PC3 prostate tumor-initiating cells with molecular profile FAM65Bhigh/MFI2low/LEF1low increase tumor angiogenesis

Inhibition of LATS kinases reduces tumorigenicity and increases the sensitivity of human chronic myelogenous leukemia cells to imatinib

Chronic myelogenous leukemia (CML) is a clonal hematologic malignancy of the myeloid lineage caused by the oncogenic BCR/ABL fusion protein that promotes CML cell proliferation and protects them against drug-induced apoptosis. In this study, we determine LATS1 and LATS2 expression in CML cells derived from patients who are resistant to imatinib (IM) treatment. Significant upregulation of LATS1 and LATS2 was found in these CML patients compared to healthy donors. To further explore whether the expression of LATS1/2 contributes to the IM-resistant phenotype, IM-resistant CML cell lines generated by culturing CML-derived erythroblastic K562 cells in increasing concentrations of IM were used as in vitro models. Up-regulation of LATS1 and LATS2 was observed in IM-resistant K562 cells. Reduction of LATS using either Lats-IN-1 (TRULI), a specific LATS inhibitor, or shRNA targeting LATS1/2 significantly reduced clonogenicity, increased apoptosis and induced differentiation of K562 cells to late-stage erythroid cells. Furthermore, depletion of LATS1 and LATS2 also increased the sensitivity of K562 cells to IM. Taken together, our results suggest that LATS could be one of the key factors contributing to the rapid proliferation, reduced apoptosis, and IM resistance of CML cells. Targeting LATS could be a promising treatment to enhance the therapeutic effect of a conventional BCR/ABL tyrosine kinase inhibitor such as IM.

A bis-quinoline ruthenium(II) arene complex with submicromolar cytotoxicity in castration-resistant prostate cancer cells

A new Ru(II) arene chlorido organometallic complex [(η6-p-cymene)(L)RuCl]PF6 (named as pCYRuL) using 2-bis(quinolin-2-ylmethylene) hydrazine (L) was developed that exhibits potent anticancer activity against castration-resistant prostate cancer (CRPC) (IC50 = 0.71 μM), and it is 45 times more effective than the standard drug cisplatin (IC50 = 31.3 μM) in a castration-resistant human prostatic adenocarcinoma cell line (PC-3) but non-toxic in normal human kidney cells (HK2) as well as normal breast cells (MCF10A) and found that pCYRuL exerted anticancer activity via apoptosis induction and cell cycle arrest in the G2/M phase of PC-3 cells.

Histone methyltransferase SUV39H2 regulates apoptosis and chemosensitivity in prostate cancer through AKT/FOXO signaling pathway

Prostate cancer (PCa) is one of the most common malignant tumors that exhibit both chemoresistance and recurrence. SUV39H2 is highly expressed in many types of human tumors, but its role in the development and progression of PCa has never been clarified. The aim of this study is to elucidate the role of SUV39H2 in the development and progression of PCa, its association with the AKT/FOXO signaling pathway, and its potential implications for PCa diagnosis and treatment. SUV39H2 expression was analyzed in The Cancer Genome Atlas (TCGA) and genotype tissue expression pan-cancer data. The TCGA database was evaluated for SUV39H2 enrichment and its correlation to immune cell infiltration. SUV39H2 levels in PCa tissues and control tissues were determined in 30 patients using qPCR and IHC. Clinical relevance was assessed via The Cancer Genome Atlas (TCGA). In vitro assessments including colony formation assays, Western Blot analysis, CCK-8 assays, and flow cytometry were utilized to establish SUV39H2's contribution to PCa cell growth. The influence of SUV39H2 on PC3 and DU145 cell proliferation was assessed through a cell line-derived xenograft model. Sphere formation assays and qPCR were employed to delineate SUV39H2's role in PCa stemness and chemosensitivity. In vitro macrophage polarization assays provided insights into SUV39H2's association with M2 macrophages, while enrichment analysis shed light on its role in FOXO signaling. PCa tissues expressed higher levels of SUV39H2 than normal tissues. By knocking down SUV39H2, PCa cells were made more chemosensitive to docetaxel and cell proliferation and stemness were inhibited. Additionally, SUV39H2 knockdown significantly inhibited in vivo PCa cell growth and inhibited the polarization of macrophages. Furthermore, SUV39H2 was found to regulate AKT/FOXO signaling by increasing Akt and FOXO3a phosphorylation. Our findings highlight SUV39H2's role in PCa cell apoptosis and chemosensitivity mainly by regulating the AKT/FOXO signaling pathway and suggest that SUV39H2 could be a potential target for PCa diagnosis and treatment.

RIPOR2 Expression Decreased by HPV-16 E6 and E7 Oncoproteins: An Opportunity in the Search for Prognostic Biomarkers in Cervical Cancer

High-risk human papillomavirus (HPV) infection is the main risk factor for cervical cancer (CC) development, where the continuous expression of E6 and E7 oncoproteins maintain the malignant phenotype. In Mexico, around 70% of CC cases are diagnosed in advanced stages, impacting the survival of patients. The aim of this work was to identify biomarkers affected by HPV-16 E6 and E7 oncoproteins that impact the prognosis of CC patients. Expression profiles dependent on E6 and E7 oncoproteins, as well as their relationship with biological processes and cellular signaling pathways, were analyzed in CC cells. A comparison among expression profiles of E6- and E7-expressing cells and that from a CC cohort obtained from The Cancer Genome Atlas (TCGA) demonstrated that the expression of 13 genes impacts the overall survival (OS). A multivariate analysis revealed that the downregulated expression of RIPOR2 was strongly associated with a worse OS. RIPOR2, including its transcriptional variants, were overwhelmingly depleted in E6- and E7-expressing cells. Finally, in a Mexican cohort, it was found that in premalignant cervical lesions, RIPOR2 expression decreases as the lesions progress; meanwhile, decreased RIPOR2 expression was also associated with a worse OS in CC patients.

