Depletion of intrinsic expression of Interleukin-8 in prostate cancer cells causes cell cycle arrest, spontaneous apoptosis and increases the efficacy of chemotherapeutic drugs

CXCR1: A Cancer Stem Cell Marker and Therapeutic Target in Solid Tumors

Therapy resistance is a significant concern while treating malignant disease. Accumulating evidence suggests that a subset of cancer cells potentiates tumor survival, therapy resistance, and relapse. Several different pathways regulate these purported cancer stem cells (CSCs). Evidence shows that the inflammatory tumor microenvironment plays a crucial role in maintaining the cancer stem cell pool. Typically, in the case of the tumor microenvironment, inflammatory pathways can be utilized by the tumor to aid in tumor progression; one such pathway is the CXCR1/2 pathway. The CXCR1 and CXCR2 receptors are intricately related, with CXCR1 binding two ligands that also bind CXCR2. They have the same downstream pathways but potentially separate roles in the tumor microenvironment. CXCR1 is becoming more well known for its role as a cancer stem cell identifier and therapeutic target. This review elucidates the role of the CXCR1 axis as a CSC marker in several solid tumors and discusses the utility of CXCR1 as a therapeutic target.

CC Chemokine Receptor 4 (CCR4) as a Possible New Target for Therapy

Chemokines and their receptors participate in many biological processes, including the modulation of neuroimmune interactions. Approximately fifty chemokines are distinguished in humans, which are classified into four subfamilies based on the N-terminal conserved cysteine motifs: CXC, CC, C, and CX3C. Chemokines activate specific receptors localized on the surface of various immune and nervous cells. Approximately twenty chemokine receptors have been identified, and each of these receptors is a seven-transmembrane G-protein coupled receptor. Recent studies provide new evidence that CC chemokine receptor 4 (CCR4) is important in the pathogenesis of many diseases, such as diabetes, multiple sclerosis, asthma, dermatitis, and cancer. This review briefly characterizes CCR4 and its ligands (CCL17, CCL22, and CCL2), and their contributions to immunological and neoplastic diseases. The review notes a significant role of CCR4 in nociceptive transmission, especially in painful neuropathy, which accompanies many diseases. The pharmacological blockade of CCR4 seems beneficial because of its pain-relieving effects and its influence on opioid efficacy. The possibilities of using the CCL2/CCL17/CCL22/CCR4 axis as a target in new therapies for many diseases are also discussed.

Three-Dimensional Growth of Prostate Cancer Cells Exposed to Simulated Microgravity

Prostate cancer metastasis has an enormous impact on the mortality of cancer patients. Factors involved in cancer progression and metastasis are known to be key players in microgravity (µg)-driven three-dimensional (3D) cancer spheroid formation. We investigated PC-3 prostate cancer cells for 30 min, 2, 4 and 24 h on the random positioning machine (RPM), a device simulating µg on Earth. After a 24 h RPM-exposure, the cells could be divided into two groups: one grew as 3D multicellular spheroids (MCS), the other one as adherent monolayer (AD). No signs of apoptosis were visible. Among others, we focused on cytokines involved in the events of metastasis and MCS formation. After 24 h of exposure, in the MCS group we measured an increase in ACTB, MSN, COL1A1, LAMA3, FN1, TIMP1, FLT1, EGFR1, IL1A, IL6, CXCL8, and HIF1A mRNA expression, and in the AD group an elevation of LAMA3, COL1A1, FN1, MMP9, VEGFA, IL6, and CXCL8 mRNAs compared to samples subjected to 1 g conditions. Significant downregulations in AD cells were detected in the mRNA levels of TUBB, KRT8, IL1B, IL7, PIK3CB, AKT1 and MTOR after 24 h. The release of collagen-1α1 and fibronectin protein in the supernatant was decreased, whereas the secretion of IL-6 was elevated in 24 h RPM samples. The secretion of IL-1α, IL-1β, IL-7, IL-2, IL-8, IL-17, TNF-α, laminin, MMP-2, TIMP-1, osteopontin and EGF was not significantly altered after 24 h compared to 1 g conditions. The release of soluble factors was significantly reduced after 2 h (IL-1α, IL-2, IL-7, IL-8, IL-17, TNF-α, collagen-1α1, MMP-2, osteopontin) and elevated after 4 h (IL-1β, IL-2, IL-6, IL-7, IL-8, TNF-α, laminin) in RPM samples. Taken together, simulated µg induced 3D growth of PC-3 cancer cells combined with a differential expression of the cytokines IL-1α, IL-1β, IL-6 and IL-8, supporting their involvement in growth and progression of prostate cancer cells.

Inhibition of Janus Kinase 1 synergizes docetaxel sensitivity in prostate cancer cells

Prostate cancer (PCa) is the second most common malignancy and is the fifth leading cause of cancer mortality among men globally. Docetaxel-based therapy remains the first-line treatment for metastatic castration-resistant prostate cancer. However, dose-limiting toxicity including neutropenia, myelosuppression and neurotoxicity is the major reason for docetaxel dose reductions and fewer cycles administered, despite a recent study showing a clear survival benefit with increased total number of docetaxel cycles in PCa patients. Although previous studies have attempted to improve the efficacy and reduce docetaxel toxicity through drug combination, no drug has yet demonstrated improved overall survival in clinical trial, highlighting the challenges of improving the activity of docetaxel monotherapy in PCa. Herein, we identified 15 lethality hits for which inhibition could enhance docetaxel sensitivity in PCa cells via a high-throughput kinome-wide loss-of-function screen. Further drug-gene interactions analyses identified Janus kinase 1 (JAK1) as a viable druggable target with existing experimental inhibitors and FDA-approved drugs. We demonstrated that depletion of endogenous JAK1 enhanced docetaxel-induced apoptosis in PCa cells. Furthermore, inhibition of JAK1/2 by baricitinib and ruxolitinib synergizes docetaxel sensitivity in both androgen receptor (AR)-negative DU145 and PC3 cells, but not in the AR-positive LNCaP cells. In contrast, no synergistic effects were observed in cells treated with JAK2-specific inhibitor, fedratinib, suggesting that the synergistic effects are mainly mediated through JAK1 inhibition. In conclusion, the combination therapy with JAK1 inhibitors and docetaxel could be a useful therapeutic strategy in the treatment of prostate cancers.

Prognostic Value of High-Sensitivity Modified Glasgow Prognostic Score in Castration-Resistant Prostate Cancer Patients Who Received Docetaxel

Simple Summary

Prostate cancer is one of the most prevalent cancers in men. Prostate cancer is characterized by an early response to hormonal therapy and prostate-specific antigen (PSA) is useful for diagnosis, prognosis, and treatment evaluation. However, if the patient becomes resistant to treat and develops castration-resistant prostate cancer (CRPC), it is difficult to predict prognosis and evaluate response to treatment using PSA alone. In this study, we found that the high-sensitivity modified Glasgow prognostic score (Hs-mGPS), an inflammatory response score, is a more powerful prognostic factor for CRPC than the modified Glasgow prognostic score (mGPS) previously studied. Furthermore, we suggest that risk classification using Hs-mGPS, PSA, and testosterone (TST) may be a useful tool to predict the prognosis of late staged CRPC.

Abstract

The Glasgow prognostic score, a marker of systemic inflammation, is associated with clinical outcomes in different cancers including prostate cancer. However, there is no evidence for the relationship between the high-sensitivity modified Glasgow prognostic score (Hs-mGPS) in prostate cancer and its prognosis. This study aimed to investigate the prognostic significance of Hs-mGPS in castration-resistant prostate cancer (CRPC) treated with docetaxel. We retrospectively analyzed clinical datasets from 131 CRPC patients who received docetaxel treatment at Chiba University Hospital and a related hospital. Clinical factors including Hs-mGPS before docetaxel treatment were evaluated according to overall survival. The numbers of patients with Hs-mGPS of 0, 1, and 2 were 88, 30, and 13, respectively. The median prostate-specific antigen (PSA) level was 28.9 ng/mL. The median testosterone level was 13.0 ng/dL. The percentages of bone and visceral metastases were 80.8% and 10.2%, respectively. For overall survival, Hs-mGPS ≥ 1 (hazard ratio of 2.41; p = 0.0048), testosterone ≥ 13.0 ng/dL (hazard ratio of 2.23; p = 0.0117), and PSA ≥ 28.9 ng/mL (hazard ratio of 2.36; p = 0.0097) were significant poor prognostic factors in the multivariate analysis. The results of the two-group analysis showed that a higher Hs-mGPS was associated with high PSA, alkaline phosphatase, and testosterone levels. The median testosterone levels for Hs-mGPS of 0, 1, and 2 were 9.0, 16.5, and 23.0, respectively. Based on the multivariate analysis, we created a combined score with three prognostic factors: Hs-mGPS, testosterone, and PSA. The low-risk group (score of 0–1) showed a significantly longer overall survival compared to the intermediate-risk (score of 2–3) and high-risk (score of 4) groups (p < 0.0001). Our results demonstrated that an elevated Hs-mGPS was an independent prognostic factor in CRPC patients treated with docetaxel therapy. Risk classification based on Hs-mGPS, testosterone, and PSA may be useful in predicting the prognosis of CRPC patients.

