ß-Catenin Sustains and Is Required for YES-associated Protein Oncogenic Activity in Cholangiocarcinoma.

BACKGROUND & AIMS: YES-associated protein (YAP) aberrant activation is implicated in intrahepatic cholangiocarcinoma (iCCA). Transcriptional enhanced associate domain (TEAD)-mediated transcriptional regulation is the primary signaling event downstream of YAP. The role of Wnt/ß-Catenin signaling in cholangiocarcinogenesis remains undetermined. Here, we investigated the possible molecular interplay between YAP and ß-Catenin cascades in iCCA. METHODS: Activated AKT (Myr-Akt) was coexpressed with YAP (YapS127A) or Tead2VP16 via hydrodynamic tail vein injection into mouse livers. Tumor growth was monitored, and liver tissues were collected and analyzed using histopathologic and molecular analysis. YAP, ß-Catenin, and TEAD interaction in iCCAs was investigated through coimmunoprecipitation. Conditional Ctnnb1 knockout mice were used to determine ß-Catenin function in murine iCCA models. RNA sequencing was performed to analyze the genes regulated by YAP and/or ß-Catenin. Immunostaining of total and nonphosphorylated/activated ß-Catenin staining was performed in mouse and human iCCAs. RESULTS: We discovered that TEAD factors are required for YAP-dependent iCCA development. However, transcriptional activation of TEADs did not fully recapitulate YAP's activities in promoting cholangiocarcinogenesis. Notably, ß-Catenin physically interacted with YAP in human and mouse iCCA. Ctnnb1 ablation strongly suppressed human iCCA cell growth and Yap-dependent cholangiocarcinogenesis. Furthermore, RNA-sequencing analysis revealed that YAP/ transcriptional coactivator with PDZ-binding motif (TAZ) regulate a set of genes significantly overlapping with those controlled by ß-Catenin. Importantly, activated/nonphosphorylated ß-Catenin was detected in more than 80% of human iCCAs. CONCLUSION: YAP induces cholangiocarcinogenesis via TEAD-dependent transcriptional activation and interaction with ß-Catenin. ß-Catenin binds to YAP in iCCA and is required for YAP full transcriptional activity, revealing the functional crosstalk between YAP and ß-Catenin pathways in cholangiocarcinogenesis.

CircNFIB inhibits tumor growth and metastasis through suppressing MEK1/ERK signaling in intrahepatic cholangiocarcinoma.

BACKGROUND: Considerable evidence shows that circular RNAs (circRNAs) play an important role in tumor development. However, their function in intrahepatic cholangiocarcinoma (ICC) metastasis and the underlying mechanisms are incompletely understood. METHODS: circNFIB (hsa_circ_0086376, termed as cNFIB hereafter) was identified in human ICC tissues through circRNAs sequencing. The biological role of cNFIB was determined in vitro and in vivo by gain or loss of functional experiments. Fluorescence in situ hybridization (FISH), RNA immunoprecipitation (RIP) and RNA pull-down assays were conducted to analyze the interaction of cNFIB with dual specificity mitogen-activated protein kinase kinase1 (MEK1). Duolink in situ proximity ligation assay (PLA) and coimmunoprecipitation (co-IP) assay were used to investigate the effects of cNFIB on the interaction between MEK1 and mitogen-activated protein kinase 2 (ERK2). Finally, a series of in vitro and in vivo experiments were performed to explore the influences of cNFIB on the anti-tumor activity of trametinib (a MEK inhibitor). RESULTS: cNFIB was significantly down-regulated in human ICC tissues with postoperative metastases. The loss of cNFIB was highly associated with aggressive characteristics and predicted unfavorable prognosis in ICC patients. Functional studies revealed that cNFIB inhibited the proliferation and metastasis of ICC cells in vitro and in vivo. Mechanistically, cNFIB competitively interacted with MEK1, which induced the dissociation between MEK1 and ERK2, thereby resulting in the suppression of ERK signaling and tumor metastasis. Moreover, we found that ICC cells with high levels of cNFIB held the potential to delay the trametinib resistance. Consistently, in vivo and in vitro studies demonstrated that cotreatment with trametinib and lentivirus vector encoding cNFIB showed greater inhibitory effect than isolated trametinib treatment. CONCLUSIONS: Our findings identified that cNFIB played a key role in ICC growth and metastasis by regulating MEK1/ERK signaling. Given the efficacy of cNFIB modulation on ICC suppression and trametinib sensitivity, cNFIB appears to be a potential therapeutic molecule for ICC treatment.

