Glycogen synthase kinase-3β inhibition depletes the population of prostate cancer stem/progenitor-like cells and attenuates metastatic growth

PQR309, a dual PI3K/mTOR inhibitor, synergizes with gemcitabine by impairing the GSK-3β and STAT3/HSP60 signaling pathways to treat nasopharyngeal carcinoma

End-stage nasopharyngeal carcinoma (NPC) has unsatisfactory survival. The limited benefit of chemotherapy and the scarcity of targeted drugs are major challenges in NPC. New approaches to treat late-stage NPC are urgently required. In this study, we explored whether the dual PI3K/mTOR inhibitor, PQR309, exerted a favorable antineoplastic effect and sensitized the response to gemcitabine in NPC. We observed that PI3K expression was positive and elevated in 14 NPC cell lines compared with that in normal nasopharygeal cell lines. Patients with NPC with higher PI3K levels displayed poorer prognosis. We subsequently showed that PQR309 alone effectively decreased the viability, invasiveness, and migratory capability of NPC cells and neoplasm development in mice xenograft models, and dose-dependently induced apoptosis. More importantly, PQR309 remarkably strengthened the anti-NPC function of gemcitabine both in vivo and in vitro. Mechanistically, PQR309 sensitized NPC to gemcitabine by increasing caspase pathway-dependent apoptosis, blocking GSK-3β and STAT3/HSP60 signaling, and ablating epithelial-mesenchyme transition. Thus, targeting PI3K/mTOR using PQR309 might represent a treatment option to promote the response to gemcitabine in NPC, and provides a theoretical foundation for the study of targeted drugs combined with chemotherapy for NPC.

Suspension state affects the stemness of breast cancer cells by regulating the glycogen synthase kinase-3β

Circulating tumor cells (CTCs) are considered an important factor involved in tumor metastasis and can overcome mechanical interactions to gain the ability to distant metastasis. The previous study had shown that the suspension state could regulate the stemness of breast cancer cells (BCCs). However, the specific molecular mechanisms involved have not yet been explored clearly. In this study, MCF-7 and MDA-MBA-231 BCCs were cultured in suspension and adherent. The effect of suspension state on BCCs was further elucidated by observing suspension cell clusters, sorting CD44+/CD24- cell subpopulation and detecting self-renewal ability. Furthermore, it was found that glycogen synthase kinase-3β (GSK-3β) was significantly down-regulated in MCF-7 suspension cells along with the activation of the Wnt/β-catenin signaling, but the converse was true for MDA-MB-231 cells. Subsequently, GSK-3β was differentially expressed in MCF-7 suspension cells. The activation of the Wnt/β-catenin signaling, epithelial-mesenchymal transition (EMT) and stemness were all inhibited when GSK-3 was overexpressed in suspension MCF-7 cells. While GSK-3β was down-regulated, it further promoted the Wnt/β-catenin signaling, mesenchymal characteristic and stemness of MCF-7 cells. This study demonstrated that suspension state could activate the Wnt/β-catenin signaling by inhibiting GSK-3β to promote the stemness of epithelial BCCs, providing a therapeutic strategy for targeted CTCs.

Understanding and targeting prostate cancer cell heterogeneity and plasticity

Prostate cancer (PCa) is a prevalent malignancy that occurs primarily in old males. Prostate tumors in different patients manifest significant inter-patient heterogeneity with respect to histo-morphological presentations and molecular architecture. An individual patient tumor also harbors genetically distinct clones in which PCa cells display intra-tumor heterogeneity in molecular features and phenotypic marker expression. This inherent PCa cell heterogeneity, e.g., in the expression of androgen receptor (AR), constitutes a barrier to the long-term therapeutic efficacy of AR-targeting therapies. Furthermore, tumor progression as well as therapeutic treatments induce PCa cell plasticity such that AR-positive PCa cells may turn into AR-negative cells and prostate tumors may switch lineage identity from adenocarcinomas to neuroendocrine-like tumors. This induced PCa cell plasticity similarly confers resistance to AR-targeting and other therapies. In this review, I first discuss PCa from the perspective of an abnormal organ development and deregulated cellular differentiation, and discuss the luminal progenitor cells as the likely cells of origin for PCa. I then focus on intrinsic PCa cell heterogeneity in treatment-naïve tumors with the presence of prostate cancer stem cells (PCSCs). I further elaborate on PCa cell plasticity induced by genetic alterations and therapeutic interventions, and present potential strategies to therapeutically tackle PCa cell heterogeneity and plasticity. My discussions will make it clear that, to achieve enduring clinical efficacy, both intrinsic PCa cell heterogeneity and induced PCa cell plasticity need to be targeted with novel combinatorial approaches.

GSK3β as a novel promising target to overcome chemoresistance in pancreatic cancer

Pancreatic cancer is an aggressive malignancy with increasing incidence and poor prognosis due to its late diagnosis and intrinsic chemoresistance. Most pancreatic cancer patients present with locally advanced or metastatic disease characterized by inherent resistance to chemotherapy. These features pose a series of therapeutic challenges and new targets are urgently needed. Glycogen synthase kinase 3 beta (GSK3β) is a conserved serine/threonine kinase, which regulates key cellular processes including cell proliferation, DNA repair, cell cycle progression, signaling and metabolic pathways. GSK3β is implicated in non-malignant and malignant diseases including inflammation, neurodegenerative diseases, diabetes and cancer. GSK3β recently emerged among the key factors involved in the onset and progression of pancreatic cancer, as well as in the acquisition of chemoresistance. Intensive research has been conducted on key oncogenic functions of GSK3β and its potential as a druggable target; currently developed GSK3β inhibitors display promising results in preclinical models of distinct tumor types, including pancreatic cancer. Here, we review the latest findings about GSK-3β biology and its role in the development and progression of pancreatic cancer. Moreover, we discuss therapeutic agents targeting GSK3β that could be administered as monotherapy or in combination with other drugs to surmount chemoresistance. Several studies are also defining potential gene signatures to identify patients who might benefit from GSK3β-based therapeutic intervention. This detailed overview emphasizes the urgent need of additional molecular studies on the impact of GSK3β inhibition as well as structural analysis of novel compounds and omics studies of predictive biomarkers.

