Pak1/LIMK1/Cofilin Pathway Contributes to Tumor Migration and Invasion in Human Non-Small Cell Lung Carcinomas and Cell Lines

PAK2 promotes proliferation, migration, and invasion of lung squamous cell carcinoma through LIMK1/cofilin signaling pathway

Although the p21-activated kinase 2 (PAK2) is an essential serine/threonine protein kinase, its role in lung squamous cell carcinoma (LUSC) progression has yet to be fully understood. We analyzed PAK2 mRNA levels and DNA copy numbers as well as protein levels by quantitative real-time PCR and immunohistochemical staining, respectively, in human LUSC tissues and adjacent normal tissues. Then, we used colony formation assays, cell counting kit-8 assays, matrigel invasion assays, wound healing assays and xenograft models in nude mice to investigate the functions of PAK2 in LUSC progression. We demonstrated that the mRNA levels, DNA copy numbers, and protein levels of PAK2 were up-regulated in human LUSC tissues than in adjacent normal tissues. In addition, a higher PAK2 expression was correlated with a poorer prognosis in LUSC patients. In the in vitro study, we found that PAK2 promoted cell growth, migration, invasion, EMT process, and cell morphology regulation in LUSC cells. Furthermore, PAK2 enhanced tumor cell proliferation, migration, and invasion by regulating actin dynamics through the LIMK1/cofilin signaling. Our findings implicated that the PAK2/LIMK1/cofilin signaling pathway is likely a potential clinical marker and therapeutic target for LUSC.

p21-Activated Kinase: Role in Gastrointestinal Cancer and Beyond

Simple Summary

Gastrointestinal tumors are the most common tumors with a high mortality rate worldwide. Numerous protein kinases have been studied in anticipation of finding viable tumor therapeutic targets, including PAK. PAK is a serine/threonine kinase that plays an important role in the malignant phenotype of tumors. The function of PAK in tumors is highlighted in cell proliferation, survival, motility, tumor cell plasticity and the tumor microenvironment, therefore providing a new possible target for clinical tumor therapy. Based on the current research works of PAK, we summarize and analyze the PAK features and signaling pathways in cells, especially the role of PAK in gastrointestinal tumors, thereby hoping to provide a theoretical basis for both the future studies of PAK and potential tumor therapeutic targets.

Abstract

Gastrointestinal tumors are the most common tumors, and they are leading cause of cancer deaths worldwide, but their mechanisms are still unclear, which need to be clarified to discover therapeutic targets. p21-activating kinase (PAK), a serine/threonine kinase that is downstream of Rho GTPase, plays an important role in cellular signaling networks. According to the structural characteristics and activation mechanisms of them, PAKs are divided into two groups, both of which are involved in the biological processes that are critical to cells, including proliferation, migration, survival, transformation and metabolism. The biological functions of PAKs depend on a large number of interacting proteins and the signaling pathways they participate in. The role of PAKs in tumors is manifested in their abnormality and the consequential changes in the signaling pathways. Once they are overexpressed or overactivated, PAKs lead to tumorigenesis or a malignant phenotype, especially in tumor invasion and metastasis. Recently, the involvement of PAKs in cellular plasticity, stemness and the tumor microenvironment have attracted attention. Here, we summarize the biological characteristics and key signaling pathways of PAKs, and further analyze their mechanisms in gastrointestinal tumors and others, which will reveal new therapeutic targets and a theoretical basis for the clinical treatment of gastrointestinal cancer.

Helicobacter pylori regulates ILK to influence autophagy through Rac1 and RhoA signaling pathways in gastric epithelial cells

The ability of Helicobacter pylori to manipulate host autophagy is an important pathogenic mechanism. We found an inverse correlation between the expression of ILK and the autophagy marker protein LC3B in H. pylori-positive human samples, H. pylori-infected mice models and H. pylori-infected GES-1 cell lines. When the ILK-knockdown GES-1 cells were infected by H. pylori, CagA were significantly degraded, autophagosomes accumulation and autolysosomes formation were significantly increased, and LC3B protein levels and ratio of LC3BII to LC3BI were also remarkably upregulated. And chloroquine treatment increased LC3B levels in ILK-knockdown GES-1 cells. The expression levels of both Rac1 and RhoA were downregulated in GES-1 cells after H. pylori infection and were decreased in ILK-knockdown GES-1 cells. The mRNA and protein levels of PAK1, MLC, and LIMK were significantly decreased and cofilin mRNA and protein levels were significantly increased in GES-1 cells treated with the Rac1 inhibitor NSC 23766. The mRNA and protein levels of ROCK1, ROCK2, MLC, and LIMK1 were significantly reduced and cofilin mRNA and protein levels were significantly increased in GES-1 cells treated with the RhoA inhibitor CCG-1423. F-actin was significantly reduced in Rac1- or RhoA-inhibited GES-1 cells. F-actin depolymerization induced autophagosomes accumulation, autolysosomes formation, and the increase of LC3B levels in GES-1 cells. Therefore, these findings revealed that ILK could serve as a novel regulator to affect Rac1/PAK1 and RhoA/ROCKs signaling pathways, thereby influencing H. pylori-induced autophagy.

