Dro1/Ccdc80 inactivation promotes AOM/DSS-induced colorectal carcinogenesis and aggravates colitis by DSS in mice.

Colorectal carcinogenesis is a progressive multistep process involving the sequential accumulation of genetic alterations in tumor suppressor genes and oncogenes. Downregulated by oncogenes 1 (Dro1/Ccdc80) has been shown to be a potent tumor suppressor of colorectal carcinogenesis in the genetic ApcMin/+ mouse model. In ApcMin/+ mice, loss of DRO1 strongly increases colonic tumor multiplicity and leads to the regular formation of adenocarcinoma in the colon. To investigate DRO1's role in chemically induced as well as inflammation-associated colorectal carcinogenesis, the effect of Dro1 inactivation was studied in mice subjected to the carcinogen azoxymethane (AOM) and upon combined treatment with AOM and the proinflammatory agent dextran sodium sulfate (DSS), respectively. Loss of DRO1 increases multiplicity of preneoplastic aberrant crypt foci and colonic tumors upon administration of AOM. Combined treatment with AOM and DSS leads to increased colonic tumor number and promotes formation of adenocarcinoma in the colon. Moreover, Dro1 inactivation aggravates histological signs of acute and chronic DSS-induced colitis, strongly enlarges the size of ulcerative lesions in the intestinal lining, and exacerbates clinical signs and morbidity by DSS. Our results demonstrate DRO1 to be a strong tumor suppressor in the chemically induced colon carcinogenic mouse model. Additionally, we demonstrate DRO1 to inhibit colitis-associated colon cancer formation and uncover a novel putative role for DRO1 in inflammatory bowel disease.

Methylated free-circulating HPP1 DNA is an early response marker in patients with metastatic colorectal cancer.

Detection of methylated free-circulating DNA (mfcDNA) for hyperplastic polyposis 1 (HPP1) in blood is correlated with a poor prognosis for patients with metastatic colorectal cancers (mCRC). Here, we analyzed the plasma levels of HPP1 mfcDNA in mCRC patients treated with a combination therapy containing a fluoropyrimidine, oxaliplatin and bevacizumab to test whether HPP1 mfcDNA is a suitable prognostic and response biomarker. From 467 patients of the prospective clinical study AIO-KRK-0207, mfcDNA was isolated from plasma samples at different time points and bisulfite-treated mfcDNA was quantified using methylation specific PCR. About 337 of 467 patients had detectable levels for HPP1 mfcDNA before start of treatment. The detection was significantly correlated with poorer overall survival (OS) (HR = 1.86; 95%CI 1.37-2.53). About 2-3 weeks after the first administration of combination chemotherapy, HPP1 mfcDNA was reduced to non-detectable levels in 167 of 337 patients. These patients showed a better OS compared with patients with continued detection of HPP1 mfcDNA (HR HPP1(sample 1: pos/ sample 2: neg) vs. HPP1(neg/neg) = 1.41; 95%CI 1.00-2.01, HPP1(neg,pos/pos) vs. HPP1(neg/neg) = 2.60; 95%CI 1.86-3.64). Receiver operating characteristic analysis demonstrated that HPP1 mfcDNA discriminates well between patients who do (not) respond to therapy according to the radiological staging after 12 or 24 weeks (AUC = 0.77 or 0.71, respectively). Detection of HPP1 mfcDNA can be used as a prognostic marker and an early marker for response (as early as 3-4 weeks after start of treatment compared with radiological staging after 12 or 24 weeks) to identify patients who will likely benefit from a combination chemotherapy with bevacizumab.

γ-Catenin acts as a tumor suppressor through context-dependent mechanisms in colorectal cancer.