Direct cell-cell interaction regulates division of stem cells from PC-3 human prostate cancer cell line

Cancer stem cells (CSCs) are a subpopulation that can drive recurrence and metastasis. Therefore, therapies targeting CSCs are required. Although previous findings have suggested that non-CSCs regulate the proliferation and differentiation of CSCs in the tumor microenvironment, the precise molecular mechanism is largely unknown. In this study, we found that a direct interaction between CSCs and non-CSCs downregulated CSC division in the PC-3 human prostate cancer cell line. We found that the proliferation of PC-3-derived CSCs (PrSCs) was significantly decreased (∼47%) in the presence of non-CSC-rich parental PC-3 cells compared with that in a culture in which they were absent. We observed no differences in PrSC proliferation when we indirectly cocultured them with PC-3 cells across a Transwell insert, and PrSCs that were transiently bound to immobilized PC-3 cells proliferated more slowly than those bound to PrSCs. The frequency of cell division with prior PrSC-PrSC contact was 2.8 times higher in the PrSC monoculture compared with that in the coculture with PC-3 cells. We found that the PrSCs were approximately 1.3 times more closely associated in the monoculture compared with the coculture with PC-3 cells, as determined by a cell proximity assay. The frequency of asymmetric PrSC division was 6.5% in the monoculture compared with 1.0% in the coculture with PC-3 cells (P < 0.045). By analyzing our data, we determined the importance of PrSC-non-CSC contact in regulating the frequency and mode of PrSC division. This regulation might be a valuable target for treating cancer.

Role of RHO family interacting cell polarization regulators (RIPORs) in health and disease: Recent advances and prospects

The RHO GTPase family has been suggested to play critical roles in cell growth, migration, and polarization. Regulators and effectors of RHO GTPases have been extensively explored in recent years. However, little attention has been given to RHO family interacting cell polarization regulators (RIPORs), a recently discovered protein family of RHO regulators. RIPOR proteins, namely, RIPOR1-3, bind directly to RHO proteins (A, B and C) via a RHO-binding motif and exert suppressive effects on RHO activity, thereby negatively influencing RHO-regulated cellular functions. In addition, RIPORs are phosphorylated by upstream protein kinases under chemokine stimulation, and this phosphorylation affects not only their subcellular localization but also their interaction with RHO proteins, altering the activation of RHO downstream targets and ultimately impacting cell polarity and migration. In this review, we provide an overview of recent studies on the function of RIPOR proteins in regulating RHO-dependent directional movement in immune responses and other pathophysiological functions.

Synergistic effect of anethole and doxorubicin alleviates cell proliferation, cell cycle arrest, and ER stress and promotes ROS-mediated apoptosis in triple-negative breast cancer cells

The heterogeneity and poor prognosis of triple-negative breast cancer (TNBC) have limited the treatment options and made clinical management challenging. This has nurtured a major effort to discover druggable molecular targets. Currently, chemotherapy is the primary treatment strategy for this disease. Doxorubicin is the most frequently used chemotherapeutic drug for TNBC and due to the fact that chemotherapeutic drugs have a lot of side effects, we evaluated the synergistic effect of the phytocompound anethole and doxorubicin. The cytotoxic effect of anethole in combination with doxorubicin on MDA-MB-231 cells was evaluated by various parameters, including apoptosis, cell cycle analysis, DNA damage, and cell proliferation. Furthermore, mitochondrial membranepotential (MMP), endoplasmic reticulum (ER) stress, and reactive oxygen species (ROS) levels were also evaluated in the cells treated with/without anethole and doxorubicin. Expression of the apoptotic proteins was evaluated by Western blot analysis. Initial evaluation of cytotoxicity of anethole on MDA-MB-231 cells demonstrated preferential suppression of cell proliferation and when treated along with doxorubicin it showed enhanced cytotoxicity with a synergistic effect. Cell cycle analysis revealed arrest at different stages of the cell cycle, such as sub G0-G1, G0-G1, S, and G2M in various treatment groups and apoptotic cell death was subsequently evident with propidium iodide (PI) staining. The synergistic action of anethole and doxorubicin effectively induced mitochondrial membrane potential loss, which, in turn, led to a burst of ROS production, which eventually produced unfolded protein response by damaging the ER. Synergistic anticancer effect was observed on exposure of MDA-MB-231 cells to anethole and doxorubicin in inducing cell death.

Membrane Localization of β-Catenin in Prostate Cancer PC3 Cells Treated with Teucrium persicum Boiss. Extract

Teucrium persicum Boiss. is an Iranian endemic plant which belongs to the Lamiaceae family and has been used to relieve pains in traditional Iranian medicine. We have previously found that treatment of prostate cancer PC3 cells with Teucrium persicum extract leads to the formation of small populations of epithelial cells. β-Catenin is a component of cell adherens junctions in epithelial cells and therefore, in this study, we have investigated the effect of Teucrium persicum extract on expression, cellular localization, and transcriptional activity of β-Catenin protein in PC-3 cells. Indirect immunofluorescence microscopy results showed that the cells treated with T. persicum extract had higher levels of β-Catenin protein at the cell membrane. Western blotting experiments produced consistent results. Gene expression studies by using a few β-Catenin-target genes including c-MYC, CYCLIN D1, and a reporter Luciferase gene under the control of several β-Catenin/TCF binding elements showed that treatment of PC3 cells with the methanolic extract of T. persicum decreases the transcriptional activities of β-Catenin. The results of this study provide further support for the anticancer properties of T. persicum. Definitely, more detailed molecular investigations are needed to find the mechanism(s) behind these effects. Highlightsβ-Catenin protein is a main component of Wnt signaling pathway and adherens junction.Activation of Wnt signaling pathway affects translocation of β-Catenin.Teucrium persicum extract induces β-Catenin localization at cell membrane.Teucrium persicum affects the transcriptional activity of β-Catenin.It stabilizes E-cadherin/β-Catenin protein complex and adherens junction.

