Intracellular modifiers of integrin alpha 6p production in aggressive prostate and breast cancer cell lines

Remodeling of the extracellular matrix by serine proteases as a prerequisite for cancer initiation and progression

The extracellular matrix (ECM) serves as a physical scaffold for tissues that is composed of structural proteins such as laminins, collagens, proteoglycans and fibronectin, forming a three dimensional network, and a wide variety of other matrix proteins with ECM-remodeling and signaling functions. The activity of ECM-associated signaling proteins is tightly regulated. Thus, the ECM serves as a reservoir for water and growth regulatory signals. The ECM architecture is dynamically modulated by multiple serine proteases that process both structural and signaling proteins to regulate physiological processes such as organogenesis and tissue homeostasis but they also contribute to pathological events, especially cancer progression. Here, we review the current literature regarding the role of ECM remodeling by serine proteases (KLKs, uPA, furin, HtrAs, granzymes, matriptase, hepsin) in tumorigenesis.

Biophysical phenotype mixtures reveal advantages for tumor muscle invasion in vivo

Bladder, colon, gastric, prostate, and uterine cancers originate in organs surrounded by laminin-coated smooth muscle. In human prostate cancer, tumors that are organ confined, without extracapsular extension through muscle, have an overall cancer survival rate of up to 97% compared with 32% for metastatic disease. Our previous work modeling extracapsular extension reported the blocking of tumor invasion by mutation of a laminin-binding integrin called α6β1. Expression of the α6AA mutant resulted in a biophysical switch from cell-ECM (extracellular matrix) to cell-cell adhesion with drug sensitivity properties and an inability to invade muscle. Here we used different admixtures of α6AA and α6WT cells to test the cell heterogeneity requirements for muscle invasion. Time-lapse video microscopy revealed that tumor mixtures self-assembled into invasive networks in vitro, whereas α6AA cells assembled only as cohesive clusters. Invasion of α6AA cells into and through live muscle occurred using a 1:1 mixture of α6AA and α6WT cells. Electric cell-substrate impedance sensing measurements revealed that compared with α6AA cells, invasion-competent α6WT cells were 2.5-fold faster at closing a cell-ECM or cell-cell wound, respectively. Cell-ECM rebuilding kinetics show that an increased response occurred in mixtures since the response was eightfold greater compared with populations containing only one cell type. A synthetic cell adhesion cyclic peptide called MTI-101 completely blocked electric cell-substrate impedance sensing cell-ECM wound recovery that persisted in vitro up to 20 h after the wound. Treatment of tumor-bearing animals with 10 mg/kg MTI-101 weekly resulted in a fourfold decrease of muscle invasion by tumor and a decrease of the depth of invasion into muscle comparable to the α6AA cells. Taken together, these data suggest that mixed biophysical phenotypes of tumor cells within a population can provide functional advantages for tumor invasion into and through muscle that can be potentially inhibited by a synthetic cell adhesion molecule.

The hop-derived prenylflavonoid isoxanthohumol inhibits the formation of lung metastasis in B16-F10 murine melanoma model

Isoxanthohumol (IXN), a prenylflavonoid from hops and beer, gained increasing attention as a potential chemopreventive agent. In the present study, IXN antimetastatic potential in vitro against the highly invasive melanoma cell line B16-F10 and in vivo in a murine metastatic model was investigated. Melanoma cell viability was diminished in a dose-dependent manner following the treatment with IXN. This decrease was a consequence of autophagy and caspase-dependent apoptosis. Additionally, the dividing potential of highly proliferative melanoma cells was dramatically affected by this isoflavanone, which was in correlation with an abrogated cell colony forming potential, indicating changes in their metastatic features. Concordantly, IXN promoted strong suppression of the processes that define metastasis- cell adhesion, invasion, and migration. Further investigation at the molecular level revealed that the abolished metastatic potential of a melanoma subclone was due to disrupted integrin signaling. Importantly, these results were reaffirmed in vivo where IXN inhibited the development of lung metastatic foci in tumor-challenged animals. The results of the present study may highlight the beneficial effects of IXN on melanoma as the most aggressive type of skin cancer and will hopefully shed a light on the possible use of this prenylflavonoid in the treatment of metastatic malignancies.

