Reversing effect of ring finger protein 43 inhibition on malignant phenotypes of human hepatocellular carcinoma

Whole genome sequencing of Malaysian colorectal cancer patients reveals specific druggable somatic mutations

The incidences of colorectal cancer (CRC) are continuously increasing in some areas of the world, including Malaysia. In this study, we aimed to characterize the landscape of somatic mutations using the whole-genome sequencing approach and identify druggable somatic mutations specific to Malaysian patients. Whole-genome sequencing was performed on the genomic DNA obtained from 50 Malaysian CRC patients' tissues. We discovered the top significantly mutated genes were APC, TP53, KRAS, TCF7L2 and ACVR2A. Four novel, non-synonymous variants were identified in three genes, which were KDM4E, MUC16 and POTED. At least one druggable somatic alteration was identified in 88% of our patients. Among them were two frameshift mutations in RNF43 (G156fs and P192fs) predicted to have responsive effects against the Wnt pathway inhibitor. We found that the exogenous expression of this RNF43 mutation in CRC cells resulted in increased cell proliferation and sensitivity against LGK974 drug treatment and G1 cell cycle arrest. In conclusion, this study uncovered our local CRC patients' genomic landscape and druggable alterations. It also highlighted the role of specific RNF43 frameshift mutations, which unveil the potential of an alternative treatment targeting the Wnt/β-Catenin signalling pathway and could be beneficial, especially to Malaysian CRC patients.

A pan-cancer analysis of ring finger protein 135 and its relationship to triple-negative breast cancer proliferation and metastasis

Ring finger protein 135 (RNF135) is an E3 ubiquitin ligase with RING finger domains that plays a crucial role in the development of several forms of cancer. Neither the expression profile of RNF135 nor its importance in the diagnosis of pan-cancer have been elucidated as of yet. With the aid of The Cancer Genome Atlas and Gene Expression Omnibus, we have fully mapped the expression profiles, prognostic relevance, genetic modification, immune cell infiltration, and tumor heterogeneity of RNF135 in 33 malignant tumors. RNF135 was expressed inconsistently in various cancers, and variations in RNF135 expression predicted survival outcomes for cancer patients. There was a strong correlation between the levels of the RNF135 genetic mutation and some tumor progression. In addition, a strong correlation was seen between RNF135 expression and immune cell infiltration, tumor mutation burden, microsatellite instability, and immunoregulators. In contrast, the correlation between RNF135 expression and triple-negative breast cancer was investigated in this study. RNF135 may boost the proliferation, migration, and invasion of TNBC cells, according to cell experiments. RNF135 might be utilized as a biomarker to anticipate how a tumor will behave and may have a significant role in how TNBC cells grow and migrate, according to the findings of this study.

The Role of Single-Nucleotide Polymorphisms in Cholangiocarcinoma: A Systematic Review

Single-nucleotide polymorphisms (SNPs) play an essential role in various malignancies, but their role in cholangiocarcinoma (CCA) remains to be elucidated. Therefore, the purpose of this systematic review was to evaluate the association between SNPs and CCA, focusing on tumorigenesis and prognosis. A systematic literature search was carried out using PubMed, Embase, Web of Science and the Cochrane database for the association between SNPs and CCA, including literature published between January 2000 and April 2022. This systematic review compiles 43 SNPs in 32 genes associated with CCA risk, metastatic progression and overall prognosis based on 34 studies. Susceptibility to CCA was associated with SNPs in genes related to inflammation (PTGS2/COX2, IL6, IFNG/IFN-γ, TNF/TNF-α), DNA repair (ERCC1, MTHFR, MUTYH, XRCC1, OGG1), detoxification (NAT1, NAT2 and ABCC2), enzymes (SERPINA1, GSTO1, APOBEC3A, APOBEC3B), RNA (HOTAIR) and membrane-based proteins (EGFR, GAB1, KLRK1/NKG2D). Overall oncological prognosis was also related to SNPs in eight genes (GNB3, NFE2L2/NRF2, GALNT14, EGFR, XRCC1, EZH2, GNAS, CXCR1). Our findings indicate that multiple SNPs play different roles at various stages of CCA and might serve as biomarkers guiding treatment and allowing oncological risk assessment. Considering the differences in SNP detection methods, patient ethnicity and corresponding environmental factors, more large-scale multicentric investigations are needed to fully determine the potential of SNP analysis for CCA susceptibility prediction and prognostication.