Prostate cancer-derived holoclones: a novel and effective model for evaluating cancer stemness

Prostate cancer accounts for approximately 13.5% of all newly diagnosed male cancer cases. Significant clinical burdens remain in terms of ineffective prognostication, with overtreatment of insignificant disease. Additionally, the pathobiology underlying disease heterogeneity remains poorly understood. As the role of cancer stem cells in the perpetuation of aggressive carcinoma is being substantiated by experimental evidence, it is crucially important to understand the molecular mechanisms, which regulate key features of cancer stem cells. We investigated two methods for in vitro cultivation of putative prostate cancer stem cells based on ‘high-salt agar’ and ‘monoclonal cultivation’. Data demonstrated ‘monoclonal cultivation’ as the superior method. We demonstrated that ‘holoclones’ expressed canonical stem markers, retained the exclusive ability to generate poorly differentiated tumours in NOD/SCID mice and possessed a unique mRNA-miRNA gene signature. miRNA:Target interactions analysis visualised potentially critical regulatory networks, which are dysregulated in prostate cancer holoclones. The characterisation of this tumorigenic population lays the groundwork for this model to be used in the identification of proteomic or small non-coding RNA therapeutic targets for the eradication of this critical cellular population. This is significant, as it provides a potential route to limit development of aggressive disease and thus improve survival rates.

The Effect of Optically Induced Dielectrophoresis (ODEP)-Based Cell Manipulation in a Microfluidic System on the Properties of Biological Cells

Cell manipulation using optically induced dielectrophoresis (ODEP) in microfluidic systems has attracted the interest of scientists due to its simplicity. Although this technique has been successfully demonstrated for various applications, one fundamental issue has to be addressed—Whether, the ODEP field affects the native properties of cells. To address this issue, we explored the effect of ODEP electrical conditions on cellular properties. Within the experimental conditions tested, the ODEP-based cell manipulation with the largest velocity occurred at 10 Vpp and 1 MHz, for the two cancer cell types explored. Under this operating condition, however, the cell viability of cancer cells was significantly affected (e.g., 70.5 ± 10.0% and 50.6 ± 9.2% reduction for the PC-3 and SK-BR-3 cancer cells, respectively). Conversely, the exposure of cancer cells to the ODEP electrical conditions of 7–10 Vpp and 3–5 MHz did not significantly alter the cell viability, cell metabolic activity, and the EpCAM, VIM, and ABCC1 gene expression of cancer cells. Overall, this study fundamentally investigated the effect of ODEP electrical conditions on the cellular properties of cancer cells. The information obtained is crucially important for the utilization of ODEP-based cell manipulation in a microscale system for various applications.

The stem cell inhibitor salinomycin decreases colony formation potential and tumor-initiating population in docetaxel-sensitive and docetaxel-resistant prostate cancer cells

BACKGROUND

Prostate cancer (PCa) is one of the most frequently diagnosed tumors in men. In general, therapies for localized PCa are curative. However, treatment of advanced PCa is considered palliative since development of therapy resistance occurs rapidly. It has been shown that tumor-initiating cells are likely involved in therapy resistance. They are not eliminated by conventional therapies and thereby lead to tumor progression and relapse. The aim of this study was to evaluate the effects of the known stem cell inhibitor salinomycin on this critical subpopulation of cells.

METHODS

Expression of the cell surface markers CD24 and CD44 was assessed by immunofluorescence and fluorescence-activated cell sorting. Colony formation efficiency and classification of colony types with varying tumor-initiating potential (holoclones, meroclones, and paraclones) were analyzed in an automated way by the newly developed CATCH-colonies software in the absence or presence of salinomycin.

RESULTS

Automated high-resolution colony formation analysis consistently identified the various colony types in a broad range of PCa cell lines. Serial clonogenic assays confirmed that holoclones show the highest colony formation potential and maintain their tumor-initiating capacity over multiple rounds. Furthermore, holoclones showed high expression of CD44, while CD24 was not expressed in these clones, thus representing the well-described tumor-initiating CD24^- /CD44^high population. Salinomycin decreased the CD24^- /CD44^high population in both docetaxel-sensitive PC3 and docetaxel-resistant (DR) PC3-DR. Moreover, treatment of PC3, DU145, PC3-DR, and DU145-DR with salinomycin led to a significant reduction in the colony formation potential by targeting the colonies with high tumor-initiating potential.

CONCLUSIONS

Taken together, we demonstrated that salinomycin specifically targets the tumor-initiating cell population in docetaxel-sensitive and docetaxel-resistant PCa cells and may represent a potential therapeutic approach for the treatment of advanced PCa.

Cellular effect of styrene substituted biscoumarin caused cellular apoptosis and cell cycle arrest in human breast cancer cells

BACKGROUND

Coumarins occurs naturally across plant kingdoms exhibits significant pharmacological properties and pharmacokinetic activity. The conventional, therapeutic agents are often associated with poor stability, absorption and increased side effects. Therefore, identification of a drug that has little or no-side effect on humans is consequential. Here, we investigated the antiproliferative activity of styrene substituted biscoumarin against various human breast cancer cell lines, such as MCF-7, (ER-) MDA-MB-231 and (AR+) MDA-MB-453. Styrene substituted biscoumarin induced cell death by apoptosis in MDA-MB-231 cell line was analyzed.

METHODS

Antiproliferative activity of Styrene substituted biscoumarin was performed by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Styrene substituted biscoumarin induced apoptosis was assessed by Hoechst staining, Annexin V-fluorescein isothiocyanate/propidium iodide (Annexin V-FITC/PI) staining and flow cytometric analysis. Migratory and proliferating characteristic of breast cancer cell line MDA-MB-231 was also analyzed by wound healing and colony formation assay. Furthermore, mRNA expression of BAX and BCL-2 were quantified using qRT-PCR and protein expression level analyzed by Western blot.

