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PAK1

Official Full Name
p21 protein (Cdc42/Rac)-activated kinase 1
Background
Alpha PAK p68, beta PAK p65 and gamma PAK p62 are three isoforms of serine/threonine kinases. These three isoforms complex specifically with Rac1 and Cdc42 in their active GTP-bound state, inhibiting their intrinsic GTPase activity leading to their autophosphorylation.
Synonyms
PAK1; p21 protein (Cdc42/Rac)-activated kinase 1; p21/Cdc42/Rac1 activated kinase 1 (STE20 homolog, yeast) , p21/Cdc42/Rac1 activated kinase 1 (yeast Ste20 related); serine/threonine-protein kinase PAK 1; STE20 homolog; yeast; p65-PAK; alpha-PAK; STE20 homolog, yeast; p21/Cdc42/Rac1-activated kinase 1 (yeast Ste20-related); p21/Cdc42/Rac1-activated kinase 1 (STE20 homolog, yeast); PAKalpha; MGC130000; MGC130001; cb761; wu:fj97h10; p21/Cdc42/Rac1-activated kinase 1

Cat.No. Product Name Price
CLKO-0329PAK1 KO Cell Lysate-HeLaInquiry

Recent Research Progress

P21-activated kinase 1 (PAK1), a ubiquitous serine/threonine protein kinase, is widely regulated in human cancers and plays a fundamental role in related cellular processes such as invadopodia disassembly, cell adhesion and migration and processes that are relevant to metastasis and progression, epithelial to mesenchymal transition (EMT). PAK1 acts as a convergent point in the complex oncogenic signaling pathway, and its dysregulation may affect oncogenic transformation and survival. Several clinical studies and functional studies have demonstrated that PAK1 is involved in tumor metastasis. Studies have confirmed that inhibition of PAK1 in human tumors and in vivo tumor models produces an anti-tumor effect. Clinical studies of molecular therapies targeting PAK1 using small molecule inhibitors have been growing. Recently, the role of PAK1 in DDR has begun to appear. It has recently been shown that PAK1 can phosphorylate microrchidia CW-type zinc finger 2 (MORC2), thereby inducing γH2AX, and plays an important role in the regulation of gene expression modulations that were associated with DNA damage induced by ionizing radiation.

PAK1 and gastric cancer

To date, the CW-type zinc finger 2 (MORC2) of the micro-echtinoderma (MORC) family has been found to be involved in the p21 activated kinase 1 (PAK1) pathway to maintain genomic integrity. PAK1-mediated phosphorylation of MORC2 promotes cell cycle progression, and phosphorylation of MORC2-S677A leads to decreased cell proliferation and tumorigenicity of gastric cancer cells, which is significantly enhanced in overexpression of phosphorylated MORC2-S677E form, indicating the phosphorylation of MORC2 is importance in tumorigenesis. More importantly, in clinical gastric cancer, phosphorylation of MORC2 is positively correlated with PAK1 expression. In addition, high expression of PAK1 and phosphorylation of MORC2 appear to be associated with poor prognosis in clinical gastric cancer. Collectively, these findings revealed novel functions of MORC2 phosphorylation in promoting gastric cell proliferation in vitro and tumorigenesis in vivo, suggesting that blocking PAK1-mediated MORC2 phosphorylation may be a potential therapeutic strategy for gastric tumorigenesis.

PAK1 and AML

The clinical prognosis of acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) is poor, because the current chemotherapy regimen cannot target leukemia stem cells. Recently, PAK1 was identified as a H2.0-like homeobox (HLX), a downstream effector molecule of a gene functionally related to the pathogenesis of AML. Studies have shown that inhibition of PAK1 activity by small molecule inhibitors or RNA interference produces profound leukemia inhibition in vitro and in vivo. Inhibition of PAK1 induces differentiation and apoptosis of AML cells by down-regulating the core network of MYC oncogenes and MYC target genes. Importantly, inhibition of PAK1 inhibits primary human leukemia cells, including those enriched in immature leukemia stem cells. In addition, PAK1 up-regulation occurs during disease progression and is associated with patient survival in MDS. These studies revealed that PAK1 serves as a novel target for AML and MDS and supports the use of PAK1 inhibitors as a therapeutic strategy for these diseases.

PAK1 and PDAC

It has been reported that PAK1 stimulates drug resistance by regulating epithelial-mesenchymal transition and activation of pancreatic stellate cells. The results of Jagadeeshan et al.'s gemcitabine-resistant and sensitive cell line model suggest that gemcitabine resistance is required to increase PAK1 kinase activity. This is evidenced by elevated levels of phosphorylated PAK1 and ribonucleotide reductase M1 in most human PDAC tumors compared to normal controls. The signaling pathway indicates that PAK1 confers gemcitabine resistance by preventing DNA damage, inhibiting apoptosis, and regulating survival signals by NF-κB. Furthermore, PAK1 is an upstream interacting substrate for transforming growth factor beta-activated kinase 1 (a molecule involved in gemcitabine resistance). Molecular mechanism studies have shown that gemcitabine docks with the active site of PAK1. In addition, gemcitabine treatment induces PAK1 kinase activity in both in vivo and cell-free systems. Finally, the results of athymic mouse tumor models indicate that inhibition of PAK1 by IPA-3 enhances the cytotoxicity of gemcitabine and leads to regression of pancreatic tumors. These findings suggest that PAK1-specific inhibitors will prove to be a better adjuvant for existing PDAC chemotherapy regimens.

PAK1 and OSCC

Recently, studies have found that PAK1 is overexpressed in oral cancer cell lines. Stimulation of oral squamous cell carcinoma (OSCC) cells with serum growth factors leads to re-localization of PAK1 and may result in profound cytoskeletal remodeling. It has also been found that PAK1 is involved in invasion, migration and cytoskeletal remodeling of OSCC cells. PAK1 may play a key role in the development of OSCC. Studying the role of PAK1 and its substrates may enhance the understanding of oral cancer and the potential therapeutic value of PAKs in oral cancer.

There is increasing evidence that PAK1 is closely related to the development of cancer and may be a promising target for cancer diagnosis and treatment. Therefore, it is necessary to study the novel binding partner of PAK1, which will be of great significance for the diagnosis and treatment of cancer.

References:

  1. Gan JF, et al. Dysregulation of PAK1 Is Associated with DNA Damage and Is of Prognostic Importance in Primary Esophageal Small Cell Carcinoma. International Journal of Molecular Sciences, 2015, 16: 12035-12050
  2. Wang GL, et al. PAK1-mediated MORC2 phosphorylation promotes gastric tumorigenesis. Oncotarget, 2015, 6(12)
  3. Ashley Pandolfi, et al. PAK1 is a therapeutic target in acute myeloid leukemia and myelodysplastic syndrome. Blood. 2015, 126(9):1118-1127
  4. Jagadeeshan, et al. P21-activated kinase 1 (Pak1) signaling influences therapeutic outcome in pancreatic cancer. Annals of Oncology, 2016, 27: 1546-1556
  5. Parvathy et al. Potential role of p21 Activated Kinase 1 (PAK1) in the invasion and motility of oral cancer cells. BMC Cancer. 2016,16(1):293

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