Co-migration of colon cancer cells and CAFs induced by TGFß1 enhances liver metastasis.

Colorectal cancer (CRC) cells often metastatize to the liver. Cancer-associated fibroblasts (CAFs) enhance metastasis by providing cytokines that create a favorable microenvironment and by inducing co-dissemination with tumor cells. However, the mechanisms of co-metastatization remain elusive. The aim of this study is to assess the role of TGFß1 in CRC cell-CAFs attachment and its impact on liver metastasis. CAFs were obtained after xenotransplantation of Mc38 cells into EGFP-C57BL/6 mice. Attachment experiments with CRC cells and CAFs (with or without TGFß1 and the inhibitory peptide P17) were carried out, as well as in vivo liver metastasis assays. TGFß1 induced adhesion of CRC cells to CAFs, whereas exposure to P17 abrogated this effect. Co-injection of Mc38 cells with CAFs intrasplenically increased liver metastasis, as compared to injection of tumor cells alone. Pretreatment of Mc38 cells with TGFß1 enhanced the metastatic burden, in comparison to untreated Mc38 + CAFs. TGFß1-pretreated Mc38 cells co-metastatized with CAFs to the liver in a highly efficient way. Importantly, the metastatic burden was significantly reduced (p < 0.001) when P17 was administered in mice. The number of PCNA+ and CD-31+ cells was also reduced by P17 in these animals, indicating a decrease in proliferation and angiogenesis upon TGFß1 signaling blockade. Through microarray analysis, we identified potential TGFß1-regulated genes that may mediate cancer cell-stroma interactions to increase metastasis. In conclusion, TGFß1 promotes co-travelling of CRC cells and CAFs to the liver to enhance metastasis. Our results strongly support the use of TGFß1 targeted drugs as a novel strategy to reduce liver metastasis in CRC patients.

Targeting of TMPRSS4 sensitizes lung cancer cells to chemotherapy by impairing the proliferation machinery.

High mortality rates caused by NSCLC show the need for the identification of novel therapeutic targets. In this study we have investigated the biological effects and molecular mechanisms elicited by TMPRSS4 in NSCLC. Overexpression of TMPRSS4 in LKR13 cells increased malignancy, subcutaneous tumor growth and multiorganic metastasis. In conditional knock-down (KD) experiments, abrogation of TMPRSS4 in H358 and H2170 cells altered proliferation, clonogenicity, tumor engraftment and tumor growth. Reduction in S and G2/M phases of the cell cycle, decreased BrdU incorporation and increased apoptosis was also found. Transcriptomic analysis in KD cells revealed downregulation of genes involved in DNA replication, such as MCM6, TYMS and CDKN1A (p21). In patients, expression of a signature of MCM6/TYMS/TMPRSS4 genes was highly associated with poor prognosis. Downregulation of TMPRSS4 significantly increased sensitivity to chemotherapy agents. In experiments using cisplatin, apoptosis and expression of the DNA-damage marker γ-H2A was higher in cells lacking TMPRSS4. Moreover, in vivo assays demonstrated that tumors with no TMPRSS4 were significantly more sensitive to cisplatin than controls. These results show that TMPRSS4 can be considered as a novel target in NSCLC, whose inhibition increases chemosensitivity.

miR-146a targets c-met and abolishes colorectal cancer liver metastasis.

A major complication of colorectal cancer (CRC), one of the most frequent and deadly types of cancer, is disease progression via liver metastases. At this stage, very few treatment options are available for patients, and the disease remains incurable. Herein, we used a well-established mouse model of CRC liver metastasis (CLM) to identify new regulators of this process. Using serial transplantation of murine MC38 adenocarcinoma cells, we obtained liver metastatic variants that displayed extremely strong colonization abilities. Using these newly established cell lines, we performed gene expression arrays and microRNA (miR) profiling. Comparative and predictive analyses between the two arrays showed higher expression of c-met and concomitant reduction of miR-146a in the mestastatic variants. In CRC patients, expression levels of both c-met and miR-146a were similar between primary tumors and liver metastases. Interestingly, we identified c-met as a new target for miR-146a, as miR-146a was able to impede c-met translation. Of relevance, overexpression of miR-146a in metastatic clones showed reduced in vitro malignancy and abolished the development of primary tumor and liver metastases. Our results document a new mechanism for c-met regulation in CLM and highlight the crucial role of miR-146a in suppressing tumorigenesis.

Development of biological tools to assess the role of TMPRSS4 and identification of novel tumor types with high expression of this prometastatic protein.

