Overexpression of activated Cdc42-associated kinase1 (Ack1) predicts tumor recurrence and poor survival in human hepatocellular carcinoma

Domain Architecture of the Nonreceptor Tyrosine Kinase Ack1

The nonreceptor tyrosine kinase (NRTK) Ack1 comprises a distinct arrangement of non-catalytic modules. Its SH3 domain has a C-terminal to the kinase domain (SH1), in contrast to the typical SH3-SH2-SH1 layout in NRTKs. The Ack1 is the only protein that shares a region of high homology to the tumor suppressor protein Mig6, a modulator of EGFR. The vertebrate Acks make up the only tyrosine kinase (TK) family known to carry a UBA domain. The GTPase binding and SAM domains are also uncommon in the NRTKs. In addition to being a downstream effector of receptor tyrosine kinases (RTKs) and integrins, Ack1 can act as an epigenetic regulator, modulate the degradation of the epidermal growth factor receptor (EGFR), confer drug resistance, and mediate the progression of hormone-sensitive tumors. In this review, we discuss the domain architecture of Ack1 in relation to other protein kinases that possess such defined regulatory domains.

Identification of Activated Cdc42-Associated Kinase Inhibitors as Potential Anticancer Agents Using Pharmacoinformatic Approaches

BACKGROUND

Activated Cdc42-associated kinase (ACK1) is essential for numerous cellular functions, such as growth, proliferation, and migration. ACK1 signaling occurs through multiple receptor tyrosine kinases; therefore, its inhibition can provide effective antiproliferative effects against multiple human cancers. A number of ACK1-specific inhibitors were designed and discovered in the previous decade, but none have reached the clinic. Potent and selective ACK1 inhibitors are urgently needed.

METHODS

In the present investigation, the pharmacophore model (PM) was rationally built utilizing two distinct inhibitors coupled with ACK1 crystal structures. The generated PM was utilized to screen the drug-like database generated from the four chemical databases. The binding mode of pharmacophore-mapped compounds was predicted using a molecular docking (MD) study. The selected hit-protein complexes from MD were studied under all-atom molecular dynamics simulations (MDS) for 500 ns. The obtained trajectories were ranked using binding free energy calculations (ΔG kJ/mol) and Gibb's free energy landscape.

RESULTS

Our results indicate that the three hit compounds displayed higher binding affinity toward ACK1 when compared with the known multi-kinase inhibitor dasatinib. The inter-molecular interactions of Hit1 and Hit3 reveal that compounds form desirable hydrogen bond interactions with gatekeeper T205, hinge region A208, and DFG motif D270. As a result, we anticipate that the proposed scaffolds might help in the design of promising selective ACK1 inhibitors.

ACK1 upregulated the proliferation of head and neck squamous cell carcinoma cells by promoting p27 phosphorylation and degradation

Head and neck squamous cell carcinoma (HNSCC) is a malignancy with a worldwide distribution. Although intensive studies have been made, the underlying oncogenic mechanism of HNSCC requires further investigation. In this study, we examined the oncogenic role of activated Cdc42-associated kinase 1 (ACK1), an oncogenic tyrosine kinase, in regulating the proliferation of HNSCC cells and its underlying molecular mechanism. Results from immunohistochemical studies revealed that ACK1 was highly expressed in HNSCC tumors, with 77% (77/100) of tumors showing a high ACK1 immunoreactivity compared to 40% (8/20) of normal mucosa. Knockdown of ACK1 expression in HNSCC cells resulted in elevated p27 expression, reduced cell proliferation, and G1-phase cell cycle arrest. Rescue of ACK1 expression in the ACK1-knockdown cells suppressed p27 expression and restored cell proliferation. Compared to ACK1-knockdown cells, ACK1-rescued cells exhibited a restored p27 expression after MG132 treatment and showed an elevated level of ubiquitinated p27. Our data further showed that knockdown of ubiquitin ligase Skp2 resulted in elevated p27 expression. Importantly, the expression of p27(WT), p27(Y74F), or p27(Y89F) in ACK1-overexpressed 293T cells or ACK1-rescued SAS cells showed higher levels of tyrosyl-phosphorylated p27 and interaction with ACK1 or Skp2. However, the expression of p27(Y88F) mutant exhibited a relatively low phosphorylation level and barely bound with ACK1 or Skp2, showing a basal interaction as the control cells. These results suggested that ACK1 is highly expressed in HNSCC tumors and functions to promote cell proliferation by the phosphorylation and degradation of p27 in the Skp2-mediated mechanism.