RESULTS

The inhibition concentration (IC₅₀) of styrene substituted biscoumarin was assayed against three breast cancer cell lines. The inhibition concentration (IC₅₀) value of styrene substituted biscoumarin toward MDA-MB-231, MDA-MB-453 and MCF-7 cell lines was 5.63, 7.30 and 10.84μg/ml respectively. Styrene substituted biscoumarin induced apoptosis was detected by Hoechst staining, DAPI/PI analysis and flow-cytometric analysis. The migration and proliferative efficiency of MDA-MB-231 cells were completely arrested upon styrene substituted biscoumarin treatment. Also, mRNA gene expression and protein expression of pro-apoptotic (BAX) and anti-apoptotic (BCL-2) genes were analyzed by qRT-PCR and western blot analysis upon styrene substituted biscoumarin treatment to MDA-MB-231 cells. Our results showed that styrene substituted biscoumarin downregulated BCL-2 gene expression and upregulated BAX gene expression to trigger apoptotic process.

CONCLUSION

Styrene substituted biscoumarin could induce apoptosis through intrinsic mitochondrial pathway in breast cancer cell lines, particularly in MDA-MB-231. Our data suggest that styrene substituted biscoumarin may act as a potential chemotherapeutic agent against breast cancer.

Glycolytic reprogramming through PCK2 regulates tumor initiation of prostate cancer cells

Tumor-initiating cells (TICs) play important roles in tumor progression and metastasis. Identifying the factors regulating TICs may open new avenues in cancer therapy. Here, we show that TIC-enriched prostate cancer cell clones use more glucose and secrete more lactate than TIC-low clones. We determined that elevated levels of phosphoenolpyruvate carboxykinase isoform 2 (PCK2) are critical for the metabolic switch and the maintenance of TICs in prostate cancer. Information from prostate cancer patient databases revealed that higher PCK2 levels correlated with more aggressive tumors and lower survival rates. PCK2 knockdown resulted in low TIC numbers, increased cytosolic acetyl-CoA and cellular protein acetylation. Our data suggest PCK2 promotes tumor initiation by lowering acetyl-CoA level through reducing the mitochondrial tricarboxylic acid (TCA) cycle. Thus, PCK2 is a potential therapeutic target for aggressive prostate tumors.

ΔNp63α promotes adhesion of metastatic prostate cancer cells to the bone through regulation of CD82

ΔNp63α is a critical mediator of epithelial development and stem cell function in a variety of tissues including the skin and breast, while overexpression of ΔNp63α acts as an oncogene to drive tumor formation and cancer stem cell properties in squamous cell carcinoma. However, with regards to the prostate, while ΔNp63α is expressed in the basal stem cells of the mature gland, during adenocarcinoma development, its expression is lost and its absence is used to clinically diagnose the malignant state. Surprisingly, here we identify a sub-population of bone metastatic prostate cancer cells in the PC3 cell line that express ΔNp63α. Interestingly, we discovered that ΔNp63α favors adhesion and stem-like growth of these cells in the bone microenvironment. In addition, we show that these properties require expression of the target gene CD82. Together, this work uncovers a population of bone metastatic prostate cancer cells that express ΔNp63α, and provides important information about the mechanisms of bone metastatic colonization. Finally, we identify metastasis-promoting properties for the tetraspanin family member CD82.

Nanomedicine strategies for sustained, controlled and targeted treatment of cancer stem cells

Cancer stem cells (CSCs) are original cancer cells that are of characteristics associated with normal stem cells. CSCs are toughest against various treatments and thus responsible for cancer metastasis and recurrence. Therefore, development of specific and effective treatment of CSCs plays a key role in improving survival and life quality of cancer patients, especially those in the metastatic stage. Nanomedicine strategies, which include prodrugs, micelles, liposomes and nanoparticles of biodegradable polymers, could substantially improve the therapeutic index of conventional therapeutics due to its manner of sustained, controlled and targeted delivery of high transportation efficiency across the cell membrane and low elimination by intracellular autophagy, and thus provide a practical solution to solve the problem encountered in CSCs treatment. This review gives briefly the latest information to summarize the concept, strategies, mechanisms and current status as well as future promises of nanomedicine strategies for treatment of CSCs.

STAT3 pathway regulates lung-derived brain metastasis initiating cell capacity through miR-21 activation

Brain metastases (BM) represent the most common tumor to affect the adult central nervous system. Despite the increasing incidence of BM, likely due to consistently improving treatment of primary cancers, BM remain severely understudied. In this study, we utilized patient-derived stem cell lines from lung-to-brain metastases to examine the regulatory role of STAT3 in brain metastasis initiating cells (BMICs). Annotation of our previously described BMIC regulatory genes with protein-protein interaction network mapping identified STAT3 as a novel protein interactor. STAT3 knockdown showed a reduction in BMIC self-renewal and migration, and decreased tumor size in vivo. Screening of BMIC lines with a library of STAT3 inhibitors identified one inhibitor to significantly reduce tumor formation. Meta-analysis identified the oncomir microRNA-21 (miR-21) as a target of STAT3 activity. Inhibition of miR-21 displayed similar reductions in BMIC self-renewal and migration as STAT3 knockdown. Knockdown of STAT3 also reduced expression of known downstream targets of miR-21. Our studies have thus identified STAT3 and miR-21 as cooperative regulators of stemness, migration and tumor initiation in lung-derived BM. Therefore, STAT3 represents a potential therapeutic target in the treatment of lung-to-brain metastases.

