Circular RNA (circRNA) possesses great pre-clinical diagnostic and therapeutic potentials in multiple cancers. It has been reported playing roles in multiple malignant behaviors including proliferation, migration, metastasis and chemoresistance. However, the underlying correlation between circRNAs and cancer stem cells (CSCs) has not been reported yet. Methods: circZKSCAN1 level was detected in HCC tissue microarrays to clarify its prognostic values. Gain and loss function experiments were applied to investigate the role of circZKSCAN1 in HCC stemness. Bioinformatic analysis was used to predict the possible downstream RNA binding protein and further RNA immunoprecipitation sequencing was carried out to identify the RBP-regulated genes. Results: The absence of circZKSCAN1 endowed several malignant properties including cancer stemness and tightly correlated with worse overall and recurrence-free survival rate in HCC. Bioinformatics analysis and RNA immunoprecipitation-sequencing (RIP-seq) results revealed that circZKSCAN1 exerted its inhibitive role by competitively binding FMRP, therefore, block the binding between FMRP and β-catenin-binding protein-cell cycle and apoptosis regulator 1 (CCAR1) mRNA, and subsequently restrain the transcriptional activity of Wnt signaling. In addition, RNA-splicing protein Quaking 5 was found downregulated in HCC tissues and responsible for the reduction of circZKSCAN1. Conclusion: Collectively, this study revealed the mechanisms underlying the regulatory role of circZKSCAN1 in HCC CSCs and identified the newly discovered Qki5-circZKSCAN1-FMRP-CCAR1-Wnt signaling axis as a potentially important therapeutic target for HCC treatment.

N6-methyladenosine (m6A) has been reported as an important mechanism of posttranscriptional regulation. Programmed death-ligand 1 (PD-L1) is a primary immune inhibitory molecule expressed on tumor cells that promotes immune evasion. Here we report ALKBH5 as an important m6A demethylase that orchestrates PD-L1 expression in intrahepatic cholangiocarcinoma (ICC). Regulation of PD-L1 expression by ALKBH5 was confirmed in human ICC cell lines. Sequencing of the m6A methylome identified PD-L1 mRNA as a direct target of m6A modification whose levels were regulated by ALKBH5. Furthermore, ALKBH5 and PD-L1 mRNA were shown to interact. ALKBH5 deficiency enriched m6A modification in the 3′UTR region of PD-L1 mRNA, thereby promoting its degradation in a YTHDF2-dependent manner. In vitro and in vivo, tumor-intrinsic ALKBH5 inhibited the expansion and cytotoxicity of T cells by sustaining tumor cell PD-L1 expression. The ALKBH5-PD-L1–regulating axis was further confirmed in human ICC specimens. Single-cell mass cytometry analysis unveiled a complex role of ALKBH5 in the tumor immune microenvironment by promoting the expression of PD-L1 on monocytes/macrophages and decreasing the infiltration of myeloid-derived suppressor-like cells. Analysis of specimens from patients receiving anti-PD1 immunotherapy suggested that tumors with strong nuclear expression patterns of ALKBH5 are more sensitive to anti-PD1 immunotherapy. Collectively, these results describe a new regulatory mechanism of PD-L1 by mRNA epigenetic modification by ALKBH5 and the potential role of ALKBH5 in immunotherapy response, which might provide insights for cancer immunotherapies. Significance: This study identifies PD-L1 mRNA as a target of ALKBH5 and reveals a role for ALKBH5 in regulating the tumor immune microenvironment and immunotherapy efficacy.

Spatial transcriptome technique was applied to decipher the spatial architecture and TME characteristics of liver cancers.

Triple-negative breast cancer (TNBC) is a subtype of breast cancer (BC) with the most aggressive phenotype and poor overall survival. Using bioinformatics tools, we identified LINC00908 encoding a 60–aa polypeptide and differentially expressed in TNBC tissues. We named this endogenously expressed polypeptide ASRPS (a small regulatory peptide of STAT3). ASRPS expression was down-regulated in TNBCs and associated with poor overall survival. We showed that LINC00908 was directly regulated by ERα, which was responsible for the differential down-regulation of LINC00908 in TNBCs. ASRPS directly bound to STAT3 through the coiled coil domain (CCD) and down-regulated STAT3 phosphorylation, which led to reduced expression of VEGF. In human endothelial cells, a mouse xenograft breast cancer model, and a mouse spontaneous BC model, ASRPS expression reduced angiogenesis. In a mouse xenograft breast cancer model, down-regulation of ASRPS promoted tumor growth, and ASRPS acted as an antitumor peptide. We presented strong evidence that LINC00908-encoded polypeptide ASRPS represented a TNBC-specific target for treatment.