Long non-coding RNA Lnc-408 promotes invasion and metastasis of breast cancer cell by regulating LIMK1

Invasion and metastasis are the leading causes of death in patients with breast cancer (BC), and epithelial-mesenchymal transformation (EMT) plays an essential role in this process. Here, we found that Lnc-408, a novel long noncoding RNA (lncRNA), is significantly upregulated in BC cells undergoing EMT and in BC tumor with lymphatic metastases compared with those without lymphatic metastases. Lnc-408 can enhance BC invasion and metastasis by regulating the expression of LIMK1. Mechanistically, Lnc-408 serves as a sponge for miR-654-5p to relieve the suppression of miR-654-5p on its target LIMK1. Knockdown or knockout of Lnc-408 in invasive BC cells clearly decreased LIMK1 levels, and ectopic Lnc-408 in MCF-7 cells increased LIMK1 expression to promote cell invasion. Lnc-408-mediated enhancement of LIMK1 plays a key role in cytoskeletal stability and promotes invadopodium formation in BC cells via p-cofilin/F-actin. In addition, the increased LIMK1 also facilitates the expression of MMP2, ITGB1, and COL1A1 by phosphorylating CREB. In conclusion, our findings reveal that Lnc-408 promotes BC invasion and metastasis via the Lnc-408/miR-654-5p/LIMK1 axis, highlighting a novel promising target for the diagnosis and treatment of BC.

SphK2/S1P Promotes Metastasis of Triple-Negative Breast Cancer Through the PAK1/LIMK1/Cofilin1 Signaling Pathway

Background

Triple-negative breast cancer (TNBC) features a poor prognosis, which is partially attributed to its high metastatic rate. However, there is no effective target for systemic TNBC therapy due to the absence of estrogen, progesterone, and human epidermal growth factor 2 receptors (ER, PR, and HER-2, respectively) in cancer. In the present study, we evaluated the role of sphingosine kinase 2 (SphK2) and its catalyst sphingosine-1-phosphate (S1P) in TNBC metastasis and the effect of the SphK2-specific inhibitor ABC294640 on TNBC metastasis.

Methods

The function of SphK2 and S1P in TNBC cell metastasis was evaluated using transwell migration and wound-healing assays. The molecular mechanism of SphK2/S1P mediating TNBC metastasis was investigated using Western blot, histological examination, and immunohistochemistry assays. The antitumor activity of ABC294640 was examined in an in vivo TNBC lung metastatic model.

Results

Sphingosine kinase 2 promoted TNBC cell migration through the generation of S1P. Targeting SphK2 with ABC294640 inhibited TNBC lung metastasis in vivo. p21-activated kinase 1 (PAK1), p-Lin-11/Isl-1/Mec-3 kinase 1 (LIMK1), and Cofilin1 were the downstream signaling molecules of SphK2/S1P. Inhibition of PAK1 suppressed SphK2/S1P-induced TNBC cell migration.

Conclusion

Sphingosine kinase 2/sphingosine-1-phosphate promotes TNBC metastasis through the activation of the PAK1/LIMK1/Cofilin1 signaling pathway. ABC294640 inhibits TNBC metastasis in vivo and could be developed as a novel agent for the clinical treatment of TNBC.

NDRG1 regulates Filopodia-induced Colorectal Cancer invasiveness via modulating CDC42 activity

N-myc downstream regulated gene-1 (NDRG1) has been identified as a putative metastasis suppressor gene and proved to be a key player in cancer spreading and proliferation in our previous work. However, the effects of NDRG1 on tumor invasion and the mechanisms behind it are rarely understood. Here we provided in silico evidence that NDRG1 plays a crucial role in actin reorganization in colorectal cancer (CRC). Through in vitro experiments, we next observed filopodia formation was altered in NDRG1-modified cell lines, while cell division cycle-42 (CDC42) displayed excessive activation in NDRG1-silenced cells. Mechanistically, NDRG1 loss disrupts the binding between RhoGDIα and CDC42 and triggers the activation of CDC42 and the downstream cascades PAK1/Cofilin, thereby promotes the formation of filopodia and invasiveness of CRC. The knockdown of NDRG1 led to enhanced dissemination of CRC cells in vivo and correlates with active CDC42 expression. Using clinical sample analysis, we found an elevated level of active CDC42 in patients with advanced T stage, and it was negatively related to NDRG1 expression. In sum, these results uncover a mechanism utilized by NDRG1 to regulate CDC42 activity in coordinating cytoskeleton reorganization, which was crucial in cancer invasion.