PURPOSE: γ-Catenin is a protein closely related to ß-catenin. While the overexpression of ß-catenin has been linked with impaired prognosis and survival in various malignancies, both oncogenic and tumor suppressor functions have been described for γ-catenin. Thus, its role in cancer remains controversial. In this study, we examined the impact of γ-catenin expression on the malignant potential of colorectal cancer cells. METHODS: γ-Catenin was knocked down by short interfering RNA in the γ-catenin-proficient DLD-1 cell line and stably overexpressed in the γ-catenin-deficient cell line RKO. The effects of these molecular manipulations on the malignant potential of the cell lines were tested in vitro and in vivo in a xenograft tumor model. RESULTS: γ-Catenin contributed to Wnt signaling independent of the cellular context. Unlike its sister molecule ß-catenin, γ-catenin inhibited cellular invasion and anoikis in cells endogenously expressing γ-catenin. In line with this tumor suppressor function, its de novo expression in RKO cells inhibited proliferation via cell cycle arrest. In a xenograft tumor model, overexpression of γ-catenin starkly reduced tumor growth in vivo. CONCLUSIONS: This is the first report demonstrating a tumor-suppressive effect of γ-catenin in colorectal cancer both in vitro and in vivo. Detailed in vitro analysis revealed that effects of γ-catenin differ in γ-catenin proficient and deficient cells, indicating that its function in colorectal cancer is dependent on the cellular context. This finding adds to our understanding of γ-catenin and may have implications for future studies of catenin/Wnt targeted cancer therapies.

ß-catenin regulates NF-κB activity via TNFRSF19 in colorectal cancer cells.

Wnt/ß-catenin signaling plays a crucial role in the regulation of colon tissue regeneration and the development of colon tumors. Under physiological conditions, ß-catenin activity is tightly controlled. However, the majority of sporadic forms of colorectal cancer are characterized by inactivation of the tumor suppressor gene APC due to loss of heterozygosity (LOH), resulting in deregulation of the protein ß-catenin. Apart from known ß-catenin target genes like MYC, OPG, and DKK4, the gene TNFRSF19, a member of the TNF receptor superfamily, is regulated by ß-catenin in mesenchymal stem cells (hMSC). We found that TNFRSF19 is frequently overexpressed in colorectal cancer cell lines and primary colorectal carcinomas. Further characterization revealed that both isoforms of TNFRSF19, TNFRSF19.1 and TNFRSF19.2, are regulated in a ß-catenin dependent manner. The transcript TNFRSF19.2 encodes a 417 amino acid long protein containing a TRAF-binding site that links the TNFRSF19.2 to NF-κB signaling, whereas the isoform TNFRSF19.1 lacks this TRAF-binding site. Nevertheless both isoform 1 and 2 induced the activity of an NF-κB reporter gene. NF-κB signaling is important for inflammatory processes and chronic inflammatory diseases like ulcerative colitis and Crohn's disease, which are associated with increased risk for developing colorectal cancer. The observation that TNFRSF19 is a ß-catenin target gene and TNFRSF19 receptor molecules activate NF-κB signaling shows that ß-catenin regulates NF-κB activity via TNFRSF19, suggesting that TNFRSF19 may contribute to the development of colorectal tumors with deregulated ß-catenin activity.

The inhibition of YAP Signaling Prevents Chronic Biliary Fibrosis in the Abcb4-/- Model by Modulation of Hepatic Stellate Cell and Bile Duct Epithelium Cell Pathophysiology.

