Progress of molecular targeted therapies for prostate cancers

Therapeutic Opportunities for Biomarkers in Metastatic Spine Tumors

For many spine surgeons, patients with metastatic cancer are often present in an emergent situation with rapidly progressive neurological dysfunction. Since the Patchell trial, scoring systems such as NOMS and SINS have emerged to guide the extent of surgical excision and fusion in the context of chemotherapy and radiation therapy. Yet, while multidisciplinary decision-making is the gold standard of cancer care, in the middle of the night, when a patient needs spinal surgery, the wealth of chemotherapy data, clinical trials, and other medical advances can feel overwhelming. The goal of this review is to provide an overview of the relevant molecular biomarkers and therapies driving patient survival in lung, breast, prostate, and renal cell cancer. We highlight the molecular differences between primary tumors (i.e., the patient's original lung cancer) and the subsequent spinal metastasis. This distinction is crucial, as there are limited data investigating how metastases respond to their primary tumor's targeted molecular therapies. Integrating information from primary and metastatic markers allows for a more comprehensive and personalized approach to cancer treatment.

Potent carotenoid astaxanthin expands the anti-cancer activity of cisplatin in human prostate cancer cells

Prostate cancer (PCa) is the second most common type of cancer and the sixth cause of death in men worldwide. Radiotherapy and immunotherapy are commonly used in treating PCa, but understanding the crosstalk mechanisms of carcinogenesis and new therapeutic approaches is essential for supporting poor diagnosis and existing therapies. Astaxanthin (ASX) is a member of the xanthophyll family that is an oxygenated derivative of carotenoids whose synthesis is in plant extracts from lycopene. ASX has protective effects on various diseases, such as Parkinson's disease and cancer by showing potent antioxidant and anti-inflammatory properties. However, there is an ongoing need for a detailed investigation of the molecular mechanism of action to expand its therapeutic use. In the present study, we showed the new regulatory role of ASX in PCa cells by affecting the unfolded protein response (UPR) signaling, autophagic activity, epithelial-mesenchymal transition (EMT) and regulating the expression level of angiogenesis-related protein vascular endothelial growth factor A (VEGF-A), proto-oncogene c-Myc and prostate-specific antigen (PSA). Additionally, we determined that it exhibited synergistic action with cisplatin and significantly enhanced apoptotic cell death in PCa cells. Present findings suggest that ASX may be a potent adjuvant therapeutic option in PCa treatment when used alone or combined with chemotherapeutics. Schematic illustration of the biochemical activity of astaxanthin and its combination with cisplatin.

Acetylcholine in Carcinogenesis and Targeting Cholinergic Receptors in Oncology

Tumor cells modulate and are modulated by their microenvironments, which include the nervous system. Accumulating evidence links the overexpression and activity of nicotinic and muscarinic cholinergic receptor subtypes to tumorigenesis in breast, ovarian, prostate, gastric, pancreatic, and head and neck cancers. Nicotinic and muscarinic receptors have downstream factors are associated with angiogenesis, cell proliferation and migration, antiapoptotic signaling, and survival. Clinical trials analyzing the efficacy of various therapies targeting cholinergic signaling or downstream pathways of acetylcholine have shed promising light on novel cancer therapeutics. Although the evidence for cholinergic signaling involvement in tumor development is substantial, a more detailed understanding of the acetylcholine-induced mechanisms of tumorigenesis remains to be unlocked. Such an understanding would enable the development of clinical applications ranging from the identification of novel biomarkers to the utilization of existing drugs to modulate cholinergic signaling to the development of novel cancer therapies, as discussed in this review.

HIF-1α and Nrf2 regulates hypoxia induced overexpression of DDAH1 through promoter activation in prostate cancer

Dimethylarginine dimethylaminohydrolase-1 (DDAH1) is overexpressed in prostate cancer (PCa) and promotes PCa progression in in vivo through the ADMA-NO pathway by degrading nitric oxide synthase (NOS) inhibitors such as asymmetric dimethylarginine (ADMA) and monomethylamine arginine (L-NMMA). In this study, we investigated the molecular mechanism involved in the overexpression of DDAH1 in PCa and examined its potential role as a therapeutic target. We observed that DDAH1expression is elevated in PCa (PC3, LNCaP, and DU145) cell lines under hypoxia. ChIP and reporter assay results confirmed that DDAH1 expression is positively regulated by HIF-1α through directly binding to the hypoxia response elements (HRE) located within the promoter region between - 1242/- 1238 upstream of its transcription start site (TSS). Under hypoxia, HIF-1α is translocated into the nucleus and activates its target gene expression in PC3 cells. Interestingly, in the event of HIF-1α inhibition or siRNA-mediated knockdown, an alternative transcription factor Nrf2 promotes DDAH1 expression through antioxidant response elements (AREs) on its promoter. ChIP assay results showed that Nrf2 binds to AREs located between -1016 / -1008 bp from the TSS of DDAH1. Furthermore, knockdown of PCa therapeutic target HSP90, an essential co-factor for both HIF-1α and Nrf2 causes attenuation of hypoxia induced DDAH1 overexpression in PCa cells. These results demonstrate that hypoxia induced upregulation of DDAH1 expression is positively regulated by HIF-1α and Nrf2 in association with HSP90. Therefore, targeting tumor angiogenesis promoting DDAH1 along with standard androgen receptor (AR) targeted therapy may offer an effective strategy to prevent PCa progression.