HGK promotes metastatic dissemination in prostate cancer

Metastasis is the process of cancer cell dissemination from primary tumors to different organs being the bone the preferred site for metastatic homing of prostate cancer (PCa) cells. Prostate tumorigenesis is a multi-stage process that ultimately tends to advance to become metastatic PCa. Once PCa patients develop skeletal metastases, they eventually succumb to the disease. Therefore, it is imperative to identify essential molecular drivers of this process to develop new therapeutic alternatives for the treatment of this devastating disease. Here, we have identified MAP4K4 as a relevant gene for metastasis in PCa. Our work shows that genetic deletion of MAP4K4 or pharmacological inhibition of its encoded kinase, HGK, inhibits metastatic PCa cells migration and clonogenic properties. Hence, MAP4K4 might promote metastasis and tumor growth. Mechanistically, our results indicate that HGK depleted cells exhibit profound differences in F-actin organization, increasing cell spreading and focal adhesion stability. Additionally, HGK depleted cells fails to respond to TNF-α stimulation and chemoattractant action. Moreover, here we show that HGK upregulation in PCa samples from TCGA and other databases correlates with a poor prognosis of the disease. Hence, we suggest that it could be used as prognostic biomarker to predict the appearance of an aggressive phenotype of PCa tumors and ultimately, the appearance of metastasis. In summary, our results highlight an essential role for HGK in the dissemination of PCa cells and its potential use as prognostic biomarker.

GSK-3β Regulates the Expression of P21 to Promote the Progression of Chordoma

Purpose

Chordoma is a rare malignant bone tumor transformed from the remnants of notochord. It is characterized as highly aggressive and locally invasive, difficult to be completely removed by surgery, and has a poor clinical prognosis. Glycogen synthase kinase 3 beta (GSK-3β) is involved in many cellular processes. GSK-3β overexpression has been shown to promote the development of many cancers, according to previous studies. However, the role of GSK-3β in chordoma remains unclear.

Methods

Immunohistochemistry (IHC) and Western blotting (WB) were performed on clinical specimens to measure GSK-3β expression in chordoma, and immunofluorescence and quantitative real-time polymerase chain reaction (QRT-PCR) were performed to examine the expression of GSK-3β and P21 in cell lines. Cell proliferation was detected by the CCK-8 assay and colony formation analysis, cell migration and invasion checked by Transwell experiments, and cell apoptosis was determined by Annexin V/propidium iodide staining. P21 was predicted as a downstream target gene of GSK-3β using STRING and UNIHI databases. Moreover, we used immunoprecipitation to confirm that GSK-3β and P21 interacted with each other. The double luciferase reporter gene assay showed that GSK-3β could regulate the promoter activity of P21. Finally, the role of the GSK-3β -P21 pathway in chordoma tumorigenesis was analyzed in vivo in nude mice.

Results

Our study showed that GSK-3β was significantly higher in chordoma tissues than in paracancer tissues, and siRNA knockdown of GSK-3β inhibited chordoma cell proliferation and promoted cell apoptosis. Additionally, our research found that GSK-3β bound and downregulated the expression of the P21 gene, and the expression of silencing P21 partially reversed the inhibitory effect of knockdown GSK-3β on chordoma. Furthermore, xenografts showed that knockdown GSK-3β inhibited the formation of chordomas in vivo.

Conclusion

Our results indicated that the GSK-3β-P21 axis may be an important signaling pathway for the occurrence and development of chordoma, providing a new therapeutic target for the clinical treatment of this disorder.

The Landscape of Glycogen Synthase Kinase-3 Beta Genomic Alterations in Cancer

Glycogen synthase kinase-3β (GSK-3β), a serine/threonine kinase, has been implicated in the pathogenesis of many cancers, with involvement in cell-cycle regulation, apoptosis, and immune response. Small-molecule GSK-3β inhibitors are currently undergoing clinical investigation. Tumor sequencing has revealed genomic alterations in GSK-3β, yet an assessment of the genomic landscape in malignancies is lacking. This study assessed >100,000 tumors from two databases to analyze GSK-3β alterations. GSK-3β expression and immune cell infiltrate data were analyzed across cancer types, and programmed death-ligand 1 (PD-L1) expression was compared between GSK-3β-mutated and wild-type tumors. GSK-3β was mutated at a rate of 1%. The majority of mutated residues were in the kinase domain, with frequent mutations occurring in a GSK-3β substrate binding pocket. Uterine endometrioid carcinoma was the most commonly mutated (4%) tumor, and copy-number variations were most commonly observed in squamous histologies. Significant differences across cancer types for GSK-3β-mutated tumors were observed for B cells (P = 0.018), monocytes (P = 0.002), dendritic cells (P = 0.005), neutrophils (P = 0.0003), and endothelial cells (P = 0.014). GSK-3β mRNA expression was highest in melanoma. The frequency of PD-L1 expression was higher among GSK-3β-mutated tumors compared with wild type in colorectal cancer (P = 0.03), endometrial cancer (P = 0.05), melanoma (P = 0.02), ovarian carcinoma (P = 0.0001), and uterine sarcoma (P = 0.002). Overall, GSK-3β molecular alterations were detected in approximately 1% of solid tumors, tumors with GSK-3β mutations displayed a microenvironment with increased infiltration of B cells, and GSK-3β mutations were associated with increased PD-L1 expression in selected histologies. These results advance the understanding of GSK-3β complex signaling network interfacing with key pathways involved in carcinogenesis and immune response.

Glycogen Synthase Kinase 3β in Cancer Biology and Treatment

Glycogen synthase kinase (GSK)3β is a multifunctional serine/threonine protein kinase with more than 100 substrates and interacting molecules. GSK3β is normally active in cells and negative regulation of GSK3β activity via phosphorylation of its serine 9 residue is required for most normal cells to maintain homeostasis. Aberrant expression and activity of GSK3β contributes to the pathogenesis and progression of common recalcitrant diseases such as glucose intolerance, neurodegenerative disorders and cancer. Despite recognized roles against several proto-oncoproteins and mediators of the epithelial–mesenchymal transition, deregulated GSK3β also participates in tumor cell survival, evasion of apoptosis, proliferation and invasion, as well as sustaining cancer stemness and inducing therapy resistance. A therapeutic effect from GSK3β inhibition has been demonstrated in 25 different cancer types. Moreover, there is increasing evidence that GSK3β inhibition protects normal cells and tissues from the harmful effects associated with conventional cancer therapies. Here, we review the evidence supporting aberrant GSK3β as a hallmark property of cancer and highlight the beneficial effects of GSK3β inhibition on normal cells and tissues during cancer therapy. The biological rationale for targeting GSK3β in the treatment of cancer is also discussed at length.