Impact of baseline serum IL-8 on metastatic hormone-sensitive prostate cancer outcomes in the Phase 3 CHAARTED trial (E3805)

BACKGROUND

The immunosuppressive cytokine interleukin- 8 (IL-8), produced by tumor cells and some myeloid cells, promotes inflammation, angiogenesis, and metastasis. In our discovery work, elevated serum IL-8 at androgen deprivation therapy (ADT) initiation portended worse overall survival (OS). Leveraging serum samples from the phase 3 CHAARTED trial of patients treated with ADT +/- docetaxel for metastatic hormone-sensitive prostate cancer (mHSPC), we validated these findings.

METHODS

Two hundred and thirty-three patients had serum samples drawn within 28 days of ADT initiation. The samples were assayed using the same Mesoscale Multiplex ELISA platform employed in the discovery cohort. After adjusting for performance status, disease volume, and de novo/metachronous metastases, multivariable Cox proportional hazards models assessed associations between IL-8 as continuous and binary variables on OS and time to castration-resistant prostate cancer (CRPC). The median IL-8 level (9.3 pg/ml) was the a priori binary cutpoint. Fixed-effects meta-analyses of the discovery and validation sets were performed.

RESULTS

Higher IL-8 levels were prognostic for shorter OS (continuous: hazard ratio [HR] 2.2, 95% confidence interval [CI]: 1.4-3.6, p = .001; binary >9.3: HR 1.7, 95% CI: 1.2-2.4, p = .007) and time to CRPC (continuous: HR 2.3, 95% CI: 1.6-3.3, p < .001; binary: HR 1.8, 95% CI: 1.3-2.5, p < .001) and independent of docetaxel use, disease burden, and time of metastases. Meta-analysis including the discovery cohort, also showed that binary IL-8 levels >9.3 pg/ml from patients treated with ADT alone was prognostic for poorer OS (HR 1.8, 95% CI: 1.2-2.7, p = .007) and shorter time to CRPC (HR 1.4, 95% CI: 0.99-1.9, p = .057).

CONCLUSIONS

In the phase 3 CHAARTED study of men with mHSPC at ADT initiation, elevated IL-8 portended worse survival and shorter time to castration-resistant prostate cancer independent of docetaxel administration, metastatic burden, and metachronous versus de novo metastatic presentation. These findings support targeting IL-8 as a strategy to improve mHSPC outcomes.

Taxane-induced Attenuation of the CXCR2/BCL-2 Axis Sensitizes Prostate Cancer to Platinum-based Treatment

BACKGROUND

Taxanes are the most active chemotherapy agents in metastatic castration-resistant prostate cancer (mCRPC) patients; yet, resistance occurs almost invariably, representing an important clinical challenge. Taxane-platinum combinations have shown clinical benefit in a subset of patients, but the mechanistic basis and biomarkers remain elusive.

OBJECTIVE

To identify mechanisms and response indicators for the antitumor efficacy of taxane-platinum combinations in mCRPC.

DESIGN, SETTING, AND PARTICIPANTS

Transcriptomic data from a publicly available mCRPC dataset of taxane-exposed and taxane-naïve patients were analyzed to identify response indicators and emerging vulnerabilities. Functional and preclinical validation was performed in taxane-resistant mCRPC cell lines and genetically engineered mouse models (GEMMs).

INTERVENTION

Metastatic CRPC cells were treated with docetaxel, cisplatin, carboplatin, the CXCR2 antagonist SB265610, and the BCL-2 inhibitor venetoclax. Gain and loss of function in culture of CXCR2 and BCL-2 were achieved by overexpression or siRNA silencing. Preclinical assays in GEMM mice tested the antitumor efficacy of taxane-platinum combinations.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Proliferation, apoptosis, and colony assays measured drug activity in vitro. Preclinical endpoints in mice included growth, survival, and histopathology. Changes in CXCR2, BCL-2, and chemokines were analyzed by reverse transcriptase quantitative polymerase chain reaction and Western blot. Human expression data were analyzed using Gene Set Enrichment Analysis, hierarchical clustering, and correlation studies. GraphPad Prism software and R-studio were used for statistical and data analyses.

RESULTS AND LIMITATIONS

Transcriptomic data from taxane-exposed human mCRPC tumors correlate with a marked negative enrichment of apoptosis and inflammatory response pathways accompanied by a marked downregulation of CXCR2 and BCL-2. Mechanistically, we show that docetaxel inhibits CXCR2 and that BCL-2 downregulation occurs as a downstream effect. Further, we demonstrated in experimental models that the sensitivity to cisplatin is dependent on CXCR2 and BCL-2, and that targeting them sensitizes prostate cancer (PC) cells to cisplatin. In vivo taxane-platinum combinations are highly synergistic, and previous exposure to taxanes sensitizes mCRPC tumors to second-line cisplatin treatment.

CONCLUSIONS

The hitherto unappreciated attenuation of the CXCR2/BCL-2 axis in taxane-treated mCRPC patients is an acquired vulnerability with potential predictive activity for platinum-based treatments.

PATIENT SUMMARY

A subset of patients with aggressive and therapy-resistant prostate cancer benefits from taxane-platinum combination chemotherapy; however, we lack the mechanistic understanding of how that synergistic effect occurs. Here, using patient data and preclinical models, we found that taxanes reduce cancer cell escape mechanisms to chemotherapy-induced cell death, hence making these cells more vulnerable to additional platinum treatment.

[Menthol enhances interleukin-13-induced synthesis and secretion of mucin 5AC in human bronchial epithelial cells]

OBJECTIVE

To investigate the effect of interleukin (IL) -13 combined with cold stimulation on synthesis and secretion of mucin (MUC) 5AC in human bronchial epithelial cell line 16HBE and explore the role of transient receptor potential 8 (TRPM8) and anti-apoptotic factor B-cell lymphoblast-2 (Bcl-2) in this process.

METHODS

16HBE cells were stimulated with 10 ng/mL IL-13, 1 mmol/L menthol, or both (1 mmol/L menthol was added after 6 days of IL-13 stimulation), and the changes in the expression of MUC5AC, intracellular Ca²⁺ concentration and Bcl-2 expression were evaluated. The effects of ABT-263 (a Bcl-2 inhibitor) and BCTC (a TRPM8 ion channel inhibitor), alone or in combination, on MUC5AC expression in the cells were tested, and the changes in intracellular Ca²⁺ and Bcl-2 expression following BCTC treatment were observed. The cell viability was assessed using CCK-8 assay, the mRNA expressions of MUC5AC and Bcl-2 were detected with real-time quantitative PCR, the level of MUC5AC in the culture medium was measured with ELISA, and the intracellular Ca²⁺ fluorescence intensity was determined with flow cytometry.

RESULTS

The mRNA and protein expressions of MUC5AC increased significantly in 16HBE cells following stimulation with IL-13, menthol, and both (P < 0.05), and were the highest in the combined treatment group with its peak level occurred at 24 h (P < 0.01). The intracellular Ca²⁺ fluorescence intensity and Bcl-2 mRNA expression were also increased in 16HBE cells after the stimulations (P < 0.05), and the increments were the most obvious in the combined treatment group (P < 0.01). Treatment with BCTC significantly lowered intracellular Ca²⁺ fluorescence intensity and the expressions of Bcl-2 and MUC5AC mRNA and protein in the cells stimulated with menthol or with both IL-13 and menthol (P < 0.05), but caused no significant changes in IL-13-stimulated cells (P > 0.05). Treatment with ABT-263 significantly lowered the mRNA and protein expressions of MUC5AC in the cells stimulated with IL-13 and menthol either alone or in combination (P < 0.05).

CONCLUSIONS

Menthol combined with IL-13 produces a synergistic effect to promote the synthesis and secretion of MUC5AC in 16HBE cells possibly by activating TRPM8 receptor to upregulate the expression of Bcl-2.

Promotion of epithelial hyperplasia by interleukin-8-CXCR axis in human prostate

BACKGROUND

The clinical manifestation of benign prostatic hyperplasia (BPH) is causally linked to the inflammatory microenvironment and proliferation of epithelial and stromal cells in the prostate transitional zone. The CXC-chemokine interleukin-8 (IL-8) contributes to inflammation. We evaluated the expression of inflammatory cytokines in clinical specimens, primary cultures, and prostatic lineage cell lines. We investigated whether IL-8 via its receptor system (IL-8 axis) promotes BPH.

METHODS

The messenger RNA and protein expression of chemokines, including components of the IL-8 axis, were measured in normal prostate (NP; n = 7) and BPH (n = 21), urine (n = 24) specimens, primary cultures, prostatic lineage epithelial cell lines (NHPrE1, BHPrE1, BPH-1), and normal prostate cells (RWPE-1). The functional role of the IL-8 axis in prostate epithelial cell growth was evaluated by CRISPR/Cas9 gene editing. The effect of a combination with two natural compounds, oleanolic acid (OA) and ursolic acid (UA), was evaluated on the expression of the IL-8 axis and epithelial cell growth.