Primary sclerosing cholangitis (PSC) represents a chronic liver disease characterized by poor prognosis and lacking causal treatment options. Yes-associated protein (YAP) functions as a critical mediator of fibrogenesis; however, its therapeutic potential in chronic biliary diseases such as PSC remains unestablished. The objective of this study is to elucidate the possible significance of YAP inhibition in biliary fibrosis by examining the pathophysiology of hepatic stellate cells (HSC) and biliary epithelial cells (BEC). Human liver tissue samples from PSC patients were analyzed to assess the expression of YAP/connective tissue growth factor (CTGF) relative to non-fibrotic control samples. The pathophysiological relevance of YAP/CTGF in HSC and BEC was investigated in primary human HSC (phHSC), LX-2, H69, and TFK-1 cell lines through siRNA or pharmacological inhibition utilizing verteporfin (VP) and metformin (MF). The Abcb4-/- mouse model was employed to evaluate the protective effects of pharmacological YAP inhibition. Hanging droplet and 3D matrigel culture techniques were utilized to investigate YAP expression and activation status of phHSC under various physical conditions. YAP/CTGF upregulation was observed in PSC patients. Silencing YAP/CTGF led to inhibition of phHSC activation and reduced contractility of LX-2 cells, as well as suppression of epithelial-mesenchymal transition (EMT) in H69 cells and proliferation of TFK-1 cells. Pharmacological inhibition of YAP mitigated chronic liver fibrosis in vivo and diminished ductular reaction and EMT. YAP expression in phHSC was effectively modulated by altering extracellular stiffness, highlighting YAP's role as a mechanotransducer. In conclusion, YAP regulates the activation of HSC and EMT in BEC, thereby functioning as a checkpoint of fibrogenesis in chronic cholestasis. Both VP and MF demonstrate effectiveness as YAP inhibitors, capable of inhibiting biliary fibrosis. These findings suggest that VP and MF warrant further investigation as potential therapeutic options for the treatment of PSC.

Cell-free circulating ALU repeats in serum have a prognostic value for colorectal cancer patients.

BACKGROUND: Carcinoembryonic antigen (CEA) is the only established serum biomarker for colorectal cancer (CRC). To facilitate therapy decisions and improve the overall survival of CRC patients, prognostic biomarkers are required. OBJECTIVE: We studied the prognostic value of five different cell free circulating DNA (fcDNA) fragments. The potential markers were ALU115, ALU247, LINE1-79, LINE1-300 and ND1-mt. METHODS: The copy numbers of the DNA fragments were measured in the peripheral blood serum of 268 CRC patients using qPCR, the results were compared to common and previously described markers. RESULTS: We found that ALU115 and ALU247 fcDNA levels correlate significantly with several clinicopathological parameters. An increased amount of ALU115 and ALU247 fcDNA fragments coincides with methylation of HPP1 (P< 0.001; P< 0.01), which proved to be a prognostic marker itself in former studies and also with increased CEA level (both P< 0.001). ALU115 and ALU247 can define patients with poor survival in UICC stage IV (ALU115: HR = 2.9; 95% Cl 1.8-4.8, P< 0.001; ALU247: HR = 2.2; 95% Cl 1.3-3.6; P= 0.001). Combining ALU115 and HPP1, the prognostic value in UICC stage IV is highly significant (P< 0.001). CONCLUSIONS: This study shows that an increased level of ALU fcDNA is an independent prognostic biomarker for advanced colorectal cancer disease.

Loss of DRO1/CCDC80 in the tumor microenvironment promotes carcinogenesis.

Tumors are composed of the tumor cells and the surrounding microenvironment. Both are closely interwoven and interact by a complex and multifaceted cross-talk which plays an integral part in tumor initiation, growth, and progression. Dro1/Ccdc80 has been shown to be a potent suppressor of colorectal cancer and ubiquitous inactivation of Dro1/Ccdc80 strongly promoted colorectal carcinogenesis in ApcMin/+ mice and in a chemically-induced colorectal cancer model. The aim of the present study was to investigate whether Dro1/Ccdc80's tumor suppressive function is tumor-cell-autonomous. Expression of Dro1/Ccdc80 in cancer cells had no effect on both colon tumor development in ApcMin/+ mice and formation of xenograft tumors. In contrast, DRO1/CCDC80 loss in the microenvironment strongly increased tumor growth in xenograft models, inhibited cancer cell apoptosis, and promoted intestinal epithelial cell migration. Moreover, stromal Dro1/Ccdc80 inactivation facilitated formation of intestinal epithelial organoids. Expression analyses showed Dro1/Ccdc80 to be significantly down-regulated in murine gastric cancer associated fibroblasts, in ApcMin/+ colon tumor primary stromal cells and in microdissected stroma from human colorectal cancer compared to normal, non-tumor stroma. Our results demonstrate epithelial derived DRO1/CCDC80 to be dispensable for intestinal tissue homeostasis and identify Dro1/Ccdc80 as tumor suppressor in the tumor microenvironment.