Small Molecular Immune Modulators as Anticancer Agents

After decades of intense effort, immune checkpoint inhibitors have been conclusively demonstrated to be effective in cancer treatments and thus are revolutionizing the concepts in the treatment of cancers. Immuno-oncology has arrived and will play a key role in cancer treatment in the foreseeable future. However, efforts to find novel methods to improve the immune response to cancer have not ceased. Small-molecule approaches offer inherent advantages over biologic immunotherapies since they can cross cell membranes, penetrate into tumor tissue and tumor microenvironment more easily, and are amenable to be finely controlled than biological agents, which may help reduce immune-related adverse events seen with biologic therapies and provide more flexibility for the combination use with other therapies and superior clinical benefit. On the one hand, small-molecule therapies can modulate the immune response to cancer by restoring the antitumor immunity, promoting more effective cytotoxic lymphocyte responses, and regulating tumor microenvironment, either directly or epigenetically. On the other hand, the combination of different mechanisms of small molecules with antibodies and other biologics demonstrated admirable synergistic effect in clinical settings for cancer treatment and may expand antibodies' usefulness for broader clinical applications. This chapter provides an overview of small-molecule immunotherapeutic approaches either as monotherapy or in combination for the treatment of cancer.

Nitric Oxide Donor DETA/NO Inhibits the Growth of Endometrial Cancer Cells by Upregulating the Expression of RASSF1 and CDKN1A

Nitric oxide (NO) is implicated in several biological processes, including cancer progression. At low concentrations, it promotes cell survival and tumor progression, and at high concentrations it causes apoptosis and cell death. Until now, the impact of NO donors has not been investigated on human endometrial tumors. Four cancer cell lines were exposed to different concentrations of DETA/NO for 24 to 120 h. The effects of DETA/NO on cell proliferation and invasion were determined utilizing MTS and Boyden chamber assays, respectively. The DETA/NO induced a dose and time-dependent reduction in cell viability by the activation of caspase-3 and cell cycle arrest at the G0/G1 phase that was associated with the attenuated expression of cyclin-D1 and D3. Furthermore, the reduction in the amount of CD133-expressing cancer stem-like cell subpopulation was observed following DETA/NO treatment of cells, which was associated with a decreased expression of stem cell markers and attenuation of cell invasiveness. To understand the mechanisms by which DETA/NO elicits anti-cancer effects, RNA sequencing (RNA-seq) was used to ascertain alterations in the transcriptomes of human endometrial cancer cells. RNA-seq analysis revealed that 14 of the top 21 differentially expressed genes were upregulated and seven were downregulated in endometrial cancer cells with DETA/NO. The genes that were upregulated in all four cell lines with DETA/NO were the tumor suppressors Ras association domain family 1 isoform A (RASSF1) and Cyclin-dependent kinase inhibitor 1A (CDKN1A). The expression patterns of these genes were confirmed by Western blotting. Taken together, the results provide the first evidence in support of the anti-cancer effects of DETA/NO in endometrial cancer.

PNU-74654 enhances the antiproliferative effects of 5-FU in breast cancer and antagonizes thrombin-induced cell growth via the Wnt pathway

The Wnt/β-catenin pathway is one of the most common pathways dysregulated in breast cancer, and may, therefore, be a potential-therapeutic target. We have investigated the effects of PNU-74654 in breast cancer, as a Wnt/β-catenin inhibitor, either alone or in combination with fluorouracil (5-FU). PNU-74654 suppressed cell growth at an IC 50 of 122 ± 0.4 μmol/L and synergistically enhanced the antiproliferative activity of gemcitabine by modulating the Wnt pathway. Using a 3D cell culture model, we found that the PNU-74654 caused tumor shrinkage. It reduced the migration of MCF-7 cells (by an 18% reduction in invasive behavior) after the treatment with PNU-74654 through perturbation of E-cadherin and MMP3/9. PNU-74654/5-FU combination enhanced the percentages of cells in S-phase and significantly increased apoptosis. Moreover, our data showed that this agent was able to inhibit the growth of tumor in a xenograft model, although this effect was more pronounced in the animals treated with PNU-74654 plus 5-FU. These data show the ability of PNU-74654 to specifically target Wnt pathway, interfere with cell proliferation, induce-apoptosis, reduce-migration, and synergistically interact with 5-FU, supporting further studies on this novel therapeutic-approach for breast cancer.

Cellular and Molecular Mechanisms Underlying Prostate Cancer Development: Therapeutic Implications

Prostate cancer is the most frequent nonskin cancer and second most common cause of cancer-related deaths in man. Prostate cancer is a clinically heterogeneous disease with many patients exhibiting an aggressive disease with progression, metastasis, and other patients showing an indolent disease with low tendency to progression. Three stages of development of human prostate tumors have been identified: intraepithelial neoplasia, adenocarcinoma androgen-dependent, and adenocarcinoma androgen-independent or castration-resistant. Advances in molecular technologies have provided a very rapid progress in our understanding of the genomic events responsible for the initial development and progression of prostate cancer. These studies have shown that prostate cancer genome displays a relatively low mutation rate compared with other cancers and few chromosomal loss or gains. The ensemble of these molecular studies has led to suggest the existence of two main molecular groups of prostate cancers: one characterized by the presence of ERG rearrangements (~50% of prostate cancers harbor recurrent gene fusions involving ETS transcription factors, fusing the 5' untranslated region of the androgen-regulated gene TMPRSS2 to nearly the coding sequence of the ETS family transcription factor ERG) and features of chemoplexy (complex gene rearrangements developing from a coordinated and simultaneous molecular event), and a second one characterized by the absence of ERG rearrangements and by the frequent mutations in the E3 ubiquitin ligase adapter SPOP and/or deletion of CDH1, a chromatin remodeling factor, and interchromosomal rearrangements and SPOP mutations are early events during prostate cancer development. During disease progression, genomic and epigenomic abnormalities accrued and converged on prostate cancer pathways, leading to a highly heterogeneous transcriptomic landscape, characterized by a hyperactive androgen receptor signaling axis.