The genetic landscape of pancreatic head ductal adenocarcinoma in China and prognosis stratification

Background

Pancreatic ductal adenocarcinoma (PDAC) is the major subtype of pancreatic cancer and head PDACs show distinct characteristics from body/tail PDACs. With limited studies based on Asian population, the mutational landscape of Asian PDAC remains unclear.

Methods

One hundred fifty-one Chinese patients with head PDAC were selected and underwent targeted 425-gene sequencing. Genomic alterations, tumor mutational burden, and microsatellite instability were analyzed and compared with a TCGA cohort.

Results

The genomic landscape of Chinese and Western head PDAC had identical frequently-mutated genes including KRAS, TP53, SMAD4, and CDKN2A. KRAS hotspot in both cohorts was codon 12 but Chinese PDACs containing more G12V but fewer G12R variants. Potentially pathogenic fusions, CHD2-BRAF and KANK1-MET were identified in two KRAS wild-type patients. Serum cancer antigens CA125 and CA19-9 were positively associated with SMAD4 alterations while high CEA was enriched in wild-type CDKN2A subgroup. The probability of vascular invasion was lower in patients with RNF43 alterations. The nomogram developed including histology grade, the mutation status of SMAD4, TGFBR2, and PREX2 could calculate the risk score of prognoses validated by Chinese and TCGA cohort.

Conclusions

Chinese head PDAC contained more KRAS G12V mutation than Western population. The well-performed nomogram may improve post-operation care in real-world practice.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09279-9.

RNF43 as a predictor of malignant transformation of pancreatic mucinous cystic neoplasm

Mucinous cystic neoplasm (MCN) of the pancreas rarely progresses to invasive carcinoma, but few studies have analyzed genomic alterations involved in its malignant transformation. The relationships of ring finger protein 43 (RNF43) mutations with cytological atypia, RNF43 protein expression, and Wnt signaling proteins in MCN remain unclear. This study included 106 MCN cases, classified into 89 low-grade dysplasia (LG), 9 high-grade dysplasia (HG), and 8 invasive carcinoma (INV). We analyzed HG/INV and LG lesions of 9 HG/INV cases and LG lesions of 9 LG cases using targeted sequencing and confirmed the protein expression of RNF43 and β-catenin. The frequency of RNF43 mutations was significantly higher in HG/INV cases than in LG cases. Furthermore, HG/INV lesions (56%) and LG lesions (33%) of HG/INV cases possessed RNF43 mutation, whereas no such mutation was detected in any LG cases. The expression of RNF43 was reduced in 71% of HG/INV cases and significantly correlated with histological grade and aberrant expression of β-catenin. In 3 of 5 RNF43-mutated cases, the expression of RNF43 was reduced, but there was no significant correlation between RNF43 mutation and protein expression. MCNs frequently harbored KRAS mutations, at rates of 100% in HG/INV lesions and 50% in LG lesions of HG/INV and LG cases. There was no significant difference in mutation frequency in LG lesions between HG/INV and LG cases. These results suggest that RNF43 mutations may be involved in and predictive of malignant transformation from an early stage of MCN.