Comparative Response of HCC Cells to TKIs: Modified in vitro Testing and Descriptive Expression Analysis.

Introduction: Although the treatment paradigm for hepatocellular carcinoma (HCC) has recently shifted in favour of checkpoint inhibitor (CPI)-based treatment options, the tyrosine kinase inhibitors (TKI) currently approved for the treatment of HCC are expected to remain the cornerstone of HCC treatment alone or in combination with CPIs. Despite considerable research efforts, no biomarker capable of predicting the response to specific TKIs has been validated. Thus, personalized approaches to HCC may aid in determining optimal treatment lines for 2nd and 3rd lines. To identify new biomarkers, we examined differential sensitivity and investigated potential transcriptomic predictors. Methods: To this aim, the sensitivity of nine HCC cell lines to sorafenib, lenvatinib, regorafenib, and cabozantinib was evaluated by a prolonged treatment scheme to determine their respective growth rate inhibition concentrations (GR50). Subgroups discriminated by GR50 values underwent differential expression and gene set enrichment analysis (GSEA). Results: The nine cell lines showed broadly different sensitivities to different TKIs. GR50 values of sorafenib and regorafenib clustered closer in all cell lines, whereas treatments with lenvatinib and cabozantinib showed diversified GR50 values. GSEA showed the activation of specific pathways in sensitive vs non-sensitive cell lines. A signature consisting of 14 biomarkers (GAGE12H, GJB6, PTCHD3, PRH1-PRR4, C6orf222, HBB, C17orf99, GOLGA6A, CRYAA, CCL23, RP11-347C12.3, RP11-514O12.4, FAM180B, and TMPRSS4) discriminates the cell lines' response into three distinct treatment profiles: 1) equally sensible to sorafenib, regorafenib and cabozantinib, 2) sensible to lenvatinib, and 3) more sensible to regorafenib than sorafenib. Conclusion: We observed diverse responses to either of the four TKIs. Subgroup analysis of TKI effectiveness showed distinct transcriptomic profiles and signaling pathways associated with responsiveness. This prompts more extensive studies to explore and validate pharmacogenomic and transcriptomic strategies for a personalized treatment approach, particularly after the failure of CPI treatment.

p70 Ribosomal Protein S6 Kinase Is a Checkpoint of Human Hepatic Stellate Cell Activation and Liver Fibrosis in Mice.

BACKGROUND & AIMS: Progression of chronic liver disease (CLD) to liver cirrhosis and liver cancer is a major global cause of morbidity and mortality. Treatment options capable of inhibiting progression of liver fibrosis when etiological treatment of CLD is not available or fails have yet to be established. We investigated the role of serine/threonine kinase p70 ribosomal protein S6 kinase (p70S6K) as checkpoint of fibrogenesis in hepatic stellate cells (HSCs) and as target for the treatment of liver fibrosis. APPROACH & RESULTS: Immunohistochemistry was used to assess p70S6K expression in liver resection specimen. Primary human or murine HSCs from wild-type or p70S6K-/- mice as well as LX-2 cells were used for in vitro experiments. Specific small interfering RNA or CEP-1347 were used to silence or inhibit p70S6K and assess its functional relevance in viability, contraction and migration assays, fluorescence-activated cell sorting, and Western blot. These results were validated in vivo by a chemical model of fibrogenesis using wild-type and p70S6K-/- mice. Expression of p70S6K was significantly increased in human cirrhotic vs noncirrhotic liver-tissue and progressively increased in vitro through activation of primary human HSCs. Conversely, p70S6K induced fibrogenic activation of HSCs in different models, including the small interfering RNA-based silencing of p70S6K in HSC lines, experiments with p70S6K-/- cells, and the pharmacological inhibition of p70S6K by CEP-1347. These findings were validated in vivo as p70S6K-/- mice developed significantly less fibrosis upon exposure to CCl4. CONCLUSIONS: We establish p70S6K as a checkpoint of fibrogenesis in vitro and in vivo and CEP-1347 as potential treatment option that can safely be used for long-term treatment.