Involvement of Actin and Actin-Binding Proteins in Carcinogenesis

The actin cytoskeleton plays a crucial role in many cellular processes while its reorganization is important in maintaining cell homeostasis. However, in the case of cancer cells, actin and ABPs (actin-binding proteins) are involved in all stages of carcinogenesis. Literature has reported that ABPs such as SATB1 (special AT-rich binding protein 1), WASP (Wiskott-Aldrich syndrome protein), nesprin, and villin take part in the initial step of carcinogenesis by regulating oncogene expression. Additionally, changes in actin localization promote cell proliferation by inhibiting apoptosis (SATB1). In turn, migration and invasion of cancer cells are based on the formation of actin-rich protrusions (Arp2/3 complex, filamin A, fascin, α-actinin, and cofilin). Importantly, more and more scientists suggest that microfilaments together with the associated proteins mediate tumor vascularization. Hence, the presented article aims to summarize literature reports in the context of the potential role of actin and ABPs in all steps of carcinogenesis.

Blockage of PAK1 alleviates the proliferation and invasion of NSCLC cells via inhibiting ERK and AKT signaling activity

PURPOSE

P21-activated kinase 1 (PAK1), a serine/threonine protein kinase which functions downstream of RAC and CDC42 GTPase, is activated by a variety of stimuli, including RAS and other growth signaling factors. The extracellular signal kinase (ERK) and protein kinase B (AKT) signal pathways have been implicated in the pathogenesis of cancers. Whether PAK1 is sensitive to KRAS mutation signals and plays a role through ERK and AKT signaling pathways in NSCLC needs to be studied.

METHODS

The expression of PAK1, ERK and AKT was detected in both lung cancer cell lines and clinical samples. PAK1 RNA interference and specific inhibitor of PAK1(IPA-3) were applied to lung cancer cell lines and mouse xenograft tumors. Cell growth was measured by MTT and colony formation assays. Cell migration and invasion were detected by wound healing and transwell assays. RAS mutation was detected by Taqman probe method. Correlation between KRAS, PAK1, ERK and AKT activities was analyzed in lung cancer patients.

RESULTS

PAK1 was highly expressed not only in RAS mutant but also in RAS wild-type lung cancer cells. Using specific inhibitor of PAK1, IPA-3 and PAK1 RNA interference, cell proliferation, migration and invasion of lung cancer cells were reduced significantly, accompanied by decreased activities of ERK and AKT. Dual inhibition of ERK and AKT suppressed these cellular processes to levels comparable to those achieved by reduction in PAK1 expression. In NSCLC patients, PAK1 was not correlated with KRAS mutation but was significantly positively correlated with pERK and pAKT.

CONCLUSION

PAK1 played roles in NSCLC proliferation and invasion via ERK and AKT signaling and suggested a therapeutic target for NSCLC.

Apelin/APJ system: an emerging therapeutic target for respiratory diseases

Apelin is an endogenous ligand of G protein-coupled receptor APJ. It is extensively expressed in many tissues such as heart, liver, and kidney, especially in lung tissue. A growing body of evidence suggests that apelin/APJ system is closely related to the development of respiratory diseases. Therefore, in this review, we focus on the role of apelin/APJ system in respiratory diseases, including pulmonary arterial hypertension (PAH), pulmonary embolism (PE), acute lung injury (ALI)/acute respiratory distress syndrome (ARDS), obstructive sleep apnoea syndrome (OSAS), non-small cell lung cancer (NSCLC), pulmonary edema, asthma, and chronic obstructive pulmonary diseases. In detail, apelin/APJ system attenuates PAH by activating AMPK-KLF2-eNOS-NO signaling and miR424/503-FGF axis. Also, apelin protects against ALI/ARDS by reducing mitochondrial ROS-triggered oxidative damage, mitochondria apoptosis, and inflammatory responses induced by the activation of NF-κB and NLRP3 inflammasome. Apelin/APJ system also prevents the occurrence of pulmonary edema via activating AKT-NOS3-NO pathway. Moreover, apelin/APJ system accelerates NSCLC cells' proliferation and migration via triggering ERK1/2-cyclin D1 and PAK1-cofilin signaling, respectively. Additionally, apelin/APJ system may act as a predictor in the development of OSAS and PE. Considering the pleiotropic actions of apelin/APJ system, targeting apelin/APJ system may be a potent therapeutic avenue for respiratory diseases.

