Rac1/Pak1/p38/MMP-2 Axis Regulates Angiogenesis in Ovarian Cancer

Polymeric nanofiber leveraged co-delivery of anti-stromal PAK1 inhibitor and paclitaxel enhances therapeutic effects in stroma-rich 3D spheroid models

The role of tumor stroma in solid tumors has been widely recognized in cancer progression, metastasis and chemoresistance. Cancer-associated fibroblasts (CAFs) play a crucial role in matrix remodeling and promoting cancer cell stemness and resistance via reciprocal crosstalk. Residual tumor tissue after surgical removal as well as unresectable tumors face therapeutic challenges to achieve curable outcome. In this study, we propose to develop a dual delivery approach by combining p21-activated kinase 1 (PAK1) inhibitor (FRAX597) to inhibit tumor stroma and chemotherapeutic agent paclitaxel (PTX) to kill cancer cells using electrospun nanofibers. First, the role of the PAK1 pathway was established in CAF differentiation, migration and contraction using relevant in vitro models. Second, polycaprolactone polymer-based nanofibers were fabricated using a uniaxial electrospinning technique to incorporate FRAX597 and/or PTX, which showed a uniform texture and a prolonged release of both drugs for 16 days. To test nanofibers, stroma-rich 3D heterospheroid models were set up which showed high resistance to PTX nanofibers compared to stroma-free homospheroids. Interestingly, nanofibers containing PTX and FRAX597 showed strong anti-tumor effects on heterospheroids by reducing the growth and viability by > 90 % compared to either of single drug-loaded nanofibers. These effects were reflected by reduced intra-spheroidal expression levels of collagen 1 and α-smooth muscle actin (α-SMA). Overall, this study provides a new therapeutic strategy to inhibit the tumor stroma using PAK1 inhibitor and thereby enhance the efficacy of chemotherapy using nanofibers as a local delivery system for unresectable or residual tumor. Use of 3D models to evaluate nanofibers highlights these models as advanced in vitro tools to study the effect of controlled release local drug delivery systems before animal studies.

Identifying patterns to uncover the importance of biological pathways on known drug repurposing scenarios

BACKGROUND

Drug repurposing plays a significant role in providing effective treatments for certain diseases faster and more cost-effectively. Successful repurposing cases are mostly supported by a classical paradigm that stems from de novo drug development. This paradigm is based on the "one-drug-one-target-one-disease" idea. It consists of designing drugs specifically for a single disease and its drug's gene target. In this article, we investigated the use of biological pathways as potential elements to achieve effective drug repurposing.

METHODS

Considering a total of 4214 successful cases of drug repurposing, we identified cases in which biological pathways serve as the underlying basis for successful repurposing, referred to as DREBIOP. Once the repurposing cases based on pathways were identified, we studied their inherent patterns by considering the different biological elements associated with this dataset, as well as the pathways involved in these cases. Furthermore, we obtained gene-disease association values to demonstrate the diminished significance of the drug's gene target in these repurposing cases. To achieve this, we compared the values obtained for the DREBIOP set with the overall association values found in DISNET, as well as with the drug's target gene (DREGE) based repurposing cases using the Mann-Whitney U Test.

RESULTS

A collection of drug repurposing cases, known as DREBIOP, was identified as a result. DREBIOP cases exhibit distinct characteristics compared with DREGE cases. Notably, DREBIOP cases are associated with a higher number of biological pathways, with Vitamin D Metabolism and ACE inhibitors being the most prominent pathways. Additionally, it was observed that the association values of GDAs in DREBIOP cases were significantly lower than those in DREGE cases (p-value < 0.05).

CONCLUSIONS

Biological pathways assume a pivotal role in drug repurposing cases. This investigation successfully revealed patterns that distinguish drug repurposing instances associated with biological pathways. These identified patterns can be applied to any known repurposing case, enabling the detection of pathway-based repurposing scenarios or the classical paradigm.

Identification of Balanol As a Potential Inhibitor of PAK1 That Induces Apoptosis and Cytoprotective Autophagy in Colorectal Cancer Cells

Colorectal cancer (CRC) is a common malignancy of the gastrointestinal tract, often accompanied by poor prognosis and high incidence and mortality. p21 activated kinases (PAKs) have been used as therapeutic targets because of their central role in many oncogenic signaling networks. By exploring tumor databases, we found that PAK1 overexpression is associated with poor prognosis in colorectal cancer, and therefore, PAK1-targeted inhibition is a new potential therapeutic strategy for colorectal cancer. We identified that Balanol (compound 6, DB04098) can effectively target PAK1 by high-throughput virtual screening. In vitro, compound 6 exhibited favorable PAK1 inhibition with potent anti-proliferative and anti-migration activity in SW480 cells. Additionally, we also found that compound 6 induced apoptosis and cytoprotective autophagy in SW480 cells. Together, these results indicate that compound 6 is a potential novel PAK1 inhibitor, which would be utilized as a candidate compound for future CRC treatment.

Pak1 pathway hyper-activation mediates resistance to endocrine therapy and CDK4/6 inhibitors in ER+ breast cancer

Cyclin-dependent kinase 4 and 6 inhibitors (CDK4/6i) have been approved in combination with endocrine therapy (ET) to treat estrogen receptor-positive (ER+) metastatic breast cancer (BC). However, drug resistance represents the leading cause of breast cancer patients mortality. This study aimed to identify novel resistance mechanisms to ER antagonists in combination with CDK4/6 inhibitors. We generated two ER+ BC cell lines, T47D and MCF7, resistant to the combination of the ER antagonist fulvestrant and CDK4/6i abemaciclib, named T47D-FAR and MCF7-FAR. Transcriptomic analysis revealed common up-regulation of genes involved in MAPK and epithelial to mesenchymal transition (EMT) pathways in FAR cells, sustaining their hyper-invasive phenotype and increased anchorage-independent growth, compared to sensitive cells. FAR cells showed higher p21-activated kinase 1 (Pak1) expression and phosphorylation levels than parental cells. PAK1 knockdown by siRNAs hampered cell proliferation, reduced anchorage-independent growth and invasive properties of T47D-FAR and MCF7-FAR, re-sensitizing them to fulvestrant and abemaciclib. Conversely, over-expression of PAK1 in MCF7 and T47D cells increased tumor spheroids' growth and invasion and reduced sensitivity to fulvestrant and abemaciclib, confirming its role in inducing drug resistance. Finally, treatment with Pak1 inhibitors, PF-3758309 (PF309) and NVS-PAK1-1, restored cell sensitivity to fulvestrant and abemaciclib of MCF7-FAR and T47D-FAR cells, both in vitro and in vivo. In conclusion, our data suggested a pivotal role for Pak1 in resistance to ET and CDK4/6i in ER+ breast cancers. These data might promote the rationale for the development of novel Pak1 inhibitors for treatment of patients with ER+ BC progressing on ET plus CDK4/6i.

Targeting P21-Activated Kinase-1 for Metastatic Prostate Cancer

Metastatic prostate cancer (mPCa) has limited therapeutic options and a high mortality rate. The p21-activated kinase (PAK) family of proteins is important in cell survival, proliferation, and motility in physiology, and pathologies such as infectious, inflammatory, vascular, and neurological diseases as well as cancers. Group-I PAKs (PAK1, PAK2, and PAK3) are involved in the regulation of actin dynamics and thus are integral for cell morphology, adhesion to the extracellular matrix, and cell motility. They also play prominent roles in cell survival and proliferation. These properties make group-I PAKs a potentially important target for cancer therapy. In contrast to normal prostate and prostatic epithelial cells, group-I PAKs are highly expressed in mPCA and PCa tissue. Importantly, the expression of group-I PAKs is proportional to the Gleason score of the patients. While several compounds have been identified that target group-I PAKs and these are active in cells and mice, and while some inhibitors have entered human trials, as of yet, none have been FDA-approved. Probable reasons for this lack of translation include issues related to selectivity, specificity, stability, and efficacy resulting in side effects and/or lack of efficacy. In the current review, we describe the pathophysiology and current treatment guidelines of PCa, present group-I PAKs as a potential druggable target to treat mPCa patients, and discuss the various ATP-competitive and allosteric inhibitors of PAKs. We also discuss the development and testing of a nanotechnology-based therapeutic formulation of group-I PAK inhibitors and its significant potential advantages as a novel, selective, stable, and efficacious mPCa therapeutic over other PCa therapeutics in the pipeline.

