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BackgroundLiver tumor initiating cells (TICs) have self-renewal and differentiation properties, accounting for tumor initiation, metastasis and drug resistance. Long noncoding RNAs are involved in many physiological and pathological processes, including tumorigenesis. DNA copy number alterations (CNA) participate in tumor formation and progression, while the CNA of lncRNAs and their roles are largely unknown.MethodsLncRNA CNA was determined by microarray analyses, realtime PCR and DNA FISH. Liver TICs were enriched by surface marker CD133 and oncosphere formation. TIC self-renewal was analyzed by oncosphere formation, tumor initiation and propagation. CRISPRi and ASO were used for lncRNA loss of function. RNA pulldown, western blot and double FISH were used to identify the interaction between lncRNA and CTNNBIP1.ResultsUsing transcriptome microarray analysis, we identified a frequently amplified long noncoding RNA in liver cancer termed linc00210, which was highly expressed in liver cancer and liver TICs. Linc00210 copy number gain is associated with its high expression in liver cancer and liver TICs. Linc00210 promoted self-renewal and tumor initiating capacity of liver TICs through Wnt/β-catenin signaling. Linc00210 interacted with CTNNBIP1 and blocked its inhibitory role in Wnt/β-catenin activation. Linc00210 silencing cells showed enhanced interaction of β-catenin and CTNNBIP1, and impaired interaction of β-catenin and TCF/LEF components. We also confirmed linc00210 copy number gain using primary hepatocellular carcinoma (HCC) samples, and found the correlation between linc00210 CNA and Wnt/β-catenin activation. Of interest, linc00210, CTNNBIP1 and Wnt/β-catenin signaling targeting can efficiently inhibit tumor growth and progression, and liver TIC propagation.ConclusionWith copy-number gain in liver TICs, linc00210 is highly expressed along with liver tumorigenesis. Linc00210 drives the self-renewal and propagation of liver TICs through activating Wnt/β-catenin signaling. Linc00210 interacts with CTNNBIP1 and blocks the combination between CTNNBIP1 and β-catenin, driving the activation of Wnt/β-catenin signaling. Linc00210-CTNNBIP1-Wnt/β-catenin axis can be targeted for liver TIC elimination.

Heterozygosity for the Pax6 allele is associated with impaired glucose tolerance in humans. With a Pax6 mutant mouse model, we found many of the metabolic abnormalities were consistent with the effects of down-regulating the expression of glucagon-like peptide 1 (GLP-1). In addition to impaired glucose tolerance, adult heterozygous mutant mice (Pax6(m/+)) secreted less insulin responding to glucose and arginine administration compared with control mice. Moreover, Pax6(m/+) mice showed increased food intake compared with control mice, although they were resistant to diet-induced fat accumulation. Indeed, levels of circulating GLP-1 and intestinal transcription of Gcg/Proglucagon were dramatically reduced in Pax6(m/+) mice. Mutated Pax6 also failed to activate the Gcg/Proglucagon promoter by in vitro transfection assay. Finally, administering the GLP-1 receptor agonist exendin-4 to Pax6(m/+) mice largely reversed their abnormal food intake, glycemic excursion, and insulin secretion. Our studies suggested that disruption of metabolic homeostasis mainly caused by Pax6 haploinsufficiency was mainly mediated by down-regulation of GLP-1. Administration of exendin-4 may be a useful therapy in humans with a similar mutation.

Whelming evidence has demonstrated that WW domain containing E3 ubiquitin protein ligase 1 (WWP1) participates in a wide variety of biological processes and is tightly related to the initiation and progression of many tumors. Currently, although mounting evidence supports a role of WWP1 in tumor promotion and tumorigenesis, the potential roles of WWP1 and its biological functions in gastric carcinoma are not fully understood. Here, we found that WWP1 messenger RNA (mRNA) and protein were highly expressed in gastric carcinoma tissues and cells. High WWP1 mRNA and protein levels were tightly related to differentiation status, TNM stage, invasive depth, lymph node metastasis, and poor prognosis in gastric carcinoma. Furthermore, WWP1 siRNA significantly decreased WWP1 protein level in MKN-45 and AGS cells; meanwhile, WWP1 depletion markedly inhibited tumor proliferation in vitro and in vivo, arrested cell cycle at G0/G1 phase, and induced cell apoptosis in MKN-45 and AGS cells. Most notably, WWP1 downregulation both inactivated PTEN-Akt signaling pathway in MKN-45 and AGS cells. Taken altogether, our findings suggest that WWP1 acts as an oncogenic factor and should be considered as a novel interfering molecular target for gastric carcinoma.

Liver tumor initiating cells (TICs), a small subset cells in tumor bulk, are responsible for liver tumor initiation, metastasis, and relapse. However, the regulatory mechanism of liver TICs remains largely unknown. Here we found a long noncoding RNA lncAPC, locating near from APC locus, was highly expressed in liver cancer and liver TICs. LncAPC was required for liver TIC self-renewal. Silencing and overexpressing lncAPC showed impaired and enhanced sphere formation capacity of liver TICs, respectively. By recruiting EZH2 to APC promoter, LncAPC inhibits APC transcription and thus drives the activation of Wnt/β-catenin signaling. Attenuate binding between EZH2 and APC promoter was observed upon lncAPC knockdown. What is more, lncAPC-EZH2-APC axis can be targeted to eliminate liver TICs. Altogether, LncAPC promotes liver TIC self-renewal through EZH2-dependent APC transcriptional inhibition.