Laminin-derived peptide C16 regulates Tks expression and reactive oxygen species generation in human prostate cancer cells.

Laminin peptides influence cancer biology. We investigated the role of a laminin-derived peptide C16 regulating invadopodia molecules in human prostate cancer cells (DU145). C16 augmented invadopodia activity of DU145 cells, and stimulated expression Tks4, Tks5, cortactin, and membrane-type matrix metalloproteinase 1. Reactive oxygen species generation is also related to invadopodia formation. This prompted us to address whether C16 would induce reactive oxygen species generation in DU145 cells. Quantitative fluorescence and flow cytometry showed that the peptide C16 increased reactive oxygen species in DU145 cells. Furthermore, significant colocalization between Tks5 and reactive oxygen species was observed in C16-treated cells. Results suggested that the peptide C16 increased Tks5 and reactive oxygen species in prostate cancer cells. The role of C16 increasing Tks and reactive oxygen species are novel findings on invadopodia activity.

Laminin-111 peptide C16 regulates invadopodia activity of malignant cells through ß1 integrin, Src and ERK 1/2.

Laminin peptides influence tumor behavior. In this study, we addressed whether laminin peptide C16 (KAFDITYVRLKF, γ1 chain) would increase invadopodia activity of cells from squamous cell carcinoma (CAL27) and fibrosarcoma (HT1080). We found that C16 stimulates invadopodia activity over time in both cell lines. Rhodamine-conjugated C16 decorates the edge of cells, suggesting a possible binding to membrane receptors. Flow cytometry showed that C16 increases activated ß1 integrin, and ß1 integrin miRNA-mediated depletion diminishes C16-induced invadopodia activity in both cell lines. C16 stimulates Src and ERK 1/2 phosphorylation, and ERK 1/2 inhibition decreases peptide-induced invadopodia activity. C16 also increases cortactin phosphorylation in both cells lines. Based on our findings, we propose that C16 regulates invadopodia activity over time of squamous carcinoma and fibrosarcoma cells, probably through ß1 integrin, Src and ERK 1/2 signaling pathways.

Integrative analysis to select cancer candidate biomarkers to targeted validation.

Targeted proteomics has flourished as the method of choice for prospecting for and validating potential candidate biomarkers in many diseases. However, challenges still remain due to the lack of standardized routines that can prioritize a limited number of proteins to be further validated in human samples. To help researchers identify candidate biomarkers that best characterize their samples under study, a well-designed integrative analysis pipeline, comprising MS-based discovery, feature selection methods, clustering techniques, bioinformatic analyses and targeted approaches was performed using discovery-based proteomic data from the secretomes of three classes of human cell lines (carcinoma, melanoma and non-cancerous). Three feature selection algorithms, namely, Beta-binomial, Nearest Shrunken Centroids (NSC), and Support Vector Machine-Recursive Features Elimination (SVM-RFE), indicated a panel of 137 candidate biomarkers for carcinoma and 271 for melanoma, which were differentially abundant between the tumor classes. We further tested the strength of the pipeline in selecting candidate biomarkers by immunoblotting, human tissue microarrays, label-free targeted MS and functional experiments. In conclusion, the proposed integrative analysis was able to pre-qualify and prioritize candidate biomarkers from discovery-based proteomics to targeted MS.