Polyphyllin II inhibits liver cancer cell proliferation, migration and invasion through downregulated cofilin activity and the AKT/NF-κB pathway

The morbidity and mortality of primary liver cancer is one of the highest amongst all cancers. Deficiency of effective treatment and characteristics of cancer metastasis are believed to be responsible for this situation, thus a great demand is required for new agent development. Polyphyllin II (PP2), an important steroidal saponin extracted from Rhizoma Paris, has emerged as a potential anti-cancer agent, but the effects of PP2 in liver cancers and its underlying mechanisms remain unexplored. In our study, we found that PP2 could remarkably suppress the proliferation of two liver cancer cell lines, HepG2 and BEL7402, resulting in significant cell death. Besides, low doses of PP2 have displayed properties that inhibit cellular motility and invasion of liver cancer cells. In addition, we have found that PP2-mediated cofilin activity suppression was implicated in the inhibition of liver cancer cell motility. Decreased expression of two major hydrolytic enzymes (MMP2/MMP9), through the AKT/NF-κB signaling pathway may also be also responsible for this process. Rescue experiments done with either non-phosphorylatable mutant cofilin-1 (S3A) transfection or an activator of the AKT pathway significantly reversed the inhibition effects of PP2 on liver cancer cells. Taken together, we report a potential agent for liver cancer treatment and reveal its underlying mechanisms.

Relationship between p-cofilin and cisplatin resistance in patients with ovarian cancer and the role of p-cofilin in prognosis

OBJECTIVE

This study aims to determine the correlation between p-cofilin expression and cisplatin resistance in patients with ovarian cancer, and also to investigate the role of p-cofilin in prognosis.

PATIENTS AND METHODS

The ovarian cancer cell line A2780/DDP resistant to cisplatin was prepared. The cell resistance to cisplatin was measured via MTT assay. The cell invasion capacity was identified via Transwell assay. The mRNA expression and protein level was evaluated via semi-quantitative PCR and Western blot, respectively. The tumor tissues of patients with cisplatin-resistant ovarian cancer were collected. The relationship between prognosis and p-cofilin expression was analyzed.

RESULTS

The growth rate of A2780 was similar to that of A2780/DDP. The sensitivity of A2780 to cisplatin was significantly higher than that of A2780/DDP (p< 0.01). The migration capacity of A2780/DDP was significantly increased compared to that of A2780 (p< 0.01), indicating that the cisplatin-resistant cell lines were successfully constructed. Both CFL1 mRNA level and p-cofilin level in A2780/DDP was significantly higher than that in A2780 (p< 0.01). The p-cofilin level in cancer tissues in patients with cisplatin-resistant ovarian cancer was significantly higher than that in patients with cisplatin-sensitive ovarian cancer (p< 0.01). The cisplatin resistance was positively correlated with the p-cofilin expression level (r= 0.802, p= 0.023). The survival time of patients with normal or low level of p-cofilin was significantly longer than that of patients with high expression.

CONCLUSION

The cisplatin resistance of ovarian cancer is closely related to the expression level of p-cofilin, which affects the prognosis of patients with ovarian cancer.

Long Non-coding RNA PVT1 Competitively Binds MicroRNA-424-5p to Regulate CARM1 in Radiosensitivity of Non-Small-Cell Lung Cancer

