PYK2 mediates the BRAF inhibitor (vermurafenib)-induced invadopodia formation and metastasis in melanomas.

Junling Shen,Jilong Yang,Rui Sun,Weiyu Bai,Lei Sang,Chao Wang,Yan Sun,Jianwei Sun

doi:10.20892/j.issn.2095-3941.2020.0294

Abstract

Objective:The BRAF inhibitor, vemurafenib, has been widely used in the treatment of patients with melanoma-bearing BRAFV600E mutations. While the initial response to vemurafenib is usually excellent, the majority of patients eventually develop resistance and metastatic disease. However, the underlying molecular mechanism remains elusive. The objective of this study was therefore to identify additional molecular targets responsible for vemurafenib resistance.Methods:Western blots and immunohistochemistry analyses were used to evaluate expressions of PYK2 and p-PYK2 in cultured cells and melanoma tissue microarrays. The relationships of p-PYK2 with clinicopathological parameters were statistically analyzed. Invadopodia cell invasion, and a Ca2+ assay were used to determine the effect of vemurafenib resistance-induced p-PYK2 on melanoma progression. A mouse model was used to assess the effects of PYK2 on melanoma metastasis.Results:Elevated p-PYK2 levels were detected in vemurafenib-resistant melanoma cells, and PYK2 was shown to regulate invadopodia formation in melanoma cells. Vemurafenib triggered invadopodia formation by activation of PYK2. Inhibition of PYK2 with either shRNA or the small molecule inhibitor, PF562711, dramatically reduced vemurafenib-induced invadopodia formation. Furthermore, knockdown of PYK2 significantly reduced melanoma lung metastasis in vivo. Increased expressions of p-PYK2 in melanoma patients were positively correlated with advanced stage (P = 0.002), metastasis (P < 0.001), and Clark grade (P < 0.001), and were also associated with short overall survival [hazard ratio (HR) = 3.304, P = 0.007] and progression-free survival (HR = 2.930, P = 0.001).Conclusions:PYK2 mediated vemurafenib-induced melanoma cell migration and invasion. Inhibition of PYK2 resensitized melanoma cells to vemurafenib. Phospho-PYK2 was a prognostic biomarker in melanoma patients.

Highlights

Melanoma represents 10% of all skin cancers and is responsible for 80% of skin cancer-related deaths[1]
We found that the invasion ability of resistant cells was significantly reduced after removing vemurafenib from the medium (Figure 1A)
The results showed that the vemurafenib resistant cells had more invadopodia (Figure 1B and 1C)

Summary

Introduction

Melanoma represents 10% of all skin cancers and is responsible for 80% of skin cancer-related deaths[1]. Dacarbazin (DTIC), has been the traditional treatment for patients with advanced stage melanoma. DTIC treatment in melanoma patients has only a 10% response, with serious. Invadopodia are specialized, actin-rich membrane protrusions mediating focal extracellular matrix (ECM) degradation in malignant cancer cells[11,12,13]. Invadopodia assembly is initiated in response to the focal generation of phosphatidylinositol-3,4-biphosphate and activation of the non-receptor tyrosine kinase, Src, which recruits adaptor protein TKS5 and cortactin to assemble the actin core of invadopodium[14,15,16,17]. Invadopodia recruit and secrete proteinases such as membrane type 1- matrix metalloproteinase (MMP), MMP2, and MMP9 to degrade the ECM and facilitate invasion[15,16,17]. The role of PYK2 in melanoma invasion is not clear

Methods

Results

Conclusion