KIAA1429 contributes to liver cancer progression through N6-methyladenosine-dependent post-transcriptional modification of GATA3.

BACKGROUND: N6-methyladenosine (m6A) modification, the most abundant internal methylation of eukaryotic RNA transcripts, is critically implicated in RNA processing. As the largest known component in the m6A methyltransferase complex, KIAA1429 plays a vital role in m6A methylation. However, its function and mechanism in hepatocellular carcinoma (HCC) remain poorly defined. METHODS: Quantitative PCR, western blot and immunohistochemistry were used to measure the expression of KIAA1429 in HCC. The effects of KIAA1429 on the malignant phenotypes of hepatoma cells were examined in vitro and in vivo. MeRIP-seq, RIP-seq and RNA-seq were performed to identify the target genes of KIAA1429. RESULTS: KIAA1429 was considerably upregulated in HCC tissues. High expression of KIAA1429 was associated with poor prognosis among HCC patients. Silencing KIAA1429 suppressed cell proliferation and metastasis in vitro and in vivo. GATA3 was identified as the direct downstream target of KIAA1429-mediated m6A modification. KIAA1429 induced m6A methylation on the 3' UTR of GATA3 pre-mRNA, leading to the separation of the RNA-binding protein HuR and the degradation of GATA3 pre-mRNA. Strikingly, a long noncoding RNA (lncRNA) GATA3-AS, transcribed from the antisense strand of the GATA3 gene, functioned as a cis-acting element for the preferential interaction of KIAA1429 with GATA3 pre-mRNA. Accordingly, we found that the tumor growth and metastasis driven by KIAA1429 or GATA3-AS were mediated by GATA3. CONCLUSION: Our study proposed a complex KIAA1429-GATA3 regulatory model based on m6A modification and provided insights into the epi-transcriptomic dysregulation in hepatocarcinogenesis and metastasis.

Structural Insights into the Pharmacophore of Vinca Domain Inhibitors of Microtubules.

Antibody-drug conjugates (ADCs) have achieved great success in cancer therapy in recent years. Some peptidyl microtubule inhibitors consisting of natural and unnatural amino acids, such as monomethyl auristatin E (MMAE) and F (MMAF), are extremely cytotoxic and have been used as a payload in ADCs. However, their precise molecular interaction with tubulin and microtubules remains unclear. We determined the crystal structures of tubulin in complex with three ultra-potent peptidyl microtubule inhibitors [MMAE, taltobulin (HTI- 286), and tubulysin M] at 2.5 Å. Our data showed that the three peptides bound to the vinca domain and shared a common and key pharmacophore containing two consecutive hydrophobic groups (Val, Ile-like side chain). These groups protruded in opposite directions into hydrophobic pockets on the tubulin ß and α subunits. Nitrogen and oxygen atoms from the same backbone formed hydrogen bonds with Asn329 from the α subunit and Asp179 from the ß subunit in a direction normal to the surface formed by the aforementioned hydrophobic groups. In addition, our crystal structure data indicated that tubulysin M bound to the ß subunit alone, providing a structural explanation for its higher affinity. We also compared the conformations of two representative structurally different vinca domain compounds, ustiloxin D and vinblastine, with those of the aforementioned peptidyl ligands, and found that they shared a similar pharmacophore. Our findings lay a foundation for the rational design of novel vinca domain ligands and may facilitate the development of microtubule inhibitors with high specificity, affinity, and efficiency as payloads for ADCs in cancer therapy.

CTHRC1 promotes colorectal cancer progression by recruiting tumor-associated macrophages via up-regulation of CCL15.