Anastasis confers ovarian cancer cells increased malignancy through elevated p38 MAPK activation

Activation of executioner caspases was once considered as a point of no return in apoptosis. However, in recent years, accumulating evidence has demonstrated that cells can survive executioner caspase activation in response to apoptotic stimuli through a process called anastasis. In this study, we developed a reporter system, mCasExpress, to track mammalian cells that survive executioner caspase activation. We demonstrate that anastatic ovarian cancer cells acquire enhanced migration following their transient exposure to apoptotic stimulus TRAIL or Paclitaxel. Moreover, anastatic cancer cells secrete more pro-angiogenic factors that enable tumor angiogenesis, growth and metastasis. Mechanistically, we demonstrate that activation of p38 MAPK, which occurs in a caspase-dependent manner in response to apoptotic stress to promote anastasis, persists at a higher level in anastatic cancer cells even after removal of apoptotic stimuli. Importantly, p38 is essential for the elevated migratory and angiogenic capacity in the anastatic cells. Our work unveils anastasis as a potential driver of tumor angiogenesis and metastasis.

Exogenous Klotho ameliorates extracellular matrix degradation and angiogenesis in intervertebral disc degeneration via inhibition of the Rac1/PAK1/MMP-2 signaling axis

Intervertebral disc degeneration (IDD) is highly ubiquitous in the aged population and is an essential factor for low back pain and spinal disability. Because of the association between IDD and senescence, we investigated the ability of the anti-aging drug Klotho to inhibit age-dependent advancement of nucleus pulposus cell (NPC) degeneration. The results indicated that 400 pM exogenous Klotho significantly ameliorated extracellular matrix degradation and angiogenesis. Moreover, we demonstrated that the suppression of angiogenesis and extracellular matrix catabolism was related to inhibition of the Ras-related C3 botulinum toxin substrate 1 (Rac1)/PAK1 axis and matrix metalloproteinase 2 protein expression by exogenous Klotho cotreatment with a Rac1 inhibitor, gene overexpression in NPCs, and stimulation of human umbilical vein endothelial cells with conditioned medium from NPCs. The treatment also preserved the NPC phenotype, viability, and matrix content. In conclusion, these results suggest that the new anti-aging drug Klotho is a potential treatment strategy to mitigate IDD, and thus, provides an innovative understanding of the molecular mechanism of IDD. DATA AVAILABILITY: All data supporting the findings of this study are available from the corresponding authors upon reasonable request.

Dual Fluorescence Isogenic Synthetic Lethal Kinase Screen and High-Content Secondary Screening for MUC16/CA125 Selective Agents

Significant strides have been made in the development of precision therapeutics for cancer. Aberrantly expressed glycoproteins represent a potential avenue for therapeutic development. The MUC16/CA125 glycoprotein serves as a biomarker of disease and a driver of malignant transformation in epithelial ovarian cancer. Previously, we demonstrated a proof-of-principle approach to selectively targeting MUC16+ cells. In this report, we performed a synthetic lethal kinase screen using a human kinome RNAi library and identified key pathways preferentially targetable in MUC16+ cells using isogenic dual florescence ovarian cancer cell lines. Utilizing a separate approach, we performed high-content small-molecule screening of 6 different libraries of 356,982 compounds for MUC16/CA125 selective agents and identified lead candidates that showed preferential cytotoxicity in MUC16+ cells. Compounds with differential activity were selected and tested in various other ovarian cell lines or isogenic pairs to identify lead compounds for Structural Activity Relationship (SAR) selection. Lead siRNA and small molecule inhibitor candidates preferentially inhibited invasion of MUC16+ cells in vitro and in vivo and we show that this is due to decreased activation of MAP kinase, and non-receptor tyrosine kinases. Taken together, we present a comprehensive screening approach to the development of a novel class of MUC16-selective targeted therapeutics and identify candidates suitable for further clinical development.

Establishment of a 3D model of tumor-driven angiogenesis to study the effects of anti-angiogenic drugs on pericyte recruitment

Hepatocellular carcinoma (HCC), as a well-vascularized tumor, has attracted increasing attention in antiangiogenic therapies. Notably, emerging studies reveal that the long-term administration of antiangiogenic drugs induces hypoxia in tumors. Pericytes, which play a vital role in vascular stabilization and maturation, have been documented to be associated with antiangiogenic drug-induced tumor hypoxia. However, the role of antiangiogenic agents in regulating pericyte behavior still remains elusive. In this study, by using immunostaining analysis, we first demonstrated that tumors obtained from HCC patients were highly angiogenic, in which vessels were irregularly covered by pericytes. Therefore, we established a new 3D model of tumor-driven angiogenesis by culturing endothelial cells, pericytes, cancer stem cells (CSCs) and mesenchymal stem cells (MSCs) with microcarriers in order to investigate the effects and mechanisms exerted by antiangiogenic agents on pericyte recruitment during tumor angiogenesis. Interestingly, microcarriers, as supporting matrices, enhanced the interactions between tumor cells and the extracellular matrix (ECM), promoted malignancy of tumor cells and increased tumor angiogenesis within the 3D model, as determined by qRT-PCR and immunostaining. More importantly, we showed that zoledronic acid (ZA) reversed the inhibited pericyte recruitment, which was induced by sorafenib (Sora) treatment, through fostering the expression and activation of ErbB1/ErbB2 and PDGFR-β in pericytes, in both an in vitro 3D model and an in vivo xenograft HCC mouse model. Hence, our model provides a more pathophysiologically relevant platform for the assessment of therapeutic effects of antiangiogenic compounds and identification of novel pharmacological targets, which might efficiently improve the benefits of antiangiogenic treatment for HCC patients.

Stress Hormones: Emerging Targets in Gynecological Cancers

In the past decade, several discoveries have documented the existence of innervation in ovarian cancer and cervical cancer. Notably, various neurotransmitters released by the activation of the sympathetic nervous system can promote the proliferation and metastasis of tumor cells and regulate immune cells in the tumor microenvironment. Therefore, a better understanding of the mechanisms involving neurotransmitters in the occurrence and development of gynecological cancers will be beneficial for exploring the feasibility of using inexpensive β-blockers and dopamine agonists in the clinical treatment of gynecological cancers. Additionally, this article provides some new insights into targeting tumor innervation and neurotransmitters in the tumor microenvironment.

Overexpression of microRNA-19a-3p promotes lymph node metastasis of esophageal squamous cell carcinoma via the RAC1/CDC42-PAK1 pathway

BACKGROUND

A tendency towards extensive regional lymph node metastasis (LNM) is a typical clinical characteristic of esophageal squamous cell carcinoma (ESCC). Up-regulated microRNA (miR)-19a-3p was verified as a predictor of LNM in ESCC in previous microarray analyses, but the underlying mechanisms remain unclear. Here, in vitro experiments were performed to confirm the effect of miR-19a-3p on promoting LNM and to explore the underlying mechanisms.

METHODS

KYSE-150 and TE-1 cell lines were transfected with lentiviral vectors to inhibit miR-19a-3p (LV-miR-19a-3p-inhibition), and cell proliferation, invasion, and migration were assessed. Target genes of miR-19a-3p were identified by sequencing analysis and quantitative reverse transcription PCR (qRT-PCR); Western blotting was performed to confirm targets and explore the potential mechanisms underlying the effect of miR-19a-3p on LNM.

RESULTS

miR-19a-3p had no effect on ESCC cell proliferation, whereas miR-19a-3p overexpression promoted the invasion and migration of ESCC cells. qRT-PCR verification and western blot analysis showed that LV-miR-19a-3p-inhibition downregulated cell division cycle 42 (CDC42), Rac family small GTPase 1 (RAC1), and p21 activated kinase 1 (PAK1).

CONCLUSIONS

Overexpression of miR-19a-3p increased the invasion and migration of ESCC cells via the RAC1/CDC42-PAK1 pathway, suggesting that this pathway mediates the effect of miR-19a-3p on promoting LNM in ESCC.

The R-enantiomer of ketorolac reduces ovarian cancer tumor burden in vivo

BACKGROUND

Rho-family GTPases, including Ras-related C3 botulinum toxin substrate 1 (Rac1) and cell division control protein 42 (Cdc42), are important modulators of cancer-relevant cell functions and are viewed as promising therapeutic targets. Based on high-throughput screening and cheminformatics we identified the R-enantiomer of an FDA-approved drug (ketorolac) as an inhibitor of Rac1 and Cdc42. The corresponding S-enantiomer is a non-steroidal anti-inflammatory drug (NSAID) with selective activity against cyclooxygenases. We reported previously that R-ketorolac, but not the S-enantiomer, inhibited Rac1 and Cdc42-dependent downstream signaling, growth factor stimulated actin cytoskeleton rearrangements, cell adhesion, migration and invasion in ovarian cancer cell lines and patient-derived tumor cells.