Investigation of the molecular mechanisms underlying metastasis in prostate cancer by gene expression profiling

The present study aimed to screen potential genes associated with metastatic prostate cancer (PCa), in order to improve the understanding of the mechanisms underlying PCa metastasis. The GSE3325 microarray dataset, which was downloaded from the Gene Expression Omnibus database, consists of seven clinically localized PCa samples, six hormone-refractory metastatic PCa samples and six benign prostate tissue samples. The Linear Models for Microarray Data package was used to identify differentially-expressed genes (DEGs) and a hierarchical cluster analysis for DEGs was performed with the pheatmap package. Furthermore, potential functions for the DEGs were predicted by a functional enrichment analysis. Subsequently, microRNAs (miRNAs) potentially involved in the regulation of PCa metastasis were identified by WebGestalt software, and the miRNA-DEG regulatory network was visualized using Cytoscape. In addition, a pathway enrichment analysis for DEGs in the regulatory network was performed. A total of 306 and 2,073 genes were differentially expressed in the clinically localized PCa and the metastatic PCa groups, respectively, as compared with the benign prostate group, of which 174 were differentially expressed in both groups. A number of the DEGs, including CAMK2D and SH3BP4, were significantly enriched in the cell cycle, and others, such as MAF, were associated with the regulation of cell proliferation. Furthermore, some DEGs (CAMK2D and PCDH17) were observed to be regulated by miR-30, whereas others (ADCY2, MAF, SH3BP4 and PCDH17) were modulated by miR-182. Additionally, ADCY2 and CAMK2D were distinctly enriched in the calcium signaling pathway. The present study identified novel DEGs, including ADCY2, CAMK2D, MAF, SH3BP4 and PCDH17, that may be involved in the metastasis of PCa.

Phosphodiesterase 5/protein kinase G signal governs stemness of prostate cancer stem cells through Hippo pathway

Cancer stem cells (CSC) are critical for initiation, metastasis, and relapse of cancers, however, the underlying mechanism governing stemness of CSC remains unknown. Herein, we have investigated the roles of phosphodiesterase 5 (PDE5) in stemness of prostate cancer cells. Both PDE5 and WW domain-containing transcription regulator protein-1 (TAZ), a core effector of Hippo pathway, are highly expressed in the PC3-derived cancer stem cells (PCSC). Either TAZ knockdown or inhibition of PDE5 activity attenuated colony formation, altered expression patterns of stem cell markers, and enhanced cisplatin cytotoxicity, resulting in attenuation of stemness in PCSC. In addition, inhibition of PDE5 activity by its specific inhibitors activates cGMP-dependent protein kinase G (PKG), which in turn induces MST/LATS kinases, resulting in cytosolic degradation of TAZ and activation of Hippo pathway. Accordingly, knockdown of TAZ almost completely abolished PDE5 inhibitor-induced attenuation in stemness in cultured PCSC, whereas knockdown of TAZ not only abolished PDE5 inhibitor-induced attenuation in stemness but also facilitated PDE5 inhibitor-induced trans-differentiation in PCSC xenografts. Together, the present study has uncovered that PDE/cGMP/PKG signal targets to Hippo/TAZ pathway in maintaining stemness of PCSC, and suggested that PDE5 inhibitors in combination with chemotherapeutic agents could effectively prevent initiation, metastasis, and relapse of prostate cancer.

4-Hydroxybenzoic acid derivatives as HDAC6-specific inhibitors modulating microtubular structure and HSP90α chaperone activity against prostate cancer

Histone deacetylase (HDAC)6 is a unique isoenzyme targeting specific substrates including α-tubulin and heat shock protein (HSP)90. HDAC6 is involved in protein trafficking and degradation, cell shape and migration. Deregulation of HDAC6 activity is associated with a variety of diseases including cancer leading to a growing interest for developing HDAC6 inhibitors. Here, we identified two new structurally related 4-hydroxybenzoic acids as selective HDAC6 inhibitors reducing proliferation, colony and spheroid formation as well as viability of prostate cancer cells. Both compounds strongly enhanced α-tubulin acetylation leading to remodeling of microtubular organization. Furthermore, 4-hydroxybenzoic acids decreased HSP90α regulation of the human androgen receptor in prostate cancer cells by increasing HSP90α acetylation levels. Collectively, our data support the potential of 4-hydroxybenzoic acid derivatives as HDAC6-specific inhibitors with anti-cancer properties.

LEF1 Targeting EMT in Prostate Cancer Invasion Is Regulated by miR-34a

The microRNA-34a (miR-34a), a tumor-suppressive microRNA (miRNA), is implicated in epithelial-mesenchymal transition (EMT) and cancer stem cells. Lymphoid enhancer-binding factor-1 (LEF1) is a key transcription factor in the Wnt signaling pathway, and has been suggested to be involved in regulation of cell proliferation and invasion. Here, the molecular mechanism of miR-34a and LEF1 in cooperatively regulating prostate cancer cell invasion is described. Molecular profiling analysis of miRNA levels in prostate cancer cells revealed a negative correlation between miR-34a and LEF1 expression, and the downregulation of LEF1 by miR-34a was confirmed by luciferase assays. Furthermore, miR-34a specifically repressed LEF1 expression through direct binding to its 3'-untranslated regions (3'-UTR). miR-34a modulated the levels of LEF1 to regulate EMT in prostate cancer cells. Functionally, miR-34a negatively correlated with the migration and invasion of prostate cancer cells through LEF1. An analysis of miR-34a expression levels in matched human tumor and benign tissues demonstrated consistent and statistically significant downregulation of miR-34a in primary prostate cancer specimens. These data strongly suggest that miR-34a/LEF1 regulation of EMT plays an important role in prostate cancer migration and invasion.

IMPLICATIONS

The miR-34a-LEF1 axis represents a potential molecular target for novel therapeutic strategies in prostate cancer.