β2-adrenergic receptor drives the metastasis and invasion of pancreatic ductal adenocarcinoma through activating Cdc42 signaling pathway

Recent investigations indicate that β2-adrenergic receptor (β2-AR) signaling may facilitate the progression of various tumors, whose underlying mechanisms remain largely elusive. In the present study, we showed that β2-AR recruited Cdc42 in response to isoproterenol (ISO, a β-AR selective agonist) exposure in pancreatic ductal adenocarcinoma (PDAC) cells. The association of β2-AR and Cdc42 promoted the activation of Cdc42, as revealed by increased levels of Cdc42-GTP, and co-incubation with β2-AR antagonist abrogated ISO-induced activation of Cdc42. β2-AR-mediated Cdc42 activation further led to the phosphorylation of downstream PAK1, LIMK1 and Merlin. Furthermore, we showed that the activation of β2-AR/Cdc42 signaling facilitated the migration and invasion of PDAC cells. In addition, β2-AR and Cdc42 were overexpressed in PDAC specimens, compared with adjacent non-tumor tissues. High expression of β2-AR and Cdc42 were correlated with lymph node metastasis and TNM stage in PDAC patients. Finally, we showed that overexpression of β2-AR and Cdc42 were indicative of unfavorable prognosis in PDAC patients. Taken together, our findings suggested that β2-AR might facilitate Cdc42 signaling to drive the migration and invasion of PDAC cells, consequently resulting in the metastasis and dismal prognosis of PDAC. These studies highlight targeting β2-AR/Cdc42 signaling as a therapeutic strategy against PDAC.

Significant Gene Biomarker Tyrosine Kinase Non-receptor 2 Mediated Cell Proliferation and Invasion in Colon Cancer

Objective: This study aimed to investigate the expression and biological functions of TNK2 and miR-125a-3p in colon cancer.

Materials and methods: The expression of TNK2 and miR-125a-3p in colon cancer tissues was analyzed using data deposited on public databases including UALCAN and ONCOMINE. We verified their expression in colon cancer cell lines by RT-qPCR and western blotting. By regulating the expression of TNK2 and miR-125a-3p in colon cancer cells, their functions and potential mechanisms were explored.

Results:TNK2 was overexpressed in colon cancer cell lines, and it was found to directly bind to miR-125a-3p, which was downregulated in these cell lines. Their expression affected the proliferation and invasion of colon cancer cells. Additionally, colon cancer patients with lower TNK2 expression had better prognoses than those with higher TNK2 expression.

Conclusion: Our results indicated that TNK2 and miR-125a-3p play critical roles in colon cancer, and could also serve as biomarkers for the diagnosis and prognosis of this malignant disease.

Targeted inhibition of ACK1 can inhibit the proliferation of hepatocellular carcinoma cells through the PTEN/AKT/mTOR pathway