METHODS

In this study we treated mice with R-ketorolac and measured engraftment of tumor cells to the omentum, tumor burden, and target GTPase activity. In order to gain insights into the actions of R-ketorolac, we also performed global RNA-sequencing (RNA-seq) analysis on tumor samples.

RESULTS

Treatment of mice with R-ketorolac decreased omental engraftment of ovarian tumor cells at 18 h post tumor cell injection and tumor burden after 2 weeks of tumor growth. R-ketorolac treatment inhibited tumor Rac1 and Cdc42 activity with little impact on mRNA or protein expression of these GTPase targets. RNA-seq analysis revealed that R-ketorolac decreased expression of genes in the HIF-1 signaling pathway. R-ketorolac treatment also reduced expression of additional genes associated with poor prognosis in ovarian cancer.

CONCLUSION

These findings suggest that R-ketorolac may represent a novel therapeutic approach for ovarian cancer based on its pharmacologic activity as a Rac1 and Cdc42 inhibitor. R-ketorolac modulates relevant pathways and genes associated with disease progression and worse outcome.

Multifunctional intracellular matrix metalloproteinases: implications in disease

Matrix metalloproteinases (MMPs) are zinc-dependent endopeptidases that were first discovered as proteases, which target and cleave extracellular proteins. During the past 20 years, however, intracellular roles of MMPs were uncovered and research on this new aspect of their biology expanded. MMP-2 is the first of this protease family to be reported to play a crucial intracellular role where it cleaves several sarcomeric proteins inside cardiac myocytes during oxidative stress-induced injury. Beyond MMP-2, currently at least eleven other MMPs are known to function intracellularly including MMP-1, MMP-3, MMP-7, MMP-8, MMP-9, MMP-10, MMP-11, MMP-12, MMP-14, MMP-23 and MMP-26. These intracellular MMPs are localized to different compartments inside the cell including the cytosol, sarcomere, mitochondria, and the nucleus. Intracellular MMPs contribute to the pathogenesis of various diseases. Cardiovascular renal disorders, inflammation, and malignancy are some examples. They also exert antiviral and bactericidal effects. Interestingly, MMPs can act intracellularly through both protease-dependent and protease-independent mechanisms. In this review, we will highlight the intracellular mechanisms of MMPs activation, their numerous subcellular locales, substrates, and roles in different pathological conditions. We will also discuss the future direction of MMP research and the necessity to exploit the knowledge of their intracellular targets and actions for the design of targeted inhibitors.

Bu-Shen-Huo-Xue Decoction Ameliorates Diabetic Nephropathy by Inhibiting Rac1/PAK1/p38MAPK Signaling Pathway in High-Fat Diet/Streptozotocin-Induced Diabetic Mice

Diabetic nephropathy (DN), a leading cause of end-stage renal disease, is associated with high morbidity and mortality rates worldwide and the development of new drugs to treat DN is urgently required. Bu-Shen-Huo-Xue (BSHX) decoction is a traditional Chinese herbal formula, made according to traditional Chinese medicine (TCM) theory, and has been used clinically to treat DN. In the present study, we established a high-fat diet/streptozotocin-induced diabetic mouse model and treated the mice with BSHX decoction to verify its therapeutic effects in vivo. Ultraperformance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) was applied to analyze the chemical composition and active compounds of BSHX decoction. Markers of podocyte epithelial-mesenchymal transition and the Rac1/PAK1/p38MAPK signaling pathway were evaluated to investigate the mechanism underlying function of BSHX decoction. BSHX decoction effectively alleviated diabetic symptoms, according to analysis of the renal function indicators, serum creatinine, blood urea nitrogen, serum uric acid, and urinary albumin excretion rate, as well as renal histopathology and ultrastructural pathology of DN mice. We identified 67 compounds, including 20 likely active compounds, in BSHX decoction. The podocyte markers, nephrin and podocin, were down-regulated, while the mesenchymal markers, α-SMA and FSP-1, were up-regulated in DN mouse kidney; however, the changes in these markers were reversed on treatment with BSHX decoction. GTP-Rac1 was markedly overexpressed in DN mice and its levels were significantly decreased in response to BSHX decoction. Similarly, levels of p-PAK1 and p-p38MAPK which indicate Rac1 activation, were reduced on treatment with BSHX decoction. Together, our data demonstrated that BSHX decoction ameliorated renal function and podocyte epithelial-mesenchymal transition via inhibiting Rac1/PAK1/p38MAPK signaling pathway in high-fat diet/streptozotocin-induced diabetic mice. Further, we generated a quality control standard and numerous potential active compounds from BSHX decoction for DN.

Platelets, Thrombocytosis, and Ovarian Cancer Prognosis: Surveying the Landscape of the Literature

Platelets are critical components of a number of physiologic processes, including tissue remodeling after injury, wound healing, and maintenance of vascular integrity. Increasing evidence suggests that platelets may also play important roles in cancer. In ovarian cancer, thrombocytosis, both at the time of initial diagnosis and at recurrence, has been associated with poorer prognosis. This review describes current evidence for associations between thrombocytosis and ovarian cancer prognosis and discusses the clinical relevance of platelet count thresholds and timing of assessment. In addition, we discuss several mechanisms from in vitro, in vivo, and clinical studies that may underlie these associations and recommend potential approaches for novel therapeutic targets for this lethal disease.

Rho-GEF trio regulates osteoclast differentiation and function by Rac1/Cdc42

Many bone diseases result from abnormal bone resorption by osteoclasts (OCs). Studying OC related regulatory genes is necessary for the development of new therapeutic strategies. Rho GTPases have been proven to regulate OC differentiation and function and only mature OCs can carry out bone resorption. Here we demonstrate that Rac1 and Cdc42 exchange factor Triple functional domain (Trio) is critical for bone resorption caused by OCs. In this study, we created LysM-Cre;Trio^fl/fl conditional knockout mice in which Trio was conditionally ablated in monocytes. LysM-Cre;Trio^fl/fl mice showed increased bone mass due to impaired bone resorption caused by OCs. Furthermore, our in vitro analysis indicated that Trio conditional deficiency significantly suppressed OC differentiation and function. At the molecular level, Trio deficiency significantly inhibited the expression of genes critical for osteoclastogenesis and OC function. Mechanistically, our researches suggested that perturbed Rac1/Cdc42-PAK1-ERK/p38 signaling could be used to explain the lower ability of bone resorption in CKO mice. Taken together, this study indicates that Trio is a regulator of OCs. Studying the role of Trio in OCs provides a potential new insight for the treatment of OC related bone diseases.

Evaluation of active Rac1 levels in cancer cells: A case of misleading conclusions from immunofluorescence analysis

A large number of aggressive cancer cell lines display elevated levels of activated Rac1, a small GTPase widely implicated in cytoskeleton reorganization, cell motility, and metastatic dissemination. A commonly accepted methodological approach for detecting Rac1 activation in cancer cells involves the use of a conformation-sensitive antibody that detects the active (GTP-bound) Rac1 without interacting with the GDP-bound inactive form. This antibody has been extensively used in fixed cell immunofluorescence and immunohistochemistry. Taking advantage of prostate and pancreatic cancer cell models known to have high basal Rac1-GTP levels, here we have established that this antibody does not recognize Rac1 but rather detects the intermediate filament protein vimentin. Indeed, Rac1-null PC3 prostate cancer cells or cancer models with low levels of Rac1 activation still show a high signal with the anti-Rac1-GTP antibody, which is lost upon silencing of vimentin expression. Moreover, this antibody was unable to detect activated Rac1 in membrane ruffles induced by epidermal growth factor stimulation. These results have profound implications for the study of this key GTPase in cancer, particularly because a large number of cancer cell lines with characteristic mesenchymal features show simultaneous up-regulation of vimentin and high basal Rac1-GTP levels when measured biochemically. This misleading correlation can lead to assumptions about the validity of this antibody and inaccurate conclusions that may affect the development of appropriate therapeutic approaches for targeting the Rac1 pathway.

P21-Activated Kinase 1: Emerging biological functions and potential therapeutic targets in Cancer

The p21-Activated kinase 1 (PAK1), a member of serine-threonine kinases family, was initially identified as an interactor of the Rho GTPases RAC1 and CDC42, which affect a wide range of processes associated with cell motility, survival, metabolism, cell cycle, proliferation, transformation, stress, inflammation, and gene expression. Recently, the PAK1 has emerged as a potential therapeutic target in cancer due to its role in many oncogenic signaling pathways. Many PAK1 inhibitors have been developed as potential preclinical agents for cancer therapy. Here, we provide an overview of essential roles that PAK1 plays in cancer, including its structure and autoactivation mechanism, its crucial function from onset to progression to metastasis, metabolism, immune escape and even drug resistance in cancer; endogenous regulators; and cancer-related pathways. We also summarize the reported PAK1 small-molecule inhibitors based on their structure types and their potential application in cancer. In addition, we provide overviews on current progress and future challenges of PAK1 in cancer, hoping to provide new ideas for the diagnosis and treatment of cancer.