RESULTS

Among the 19 inflammatory chemokines and chemokine receptors we analyzed, levels of IL-8 and its receptors (CXCR1, CXCR2), as well as, of CXCR7, a receptor for CXCL12, were 5- to 25-fold elevated in BPH tissues when compared to NP tissues (P ≤ .001). Urinary IL-8 levels were threefold to sixfold elevated in BPH patients, but not in asymptomatic males and females with lower urinary tract symptoms (P ≤ .004). The expression of the IL-8 axis components was confined to the prostate luminal epithelial cells in both normal and BPH tissues. However, these components were elevated in BPH-1 and primary explant cultures as compared to RWPE-1, NHPrE1, and BHPrE1 cells. Knockout of CXCR7 reduced IL-8, and CXCR1 expression by 4- to 10-fold and caused greater than or equal to 50% growth inhibition in BPH-1 cells. Low-dose OA + UA combination synergistically inhibited the growth of BPH-1 and BPH primary cultures. In the combination, the drug reduction indices for UA and OA were 16.4 and 7852, respectively, demonstrating that the combination was effective in inhibiting BPH-1 growth at significantly reduced doses of UA or OA alone.

CONCLUSION

The IL-8 axis is a promotor of BPH pathogenesis. Low-dose OA + UA combination inhibits BPH cell growth by inducing autophagy and reducing IL-8 axis expression in BPH-epithelial cells.

Withania somnifera (L.) Dunal: A potential therapeutic adjuvant in cancer

ETHNOPHARMACOLOGICAL RELEVANCE

Withania somnifera (L.) Dunal (WS) is one of the moststudied Rasayana botanicals used in Ayurveda practice for its immunomodulatory, anti-aging, adaptogenic, and rejuvenating effects. The botanical is being used for various clinical indications, including cancer. Several studies exploring molecular mechanisms of WS suggest its possible role in improving clinical outcomes in cancer management. Therefore, research on WS may offer new insights in rational development of therapeutic adjuvants for cancer.

AIM OF THIS REVIEW

The review aims at providing a detailed analysis of in silico, in vitro, in vivo, and clinical studies related to WS and cancer. It suggests possible role of WS in regulating molecular mechanisms associated with carcinogenesis. The review discusses potential of WS in cancer management in terms of cancer prevention, anti-cancer activity, and enhancing efficacy of cancer therapeutics.

MATERIAL AND METHODS

The present narrative review offers a critical analysis of published literature on WS studies in cancer. The reported studies were analysed in the context of pathophysiology of cancer, commonly referred as 'cancer hallmarks'. The review attempts to bridge Ayurveda knowledge with biological insights into molecular mechanisms of cancer.

RESULTS

Critical analysisof the published literature suggests an anti-cancer potential of WS with a key role in cancer prevention. The possible mechanisms for these effects are associated with the modulation of apoptotic, proliferative, and metastatic markers in cancer. WS can attenuate inflammatory responses and enzymes involved in invasion and metastatic progression of cancer.The properties of WS are likely to be mediated through withanolides, which may activate tumor suppressor proteins to restrict proliferation of cancer cells. Withanolides also regulate the genomic instability, and energy metabolism of cancer cells. The reported studies indicate the need for deeper understanding of molecular mechanisms of WS in inhibiting angiogenesis and promoting immunosurveillance. Additionally, WS can augment efficacy and safety of cancer therapeutics.

CONCLUSION

The experimentally-supported evidence of immunomodulatory, anti-cancer, adaptogenic, and regenerative attributes of WS suggest its therapeutic adjuvant potential in cancer management. The adjuvant properties of withanolides can modulate multidrug resistance and reverse chemotherapy-induced myelosuppression. These mechanisms need to be further explored in systematically designed translational and clinical studies that will pave the way for integration of WS as a therapeutic adjuvant in cancer management.

CCL2/CCR2 signaling in cancer pathogenesis

Chemokines are a family of small cytokines, which guide a variety of immune/inflammatory cells to the site of tumor in tumorigenesis. A dysregulated expression of chemokines is implicated in different types of cancer including prostate cancer. The progression and metastasis of prostate cancer involve a complex network of chemokines that regulate the recruitment and trafficking of immune cells. The chemokine CCL2 and its main receptor CCR2 have been receiving particular interest on their roles in cancer pathogenesis. The up-regulation of CCL2/CCR2 and varied immune conditions in prostate cancer, are associated with cancer advancement, metastasis, and relapse. Here we reviewed recent findings, which link CCL2/CCR2 to the inflammation and cancer pathogenesis, and discussed the therapeutic potential of CCL2/CCR2 axis in cancer treatment based on results from our group and other investigators, with a major focus on prostate cancer. Video Abstract.

EHD2 is a Predictive Biomarker of Chemotherapy Efficacy in Triple Negative Breast Carcinoma

EHD2 is a mechanotransducing ATPase localized in caveolae invaginations at the plasma membrane. EHD2 has recently been associated with several human cancers, however the significance of EHD2 transcript levels in cancer prognosis remains debated. Breast cancer is the most commonly occurring cancer in women and prognosis is variable depending on the subtypes. Triple negative breast cancer (TNBC) often has a poor therapeutic response. The aim of this study was to assess the prognostic significance of EHD2 transcripts and protein expression levels in breast carcinomas. We found that low EHD2 levels were associated with enhanced proliferation, migration and invasion of TNBC cells. EHD2 expression was significantly reduced in TNBC tissues and the loss of EHD2 led to higher expression of the pro-tumoral cytokine IL-8. In apparent contradiction with in vitro data, multivariate analysis of two independent cohorts of breast cancer patients revealed that low EHD2 was in fact associated with good prognosis in the highly proliferative TNBC subtype. Accordingly, TNBC low EHD2 expressers were found to benefit the most from chemotherapy when compared to all subtypes of breast cancers. Our study validates EHD2 expression level as an independent prognostic factor of metastasis-free survival and as a new predictive marker of chemotherapy efficacy in TNBC patients.

Stem cell paracrine actions in tissue regeneration and potential therapeutic effect in human endometrium: a retrospective study

OBJECTIVE

Determining genetic and paracrine mechanisms behind endometrial regeneration in Asherman's syndrome and endometrial atrophy (AS/EA) patients after autologous CD133⁺ bone marrow-derived stem cell (CD133⁺ BMDSC) transplantation.

DESIGN

Retrospective study using human endometrial biopsies and mouse models.

SETTING

Fundación-IVI, IIS-La Fe, Valencia, Spain.

SAMPLES

Endometrial biopsies collected before and after CD133⁺ BMDSC therapy, from eight women with AS/EA (NCT02144987) from the uterus of five mice with only left horns receiving CD133⁺ BMDSC therapy.

METHODS

In human samples, haematoxylin and eosin (H&E) staining, RNA arrays, PCR validation, and neutrophil elastase (NE) immunohistochemistry (IHQ). In mouse samples, PCR validation and protein immunoarrays.

MAIN OUTCOME MEASURES

H&E microscopic evaluation, RNA expression levels, PCR, and growth/angiogenic factors quantification, NE IHQ signal.

RESULTS

Treatment improved endometrial morphology and thickness for all patients. In human samples, Jun, Serpine1, and Il4 were up-regulated whereas Ccnd1 and Cxcl8 were down-regulated after treatment. The significant decrease of NE signal corroborated Cxcl8 expression. Animal model analysis confirmed human results and revealed a higher expression of pro-angiogenic cytokines (IL18, HGF, MCP-1, MIP2) in treated uterine horns.

CONCLUSIONS

CD133⁺ BMDSC seems to activate several factors through a paracrine mechanism to help tissue regeneration, modifying endometrial behaviour through an immunomodulatory milieu that precedes proliferation and angiogenic processes. Insight into these processes could bring us one step closer to a non-invasive treatment for AS/EA patients.

TWEETABLE ABSTRACT

CD133⁺ BMDSC therapy regenerates endometrium, modifying the immunological milieu that precedes proliferation and angiogenesis.

Infiltrating CD4+ T cells attenuate chemotherapy sensitivity in prostate cancer via CCL5 signaling

BACKGROUND

Chemotherapy with Docetaxel (Doc) is efficient in a subset of prostate cancer (PCa) cases; however, most patients ultimately develop resistance to Docetaxel. The tumor immune microenvironment and secreted cytokines play a substantial role in development of resistance to chemotherapy. Our previous study has demonstrated that CD4+ T cells in prostate tumor microenvironment contribute to PCa progression; meanwhile, we found increased CD4+ T-cell infiltration in tumor area after Doc treatment; however, their effects on PCa chemosensitivity remain unclear. Here, we aim to explore the role and mechanisms of CD4+ T cells in PCa chemotherapy sensitivity.