Tumor-associated macrophages (TAMs) represent a key factor in the tumor immune microenvironment (TME), exerting significant influence over tumor migration, invasion, immunosuppressive features, and drug resistance. Collagen triple helix repeat containing 1 (CTHRC1), a 30 KDa protein which was secreted during the tissue-repair process, is highly expressed in several malignant tumors, including colorectal cancer (CRC). Previous studies demonstrated that CTHRC1 expression in TAMs was positively correlated to M2 macrophage polarization and liver metastasis, while our discovery suggesting a novel mechanism that CTHRC1 secreted from cancer cell could indirectly interplay with TAMs. In this study, the high expression level of CTHRC1 was evaluated in CRC based on GEO and TCGA databases. Further, CTHRC1 was detected high in all stages of CRC patients by ELISA and was correlated to poor prognosis. Multispectral imaging of IHC demonstrated that M2 macrophage infiltration was increased accompanied with CTHRC1 enrichment, suggesting that CTHRC1 may have chemotactic effect on macrophages. In vitro, CTHRC1 could have chemotactic ability of macrophage in the presence of HT-29 cell line. Cytokine microarray revealed that CTHRC1 could up-regulate the CCL15 level of HT-29, pathway analysis demonstrated that CTHRC1 could regulate CCL15 by controlling the TGFß activation and Smad phosphorylation level. In vivo, knocking down of CTHRC1 from CT-26 also inhibits tumor formation. In conclusion, CTHRC1 could promote the chemotactic ability of macrophages by up-regulating CCL15 via TGFß/Smad pathway; additionally, a high level of CTHRC1 could promote macrophage's M2 polarization. This discovery may be related to tumor immune tolerance and tumor immunotherapy resistance in CRC. KEY MESSAGES: CTHRC1 promotes CRC progression by up-regulating CCL15 via TGF-ß/Smad pathways to further recruit tumor-associated macrophages. By the means of autocrine or paracrine, CTHRC1 can indeed promote macrophage chemotaxis and enhance the infiltration of macrophages in tumor tissues but in the presence of tumor cells. CAFs were another source of CTHRC1, indicating CTHRC1 can infiltrate tumor islet as well as the stomal and be secreted from both tumor cells and CAFs. This study validated CTHRC1 as a potential immune therapy target CRC.

Risk factors of postoperative bile leakage after liver resection: A systematic review and meta-analysis.

OBJECTIVE: Postoperative bile leakage (POBL) is one of the most common complications after liver resection. However, current studies on the risk factors for POBL and their impacts on surgical outcomes need to be more consistent. This study aims to conduct a meta-analysis to analyze the risk factors for POBL after hepatectomy. METHODS: We incorporated all eligible studies from Embase, PubMed, and the Web of Science database (until July 2022) into this study. RevMan and STATA software were used to analyze the extracted data. RESULTS: A total of 39 studies, including 43,824 patients, were included in this meta-analysis. We found that gender, partial hepatectomy, repeat of hepatectomy, extended hepatectomy, abdominal drain, diabetes, Child≥B, solitary tumor, and chemotherapy are the factors of grade B and C POBL. Some recognized risk factors were considered potential risk factors for grade B and C bile leakage because no subgroup analysis was performed, like HCC, cholangiocarcinoma, major resection, posterior sectionectomy, bi-segmentectomy, S4 involved, S8 involved, central hepatectomy, and bile duct resection/reconstruction. Meanwhile, cirrhosis, benign diseases, left hepatectomy, and Segment 1 resection were not significant for grade B and C bile leakage. The influence of lateral sectionectomy, anterior sectionectomy, S1 involved, S3 involved, high-risk procedure, laparoscope, and blood loss>1000 mL on POBL of ISGLS needs further research. Meanwhile, POBL significantly influenced overall survival (OS) after liver resection. CONCLUSIONS: We identified several risk factors for POBL after hepatectomy, which could prompt the clinician to decrease POBL rates and make more beneficial decisions for patients who underwent the hepatectomy.

Circular RNAs in cholangiocarcinoma.