Increased CHST15 follows decline in arylsulfatase B (ARSB) and disinhibition of non-canonical WNT signaling: potential impact on epithelial and mesenchymal identity

Expression of CHST15 (carbohydrate sulfotransferase 15; chondroitin 4-sulfate-6-sulfotransferase; BRAG), the sulfotransferase enzyme that adds 6-sulfate to chondroitin 4-sulfate (C4S) to make chondroitin 4,6-disulfate (chondroitin sulfate E, CSE), was increased in malignant prostate epithelium obtained by laser capture microdissection and following arylsulfatase B (ARSB; N-acetylgalactosamine-4-sulfatase) silencing in human prostate epithelial cells. Experiments in normal and malignant human prostate epithelial and stromal cells and tissues, in HepG2 cells, and in the ARSB-null mouse were performed to determine the pathway by which CHST15 expression is up-regulated when ARSB expression is reduced. Effects of Wnt-containing prostate stromal cell spent media and selective inhibitors of WNT, JNK, p38, SHP2, β-catenin, Rho, and Rac-1 signaling pathways were determined. Activation of WNT signaling followed declines in ARSB and Dickkopf WNT Signaling Pathway Inhibitor (DKK)3 and was required for increased CHST15 expression. The increase in expression of CHST15 followed activation of non-canonical WNT signaling and involved Wnt3A, Rac-1 GTPase, phospho-p38 MAPK, and nuclear DNA-bound GATA-3. Inhibition of JNK, Sp1, β-catenin nuclear translocation, or Rho kinase had no effect. Consistent with higher expression of CHST15 in prostate epithelium, disaccharide analysis showed higher levels of CSE and chondroitin 6-sulfate (C6S) disaccharides in prostate epithelial cells. In contrast, chondroitin 4-sulfate (C4S) disaccharides were greater in prostate stromal cells. CSE may contribute to increased C4S in malignant epithelium when GALNS (N-aceytylgalactosamine-6-sulfate sulfatase) is increased and ARSB is reduced. These effects increase chondroitin 4-sulfates and reduce chondroitin 6-sulfates, consistent with enhanced stromal characteristics and epithelial-mesenchymal transition.

Active RAC1 Promotes Tumorigenic Phenotypes and Therapy Resistance in Solid Tumors

Acting as molecular switches, all three members of the Guanosine triphosphate (GTP)-ase-family, Ras-related C3 botulinum toxin substrate (RAC), Rho, and Cdc42 contribute to various processes of oncogenic transformations in several solid tumors. We have reviewed the distribution of patterns regarding the frequency of Ras-related C3 botulinum toxin substrate 1 (RAC1)-alteration(s) and their modes of actions in various cancers. The RAC1 hyperactivation/copy-number gain is one of the frequently observed features in various solid tumors. We argued that RAC1 plays a critical role in the progression of tumors and the development of resistance to various therapeutic modalities applied in the clinic. With this perspective, here we interrogated multiple functions of RAC1 in solid tumors pertaining to the progression of tumors and the development of resistance with a special emphasis on different tumor cell phenotypes, including the inhibition of apoptosis and increase in the proliferation, epithelial-to-mesenchymal transition (EMT), stemness, pro-angiogenic, and metastatic phenotypes. Our review focuses on the role of RAC1 in adult solid-tumors and summarizes the contextual mechanisms of RAC1 involvement in the development of resistance to cancer therapies.

Pak1 maintains epidermal stem cells by regulating Langerhans cells and is required for skin carcinogenesis

Pak1 (serine/threonine p21-activated kinases) was previously reported to have oncogenic activity in several cancers. However, its roles in the cancer microenvironment are poorly understood. We demonstrated that Pak1 expression in Langerhans cells (LCs) is essential for the maintenance of epidermal stem cells and skin tumor development. We found that PAK1 is localized in LCs by immunohistochemistry. Furthermore, the number of LCs significantly decreased in MSM/Ms Pak1 homozygous knockout mice (MSM/Ms-Pak1^-/-). F₁ hybrid (FVB/N×MSM/Ms) Pak1 heterozygous knockout mice (F₁-Pak1^+/-) had increased numbers of Th17 cells in the skin. Therefore, Pak1 knockdown cells were prepared using LC-derived XS52 cells (XS52-Pak1KD) and co-cultured with keratinocyte-derived C5N cells. As a result, XS52-Pak1KD cell supernatants promoted C5N cell proliferation. We then carried out DMBA/TPA skin carcinogenesis experiments using F₁-Pak1^+/- mice. Of note, F₁-Pak1^+/- mice exhibited stronger resistance to skin tumors than control mice. F₁-Pak1^+/- mice had fewer epidermal stem cells in the skin bulge. Our study suggested that Pak1 regulates the epidermal stem cell number by changing the properties of LCs and functions in skin carcinogenesis. We clarified a novel role of Pak1 in regulating LCs as a potential therapeutic target in skin immune disease and carcinogenesis.

Roles of p38α and p38β mitogen‑activated protein kinase isoforms in human malignant melanoma A375 cells

Skin cancer is one of the most common cancers worldwide. Melanoma accounts for ~5% of skin cancers but causes the large majority of skin cancer‑related deaths. Recent discoveries have shown that the mitogen‑activated protein kinase (MAPK) signaling pathway is critical for melanoma development and progression. Many oncogenic pathways that cause melanoma tumorigenesis have been identified, most of which are due to RAF/MEK/ERK (MAPK) pathway activation. However, the precise role of p38 remains unclear. Using specific short hairpin (sh) RNA to silence p38α and p38β, the present findings demonstrated that p38α was a crucial factor in regulating cell migration in the A375 melanoma cell line. Silencing p38α downregulated the expression of epithelial‑mesenchymal transition markers, such as matrix metallopeptidase (MMP) 2, MMP9, twist family bHLH transcription factor 1, snail family transcriptional repressor 1 and vimentin, while mesenchymal‑epithelial transition markers, such as E‑cadherin, were upregulated. Of note, the results also demonstrated that p38α silencing impaired vascular endothelial growth factor expression, which regulates tumor angiogenesis. Furthermore, p38α knockdown inhibited cell proliferation in melanoma cells. In addition, silencing p38α induced senescence‑like features, but not cell cycle arrest. Expression of the senescence markers p16, p21, p53 and β‑galactosidase was upregulated, and an increase in the number of senescence‑associated β‑galactosidase‑positive cells was observed in a p38α knockdown stable clone. However, no significant difference was found between control and p38β stable knockdown cells. Taken together, the present results suggested that p38α knockdown impaired migration and proliferation, and increased senescence, in A375 melanoma cells. However, p38β may not be involved in melanoma tumorigenesis. Therefore, targeting p38α may be a valuable approach towards inhibiting tumor growth and metastasis in patients with melanoma.

EF2-kinase targeted cobalt-ferrite siRNA-nanotherapy suppresses BRCA1-mutated breast cancer

Aim: To investigate the role of EF2K in BRCA1-mutated breast cancer. Materials & methods: We developed silica coated cobalt-ferrite (CoFe) nanoparticles for in vivo delivery of small interfering RNAs (siRNAs) into BRCA1-mutated breast cancer. Results: Expression of EF2K is highly upregulated in the majority (78.5%) of BRCA1-mutated patients and significantly associated with poor patient survival and metastasis. Silencing of EF2K reduced cell proliferation, migration and invasion of the cancer cells. In vivo therapeutic targeting of EF2K by CoFe-siRNA-nanoparticles leads to sustained EF2K gene knockdown and suppressed tumor growth in orthotopic xenograft models of BRCA1-mutated breast cancer. Conclusion: EF2K is a potential novel molecular target in BRCA1-mutated tumors and CoFe-based siRNA nanotherapy may be used as a novel approach to target EF2K.

AEBP1, a prognostic indicator, promotes colon adenocarcinoma cell growth and metastasis through the NF-κB pathway

The abnormal expression of adipocyte enhancer binding protein 1 (AEBP1) has been implicated in the carcinogenesis and progression of various types of human tumors. However, the role of AEBP1 in colon adenocarcinoma (COAD) remains largely unelucidated. In this study, we explored the clinical significance and biological function of AEBP1 in COAD. We observed that AEBP1 was overexpressed in COAD tissues and cells and that the expression of AEBP1 was correlated with tumor size, the level of histologic differentiation, lymph node metastasis, and cancer stage in COAD patients. In addition, univariate and multivariate Cox regression analyses revealed that high AEBP1 expression suggested poor prognosis in COAD. Moreover, AEBP1 silencing suppressed COAD cell proliferation, migration, and invasion, whereas the upregulation of AEBP1 promoted these behaviors. Additionally, mechanistic studies further demonstrated that AEBP1 promoted COAD cell proliferation, migration, and invasion by upregulating the expression of matrix metalloproteinase-2, vimentin, and TWIST whereas downregulating that of E-cadherin through the nuclear factor-κB pathway. Collectively, these data indicated that AEBP1 may be a new prognostic factor and a potential gene therapy target in COAD.