METHODS

CD4+ T-cell infiltration in Doc-treated paraffin-embedded specimens from transurethral resection of prostate, radical prostatectomy, or bone metastasis was detected by immunohistochemistry. The castration-resistant PCa cell lines-C4-2 and CWR22RV1, and CD4+ T-cell lines-HH and Molt-3 were used in the coculture system. After coculture with the lymphocytes, PCa cell chemosensitivity was detected by cell counting kit-8, terminal deoxynucleotidyl transferase dUTP nick-end labeling assays, and Western blot analysis. Various cell cytokines were determined by cytokine arrays and reverse-transcription polymerase chain reaction. The recombinant human C-C motif chemokine ligand 5 (CCL5) was added to PCa cells for further confirming its effects and anti-CCL5 antibody was used for neutralization. S3I-201, a signal transducer and activator of transcription 3 (STAT3) inhibitor, was added to the coculture system to detect STAT3 role in chemosensitivity. Tumor xenografts in nude mice were used for confirming effects of CD4+ T cells in vivo study.

RESULTS

We found more infiltrated CD4+ T cells in human PCa lesions than in the adjacent noncancerous tissues after Doc treatment. In vitro cell line study confirmed that CD4+ T cells increase the PCa Doc resistance. Quantative polymerase chain reaction and cytokine arrays indicated that after coculture with PCa, CD4+ T cells could secrete large amounts of CCL5. Moreover, CCL5 stimulation enhanced PCa resistance to Doc, and anti-CCL5 antibody could partly reverse this process. We found that CD4+ T cells could activate P-STAT3 signaling via secreting CCL5 and adding a STAT3 inhibitor can reverse the chemoresistance. In vivo mouse model with xenografted 22RV1 cells and CD4+ T cells also confirmed the in vitro results.

CONCLUSIONS

Together, our results indicate that infiltrating CD4+ T cells could promote PCa chemotherapy resistance via modulation of the CCL5/STAT3 signaling pathway.

Overexpressing miR‑335 inhibits DU145 cell proliferation by targeting early growth response 3 in prostate cancer

MicroRNA-335 (miR-335) was reported to suppress cell proliferation in prostate cancer (PC), a common malignancy in males. The expression of early growth response 3 (EGR3) was determined to be elevated in human PC tissues; however, the possible effects and underlying mechanism of miR-335 on PC remains unknown. In the present study, miR-335 mimics and miR-335 inhibitors were respectively transfected into DU145 cells. Stable silencing of EGR3 was observed in DU145 cells following transfection with small interfering RNA. We also used Cell Counting Kit-8 and in vitro angiogenesis assays to determine the viability and revascularization potential of DU145 cells. The expression levels of EGR and caspase-3 activity were analyzed by immunohistochemistry and immunocytochemistry, respectively. We predicted the target of miR-335 by bioinformatics analysis and a dual-luciferase reporter gene assay. Western blot and quantitative real-time polymerase chain reaction analyses were performed to determine the protein and mRNA expression of molecules. miR-335 expression was downregulated in PC tissues and cell lines. Overexpression of miR-335 significantly reduced the viability and the formation of regenerative tubes of DU145 cells, and inhibited the expression of inflammatory factors. EGR3 was proposed as a possible target of miR-335, and was negatively regulated by miR-335. Silencing EGR3 suppressed the viability and angiogenesis of DU145 cells, and reduced the activity of caspase-3 and inflammatory factor expression. miR-335 inhibition along with EGR3 silencing EGR3 inhibited the cell proliferation. Furthermore, miR-335 inhibited the formation of a PC solid tumor xenograft in vivo. Thus, miR-335 may exert an antitumor effect on DU145 cells by regulating the expression of EGR3. The findings of the present study may provide insight into a novel therapeutic strategy for the treatment of prostatic carcinoma.

Disrupting Inflammation-Associated CXCL8-CXCR1 Signaling Inhibits Tumorigenicity Initiated by Sporadic- and Colitis-Colon Cancer Stem Cells

Dysfunctional inflammatory pathways are associated with an increased risk of cancer, including colorectal cancer. We have previously identified and enriched for a self-renewing, colon cancer stem cell (CCSC) subpopulation in primary sporadic colorectal cancers (CRC) and a related subpopulation in ulcerative colitis (UC) patients defined by the stem cell marker, aldehyde dehydrogenase (ALDH). Subsequent work demonstrated that CCSC-initiated tumors are dependent on the inflammatory chemokine, CXCL8, a known inducer of tumor proliferation, angiogenesis and invasion. Here, we use RNA interference to target CXCL8 and its receptor, CXCR1, to establish the existence of a functional signaling pathway promoting tumor growth initiated by sporadic and colitis CCSCs. Knocking down either CXCL8 or CXCR1 had a dramatic effect on inhibiting both in vitro proliferation and angiogenesis. Likewise, tumorigenicity was significantly inhibited due to reduced levels of proliferation and angiogenesis. Decreased expression of cycle cell regulators cyclins D1 and B1 along with increased p21 levels suggested that the reduction in tumor growth is due to dysregulation of cell cycle progression. Therapeutically targeting the CXCL8-CXCR1 signaling pathway has the potential to block sustained tumorigenesis by inhibiting both CCSC- and pCCSC-induced proliferation and angiogenesis.

Interleukin (IL)-8 polymorphisms and risk of prostate disorders

Prostate cancer (PCa) and benign prostate hyperplasia (BPH) as two prevalent age-related disorders in male have some shared genetic and immunological underlying mechanisms. However, researchers have aimed at identification of specific biomarkers with the ability to differentiate between these disorders. In the present study, we genotyped the rs4073, rs2227306 and rs1126647 single nucleotide polymorphisms within IL-8 gene in 530 individuals including 130 PCa patients, 200 BPH patients and 200 male controls. The rs2227306 alleles and genotypes were distributed equally in the three study groups. The frequency of the A allele of the rs4073 was significantly lower in PCa group compared with BPH group (OR (95% CI) = 0.62 (0.46-0.84), adjusted P value = 0.006). This allele was negatively associated with PCa risk in dominant model (OR (95% CI) = 0.53 (0.34-0.83), adjusted P value = 0.02). When comparing PCa and BPH groups, the rs1126647 was associated with PCa risk in recessive model (OR (95% CI) = 2.14 (1.23-3.72), adjusted P value = 0.02). The A T A haplotype (rs4073, rs2227306 and rs1126647 respectively) was less frequent in PCa group compared with BPH group (OR (95% CI) = 0.4 (0.22-0.75), adjusted P value = 0.03). Consequently, our data demonstrated significant differences in allele, genotype and haplotype frequencies of IL-8 variants between BPH and PCa patients which might imply distinct role for this chemokine in the pathogenesis of these disorders. Future studies are needed to elaborate the underlying mechanism of these observations.

Inhibiting G protein βγ signaling blocks prostate cancer progression and enhances the efficacy of paclitaxel

Aberrant activation of G protein-coupled receptors (GPCRs) is implicated in prostate cancer progression, but targeting them has been challenging because multiple GPCRs are involved in cancer progression. In this study, we tested the effect of blocking signaling via a hub through which multiple GPCRs converge — the G-protein Gβγ subunits. Inhibiting Gβγ signaling in several castration-resistant prostate cancer cell lines (i.e. PC3, DU145 and 22Rv1), impaired cell growth and migration in vitro, and halted tumor growth and metastasis in nude mice. The blockade of Gβγ signaling also diminished prostate cancer stem cell-like activities, by reducing tumorsphere formation in vitro and tumor formation in a limiting dilution assay in nude mice. Furthermore, Gβγ blockade enhanced the sensitivity of prostate cancer cells to paclitaxel treatment, both in vitro and in vivo. Together, our results identify a novel function of Gβγ in regulating prostate cancer stem-cell-like activities, and demonstrate that targeting Gβγ signaling is an effective approach in blocking prostate cancer progression and augmenting response to chemotherapy.

The expression of genes contributing to pancreatic adenocarcinoma progression is influenced by the respective environment

Pancreatic adenocarcinoma is a highly aggressive malignancy with dismal prognosis and limited curative options. We investigated the influence of organ environments on gene expression in RNU rats by orthotopic and intraportal infusion of Suit2-007luc cells into the pancreas, liver and lung respectively. Tumor tissues from these sites were analyzed by chip array and histopathology. Generated data was analyzed by Chipster and Ingenuity Pathway Analysis (±1.5 expression fold change and p<0.05). Further analysis of functional annotations derived from IPA, was based on selected genes with significant modulation of expression. Comparison of groups was performed by creating ratios from the mean expression values derived from pancreas and respective in vitro values, whereas those from liver and lung were related to pancreas, respectively. Genes of interest from three functional annotations for respective organs were identified by exclusion-overlap analyses. From the resulting six genes, transglutaminase2 (TGM2) was further investigated by various assays. Its knockdown with siRNA induced dose dependent inhibitory and stimulatory effects on cell proliferation and cell migration, respectively. DNA fragmentation indicated apoptotic cell death in response to TGM2 knockdown. Cell cycle analysis by FACS showed that TGM2 knockdown induced G1/S blockade. Therefore, TGM2 and its associated genes may be promising therapeutic targets.