Cholangiocarcinoma (CCA) is the most common primary biliary malignancy with an adverse prognosis. Although its incidence is relatively low, early diagnosis is difficult due to the lack of specific symptoms. Current treatment options for CCA are limited, resulting in a low curative rate. Circular RNAs (circRNAs) have become a new research hotspot in recent years, and they are frequently dysregulated in CCA and may become therapeutic targets and prognostic biomarkers of CCA. Accumulating evidence has demonstrated that numerous dysregulated circRNAs are vital players in the etiopathogenesis of CCA. Aberrant expression of specific circRNAs was correlated with unfavourable clinical characteristics in CCA. Many studies have found that circRNAs are involved in the progression and development of CCA through various mechanisms, including competitive inhibition of miRNAs via the competing endogenous RNA (ceRNA) network, interaction with RNA-binding proteins (RBPs), activation of cancer-related signalling pathways, and regulation of proteins and peptides. Additionally, some circRNAs are involved in the inflammatory microenvironment of CCA and play a crucial role in chemotherapy drug resistance. Thus, they are essential for the early diagnosis and prediction of CCA, and more attention should be given to the roles and mechanisms of circRNAs in CCA. In this review, we summarize the abnormal expression of circRNAs in CCA and the specific inflammatory microenvironment involved, as well as the roles and mechanisms of circRNAs in the occurrence and development of CCA. We also review the latest knowle dge on circRNAs in CCA and discuss the challenges associated with the introduction of circRNAs into clinical practice and their potential clinical value.

CircZNF215 promotes tumor growth and metastasis through inactivation of the PTEN/AKT pathway in intrahepatic cholangiocarcinoma.

BACKGROUND: Increasing evidence shows that circular RNAs (circRNAs), a novel class of noncoding RNAs, play a crucial role in the development of cancers, including intrahepatic cholangiocarcinoma (iCCA). Nevertheless, their functions and exact mechanisms in iCCA progression and metastasis are still unclear. Ipatasertib is a highly selective inhibitor of AKT that inhibits tumor growth by blocking the PI3K/AKT pathway. In addition, phosphatase and tensin homolog (PTEN) can also inhibit the activation of the PI3K/AKT pathway, but it is not clear whether the cZNF215-PRDX-PTEN axis plays a role in the antitumor activity of ipatasertib. METHODS: We identified a new circRNA (circZNF215, termed cZNF215) through high-throughput circRNA sequencing (circRNA-seq). In addition, RT‒qPCR, immunoblot assay, RNA pull-down assay, RNA immunoprecipitation (RIP) assay, and fluorescence in situ hybridization assay (FISH) were used to investigate the interaction of cZNF215 with peroxiredoxin 1 (PRDX1). Coimmunoprecipitation (Co-IP) assays and duolink in situ proximity ligation assays (PLAs) were conducted to analyze the effects of cZNF215 on the interaction between PRDX1 and PTEN. Finally, we tested the potential effects of cZNF215 on the antitumor activity of ipatasertib with in vivo experiments. RESULTS: We found that cZNF215 expression was obviously upregulated in iCCA tissues with postoperative metastases and was correlated with iCCA metastasis and poor outcome in patients with iCCA. We further revealed that overexpression of cZNF215 promoted iCCA cell growth and metastasis in vitro and in vivo, while cZNF215 knockdown had the opposite effect. Mechanistic studies suggested that cZNF215 competitively interacted with PRDX1, which blocked the association between PRDX1 and PTEN, subsequently leading to oxidation-induced inactivation of the PTEN/AKT pathway and finally contributing to iCCA progression and metastasis. Additionally, we also revealed that silencing cZNF215 in iCCA cells had the potential to enhance the antitumor effect of ipatasertib. CONCLUSIONS: Our study demonstrates that cZNF215 facilitates iCCA progression and metastasis by regulating the PTEN/AKT pathway and may serve as a novel prognostic predictor in patients with iCCA.

MDIG-mediated H3K9me3 demethylation upregulates Myc by activating OTX2 and facilitates liver regeneration.