RAC1 Takes the Lead in Solid Tumors

Three GTPases, RAC, RHO, and Cdc42, play essential roles in coordinating many cellular functions during embryonic development, both in healthy cells and in disease conditions like cancers. We have presented patterns of distribution of the frequency of RAC1-alteration(s) in cancers as obtained from cBioPortal. With this background data, we have interrogated the various functions of RAC1 in tumors, including proliferation, metastasis-associated phenotypes, and drug-resistance with a special emphasis on solid tumors in adults. We have reviewed the activation and regulation of RAC1 functions on the basis of its sub-cellular localization in tumor cells. Our review focuses on the role of RAC1 in cancers and summarizes the regulatory mechanisms, inhibitory efficacy, and the anticancer potential of RAC1-PAK targeting agents.

Modulation of CD44, EGFR and RAC Pathway Genes (WAVE Complex) in Epithelial Cancers

Cancer hallmarks help in understanding the diversity of various neoplasms. Epithelial cancers play an immense role in the tumor biology through Epithelial-Mesenchymal Transition (EMT) process. Receptor tyrosine kinase, as well as phosphatidyl ionositol-3 kinase pathways, play an important role in the regulation of cell proliferation, survival, and differentiation during EMT. Till date, numerous studies have shown modulation in the expression profile of potential targets like CD44, EGFR, and Rac in epithelial cancers. CD44 interacts with EGFR and recruits other molecules which further activate the Rac pathway intermediates. This review mainly focused on modulation of genes like CD44, EGFR, and Rac pathway intermediates which play a crucial role in the tumor progression, metastasis, proliferation, and invasion characteristics in epithelial cancers with EMT properties. Hence, targeting Rac pathway might be a more strategically relevant approach in treating epithelial cancers.

p38 MAP kinases: plausible diagnostic and prognostic serum protein marker of non small cell lung cancer

INTRODUCTION

p38 MAPK signaling molecules plays a dual role in cancer, both progression and suppression. Elevated expression of p38α was reported in lung cancer tissue in rat model. Our objective was to explore the concentration of all 4 isoforms of p38MAPK in serum of Non Small Cell Lung Cancer (NSCLC).

MATERIAL AND METHODS

The blood samples were collected from 77 NSCLC patients, 52 ethically matched healthy controls and 18 follow up patients were collected as some patients expired and some discontinued the treatment. The concentration of all isoforms of p38 (p38α, p38β, p38γ, and p38δ) were evaluated by Surface Plasmon Resonance (SPR) technology.

RESULT

The levels of all isoforms of serum p38 were significantly elevated at pre-therapy compare to control. Only p38α expression was significantly associated with tumor stage and its expression reduced after treatment which is then validated by western blot. However, no changes were observed in other isoforms after therapy.

CONCLUSION

Our study revealed that, p38α is more efficient among all the isoform to predict the disease accurately and it can be concluded that p38 MAPK may be used as diagnostic as well as prognostic marker of NSCLC disease.

TIPE2 acts as a biomarker for GIST risk category and suppresses the viability and invasiveness of GIST cells

Evaluating the risk category of gastrointestinal stromal tumors (GISTs) is crucial for predicting prognosis and choosing treatment strategies, and tumor metastasis usually represent poor prognosis. Tumor necrosis factor-alpha-induced protein 8-like 2 (TIPE2) is a novel described tumor suppressor. In the present study, TIPE2 expression was detected using a total of 96 human GIST specimens by immunohistochemistry. The effect of TIPE2 on proliferation and invasiveness of GIST cells and its related mechanisms were explored in vitro. It was found that TIPE2 expression was gradually decreased in accordance with GIST risk grades and negatively associated with tumor size, mitotic count and risk category. Moreover, TIPE2 was identified as a biomarker for evaluating the risk grade of GIST. TIPE2 markedly suppressed the viability, colony formation, migration and invasion of GIST cells. Furthermore, TIPE2 induced apoptosis and suppressed MMP-9 expression of GIST cells by targeting Rac1. In conclusion, these results indicate that TIPE2 plays a pivotal role in the progression of GIST. TIPE2 serves as a promising biomarker for evaluating GIST risk grade and a potential target for treatment of GIST.

NCK1 promotes the angiogenesis of cervical squamous carcinoma via Rac1/PAK1/MMP2 signal pathway

OBJECTIVE

The study was to explore the roles of Nck1 in the angiogenesis of cervical squamous cell carcinoma (CSCC).

METHODS

mRNA and protein levels were evaluated with real-time quantitative PCR and immunohistochemisty/western blotting respectively. The cancer microvessel density (MVD) was assayed with CD34 endothelial labeling. Nck1 gene knock-in (SiHa-Nck1+) and knock-down (SiHa-Nck1-) were achieved by gene transfection and siRNA respectively. Protein level from cellular supernatant was measured with ELISA. Proliferation, migration and tube formation of the Human Umbilical Vein Endothelial cells (HUVECs) were evaluated by CCK-8 cell viability assay, transwell chamber assay and in vitro Matrigel tubulation assay respectively.

RESULTS

Nck1 level gradually increased from normal cervical epithelia to high-grade CIN, overexpressed in CSCC and was associated with cancer MVD. The ability of proliferation, migration and tube formation of HUVECs was enhanced in SiHa-Nck1+-treated while decreased in SiHa-NcK1--treated cells compared to SiHa-control-treated cells. Mechanistically, RAC1-GTP, p-PAK1 and MMP2 were increased in SiHa-NCK1+ cells and pretreatment with the Rac1 inhibitor (NSC23766) significantly decreased their levels. Furthermore, inhibition of PAK1 reduced MMP2 level in SiHa-Nck1+ cells whereas the level of Rac1-GTP was unaltered. Also, inhibition of Rac1 or PAK1 impaired angiogenesis-inducing capacity of cancer cells.

CONCLUSIONS

Nck1 promotes the angiogenesis-inducing capacity of CSCC via the Rac1/PAK1/MMP2 signal pathway.

RPPAware: A software suite to preprocess, analyze and visualize reverse phase protein array data

Reverse Phase Protein Arrays (RPPA) is a high-throughput technology used to profile levels of protein expression. Handling the large datasets generated by RPPA can be facilitated by appropriate software tools. Here, we describe RPPAware, a free and intuitive software suite that was developed specifically for analysis and visualization of RPPA data. RPPAware is a portable tool that requires no installation and was built using Java. Many modules of the tool invoke R to utilize the statistical features. To demonstrate the utility of RPPAware, data generated from screening brain regions of a mouse model of Down syndrome with 62 antibodies were used as a case study. The ease of use and efficiency of RPPAware can accelerate data analysis to facilitate biological discovery. RPPAware 1.0 is freely available under GNU General Public License from the project website at http://downsyndrome.ucdenver.edu/iddrc/rppaware/home.htm along with a full documentation of the tool.

NDV-D90 suppresses growth of gastric cancer and cancer-related vascularization

Recent reports suggest promises on using oncolytic Newcastle disease viruses (NDV) to treat different cancers, while the effects of a NDV-D90 strain on gastric cancer remain unknown. Here we showed that NDV-D90 induced gastric cancer cell apoptosis in a dose-dependent manner in 3 gastric cancer cell lines BGC-823, SGC-7901 and MKN-28. Pronounced reduction in cell invasion was detected in NDV-D90-treated BGC-823 and SGC-7901 cells, but not in MKN-28 cells. The increases in cell apoptosis and reduction in cell growth in NDV-D90-treated gastric cancer cells seemingly resulted from augmentation of p38 signaling and suppression of ERK1/2 and Akt signaling. In vivo, orthotopic injection of NDV-D90 impaired tumor growth and induced intratumoral necrosis. Tumor cells that had been pre-treated with NDV-D90 showed defect in development of implanted tumor. Moreover, NDV-D90 appeared to reduce gastric tumor vascularization, possibly through suppression of vascular endothelial growth factor A and Matrix Metallopeptidase 2. Together, our data suggest that NDV-D90 may have potential anti-cancer effects on gastric cancer.