Accumulating evidence revealed that dysregulated long non-coding RNAs (lncRNAs) were involved in tumorigenesis and progression. This study is supposed to reveal the effects of lncRNA PVT1 on the radiosensitivity of non-small-cell lung cancer (NSCLC) via the microRNA (miR)-424-5p/lncRNA PVT1/CARM1 signaling pathway. Differentially expressed lncRNA was filtrated. The co-expressed gene of lncRNA was predicted, and gene ontology analysis was performed to find out the genes associated with NSCLC radiosensitivity. The miR that was combined with lncRNA and mRNA was filtrated. Two cell lines with the highest expressed PVT1 were selected, followed by transfection with a series of different mimic, inhibitor, or siRNA. RIP assay was employed for the interaction between PVT1 and CARM1. The regulatory effect of miR-424-5p on cell proliferation, migration, invasion, cycle, and apoptosis was investigated. PVT1 was the most remarkable lncRNA that upregulated in NSCLC. CARM1 co-expressed with lncRNA PVT1 and associated with NSCLC radiosensitivity. Both lncRNA PVT1 and CARM1 can combine with miR-424-5p. Increased PVT1, CARM1, MMP-2, MMP-9, and Bcl-2 and decreased miR-424-5p and Bax were found in NSCLC tissues. PVT1 was targeted by miR-424-5p. After silencing of PVT1 or overexpressed miR-424-5p, decreased PVT1, CARM1, MMP-2, MMP-9, and Bcl-2 inhibited cell proliferation, migration, and invasion but promoted miR-424-5p, Bax, and cell apoptosis. The present study confirms the radiosensitivity of NSCLC radiotherapy can be increased by siRNA-PVT1 and overexpressed miR-424-5p.

MicroRNA-384 inhibits the progression of esophageal squamous cell carcinoma through blockade of the LIMK1/cofilin signaling pathway by binding to LIMK1

INTRODUCTION

Esophageal squamous cell carcinoma (ESCC) represents an aggressive malignancy often accompanied with a poor prognosis. Owing to the poor mortality and morbidity rates associated with this malignancy, a deeper understanding of the finer molecular changes that occur in ESCC is required in order to identify novel potential targets for early detection and therapy. At present the mechanism by which ESCC functions on a molecular level is not fully understood. Hence, the aim of the present study was to ascertain as to whether microRNA-384 (miR-384) influences the progression of ESCC.

MATERIAL AND METHODS

Bioinformatics analysis was initially conducted to identify ESCC-related differentially expressed genes and predict regulatory miRs. After the target relationship between miR-384 and LIMK1 had been verified, the expression of miR-384 and LIMK1 in the EC9706 cell line was altered in an attempt to investigate the regulatory roles of miR-384 in the expression of the LIMK1/cofilin signaling pathway-related genes, cell proliferation, invasion, cell cycle distribution and apoptosis, in addition to lymph node metastasis (LNM) and tumor growth in nude mice.

RESULTS

Microarray-based gene expression profiling indicated that miR-384 affected the progression of ESCC through the LIMK1-mediated LIMK1/cofilin signaling pathway. Furthermore, miR-384 and Bax were observed to be poorly expressed, while LIMK1, cofilin and Bcl-2 were highly expressed in ESCC. The obtained evidences indicating that miR-384 targeted and negatively regulated LIMK1. Upregulation of miR-384 or LIMK1 inhibition was determined to block the LIMK1/cofilin signaling pathway, repress cell proliferation, invasion, cell cycle, LNM and tumor growth, while promote cell apoptosis in ESCC.

CONCLUSION

Collectively, based on the key findings of the study, miR-384 could sequester LIMK1, which acts to suppress activation of the LIMK1/cofilin signaling pathway, thus ultimately inhibiting the development and progression of ESCC.

Neural Wiskott-Aldrich syndrome protein (nWASP) is implicated in human lung cancer invasion

Abstract

Lung cancer is one of the most commonly diagnosed cancers with survival much lower in patients diagnosed with distal metastases. It is therefore imperative to identify pathways involved in lung cancer invasion and metastasis and to consider the therapeutic potential of agents that can interfere with these molecular pathways. This study examines nWASP expression in human lung cancer tissues and explores the effect of nWASP inhibition and knockdown on lung cancer cell behaviour.

Methods

QPCR has been used to measure nWASP transcript expression in human lung cancer tissues. The effect of wiskostatin, an nWASP inhibitor, on A-549 and SK-MES-1 lung carcinoma cell growth, adhesion, migration and invasion was also examined using several in vitro functional assays, including ECIS, and immunofluorescence staining. The effect of nWASP knockdown using siRNA on particular behaviours of lung cancer cells was also examined.

Results

Patients with high levels of nWASP expression in tumour tissues have significantly lower survival rates. nWASP transcript levels were found to correlate with lymph node involvement (p = 0.042). nWASP inhibition and knockdown was shown to significantly impair lung cancer cell growth. nWASP inhibition also affected other cell behaviours, in SK-MES-1 invasion and A-549 cell motility, adhesion and migration. Paxillin and FAK activity are reduced in lung cancer cell lines following wiskostatin and nWASP knockdown as shown by immunofluorescence and western blot.