KRAS, BRAF, PIK3CA mutation frequency of radical prostatectomy samples and review of the literature

OBJECTIVE

The molecular basis of prostate cancer is highly heterogeneous. Our study aimed to perform the mutation analysis of KRAS, BRAF, PIK3CA, and immunohistochemical (IHC) evaluation of EGFR, HER2, p16, and PTEN to demonstrate new areas for targeted therapies.

METHODS

A total of 24 prostatectomy samples diagnosed with adenocarcinoma were analyzed by microarray hybridization. Also, these samples were IHC stained for EGFR, HER2, P16, and PTEN. The cases were divided into two groups based on low and high Gleason scores. All findings were compared with the clinicopathological parameters of the patients.

RESULTS

While KRAS mutation was in 3/24 (12.5%) of our cases, BRAF and PIK3CA mutations were not detected. There was no significant difference between the groups in terms of KRAS mutation frequency. HER2 was immunohistochemically negative in all samples. There was no correlation between EGFR, P16 immunopositivity, and clinicopathological features.

CONCLUSION

KRAS mutation frequency is similar to those in Asian populations. BRAF and PIK3CA mutation frequencies have been reported in the literature in the range of 0-15% and 0-10.4%, respectively, consistent with our study findings. HER2 immunoexpression is a controversial issue in the literature. EGFR and p16 expressions may not correlate with the stage.

Anti-Tumor Effects of Astaxanthin by Inhibition of the Expression of STAT3 in Prostate Cancer

Astaxanthin is a natural product gaining increasing attention due to its safety and anti-cancer properties. In this study, we investigated the mechanisms of the anti-cancer effects of astaxanthin on prostate cancer (PCa) cell lines using aggressive PCa DU145 cells. Also an instantaneous silenced cell line (si-STAT3) derived from DU145 and a control cell line (si-NK) were used for the MTT and colony formation assays to determine the role of astaxanthin in proliferation and colony formation abilities. Flow cytometry assays were used to detect the apoptosis of tumor cells. Migration and invasion assays detected the weakening of the respective abilities. Western blot and RT-PCR tests detected the levels of STAT3 protein and mRNA. Astaxanthin resulted in suppression of the proliferation of DU145 cells and the level of STAT3. The treatment of DU145 cells with astaxanthin decreased the cloning ability, increased the apoptosis percentage and weakened the abilities of migration and invasion of the cells. Furthermore, astaxanthin reduced the expression of STAT3 at protein and mRNA levels. The effects were enhanced when astaxanthin and si-STAT3 were combined. The results of animal experiments were consistent with the results in cells. Thus, astaxanthin inhibits the proliferation of DU145 cells by reducing the expression of STAT3.

Dehydrozingerone, a Curcumin Analog, as a Potential Anti-Prostate Cancer Inhibitor In Vitro and In Vivo

Curcumin (Cur) exhibits biological activities that support its candidacy for cancer treatment. However, there are limitations to its pharmacological effects, such as poor solubility and bioavailability. Notably, the use of Cur analogs has potential for addressing these limitations. Dehydrozingerone (DZG) is a representative of the half-chemical structure of Cur, and many reports have indicated that it is anticancer in vitro. We, therefore, have hypothesized that DZG could inhibit prostate cancer progression both in vitro and in vivo. Results revealed that DZG decreased cell proliferation of rat castration-resistant prostate cancer, PLS10 cells, via induction of the cell cycle arrest in the G1 phase in vitro. In the PLS10 xenograft model, DZG significantly decreased the growth of subcutaneous tumors when compared to the control via the inhibition of cell proliferation and angiogenesis. To prove that DZG could improve the limitations of Cur, an in vivo pharmacokinetic was determined. DZG was detected in the serum at higher concentrations and remained up to 3 h after intraperitoneal injections, which was longer than Cur. DZG also showed superior in vivo tissue distribution than Cur. The results suggest that DZG could be a candidate of the Cur analog that can potentially exert anticancer capabilities in vivo and thereby improve its bioavailability.

