Pard3 suppresses glioma invasion by regulating RhoA through atypical protein kinase C/NF-κB signaling.

Junjun Li,Tao Huang,Qiangping Wang,Nanxiang Xiong,Hao Xu,Peng Fu,Hongyang Zhao,Omarkhalil Anas

doi:10.1002/cam4.2063

Abstract

Partitioning defective protein 3 (Pard3) has been reported to inhibit the progression of numerous human cancer cell types. However, the role of Pard3 in glioma progression remains unclear. In this study, the expression of Pard3 was measured in human gliomas of different grades by both quantitative polymerase chain reaction and Western blotting. The effect of Pard3 on glioma progression was tested using cell counting kit‐8 assays, EdU assays, colony formation assays, cell migration, and invasion assays and tumor xenografts. The effect of Pard3 on Ras homolog family member A (RhoA) protein levels, subcellular localization, and transcriptional activity was measured by immunoblotting and immunofluorescence. Our results indicate that Pard3 functions as a tumor suppressor in gliomas and that the loss of Pard3 protein is strongly associated with a higher grade and poorer outcome. Pard3 overexpression inhibits glioma progression by upregulating RhoA protein levels. However, the level of GTP‐RhoA protein remained unchanged. Further evidence demonstrates that Pard3 regulates RhoA protein levels, subcellular localization and transcriptional activity by activating atypical protein kinase C/NF‐κB signaling. Mouse modeling experiments show that Pard3 overexpression inhibits glioma cell growth in vivo. Taken together, these findings identify RhoA as a novel target of Pard3 in gliomas and substantiate a novel regulatory role for Pard3 in glioma progression. This study reveals that Pard3 plays an inhibitory role in gliomas by regulating RhoA, which reveals a potential benefit for Pard3 activators in the prevention and therapy of gliomas.

Highlights

Malignant gliomas are the most common and most lethal cancer originating from the central nervous system,[1] and these cancers account for more than 40% of all central nervous system tumors, and are characterized rapid progression and poor prognosis
Our results revealed that the reduction in Pard[3] expression was significantly correlated with Karnofsky Performance Scale (KPS) score (P = 0.04) and recurrence (P = 0.01, Table 1), which is consistent with KPS as an independent predictor of survival.[19]
We examined the levels of GTP‐bound Ras homolog family member A (RhoA) using Glutathione S transferase (GST) pull‐down experiments and found that it was relatively unchanged

Summary

| INTRODUCTION

Malignant gliomas are the most common and most lethal cancer originating from the central nervous system,[1] and these cancers account for more than 40% of all central nervous system tumors, and are characterized rapid progression and poor prognosis. RhoA (Ras homolog family member A) acts as a cancer suppressor gene and plays a significant role in tumor progression.[8] Previous findings indicate that the Rho/ROCK pathway is actively involved in the regulation of glioma cell death.[9] RhoA is an important suppressor of EMT (Epithelial‐mesenchymal transition)[10]; the loss of RhoA is correlated with tumor grade and predicts a poor outcome in patient.[11]. Previous studies have reported on the clinical significance of Pard[3] in lung squamous cell carcinomas,[12] breast cancers,[7] renal cell carcinomas, and esophageal squamous cell carcinomas.[13] These studies showed that Pard[3] is downregulated in these cancers and a marker for poor prognosis and tumor aggressiveness, indicating that Pard[3] plays a vital role in the progression of numerous tumor types. We analyzed the effect of Pard[3] on the migration of malignant glioma cells and found that Pard[3] suppresses glioma cell invasion by regulating RhoA through aPKC/NF‐κB signaling

| MATERIAL AND METHODS

| RESULTS

| DISCUSSION

Findings

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