Doublecortin-like kinase1 (DCLK1), a microtubule associated protein (MAP), has recently gained interest in the cancer research field. Whole-genome sequencing suggests that DCLK1 is a novel tumour driver and DCLK1 overexpression correlates with epithelial-to-mesenchymal transition (EMT) in pancreas, intestine and colon cancer. A recent meta-analysis in gastric cancer (GC) showed that DCLK1 overexpression correlates with advanced and poorly differentiated GC, lymph node metastasis and reduced overall patient survival.
Our analysis of the stomach adenomas (STAD) dataset from the Cancer Genome Atlas (TCGA), showed that DCLK1-high expressing tumours significantly clustered within the genomic stable molecular subtype and the histologically diffuse type. We are currently evaluating DCLK1 expression off 300 stomach cancer patients by immunohistochemistry on tissue microarrays.
We established a DCLK1-overexpressing MKN1 gastric cancer cell-line. The overexpression resulted in increased migration and invasion in vitro and in vivo. These findings support our TCGA-STAD data analysis where high DCLK1 levels correlated with EMT, chemokines, and stromal- and immune cell markers. Strikingly, we observed an overall increase in chemokine secretion when DCLK1 is overexpressed, ex vivo. CXCL12 is the one of the main upregulated chemokines; this is further supported by findings in the TCGA-STAD data set, which shows that DCLK1 and CXCL12 expression levels significantly correlate with each other. Furthermore, a DCLK1-inhibitor reversed migration, invasion and chemokine secretion in the DCLK1-overexpressing MKN1 cells to parental MKN1 cell levels, in vitro and in vivo. This suggests that DCLK1 could be a good target for poor prognosis GCs with high DCLK1 levels.
Thus far, the signalling cascade in which DCLK1 can induce EMT or increased chemokine secretion is poorly understood. Our aim is to answer these questions using SILAC mass spectrometry studies by comparing proteomics, phospho-proteomics and secretomics analysis on parental MKN1 and DCLK1-overexpressing MKN1 cells, with and without DCLK1-inhibitor.