A DNA repair player, ring finger protein 43, relieves etoposide-induced topoisomerase II poisoning

Ring finger protein 43 (RNF43) is an E3 ubiquitin ligase which is well-known for its role in negative regulation of the Wnt-signaling pathway. However, the function in DNA double-strand break repairs has not been investigated. In this study, we used a lymphoblast cell line, DT40, and mouse embryonic fibroblast as cellular models to study DNA double-strand break (DSB) repairs. For this purpose, we created RNF43 knockout, RNF43^-/- DT40 cell line to investigate DSB repairs. We found that deletion of RNF43 does not interfere with cell proliferation. However, after exposure to various types of DNA-damaging agents, RNF43^-/- cells become more sensitive to topoisomerase II inhibitors, etoposide, and ICRF193, than wild type cells. Our results also showed that depletion of RNF43 results in apoptosis upon etoposide-mediated DNA damage. The delay in resolution of γH2AX and 53BP1 foci formation after etoposide treatment, as well as epistasis analysis with DNAPKcs, suggested that RNF43 might participate in DNA repair of etoposide-induced DSB via non-homologous end joining. Disturbed γH2AX foci formation in MEFs following pulse etoposide treatment supported the notion that RNF43 also functions DNA repair in mammalian cells. These findings propose two possible functions of RNF43, either participating in NHEJ or removing the blockage of 5' topo II adducts from DSB ends.

Commonly observed RNF43 mutations retain functionality in attenuating Wnt/β-catenin signaling and unlikely confer Wnt-dependency onto colorectal cancers

Cancer-associated RNF43 mutations lead to activation of β-catenin signaling through aberrantly increasing Wnt-receptor levels at the membrane. Importantly, inactivating RNF43 mutations have been suggested to render cancer cells sensitive to Wnt-based therapeutics. However, the extent to which RNF43 mutations lead to impaired regulation of Wnt/β-catenin signaling has been poorly investigated. Here, we observed that tumors with a functional mismatch repair system show a predominant 5'-location of truncating RNF43 mutations, suggesting C-terminal truncations such as the most commonly reported p.G659fs mutation, do not affect β-catenin signaling. In accordance, expressing C-terminal truncation mutants and wild-type RNF43, showed equal effects on β-catenin signaling, Wnt-receptor turnover, and DVL-binding. We confirmed these observations at endogenous levels by CRISPR-Cas9-mediated knockout of G659fs RNF43 expression in KM12 cells and generating comparable mutations in HEK293T cells. We could not confirm previous reports linking RNF43 to p53 and E-cadherin breakdown. Our data also suggest that only colorectal cancer cells harboring N-terminal mutations of RNF43 convey Wnt-dependency onto the tumor cells. Results of this study have potentially important clinical implications indicating that Wnt-based therapeutics should be applied cautiously in cancer patients harboring RNF43 mutations.

Bioinformatics analysis of gene expression profiles to diagnose crucial and novel genes in glioblastoma multiform

Therefore, the current study aimed to diagnose the genes associated in the pathogenesis of GBM. The differentially expressed genes (DEGs) were diagnosed using the limma software package. The ToppFun was used to perform pathway and Gene Ontology (GO) enrichment analysis of the DEGs. Protein-protein interaction (PPI) networks, extracted modules, miRNA-target genes regulatory network and miRNA-target genes regulatory network were used to obtain insight into the actions of DEGs. Survival analysis for DEGs carried out. A total of 701 DEGs, including 413 upregulated and 288 downregulated genes, were diagnosed between U1118MG cell line (PK 11195 treated with 1 h exposure) and U1118MG cell line (PK 11195 treated with 24 h exposure). The up-regulated genes were enriched in superpathway of pyrimidine deoxyribonucleotides de novo biosynthesis, cell cycle, cell cycle process and chromosome. The down-regulated genes were enriched in folate transformations I, biosynthesis of amino acids, cellular amino acid metabolic process and vacuolar membrane. The current study screened the genes in PPI network, extracted modules, miRNA-target genes regulatory network and miRNA-target genes regulatory network with higher degrees as hub genes, which included MYC, TERF2IP, CDK1, EEF1G, TXNIP, SLC1A5, RGS4 and IER5L Survival suggested that low expressed NR4A2, SLC7 A5, CYR61 and ID1 in patients with GBM was linked with a positive prognosis for overall survival. In conclusion, the current study could improve our understanding of the molecular mechanisms in the progression of GBM, and these crucial as well as new molecular markers might be used as therapeutic targets for GBM.