ITGA6 and RPSA synergistically promote pancreatic cancer invasion and metastasis via PI3K and MAPK signaling pathways

Pancreatic cancer is one of the most malignant tumors. Invasion and metastasis can occur in the early stage of pancreatic cancer, contributing to the poor prognosis. Accordingly, in this study, we evaluated the molecular mechanisms underlying invasion and metastasis. Using mass spectrometry, we found that Integrin alpha 6 (ITGA6) was more highly expressed in a highly invasive pancreatic cancer cell line (PC-1.0) than in a less invasive cell line (PC-1). Through in vitro and in vivo experiments, we observed significant decreases in invasion and metastasis in pancreatic cancer cells after inhibiting ITGA6. Based on data in TCGA, high ITGA6 expression significantly predicted poor prognosis. By using Co-IP combined mass spectrometry, we found that ribosomal protein SA (RPSA), which was also highly expressed in PC-1.0, interacted with ITGA6. Similar to ITGA6, high RPSA expression promoted invasion and metastasis and indicated poor prognosis. Interestingly, although ITGA6 and RPSA interacted, they did not mutually regulate each other. ITGA6 and RPSA affected invasion and metastasis via the PI3K and MAPK signaling pathways, respectively. Inhibiting ITGA6 significantly reduced the expression of p-AKT, while inhibiting RPSA led to the downregulation of p-ERK1/2. Compared with the inhibition of ITGA6 or RPSA alone, the downregulation of both ITGA6 and RPSA weakened invasion and metastasis to a greater extent and led to the simultaneous downregulation of p-AKT and p-ERK1/2. Our research indicates that the development of drugs targeting both ITGA6 and RPSA may be an effective strategy for the treatment of pancreatic cancer.

Live-cell phenotypic-biomarker microfluidic assay for the risk stratification of cancer patients via machine learning

The risk stratification of prostate cancer and breast cancer tumours from patients relies on histopathology, selective genomic testing, or on other methods employing fixed formalin tissue samples. However, static biomarker measurements from bulk fixed-tissue samples provide limited accuracy and actionability. Here, we report the development of a live-primary-cell phenotypic-biomarker assay with single-cell resolution, and its validation with prostate cancer and breast cancer tissue samples for the prediction of post-surgical adverse pathology. The assay includes a collagen-I/fibronectin extracellular-matrix formulation, dynamic live-cell biomarkers, a microfluidic device, machine-vision analysis and machine-learning algorithms, and generates predictive scores of adverse pathology at the time of surgery. Predictive scores for the risk stratification of 59 prostate cancer patients and 47 breast cancer patients, with values for area under the curve in receiver-operating-characteristic curves surpassing 80%, support the validation of the assay and its potential clinical applicability for the risk stratification of cancer patients.

Cancer Stem Cell Metabolism and Potential Therapeutic Targets

Malignant tumors contain heterogeneous populations of cells in various states of proliferation and differentiation. The presence of cancer stem or initiating cells is a well-established concept wherein quiescent and poorly differentiated cells within a tumor mass contribute to drug resistance, and under permissive conditions, are responsible for tumor recurrence and metastasis. A number of studies have identified molecular markers that are characteristic of tissue-specific cancer stem cells (CSCs). Isolation of CSCs has enabled studies on the metabolic status of CSCs. As metabolic plasticity is a hallmark of cancer cell adaptation, the intricacies of CSC metabolism and their phenotypic behavior are critical areas of research. Unlike normal stem cells, which rely heavily on oxidative phosphorylation (OXPHOS) as their primary source of energy, or cancer cells, which are primarily glycolytic, CSCs demonstrate a unique metabolic flexibility. CSCs can switch between OXPHOS and glycolysis in the presence of oxygen to maintain homeostasis and, thereby, promote tumor growth. Here, we review key factors that impact CSC metabolic phenotype including heterogeneity of CSCs across different histologic tumor types, tissue-specific variations, tumor microenvironment, and CSC niche. Furthermore, we discuss how targeting key players of glycolytic and mitochondrial pathways has shown promising results in cancer eradication and attenuation of disease recurrence in preclinical models. In addition, we highlight studies on other potential therapeutic targets including complex interactions within the microenvironment and cellular communications in the CSC niche to interfere with CSC growth, resistance, and metastasis.

