Rabbit Anti-Human PAK1 (a.a. 252-501) Polyclonal antibody

Objective: The present study aimed to investigate the expression of Numb in ovarian cancer tissues and to assess the effect of Numb on cell proliferation, invasion, and EMT in ovarian cancer. Methods: Real-time PCR and Western blotting were used to detect the mRNA and protein expression of Numb, PAK1, beta-catenin, and epithelial-mesenchymal transition (EMT)-related proteins. MTT was employed to check the effect of Numb on proliferation of ovarian cancer cells. Transwell assay was performed to examine the functions of Numb and PAK1 on migration and invasion of ovarian cancer cells. Results: The Numb expression was significantly downregulated while PAK1 and beta-catenin were significantly upregulated in both ovarian cancer tissues and cell lines. Silencing of Numb promoted cell proliferation, migration, invasion, and EMT in ovarian cancer cell lines while overexpressed Numb reversed the above effects. Moreover, the EMT process induced by the inhibition of Numb was regulated through Numb-mediated PAK1/beta-catenin signaling pathway. Conclusion: Numb was downregulated and associated with cell proliferation, invasion, and EMT in ovarian cancer through regulating PAK1/beta-catenin signaling, providing a novel potential biomarker and potential therapeutic target for ovarian cancer.

Although PKC-mediated phosphorylation of protein kinase D1 (PKD1) has been extensively characterized, little is known about PKD1 regulation by other upstream kinases. Here we report that stimulation of epithelial or fibroblastic cells with G protein-coupled receptor agonists, including angiotensin II or bombesin, induced rapid and persistent PKD1 phosphorylation at Ser(203), a highly conserved residue located within the PKD1 N-terminal domain. Exposure to PKD or PKC family inhibitors did not prevent PKD1 phosphorylation at Ser(203), indicating that it is not mediated by autophosphorylation. In contrast, several lines of evidence indicated that the phosphorylation of PKD1 at Ser(203) is mediated by kinases of the class I PAK subfamily, specifically 1) exposing cells to four structurally unrelated PAK inhibitors (PF-3758309, FRAX486, FRAX597, and IPA-3) that act via different mechanisms abrogated PKD1 phosphorylation at Ser(203), 2) siRNA-mediated knockdown of PAK1 and PAK2 in IEC-18 and Swiss 3T3 cells blunted PKD1 phosphorylation at Ser(203), 3) phosphorylation of Ser(203) markedly increased in vitro when recombinant PKD1 was incubated with either PAK1 or PAK2 in the presence of ATP. PAK inhibitors did not interfere with G protein-coupled receptor activation-induced rapid translocation of PKD1 to the plasma membrane but strikingly prevented the dissociation of PKD1 from the plasma membrane and blunted the phosphorylation of nuclear targets, including class IIa histone deacetylases. We conclude that PAK-mediated phosphorylation of PKD1 at Ser(203) triggers its membrane dissociation and subsequent entry into the nucleus, thereby regulating the phosphorylation of PKD1 nuclear targets, including class IIa histone deacetylases.