Constructing Bayesian networks by integrating gene expression and copy number data identifies NLGN4Y as a novel regulator of prostate cancer progression

To understand the heterogeneity of prostate cancer (PCa) and identify novel underlying drivers, we constructed integrative molecular Bayesian networks (IMBNs) for PCa by integrating gene expression and copy number alteration data from published datasets. After demonstrating such IMBNs with superior network accuracy, we identified multiple sub-networks within IMBNs related to biochemical recurrence (BCR) of PCa and inferred the corresponding key drivers. The key drivers regulated a set of common effectors including genes preferentially expressed in neuronal cells. NLGN4Y—a protein involved in synaptic adhesion in neurons—was ranked as the top gene closely linked to key drivers of myogenesis subnetworks. Lower expression of NLGN4Y was associated with higher grade PCa and an increased risk of BCR. We show that restoration of the protein expression of NLGN4Y in PC-3 cells leads to decreased cell proliferation, migration and inflammatory cytokine expression. Our results suggest that NLGN4Y is an important negative regulator in prostate cancer progression. More importantly, it highlights the value of IMBNs in generating biologically and clinically relevant hypotheses about prostate cancer that can be validated by independent studies.

Inflammatory Cytokine Signaling during Development of Pancreatic and Prostate Cancers

Inflammation is essential for many diseases including cancer. Activation and recruitment of immune cells during inflammation result in a cytokine- and chemokine-enriched cell environment, which affects cancer development. Since each type of cancer has its unique tumor environment, effects of cytokines from different sources such as tumor-infiltrating immune cells, stromal cells, endothelial cells, and cancer cells on cancer development can be quite complex. In this review, how immune cells contribute to tumorigenesis of pancreatic and prostate cancers through their secreted cytokines is discussed. In addition, the cytokine signaling that tumor cells of pancreatic and prostate cancers utilize to benefit their own survival is delineated.

A standardized herbal extract mitigates tumor inflammation and augments chemotherapy effect of docetaxel in prostate cancer

Activation of the NFκB pathway is often associated with advanced cancer and has thus been regarded as a rational therapeutic target. Wedelia chinensis is rich in luteolin, apigenin, and wedelolactone that act synergistically to suppress androgen receptor activity in prostate cancer. Interestingly, our evaluation of a standardized Wedelia chinensis herbal extract (WCE) concluded its efficacy on hormone-refractory prostate cancer through systemic mechanisms. Oral administration of WCE significantly attenuated tumor growth and metastasis in orthotopic PC-3 and DU145 xenografts. Genome-wide transcriptome analysis of these tumors revealed that WCE suppressed the expression of IKKα/β phosphorylation and downstream cytokines/chemokines, e.g., IL6, CXCL1, and CXCL8. Through restraining the cytokines expression, WCE reduced tumor-elicited infiltration of myeloid-derived suppressor cells (MDSCs), tumor-associated macrophages (TAMs) and endothelial cells into the tumors, therefore inhibiting angiogenesis, tumor growth, and metastasis. In MDSCs, WCE also reduced STAT3 activation, downregulated S100A8 expression and prevented their expansion. Use of WCE in combination with docetaxel significantly suppressed docetaxel-induced NFκB activation, boosted the therapeutic effect and reduced the systemic toxicity caused by docetaxel monotherapy. These data suggest that a standardized preparation of Wedelia chinensis extract improved prostate cancer therapy through immunomodulation and has potential application as an adjuvant agent for castration-resistant prostate cancer.

IL‑8 promotes proliferation and inhibition of apoptosis via STAT3/AKT/NF‑κB pathway in prostate cancer

Interleukin-8 (IL-8) possesses tumorigenic and proangiogenic properties, and is overexpressed in many human cancer types. However, only few studies have demonstrated the mechanisms of action of IL‑8 regarding the ability to promote proliferation and to inhibit apoptosis in prostate cancer. Here, the aim of the present study was to investigate the effects of IL‑8 on the prostate cancer cell line and determine possible mechanisms underlying its effect. In this study, IL‑8 was shown to be significantly upregulated in prostate cancer compared with paired normal control tissues. The data showed that IL‑8 exhibits direct oncogenicity, which significantly induced cell proliferation, invasion and attenuated apoptosis in prostate cancer cells via signal transducer and activator of transcription 3/protein kinase B/nuclear factor‑κB signaling pathways. In conclusion, modulation of IL‑8 expression or its associated signaling pathway may provide a novel working mechanism of IL‑8 in prostate cancer, and a promising strategy for controlling the progression and metastasis of prostate cancer.

MicroRNA-181a promotes docetaxel resistance in prostate cancer cells

BACKGROUND

Docetaxel is one of the primary drugs used for treating castration resistant prostate cancer (CRPC). Unfortunately, over time patients invariably develop resistance to docetaxel therapy and their disease will continue to progress. The mechanisms by which resistance develops are still incompletely understood. This study seeks to determine the involvement of miRNAs, specifically miR-181a, in docetaxel resistance in CRPC.

METHODS

Real-time PCR was used to measure miR-181a expression in parental and docetaxel resistant C4-2B and DU145 cells (TaxR and DU145-DTXR). miR-181a expression was modulated in parental or docetaxel resistant cells by transfecting them with miR-181a mimics or antisense, respectively. Following transfection, cell number was determined after 48 h with or without docetaxel. Cross resistance to cabazitaxel induced by miR-181a was also determined. Western blots were used to determine ABCB1 protein expression and rhodamine assays used to assess activity. Phospho-p53 expression was assessed by Western blot and apoptosis was measured by ELISA in C4-2B TaxR and PC3 cells with inhibited or overexpressed miR-181a expression with or without docetaxel.

RESULTS

miR-181a is significantly overexpressed in TaxR and DU145-DTXR cells compared to parental cells. Overexpression of miR-181a in parental cells confers docetaxel and cabazitaxel resistance and knockdown of miR-181a in TaxR cells re-sensitizes them to treatment with both docetaxel and cabazitaxel. miR-181a was not observed to impact ABCB1 expression or activity, a protein which was previously demonstrated to be highly involved in docetaxel resistance. Knockdown of miR-181a in TaxR cells induced phospho-p53 expression. Furthermore, miR-181a knockdown alone induced apoptosis in TaxR cells which could be further enhanced by the addition of DTX.

CONCLUSIONS

Overexpression of mir-181a in prostate cancer cells contributes to their resistance to docetaxel and cabazitaxel and inhibition of mir-181a expression can restore treatment response. This is due, in part, to modulation of p53 phosphorylation and apoptosis.

Withania somnifera targets interleukin-8 and cyclooxygenase-2 in human prostate cancer progression

BACKGROUND

Prostate cancer (PC) is a common noncutaneous malignancy in men. The incidence of PC is increasing at an alarming rate across the globe. Progression of PC is associated with elevated levels of interleukin-8 (IL-8) and cyclooxygenase-2 (COX-2) in malignant cells. Overexpression of these players is accompanied by chronic inflammation, increased angiogenesis, proliferation, migration, and inhibition of apoptosis. Moreover, their elevated circulating levels promote the disease progression from androgen-dependent to androgen-independent state. Thus, inhibiting the expression of IL-8 and COX-2 would be a promising target in the development of PC therapeutics. In this study, we investigated the inhibitory effects of Withania somnifera extract on highly metastatic, androgen-independent prostate cancer cell line (PC3). Additionally, we compared the real-time expression of IL-8 and COX-2 in prostate tissue samples.

MATERIALS AND METHODS

The cell viability and cytotoxicity of W. somnifera extract in PC3 cells was quantified colorimetrically by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide and lactate dehydrogenase leakage assay, respectively. Hematoxylin and eosin staining for histological examination, trypan blue, and acridine orange dyes to enumerate apoptotic and live cells, quantitative real-time polymerase chain reaction to determine the expression and flow cytometry to study the cell cycle analysis were used.

RESULTS

We observed a significant decrease in the cell viability with a half-maximal inhibitory concentration (IC50) of 10 μg/mL. The expression levels of IL-8 and COX-2 in prostate tissue samples and in PC3 cells were predominantly high; however, the lowest dose of W. somnifera significantly inhibited the enhanced expression of IL-8 and COX-2 in PC3 cells in 24 hours. Furthermore, W. somnifera extract (10 μg/mL) irreversibly arrested the cell cycle in G2/M phase, which was evident from the rapid accumulation of PC3 cells significantly.

CONCLUSION

Our results indicate that inherent metastatic and selective inhibitory potential of W. somnifera against PC. W. somnifera may be a good therapeutic agent in addition to the existing drugs for PC. Further studies with more prostate tissue samples are warranted.