PSMC2 is up-regulated in osteosarcoma and regulates osteosarcoma cell proliferation, apoptosis and migration

Proteasome 26S subunit ATPase 2 (PSMC2) is a recently identified gene potentially associated with certain human carcinogenesis. However, the expressional correlation and functional importance of PSMC2 in osteosarcoma is still unclear. Current study was focused on elucidating the significance of PSMC2 on malignant behaviors in osteosarcoma including proliferation, apoptosis, colony formation, migration as well as invasion. The high protein levels of PSMC2 in osteosarcoma samples were identified by tissue microarrays analysis. Besides, its expression in the levels of mRNA and protein was also detected in four different osteosarcoma cell lines by real-time PCR and western blotting separately. Silencing PSMC2 by RNA interference in osteosarcoma cell lines (SaoS-2 and MG-63) would significantly suppress cell proliferation, enhance apoptosis, accelerate G2/M phase and/or S phase arrest, and decrease single cell colony formation. Similarly, pharmaceutical inhibition of proteasome with MG132 would mimic the PSMC2 depletion induced defects in cell cycle arrest, apoptosis and colonies formation. Silencing of PSMC2 was able to inhibit osteosarcoma cell motility, invasion as well as tumorigenicity in nude mice. Moreover, the gene microarray indicated knockdown of PSMC2 notably changed a number of genes, especially some cancer related genes including ITGA6, FN1, CCND1, CCNE2 and TGFβR2, and whose expression changes were further confirmed by western blotting. Our data suggested that PSMC2 may work as an oncogene for osteosarcoma and that inhibition of PSMC2 may be a therapeutic strategy for osteosarcoma treatment.

Penfluridol Represses Integrin Expression in Breast Cancer through Induction of Reactive Oxygen Species and Downregulation of Sp Transcription Factors

It was recently demonstrated the penfluridol inhibited breast tumor growth and metastasis and this was associated with downregulation of α6- and β4-integrins. In this study, we observed the penfluridol induced reactive oxygen species (ROS) and this was the primary mechanism of action. Penfluridol-mediated growth inhibition, induction of apoptosis, and inhibition of breast cancer cell migration was attenuated after cotreatment with glutathione. Penfluridol also downregulated Sp transcription factors Sp1, Sp3, and Sp4 through epigenetic downregulation of cMyc and cMyc-regulated miRNAs (miR27a and miR20a/miR17) and induction of the miR-regulated Sp transcriptional repressors ZBTB10 and ZBTB4. α6- and β4-integrins as well as α5- and β1-integrins are Sp-regulated genes that are also coregulated by the orphan nuclear receptor NR4A1 and these integrins can be targeted by agents such as penfluridol that suppress Sp1, Sp3, and Sp4 and also by NR4A1 antagonists. Mol Cancer Ther; 16(1); 205-16. ©2016 AACR.

Potential Roles of Protease Inhibitors in Cancer Progression

Proteases are important molecules that are involved in many key physiological processes. Protease signaling pathways are strictly controlled, and disorders in protease activity can result in pathological changes such as cardiovascular and inflammatory diseases, cancer and neurological disorders. Many proteases have been associated with increasing tumor metastasis in various human cancers, suggesting important functional roles in the metastatic process because of their ability to degrade the extracellular matrix barrier. Proteases are also capable of cleaving non-extracellular matrix molecules. Inhibitors of proteases to some extent can reduce invasion and metastasis of cancer cells, and slow down cancer progression. In this review, we focus on the role of a few proteases and their inhibitors in tumors as a basis for cancer prognostication and therapy.

Laminin-binding integrin gene copy number alterations in distinct epithelial-type cancers

BACKGROUND

The laminin-binding integrin (LBI) family are cell adhesion molecules that are essential for invasion and metastasis of human epithelial cancers and cell adhesion mediated drug resistance. We investigated whether copy number alteration (CNA) or mutations of a five-gene signature (ITGB4, ITGA3, LAMB3, PLEC, and SYNE3), representing essential genes for LBI adhesion, would correlate with patient outcomes within human epithelial-type tumor data sets currently available in an open access format.

METHODS

We investigated the relative alteration frequency of an LBI signature panel (integrin β4 (ITGB4), integrin α3 (ITGA3), laminin β3 chain (LAMB3), plectin (PLEC), and nesprin 3 (SYNE3)), independent of the epithelial cancer type, within publically available and published data using cBioPortal and Oncomine software. We rank ordered the results using a 20% alteration frequency cut-off and limited the analysis to studies containing at least 100 samples. Kaplan-Meier survival curves were analyzed to determine if alterations in the LBI signature correlated with patient survival. The Oncomine data mining tool was used to compare the heat map expression of the LBI signature without SYNE3 (as this was not included in the Oncomine database) to drug resistance patterns.