BAZ2A (TIP5) is involved in epigenetic alterations in prostate cancer and its overexpression predicts disease recurrence

Prostate cancer is driven by a combination of genetic and/or epigenetic alterations. Epigenetic alterations are frequently observed in all human cancers, yet how aberrant epigenetic signatures are established is poorly understood. Here we show that the gene encoding BAZ2A (TIP5), a factor previously implicated in epigenetic rRNA gene silencing, is overexpressed in prostate cancer and is paradoxically involved in maintaining prostate cancer cell growth, a feature specific to cancer cells. BAZ2A regulates numerous protein-coding genes and directly interacts with EZH2 to maintain epigenetic silencing at genes repressed in metastasis. BAZ2A overexpression is tightly associated with a molecular subtype displaying a CpG island methylator phenotype (CIMP). Finally, high BAZ2A levels serve as an independent predictor of biochemical recurrence in a cohort of 7,682 individuals with prostate cancer. This work identifies a new aberrant role for the epigenetic regulator BAZ2A, which can also serve as a useful marker for metastatic potential in prostate cancer.

Traceable clonal culture and chemodrug assay of heterogeneous prostate carcinoma PC3 cells in microfluidic single cell array chips

Cancer heterogeneity has received considerable attention for its role in tumor initiation and progression, and its implication for diagnostics and therapeutics in the clinic. To facilitate a cellular heterogeneity study in a low cost and highly efficient manner, we present a microfluidic platform that allows traceable clonal culture and characterization. The platform captures single cells into a microwell array and cultures them for clonal expansion, subsequently allowing on-chip characterization of clonal phenotype and response against drug treatments. Using a heterogeneous prostate cancer model, the PC3 cell line, we verified our prototype, identifying three different sub-phenotypes and correlating their clonal drug responsiveness to cell phenotype.

H460 non-small cell lung cancer stem-like holoclones yield tumors with increased vascularity

Cancer stem-like cells were isolated from several human tumor cell lines by limiting dilution assays and holoclone morphology, followed by assessment of self-renewal capacity, tumor growth, vascularity, and blood perfusion. H460 holoclone-derived tumors grew slower than parental H460 tumors, but displayed significantly increased microvessel density and tumor blood perfusion. Microarray analysis identified 177 differentially regulated genes in the holoclone-derived tumors, of which 47 were associated with angiogenesis. The dysregulated genes include several small leucine-rich proteoglycans that may modulate angiogenesis and serve as novel therapeutic targets for inhibiting cancer stem cell-driven angiogenesis.

Dark side of the exosome: the role of the exosome in cancer metastasis and targeting the exosome as a strategy for cancer therapy

ABSTRACT: 

Cell–cell communication is essential for the regulation of various biological phenomena in multicellular organisms, including development and homeostasis. Deregulation of these interactions leads to inappropriate cell–cell communication, resulting in disease development. Cancer cells communicate closely with the cells in their microenvironment, and this communication promotes malignancy via abnormal growth, invasion, drug resistance and metastasis. Understanding cell–cell interactions in cancer is essential for the development of novel anticancer agents. As a result, discovering the communication tools used by cancer cells is important to understanding these interactions. In this review, we summarize the recent findings regarding exosome-mediated cancer development. In addition, we propose that targeting the exosome represents a novel strategy for cancer therapy.

Clonogenicity: holoclones and meroclones contain stem cells

When primary cultures of normal cells are cloned, three types of colony grow, called holoclones, meroclones and paraclones. These colonies are believed to be derived from stem cells, transit-amplifying cells and differentiated cells respectively. More recently, this approach has been extended to cancer cell lines. However, we observed that meroclones from the prostate cancer cell line DU145 produce holoclones, a paradoxical observation as meroclones are thought to be derived from transit-amplifying cells. The purpose of this study was to confirm this observation and determine if both holoclones and meroclones from cancer cell lines contain stem cells. We demonstrated that both holoclones and meroclones can be serially passaged indefinitely, are highly proliferative, can self-renew to form spheres, are serially tumorigenic and express stem cell markers. This study demonstrates that the major difference between holoclones and meroclones derived from a cancer cell line is the proportion of stem cells within each colony, not the presence or absence of stem cells. These findings may reflect the properties of cancer as opposed to normal cells, perhaps indicating that the hierarchy of stem cells is more extensive in cancer.

Functional links between Snail-1 and Cx43 account for the recruitment of Cx43-positive cells into the invasive front of prostate cancer

Suppressive function of connexin(Cx)43 in carcinogenesis was recently contested by reports that showed a multifaceted function of Cx43 in cancer progression. These studies did not attempt to model the dynamics of intratumoral heterogeneity involved in the metastatic cascade. An unorthodox look at the phenotypic heterogeneity of prostate cancer cells in vitro enabled us to identify links between Cx43 functions and Snail-1-regulated functional speciation of invasive cells. Incomplete Snail-1-dependent phenotypic shifts accounted for the formation of phenotypically stable subclones of AT-2 cells. These subclones showed diverse predilection for invasive behavior. High Snail-1 and Cx43 levels accompanied high motility and nanomechanical elasticity of the fibroblastoid AT-2_Fi2 subclone, which determined its considerable invasiveness. Transforming growth factor-β and ectopic Snail-1 overexpression induced invasiveness and Cx43 expression in epithelioid AT-2 subclones and DU-145 cells. Functional links between Snail-1 function and Cx43 expression were confirmed by Cx43 downregulation and phenotypic shifts in AT-2_Fi2, DU-145 and MAT-LyLu cells upon Snail-1 silencing. Corresponding morphological changes and Snail-1 downregulation were seen upon Cx43 silencing in AT-2_Fi2 cells. This indicates that feedback loops between both proteins regulate cell invasive behavior. We demonstrate that Cx43 may differentially predispose prostate cancer cells for invasion in a coupling-dependent and coupling-independent manner. When extrapolated to in vivo conditions, these data show the complexity of Cx43 functions during the metastatic cascade of prostate cancer. They may explain how Cx43 confers a selective advantage during cooperative invasion of clonally evolving, invasive prostate cancer cell subpopulations.