The mineral dust-induced gene (MDIG) comprises a conserved JmjC domain and has the ability to demethylate histone H3 lysine 9 trimethylation (H3K9me3). Previous studies have indicated the significance of MDIG in promoting cell proliferation by modulating cell-cycle transition. However, its involvement in liver regeneration has not been extensively investigated. In this study, we generated mice with liver-specific knockout of MDIG and applied partial hepatectomy or carbon tetrachloride mouse models to investigate the biological contribution of MDIG in liver regeneration. The MDIG levels showed initial upregulation followed by downregulation as the recovery progressed. Genetic MDIG deficiency resulted in dramatically impaired liver regeneration and delayed cell cycle progression. However, the MDIG-deleted liver was eventually restored over a long latency. RNA-seq analysis revealed Myc as a crucial effector downstream of MDIG. However, ATAC-seq identified the reduced chromatin accessibility of OTX2 locus in MDIG-ablated regenerating liver, with unaltered chromatin accessibility of Myc locus. Mechanistically, MDIG altered chromatin accessibility to allow transcription by demethylating H3K9me3 at the OTX2 promoter region. As a consequence, the transcription factor OTX2 binding at the Myc promoter region was decreased in MDIG-deficient hepatocytes, which in turn repressed Myc expression. Reciprocally, Myc enhanced MDIG expression by regulating MDIG promoter activity, forming a positive feedback loop to sustain hepatocyte proliferation. Altogether, our results prove the essential role of MDIG in facilitating liver regeneration via regulating histone methylation to alter chromatin accessibility and provide valuable insights into the epi-transcriptomic regulation during liver regeneration.

DOG1 as a novel antibody-drug conjugate target for the treatment of multiple gastrointestinal tumors and liver metastasis.

Discovered On Gastrointestinal stromal tumors protein 1 (DOG1), a major calcium-activated chloride channel, has been used as a common diagnostic marker for gastrointestinal stromal tumors. However, the therapeutic application of DOG1 was not well defined. Here, we aim to investigate its potential as a therapeutic target for an antibody-drug conjugate (ADC) in various cancers of the alimentary tract and metastasis. The DOG1 expression profile was determined among TCGA samples and tissue microarrays. High levels of DOG1 expression were ubiquitously observed in multiple cancer samples from the alimentary tract determined by TCGA samples and tissue microarrays. Circulating tumor cells isolated from metastatic colon cancer patients were also positive for DOG1 expression. The mechanisms of anti-DOG1 antibody were investigated by dual-luciferase reporter assay. The anti-DOG1 antibody could inhibit proliferation and metastasis via p53 signaling in limited cancer cell lines. The anti-DOG1 antibody was conjugated with a microtubule inhibitor DM4, to construct a new anti-DOG1-DM4-ADC to strengthen its activity. The anti-DOG1-DM4-ADC showed cytotoxicity at the nanomolar level in vitro. In the murine xenograft tumor models, treatment of anti-DOG1-DM4-ADC achieved a significant tumor growth inhibition rate. Our study indicates that anti-DOG1-DM4-ADC may be promising therapeutic molecules for DOG1-positive alimentary tract tumors and may be effective in inhibiting recurrence after curative resection of liver metastases of colorectal origin.

Epigenome-wide development and validation of a prognostic methylation score in intrahepatic cholangiocarcinoma based on machine learning strategies.

Background: Clinical parameter-based nomograms and staging systems provide limited information for the prediction of survival in intrahepatic cholangiocarcinoma (ICC) patients. In this study, we developed a methylation signature that precisely predicts overall survival (OS) after surgery. Methods: An epigenome-wide study of DNA methylation based on whole-genome bisulfite sequencing (WGBS) was conducted for two independent cohorts (discovery cohort, n=164; validation cohort, n=170) from three hepatobiliary centers in China. By referring to differentially methylated regions (DMRs), we proposed the concept of prognostically methylated regions (PMRs), which were composed of consecutive prognostically methylated CpGs (PMCs). Using machine learning strategies (Random Forest and the least absolute shrinkage and selector regression), a prognostic methylation score (PMS) was constructed based on 14 PMRs in the discovery cohort and confirmed in the validation cohort. Results: The C-indices of the PMS for predicting OS in the discovery and validation cohorts were 0.79 and 0.74, respectively. In the whole cohort, the PMS was an independent predictor of OS [hazard ratio (HR) =8.12; 95% confidence interval (CI): 5.48-12.04; P<0.001], and the C-index (0.78) of the PMS was significantly higher than that of the Johns Hopkins University School of Medicine (JHUSM) nomogram (0.69, P<0.001), the Eastern Hepatobiliary Surgery Hospital (EHBSH) nomogram (0.67, P<0.001), American Joint Committee on Cancer (AJCC) tumor-node-metastasis (TNM) staging system (0.61, P<0.001), and MEGNA prognostic score (0.60, P<0.001). The patients in quartile 4 of PMS could benefit from adjuvant therapy (AT) (HR =0.54; 95% CI: 0.32-0.91; log-rank P=0.043), whereas those in the quartiles 1-3 could not. However, other nomograms and staging system failed to do so. Further analyses of potential mechanisms showed that the PMS was associated with tumor biological behaviors, pathway activation, and immune microenvironment. Conclusions: The PMS could improve the prognostic accuracy and identify patients who would benefit from AT for ICC patients, and might facilitate decisions in treatment of ICC patients.

