Elucidating the Functional Mechanism of PTK7 in Cancer Development through Spatial Assembly Analysis Using Super Resolution Imaging.

Protein tyrosine kinase-7 (PTK7) has been reported as a vital participant in the Wnt signaling pathway, influencing tumorigenesis and metastasis. However, their specific roles in the mechanisms underlying cancer development and progression remain elusive. Here, using direct stochastic optical reconstruction microscopy (dSTORM) with aptamer-probe labeling, we first revealed that a weakening clustering distribution of PTK7 on the basal membranes happened as cellular migration increased during cancer progression. This correspondence was further supported by a diminished aggregated state of PTK7 caused by direct enhancement of cell migration. By comparing the alterations in PTK7 distribution with activation or inhibition of specific Wnt signaling pathway, we speculated that PTK7 could modulate cell migration by participating in the interplay between canonical Wnt (in MCF7 cells) and noncanonical Wnt signals (in MDA-MB-231 cells). Furthermore, we discovered that the spatial distribution morphology of PTK7 was also subject to the hydrolysis ability and activation state of the related hydrolase Matrix metallopeptidase14 (MMP14). This function-related specific assembly of PTK7 reveals a clear relationship between PTK7 and cancer. Meanwhile, potential molecular interactions predicted by the apparent assembly morphology can promote a deep understanding of the functional mechanism of PTK7 in cancer progress.