The relationship of cancer stem cells in urological cancers

Numerous studies are ongoing to identify and isolate cancer stem cells from cancers of genito-urinary tracts. Better understanding of their role in prostate, urothelial and kidney cancer origin, growth and progression opens new pathways in development of more effective treatment methods. However there are still many issues before advances in this field can be introduced for clinical application. This review addresses current achievements in cancer stem cells research in uro-oncology.

Impact of tumor vascularity on responsiveness to antiangiogenesis in a prostate cancer stem cell-derived tumor model

Drugs that target the tumor vasculature and inhibit angiogenesis are widely used for cancer treatment. Individual tumors show large differences in vascularity, but it is uncertain how these differences affect responsiveness to antiangiogenesis. We investigated this question using two closely related prostate cancer models that differ markedly in tumor vascularity: PC3, which has very low vascularity, and the PC3-derived cancer stem-like cell holoclone PC3/2G7, which forms tumors with high microvessel density, high tumor blood flow, and low hypoxia compared with parental PC3 tumors. Three angiogenesis inhibitors (axitinib, sorafenib, and DC101) all induced significantly greater decreases in tumor blood flow and microvessel density in PC3/2G7 tumors compared with PC3 tumors, as well as significantly greater decreases in tumor cell proliferation and cell viability and a greater increase in apoptosis. The increased sensitivity of PC3/2G7 tumors to antiangiogenesis indicates they are less tolerant of low vascularity and suggests they become addicted to their oxygen- and nutrient-rich environment. PC3/2G7 tumors showed strong upregulation of the proangiogenic factors chemokine ligand 2 (CCL2) and VEGFA compared with PC3 tumors, which may contribute to their increased vascularity, and they have significantly lower endothelial cell pericyte coverage, which may contribute to their greater sensitivity to antiangiogenesis. Interestingly, high levels of VEGF receptor-2 were expressed on PC3 but not PC3/2G7 tumor cells, which may contribute to the growth static response of PC3 tumors to VEGF-targeted antiangiogenesis. Finally, prolonged antiangiogenic treatment led to resumption of PC3/2G7 tumor growth and neovascularization, indicating these cancer stem-like cell-derived tumors can adapt and escape from antiangiogenesis.

Isolation and enrichment of PC-3 prostate cancer stem-like cells using MACS and serum-free medium

Prostate cancer stem-like cells (PCSLCs) are considered to be the ‘seed’ of prostate cancer. The aim of this study was to confirm that the PC-3 cells, which we isolated and enriched from PC-3 cells through magnetic bead cell sorting (MACS) and serum-free medium (SFM) culture, were PCSLCs. Combinations of MACS, flow cytometry (FCM), SFM and immunocytochemistry (ICC) were used to ensure the positive expression of CD133 and CD44 on PC-3 and sphere-forming cell membranes. Self-renewal, multi-potential differentiation, unlimited proliferation and permanency assays were also applied to indentify whether the PC-3 cells exhibited the characteristics of cancer stem cells (CSCs). As a result, there was a low proportion of PCSLCs in the PC-3 cells. In the FCM assay, the proportion of cells expressing CD133 or CD44 in the PC-3 cells was 0.51 and 0.31%, respectively. In addition, we found that the proportion of PC-3 cells sorted by MACS that expressed CD133 was significantly increased compared with that of the sphere-forming cells cultured in SFM (99.09 vs. 84.80%, P<0.05), while no difference was observed in the proportion of cells expressing CD44 between them (99.88 vs. 99.82%, P>0.05). The expression of PAP and AR as detected by western blot analysis of induced PCSLCs was significantly increased compared with that of uninduced PCSLCs (P<0.05); the proliferation capacity of PCSLCs was significantly higher than that of both the PC-3 cells (P<0.05) and induced PCSLCs (P<0.05). Furthermore, the PCSLCs that were isolated from SFM and MACS both demonstrated certain characteristics of stem cells and should be considered as stem cell-like. These data may hold potential for further exploring the role of PCSLCs.

Prolonged androgen deprivation leads to downregulation of androgen receptor and prostate-specific membrane antigen in prostate cancer cells

Emergence of androgen-independent cancer cells during androgen deprivation therapy presents a significant challenge to successful treatment outcomes in prostate cancer. Elucidating the role of androgen deprivation in the transition from an androgen-dependent to an androgen-independent state may enable the development of more effective therapeutic strategies against prostate cancer. Herein, we describe an in vitro model for assessing the effects of continuous androgen-deprivation on prostate cancer cells (LNCaP) with respect to the expression of two prostate-specific markers: the androgen receptor (AR) and prostate-specific membrane antigen (PSMA). Compared with androgen-containing normal growth medium, androgen-deprived medium apparently induced the concomitant downregulation of AR and PSMA over time. Decreased protein levels were confirmed by fluorescence imaging, western blotting and enzymatic activity studies. In contrast to the current understanding of AR and PSMA in prostate cancer progression, our data demonstrated that androgen-deprivation induced a decrease in AR and PSMA levels in androgen-sensitive LNCaP cells, which may be associated with the development of more aggressive disease-state following androgen deprivation therapy.

Cancer stem cell targeting: the next generation of cancer therapy and molecular imaging

Cancer stem cells (CSCs) have the capacity to generate the heterogeneous lineages of all cancer cells comprising a tumor and these populations of cells are likely to be more relevant in determining prognosis. However, these cells do not operate in isolation, but instead rely upon signals co-opted from their microenvironment, making the targeting and imaging of CSCs within a cancer mass a daunting task. A better understanding of the molecular cell biology underlying CSC pathology will facilitate the development of new therapeutic targets and novel strategies for the successful eradication of cancer. In addition, the continued investigation of sensitive molecular-imaging modalities will enable more accurate staging, treatment planning and the ability to monitor the effectiveness of CSC-targeted therapies in vivo. In this review, we explore the possibilities and limitations of CSC-directed therapies and molecular imaging modalities.