Glyoxalase 2 drives tumorigenesis in human prostate cells in a mechanism involving androgen receptor and p53-p21 axis

Glyoxalase 2 (Glo2), a metabolic enzyme, is overexpressed in some human cancers which suggests this enzyme may play a role in human tumorigenesis. In prostate cancer (PCa), the role of Glo2 has been scarcely investigated and there are no studies addressing a causative involvement of this protein in this neoplasia. Here, we examined the immunohistochemical profile of Glo2 in human PCa and benign adjacent tissues and investigated Glo2 involvement in PCa development in human prostate cell lines. PCa and matched adjacent normal tissues were obtained from paraffin sections of primary PCa from 20 patients who had undergone radical prostatectomy. Histopathological diagnosis was confirmed for each sample. Glo2 expression analysis was performed by immunohistochemistry in prostate tissues, and by qRT-PCR and immunoblotting in prostate cell lines. The causative and mechanistic role of Glo2 in prostate tumorigenesis was demonstrated by Glo2 ectopic expression/silencing and employing specific activators/inhibitors. Our results showed that Glo2 was selectively expressed in PCa but not in the luminal compartment of the adjacent benign epithelium consistently in all the examined 20 cases. Glo2 expression in PCa was dependent on androgen receptor (AR) and was aimed at stimulating cell proliferation and eluding apoptosis through a mechanism involving the p53-p21 axis. Glo2 was intensely expressed in the basal cells of benign glands but was not involved in PCa genesis. Our results demonstrate for the first time that Glo2 drives prostate tumorigenesis and suggest that it may represent a novel adjuvant marker in the pathological diagnosis of early PCa.

The TRAIL-Induced Cancer Secretome Promotes a Tumor-Supportive Immune Microenvironment via CCR2

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is known for specifically killing cancer cells, whereas in resistant cancers, TRAIL/TRAIL-R can promote metastasis via Rac1 and PI3K. It remains unknown, however, whether and to what extent TRAIL/TRAIL-R signaling in cancer cells can affect the immune microenvironment. Here we show that TRAIL-triggered cytokine secretion from TRAIL-resistant cancer cells is FADD dependent and identify the TRAIL-induced secretome to drive monocyte polarization to myeloid-derived suppressor cells (MDSCs) and M2-like macrophages. TRAIL-R suppression in tumor cells impaired CCL2 production and diminished both lung MDSC presence and tumor growth. In accordance, the receptor of CCL2, CCR2, is required to facilitate increased MDSC presence and tumor growth. Finally, TRAIL and CCL2 are co-regulated with MDSC/M2 markers in lung adenocarcinoma patients. Collectively, endogenous TRAIL/TRAIL-R-mediated CCL2 secretion promotes accumulation of tumor-supportive immune cells in the cancer microenvironment, thereby revealing a tumor-supportive immune-modulatory role of the TRAIL/TRAIL-R system in cancer biology.

Addressing taxane resistance in metastatic castration-resistant prostate cancer: a focus on chaperone proteins

Despite the significant survival benefit of taxane therapy in metastatic castration-resistant prostate cancer (mCRPC), all patients inevitably develop treatment resistance. An understanding of resistance mechanisms has led to new therapies for prostate cancer (cabazitaxel, abiraterone and enzalutamide), all of which have improved survival following first-line docetaxel. Another treatment, currently in development, targets the prosurvival molecule clusterin. Custirsen, an antisense molecule that inhibits clusterin production, has shown promise in combination with docetaxel in mCRPC patients at risk for poor outcomes. Although optimal sequence and combination of available therapies is unclear, the heterogeneity of mCRPC suggests a continuing need for personalized treatment regimens and improved abilities to predict which patients will respond to the available treatment options.

The CXCL8-CXCR1/2 pathways in cancer

Persistent infection or chronic inflammation contributes significantly to tumourigenesis and tumour progression. C-X-C motif ligand 8 (CXCL8) is a chemokine that acts as an important multifunctional cytokine to modulate tumour proliferation, invasion and migration in an autocrine or paracrine manner. Studies have suggested that CXCL8 and its cognate receptors, C-X-C chemokine receptor 1 (CXCR1) and CX-C chemokine receptor 2 (CXCR2), mediate the initiation and development of various cancers including breast cancer, prostate cancer, lung cancer, colorectal carcinoma and melanoma. CXCL8 also integrates with multiple intracellular signalling pathways to produce coordinated effects. Neovascularisation, which provides a basis for fostering tumour growth and metastasis, is now recognised as a critical function of CXCL8 in the tumour microenvironment. In this review, we summarize the biological functions and ficlinical significance of the CXCL8 signalling axis in cancer. We also propose that CXCL8 may be a potential therapeutic target for cancer treatment

Adaptive pathways and emerging strategies overcoming treatment resistance in castration resistant prostate cancer

The therapies available for prostate cancer patients whom progress from hormone-sensitive to castration resistant prostate cancer include both systemic drugs, including docetaxel and cabazitaxel, and drugs that inhibit androgen signaling such as enzalutamide and abiraterone. Unfortunately, it is estimated that up to 30% of patients have primary resistance to these treatments and over time even those who initially respond to therapy will eventually develop resistance and their disease will continue to progress regardless of the presence of the drug. Determining the mechanisms involved in the development of resistance to these therapies has been the area of intense study and several adaptive pathways have been uncovered. Androgen receptor (AR) mutations, expression of AR-V7 (or other constitutively active androgen receptor variants), intracrine androgen production and overexpression of androgen synthesis enzymes such as Aldo-Keto Reductase Family 1, Member C3 (AKR1C3) are among the many mechanisms associated with resistance to anti-androgens. In regards to the taxanes, one of the key contributors to drug resistance is increased drug efflux through ATP Binding Cassette Subfamily B Member 1 (ABCB1). Targeting these resistance mechanisms using different strategies has led to various levels of success in overcoming resistance to current therapies. For instance, targeting AR-V7 with niclosamide or AKR1C3 with indomethacin can improve enzalutamide and abiraterone treatment. ABCB1 transport activity can be inhibited by the dietary constituent apigenin and antiandrogens such as bicalutamide which in turn improves response to docetaxel. A more thorough understanding of how drug resistance develops will lead to improved treatment strategies. This review will cover the current knowledge of resistance mechanisms to castration resistant prostate cancer therapies and methods that have been identified which may improve treatment response.

Tumor microenvironment B cells increase bladder cancer metastasis via modulation of the IL-8/androgen receptor (AR)/MMPs signals

While B cells in the tumor microenvironment may play important roles in cancer progression, their impacts on the bladder cancer (BCa) metastasis remain unclear. Here we found from human clinical BCa samples that BCa tissues could recruit more B cells than the surrounding normal bladder tissues and the in vitro co-culture assay also demonstrated that B cells could be recruited more easily towards BCa cells compared to normal bladder cells. Chamber invasion and 3D invasion assays showed the recruited B cells could then significantly increase the BCa cell invasion. Mechanism dissection found that recruited B cells could increase IL-8/androgen receptor (AR) signals in BCa cells that could then promote the expression of metastasis genes including MMP1 and MMP13. Blocking the IL-8/AR/MMPs signals either by anti-IL-8 neutralizing antibody, AR-siRNA, or MMPs inhibitors all partially reversed the infiltrating B cells capacity to increase the BCa cell invasion. The in vivo data from orthotopically xenografted BCa mouse model also confirmed that infiltrating B cells could increase BCa cell invasion via increasing AR signals. Together, these results demonstrate the key roles of B cells within the bladder tumor microenvironment that increase the BCa metastasis and may help us to develop the potential therapies via targeting these newly identified IL-8/AR/MMPs signals to better battle the BCa progression.

Inhibition of PI3K/Akt/mTOR signaling in PI3KR2-overexpressing colon cancer stem cells reduces tumor growth due to apoptosis

In sporadic colon cancer, colon cancer stem cells (CCSCs) initiate tumorigenesis and may contribute to late disease recurrences and metastases. We previously showed that aldehyde dehydrogenase (ALDH) activity (as indicated by the ALDEFLUOR^® assay) is an effective marker for highly enriching CCSCs for further evaluation. Here, we used comparative transcriptome and proteome approaches to identify signaling pathways overrepresented in the CCSC population. We found overexpression of several components of the phosphoinositide 3-kinase (PI3K)/Akt/mechanistic target of rapamycin (mTOR) signaling pathway, including PI3KR2, a regulatory subunit of PI3K. LY294002, a PI3K inhibitor, defined the contribution of the PI3K/Akt/mTOR signaling pathway in CCSCs. LY294002-treated CCSCs showed decreases in proliferation, sphere formation and self-renewal, in phosphorylation-dependent activation of Akt, and in expression of cyclin D1. Inhibition of PI3K in vivo reduced tumorigenicity, increased detection of cleaved caspase 3, an indicator of apoptosis, and elevated expression of the inflammatory chemokine, CXCL8. Collectively, these results indicate that PI3K/Akt/mTOR signaling controls CCSC proliferation and CCSC survival, and suggests that it would be useful to develop therapeutic agents that target this signaling pathway.