RESULTS

Twelve different cancer types, representing 5,647 samples, contained at least a 20% alteration frequency of the five-gene LBI signature. The frequency of alteration ranged from 38.3% to 19.8%. Within the LBI signature, PLEC was the most commonly altered followed by LAMB3, ITGB4, ITGA3, and SYNE3 across all twelve cancer types. Within cancer types, there was little overlap of the individual amplified genes from each sample, suggesting different specific amplicons may alter the LBI adhesion structures. Of the twelve cancer types, overall survival was altered by CNA presence in bladder urothelial carcinoma (p=0.0143*) and cervical squamous cell carcinoma and endocervical adenocarcinoma (p=0.0432*). Querying the in vitro drug resistance profiles with the LBI signature demonstrated a positive correlation with cells resistant to inhibitors of HDAC (Vorinostat, Panobinostat) and topoisomerase II (Irinotecan). No correlation was found with the following agents: Bleomycin, Doxorubicin, Methotrexate, Gemcitabine, Docetaxel, Bortezomib, and Shikonen.

CONCLUSIONS

Our work has identified epithelial-types of human cancer that have significant CNA in our selected five-gene signature, which was based on the essential and genetically-defined functions of the protein product networks (in this case, the LBI axis). CNA of the gene signature not only predicted overall survival in bladder, cervical, and endocervical adenocarcinoma but also response to chemotherapy. This work suggests that future studies designed to optimize the gene signature are warranted.

GENERAL SIGNIFICANCE

The copy number alteration of structural components of the LBI axis in epithelial-type tumors may be promising biomarkers and rational targets for personalized therapy in preventing or arresting metastatic spread.

CD49f promotes proliferation of male dairy goat germline stem cells

OBJECTIVES

CD49f enhances multipotency and maintains stemness in embryonic stem cells (ESCs), however, whether it would be effective in mGSCs has remained unclear. Moreover, better standards for mGSC enrichment and purification are necessary. The present study was conducted to determine roles of CD49f in mGSC enrichment and regulation.

MATERIALS AND METHODS

CD49f expression patterns were investigated in dairy goats. CD49f positive cells were purified and enriched using magnetic-activated cell sorting (MACS), and characteristics of the cultured cells were assayed using alkaline phosphatase (AP) analysis, quantitative real-time PCR (QRT-PCR) and immunofluorescence analysis. Furthermore, the exogenous CD49f gene was transfected into mGSCs and its effects were analysed.

RESULTS

CD49f was found to be conserved in both mRNA and amino acid sequences and that it was an efficient marker for dairy goat mGSC identification, enrichment and purification. CD49f positive cells expressed higher levels of mGSC-specific markers, and proliferated faster than CD49f negative cells. Overexpression CD49f promoted proliferation of dairy goat mGSCs, and Oct4 expression was upregulated; histone H3-lysine 9 dimethylation (H3K9me2) was reduced.

CONCLUSIONS

Taken together, our data suggest that CD49f plays novel and dynamic roles in regulating maintenance of pluripotency in mGSCs via Oct4 crosstalk and histone methylation dynamics,which may provide new solutions for mGSCs stability in vitro.

A combination of desmopressin and docetaxel inhibit cell proliferation and invasion mediated by urokinase-type plasminogen activator (uPA) in human prostate cancer cells

BACKGROUND

This study was designed to assess the effectiveness of a combination treatment using both desmopressin and docetaxel in prostate cancer treatment. Desmopressin is a well-known synthetic analogue of the antidiuretic hormone vasopressin. It has recently been demonstrated to inhibit tumor progression and metastasis in in vivo models. Docetaxel is widely used for the treatment of castration resistant prostate cancer (CRPC) patients. However, durable responses have been uncommon to date. In this study, we investigated the anti-tumor effect of desmopressin in combination with docetaxel in vitro and in vivo.

METHODS

Two prostate cancer cells (PC3, LNCaP) were treated with different concentrations of desmopressin alone, docetaxel alone, and a combination of desmopressin and docetaxel. Cell proliferation was determined by MTS assay. The anti-invasive and anti-migration potential of desmopressin and in combination with docetaxel were examined by wound healing assay, migration chamber assay, and matrigel invasion assay.

RESULTS

The combination of desmopressin and docetaxel resulted in a significant inhibition of PC3 and LNCaP cell proliferation (p < 0.01). Additionally, cell migration and invasion were also inhibited by the combination when compared to that of either treatment alone in PC3 cells (p < 0.01). The anti-tumor effect of this combination treatment was associated with down-regulation of both urokinase-type plasminogen activator (uPA) and matrix metalloproteinase (MMP-2 and MMP-9) in PC3 cells.

CONCLUSIONS

We are the first to elucidate the anti-tumor and anti-metastatic potential of desmopressin in combination with docetaxel in a prostate cancer model via the uPA-MMP pathway. Our finding could potentially contribute to the therapeutic profile of desmopressin and enhance the efficacy of docetaxel based treatment for CRPC.