Search

The transcription factor Twist1 is involved in the epithelial–mesenchymal transition and contributes to cancer metastasis through mostly unknown mechanisms. In colorectal cancer, Twist1 expression is mainly restricted to the tumor stroma. We found that human fibroblast cell lines stably transfected with Twist1 acquired characteristics of activated cancer-associated fibroblasts (CAFs), such as hyperproliferation, an increased ability to migrate and an alignment of the actin cytoskeleton. Further, Twist1-activated fibroblasts promoted increased matrix stiffness. Using quantitative proteomics, we identified palladin and collagen α1(VI) as two major mediators of the Twist1 effects in fibroblast cell lines. Co-immunoprecipitation studies indicated that palladin and Twist1 interact within the nucleus, suggesting that palladin could act as a transcription regulator. Palladin was found to be more relevant for the cellular biomechanical properties, orientation and polarity, and collagen α1(VI) for the migration and invasion capacity, of Twist1-activated fibroblasts. Both palladin and collagen α1(VI) were observed to be overexpressed in colorectal CAFs and to be associated with poor colorectal cancer patient survival and relapse prediction. Our results demonstrate that Twist1-expressing fibroblasts mimic the properties of CAFs present at the tumor invasive front, which likely explains the prometastatic activities of Twist1. Twist1 appears to require both palladin and collagen α1(VI) as downstream effectors for its prometastatic effects, which could be future therapeutic targets in cancer metastasis., IG-P was supported by a contract S2010/BMD-2344/ Colomics2 from the Comunidad de Madrid. ST was a recipient of a Juan de la Cierva programme. RAB was supported by a grant to established research groups of the Asociación Española Contra el Cáncer (AECC). ML-L was a recipient of a ProteoRed contract. AP-G and BE-P were FPI fellows from the Ministry of Economy and Competitiveness (MINECO). This research was supported by grants to established research groups of the S2010/BMD-2344/Colomics2 from the Comunidad de Madrid, ‘Asociación Española Contra el Cancer (AECC)’, BIO2012-31023 from the MINECO, PRB2 (IPT13/0001-ISCIII-SGEFI/FEDER), RD12/0036/0041 and RD12/0036/0021 from the Instituto de Salud Carlos III-FEDER.

37 p.-6 fig., Pancreatic adenocarcinoma–upregulated factor (PAUF), also known as ZG16B, was previously found in the secretome of metastatic colorectal cancer cells. Here, we demonstrated the presence of PAUF at the intracellular level and its multiple effects on cancer progression. An initial decline of PAUF expression was observed at early stages of colorectal cancer followed by an increase at the metastastic site. PAUF was located at different cellular compartments: membrane-associated vesicles, endosomes, microtubule-associated vesicles, cell growth cones and the cell nucleus. PAUF loss in two colorectal cancer cell lines caused severe alterations in the cell phenotype and cell cycle, including tetraploidy, extensive genomic alterations, micronuclei, and increased apoptosis. An exhaustive analysis of the PAUF interactome using different proteomic approaches revealed the presence of multiple components of the cell cycle, mitotic checkpoint, Wnt pathway and intracellular transport. Among the interacting proteins we found ZW10, a moonlighting protein with a dual function in membrane trafficking and mitosis. In addition, PAUF silencing was associated to APC loss and increased β-catenin nuclear expression. Altogether, our results suggest that PAUF depletion increases aneuploidy, promotes apoptosis and activates the Wnt/β-catenin pathway in colorectal cancer cells facilitating cancer progression. In summary, PAUF behaves as a multifunctional protein, with different roles in cancer progression according to the extra- or intracellular expression, suggesting a therapeutic value for colorectal cancer., This research was supported by grants from the MINECO (BIO2015-66489-R), Fundación Areces and PRB3 (IPT17/0019 - ISCIII-SGEFI /ERDF).

13 p.-6 fig., We have investigated the role of vascular-endothelial (VE)-cadherin in melanoma and breast cancer metastasis. We found that VE-cadherin is expressed in highly aggressive melanoma and breast cancer cell lines. Remarkably, inactivation of VEcadherin triggered a significant loss of malignant traits (proliferation, adhesion, invasion and transendothelial migration) in melanoma and breast cancer cells. These effects, except transendothelial migration, were induced by the VE-cadherin RGD motifs. Co-immunoprecipitation experiments demonstrated an interaction between VE-cadherin and α2β1 integrin, with the RGD motifs found to directly affect β1 integrin activation. VE-cadherin-mediated integrin signaling occurred through specific activation of SRC, ERK and JNK, including AKT in melanoma. Knocking down VEcadherin suppressed lung colonization capacity of melanoma or breast cancer cells inoculated in mice, while pre-incubation with VE-cadherin RGD peptides promoted lung metastasis for both cancer types. Finally, an in silico study revealed the association of high VE-cadherin expression with poor survival in a subset of melanoma patients and breast cancer patients showing low CD34 expression. These findings support a general role for VE-cadherin and other RGD cadherins as critical regulators of lung and liver metastasis in multiple solid tumours. These results pave the way for cadherin-specific RGD targeted therapies to control disseminated metastasis in multiple cancers., BEP was an FPI fellow from Ministry of Economy and Competitiveness (MINECO). This research was supported by grants BIO2012-31023 and BIO2015-66849 from MINECO and PRB2 (IPT13/0001-ISCIII-SGEFI/FEDER) to JIC.

Most colorectal cancer deaths occur as a consequence of late diagnosis and the appearance of metastasis. We demonstrated that a RGD motif present in liver-intestine cadherin, also known as cadherin 17 (CDH17), plays a critical role in the liver metastasis of colorectal cancer by interacting with α2β1 integrin. CDH17 is able to induce a conformational change in β1 integrin to promote a high affinity conformation. This change is dependent of the RGD motif present in domain 6 of CDH17. The same activation was observed after cell exposition to 9 amino acid peptides containing the RGD motif and the flanking sequences from CDH17. Commercial antibodies anti-CDH17 did not cause any effect on β1 integrin activation. Here, we have used peptides containing the RGD motif and their flanking sequences in CDH17 to retrieve four highly selective monoclonal antibodies with anti-metastatic activity. Only CDH17 RGD-specific monoclonal antibodies inhibited β1 integrin activation in colorectal cancer cells. This inhibition provoked a significant reduction in cell adhesion and proliferation of metastatic cells. In addition, the treatment with these four anti-cadherin RGD antibodies impaired the activation of FAK, JNK and ERK kinases, which are critical for cell adhesion and proliferation. Moreover, RGD-specific monoclonal antibodies were able to cause a significant increase in mouse survival after intra-splenic injection together with highly metastatic cells, as determined by Kaplan-Meier survival analysis and log-rank curves. However, this effect on survival was different for each monoclonal antibody, suggesting a relevant impact of the RGD binding orientation in antibody recognition. As a conclusion, we propose that blocking the interaction between RGD cadherins and α2β1 integrin with highly selective monoclonal antibodies constitutes a promising therapy against colon cancer progression and liver metastasis. Citation Format: Rubén Bartolomé, Sofia Torres, Beatriz Escudero-Paniagua, Carmen Aizpurua, Eva Calviño, Juan I. Imbaud, Ignacio Casal. Anti-metastatic activity of RGD-specific cadherin-17-targeting monoclonal antibodies in colorectal cancer. [abstract]. In: Proceedings of the AACR Special Conference on Colorectal Cancer: From Initiation to Outcomes; 2016 Sep 17-20; Tampa, FL. Philadelphia (PA): AACR; Cancer Res 2017;77(3 Suppl):Abstract nr B15.