Optimized postconditioning algorithm protects liver graft after liver transplantation in rats

BACKGROUND

Ischemia reperfusion injury (IRI) causes postoperative complications and influences the outcome of the patients undergoing liver surgery and transplantation. Postconditioning (PostC) is a known manual conditioning to decrease the hepatic IRI. Here we aimed to optimize the applicable PostC protocols and investigate the potential protective mechanism.

METHODS

Thirty Sprague-Dawley rats were randomly divided into 3 groups: the sham group (n = 5), standard orthotopic liver transplantation group (OLT, n = 5), PostC group (OLT followed by clamping and re-opening the portal vein for different time intervals, n = 20). PostC group was then subdivided into 4 groups according to the different time intervals: (10 s × 3, 10 s × 6, 30 s × 3, 60 s × 3, n = 5 in each subgroup). Liver function, histopathology, malondialdehyde (MDA), myeloperoxidase (MPO), expressions of p-Akt and endoplasmic reticulum stress (ERS) related genes were evaluated.

RESULTS

Compared to the OLT group, the grafts subjected to PostC algorithm (without significant prolonging the total ischemic time) especially with short stimulus and more cycles (10 s × 6) showed significant alleviation of morphological damage and graft function. Besides, the production of reactive oxidative agents (MDA) and neutrophil infiltration (MPO) were significantly depressed by PostC algorithm. Most of ERS related genes were down-regulated by PostC (10 s × 6), especially ATF4, Casp12, hspa4, ATF6 and ELF2, while p-Akt was up-regulated.

CONCLUSIONS

PostC algorithm, especially 10 s × 6 algorithm, showed to be effective against rat liver graft IRI. These protective effects may be associated with its antioxidant, inhibition of ERS and activation of p-Akt expression of reperfusion injury salvage kinase pathway.

A phase I clinical trial of RNF43 peptide-related immune cell therapy combined with low-dose cyclophosphamide in patients with advanced solid tumors

The objective of this study was to investigate the safety and the tolerability of combined cellular immunotherapy with low-dose cyclophosphamide (CPA) in patients with advanced solid tumors. This study targeted a novel tumor-associated antigen, ring finger protein 43 (RNF43). Eligible patients were resistant to standard therapy, HLA-A*24:02- or A*02:01-positive and exhibiting high RNF43 expression in their tumor cells. They were administered 300 mg/m2 CPA followed by autologous lymphocytes, preliminarily cultured with autologous RNF43 peptide-pulsed dendritic cells (DCs), RNF43 peptide-pulsed DCs and systemic low dose interleukin-2. The primary endpoint was safety whereas the secondary endpoint was immunological and clinical response to treatment. Ten patients, in total, were enrolled in this trial. Primarily, no adverse events greater than Grade 3 were observed. Six out of 10 patients showed stable disease (SD) on day 49, while 4 other patients showed progressive disease. In addition, one patient with SD exhibited a partial response after the second trial. The frequency of regulatory T cells (Tregs) in patients with SD significantly decreased after CPA administration. The ratio of interferon-γ-producing, tumor-reactive CD8+ T cells increased with time in patients with SD. We successfully showed that the combination of immune cell therapy and CPA was safe, might induce tumor-specific immune responses and clinical efficacy, and was accompanied by a decreased ratio of Tregs in patients with RNF43-positive advanced solid tumors.

Statistically controlled identification of differentially expressed genes in one-to-one cell line comparisons of the CMAP database for drug repositioning

BACKGROUND

The Connectivity Map (CMAP) database, an important public data source for drug repositioning, archives gene expression profiles from cancer cell lines treated with and without bioactive small molecules. However, there are only one or two technical replicates for each cell line under one treatment condition. For such small-scale data, current fold-changes-based methods lack statistical control in identifying differentially expressed genes (DEGs) in treated cells. Especially, one-to-one comparison may result in too many drug-irrelevant DEGs due to random experimental factors. To tackle this problem, CMAP adopts a pattern-matching strategy to build "connection" between disease signatures and gene expression changes associated with drug treatments. However, many drug-irrelevant genes may blur the "connection" if all the genes are used instead of pre-selected DEGs induced by drug treatments.

