Abstract
BackgroundImplantation metastasis is the main means of dissemination in ovarian cancer. Our previous studies showed that SET and MYND domain-containing protein 3 (SMYD3) expression was higher in ovarian cancer spheroids than in monolayers. SMYD3 enhancement of spheroid invasion and adhesion is mediated by the downstream effectors ITGB6 and ITGAM. However, the potential mechanisms underlying the SMYD3/integrin-mediated invasion and adhesion of spheroids still need to be explored.MethodsWestern blotting was used to examine the expression of SMYD3, ITGB6 and downstream molecules under different treatments. Immunofluorescence was used to detect the expression of F-actin, E-cadherin and N-cadherin. Anti-ITGB6 antibody-based inhibition and dual-luciferase reporter assays were used to confirm the binding between ITGB6 and latent TGFβ1. Transwell invasion, adherence and 3D tumor spheroid invasion assays were employed to test the effects of TGFβ1 on the invasion and adhesion of ovarian cancer spheroids. ELISA was performed to assess the release of latent TGFβ1 from ovarian cancer spheroids.ResultsSMYD3 and ITGB6 activated the TGFβ1/Smad3 pathway and then induced the upregulation of Snail, Vimentin and N-cadherin and the downregulation of E-cadherin in 3D-cultured ovarian cancer spheroids. In this process, latent TGFβ1 could bind to ITGB6 and become activated to stimulate the Smad3 pathway. Moreover, SMYD3 and ITGB6 could facilitate the release of latent TGFβ1 from 3D-cultured ovarian cancer spheroids. Interestingly, TGFβ1 could promote the expression of SMYD3 and ITGB6 via feedback. This positive feedback loop could further amplify the biological effect and promote the invasion and adhesion of ovarian cancer spheroids.ConclusionOur results demonstrated that the SMYD3/ITGB6/TGFβ1-Smad3 positive feedback loop could promote the invasion and adhesion of ovarian cancer spheroids by upregulating the expression of N-cadherin, Snail, and Vimentin and downregulating the expression of E-cadherin. Thus, our study unmasked the mechanism of SMYD3- and ITGB6-induced ovarian cancer metastasis and provides new ideas for targeted ovarian cancer treatment.
Highlights
Ovarian cancer is the most lethal gynecological malignancy worldwide, and the lifetime risks of developing and dying from ovarian cancer are 0.72% and 0.45%, respectively [1, 2]
We found that SET and MYND domain-containing protein 3 (SMYD3) and ITGB6 could promote the release and activation of latent TGFb1 and increase the phosphorylation of Smad3 activated by TGFb1 in ovarian cancer spheroids
Using a 3D culture model to mimic the suspended growth conditions in ascites, we found that SMYD3 could enhance the adhesion and invasion of ovarian cancer spheroids and promote metastasis of ovarian cancer in vivo by upregulating the expression of ITGB6 and ITGAM [7]
Summary
Ovarian cancer is the most lethal gynecological malignancy worldwide, and the lifetime risks of developing and dying from ovarian cancer are 0.72% and 0.45%, respectively [1, 2]. Over 70% of epithelial ovarian cancer (EOC) patients have intra-abdominal dissemination involving local invasion of pelvic and abdominal organs but rarely have vascular metastasis at diagnosis [3]. This is mainly because of the unique characteristics of implantation metastasis in EOC, including detachment from the original lesion, formation of spheroids in ascites, adherence to peritoneal mesothelial cells, and anchoring to the stroma. Biological features such as the adhesion and invasion potential of spheroid cells account for EOC recurrence [4]. The potential mechanisms underlying the SMYD3/integrinmediated invasion and adhesion of spheroids still need to be explored
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