Long non-coding RNAs (lncRNA) have been shown to play critical roles in many diseases, including esophageal squamous cell carcinoma (ESCC). Recent studies have reported that some lncRNA encode functional micropeptides. However, the association between ESCC and micropeptides encoded by lncRNA remains largely unknown. In this study, we characterized a Y-linked lncRNA, LINC00278, which was downregulated in male ESCC. LINC00278 encoded a Yin Yang 1 (YY1)-binding micropeptide, designated YY1BM. YY1BM was involved in the ESCC progression and inhibited the interaction between YY1 and androgen receptor (AR), which in turn decreased expression of eEF2K through the AR signaling pathway. Downregulation of YY1BM significantly upregulated eEF2K expression and inhibited apoptosis, thus conferring ESCC cells more adaptive to nutrient deprivation. Cigarette smoking decreased m 6 A modification of LINC00278 and YY1BM translation. In conclusion, these results provide a novel mechanistic link between cigarette smoking and AR signaling in male ESCC progression. SIGNIFICANCEPost-transcriptional modification of a micropeptide-encoding lncRNA is negatively impacted by cigarette smoking, disrupting negative regulation of the AR signaling pathway in male ESCC.

The current study examined the associations between specific Internet activities (online shopping, pornography use, social networking site use, and Internet gaming), life satisfaction, and the mediating effects of loneliness and depression for these associations. Participants were 5,215 students (2,303 male participants, Mage = 16.20 years; ranging in age from 10 to 23 years) from various school types (546 elementary school students, 1710 junior high school students, 688 senior high school students, and 2271 university students) who provided self-report data on demographic variables, online shopping, pornography use, social networking site use, loneliness, depression, and life satisfaction. The results indicated that after controlling for demographic variables (gender and age) (a) loneliness and depression had fully positive mediating effects on the association between social networking site use and life satisfaction; (b) loneliness and depression played fully negative mediating effects on life satisfaction associations with online shopping, pornography use, and Internet gaming. Therefore, loneliness and depression were the underlying mechanisms that caused life satisfaction to be affected by online shopping, pornography use, social networking site use, and Internet gaming.

TGF-b signaling pathway plays a key role in breast cancer metastasis. Recent studies suggest that TGF-b regulates tumor progression and invasion not only via transcriptional regulation, but also via translational regulation. Using both bioinformatics and experimental tools, we identified a micropeptide CIP2A-BP encoded by LINC00665, whose translation was downregulated by TGF-b in breast cancer cell lines. Using TNBC cell lines, we showed that TGF-b-activated Smad signaling pathway induced the expression of translation inhibitory protein 4E-BP1, which inhibited eukaryote translation initiation factor elF4E, leading to reduced translation of CIP2A-BP from LINC00665. CIP2A-BP directly binds tumor oncogene CIP2A to replace PP2A's B56c subunit, thus releasing PP2A activity, which inhibits PI3K/AKT/NFjB pathway, resulting in decreased expression levels of MMP-2, MMP-9, and Snail. Downregulation of CIP2A-BP in TNBC patients was significantly associated with metastasis and poor overall survival. In the MMTV-PyMT model, either introducing CIP2A-BP gene or direct injection of CIP2A-BP micropeptide significantly reduced lung metastases and improved overall survival. In conclusion, we provide evidence that CIP2A-BP is both a prognostic marker and a novel therapeutic target for TNBC.

Background and Aims Heparin‐binding epidermal growth factor (HB‐EGF), a member of the epidermal growth factor family, plays a pivotal role in the progression of several malignancies, but its role and regulatory mechanisms in hepatocellular carcinoma (HCC) remain obscure. Here, we report that transmembrane protease serine 4 (TMPRSS4) significantly enhanced the expression and proteolytic cleavage of HB‐EGF to promote angiogenesis and HCC progression. Approach and Results A mechanistic analysis revealed that TMPRSS4 not only increased the transcriptional and translational levels of HB‐EGF precursor, but also promoted its proteolytic cleavage by enhancing matrix metallopeptidase 9 expression through the EGF receptor/Akt/mammalian target of rapamycin/ hypoxia‐inducible factor 1 α signaling pathway. In addition, HB‐EGF promoted HCC proliferation and invasion by the EGF receptor/phosphoinositide 3‐kinase/Akt signaling pathway. The level of HB‐EGF in clinical samples of serum or HCC tissues from patients with HCC was positively correlated with the expression of TMPRSS4 and the microvessel density, and was identified as a prognostic factor for overall survival and recurrence‐free survival, which suggests that HB‐EGF can serve as a potential therapeutic target for HCC. More importantly, we provide a demonstration that treatment with the HB‐EGF inhibitor cross‐reacting material 197 alone or in combination with sorafenib can significantly suppress angiogenesis and HCC progression. Conclusions HB‐EGF can be regulated by TMPRSS4 to promote HCC proliferation, invasion, and angiogenesis, and the combination of the HB‐EGF inhibitor cross‐reacting material 197 with sorafenib might be used for individualized treatment of HCC.