METHODS

We applied OneComp, a customized version of RankComp, to identify DEGs in such small-scale cell line datasets. For a cell line, a list of gene pairs with stable relative expression orderings (REOs) were identified in a large collection of control cell samples measured in different experiments and they formed the background stable REOs. When applying OneComp to a small-scale cell line dataset, the background stable REOs were customized by filtering out the gene pairs with reversal REOs in the control samples of the analyzed dataset.

RESULTS

In simulated data, the consistency scores of overlapping genes between DEGs identified by OneComp and SAM were all higher than 99%, while the consistency score of the DEGs solely identified by OneComp was 96.85% according to the observed expression difference method. The usefulness of OneComp was exemplified in drug repositioning by identifying phenformin and metformin related genes using small-scale cell line datasets which helped to support them as a potential anti-tumor drug for non-small-cell lung carcinoma, while the pattern-matching strategy adopted by CMAP missed the two connections. The implementation of OneComp is available at https://github.com/pathint/reoa .

CONCLUSIONS

OneComp performed well in both the simulated and real data. It is useful in drug repositioning studies by helping to find hidden "connections" between drugs and diseases.

ZNRF3 is downregulated in papillary thyroid carcinoma and suppresses the proliferation and invasion of papillary thyroid cancer cells

Zinc and ring finger 3 (ZNRF3) is a transmembrane E3 ubiquitin ligase that has emerged as an important regulator of cancer development; however, its cancer-related function remains controversial. Here, we investigated the possible role of ZNRF3 in thyroid carcinoma (TC). We found that ZNRF3 is downregulated in papillary thyroid carcinoma (PTC) compared to normal thyroid tissues and inversely correlated with the degree of cell differentiation. Overexpression of ZNRF3 significantly suppressed cell malignant behaviors, including cell proliferation, migration, and invasion in vitro, as well as tumor growth in vivo. Consistent with recent studies showing that ZNRF3 is involved in the Wnt/β-catenin pathway, ZNRF3 overexpression negatively regulated β-catenin activation, modulating PTC cell behaviors. Clinical specimens revealed a significant inverse correlation between ZNRF3 and β-catenin mRNA levels. Taken together, these results provide insight into a potential tumor suppressor role of ZNRF3 in PTC progression, and may have potential clinical relevance for the prognosis and treatment of PTC.

Ring finger protein 43 expression is associated with genetic alteration status and poor prognosis among patients with intrahepatic cholangiocarcinoma

Ring finger E3 ligases have roles in processes central to maintenance of genomic integrity and cellular homeostasis. Many ring finger E3 ligases are implicated in malignancy. Ring finger protein 43 (RNF43) is a ring finger E3 ligase that negatively regulates the Wnt/β-catenin signaling pathway. RNF43 is frequently mutated in several types of malignancy, including intrahepatic cholangiocarcinoma (ICC). The significance of its expression in ICC has not, however, been reported. We determined RNF43 expression and identified RNF43 polymorphisms in ICC tissues. We also investigated the correlation between RNF43 expression and RNF43 mutation status, RNF43 polymorphisms, clinicopathological features, and prognosis of ICC patients. RNF43 reduced expression in ICC, and the reduction of RNF43 messenger RNA expression was significantly correlated with the presence of rs2257205 and RNF43 somatic mutations, confirming that all RNF43 somatic mutations in ICC are inactivating. Overall survival was worst in patients with down-regulation of RNF43. Univariate and multivariate analyses revealed that RNF43 expression was an independent prognostic factor. There was no statistically significant association between RNF43 messenger RNA and protein expression nor any clinicopathological features or RNF43 polymorphisms. The results imply that RNF43 is down-regulated in ICC and may play a crucial role during development of ICC.

