Rhomboid proteins perform a wide range of important functions in a variety of organisms. Recent studies have revealed that rhomboid proteins are involved in human cancer progression; however, the underlying molecular mechanism remains largely unclear. Here we show that RHBDD1, a rhomboid intramembrane serine protease, is highly expressed and closely associated with survival in patients with colorectal cancer. We observe that inactivation of RHBDD1 decreases tumor cell growth. Further studies show that RHBDD1 interacts with proTGFα and induces the ADAM-independent cleavage and secretion of proTGFα. The secreted TGFα further triggers the activation of the EGFR/Raf/MEK/ERK signalling pathway. Finally, the positive correlation of RHBDD1 expression with the EGFR/Raf/MEK/ERK signalling pathway is further corroborated in a murine model of colitis-associated colorectal cancer. These findings provide evidence of a growth-promoting role for RHBDD1 in colorectal cancer and may aid the development of tumor biomarkers or antitumor therapeutics.

40–50% of colorectal cancer (CRC) patients develop metastatic disease; the presence of metastasis hinders the effective treatment of cancer through surgery, chemotherapy and radiotherapy, which makes 5-year survival rate extremely low; therefore, studying CRC metastasis is crucial for disease therapy. In the present study, we investigated the role of rhomboid domain containing 1 (RHBDD1) in tumor metastasis of CRC. The expression of RHBDD1 was analyzed in 539 colorectal tumor tissues for its correlation with lymphatic metastasis and distal metastasis. Transwell assay in vitro and pleural metastasis analysis in vivo were performed to determine the functions of RHBDD1 during CRC cells metastasis. RNA-seq analysis, TOP/FOP flash reporter assay, western blot and transwell assay were performed to investigate the underlying mechanism for the function of RHBDD1 on Wnt signaling pathway. Bioinformatics analysis was conducted to investigate epithelial-mesenchymal transition (EMT) and stemness in HCT-116 cells. Tissue microarray analysis, Q-PCR and western blot were performed to determine the correlation of RHBDD1 and Zinc Finger E-Box Binding Homeobox 1 (ZEB1). In this study, we found that RHBDD1 expression was positively correlated with lymphatic metastasis and distal metastasis in 539 colorectal tumor tissues. RHBDD1 expression can promote CRC cells metastasis in vitro and in vivo. RNA-Seq analysis showed that the Wnt signaling pathway played a key role in this metastatic regulation. RHBDD1 mainly regulated ser552 and ser675 phosphorylation of β-catenin to activate the Wnt signaling pathway. Rescuing ser552 and ser675 phosphorylation of β-catenin resulted in the recovery of signaling pathway activity, migration, and invasion in CRC cells. RHBDD1 promoted EMT and a stem-like phenotype of CRC cells. RHBDD1 regulated the Wnt/β-catenin target gene ZEB1, a potent EMT activator, at the RNA and protein levels. Clinically, RHBDD1 expression was positively correlated with ZEB1 at the protein level in 71 colon tumor tissues. Our findings therefore indicated that RHBDD1 can promote CRC metastasis through the Wnt signaling pathway and ZEB1. RHBDD1 may become a new therapeutic target or clinical biomarker for metastatic CRC.

TP53 is one of the most frequently mutated genes among all cancer types, and TP53 mutants occur more than 60% in colorectal cancer (CRC). Among all mutants, there are three hot spots, including p53-R175H, p53-R248W and p53-R273H. Emerging evidence attributes cancer carcinogenesis to cancer stem cells (CSCs). Long noncoding RNAs (lncRNAs) play crucial roles in maintaining the stemness of CSCs. However, it is unknown if mutant p53-regulated lncRNAs are implicated in the maintenance of CSC stemness. RNA-sequencing (RNA-seq) and ChIP-sequencing (ChIP-seq) were used to trace the lncRNA network regulated by p53-R273H in HCT116 endogenous p53 point mutant spheroid cells generated by the somatic cell knock-in method. RT-qPCR was used to detect lncRNA expression patterns, verifying the bioinformatics analysis. Transwell, spheroid formation, fluorescence activated cell sorter (FACS), xenograft nude mouse model, tumor frequency assessed by extreme limiting dilution analysis (ELDA), Western blot assays and chemoresistance analysis were performed to elucidate the functions and possible mechanism of lnc273–31 and lnc273–34 in cancer stem cells. p53-R273H exhibited more characteristics of CSC than p53-R175H and p53-R248W. RNA-seq profiling identified 37 up regulated and 4 down regulated differentially expressed lncRNAs regulated by p53-R273H. Combined with ChIP-seq profiling, we further verified two lncRNAs, named as lnc273–31 and lnc273–34, were essential in the maintenance of CSC stemness. Further investigation illustrated that lnc273–31 or lnc273–34 depletion dramatically diminished colorectal cancer migration, invasion, cancer stem cell self-renewal and chemoresistance in vitro. Moreover, the absence of lnc273–31 or lnc273–34 dramatically delayed cancer initiation and tumorigenic cell frequency in vivo. Also, lnc273–31 and lnc273–34 have an impact on epithelial-to mesenchymal transition (EMT). Finally, lnc273–31 and lnc273–34 were significantly highly expressed in CRC tissues with p53-R273H mutation compared to those with wildtype p53. The present study unveiled a high-confidence set of lncRNAs regulated by p53-R273H specific in colorectal CSCs. Furthermore, we demonstrated that two of them, lnc273–31 and lnc273–34, were required for colorectal CSC self-renewal, tumor propagation and chemoresistance. Also, the expression of these two lncRNAs augmented in colorectal cancer patient samples with p53-R273H mutation. These two lncRNAs may serve as promising predictors for patients with p53-R273H mutation and are vital for chemotherapy.