Activated Cdc42-associated kinase 1 (ACK1) expression is upregulated in hepatocellular carcinoma (HCC) tissues and other tumour tissues. However, the function and regulatory mechanism of ACK1 in HCC remains unclear. In this study, the expression of pTyr284-ACK1, pSer473-AKT and PTEN in HCC was detected by immunohistochemistry, and its clinicopathological significance was analysed. Then, ACK1-targeted small molecule inhibitors AIM-100 and Dasatinib were used to treat cells SK-Hep-1 and HepG2, and changes in activity and biological behaviours of PTEN/AKT/mTOR signalling pathway were observed. The results showed that pTyr284-ACK1 protein was highly expressed in HCC tissues and was related to the poor prognosis of patients; the expression of pTyr284-ACK1 protein was positively correlated with pSer473-AKT and negatively correlated with PTEN. In addition, after treatment either with AIM-100 or Dasatinib, both proliferation of two cells and migration, invasion of SK-Hep-1 cells were all significantly inhibited. Meanwhile, ACK1, pTyr284-ACK1, pSer473-AKT, mTOR and EGFR were down-regulated; PTEN was up-regulated when analysed by western-blot in SK-Hep-1 cells. These results demonstrated that ACK1 may promote HCC development via PTEN/AKT/mTOR pathway. Targeted inhibition of ACK1 may be a novel therapeutic strategy for HCC. SIGNIFICANCE OF THE STUDY: Hepatocellular carcinoma (HCC) is a common malignant tumour with high mortality. Our study showed that ACK1 and pTyr284-ACK1 are highly expressed in HCC and may promote HCC development through the PTEN/AKT/mTOR signalling pathway. Targeted inhibition of ACK1 expression with small inhibitors AIM-100 and Dasatinib may weaken tumour cells ability of proliferation, migration and invasion. Our results suggested that downregulation of ACK1 may be a potential therapeutic strategy for HCC.

High Expression of Cell Division Cycle 42 Promotes Pancreatic Cancer Growth and Predicts Poor Outcome of Pancreatic Cancer Patients

BACKGROUND

Cell division cycle 42 (CDC42), an important member of the Rho family, is overexpressed in various human cancers. However, its expression and role in pancreatic cancer (PC) are not well understood.

AIM

The present study was designed to investigate the expression patterns and underlying cellular mechanisms of CDC42 in PC.

METHODS

First, immunohistochemical analysis, quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting were performed to detect CDC42 expression in clinical pancreatic carcinoma and adjacent tissues. Second, differential expression of CDC42 between PC cells and normal cells was evaluated by qRT-PCR and Western blotting. Third, the correlation between CDC42 expression as well as clinicopathological characteristics and patient survival was analyzed. Finally, CDC42 was knocked down to examine its role both in vivo and in vitro.

RESULTS

The results showed significantly increased CDC42 expression in pancreatic tumor tissues compared with adjacent normal tissues, as revealed by qRT-PCR, Western blotting and immunostaining. Compared to PanC-1 cells, CDC42 expression was downregulated in HPDE6-C7 cells as shown by qRT-PCR and Western blotting. High CDC42 expression was observed in 69.2% (83/120) of pancreatic adenocarcinoma patients and was significantly associated with tumor differentiation (p = 0.013), median tumor size (p = 0.005), tumor infiltration (pT stage, p = 0.04), lymph nodal status (pN stage, p = 0.044) and TNM staging (p = 0.003). Multivariate Cox regression analysis revealed CDC42 expression to be an independent predictor of survival of PC patients (HR 3.0, 95% CI 1.60-5.61, p = 0.001). Finally, we found that CDC42 promoted the proliferation of PanC-1 cells both in vivo and in vitro.

CONCLUSIONS

Our findings reveal that CDC42 might play an important role in promoting PC development, and the findings suggest that CDC42 might serve as a potential prognostic indicator of PC.

Activated Cdc42 kinase 1 and hepatocellular carcinoma

Primary liver cancer includes hepatocellular carcinoma (HCC) and cholangiocellular carcinoma. The incidence of HCC is different between countries and regions. As one of the common malignant tumors in China, HCC has high mortality and is the second most common cause of cancer-related death. Elucidating the molecular mechanism of HCC pathogenesis is important for the diagnosis and treatment of liver cancer in China. The expression of activated Cdc42 kinase 1 (ACK1) has been found in a variety of cancers, and ACK1 participates in the occurrence and development of cancers. However, there are currently few studies about the relationship between ACK1 protein and HCC. This paper reviews the structure characteristics and biological function of ACK1 as well as its relationship with invasion and metastasis of HCC.