RNF135, RING finger protein, promotes the proliferation of human glioblastoma cells in vivo and in vitro via the ERK pathway

Ring finger protein 135 (RNF135), located on chromosome 17q11.2, is a RING finger domain-containing E3 ubiquitin ligase that was identified as a bio-marker and therapy target of glioblastoma. In our study, we confirmed that RNF135 was up-regulated in glioblastoma tissues compared with normal brain (NB) tissues, and that RNF135 knockdown inhibited proliferation and migration and led to cell cycle arrest in the G0/G1 phase in vivo. By lowering RNF135 expression, phosphorylated Erk and cell cycle protein CDK4 were down-regulated, while p27^Kip1 and p21^Waf1/Cip1 were up-regulated in U87 and U251 cells in vitro. In addition, using the immunofluorescence double labelling method, we found that RNF135 and P-Erk were co-localized in the cytoplasm and were highly expressed in glioblastoma samples compared with NB tissues. Moreover, the growth of U87 cell-transplanted tumours in nude mice was inhibited while transduced with Lv-shRNF135. Taken together, our findings demonstrate the biological effects of RNF135 in glioblastoma cell proliferation, migration and cell cycle, and its role in the progression of glioblastoma may be associated with the ERK signal transduction pathway.

Oncogenic role of microRNA-423-5p in hepatocellular carcinoma

BACKGROUND

It has been found that microRNA-423-5p (miR423-5p) is an oncogenic factor and frequently upregulated in gastric carcinoma. However, the involvement of miR423-5p in hepatocellular carcinoma (HCC) has been rarely reported. The aim of this study was to assess whether miR423-5p is aberrantly expressed in HCC tissues, and to characterize its roles in the cancerous biology of HCC.

METHODS

HCC and corresponding nonmalignant tissues were obtained from 115 patients during liver transplantation to detect the expression level of miR423-5p. The miR423-5p mimic and inhibitor were transfected into LM3 cell line. Cell viability assay, cell cycle analysis, transwell invasion and migration experiments were used to evaluate the oncogenic role of miR423-5p.

RESULTS

miR423-5p was significantly upregulated in HCC compared with nonmalignant tissues, and this upregulation was negatively associated with recurrence-free survival. For patients beyond the Milan criteria, low expression of miR423-5p was correlated with better prognosis. Functional analysis showed that miR423-5p enhanced the proliferative, invasive and migratory capacity of HCC cells.

CONCLUSIONS

miR423-5p contributed to the tumorigenesis and progression of HCC. It could be a new predictor in HCC patients beyond the Milan criteria and would help to improve patient outcomes and enlarge recipient pools of liver transplantation.

The E3 ligase RNF43 inhibits Wnt signaling downstream of mutated β-catenin by sequestering TCF4 to the nuclear membrane

Given its fundamental role in development and cancer, the Wnt-β-catenin signaling pathway is tightly controlled at multiple levels. RING finger protein 43 (RNF43) is an E3 ubiquitin ligase originally found in stem cells and proposed to inhibit Wnt signaling by interacting with the Wnt receptors of the Frizzled family. We detected endogenous RNF43 in the nucleus of human intestinal crypt and colon cancer cells. We found that RNF43 physically interacted with T cell factor 4 (TCF4) in cells and tethered TCF4 to the nuclear membrane, thus silencing TCF4 transcriptional activity even in the presence of constitutively active mutants of β-catenin. This inhibitory mechanism was disrupted by the expression of RNF43 bearing mutations found in human gastrointestinal tumors, and transactivation of the Wnt pathway was observed in various cells and in Xenopus embryos when the RING domain of RNF43 was mutated. Our findings indicate that RNF43 inhibits the Wnt pathway downstream of oncogenic mutations that activate the pathway. Mimicking or enhancing this inhibitory activity of RNF43 may be useful to treat cancers arising from aberrant activation of the Wnt pathway.