Metastatic spread is responsible for the majority of cancer deaths and identification of metastasis-related therapeutic targets is compulsory. TMPRSS4 is a pro-metastatic druggable transmembrane type II serine protease whose expression has been associated with the development of several cancer types and poor prognosis. To study the role and expression of this protease in cancer, we have developed molecular tools (active recombinant proteins and a polyclonal antibody) that can be used for diagnostic purposes and for testing anti-TMPRSS4 drugs. In addition, we have evaluated TMPRSS4 protein expression in several cancer tissue microarrays (TMAs). Full length and truncated TMPRSS4 recombinant proteins maintained the catalytic activity in two different expression systems (baculovirus and E. coli). Sensitivity of the rabbit polyclonal antisera against TMPRSS4 (ING-pAb) outperformed the antibody most commonly used in clinical settings. Analysis by immunohistochemistry in the different TMAs identified a subset of adenocarcinomas, squamous carcinomas, large cell carcinomas and carcinoids of the lung, which may define aggressive tumors. In conclusion, our biological tools will help the characterization of TMPRSS4 activity and protein expression, as well as the evaluation of anti-TMRSS4 drugs. Future studies should determine the clinical value of assessing TMPRSS4 levels in different types of lung cancer.

Epigenetic alterations leading to TMPRSS4 promoter hypomethylation and protein overexpression predict poor prognosis in squamous lung cancer patients.

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related death worldwide, which highlights the need of innovative therapeutic options. Although targeted therapies can be successfully used in a subset of patients with lung adenocarcinomas (ADC), they are not appropriate for patients with squamous cell carcinomas (SCC). In addition, there is an unmet need for the identification of prognostic biomarkers that can select patients at risk of relapse in early stages. Here, we have used several cohorts of NSCLC patients to analyze the prognostic value of both protein expression and DNA promoter methylation status of the prometastatic serine protease TMPRSS4. Moreover, expression and promoter methylation was evaluated in a panel of 46 lung cancer cell lines. We have demonstrated that a high TMPRSS4 expression is an independent prognostic factor in SCC. Similarly, aberrant hypomethylation in tumors, which correlates with high TMPRSS4 expression, is an independent prognostic predictor in SCC. The inverse correlation between expression and methylation status was also observed in cell lines. In vitro studies showed that treatment of cells lacking TMPRSS4 expression with a demethylating agent significantly increased TMPRSS4 levels. In conclusion, TMPRSS4 is a novel independent prognostic biomarker regulated by epigenetic changes in SCC and a potential therapeutic target in this tumor type, where targeted therapy is still underdeveloped.

TMPRSS4 induces cancer stem cell-like properties in lung cancer cells and correlates with ALDH expression in NSCLC patients.

Metastasis involves a series of changes in cancer cells that promote their escape from the primary tumor and colonization to a new organ. This process is related to the transition from an epithelial to a mesenchymal phenotype (EMT). Recently, some authors have shown that migratory cells with an EMT phenotype share properties of cancer stem cells (CSCs), which allow them to form a new tumor mass. The type II transmembrane serine protease TMPRSS4 is highly expressed in some solid tumors, promotes metastasis and confers EMT features to cancer cells. We hypothesized that TMPRSS4 could also provide CSC properties. Overexpression of TMPRSS4 reduces E-cadherin and induces N-cadherin and vimentin in A549 lung cancer cells, supporting an EMT phenotype. These changes are accompanied by enhanced migration, invasion and tumorigenicity in vivo. TMPRSS4 expression was highly increased in a panel of lung cancer cells cultured as tumorspheres (a typical assay to enrich for CSCs). H358 and H441 cells with knocked-down TMPRSS4 levels were significantly less able to form primary and secondary tumorspheres than control cells. Moreover, they showed a lower proportion of ALDH+ cells (examined by FACS analysis) and lower expression of some CSC markers than controls. A549 cells overexpressing TMPRSS4 conferred the opposite phenotype and were also more sensitive to the CSC-targeted drug salinomycin than control cells, but were more resistant to regular chemotherapeutic drugs (cisplatin, gemcitabine and 5-fluorouracil). Analysis of 70 NSCLC samples from patients revealed a very significant correlation between TMPRSS4 expression and CSC markers ALDH (p = 0.0018) and OCT4 (p = 0.0004), suggesting that TMPRSS4 is associated with a CSC phenotype in patients' tumors. These results show that TMPRSS4, in addition to inducing EMT, can also promote CSC features in lung cancer; therefore, CSC-targeting drugs could be an appropriate treatment for TMPRSS4+ tumors.