Methylation of NEUROG1 in serum is a sensitive marker for the detection of early colorectal cancer.

OBJECTIVES: Colorectal cancer is the third most common cancer and a major cause of cancer-related deaths. Early detection of colonic lesions can reduce the incidence and mortality of colorectal cancer. Colonoscopy is the screening test for colorectal cancer with the highest efficacy, but its acceptance in the general public is rather low. To identify suitable tumor-derived markers that could detect colorectal cancer in blood samples, we analyzed the methylation status of a panel of genes in sera of affected patients. METHODS: Using methylation-specific quantitative PCR, we analyzed the methylation of ten marker genes in sera of healthy individuals and patients with colorectal cancer. RESULTS: Only HLTF, HPP1/TPEF, and NEUROG1 DNA methylation was detectable in at least 50% of patients with colorectal cancers. Whereas HLTF and HPP1/TPEF preferentially detected advanced and metastasized colorectal cancers, NEUROG1 methylation was detectable in UICC stages I-IV at a similar rate. Compared with other methylation markers, such as ALX4, SEPT9, and vimentin, NEUROG1 shows a higher sensitivity for colorectal cancer at UICC stages I and II. At a specificity of 91%, NEUROG1 reached a sensitivity of 61% (confidence interval, 50.4-70.6%) for the detection of colorectal cancers. Furthermore, detection of NEUROG1 methylation was independent of age and gender. CONCLUSIONS: Methylation of the NEUROG1 gene is frequently found in sera of patients with colorectal cancers independent of tumor stage. The quantitative detection of NEUROG1 DNA methylation in serum is a suitable approach for the non-invasive screening for asymptomatic colorectal cancer.

Predictors of ribociclib-mediated antitumour effects in native and sorafenib-resistant human hepatocellular carcinoma cells.

PURPOSE: The cyclin-dependent kinases (CDKs) CDK4 and CDK6 are important regulators of the cell cycle and represent promising targets in cancer treatment. We aimed to investigate the relevance of CDK4/6 in the development of hepatocellular carcinoma (HCC) and the potential of ribociclib, a novel orally available CDK4/6 inhibitor, as a treatment for HCC. METHODS: The effect of ribociclib was assessed in native and sorafenib-resistant HCC cell lines using viability assays, colony formation assays and FACS-based analyses. The expression of potential biomarkers of ribociclib response was assessed in cell lines and primary human hepatocytes using Western blotting. In addition, the prognostic relevance of the cyclin D-CDK4/6-retinoblastoma protein (Rb) pathway was assessed by analysing mRNA expression data from The Cancer Genome Atlas (TCGA). RESULTS: We found that ribociclib downregulated Rb and caused a profound loss of cell viability by inducing G1 cell cycle arrest in HCC cell lines exhibiting Rb-high/p16-low protein expression profiles, but not in Rb-low/p16-high cells, regardless their sensitivity to sorafenib. siRNA-based Rb silencing decreased cell proliferation, but did not diminish the sensitivity of HCC cells to ribociclib. Furthermore, we found that ribociclib synergized with sorafenib to cause cell death. mRNA analysis of primary human HCC specimens showed that CDK4 expression was correlated with patient survival and that the expression of Rb and the p16-encoding CDKN2A gene were inversely correlated. CONCLUSIONS: From our data we conclude that impairment of the cyclin D-CDK4/6-Rb pathway is a frequent feature of HCC and that it is associated with a unfavourable prognosis. We also found that ribociclib exhibits a preferential antineoplastic activity in Rb-high HCC cells. Our results warrant further investigation of Rb and p16 expression as markers of HCC sensitivity to ribociclib.

Loss of DRO1/CCDC80 results in obesity and promotes adipocyte differentiation.