Upregulated expression of polycomb protein Ring1 contributes to poor prognosis and accelerated proliferation in human hepatocellular carcinoma

Ring finger protein 1 (Ring1) have recently been reported to be closely related to aggressive tumor features in multiple cancer types, including prostate cancer, non-small-cell lung cancer, and bladder cancer. However, the role of Ring1 in human hepatocarcinogenesis remains unclear. In this study, we aimed at investigating the latent role of Ring1 in hepatocellular carcinoma (HCC) development. The expression of Ring1 was evaluated using Western blot analysis in 8 paired fresh HCC tissues and immunohistochemistry on 98 paraffin-embedded sections from 2005 to 2008. Moreover, RNA interference, CCK-8, colony formation, and flow-cytometry analyses were performed to investigate the role of Ring1 in the regulation of HCC cell proliferation. Compared with adjacent normal tissues, the level of Ring1 was significantly increased in HCC specimens. High expression of Ring1 was associated with histological grade (P = 0.011) and tumor size (P = 0.004), and Ring1 expression was positively related with the proliferation marker Ki-67 (P < 0.001). Moreover, knocking down Ring1 induced growth impairment and G1/S cell cycle arrest in HCC cells. Kaplan-Meier survival curves showed that high expression of Ring1 indicated poor prognosis of HCC (P = 0.03). On the basis of these results, we proposed that the expression of Ring1 protein may be a novel indicator of HCC prognosis.

The nucleoprotein of influenza A virus induces p53 signaling and apoptosis via attenuation of host ubiquitin ligase RNF43

The interplay between influenza virus and host factors to support the viral life cycle is well documented. Influenza A virus (IAV) proteins interact with an array of cellular proteins and hijack host pathways which are at the helm of cellular responses to facilitate virus invasion. The multifaceted nature of the ubiquitination pathway for protein regulation makes it a vulnerable target of many viruses including IAV. To this end we conducted a yeast two-hybrid screen to search for cellular ubiquitin ligases important for influenza virus replication. We identified host protein, RING finger protein 43 (RNF43), a RING-type E3 ubiquitin ligase, as a novel interactor of nucleoprotein (NP) of IAV and an essential partner to induce NP-driven p53-mediated apoptosis in IAV-infected cells. In this study, we demonstrate that IAV leads to attenuation of RNF43 transcripts and hence its respective protein levels in the cellular milieu whereas in RNF43 depleted cells, viral replication was escalated several folds. Moreover, RNF43 polyubiquitinates p53 which further leads to its destabilization resulting in a decrease in induction of the p53 apoptotic pathway, a hitherto unknown process targeted by NP for p53 stabilization and accumulation. Collectively, these results conclude that NP targets RNF43 to modulate p53 ubiquitination levels and hence causes p53 stabilization which is conducive to an enhanced apoptosis level in the host cells. In conclusion, our study unravels a novel strategy adopted by IAV for utilizing the much conserved ubiquitin proteasomal pathway.

Molecular Role of RNF43 in Canonical and Noncanonical Wnt Signaling

Wnt signaling pathways are tightly regulated by ubiquitination, and dysregulation of these pathways promotes tumorigenesis. It has been reported that the ubiquitin ligase RNF43 plays an important role in frizzled-dependent regulation of the Wnt/β-catenin pathway. Here, we show that RNF43 suppresses both Wnt/β-catenin signaling and noncanonical Wnt signaling by distinct mechanisms. The suppression of Wnt/β-catenin signaling requires interaction between the extracellular protease-associated (PA) domain and the cysteine-rich domain (CRD) of frizzled and the intracellular RING finger domain of RNF43. In contrast, these N-terminal domains of RNF43 are not required for inhibition of noncanonical Wnt signaling, but interaction between the C-terminal cytoplasmic region of RNF43 and the PDZ domain of dishevelled is essential for this suppression. We further show the mechanism by which missense mutations in the extracellular portion of RNF43 identified in patients with tumors activate Wnt/β-catenin signaling. Missense mutations of RNF43 change their localization from the endosome to the endoplasmic reticulum (ER), resulting in the failure of frizzled-dependent suppression of Wnt/β-catenin signaling. However, these mutants retain the ability to suppress noncanonical Wnt signaling, probably due to interaction with dishevelled. RNF43 is also one of the potential target genes of Wnt/β-catenin signaling. Our results reveal the molecular role of RNF43 and provide an insight into tumorigenesis.