Thymoquinone inhibits growth of human medulloblastoma cells by inducing oxidative stress and caspase-dependent apoptosis while suppressing NF-κB signaling and IL-8 expression

Medulloblastoma (MB) is the most common malignant brain tumor of childhood. The transcription factor NF-κB is overexpressed in human MB and is a critical factor for MB tumor growth. NF-κB is known to regulate the expression of interleukin-8 (IL-8), the chemokine that enhances cancer cell growth and resistance to chemotherapy. We have recently shown that thymoquinone (TQ) suppresses growth of hepatocellular carcinoma cells in part by inhibiting NF-κB signaling. Here we sought to extend these studies in MB cells and show that TQ suppresses growth of MB cells in a dose- and time-dependent manner, causes G2M cell cycle arrest, and induces apoptosis. TQ significantly increased generation of reactive oxygen species (ROS), while pretreatment of MB cells with the ROS scavenger N-acetylcysteine (NAC) abrogated TQ-induced cell death and apoptosis, suggesting that TQ-induced cell death and apoptosis are oxidative stress-mediated. TQ inhibitory effects were associated with inhibition of NF-κB and altered expression of its downstream effectors IL-8 and its receptors, the anti-apoptotic Bcl-2, Bcl-xL, X-IAP, and FLIP, as well as the pro-apoptotic TRAIL-R1, caspase-8, caspase-9, Bcl-xS, and cytochrome c. TQ-triggered apoptosis was substantiated by up-regulation of the executioner caspase-3 and caspase-7, as well as cleavage of the death substrate poly(ADP-ribose)polymerase. Interestingly, pretreatment of MB cells with NAC or the pan-caspase inhibitor zVAD-fmk abrogated TQ-induced apoptosis, loss of cyclin B1 and NF-κB activity, suggesting that these TQ-mediated effects are oxidative stress- and caspase-dependent. These findings reveal that TQ induces both extrinsic and intrinsic pathways of apoptosis in MB cells, and suggest its potential usefulness in the treatment of MB.

Combination therapy induces unfolded protein response and cytoskeletal rearrangement leading to mitochondrial apoptosis in prostate cancer

Development of therapeutic resistance is responsible for most prostate cancer (PCa) related mortality. Resistance has been attributed to an acquired or selected cancer stem cell phenotype. Here we report the histone deacetylase inhibitor apicidin (APC) or ER stressor thapsigargin (TG) potentiate paclitaxel (TXL)-induced apoptosis in PCa cells and limit accumulation of cancer stem cells. TXL-induced responses were modulated in the presence of TG with increased accumulation of cells at G1-phase, rearrangement of the cytoskeleton, and changes in cytokine release. Cytoskeletal rearrangement was associated with modulation of the cytoplasmic and mitochondrial unfolded protein response leading to mitochondrial dysfunction and release of proapoptotic proteins from mitochondria. TXL in combination with APC or TG enhanced caspase activation. Importantly, TXL in combination with TG induced caspase activation and apoptosis in X-ray resistant LNCaP cells. Increased release of transforming growth factor-beta (TGF-β) was observed while phosphorylated β-catenin level was suppressed with TXL combination treatments. This was accompanied by a decrease in the CD44(+)CD133(+) cancer stem cell-like population, suggesting treatment affects cancer stem cell properties. Taken together, combination treatment with TXL and either APC or TG induces efficient apoptosis in both proliferating and cancer stem cells, suggesting this therapeutic combination may overcome drug resistance and recurrence in PCa.

IL-8 confers resistance to EGFR inhibitors by inducing stem cell properties in lung cancer

Epidermal growth factor receptor (EGFR)-targeted strategy is limited by resistance. We identify the potential genes involved in EGFR TKI (tyrosine kinase inhibitor) resistance and study the therapeutic mechanism in the non-small cell lung cancers. Potential genes involved in resistance were examined by analyzing datasets from a pair of EGFR TKI-sensitive (PC9) and TKI-resistant cells (PC9/gef). Blood specimens from patients taking EGFR TKI as first-line treatment were used to examine the correlation between drug's efficacy and IL-8 level. The effects of IL-8 on gefitinib-induced apoptosis, stemness, and in vivo tumorigenicity were investigated using established cell lines. We identified IL-8 was up-regulated in gefitinib-resistant cells, and high plasma IL-8 level was correlated with shorter progression-free-survival time. IL-8 overexpression suppressed gefitinib-induced apoptosis in gefitinib-sensitive cells. By contrast, suppression of IL-8 enhanced gefitinib-induced cell death in gefitinib-resistant cells. IL-8 also increased stem-like characteristics including aldehyde dehydrogenase activity, expression of stemness-related genes, clonogenic activity, side-population, and in vivo tumorigenicity. Consistently, knockdown of IL-8 leads to loss of stem cell-like characteristics in gefitinib-resistant cells. Our study demonstrates an important role for IL-8, and suggests IL-8 is a potential therapeutic target for overcoming EGFR TKI resistance.

A multi-targeted approach to suppress tumor-promoting inflammation

Cancers harbor significant genetic heterogeneity and patterns of relapse following many therapies are due to evolved resistance to treatment. While efforts have been made to combine targeted therapies, significant levels of toxicity have stymied efforts to effectively treat cancer with multi-drug combinations using currently approved therapeutics. We discuss the relationship between tumor-promoting inflammation and cancer as part of a larger effort to develop a broad-spectrum therapeutic approach aimed at a wide range of targets to address this heterogeneity. Specifically, macrophage migration inhibitory factor, cyclooxygenase-2, transcription factor nuclear factor-κB, tumor necrosis factor alpha, inducible nitric oxide synthase, protein kinase B, and CXC chemokines are reviewed as important antiinflammatory targets while curcumin, resveratrol, epigallocatechin gallate, genistein, lycopene, and anthocyanins are reviewed as low-cost, low toxicity means by which these targets might all be reached simultaneously. Future translational work will need to assess the resulting synergies of rationally designed antiinflammatory mixtures (employing low-toxicity constituents), and then combine this with similar approaches targeting the most important pathways across the range of cancer hallmark phenotypes.

Functional Cross-Talking between Differentially Expressed and Alternatively Spliced Genes in Human Liver Cancer Cells Treated with Berberine

Berberine has been identified with anti-proliferative effects on various cancer cells. Many researchers have been trying to elucidate the anti-cancer mechanisms of berberine based on differentially expressed genes. However, differentially alternative splicing genes induced by berberine might also contribute to its pharmacological actions and have not been reported yet. Moreover, the potential functional cross-talking between the two sets of genes deserves further exploration. In this study, RNA-seq technology was used to detect the differentially expressed genes and differentially alternative spliced genes in BEL-7402 cancer cells induced by berberine. Functional enrichment analysis indicated that these genes were mainly enriched in the p53 and cell cycle signalling pathway. In addition, it was statistically proven that the two sets of genes were locally co-enriched along chromosomes, closely connected to each other based on protein-protein interaction and functionally similar on Gene Ontology tree. These results suggested that the two sets of genes regulated by berberine might be functionally cross-talked and jointly contribute to its cell cycle arresting effect. It has provided new clues for further researches on the pharmacological mechanisms of berberine as well as the other botanical drugs.

Drug resistance in castration resistant prostate cancer: resistance mechanisms and emerging treatment strategies

Several mechanisms facilitate the progression of hormone-sensitive prostate cancer to castration-resistant prostate cancer (CRPC). At present, the approved chemotherapies for CRPC include systemic drugs (docetaxel and cabazitaxel) and agents that target androgen signaling, including enzalutamide and abiraterone. While up to 30% of patients have primary resistance to these treatments, each of these drugs confers a significant survival benefit for many. Over time, however, all patients inevitably develop resistance to treatment and their disease will continue to progress. Several key mechanisms have been identified that give rise to drug resistance. Expression of constitutively active variants of the androgen receptor, such as AR-V7, intracrine androgens and overexpression of androgen synthesis enzymes like AKR1C3, and increased drug efflux through ABCB1 are just some of the many discovered mechanisms of drug resistance. Treatment strategies are being developed to target these pathways and reintroduce drug sensitivity. Niclosamide has been discovered to reduce AR-V7 activity and synergized to enzalutamide. Indomethacin has been explored to inhibit AKR1C3 activity and showed to be able to reverse resistance to enzalutamide. ABCB1 transport activity can be mitigated by the phytochemical apigenin and by antiandrogens such as bicalutamide, with each improving cellular response to chemotherapeutics. By better understanding the mechanisms by which drug resistance develops improved treatment strategies will be made possible. Herein, we review the existing knowledge of CRPC therapies and resistance mechanisms as well as methods that have been identified which may improve drug sensitivity.

Prostate cancer and neuroendocrine differentiation: more neuronal, less endocrine?