[Analysis of gene expression patterns in an irinotecan-resistance colon cancer cell by cDNA microarray].

OBJECTIVE: To study the mechanism of irinotecan-resistant colon cancer by analyzing the differential gene expression patterns with cDNA microarray. METHODS: Total RNA was purified from irinotecan-sensitive colonic cancer cell line, SW480 and its irinotecan-resistance cell line, SW480/CPT. The cRNA retro-transcribed from RNA were labeled with Cy3 fluorescence as probes. The probes were hybridized with Agilent gene chips and the fluorescence images of the chips were obtained with Axon 4000B scanner as well as analyzed with Genepix 3.0 software. The microarray results were confirmed by reverse transcription-polymerase chain reaction. RESULTS: Of the 1598 genes with altered expressions, there were 911 up-regulated genes and 687 down-regulated genes. Glutathione S-Transferase (GST) isoenzyme family GSTA such as GSTA1, GSTA2, GSTA3 and GSTA5 were significantly up-regulated. The expression levels of many Zinc finger protein family members (ZNF) were also differentially regulated. CONCLUSION: GSTA and ZNF subunit genes might play an important regulation role in the irinotecan resistance of colon cancer.

Nomogram Models for Predicting Risk and Prognosis of Newly Diagnosed Ovarian Cancer Patients with Liver Metastases - A Large Population-Based Real-World Study.

Background: Previous studies about liver metastases (LM) in newly diagnosed ovarian cancer (NDOC) patients based on Surveillance, Epidemiology, and End Results (SEER) program disregarded selection bias of missing data. Methods: We identified Data of NDOC patients from SEER between 2010 and 2016, presented a comprehensive description of this dataset, and limited possible biases due to missing data by applying multiple imputation (MI). We determined predictive factors for underlying LM development in NDOC patients and evaluated prognostic factors in NDOC patients with LM (OCLM). We then established predictive nomograms, assessed by the concordance index, calibration curve, decision curve analysis (DCA), and clinical impact curves (CIC). Results: The amount of missing data for different variables in SEER dataset ranges from 0 to 36.11%. The results between complete dataset and MI datasets are similar. LM prevalence in NDOC patients was 7.18%, and median overall survival for OCLM patients was 11 months. The C-index of risk nomogram for LM development in the training cohort (TC) and validation cohort (VC) were 0.764 and 0.759, respectively. The C-index and integrated area under curve within five years of prognostic nomogram for OCLM patients in the TC and VC were 0.743 and 0.773, 0.714 and 0.733, respectively. For both nomograms, DCA revealed favorable clinical use and calibration curves suggested good consistency. Conclusion: The risk nomogram is expected to aid clinicians in identifying high-risk groups of LM development in NDOC patients for intensive screening. The prognostic nomogram could facilitate individualized prediction and stratification for clinical trials in OCLM patients.

Circular RNA circDLC1 inhibits MMP1-mediated liver cancer progression via interaction with HuR.