Overexpression of collagen VI α3 in gastric cancer

Collagen VI is significant in the progression of numerous types of cancer. Type VI collagen consists of three α-chains and collagen VI α3 (COL6A3) encodes the α3 chain. The overexpression of COL6A3 has been demonstrated to correlate with high-grade ovarian cancer and contributes to cisplatin resistance; however, its role in human gastric cancer (GC) remains unclear. Using microarray meta-analysis, COL6A3 was observed to be frequently overexpressed in the GC tissues, furthermore, this overexpression was identified in five GC cell lines. A microarray-based co-expression network analysis was conducted and identified a total of 62 genes that were co-expressed with COL6A3, with the majority of the genes being involved in cancer-related processes, such as cell differentiation, migration and adhesion. Network analysis of these 62 genes demonstrated that fibronectin 1, a well-characterized oncogene, was located at the center of the COL6A3 co-expression network. Therefore, COL6A3 may act as an oncogene in human GC and the antagonism of COL6A3 may be an effective therapeutic treatment for GC.

Nanosecond pulsed electric field inhibits cancer growth followed by alteration in expressions of NF-κB and Wnt/β-catenin signaling molecules

Cancer remains a leading cause of death worldwide and total number of cases globally is increasing. Novel treatment strategies are therefore desperately required for radical treatment of cancers and long survival of patients. A new technology using high pulsed electric field has emerged from military application into biology and medicine by applying nsPEF as a means to inhibit cancer. However, molecular mechanisms of nsPEF on tumors or cancers are still unclear. In this paper, we found that nsPEF had extensive biological effects in cancers, and clarified its possible molecular mechanisms in vitro and in vivo. It could not only induce cell apoptosis via dependent-mitochondria intrinsic apoptosis pathway that was triggered by imbalance of anti- or pro-apoptosis Bcl-2 family proteins, but also inhibit cell proliferation through repressing NF-κB signaling pathway to reduce expressions of cyclin proteins. Moreover, nsPEF could also inactivate metastasis and invasion in cancer cells by suppressing Wnt/β-Catenin signaling pathway to down-regulating expressions of VEGF and MMPs family proteins. More importantly, nsPEF could function safely and effectively as an anti-cancer therapy through inducing tumor cell apoptosis, destroying tumor microenvironment, and depressing angiogenesis in tumor tissue in vivo. These findings may provide a creative and effective therapeutic strategy for cancers.

RNF43 mutations are recurrent in Chinese patients with mucinous ovarian carcinoma but absent in other subtypes of ovarian cancer

Ring finger protein 43 (RNF43) is an E3 ubiquitin-protein ligase that accepts ubiquitin from an E2 ubiquitin-conjugating enzyme and directly transfers the ubiquitin to targeted substrate proteins. Recently, large-scale sequencing efforts have identified prevalent RNF43 mutations in pancreatic and ovarian mucinous carcinomas. In the present study, we sequenced the entire coding sequences of RNF43 in 251 Chinese patients with distinct subtypes of ovarian cancers for the presence of RNF43 mutations. A total of 2 novel heterozygous nonsynonymous RNF43 mutations were identified in 2 out of 15 (13.3%) patients with mucinous ovarian carcinoma, these mutations were evolutionarily highly conserved; while no mutation was detected in other samples. In addition, none of the RNF43-mutated samples harbored DICER1 (dicer 1, ribonuclease type III), PPP2R1A (protein phosphatase 2, regulatory subunit A, alpha), TRRAP (transformation/transcription domain-associated protein) and DNMT3A (DNA (cytosine-5-)-methyltransferase 3 alpha) hot-spot mutations. Recurrent RNF43 mutations existed in mucinous ovarian carcinomas implicated that these mutations might play crucial roles in the tumorigenesis of these patients, while the absence of DICER1, PPP2R1A, TRRAP and DNMT3A hot-spot mutations suggested that these genetic alterations might not play synergistic roles with RNF43 mutations in these individuals. Additionally, the absence of RNF43 mutations in other subtypes of ovarian carcinoma implicated that RNF43 mutations might not be actively involved in the pathogenesis of these disorders.