To investigate the role of DRO1 in obesity and adipogenesis in vivo, we generated a constitutive Dro1 knockout mouse model and analyzed the effect of DRO1 loss on body growth under standard and high fat diet feeding conditions. Loss of DRO1 resulted in a significant increase in body weight which was accompanied by a substantial expansion of white adipose tissue depots. The obese phenotype could be further enhanced by a high fat dietary challenge which also resulted in impaired glucose metabolism and the development of hepatosteatosis in Dro1 knockout mice. To study the role of DRO1 in adipocyte differentiation, primary stromal-vascular (SV) cells were isolated from inguinal white fat pads of knockout and control mice. In primary SV cells, depletion of DRO1 significantly promoted adipogenesis with upregulation of markers for adipogenesis (Cebpa, Pparg, Adipoq) and lipid metabolism (Dgat1, Dgat2). Our results demonstrate that DRO1 is a crucial regulator of energy homeostasis in vivo and functions as an inhibitor of adipogenesis in primary cells.

The FGFR Inhibitor NVP-BGJ398 Induces NSCLC Cell Death by Activating Caspase-dependent Pathways as well as Caspase-independent Apoptosis.

BACKGROUND: Fibroblast growth factor receptors are expressed in diverse cell types. They play a critical role in tumor development. Their activation promotes cell-cycle progression, angiogenesis, and cell survival by induction/suppression of the expression of proteins involved. MATERIALS AND METHODS: Non-small cell lung cancer (NSCLC) cells (line H1581) were treated with NVP-BGJ398 to evaluate effects on growth by western blot, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide assay and cell-cycle analysis. RESULTS: NVP-BGJ398 induced cell death in H1581 cells by activating caspase-dependent mitochondrial and non-mitochondrial pathways. Caspase-independent apoptosis was also activated. Cells were found to be arrested in the G0/G1 phase. Furthermore, the expression of the tumor-suppressor gene programmed cell death 4 (PDCD4) was up-regulated with suppression of angiopoietin 2 (ANG2). This represents an additional mechanism by which NVP-BGJ389 inhibits tumor growth. CONCLUSION: Various pathways induce apoptosis in NSCLC cells by employing NVP-BGJ398. These data reflect the potential of cancer treatment utilizing small FGFR inhibitors.

DRO1 inactivation drives colorectal carcinogenesis in ApcMin/+ mice.

UNLABELLED: Colorectal cancer develops from adenomatous precursor lesions by a multistep process that involves several independent mutational events in oncogenes and tumor suppressor genes. Inactivation of the adenomatous polyposis coli (APC) tumor suppressor gene is an early event and a prerequisite for the development of human colorectal adenoma. Previous in vitro studies identified DRO1 (CCDC80) to be a putative tumor suppressor gene that is negatively regulated in colorectal cancers and downregulated upon neoplastic transformation of epithelial cells. To investigate the in vivo role of DRO1 in colorectal carcinogenesis, a constitutive DRO1 knockout mouse model was generated. Disruption of DRO1 did not result in spontaneous intestinal tumor formation, consistent with the notion that DRO1 might have a role in suppressing the development of colon tumors in Apc(Min) (/+) mice, a widely used model for studying the role of APC in intestinal tumorigenesis that is hampered by the fact that mice predominantly develop adenomas in the small intestine and not in the colon. Here, deletion of DRO1 in Apc(Min) (/+) mice results in earlier death, a dramatically increased colonic tumor burden, and frequent development of colorectal carcinoma. Furthermore, enhanced phosphorylation of ERK1/2 is observed in colon epithelium and tumors from DRO1 knockout mice. Thus, this study reveals that inactivation of DRO1 is required for colorectal carcinogenesis in the Apc(Min) (/+) mouse and establishes a new mouse model for the study of colorectal cancer. IMPLICATIONS: This report characterizes a new mouse model for the study of colorectal cancer and establishes DRO1 (CCDC80) as a tumor suppressor via a mechanism involving ERK phosphorylation.