Multiomics characterization implicates PTK7 in ovarian cancer EMT and cell plasticity and offers strategies for therapeutic intervention

Abstract

Most patients with ovarian cancer (OC) are diagnosed at a late stage when there are very few therapeutic options and a poor prognosis. This is due to the lack of clearly defined underlying mechanisms or an oncogenic addiction that can be targeted pharmacologically, unlike other types of cancer. Here, we identified protein tyrosine kinase 7 (PTK7) as a potential new therapeutic target in OC following a multiomics approach using genetic and pharmacological interventions. We performed proteomics analyses upon PTK7 knockdown in OC cells and identified novel downstream effectors such as synuclein-γ (SNCG), SALL2, and PP1γ, and these findings were corroborated in ex vivo primary samples using PTK7 monoclonal antibody cofetuzumab. Our phosphoproteomics analyses demonstrated that PTK7 modulates cell adhesion and Rho-GTPase signaling to sustain epithelial-mesenchymal transition (EMT) and cell plasticity, which was confirmed by high-content image analysis of 3D models. Furthermore, using high-throughput drug sensitivity testing (525 drugs) we show that targeting PTK7 exhibited synergistic activity with chemotherapeutic agent paclitaxel, CHK1/2 inhibitor prexasertib, and PLK1 inhibitor GSK461364, among others, in OC cells and ex vivo primary samples. Taken together, our study provides unique insight into the function of PTK7, which helps to define its role in mediating aberrant Wnt signaling in ovarian cancer.

Knockdown of PTK7 Reduces the Oncogenic Potential of Breast Cancer Cells by Impeding Receptor Tyrosine Kinase Signaling

“…Epithelial-mesenchymal transition (EMT) is widely recognized as a crucial process in cancer cell migration and invasion [37]. Moreover, the involvement of PTK7 in EMT has been reported in hepatocellular carcinoma [38] and ovarian cancer [39]. Based on these findings, we hypothesized that PTK7 may also play a role in the migration and invasion of BC cells through EMT.…”

Recent insights into the therapeutic strategies targeting the pseudokinase PTK7 in cancer

“…This heterotrimeric complex is conserved in Xenopus where it regulates protocadherin papc expression and embryonic development [ 29 ]. However, it signals differently in other cellular systems such as pro-B cells [ 40 ] or ovarian cancer (OVCA) cells where PTK7 modulates cell adhesion and Rho-GTPase signaling to sustain epithelial-mesenchymal transition and cell plasticity [ 41 ].…”

“…adhesion and Rho-GTPase signaling to sustain epithelialmesenchymal transition and cell plasticity [41].…”

Identification of the Binding Site between Aptamer sgc8c and PTK7

“…After a cell-specific aptamer is obtained, the aptamer target on the cell membrane can be identified in reverse. For example, the aptamer sgc8c screened by our group has been proven to effectively bind with target CEM cells instead of nontarget Ramos cells, and the membrane target has been identified to be protein tyrosine kinase 7 (PTK7), also known as colon cancer kinase 4 (CCK4). , PTK7 is thought to be expressed in colon cancer but not in the normal colon and thus may be a biomarker of tumor progression or possibly involved in tumor progression. − PTK7 functions as a context-dependent signaling switch of the Wnt pathway (especially in planar cells, polarity-related functions such as convergent elongation and neural crest cell migration). − PTK7 is a single transmembrane protein whose cytoplasmic kinase structure has no evidence of kinase activity, and the extracellular domain contains seven immunoglobulin-like folds. , In spite of the wide applications of sgc8c, − the accurate binding site between the aptamer and the target is still not clear because the detailed binding mode between the aptamer and the target cannot be characterized during a typical SELEX process. Herein, we implemented a series of experiments to characterize the detailed interaction region between sgc8c and PTK7.…”