Inhibition of Liver Metastasis in Colorectal Cancer by Targeting IL-13/IL13Rα2 Binding Site with Specific Monoclonal Antibodies.

BACKGROUND: IL13Rα2 is reportedly a promising therapeutic target in different cancers. Still, no specific antagonists have reached the clinics yet. We investigated the use of a IL-13/IL13Rα2 binding motif, called D1, as a new target for the development of therapeutic monoclonal antibodies (mAbs) for colorectal cancer (CRC) metastasis. METHODS: IL13Rα2 D1 peptides were prepared and used for immunization and antibody development. Antibodies were tested for inhibition of cellular invasion through Matrigel using CRC cell lines. Effects of the mAbs on cell signaling, receptor internalization and degradation were determined by western blot and flow cytometry. Swiss nude mice were used for survival analysis after treatment with IL13Rα2-specific mAbs and metastasis development. RESULTS: IL13Rα2 D1 peptides were used to generate highly selective mAbs that blocked IL13/IL13Rα2-mediated SRC activation and cell invasion in colorectal cancer cells. Antibodies also provoked a significant reduction in cell adhesion and proliferation of metastatic cancer cells. Treatment with mAbs impaired the FAK, SRC and PI3K/AKT pathway activation. Blocking effectivity was shown to correlate with the cellular IL13Rα2 expression level. Despite mAb 5.5.4 partially blocked IL-13 mediated receptor internalization from the cancer cell surface it still promotes receptor degradation. Compared with other IL13Rα2-specific antibodies, 5.5.4 exhibited a superior efficacy to inhibit metastatic growth in vivo, providing a complete mouse survival in different conditions, including established metastasis. CONCLUSIONS: Monoclonal antibody 5.5.4 showed a highly selective blocking capacity for the interaction between IL-13 and IL13Rα2 and caused a complete inhibition of liver metastasis in IL13Rα2-positive colorectal cancer cells. This capacity might be potentially applicable to other IL13Rα2-expressing tumors.

A label-free nanostructured plasmonic biosensor based on Blu-ray discs with integrated microfluidics for sensitive biodetection.

Nanostructure-based plasmonic biosensors have quickly positioned themselves as interesting candidates for the design of portable optical biosensor platforms considering the potential benefits they can offer in integration, miniaturization, multiplexing, and real-time label-free detection. We have developed a simple integrated nanoplasmonic sensor taking advantage of the periodic nanostructured array of commercial Blu-ray discs. Sensors with two gold film thicknesses (50 and 100nm) were fabricated and optically characterized by varying the oblique-angle of the incident light in optical reflectance measurements. Contrary to the use normal light incidence previously reported with other optical discs, we observed an enhancement in sensitivity and a narrowing of the resonant linewidths as the light incidence angle was increased, which could be related to the generation of Fano resonant modes. The new sensors achieve a figure of merit (FOM) up to 35 RIU-1 and a competitive bulk limit of detection (LOD) of 6.3×10-6 RIU. These values significantly improve previously reported results obtained with normal light incidence reflectance measurements using similar structures. The sensor has been combined with versatile, simple, ease to-fabricate microfluidics. The integrated chip is only 1cm2 (including a PDMS flow cell with a 50µm height microfluidic channel fabricated with double-sided adhesive tape) and all the optical components are mounted on a 10cm×10cm portable prototype, illustrating its facile miniaturization, integration and potential portability. Finally, to assess the label-free biosensing capability of the new sensor, we have evaluated the presence of specific antibodies against the GTF2b protein, a tumor-associate antigen (TAA) related to colorectal cancer. We have achieved a LOD in the pM order and have assessed the feasibility of directly measuring biological samples such as human serum.

An RGD motif present in cadherin 17 induces integrin activation and tumor growth.

Little is known about the mechanism of integrin activation by cadherin 17 (CDH17). Here we observed the presence of a tri-peptide motif, RGD, in domain 6 of the human CDH17 sequence and other cadherins such as cadherin 5 and cadherin 6. The use of CDH17 RAD mutants demonstrated a considerable decrease of proliferation and adhesion in RKO and KM12SM colon cancer cells. Furthermore, RGD peptides inhibited the adhesion of both cell lines to recombinant CDH17 domain 6. The RGD motif added exogenously to the cells provoked a change in ß1 integrin to an active, high-affinity conformation and an increase in focal adhesion kinase and ERK1/2 activation. In vivo experiments with Swiss nude mice demonstrated that cancer cells expressing the CDH17 RAD mutant showed a considerable delay in tumor growth and liver homing. CDH17 RGD effects were also active in pancreatic cancer cells. Our results suggest that α2ß1 integrin interacts with two different ligands, collagen IV and CDH17, using two different binding sites. In summary, the RGD binding motif constitutes a switch for integrin pathway activation and shows a novel capacity of CDH17 as an integrin ligand. This motif could be targeted to avoid metastatic dissemination in tumors overexpressing CDH17 and other RGD-containing cadherins.