Glycogen synthase kinase-3 beta inhibitors as novel cancer treatments and modulators of antitumor immune responses

As a kinase at the crossroads of numerous metabolic and cell growth signaling pathways, glycogen synthase kinase-3 beta (GSK-3β) is a highly desirable therapeutic target in cancer. Despite its involvement in pathways associated with the pathogenesis of several malignancies, no selective GSK-3β inhibitor has been approved for the treatment of cancer. The regulatory role of GSK-3β in apoptosis, cell cycle, DNA repair, tumor growth, invasion, and metastasis reflects the therapeutic relevance of this target and provides the rationale for drug combinations. Emerging data on GSK-3β as a mediator of anticancer immune response also highlight the potential clinical applications of novel selective GSK-3β inhibitors that are entering clinical studies. This manuscript reviews the preclinical and early clinical results with GSK-3β inhibitors and delineates the developmental therapeutics landscape for this potentially important target in cancer therapy.

Proton pump inhibitors promote the growth of androgen-sensitive prostate cancer cells through ErbB2, ERK1/2, PI3K/Akt, GSK-3β signaling and inhibition of cellular prostatic acid phosphatase

Prostate cancer (PCa) is one of the most common cancer in men. Although hormone-sensitive PCa responds to androgen-deprivation, there are no effective therapies for castration-resistant PCa. It has been recently suggested that proton pump inhibitors (PPIs) may increase the risk of certain cancers; however, association with PCa remains elusive. Here, we evaluated the tumorigenic activities of PPIs in vitro, in PCa cell lines and epithelial cells from benign prostatic hyperplasia (BPH) and in vivo, in PCa mice xenografts. PPIs increased survival and proliferation, and inhibited apoptosis in LNCaP cells. These effects were attenuated or absent in androgen-insensitive DU-145 and PC3 cells, respectively. Specifically, omeprazole (OME) promoted cell cycle progression, increased c-Myc expression, ErbB2 activity and PSA secretion. Furthermore, OME induced the phosphorylation of MAPK-ERK1/2, PI3K/Akt and GSK-3β, and blunted the expression and activity of cellular prostatic acid phosphatase. OME also increased survival, proliferation and PSA levels in BPH cells. In vivo, OME promoted tumor growth in mice bearing LNCaP xenografts. Our results indicate that PPIs display tumorigenic activities in PCa cells, suggesting that their long-term administration in patients should be carefully monitored.

Therapeutic Targeting of CD146/MCAM Reduces Bone Metastasis in Prostate Cancer

Prostate Cancer is the most common cancer and the second leading cause of cancer-related death in males. When prostate cancer acquires castration resistance, incurable metastases, primarily in the bone, occur. The aim of this study is to test the applicability of targeting melanoma cell adhesion molecule (MCAM; CD146) with a mAb for the treatment of lytic prostate cancer bone metastasis. We evaluated the effect of targeting MCAM using in vivo preclinical bone metastasis models and an in vitro bone niche coculture system. We utilized FACS, cell proliferation assays, and gene expression profiling to study the phenotype and function of MCAM knockdown in vitro and in vivo. To demonstrate the impact of MCAM targeting and therapeutic applicability, we employed an anti-MCAM mAb in vivo. MCAM is elevated in prostate cancer metastases resistant to androgen ablation. Treatment with DHT showed MCAM upregulation upon castration. We investigated the function of MCAM in a direct coculture model of human prostate cancer cells with human osteoblasts and found that there is a reduced influence of human osteoblasts on human prostate cancer cells in which MCAM has been knocked down. Furthermore, we observed a strongly reduced formation of osteolytic lesions upon bone inoculation of MCAM-depleted human prostate cancer cells in animal model of prostate cancer bone metastasis. This phenotype is supported by RNA sequencing (RNA-seq) analysis. Importantly, in vivo administration of an anti-MCAM human mAb reduced the tumor growth and lytic lesions. These results highlight the functional role for MCAM in the development of lytic bone metastasis and suggest that MCAM is a potential therapeutic target in prostate cancer bone metastasis. IMPLICATIONS: This study highlights the functional application of an anti-MCAM mAb to target prostate cancer bone metastasis.

An ex vivo Tissue Culture Model for the Assessment of Individualized Drug Responses in Prostate and Bladder Cancer

Urological malignancies, including prostate and bladder carcinoma, represent a major clinical problem due to the frequent occurrence of therapy resistance and the formation of incurable distant metastases. As a result, there is an urgent need for versatile and predictive disease models for the assessment of the individualized drug response in urological malignancies. Compound testing on ex vivo cultured patient-derived tumor tissues could represent a promising approach. In this study, we have optimized an ex vivo culture system of explanted human prostate and bladder tumors derived from clinical specimens and human cancer cell lines xenografted in mice. The explanted and cultured tumor slices remained viable and tissue architecture could be maintained for up to 10 days of culture. Treatment of ex vivo cultured human prostate and bladder cancer tissues with docetaxel and gemcitabine, respectively, resulted in a dose-dependent anti-tumor response. The dose-dependent decrease in tumor cells upon administration of the chemotherapeutic agents was preceded by an induction of apoptosis. The implementation and optimization of the tissue slice technology may facilitate the assessment of anti-tumor efficacies of existing and candidate pharmacological agents in the complex multicellular neoplastic tissues from prostate and bladder cancer patients. Our model represents a versatile “near-patient” tool to determine tumor-targeted and/or stroma-mediated anti-neoplastic responses, thus contributing to the field of personalized therapeutics.

