis. Methods : Microarrays were used to screen a comprehensive set of lncRNAs with differential expression profiles in sulfatide-treated cells. Mass spectrometry, protein arrays, and RNA pull-down experiments were used to identify proteins that interacted with lncRNA. Epigenetic analysis was used to study lncRNA-mediated regulation mechanisms. Results : We identified lncRNA AY927503 (AY) as a metastasis-associated molecule that was highly expressed in human hepatocellular carcinoma (HCC) and correlated with metastatic events and poor prognosis in patients with HCC. AY promoted HCC cell migration, stemness, 5-fluorouracil resistance, and metastasis in mice. However, knockdown of integrin αV (ITGAV) abolished AY-stimulated migration, cell viability in HCC cells or tube formation. AY strongly promoted ITGAV transcription and αVβ3 expression by interacting with the ITGAV promoter specifically and stimulating its activity. AY was identified to interact with histone 1FX (H1FX), but deletion of the central domain of AY (AY∆371-522) abolished H1FX binding and ITGAV promoter stimulation. AY significantly enriched H3K4Me3 and acH3K9/14 but reduced H3K27Me3 and H1FX occupancy on the ITGAV promoter, which remodeled chromatin structures for RNA polymerase II recruitment. Knockdown of H1FX abrogated ITGAV transcription stimulated by AY. Conclusions : Our findings suggested that lncRNA AY promoted HCC metastasis via induction of chromatin modification for ITGAV transcription as a pioneer factor and was a potential molecular signature for metastasis or poor prognosis in patients with HCC.

Background The therapeutic value of targeted therapies in patients with lung cancer is reduced when tumours acquire secondary resistance after an initial period of successful treatment. However, the molecular events behind the resistance to targeted therapies in lung cancer remain largely unknown. Aims To discover the important role and mechanism of lncRNA BC in promoting tumor metastasis and influencing clinical prognosis of LUAD. Materials & Methods: Microarrays were used to screen a comprehensive set of lncRNAs with differential expression profiles in lung cancer cells. The functional role and mechanism of lncRNA were further investigated by gain‐ and loss‐of‐function assays. RNA pull‐down, protein assays, and mass spectrometry were used to identify proteins that interacted with lncRNA. TaqMan PCR was used to measure lncRNA in lung adenocarcinoma and adjacent nontumor tissues from 428 patients. The clinical significance of lncRNA identified was statistically confirmed in this cohort of patients. Results In this study, we show that the long non‐coding RNA BC009639 (BC) is involved in acquired resistance to EGFR‐targeted therapies. Among the 235 long non‐coding RNAs that were differentially expressed in lung cancer cell lines, with different metastatic potentials, BC promoted growth, invasion, metastasis, and resistance to EGFR‐tyrosine kinase inhibitors (EGFR‐TKIs), both in vitro and in vivo. BC was highly expressed in 428 patients with lung adenocarcinoma (LUAD) and high BC expression correlated with reduced efficacy of EGFR‐TKI therapy. To uncover the molecular mechanism of BC‐mediated EGFR‐TKI resistance in lung cancer, we screened and identified nucleolin and hnRNPK that interact with BC. BC formed the splicing complex with nucleolin and hnRNPK to facilitate the production of a non‐protein‐coding inositol monophosphatase domain containing 1 (IMPAD1) splice variant, instead of the protein‐coding variant. The BC‐mediated alternative splicing (AS) of IMPAD1 resulted in the induction of the epithelial–mesenchymal transition and resistance to EGFR‐TKI in lung cancer. High BC expression correlated with clinical progress and poor survival among 402 patients with LUAD. Disscussion Through alternative splicing, BC boosted the non‐coding IMPAD1‐203 transcript variant while suppressing the IMPAD1‐201 variant. In order to control the processing of pre‐mRNA, BC not only attracted RNA binding proteins (NCL, IGF2BP1) or splicing factors (hnRNPK), but also controlled the formation of the splicing‐regulator complex by creating RNA‐RNA‐duplexes. Conclusion Our results reveal an important role for BC in mediating resistance to EGFR‐targeted therapy in LUAD through IMPAD1 AS and in implication for the targeted therapy resistance.

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Background: Long noncoding RNA (lncRNA) is often abnormally expressed in tumors especially hepatocellular carcinoma (HCC) and involved in tumor progression. However, the dysregulation of lncRNA expression in tumors is poorly understood. Methods: The expression of lncRNA was determined and screened by microarray, RT-PCR, qPCR and in situ hybridization in HCC cells. Multiple component transcription analysis, dual-luciferase reporter assays and chromatin immunoprecipitation were performed to investigate transcriptional regulation of the lncRNA expression. Co-immunoprecipitation, point mutation and western blots were carried out for the analysis of acetylation regulation.Results: Here, we showed that lncRNA AY927503 (lncAY) was regulated in HCC cells by sulfatide-mediated transcriptional axis. Sulfatide significantly strengthened lncAY expression and promoted HCC cell migration, proliferation or angiogenesis, whereas cerebroside sulfotransferase silence reduced lncAY expression and drastically hindered HCC cell proliferation, migration or angiogenesis. Interestingly, sulfatide significantly enhanced the activity of reporter carrying lncAY gene promoter. Myb and MEF2C were then identified as the transcription factors responsive to sulfatide and responsible for the stimulation of lncAY promoter activity and lncAY transcription. Both Myb and MEF2C enrichment on lncAY promoter was further confirmed in HCC cells, and their occupancy on lncAY promoter was enhanced by sulfatide for Myb or MEF2C was acetylated. However, Myb mutation of K456/503A prevented Myb from being acetylated under the induction by sulfatide, and the mutant Myb K456/503A was unable to occupy lncAY promoter and enhance lncAY transcription. Myb or MEF2C was complexed with SIN3B or p300. In the presence of sulfatide, HDAC2 dissociation from SIN3B complex was observed. Conclusion: These results uncovered the sulfatide/Myb/MEF2C/lncAY axis in HCC, which controls HCC cell proliferation, and provided an insight into the mechanisms of lncAY dysregulation.

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