Endothelial Cdc42 deficiency impairs endothelial regeneration and vascular repair after inflammatory vascular injury

Background

Endothelial cell (EC) regeneration is essential for inflammation resolution and vascular integrity recovery after inflammatory vascular injury. Cdc42 is a central regulator of cell survival and vessel formation in EC development. However, it is unknown that whether Cdc42 could be a regulating role of EC repair following the inflammatory injury in the lung. The study sought to test the hypothesis that Cdc42 is required for endothelial regeneration and vascular integrity recovery after LPS-induced inflammatory injury.

Methods and results

The role of Cdc42 for the regulation of pulmonary vascular endothelial repair was tested in vitro and in vivo. In LPS-induced acute lung injury (ALI) mouse models, knockout of the Cdc42 gene in ECs increased inflammatory cell infiltration and pulmonary vascular leakage and inhibited vascular EC proliferation, which eventually resulted in more severe inflammatory lung injury. In addition, siRNA-mediated knockdown of Cdc42 protein on ECs disrupted cell proliferation and migration and tube formation, which are necessary processes for recovery after inflammatory vascular injury, resulting in inflammatory vascular injury recovery defects.

Conclusion

We found that Cdc42 deficiency impairs EC function and regeneration, which are crucial in the post-inflammatory vascular injury repair process. These findings indicate that Cdc42 is a potential target for novel treatments designed to facilitate endothelial regeneration and vascular repair in inflammatory pulmonary vascular diseases, such as ALI/ARDS.

Electronic supplementary material

The online version of this article (10.1186/s12931-018-0729-8) contains supplementary material, which is available to authorized users.

Migration-inducing gene 7 promotes tumorigenesis and angiogenesis and independently predicts poor prognosis of epithelial ovarian cancer

Epithelial ovarian carcinomas (EOC) cause more mortality than any other cancer of the female reproductive system. New therapeutic approaches to reduce EOC mortality have been largely unsuccessful due to the poor understanding of the mechanisms underlying EOC proliferation and metastasis. Progress in EOC treatment is further hampered by a lack of reliable prognostic biomarkers for early risk assessment. In this study, we identify that Migration-Inducting Gene 7 (MIG-7) is specifically induced in human EOC tissues but not normal ovaries or ovarian cyst. Ovarian MIG-7 expression strongly correlated with EOC progression. Elevated MIG-7 level at the time of primary cytoreductive surgery was a strong and independent predictor of poor survival of EOC patients. Cell and murine xenograft models showed that MIG-7 was required for EOC proliferation and invasion, and MIG-7 enhanced EOC-associated angiogenesis by promoting the expression of vascular endothelial growth factor. Inhibiting MIG-7 by RNA interference in grafted EOC cells retarded tumor growth, angiogenesis and improved host survival, and suppressing MIG-7 expression with a small molecule inhibitor D-39 identified from the medicinal plant Liriope muscari mitigated EOC growth and invasion and specifically abrogated the expression of vascular endothelial growth factor. Our data not only reveal a critical function of MIG-7 in EOC growth and metastasis and support MIG-7 as an independent prognostic biomarker for EOC, but also demonstrate that therapeutic targeting of MIG-7 is likely beneficial in the treatment of EOC.

Tumorigenic proteins upregulated in the MYCN-amplified IMR-32 human neuroblastoma cells promote proliferation and migration

Childhood neuroblastoma is one of the most common types of extra-cranial cancer affecting children with a clinical spectrum ranging from spontaneous regression to malignant and fatal progression. In order to improve the clinical outcomes of children with high-risk neuroblastoma, it is crucial to understand the tumorigenic mechanisms that govern its malignant behaviors. MYCN proto-oncogene, bHLH transcription factor (MYCN) amplification has been implicated in the malignant, treatment-evasive nature of aggressive, high-risk neuroblastoma. In this study, we used a SILAC approach to compare the proteomic signatures of MYCN-amplified IMR-32 and non-MYCN-amplified SK-N-SH human neuroblastoma cells. Tumorigenic proteins, including fatty-acid binding protein 5 (FABP5), L1-cell adhesion molecule (L1-CAM), baculoviral IAP repeat containing 5 [BIRC5 (survivin)] and high mobility group protein A1 (HMGA1) were found to be significantly upregulated in the IMR-32 compared to the SK-N-SH cells and mapped to highly tumorigenic pathways including, MYC, MYCN, microtubule associated protein Tau (MAPT), E2F transcription factor 1 (E2F1), sterol regulatory element binding transcription factor 1 or 2 (SREBF1/2), hypoxia-inducible factor 1α (HIF-1α), Sp1 transcription factor (SP1) and amyloid precursor protein (APP). The transcriptional knockdown (KD) of MYCN, HMGA1, FABP5 and L1-CAM significantly abrogated the proliferation of the IMR-32 cells at 48 h post transfection. The early apoptotic rates were significantly higher in the IMR-32 cells in which FABP5 and MYCN were knocked down, whereas cellular migration was significantly abrogated with FABP5 and HMGA1 KD compared to the controls. Of note, L1-CAM, HMGA1 and FABP5 KD concomitantly downregulated MYCN protein expression and MYCN KD concomitantly downregulated L1-CAM, HMGA1 and FABP5 protein expression, while survivin protein expression was significantly downregulated by MYCN, HMGA1 and FABP5 KD. In addition, combined L1-CAM and FABP5 KD led to the concomitant downregulation of HMGA1 protein expression. On the whole, our data indicate that this inter-play between MYCN and the highly tumorigenic proteins which are upregulated in the malignant IMR-32 cells may be fueling their aggressive behavior, thereby signifying the importance of combination, multi-modality targeted therapy to eradicate this deadly childhood cancer.

miR-675-5p enhances tumorigenesis and metastasis of esophageal squamous cell carcinoma by targeting REPS2

Recently H19 has been demonstrated to be up-regulated in esophageal squamous cell carcinoma (ESCC) and shown to be the precursor of miR-675 that encodes miR-675-5p conservatively. miR-675 is overexpressed in many human cancers; however, the function of miR-675-5p is largely unknown in ESCC. In this study, we found that miR-675-5p expression was significantly increased in ESCC tissues and cell lines and related with ESCC progression and poor prognosis. We also showed here that down-regulation of miR-675-5p in ESCC cells dramatically induced cell G1 arrest and reduced cell proliferation, colony formation, migration and invasion in vitro as well as tumorigenesis and tumor metastasis in vivo. We subsequently identified that REPS2 was a target gene of miR-675-5p. We found that inhibition of miR-675-5p up-regulated the expression of REPS2, inhibited RalBP1/RAC1/CDC42 signaling pathway. Inversely, interference of REPS2 abrogated the effect induced by miR-675-5p inhibition, which resembled the function of miR-675-5p up-regulation. Taken together, our findings suggested that miR-675-5p might play an oncogenic role in ESCC through RalBP1/RAC1/CDC42 signaling pathway by inhibiting REPS2 and might serve as a valuable prognostic biomarker and therapeutic target for ESCC patients.

P-REX1 amplification promotes progression of cutaneous melanoma via the PAK1/P38/MMP-2 pathway

P-REX1 (PIP3-dependent Rac exchange factor-1) is a guanine nucleotide exchange factor that activates Rac by catalyzing exchange of GDP for GTP bound to Rac. Aberrant up-regulation of P-REX1 expression has a role in metastasis however, copy number (CN) and function of P-REX1 in cutaneous melanoma are unclear. To explore the role of P-REX1 in melanoma, SNP 6.0 and Exon 1.0 ST microarrays were assessed. There was a higher CN (2.82-fold change) of P-REX1 in melanoma cells than in melanocytes, and P-REX1 expression was significantly correlated with P-REX1 CN. When P-REX1 was knocked down in cells by P-REX1 shRNA, proliferation, colony formation, 3D matrigel growth, and migration/invasiveness were inhibited. Loss of P-REX1 inhibited cell proliferation by inhibiting cyclin D1, blocking cell cycle, and increased cell apoptosis by reducing expression of the protein survivin. Knockdown of P-REX1 expression inhibited cell migration/invasiveness by disrupting P-REX1/RAC1/PAK1/p38/MMP-2 pathway. Assessment of patient tumors and disease outcome demonstrated lower distant metastasis-free survival among AJCC stage I/II/III patients with high P-REX1 expression compared to patients with low P-REX1 expression. These results suggest P-REX1 plays an important role in tumor progression and a potential theranostic target.

Synergistic effect of collagenase-1 (MMP1), stromelysin-1 (MMP3) and gelatinase-B (MMP9) gene polymorphisms in breast cancer

Background

Extracellular matrix degradation by matrix metalloproteinases (MMPs) is an important mechanism involved in tumor invasion and metastasis. Genetic variations of MMPs have shown association with multiple cancers. The present study is focused to elucidate the association of MMP-1, 3 and 9 genetic variants with respect to epidemiological and clinicopathological variables by haplotype, LD, MDR, survival in silico analyses among South Indian women.