ST6Gal-I overexpression facilitates prostate cancer progression via the PI3K/Akt/GSK-3β/β-catenin signaling pathway

ST6Gal-I sialyltransferase adds α2,6-linked sialic acids to the terminal ends of glycan chains of glycoproteins and glycolipids. ST6Gal-I is reportedly upregulated in many cancers, including hepatocellular carcinoma, ovarian cancer and breast cancer. However, the expression and function of ST6Gal-I in prostate cancer (PCa) and the mechanism underlying this function remain largely unknown. In this study, we observed that ST6Gal-I expression was upregulated in human PCa tissues compared to non-malignant prostate tissues. High ST6Gal-I expression was positively correlated with Gleason scores, seminal vesicle involvement and poor survival in patients with PCa. ST6Gal-I knockdown in aggressive prostate cancer PC-3 and DU145 cells significantly inhibited the proliferation, growth, migration and invasion capabilities of these cells. ST6Gal-I knockdown decreased the levels of several PI3K/Akt/GSK-3β/ β-catenin pathway components, such as p-PI3K, (Ser473)p-Akt, (Ser9)p-GSK-3β and β-catenin. Furthermore, targeting this pathway with a PI3K inhibitor or Akt RNA interference decreased p-Akt, p-GSK-3β and β-catenin expression, resulting in decreased PC-3 and DU145 proliferation, migration and invasion. Taken together, these results indicate that ST6Gal-I plays a critical role in cell proliferation and invasion via the PI3K/Akt/GSK-3β/β-catenin signaling pathway during PCa progression and that it might be a promising target for PCa prognosis determination and therapy.

Nestin suppression attenuates invasive potential of endometrial cancer cells by downregulating TGF-β signaling pathway

Nestin, an intermediate filament protein and a stem cell marker is expressed in several tumors. Until recently, little was known about the expression levels and the role of Nestin in endometrial cancer. Compared to the immortalized endometrial epithelial cell line EM-E6/E7-TERT, endometrial cancer cell lines express high to moderate levels of Nestin. Furthermore, endometrial tumors and tumor cell lines have a cancer stem-like cell subpopulation expressing CD133. Among the cancer lines, AN3CA and KLE cells exhibited both a significantly higher number of CD133+ cells and expressed Nestin at higher levels than Ishikawa cells. Knockdown of Nestin in AN3CA and KLE increased cells in G0/G1 phase of the cell cycle, whereas overexpression in Ishikawa decreased cells in G0/G1 phase and increased cells in S-phase. Nestin knockdown cells showed increased p21, p27, and PNCA levels and decreased expression of cyclin-D1 and D3. In contrast, Nestin overexpression revealed an inverse expression pattern of cell cycle regulatory proteins. Nestin knockdown inhibited cancer cell growth and invasive potential by downregulating TGF-β signaling components, MMP-2, MMP-9, vimentin, SNAIL, SLUG, Twist, N-cadherin, and upregulating the epithelial cell marker E-cadherin whereas the opposite was observed with Nestin overexpressing Ishikawa cells. Nestin knockdown also inhibited, while overexpression promoted invadopodia formation and pFAK expression. Knockdown of Nestin significantly reduced tumor volume in vivo. Finally, progesterone inhibited Nestin expression in endometrial cancer cells. These results suggest that Nestin can be a therapeutic target for cancer treatment.

CAPE suppresses migration and invasion of prostate cancer cells via activation of non-canonical Wnt signaling

Prostate cancer (PCa) was the fifth most common cancer overall in the world. More than 80% of patients died from PCa developed bone metastases. Caffeic acid phenethyl ester (CAPE) is a main bioactive component of honeybee hive propolis. Transwell and wound healing assays demonstrated that CAPE treatment suppressed the migration and invasion of PC-3 and DU-145 PCa cells. Gelatin zymography and Western blotting indicated that CAPE treatment reduced the abundance and activity of MMP-9 and MMP-2. Analysis using Micro-Western Array (MWA), a high-throughput antibody-based proteomics platform with 264 antibodies detecting signaling proteins involved in important pathways indicated that CAPE treatment induced receptor tyrosine kinase-like orphan receptor 2 (ROR2) in non-canonical Wnt signaling pathway but suppressed abundance of β-catenin, NF-κB activity, PI3K-Akt signaling, and epithelial-mesenchymal transition (EMT). Overexpression or knockdown of ROR2 suppressed or enhanced cell migration of PC-3 cells, respectively. TCF-LEF promoter binding assay revealed that CAPE treatment reduced canonical Wnt signaling. Intraperitoneal injection of CAPE reduced the metastasis of PC-3 xenografts in tail vein injection nude mice model. Immunohistochemical staining demonstrated that CAPE treatment increased abundance of ROR2 and Wnt5a but decreased protein expression of Ki67, Frizzle 4, NF-κB p65, MMP-9, Snail, β-catenin, and phosphorylation of IκBα. Clinical evidences suggested that genes affected by CAPE treatment (CTNNB1, RELA, FZD5, DVL3, MAPK9, SNAl1, ROR2, SMAD4, NFKBIA, DUSP6, and PLCB3) correlate with the aggressiveness of PCa. Our study suggested that CAPE may be a potential therapeutic agent for patients with advanced PCa.

A novel miR-34a target, protein kinase D1, stimulates cancer stemness and drug resistance through GSK3/β-catenin signaling in breast cancer

One of the properties of human breast cancer cells is cancer stemness, which is characterized by self-renewal capability and drug resistance. Protein kinase D1 (PRKD1) functions as a key regulator of many cellular processes and is downregulated in invasive breast cancer cells. In this study, we found that PRKD1 was upregulated in MCF-7-ADR human breast cancer cells characterized by drug resistance. Additionally, we discovered that PRKD1 expression was negatively regulated by miR-34a binding to the PRKD1 3′-UTR. PRKD1 expression increased following performance of a tumorsphere formation assay in MCF-7-ADR cells. We also found that reduction of PRKD1 by ectopic miR-34a expression or PRKD1 siRNA treatment resulted in suppressed self-renewal ability in breast cancer stem cells. Furthermore, we confirmed that the PRKD1 inhibitor CRT0066101 reduced phosphorylated PKD/PKCμ, leading to suppression of breast cancer stemness through GSK3/β-catenin signaling. PRKD1 inhibition also influenced apoptosis initiation in MCF-7-ADR cells. Tumors from nude mice treated with miR-34a or CRT0066101 showed suppressed tumor growth, proliferation, and induced apoptosis. These results provide evidence that regulation of PRKD1, a novel miR-34a target, contributes to overcoming cancer stemness and drug resistance in human breast cancer.