Rationale: circular RNAs (circRNAs) have been demonstrated to play a crucial role in cancer progression. KIAA1429, a key component of the m6A methyltransferase complex, has recently been reported to promote hepatocellular carcinoma (HCC) progression by regulating the m6A methylation. The aim of present study is to investigate the role of circular RNAs in KIAA1429-mediated HCC progression. Methods: RNA sequencing (RNA-seq) and methylated RNA immunoprecipitation sequencing (m6A-seq) were utilized to identify KIAA1429-regulated circRNAs. The effects of circDLC1 on proliferation and metastasis of hepatoma cells were examined in vitro and in vivo. RT-qPCR was used to measure the expression of circDLC1 in HCC tissues and hepatoma cells. RNA FISH, RIP assays and biotin-labeled RNA pull-down were used to investigate the downstream effector of circDLC1. The downstream targets of circDLC1 were identified using RNA-seq. Results: Our data demonstrated that circDLC1 was downregulated in HCC tissues and closely relevant to favorable prognosis. Overexpression of circDLC1 inhibited the proliferation and motility of hepatoma cells in vitro and in vivo, while silencing of circDLC1 played the opposite role. Mechanistic investigations revealed that circDLC1 could bind to RNA-binding protein HuR, which subsequently reduced the interaction between HuR and MMP1 mRNAs, and thus inhibited the expression of MMP1, ultimately contributing to inhibition of HCC progression. Conclusion: Our work suggests that circDLC1, a downstream target of KIAA1429, is a promising prognostic marker for HCC patients, and the circDLC1-HuR-MMP1 axis may serve as a potential therapeutic target for HCC treatment.

Claudin-2 promotes colorectal cancer growth and metastasis by suppressing NDRG1 transcription.

Colorectal cancer (CRC) is one of the most common malignant tumours, with multiple driving factors and biological transitions involved in its development. Claudin-2 (CLDN2), a well-defined component of cellular tight junction, has been indicated to associate with CRC progression. However, the function of CLDN2 and the underlying mechanism whereby the downstream signalling transduction is regulated in CRC remains largely unclear. In this study, we demonstrated that CLDN2 is upregulated in CRC samples and associated with poor survival. And CLDN2 depletion significantly promotes N-myc downstream-regulated gene 1 (NDRG1) transcription, leading to termination of the CRC growth and metastasis in vitro and in vivo. Mechanistically, this process promotes CLDN2/ZO1/ZONAB complex dissociation and ZONAB shuttle into nucleus to enrich in the promoter of NDRG1. Thus, this study reveals a novel CLDN2/ZO1/ZONAB-NDRG1 axis in CRC by regulating the expression of EMT-related genes and CDKIs, suggesting CLDN2 may serve as a promising target for CRC treatment.

NCSTN promotes hepatocellular carcinoma cell growth and metastasis via ß-catenin activation in a Notch1/AKT dependent manner.

BACKGROUND: Hepatocellular carcinoma is the third top cause of cancer-related mortalities worldwide. The prognosis of HCC patients remains poor due to rapid progression and high incidence of tumor recurrence. Nicastrin (NCSTN), a core subunit of γ-Secretase, has been reported to play a vital role in tumor progression. However, no study till now has revealed its role in HCC. METHODS: The expression of NCSTN was evaluated by immunohistochemical staining, Western blot, and quantitative real-time PCR. Cell counting kit-8, colony formation and cell cycle assays were used for evaluating cell growth in vitro. Transwell and wound-healing assays were used for evaluating cell migration and invasion capacity. Immunofluorescence, subcellular protein fractionation and co-immunoprecipitation were used for location analysis of ß-catenin. The in vivo functions of NCSTN were illustrated by xenograft tumor models. RESULTS: NCSTN was dramatically overexpressed in HCC compared to normal liver tissues. Elevated NCSTN expression level was significantly correlated to worse overall and recurrence-free survival of HCC patients. Enhanced NCSTN expression promoted HCC cell growth, migration and invasion in vitro and in vivo. Mechanistic investigations showed that NCSTN induced epithelial-mesenchymal transition (EMT) process via upregulation of Zeb1. Subsequently, we revealed that NCSTN facilitated nuclear translocation of ß-catenin, a positive transcriptional regulator of Zeb1. Using Notch and AKT inhibitors, we revealed that NCSTN promoted ß-catenin activation through Notch1 and AKT signaling pathway. NCSTN increased AKT and GSK-3ß phosphorylation by cleavage of Notch1, which decreased GSK-3ß/ß-catenin complex. The inactivation of GSK-3ß inhibited the ß-catenin degradation and promoted nuclear translocation of ß-catenin to initiate transcription of Zeb1, resulting in malignant phenotype. CONCLUSIONS: Our results demonstrated that NCSTN promoted HCC cell growth and metastasis via ß-catenin-mediated upregulation of Zeb1 in a Notch1/AKT dependent manner, suggesting that NCSTN might serve as a potential prognostic marker and therapeutic target for HCC.