Material and methods

MMP3–1171 5A/6A and MMP9–1562 C/T SNPs were genotyped by Allele specific polymerase chain reaction and MMP1-1607 1G/2G polymorphism by restriction fragment length polymorphism assays respectively, in 300 BC patients and age-matched 300 healthy controls. Statistical analysis was performed using the SNPStats and SPSS software. Linkage disequilibrium and gene-gene interactions were performed using Haploview and MDR software respectively. Further, transcription factor binding sites in the promoter regions of SNPs under study were carried out using AliBaba2.1 software.

Results

We have observed an increased frequency of 2G-allele of MMP1, 6A-allele of MMP3 and T-allele of MMP9 (p<0.05) respectively in BC subjects. The 2G-6A haplotype (minor alleles of MMP-1 and MMP-3 respectively) has shown an increased susceptibility to BC. Further, MMP polymorphisms were associated with the clinical characteristics of BC patients such as steroid hormone receptor status, lymph node involvement and metastasis. SNP combinations were in perfect LD in controls. MDR analysis revealed a positive interaction between the SNPs. 5-years survival rate and cox-regression analysis showed a significant association with clinicopathological variables.

Conclusion

Our results suggest that MMP1–1607 1G/2G, MMP3–1171 5A/6A and MMP9–1562 C/T gene polymorphisms have synergistic effect on breast cancer. The interactions of MMPs clinical risk factors such as lymph node involvement has shown a strong correlation and might influence the 5-years survival rate, suggesting their potential role in the breast carcinogenesis.

EZH2-mediated epigenetic silencing of TIMP2 promotes ovarian cancer migration and invasion

Enhancer of zeste homolog 2 (EZH2) is often increased in malignant tumors and is involved in metastasis. EZH2 silences gene expression by tri-methylating the lysine 27 residue of histone H3 (H3K27me3). However, the mechanism underlying EZH2 promotion of ovarian cancer metastasis remains elusive. Here, we showed that EZH2 is up-regulated in ovarian cancer and is associated with tumor metastasis and poor survival by mRNA sequencing and microarray results from databases. Tissue microarray and immunohistochemistry results revealed that EZH2 was negatively correlated with the expression of tissue inhibitor of metalloproteinases 2 (TIMP2). EZH2 overexpression inhibited TIMP2 expression and promoted proteolytic activities of matrix metalloproteinases 2 and 9 and vice versa. EZH2 promoted ovarian cancer invasion and migration, which could be largely reversed by TIMP2 down-regulation in vitro and in vivo. Both H3K27me3 inhibition and demethylation could reduce methylation of the TIMP2 promoter and finally reactivate TIMP2 transcription. The presence of EZH2 and H3K27me3 at the TIMP2 promoter was confirmed by chromatin immunoprecipitation. H3K27me3 and DNA methyltransferases at the promoter were significantly increased by EZH2 overexpression. These results suggest that EZH2 inhibits TIMP2 expression via H3K27me3 and DNA methylation, which relieve the repression of MMP and facilitate ovarian cancer invasion and migration.

Relationship between matrix metalloproteinases and the occurrence and development of ovarian cancer

Ovarian cancer is one of the most malignant genital cancers, with a high mortality rate. Many researchers have suggested that matrix metalloproteinases (MMPs) have remarkably high expression in ovarian cancer tissues. MMPs are considered to be related to the occurrence, development, invasion and metastasis of ovarian cancer. Moreover, some studies have discovered that the unbalance between MMPs and tissue inhibitor of metalloproteinases (TIMPs) are associated with the malignant phenotype of tumors. This review summarizes the latest research progress of MMPs in ovarian cancer. The investigation of MMP mechanism in ovarian cancer will facilitate the development of effective anti-tumor drugs, and thereby improve the survival rate of patients with ovarian cancer.

Exosomal miR-940 maintains SRC-mediated oncogenic activity in cancer cells: a possible role for exosomal disposal of tumor suppressor miRNAs

Exosomes have emerged as important mediators of diverse biological functions including tumor suppression, tumor progression, invasion, immune escape and cell-to-cell communication, through the release of molecules such as mRNAs, miRNAs, and proteins. Here, we identified differentially expressed exosomal miRNAs between normal epithelial ovarian cell line and both resistant and sensitive ovarian cancer (OC) cell lines. We found miR-940 as abundant in exosomes from SKOV3-IP1, HeyA8, and HeyA8-MDR cells. The high expression of miR-940 is associated with better survival in patients with ovarian serous cystadenocarcinoma. Ectopic expression of miR-940 inhibited proliferation, colony formation, invasion, and migration and triggered G0/G1 cell cycle arrest and apoptosis in OC cells. Overexpression of miR-940 also inhibited tumor cell growth in vivo. We showed that proto-oncogene tyrosine-protein kinase (SRC) is directly targeted by miR-940 and that miR-940 inhibited SRC expression at mRNA and protein levels. Following this inhibition, the expression of proteins downstream of SRC, such as FAK, paxillin and Akt was also reduced. Collectively, our results suggest that OC cells secrete the tumor-suppressive miR-940 into the extracellular environment via exosomes, to maintain their invasiveness and tumorigenic phenotype.

Introducing crucial protein panel of gastric adenocarcinoma disease

AIM

Since interactome analysis of diseases can provide candidate biomarker panel related to the diseases, in this research, protein-protein interaction (PPI) network analysis is used to introduce the involved crucial proteins in Gastric adenocarcinoma (GA).

BACKGROUND

Gastric adenocarcinoma (GA) is the most common type of stomach cancer. There is no efficient diagnostic molecular method for GA.

METHOD

Applying Cytoscape software 3.4.0 and String Database, the PPI network was constructed for 200 genes. Based on centrality parameters, the critical nodes were screened. Gene ontology of the key proteins for pathway analysis and molecular function processing were done and the highlighted pathways and activities were discussed.

RESULTS

Among 200 initial genes, 141 genes were included in a main connected network. Seven crucial proteins, including tumor protein p53, epidermal growth factor receptor, albumin, v-erb-b2 erythroblastic leukemia viral oncogene homolog 2, neuro/glioblastoma derived oncogene homolog (avian), v-akt murine thymoma viral oncogene homolog 1, v-src sarcoma (Schmidt-Ruppin A-2) viral oncogene homolog (avian) and catenin (cadherin-associated protein), beta 1, 88kDa, and Myogenic differentiation 1, were introduced as key nodes of the network. These identified proteins are mostly involved in pathways and activities related to cancer.

CONCLUSION

In conclusion, the finding is corresponding to the significant roles of these introduced proteins in GA disease. This protein panel may be a useful probe in the management of GA.

MIIP remodels Rac1-mediated cytoskeleton structure in suppression of endometrial cancer metastasis

BACKGROUND

Endometrial carcinoma (EC) is one of the most common malignancies of the female reproductive system. Migration and invasion inhibitory protein (MIIP) gene was recently discovered candidate tumor suppress gene which located at chromosome 1p36.22. 1p36 deletion was found in many types of tumor including EC. In the present study, we will determine the role and mechanism of MIIP in EC metastasis.

METHODS

Immunohistochemistry was used to measure MIIP expression in normal and EC tissue. Both gain-of-function (infection) and loss-of-function (siRNA) assays were used to alter MIIP expression levels. The effect of MIIP on cell migration and invasion was measured by transwell assay. F-actin immunofluorescence staining was used to observe the cell morphology. The activation of GTP-loaded Rac1 was evaluated by Rac activity assay kit. Immunoprecipitation/WB was used to measure the interaction between MIIP and PAK1.

RESULTS

We demonstrate that MIIP expression was significantly decreased in EC patients comparing to the normal ones, and decreased MIIP expression in EC tissues is associated with deep myometrial invasion, advanced stage, and the presence of lymph node metastasis. Using both gain-of-function (infection) and loss-of-function (siRNA) assays, we show that MIIP markedly blocked EC cell migration, whereas loss of MIIP led to increase in EC cell migration. We demonstrate that elevated expression of MIIP resulted in cytoskeleton reorganization with decreased formation of lamellipodia. We also provide evidence that MIIP is a key molecule in directing Rac1 signaling cascades in EC. Ectopically expressed MIIP consistently competed with Rac1-GTP for binding with the PAK1 p21-binding domain. Our data show that MIIP and PAK1 bind each other and that a C-terminal polyproline domain of MIIP is required for PAK1 binding. Deletion of the PAK1-binding domain of MIIP reduced cell migration-inhibiting activity.