Protocols for Migration and Invasion Studies in Prostate Cancer

Prostate cancer is the most common malignancy diagnosed in men in the western world. The development of distant metastases and therapy resistance are major clinical problems in the management of prostate cancer patients. In order for prostate cancer to metastasize to distant sites in the human body, prostate cancer cells have to migrate and invade neighboring tissue. Cancer cells can acquire a migratory and invasive phenotype in several ways, including single cell and collective migration. As a requisite for migration, epithelial prostate cancer cells often need to acquire a motile, mesenchymal-like phenotype. This way prostate cancer cells often lose polarity and epithelial characteristics (e.g., expression of E-cadherin homotypic adhesion receptor), and acquire mesenchymal phenotype (for example, cytoskeletal rearrangements, enhanced expression of proteolytic enzymes and other repertory of integrins). This process is referred to as epithelial-to-mesenchymal transition (EMT). Cellular invasion, one of the hallmarks of cancer, is characterized by the movement of cells through a three-dimensional matrix, resulting in remodeling of the cellular environment. Cellular invasion requires adhesion, proteolysis of the extracellular matrix, and migration of cells. Studying the migratory and invasive ability of cells in vitro represents a useful tool to assess the aggressiveness of solid cancers, including those of the prostate.This chapter provides a comprehensive description of the Transwell migration assay, a commonly used technique to investigate the migratory behavior of prostate cancer cells in vitro. Furthermore, we will provide an overview of the adaptations to the Transwell migration protocol to study the invasive capacity of prostate cancer cells, i.e., the Transwell invasion assay. Finally, we will present a detailed description of the procedures required to stain the Transwell filter inserts and quantify the migration and/or invasion.

ALK1Fc Suppresses the Human Prostate Cancer Growth in in Vitro and in Vivo Preclinical Models

Prostate cancer is the second most common cancer in men and lethality is normally associated with the consequences of metastasis rather than the primary tumor. Therefore, targeting the molecular pathways that underlie dissemination of primary tumor cells and the formation of metastases has a great clinical value. Bone morphogenetic proteins (BMPs) play a critical role in tumor progression and this study focuses on the role of BMP9- Activin receptor-Like Kinase 1 and 2 (ALK1 and ALK2) axis in prostate cancer. In order to study the effect of BMP9 in vitro and in vivo on cancer cells and tumor growth, we used a soluble chimeric protein consisting of the ALK1 extracellular domain (ECD) fused to human Fc (ALK1Fc) that prevents binding of BMP9 to its cell surface receptors and thereby blocks its ability to activate downstream signaling. ALK1Fc sequesters BMP9 and the closely related BMP10 while preserving the activation of ALK1 and ALK2 through other ligands. We show that ALK1Fc acts in vitro to decrease BMP9-mediated signaling and proliferation of prostate cancer cells with tumor initiating and metastatic potential. In line with these observations, we demonstrate that ALK1Fc also reduces tumor cell proliferation and tumor growth in vivo in an orthotopic transplantation model, as well as in the human patient derived xenograft BM18. Furthermore, we also provide evidence for crosstalk between BMP9 and NOTCH and find that ALK1Fc inhibits NOTCH signaling in human prostate cancer cells and blocks the induction of the NOTCH target Aldehyde dehydrogenase member ALDH1A1, which is a clinically relevant marker associated with poor survival and advanced-stage prostate cancer. Our study provides the first demonstration that ALK1Fc inhibits prostate cancer progression, identifying BMP9 as a putative therapeutic target and ALK1Fc as a potential therapy. Altogether, these findings support the validity of ongoing clinical development of drugs blocking ALK1 and ALK2 receptor activity.

MiR-410 induces stemness by inhibiting Gsk3β but upregulating β-catenin in non-small cells lung cancer

Our previous research indicated miR-410 played a critical role in promoting the tumorigenesis and development of NSCLC (non-small cells lung cancer). MiR-410 has been recently reported to be crucial for development and differentiation of embryonic stem cells. But it remains elusive whether miR-410 stimulates the stemness of cancer until now. Herein, we identify miR-410 induces the stemness and is associated with the progression of NSCLC. We demonstrate miR-410 increases the levels of stem cells marker Sox2, Oct4, Nanog, CXCR4 as well as lung cancer stem cells surface marker CD44 and CD166. MiR-410 promotes stem cells-like properties such as proliferation, sphere formation, metastasis and chemoresistance. Moreover, Gsk3β is directly targeted and post-transcriptionally downregulated by miR-410. Also, the expression levels of miR-410 and Gsk3β may be correlated to clinicopathological differentiation in NSCLC tumor specimens. Additionally, we demonstrate miR-410 induces stemness through inhibiting Gsk3β but increasing Sox2, Oct4, Nanog and CXCR4, which binds to β-catenin signaling. In conclusion, our findings identify the miR-410/Gsk3β/β-catenin signaling axis is a novel molecular circuit in inducing stemness of NSCLC.

6-bromo-indirubin-3'-oxime (6BIO), a Glycogen synthase kinase-3β inhibitor, activates cytoprotective cellular modules and suppresses cellular senescence-mediated biomolecular damage in human fibroblasts

As genetic interventions or extended caloric restriction cannot be applied in humans, many studies have been devoted to the identification of natural products that can prolong healthspan. 6-bromoindirubin-3′-oxime (6BIO), a hemi-synthetic derivative of indirubins found in edible mollusks and plants, is a potent inhibitor of Glycogen synthase kinase 3β (Gsk-3β). This pleiotropic kinase has been implicated in various age-related diseases including tumorigenesis, neurodegeneration and diabetes. Accordingly, 6BIO has shown anti-tumor and anti-neurodegenerative activities; nevertheless, the potential role of 6BIO in normal human cells senescence remains largely unknown. We report herein that treatment of human diploid skin fibroblasts with 6BIO reduced the oxidative load, conferred protection against oxidative stress-mediated DNA damage, and it also promoted the activation of antioxidant and proteostatic modules; these effects were largely phenocopied by genetic inhibition of Gsk-3. Furthermore, prolonged treatment of cells with 6BIO, although it decreased the rate of cell cycling, it significantly suppressed cellular senescence-related accumulation of biomolecular damage. Taken together, our presented findings suggest that 6BIO is a novel activator of antioxidant responses and of the proteostasis network in normal human cells; moreover, and given the low levels of biomolecules damage in 6BIO treated senescing cells, this compound likely exerts anti-tumor properties.