MAVS is essential for antiviral immunity, but the molecular mechanisms responsible for its tight regulation remain poorly understood. Here, we show that NLK inhibits the antiviral immune response during viral infection by targeting MAVS for degradation. NLK depletion promotes virus-induced antiviral cytokine production and decreases viral replication, which is potently rescued by the reintroduction of NLK. Moreover, the depletion of NLK promotes antiviral effects and increases the survival times of mice after infection with VSV. NLK interacts with and phosphorylates MAVS at multiple sites on mitochondria or peroxisomes, thereby inducing the degradation of MAVS and subsequent inactivation of IRF3. Most importantly, a peptide derived from MAVS promotes viral-induced IFN-β production and antagonizes viral replication in vitro and in vivo. These findings provide direct insights into the molecular mechanisms by which phosphorylation of MAVS regulates its degradation and influences its activation and identify an important peptide target for propagating antiviral responses.

Our previous work revealed that rhomboid domain-containing protein 1 (RHBDD1) participates in the modulation of cell growth and apoptosis in colorectal cancer cells. This study aimed to investigate the function of RHBDD1 in regulating breast cancer progression and its underlying molecular basis. Immunohistochemistry was performed to evaluate RHBDD1 expression in 116 breast cancer tissue and 39 adjacent normal tissue and expression of RHBDD1, phospho-Akt (p-Akt) and cyclin-dependent kinase 2 (CDK2) in the same 84 breast cancer specimens. RHBDD1-knock-out cells were established using breast cancer cell lines. In vitro studies were carried out to estimate the function of RHBDD1 in cell proliferation, migration and invasion. Fluorescence microscopy assay and flow cytometric analysis were used to measure apoptosis and cell cycle regulation. RNA sequencing and western blot analysis were used to investigate the molecular mechanisms of RHBDD1. RHBDD1 was highly up-regulated in breast cancer tissue compared with that in normal tissue and associated with pathological tumor (pT) stage, pathological tumor-node-metastasis (pTNM) stage and estrogen receptor (ER) expression. RHBDD1 up-regulation was associated with poor prognosis in several subtypes of breast cancer. Deletion of RHBDD1 promoted apoptosis and suppressed proliferation, migration and invasion in breast cancer cells. RHBDD1 deletion suppressed Akt activation and decreased CDK2 protein level via proteasome pathway, thus inhibited cell cycle progression and G1/S phase transition. Moreover, the protein level of RHBDD1, p-Akt and CDK2 was significantly positively correlated in breast cancer tissue. Our study reveals that RHBDD1 promotes breast cancer progression by regulating p-Akt and CDK2 protein levels, and might be a potential biomarker and prognostic indicator for breast cancer patients.

Long noncoding RNAs (lncRNAs) have emerged as diverse functional regulators involved in mammalian development; however, large-scale functional investigation of lncRNAs in mammalian spermatogenesis in vivo is lacking. Here, we delineated the global lncRNA expression landscape in mouse spermatogenesis and identified 968 germ cell signature lncRNAs. By combining bioinformatics and functional screening, we identified three functional lncRNAs (Gm4665,1700027A15Rik, and1700052I22Rik) that directly influence spermatogenesis in vivo. Knocking downGm4665hampered the development of round spermatids into elongating spermatids and disrupted key spermatogenic gene expression. Mechanistically, lncRNAGm4665localized in the nucleus of round spermatids and occupied the genomic regulatory region of important spermatogenic genes includingIp6k1andAkap3. These findings provide a valuable resource and framework for future functional analysis of lncRNAs in spermatogenesis and their potential roles in other biological processes.