CD133(+)EpCAM(+) phenotype possesses more characteristics of tumor initiating cells in hepatocellular carcinoma Huh7 cells

Background: EpCAM or CD133 has been used as the tumor initiating cells (TICs) marker in hepatocellular carcinoma (HCC). We investigated whether cells expressing with both EpCAM and CD133 surface marker were more representative for TICs in hepatocellular carcinoma Huh7 cells.

Methods: Four different phenotypes of CD133⁺EpCAM⁺, CD133⁺EpCAM^-, CD133^-EpCAM⁺ and CD133^-EpCAM^- in Huh7 cells were sorted by flow cytometry. Then cell differentiation, self-renewal, drug-resistance, spheroid formation and the levels of stem cell-related genes were detected to compare the characteristics of TICs. The ability of tumorigenicity was measured in nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice to verify TICs.

Results: CD133⁺EpCAM⁺ cells have many characteristics of TICs in Huh7 cells compared with CD133⁺EpCAM^-, CD133^-EpCAM⁺, CD133^-EpCAM^- cells, including enrichment in side population cells, higher differentiation capacity, increased colony-formation ability, preferential expression of stem cell-related genes, appearance of drug-resistant to some chemotherapeutics, more spheroid formation of culture cells and stronger tumorigenicity in NOD/SCID mice.

Conclusion: CD133⁺EpCAM⁺ phenotype is precisely represented TICs in Huh7 cells. It might be useful for studying biology mechanism of TICs in hepatocellular carcinoma and screening new targets for cancer therapy.

CD133(+)EpCAM(+) phenotype possesses more characteristics of tumor initiating cells in hepatocellular carcinoma Huh7 cells

BACKGROUND

EpCAM or CD133 has been used as the tumor initiating cells (TICs) marker in hepatocellular carcinoma (HCC). We investigated whether cells expressing with both EpCAM and CD133 surface marker were more representative for TICs in hepatocellular carcinoma Huh7 cells.

METHODS

Four different phenotypes of CD133(+)EpCAM(+), CD133(+)EpCAM(-), CD133(-)EpCAM(+) and CD133(-)EpCAM(-) in Huh7 cells were sorted by flow cytometry. Then cell differentiation, self-renewal, drug-resistance, spheroid formation and the levels of stem cell-related genes were detected to compare the characteristics of TICs. The ability of tumorigenicity was measured in nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice to verify TICs.

RESULTS

CD133(+)EpCAM(+) cells have many characteristics of TICs in Huh7 cells compared with CD133(+)EpCAM(-), CD133(-)EpCAM(+), CD133(-)EpCAM(-) cells, including enrichment in side population cells, higher differentiation capacity, increased colony-formation ability, preferential expression of stem cell-related genes, appearance of drug-resistant to some chemotherapeutics, more spheroid formation of culture cells and stronger tumorigenicity in NOD/SCID mice.

CONCLUSION

CD133(+)EpCAM(+) phenotype is precisely represented TICs in Huh7 cells. It might be useful for studying biology mechanism of TICs in hepatocellular carcinoma and screening new targets for cancer therapy.

Synergistic effect of SCF and G-CSF on stem-like properties in prostate cancer cell lines

Bone marrow metastases are formed in the late phases of prostate cancer disease. Stem cell factor (SCF) and granulocyte colony-stimulating factor (G-CSF) are present in the microenvironment of the bone marrow and play a vital role in cell biology therein. The present study was to investigate the influence of SCF and G-CSF on stem-like properties in prostate cancer cell lines. Upon stimulation with SCF or G-CSF, higher levels of CD117, ABCG2, and CD44 were observed in PC-3 and DU145 cells examined by flow cytometry. Simultaneously, the expressions of Oct3/4 and Nanog were upregulated. Moreover, quantitative real-time PCR verified that the increased Nanog under the stimulations was mostly derived from NANOGP8. In parallel with the increasing expressions of these proteins, higher colony and sphere formation efficiencies were seen in these cells in response to the cytokine stimulations. Furthermore, a synergistic effect of SCF and G-CSF on colony and sphere formations and ABCG2 expression was disclosed. Our results indicate a favorable bone marrow niche for prostate cancer cells where higher levels of cell stemness are maintained at least partly by the cytokines SCF and G-CSF.

Galiellalactone inhibits stem cell-like ALDH-positive prostate cancer cells

Galiellalactone is a potent and specific inhibitor of STAT3 signaling which has been shown to possess growth inhibitory effects on prostate cancer cells expressing active STAT3. In this study we aimed to investigate the effect of galiellalactone on prostate cancer stem cell-like cells. We explored the expression of aldehyde dehydrogenase (ALDH) as a marker for cancer stem cell-like cells in different human prostate cancer cell lines and the effects of galiellalactone on ALDH expressing (ALDH+) prostate cancer cells. ALDH+ subpopulations were detected and isolated from the human prostate cancer cell lines DU145 and long-term IL-6 stimulated LNCaP cells using ALDEFLUOR® assay and flow cytometry. In contrast to ALDH− cells, ALDH+ prostate cancer cells showed cancer stem cell-like characteristics such as increased self-renewing and colony forming capacity and tumorigenicity. In addition, ALDH+ cells showed an increased expression of putative prostate cancer stem cell markers (CD44 and integrin α2β1). Furthermore, ALDH+ cells expressed phosphorylated STAT3. Galiellalactone treatment decreased the proportion of ALDH+ prostate cancer cells and induced apoptosis of ALDH+ cells. The gene expression of ALDH1A1 was downregulated in vivo in galiellalactone treated DU145 xenografts. These findings emphasize that targeting the STAT3 pathway in prostate cancer cells, including prostate cancer stem cell-like cells, is a promising therapeutic approach and that galiellalactone is an interesting compound for the development of future prostate cancer drugs.