CRIPTO and its signaling partner GRP78 drive the metastatic phenotype in human osteotropic prostate cancer

CRIPTO (CR-1, TDGF1) is a cell surface/secreted oncoprotein actively involved in development and cancer. Here, we report that high expression of CRIPTO correlates with poor survival in stratified risk groups of prostate cancer (PCa) patients. CRIPTO and its signaling partner glucose-regulated protein 78 (GRP78) are highly expressed in PCa metastases and display higher levels in the metastatic ALDH^high sub-population of PC-3M-Pro4Luc2 PCa cells compared with non-metastatic ALDH^low. Coculture of the osteotropic PC-3M-Pro4Luc2 PCa cells with differentiated primary human osteoblasts induced CRIPTO and GRP78 expression in cancer cells and increases the size of the ALDH^high sub-population. Additionally, CRIPTO or GRP78 knockdown decreases proliferation, migration, clonogenicity and the size of the metastasis-initiating ALDH^high sub-population. CRIPTO knockdown reduces the invasion of PC-3M-Pro4Luc2 cells in zebrafish and inhibits bone metastasis in a preclinical mouse model. These results highlight a functional role for CRIPTO and GRP78 in PCa metastasis and suggest that targeting CRIPTO/GRP78 signaling may have significant therapeutic potential.

Prostate Cancer Stem Cells and Nanotechnology: A Focus on Wnt Signaling

Prostate cancer is the most common cancer among men worldwide. However, current treatments for prostate cancer patients in advanced stage often fail because of relapse. Prostate cancer stem cells (PCSCs) are resistant to most standard therapies, and are considered to be a major mechanism of cancer metastasis and recurrence. In this review, we summarized current understanding of PCSCs and their self-renewal signaling pathways with a specific focus on Wnt signaling. Although multiple Wnt inhibitors have been developed to target PCSCs, their application is still limited by inefficient delivery and toxicity in vivo. Recently, nanotechnology has opened a new avenue for cancer drug delivery, which significantly increases specificity and reduces toxicity. These nanotechnology-based drug delivery methods showed great potential in targeting PCSCs. Here, we summarized current advancement of nanotechnology-based therapeutic strategies for targeting PCSCs and highlighted the challenges and perspectives in designing future therapies to eliminate PCSCs.

Molecular Pathways: Revisiting Glycogen Synthase Kinase-3β as a Target for the Treatment of Cancer

Glycogen synthase kinase-3β (GSK-3β), a serine/threonine protein kinase, is a complex regulator of numerous cellular functions. GSK-3β is a unique kinase which is constitutively active in resting and nonstimulated cells. GSK-3β has been implicated in a wide range of diseases including neurodegeneration, inflammation and fibrosis, noninsulin-dependent diabetes mellitus, and cancer. It is a regulator of NF-κB-mediated survival of cancer cells, which provided a rationale for the development of GSK-3 inhibitors targeting malignant tumors. Recent studies, many of them reported over the past decade, have identified GSK-3β as a potential therapeutic target in more than 15 different types of cancer. Whereas only active GSK-3β is expressed in cancer cell nucleus, aberrant nuclear accumulation of GSK-3β has been identified as a hallmark of cancer cells in malignant tumors of different origin. This review focuses on the preclinical and clinical development of GSK-3 inhibitors and the potential therapeutic impact of targeting GSK-3β in human cancer. Clin Cancer Res; 23(8); 1891-7. ©2017 AACR.

Glycogen synthase kinase-3β is a pivotal mediator of cancer invasion and resistance to therapy

Tumor cell invasion and resistance to therapy are the most intractable biological characteristics of cancer and, therefore, the most challenging for current cancer research and treatment paradigms. Refractory cancers, including pancreatic cancer and glioblastoma, show an inextricable association between the highly invasive behavior of tumor cells and their resistance to chemotherapy, radiotherapy and targeted therapies. These aggressive properties of cancer share distinct cellular pathways that are connected to each other by several molecular hubs. There is increasing evidence to show that glycogen synthase kinase (GSK)‐3β is aberrantly activated in various cancer types and this has emerged as a potential therapeutic target. In many but not all cancer types, aberrant GSK3β sustains the survival, immortalization, proliferation and invasion of tumor cells, while also rendering them insensitive or resistant to chemotherapeutic agents and radiation. Here we review studies that describe associations between therapeutic stimuli/resistance and the induction of pro‐invasive phenotypes in various cancer types. Such cancers are largely responsive to treatment that targets GSK3β. This review focuses on the role of GSK3β as a molecular hub that connects pathways responsible for tumor invasion and resistance to therapy, thus highlighting its potential as a major cancer therapeutic target. We also discuss the putative involvement of GSK3β in determining tumor cell stemness that underpins both tumor invasion and therapy resistance, leading to intractable and refractory cancer with dismal patient outcomes.

MicroRNA-130b improves renal tubulointerstitial fibrosis via repression of Snail-induced epithelial-mesenchymal transition in diabetic nephropathy

MicroRNA-130b (miR-130b) downregulation has been identified in diabetes, but the role and mechanisms for miR-130b in mediating renal tubulointerstitial fibrosis in diabetic nephropathy (DN) remain unknown. We demonstrated that plasma miR-130b downregulation exhibited clinical and biological relevance as it was linked to increased serum creatinine, β2-microglobulin and proteinuria, increased Snail expression and tubulointerstitial fibrosis in renal biopsies of DN patients. MiR-130b inhibitor caused Snail upregulation and enhanced molecular features of epithelial-to-mesenchymal transition (EMT) in high glucose (30 mM) cultured NRK-52E cells. In contrast, miR-130b mimic downregulated Snail expression and increased epithelial hallmarks. Notably, Snail was identified as an miR-130b direct target and inversely correlated with E-CADHERIN expression. Furthermore, the miR-130b-dependent effects were due to Snail suppression that in turn deregulated E-CADHERIN, VIMENTIN, COLLAGEN IV and α-smooth muscle actin (α-SMA), key mediators of EMT. These effects were reproduced in streptozotocin-induced diabetic rats. Thus, we propose a novel role of the miR-130b-SNAIL axis in fostering EMT and progression toward increased tubulointerstitial fibrosis in DN. Detection of plasma miR-130b and its association with SNAIL can be extrapolated to quantifying the severity of renal tubulointerstitial fibrosis. Targeting miR-130b could be evaluated as a potential therapeutic approach for DN.