Conclusions

These findings highlight nWASP as an important potential therapeutic target in lung cancer invasion and demonstrate that inhibiting nWASP activity using the inhibitor wiskostatin can significantly alter cell behaviour in vitro.

Zerumbone Suppresses Osteopontin-Induced Cell Invasion Through Inhibiting the FAK/AKT/ROCK Pathway in Human Non-Small Cell Lung Cancer A549 Cells

Lung cancer is the most frequently diagnosed cancer and the leading cause of cancer deaths in the United States and Korea. We have previously demonstrated that osteopontin (OPN) induces cell invasion through inactivating cofilin. Inactivation of cofilin is mediated by the FAK/AKT/Rho-associated kinase (ROCK) pathway in human nonsmall cell lung cancer (NSCLC) cells. Zerumbone (1) has been shown to exert anticancer activities. In this study, whether and how 1 affects OPN-induced cell invasion was determined in NSCLC A549 cells. Results from Boyden chamber assays suggested that OPN induced invasion of A549 cells and that 1 strongly suppressed this activity without affecting cell viability. Compound 1 effectively inhibited OPN-induced protein expression of ROCK1, the phosphorylation of LIM kinase 1 and 2 (LIMK1/2), and cofilin. In addition, immunofluorescence staining showed that OPN caused a significant increase in lamellipodia formation at the leading edge of cells. However, 1 dramatically decreased OPN-induced lamellipodia formation. Compound 1 impaired OPN-induced phosphorylation of FAK and AKT, as determined by Western blot analysis. Taken together, these results suggest that 1 causes considerable suppression of OPN-induced cell invasion through inhibiting the FAK/AKT/ROCK pathway in NSCLC A549 cells.

Myoferlin expression in non-small cell lung cancer: Prognostic role and correlation with VEGFR-2 expression

Myoferlin is a protein that is associated with cellular repair following injury. The expression of myoferlin in breast cancer and pancreatic adenocarcinoma has been reported to correlate with tumor invasiveness, epithelial to mesenchymal transition and an adverse prognosis. In the present study, myoferlin expression was investigated in non-small cell lung carcinoma (NSCLC), along with its association with patient prognosis and the expression of a number of other proteins. A total of 148 patients exhibiting NSCLC were enrolled in the present study. The survival data of all patients was examined, and myoferlin, vascular endothelial growth factor receptor-2 (VEGFR-2), epidermal growth factor receptor, E-cadherin, β-catenin, thyroid transcription factor-1 and tumor protein p63 expression was investigated via immunohistochemical staining of tissue microarrays. Myoferlin expression was detected in the cytoplasm of 75/148 (50.7%) of the NSCLC cases. In the adenocarcinoma cases, myoferlin-positive patients possessed a poorer prognosis (odds ratio, 2.94; P=0.339). In the squamous cell carcinoma cases, myoferlin expression was significantly associated with VEGFR-2 expression (P=0.001). Immunohistochemical staining for VEGFR-2 and myoferlin expression indicated similar features and cytoplasmic staining in tumor cells. As VEGFR-2 is a significant target for novel anticancer therapies, it is anticipated that myoferlin may also possess the potential to become a novel clinical target for the treatment of NSCLC.

Potentially functional polymorphisms in PAK1 are associated with risk of lung cancer in a Chinese population

P21-activated kinase 1(PAK1) plays an important role in the regulation of cell morphogenesis, motility, mitosis, and angiogenesis and has been implicated with tumorigenesis and tumor progression. We hypothesized that functional polymorphisms in PAK1 gene may modify the risk of lung cancer. We screened four potentially functional polymorphisms (rs2154754, rs3015993, rs7109645, and rs2844337) in PAK1 gene and evaluated the association between the genetic variants and lung cancer risk in a case–control study including 1341 lung cancer cases and 1982 cancer-free controls in a Chinese population. We found that variant allele of rs2154754 was significantly associated with a decreased risk of lung cancer (OR = 0.85, 95% CI: 0.77–0.95, P = 0.004), meanwhile the result of rs3015993 was marginal (OR = 0.90, 95%CI: 0.81–1.00, P = 0.044). After multiple comparisons, rs2154754 was still significantly associated with the lung cancer risk (P < 0.0125 for Bonferroni correction). We also detected a significant interaction between rs2154754 genotypes and smoking levels on lung cancer risk (P = 0.042). Combined analysis of these two polymorphisms showed a significant allele-dosage association between the number of protective alleles and reduced risk of lung cancer (P_trend = 0.008). These findings indicate that genetic variants in PAK1 gene may contribute to susceptibility to lung cancer in the Chinese population.