CONCLUSIONS

MIIP may function as a tumor suppressor gene for endometrial carcinoma. MIIP attenuates Rac1 signaling through a protein interaction network, and loss of this regulator may contribute to EC metastasis.

Novel Axl-driven signaling pathway and molecular signature characterize high-grade ovarian cancer patients with poor clinical outcome

High-grade epithelial ovarian cancer (HGEOC) is a clinically diverse and molecularly heterogeneous disease comprising subtypes with distinct biological features and outcomes. The receptor tyrosine kinases, expressed by EOC cells, and their ligands, present in the microenvironment, activate signaling pathways, which promote EOC cells dissemination. Herein, we established a molecular link between the presence of Gas6 ligand in the ascites of HGEOCs, the expression and activation of its receptor Axl in ovarian cancer cell lines and biopsies, and the progression of these tumors. We demonstrated that Gas6/Axl signalling converges on the integrin β3 pathway in the presence of the adaptor protein p130Cas, thus inducing tumor cell adhesion to the extracellular matrix and invasion. Accordingly, Axl and p130Cas were significantly co-expressed in HGEOC samples. Clinically, we identified an Axl-associated signature of 62 genes able to portray the HGEOCs with the shortest overall survival. These data biologically characterize a group of HGEOCs and could help guide a more effective therapeutic approach to be taken for these patients.

Activation of Epidermal Growth Factor Receptor/p38/Hypoxia-inducible Factor-1α Is Pivotal for Angiogenesis and Tumorigenesis of Malignantly Transformed Cells Induced by Hexavalent Chromium

Hexavalent chromium (Cr(VI))-containing compounds are well established environmental carcinogens. Most mechanistic investigations of Cr(VI)-induced carcinogenesis focus on oxidative stress and various cellular responses, leading to malignant cell transformation or the first stage of metal-induced carcinogenesis. The development of malignantly transformed cells into tumors that require angiogenesis is the second stage. This study focuses on the second stage, in particular, the role of EGF receptor (EGFR) signaling in angiogenesis and tumorigenesis of Cr(VI)-transformed cells. Our preliminary studies have shown that EGFR is constitutively activated in Cr(VI)-transformed cells, in lung tissue from Cr(VI)-exposed animals, and in lung tumor tissue from a non-smoking worker occupationally exposed to Cr(VI) for 19 years. Using in vitro and in vivo models, the present study has investigated the role of EGFR in angiogenesis of Cr(VI)-transformed cells. The results show that Cr(VI)-transformed cells are angiogenic. Hypoxia-inducible factor-1α, pro-angiogenic protein matrix metalloproteinase 1, and VEGF are all highly expressed in Cr(VI)-transformed cells, in lung tissue from animals exposed to Cr(VI), and in lung tumor tissue from a non-smoking worker occupationally exposed to Cr(VI) for 19 years. p38 MAPK is also activated in Cr(VI)-transformed cells and in human lung tumor tissue. Inhibition of EGFR reduces p38 MAPK, resulting in decreased expression of hypoxia-inducible factor-1α, metalloproteinase 1, and VEGF, leading to suppressions of angiogenesis and tumorigenesis. Overall, the present study has demonstrated that EGFR plays an important role in angiogenesis and tumorigenesis of Cr(VI)-transformed cells.

MicroRNA-195a-3p inhibits angiogenesis by targeting Mmp2 in murine mesenchymal stem cells

MicroRNAs (miRNAs) modulate complex physiological and pathological processes, including the regulation of angiogenesis. Our previous study reported that bone marrow-derived mesenchymal stem cells (MSCs) are recruited into choroidal neovascularization lesions. miRNA-195 is highly expressed in MSCs, but its function remains unknown. In the present study, miR-195a-3p abundance was significantly decreased in hypoxia-treated murine MSCs; on the other hand, its overexpression reduced MSC proliferation and migration while increasing the activation of anti-angiogenic factor pigment epithelium-derived factor (PEDF). We further discovered that matrix metalloproteinase 2 (Mmp2) transcript is a target of miR-195a-3p, and that silencing Mmp2 phenocopied the reduced proliferation and migration of MSCs. The therapeutic potential of miR-195a-3p as an angiogenesis inhibitor was also demonstrated in a laser-induced choroidal neovascularization mouse model. These findings collectively indicate that miR-195a-3p is a negative modulator of angiogenesis, and could be used as an angiogenesis inhibitor. Mol. Reprod. Dev. 83: 413-423, 2016. © 2016 Wiley Periodicals, Inc.

PAKs in Human Cancer Progression: From Inception to Cancer Therapeutic to Future Oncobiology

Since the initial recognition of a mechanistic role of p21-activated kinase 1 (PAK1) in breast cancer invasion, PAK1 has emerged as one of the widely overexpressed or hyperactivated kinases in human cancer at-large, allowing the PAK family to make in-roads in cancer biology, tumorigenesis, and cancer therapeutics. Much of our current understanding of the PAK family in cancer progression relates to a central role of the PAK family in the integration of cancer-promoting signals from cell membrane receptors as well as function as a key nexus-modifier of complex, cytoplasmic signaling network. Another core aspect of PAK signaling that highlights its importance in cancer progression is through PAK's central role in the cross talk with signaling and interacting proteins, as well as PAK's position as a key player in the phosphorylation of effector substrates to engage downstream components that ultimately leads to the development cancerous phenotypes. Here we provide a comprehensive review of the recent advances in PAK cancer research and its downstream substrates in the context of invasion, nuclear signaling and localization, gene expression, and DNA damage response. We discuss how a deeper understanding of PAK1's pathobiology over the years has widened research interest to the PAK family and human cancer, and positioning the PAK family as a promising cancer therapeutic target either alone or in combination with other therapies. With many landmark findings and leaps in the progress of PAK cancer research since the infancy of this field nearly 20 years ago, we also discuss postulated advances in the coming decade as the PAK family continues to shape the future of oncobiology.

Clinicopathological significance of p38β, p38γ, and p38δ and its biological roles in esophageal squamous cell carcinoma

P38β, p38γ, and p38δ have been sporadically and scarcely reported to be involved in the carcinogenesis of cancers, compared with p38α isoform. However, little has been known regarding their clinicopathological significance and biological roles in esophageal squamous cell carcinoma (ESCC). Expression status of p38β, p38γ, and p38δ was assayed using immunohistochemistry with ESCC tissue microarray; ensuing clinicopathological significance was statistically analyzed. To define its biological roles on proliferation, migration and invasion of ESCC cell line Eca109 in vitro, MTT, wound healing, and Transwell assays were employed, respectively. As confirmation, athymic nude mice were taken to verify the effect over proliferation in vivo. It was found that both p38β and p38δ expression, other than p38γ, were significantly higher in ESCC tissues compared with paired normal controls. In terms of prognosis, only p38β expression was observed to be significantly associated with overall prognosis. Clinicopathologically, there was significant association between p38γ expression and clinical stage, lymph nodes metastases, and tumor volume. No significant association was found for p38β and p38δ between its expression and other clinicopathological parameters other than significant difference of expression between ESCC versus normal control. In Eca109, it was observed that p38β, p38γ, and p38δ can promote the cell growth and motility. As verification, over-expression of p38δ can promote, whereas knockdown of p38γ can prevent, the tumorigenesis in nude mice model xenografted with Eca109 cells whose basal level of p38δ was stably over-expressed and p38γ was stably knocked down. Together, our results demonstrate that p38β, p38γ, and p38δ played oncogenic roles in ESCC.

Bisphosphonates for cancer treatment: Mechanisms of action and lessons from clinical trials

A growing body of evidence points toward an important anti-cancer effect of bisphosphonates, a group of inexpensive, safe, potent, and long-term stable pharmacologicals that are widely used as osteoporosis drugs. To date, they are already used in the prevention of complications of bone metastases. Because the bisphosphonates can also reduce mortality in among other multiple myeloma, breast, and prostate cancer patients, they are now thoroughly studied in oncology. In particular, the more potent nitrogen-containing bisphosphonates have the potential to improve prognosis. The first part of this review will elaborate on the direct and indirect anti-tumoral effects of bisphosphonates, including induction of tumor cell apoptosis, inhibition of tumor cell adhesion and invasion, anti-angiogenesis, synergism with anti-neoplastic drugs, and enhancement of immune surveillance (e.g., through activation of γδ T cells and targeting macrophages). In the second part, we shed light on the current clinical position of bisphosphonates in the treatment of hematological and solid malignancies, as well as on ongoing and completed clinical trials investigating the therapeutic effect of bisphosphonates in cancer. Based on these recent data, the role of bisphosphonates is expected to further expand in the near future outside the field of osteoporosis and to open up new avenues in the treatment of malignancies.