Neuroendocrine differentiation (NED) marks a structural and functional feature of certain cancers, including prostate cancer (PCa), whereby the malignant tissue contains a significant proportion of cells displaying neuronal, endocrine, or mixed features. NED cells produce, and can secrete, a cocktail of mediators commonly encountered in the nervous system, which may stimulate and coordinate cancer growth. In PCa, NED appears during advanced stages, subsequent to treatment, and accompanies treatment resistance and poor prognosis. However, the term “neuroendocrine” in this context is intrinsically vague. This article seeks to provide a framework on which a unified view of NED might emerge. First, we review the mutually beneficial interplay between PCa and neural structures, mainly supported by cell biology experiments and neurological conditions. Next, we address the correlations between PCa and neural functions, as described in the literature. Based upon the integration of clinical and basic observations, we suggest that it is legitimate to seek for true neural differentiation, or neuromimicry, in cancer progression, most notably in PCa cells exhibiting what is commonly described as NED.

Novel actions of next-generation taxanes benefit advanced stages of prostate cancer

PURPOSE

To improve the outcomes of patients with castration-resistant prostate cancer (CRPC), there is an urgent need for more effective therapies and approaches that individualize specific treatments for patients with CRPC. These studies compared the novel taxane cabazitaxel with the previous generation docetaxel, and aimed to determine which tumors are most likely to respond.

EXPERIMENTAL DESIGN

Cabazitaxel and docetaxel were compared via in vitro modeling to determine the molecular mechanism, biochemical and cell biologic impact, and cell proliferation, which was further assessed ex vivo in human tumor explants. Isogenic pairs of RB knockdown and control cells were interrogated in vitro and in xenograft tumors for cabazitaxel response.

RESULTS

The data herein show that (i) cabazitaxel exerts stronger cytostatic and cytotoxic response compared with docetaxel, especially in CRPC; (ii) cabazitaxel induces aberrant mitosis, leading to pyknotic and multinucleated cells; (iii) taxanes do not act through the androgen receptor (AR); (iv) gene-expression profiling reveals distinct molecular actions for cabazitaxel; and (v) tumors that have progressed to castration resistance via loss of RB show enhanced sensitivity to cabazitaxel.

CONCLUSIONS

Cabazitaxel not only induces improved cytostatic and cytotoxic effects, but also affects distinct molecular pathways, compared with docetaxel, which could underlie its efficacy after docetaxel treatment has failed in patients with CRPC. Finally, RB is identified as the first potential biomarker that could define the therapeutic response to taxanes in metastatic CRPC. This would suggest that loss of RB function induces sensitization to taxanes, which could benefit up to 50% of CRPC cases.

Chronic inflammatory mediators enhance prostate cancer development and progression

Chronic inflammation is postulated to influence prostate cancer progression. Preclinical studies have claimed that inflammatory mediators are involved in prostate cancer development and therefore suggested these as attractive targets for intervention. However, among the many pro-inflammatory mediators, there is no consensus regarding the identity of the primary one(s). In clinical studies, chronic inflammation has been found in prostate tumor specimens, and tissues resected for treatment of benign prostatic hyperplasia (BPH). Although collective evidence from molecular, experimental and clinical data suggests that inflammation can contribute or promote prostate carcinogenesis, an etiologic link has not yet been established. Moreover, the role of chronic inflammation in the onset of castration resistant and metastatic disease is unclear. Therefore it is important to open a dialog regarding recent findings on how chronic inflammatory mediators contribute to prostate cancer progression, and their usefulness to prevent disease progression. In this commentary, we assess the current literature with respect to chronic inflammation as a potential initiator and promoter of prostate carcinogenesis and discuss the prospects for its potential clinical applications.

Pigment epithelium-derived factor expression prolongs survival and enhances the cytotoxicity of low-dose chemotherapy in castration-refractory prostate cancer

There is currently no cure for advanced castration-refractory prostate cancer (CRPC) despite the recent approval of several new therapeutic agents. We report here the anti-tumor effect of the angio-inhibitory pigment epithelium-derived factor (PEDF) in the metastatic LNCaP-derivative CRPC CL1 model and explore PEDF anti-neoplasic efficacy in combination with low-dose chemotherapy. Androgen-sensitive LNCaP and CRPC PC3 cell lines were examined as comparison. Using a retroviral expression system, we showed that PEDF limited the proliferation of all prostatic cell lines tested; an effect attributed to interleukin 8 (IL8)-CXCR1/IL8RA inhibition. PEDF also reduced the number and size of 3D tumor spheroids in vitro, but only induced cell differentiation in CRPC spheroids. Similarly, PEDF inhibited the migration of CRPC cells suggesting both anti-proliferative and anti-migratory functions. In vivo, PEDF decreased by 85% and 65% the growth of subcutaneous (s.c.) PC3 and CL1 tumors, respectively. In the CL1 orthotopic model, tumor intake with lethal metastases was found in all animals; nevertheless, PEDF prolonged the median survival of tumor-bearing mice (95% confidence interval: 53±0.001 to 57±1 days). Accordingly, PEDF delayed the emergence of skeletal-related event in intra-tibial xenografts. Next, we evaluated low-dose docetaxel (DTX; 5, 1, 0.5 mg/kg) or cyclophosphamide (CTX; 10–20 mg/kg) on established s.c. PC3 tumors that conditionally express PEDF anti-tumoral epitope/NT3. Although NT3–DTX-5 mg/kg combination was inefficient, NT3–DTX-1 mg/kg and -0.5 mg/kg inhibited by 95% and 87.8%, respectively, tumor growth compared with control and induced tumor stasis. Both NT3–CTX combinations were advantageous. Inversely, PEDF–DTX-5 mg/kg and PEDF–CTX-10 mg/kg delayed the most CL1 tumor growth (15, 11 and 5 days for PEDF–DTX-5 mg/kg, PEDF–CTX-10 mg/kg and single treatments, respectively) with elevated apoptosis and serum thrombospondin-1 as possible mechanism and marker, respectively. As well, both PEDF–CTX-10 mg/kg and PEDF–DTX-5 mg/kg prolonged significantly the survival of tumor-bearing mice compared with single treatments. Metastases were reduced in PEDF–DTX-5 mg/kg compared with other treatments, suggesting that PEDF–DTX delayed metastases formation. Our results advocate that PEDF/low-dose chemotherapy may represent a new therapeutic alternative for CRPC.

Redox-mediated and ionizing-radiation-induced inflammatory mediators in prostate cancer development and treatment

SIGNIFICANCE

Radiation therapy is widely used for treatment of prostate cancer. Radiation can directly damage biologically important molecules; however, most effects of radiation-mediated cell killing are derived from the generated free radicals that alter cellular redox status. Multiple proinflammatory mediators can also influence redox status in irradiated cells and the surrounding microenvironment, thereby affecting prostate cancer progression and radiotherapy efficiency.

RECENT ADVANCES

Ionizing radiation (IR)-generated oxidative stress can regulate and be regulated by the production of proinflammatory mediators. Depending on the type and stage of the prostate cancer cells, these proinflammatory mediators may lead to different biological consequences ranging from cell death to development of radioresistance.

CRITICAL ISSUES

Tumors are heterogeneous and dynamic communication occurs between stromal and prostate cancer cells, and complicated redox-regulated mechanisms exist in the tumor microenvironment. Thus, antioxidant and anti-inflammatory strategies should be carefully evaluated for each patient at different stages of the disease to maximize therapeutic benefits while minimizing unintended side effects.

FUTURE DIRECTIONS

Compared with normal cells, tumor cells are usually under higher oxidative stress and secrete more proinflammatory mediators. Thus, redox status is often less adaptive in tumor cells than in their normal counterparts. This difference can be exploited in a search for new cancer therapeutics and treatment regimes that selectively activate cell death pathways in tumor cells with minimal unintended consequences in terms of chemo- and radio-resistance in tumor cells and toxicity in normal tissues.

Use of shRNA for stable suppression of chemokine receptor expression and function in human cancer cell lines

In this chapter, we describe a protocol used for stable silencing of chemokine receptor CXCR7 in human cancer cells using shRNA in a lipid transfection setting, previously published by our laboratory. We provide thorough detail and background information about the process of shRNA to clarify the importance of this process. We use CXCR7 shRNA and scrambled sequence shRNA constructs cloned into a pRS plasmid under the control of a U6 promoter for stable expression. Human cancer cells are transfected with shRNA-pRS using Lipofectamine 2000. Cells stably expressing the shRNA are selected from transfected cultures following 2 weeks in medium containing the selection antibiotic puromycin. The emergent cell colonies are evaluated for knockdown of CXCR7 mRNA and protein expression by q-PCR and immunoblotting with rabbit anti-CXCR7 IgG, respectively.

Role of chemokines in renal cell carcinoma

With new frontiers of pharmaceutical therapies focusing on tumor growth and angiogenesis, understanding the interaction between immune system and tumor microenvironment has become ever more important. Chemokines and chemokine receptors appear to play an integral role in tumor characteristics. Evidence suggests CXCR4, CXCL5, CXCR7, and stromal derived factor-1 appear to be crucial in survival, growth, and metastasis of renal cell carcinoma. As the role of chemokines in renal cancer is becoming more evident, further research will lead to a better understanding of tumor biology and the development of new therapeutic targets to help improve survival.