TXNDC12 promotes EMT and metastasis of hepatocellular carcinoma cells via activation of ß-catenin.

Metastasis is one of the main contributors to the poor prognosis of hepatocellular carcinoma (HCC). However, the underlying mechanism of HCC metastasis remains largely unknown. Here, we showed that TXNDC12, a thioredoxin-like protein, was upregulated in highly metastatic HCC cell lines as well as in portal vein tumor thrombus and lung metastasis tissues of HCC patients. We found that the enforced expression of TXNDC12 promoted metastasis both in vitro and in vivo. Subsequent mechanistic investigations revealed that TXNDC12 promoted metastasis through upregulation of the ZEB1-mediated epithelial-mesenchymal transition (EMT) process. We subsequently showed that TXNDC12 overexpression stimulated the nuclear translocation and activation of ß-catenin, a positive transcriptional regulator of ZEB1. Accordingly, we found that TXNDC12 interacted with ß-catenin and that the thioredoxin-like domain of TXNDC12 was essential for the interaction between TXNDC12 and ß-catenin as well as for TXNDC12-mediated ß-catenin activation. Moreover, high levels of TXNDC12 in clinical HCC tissues correlated with elevated nuclear ß-catenin levels and predicted worse overall and disease-free survival. In summary, our study demonstrated that TXNDC12 could activate ß-catenin via protein-protein interaction and promote ZEB1-mediated EMT and HCC metastasis.

[Cultivation and characterization of tumor spheres generated from human colorectal cancer cell lines].

OBJECTIVE: To study on the cultivation method for tumor spheres from colorectal cancer cell lines and identify whether resulting Colo205 spheroid cells display cancer stem cell characteristics. METHODS: Lovo, Colo205 and SW480 cells were seeded in serum free medium (SFM) with EGF and bFGF. Flow cytometry analysis, cell invasion assay and xenograft experiment were applied to examine the cell surface marker expression pattern, cell invasive ability and in vivo tumorigenicity of both Colo205 spheres and parental cells. CD44 expression of tumor spheroid cells was also analyzed after cultured with serum supplemented medium by flow cytometry. CD44, Musashi-1 and Oct4 mRNA were detected in these two cells by RT-PCR. RESULTS: Tumor spheres could be generated from three colorectal cancer cell lines in SFM. The formation and proliferation of tumor spheres were benefited from fresh SFM, cell dissociation reagent Accutase and the floating status of cancer cells. The overwhelming majority of spheroid cells were CD44+ cells. But CD44+ cells were gradually decreased when spheres cultured with serum supplemented medium. Colo205 spheres have higher Musashi-1 and Oct4 mRNA expression, tumor-initiating capability and invasive ability compared with those of parental cells. CONCLUSION: Tumor spheres in which enrich cancer stem cells can be generated and matained from colorectal cancer cell lines in SFM on floating-culture condition.

[The effect of Rac1 siRNA on the biological behaviors of gastrointestinal cancer cells].

OBJECTIVE: To explore the effect of Rac1 siRNA on the expression of Rac1 and the biological behaviors of gastrointestinal cancer cells. METHODS: Rac1 siRNA was transfected into human gastric cancer cell line SGC803 and colorectal cancer cell line Lovo by lipofectamine 2000. The expression of Rac1 in these cell lines were detected by Western blot and RT-PCR after 48 hours of the transfection. The effect of Rac1 on the proliferation of human gastric cancer cell line SGC803 and colorectal cancer cell line Lovo were tested by CCK8 kit. The motility of the transfected and the control cancer cells were assessed by Wound-healing assay and invasion assay. The apoptotic index was evaluated by Hoechst 33258 staining and FCM. RESULTS: Rac1 siRNA can down-regulated the expression of Rac1 on human gastric cancer cell line SGC803 and colorectal cancer cell line Lovo remarkably, and Rac1 siRNA can inhibit both the proliferation and motility of the transfectants. Analysis of apoptosis demonstrated that Rac1 siRNA can promote apoptosis of the gastric cancer cells and colorectal cancer cells. CONCLUSION: Rac1 play an important role in the regulation of biological behaviors of human gastric cancer and colorectal cancer cells, and the interference of Rac1 expression could provide a novel path in reversing the malignant phenotypes of these malignancies.