Identification of metastasis-associated genes in colorectal cancer using metaDE and survival analysis

The aim of the present study was to detect the candidate genes involved in the metastasis of colorectal cancer (CRC). Gene expression profiles of primary and metastatic CRC samples in the GSE14297 and GSE49355 datasets were downloaded from the Gene Expression Omnibus database. Subsequent to processing, Fishers exact test and the metaDE package in R language were applied to screen the differentially expressed genes (DEGs) between primary and metastatic CRC samples. In addition, function and pathway enrichment analysis was performed using online tools in the Database for Annotation, Visualization, and Integrated Discovery resource and common DEGs in GSE14297 and GSE49355 were identified. Their expression values in another dataset, GSE29621, were then collected in order to screen the genes with high standard deviations between primary and metastatic samples, which were considered as candidate metastasis-associated genes. Candidate genes were finally verified by performing survival analysis via the log-rank test. A total of 370 DEGs were screened in GSE14297 and GSE49355, and 77 common DEGs were identified. Upregulated DEGs were mainly enriched in the immune, energy metabolism and drug metabolism-associated functions. Downregulated DEGs were mainly enriched in cell adhesion-associated functions. A total of 12 genes, including the carbonic anhydrase II (CA2), carcinoembryonic antigen-related cell adhesion molecule 7 (CEACAM7), Fc fragment of immunoglobulin G binding protein (FCGBP), and placenta-specific 8 (PLAC8), were the candidate metastasis-associated genes, among which FCGBP expression significantly decreased the overall survival time of patients. The selected candidate metastasis-associated gene, FCGBP, may be used as a potential therapeutic target in patients with metastatic CRC.

A novel genomic alteration of LSAMP associates with aggressive prostate cancer in African American men

Evaluation of cancer genomes in global context is of great interest in light of changing ethnic distribution of the world population. We focused our study on men of African ancestry because of their disproportionately higher rate of prostate cancer (CaP) incidence and mortality. We present a systematic whole genome analyses, revealing alterations that differentiate African American (AA) and Caucasian American (CA) CaP genomes. We discovered a recurrent deletion on chromosome 3q13.31 centering on the LSAMP locus that was prevalent in tumors from AA men (cumulative analyses of 435 patients: whole genome sequence, 14; FISH evaluations, 101; and SNP array, 320 patients). Notably, carriers of this deletion experienced more rapid disease progression. In contrast, PTEN and ERG common driver alterations in CaP were significantly lower in AA prostate tumors compared to prostate tumors from CA. Moreover, the frequency of inter-chromosomal rearrangements was significantly higher in AA than CA tumors. These findings reveal differentially distributed somatic mutations in CaP across ancestral groups, which have implications for precision medicine strategies.

A screen for transcription factor targets of glycogen synthase kinase-3 highlights an inverse correlation of NFκB and androgen receptor signaling in prostate cancer

Expression of Glycogen Synthase Kinase-3 (GSK-3) is elevated in prostate cancer and its inhibition reduces prostate cancer cell proliferation, in part by reducing androgen receptor (AR) signaling. However, GSK-3 inhibition can also activate signals that promote cell proliferation and survival, which may preclude the use of GSK-3 inhibitors in the clinic. To identify such signals in prostate cancer, we screened for changes in transcription factor target DNA binding activity in GSK-3-silenced cells. Among the alterations was a reduction in AR DNA target binding, as predicted from previous studies, and an increase in NFκB DNA target binding. Consistent with the latter, gene silencing of GSK-3 or inhibition using the GSK-3 inhibitor CHIR99021 increased basal NFκB transcriptional activity. Activation of NFκB was accompanied by an increase in the level of the NFκB family member RelB. Conversely, silencing RelB reduced activation of NFκB by CHIR99021. Furthermore, the reduction of prostate cancer cell proliferation by CHIR99021 was potentiated by inhibition of NFκB signaling using the IKK inhibitor PS1145. Finally, stratification of human prostate tumor gene expression data for GSK3 revealed an inverse correlation between NFκB-dependent and androgen-dependent gene expression, consistent with the results from the transcription factor target DNA binding screen. In addition, there was a correlation between expression of androgen-repressed NFκB target genes and reduced survival of patients with metastatic prostate cancer. These findings highlight an association between GSK-3/AR and NFκB signaling and its potential clinical importance in metastatic prostate cancer.

Epithelial Plasticity in Cancer: Unmasking a MicroRNA Network for TGF-β-, Notch-, and Wnt-Mediated EMT

Epithelial-to-mesenchymal transition (EMT) is a reversible process by which cancer cells can switch from a sessile epithelial phenotype to an invasive mesenchymal state. EMT enables tumor cells to become invasive, intravasate, survive in the circulation, extravasate, and colonize distant sites. Paracrine heterotypic stroma-derived signals as well as paracrine homotypic or autocrine signals can mediate oncogenic EMT and contribute to the acquisition of stem/progenitor cell properties, expansion of cancer stem cells, development of therapy resistance, and often lethal metastatic disease. EMT is regulated by a variety of stimuli that trigger specific intracellular signalling pathways. Altered microRNA (miR) expression and perturbed signalling pathways have been associated with epithelial plasticity, including oncogenic EMT. In this review we analyse and describe the interaction between experimentally validated miRs and their target genes in TGF-β, Notch, and Wnt signalling pathways. Interestingly, in this process, we identified a “signature” of 30 experimentally validated miRs and a cluster of validated target genes that seem to mediate the cross talk between TGF-β, Notch, and Wnt signalling networks during EMT and reinforce their connection to the regulation of epithelial plasticity in health and disease.