P21-activated kinase 1 and 4 were associated with colorectal cancer metastasis and infiltration

BACKGROUND

P21-activated kinases (PAKs) are small guanosine triphosphate effectors that play critical roles in many fundamental cellular functions, including cytoskeletal reorganization and cell motility. PAKs are widely expressed in a variety of tissues and are often overexpressed in multiple cancer types. The aim of this study was to investigate the relationship between PAK1 and PAK4 and clinicopathologic features of colorectal cancer.

METHODS

PAK1 and PAK4 expression in colorectal cancer patients were investigated via TaqMan real-time polymerase chain reaction and immunohistochemistry and clinical analysis.

RESULTS

The relative expression levels of PAK1 and PAK4 gene in colorectal carcinoma tissues were significantly higher than those in normal tissues (P < 0.01). PAK4 expression was higher than PAK1 in the same cancer tissue. The expression of PAK1 and PAK4 increased gradually with the clinical stages in carcinoma tissues (P < 0.01). PAK1 expression was higher in lymph node positive patients, and PAK4 expression was higher in infiltration into serous layer patients (P < 0.05). PAK1 overexpression group has a higher recurrence/metastasis rate compared with that of the PAK1 low expression group. Follow-up analysis showed that the median progression-free survival time of the PAK1 high expression group was significantly shorter than that of the PAK1 low expression group.

CONCLUSIONS

PAK1 and PAK4 expression were associated with colorectal cancer metastasis and infiltration, PAK1 high expression may indicate poor prognosis of colorectal cancer.

Cofilin-phosphatase slingshot-1L (SSH1L) is over-expressed in pancreatic cancer (PC) and contributes to tumor cell migration

Slingshot-1L (SSH1L), a cofilin-phosphatase, plays a role in actin dynamics and cell migration by reactivating cofilin-1. However, the expression of SSH1L in malignant diseases is poorly understood. The overexpression of SSH1L in cancerous tissue compared to the matched surrounding non-cancerous tissues from patients with late stages (III-IV) of PC was detected in 90% (9/10) of cases by western blotting. The expression of SSH1L was shown to be upregulated in tumor cells from 10.7% (11/102) of patients with pancreatic cancer (PC) by immunohistochemistry (IHC). The positive rate of SSH1L in patients with PC at stage VI (TNM) categorized as grade 3 was of 50% (2/4) and 15% (6/40), respectively. Moreover, SSH1L expression was shown to be up-regulated in the PC cell lines (KLM1, PANC-1 and MIAPaCa-2) with high metastatic potential. Loss of SSH1L expression was associated with an increase in the phosphorylation of cofilin-1 at serine-3 and further inhibited cell migration (but not proliferation) in KLM1, PANC-1 and MIAPaCa-2. Actin polymerization inhibitor cytochalasin-D was sufficient to abrogate cell migration of PC without changing SSH1L expression. These results reveal that SSH1L is upregulated in a subset of PCs and that the SSH1L/cofilin-1 signal pathway is associated positively in PC with cell migration. Our study may thus provide potential targets to prevent and/or treat PC invasion and metastasis in patients with SSH1L-positive PC.

Overexpression of LIMK1 promotes tumor growth and metastasis in gastric cancer

Gastric cancer is the second-leading cause of cancer death in Asia. Despite improvement of therapies, the outcome in patients remains extremely poor because of metastasis. In the present study, we found that LIMK1 is overexpressed in gastric cancer, and its expression level correlate with tumor size, lymph node metastasis and TNM stage. Knockdown of LIMK1 expression could inhibit cell proliferation, migration and invasion in vitro, as well as suppress the activation of FAK/paxillin pathway. Moreover, knockdown of LIMK1 expression retarded tumor growth and peritoneal ametastasis in vivo. This highlights that LIMK1 might be used as a potential target in the treatment of gastric cancer.

Upregulation of Limk1 caused by microRNA-138 loss aggravates the metastasis of ovarian cancer by activation of Limk1/cofilin signaling

LIM kinase 1 (Limk1) is associated with cell prolife-ration and metastasis and its dysregulated expression has been observed in many types of cancer. The present study aimed to examine the role of Limk1 in the development of ovarian cancer, as well as the underlying molecular mechanism involved. The results showed that increased Limk1 and decreased miR-138 expression co-existed in ovarian cancer. Furthermore, knockout of Limk1 or the overexpression of miR-138 resulted in reduced cell invasion and migration, while silencing of miR-138 led to enhancement of the invasion and migration of ovarian cancer cells. Cell growth was inhibited by the overexpression of miR-138, although not by the knockout of Limk1. miR-138 directly targeted Limk1 and inhibited ovarian cancer cell growth by PCNA and Bcl-2. Moreover, Limk1/cofilin/p-cofilin is likely a critical signaling pathway involving in miR-138 modulation of ovarian cancer cell metastasis. The results provide evidence supporting miR-138/Limk1 as a novel diagnostic or therapeutic target for ovarian cancer.

MiR-20a inhibits cutaneous squamous cell carcinoma metastasis and proliferation by directly targeting LIMK1

BACKGROUND

MicroRNA-20a (miR-20a) plays a key role in tumorigenesis and progression. But its function is reverse in different kinds of malignant tumor, and its role and mechanism in cutaneous squamous cell carcinoma (CSCC) remains unclear.

OBJECT

To determine the miR-20a's roles in CSCC and confirm whether LIMK1 is a direct target gene of miR-20a.

METHODS

First miR-20a and LIMK1 expression levels were detected in six pairs of CSCC tissues and corresponding normal skin by qRT-PCR. Then MTT assays and colony formation assays were performed to evaluate the impact of miR-20a on cell proliferation. In addition, scratch migration assays and transwell invasion assays were performed to check miR-20a's effect on cell metastasis. Since LIMK1 (LIM kinase-1) was predicted as a target gene of miR-20a, the changes of LIMK1 protein and mRNA were measured by western blot and qRT-RCR methods after miR-20a overexpression. Moreover the dual reporter gene assay was performed to confirm whether LIMK1 is a direct target gene of miR-20a. Finally LIMK1 mRNA and miR-20a in other 30 cases of CSCC pathological specimens were determined and a correlation analysis was evaluated.

RESULTS

The miR-20a significantly low-expressed in CSCC tissues compared with that in matched normal tissues while LIMK1 has a relative higher expression. MiR-20a inhibited A431 and SCL-1 proliferation and metastasis. Both of LIMK1 protein and mRNA levels were downregulated after miR-20a overexpression. The dual reporter gene assays revealed that LIMK1 is a direct target gene of miR-20a. Furthermore, qRT-PCR results of LIMK1 mRNA and miR-20a in 30 cases of CSCC pathological specimens showed miR-20a is inversely correlated with LIMK1 expression.

CONCLUSION

Our study demonstrated that miR-20a is involved in the tumor inhibition of CSCC by directly targeting LIMK1 gene. This finding provides potential novel strategies for therapeutic interventions of CSCC.

Mitochondrial translocation of cofilin-1 promotes apoptosis of gastric cancer BGC-823 cells induced by ursolic acid

The pathogenesis of gastric cancer is characterized by excessive proliferation, abnormal differentiation, and reduced apoptosis. Ursolic acid, extracted from traditional Chinese medicine bearberry, inhibits cell growth and induces apoptosis in gastric cancer. However, the mechanism of the proapoptotic effect of ursolic acid on gastric cancer cells needs further investigation. In our present study, we found in apoptotic gastric cancer BGC-823 cells induced by ursolic acid that a translocation of cofilin-1 protein from the cytoplasm to the mitochondria promoted the release of cytochrome c from the mitochondria to the cytoplasm, thereby activating the caspase cascade and finally inducing gastric cancer cell apoptosis. These results implied that the mitochondrial translocation of cofilin-1 might play a crucial role in the promotion of apoptosis and might be a key target for future treatment of human gastric cancer.

Ursolic acid promotes apoptosis of SGC-7901 gastric cancer cells through ROCK/PTEN mediated mitochondrial translocation of cofilin-1

Ursolic acid, extracted from the traditional Chinese medicine bearberry, can induce apoptosis of gastric cancer cells. However, its pro-apoptotic mechanism still needs further investigation. More and more evidence demonstrates that mitochondrial translocation of cofilin-1 appears necessary for the regulation of apoptosis. Here, we report that ursolic acid (UA) potently induces the apoptosis of gastric cancer SGC-7901 cells. Further mechanistic studies revealed that the ROCK1/PTEN signaling pathway plays a critical role in UA-mediated mitochondrial translocation of cofilin-1 and apoptosis. These findings imply that induction of apoptosis by ursolic acid stems primarily from the activation of ROCK1 and PTEN, resulting in the translocation of cofilin-1 from cytoplasm to mitochondria, release of cytochrome c, activation of caspase-3 and caspase-9, and finally inducing apoptosis of gastric cancer SGC-7901 cells.