Co-Delivery of Natural Compounds with a Dual-Targeted Nanoparticle Delivery System for Improving Synergistic Therapy in an Orthotopic Tumor Model

Various natural compounds including epigallocatechin gallate (EGCG) and curcumin (CU) have potential in developing anticancer therapy. However, their clinical use is commonly limited by instability and low tissue distribution. EGCG and CU combined treatment can improve the efficacy with synergistic effects. To improve the synergistic effect and overcome the limitations of low tissue distribution, we applied a dual cancer-targeted nanoparticle system to co-deliver EGCG and CU. Nanoparticles were composed of hyaluronic acid, fucoidan, and poly(ethylene glycol)-gelatin to encapsulate EGCG and CU. Furthermore, a dual targeting system was established with hyaluronic acid and fucoidan, which were used as agents for targeting CD44 on prostate cancer cells and P-selectin in tumor vasculature, respectively. Their effect and efficacy were investigated in prostate cancer cells and a orthotopic prostate tumor model. The EGCG/CU-loaded nanoparticles bound to prostate cancer cells, which were uptaken more into cells, leading to a better anticancer efficiency compared to the EGCG/CU combination solution. In addition, the releases of EGCG and CU were regulated by their pH value that avoided the premature release. In mice, treatment of the cancer-targeted EGCG/CU-loaded nanoparticles significantly attenuated the orthotopic tumor growth without inducing organ injuries. Overall, the dual-targeted nanoparticle system for the co-delivery of EGCG and CU greatly improved its synergistic effect in cancer therapy, indicating its great potential in developing treatments for prostate cancer therapy.

MicroRNAs in prostate cancer: From function to biomarker discovery

MicroRNAs (miRNAs) are a small functional non-coding RNAs that post-transcriptionally regulate gene expression through mRNA degradation or translational repression. miRNAs are key regulatory components of various cellular networks. Current evidence support that multiple mammalian genome-encoded miRNAs impact the cellular biology, including proliferation, apoptosis, differentiation, and tumorigenesis, by targeting specific subsets of mRNAs. This minireview is focused on the current themes underlying the interactions between miRNAs and their mRNA targets and pathways in prostate tumorigenesis and progression, and their potential clinical utility as biomarkers for prostate cancer. Impact statement The primary goal of this article was to review recent literature on miRNA biogenesis and further elaborate on the identity of newly discovered miRNAs and their potential functional significance in the complex biological network associated with prostate tumorigenesis and disease progression and as biomarkers for prostate cancer.

Elevated Serum Sialic Acid Levels Predict Prostate Cancer As Well As Bone Metastases

Objective: To evaluate the value of serum sialic acid (SA) in diagnosis of benign prostatic hyperplasia (BPH), prostate cancer (PCa), and bone metastases in PCa patients. Materials and Methods: Data from 540 patients who were newly diagnosed with PCa or BPH between November 2014 and March 2018 were retrospectively collected and analyzed. Pretreatment SA levels were compared across various groups, then, associations between SA levels and clinic parameters of patients were analyzed as well. Univariate and multivariate logistic regression analyses were further used to identify independent associations. Results: The mean SA levels in patients with PCa were significantly higher than with BPH (p = 0.013). Furthermore, PCa patients with bone metastases showed elevated SA levels compared with PCa without bone metastases (p < 0.001). A multivariate logistic regression model showed that: SA level > 52.35 mg/dL was identified to be independently associated with the diagnosis of PCa (HR = 1.645, p = 0.036), and SA level > 59 mg/dL was identified to be independent association with the presence of bone metastases in PCa patients (HR = 6.421, p = 0.012). Conclusions: Elevated SA level is an independent predictor of prostate cancer as well as its bone metastases. Therefore, SA level may be a promising diagnostic and prognostic biomarker for prostate cancer and bone metastases.

Cyclohexanone curcumin analogs inhibit the progression of castration-resistant prostate cancer in vitro and in vivo

Many prostate cancer patients develop resistance to treatment called castration‐resistant prostate cancer (CRPC) which is the major cause of recurrence and death. In the present study, four cyclohexanone curcumin analogs were synthesized. Additionally, their anticancer progression activity on CRPC cell lines, PC3 and PLS10 cells, was examined. We first determined their anti‐metastasis properties and found that 2,6‐bis‐(4‐hydroxy‐3‐methoxy‐benzylidene)‐cyclohexanone (2A) and 2,6‐bis‐(3,4‐dihydroxy‐benzylidene)‐cyclohexanone (2F) showed higher anti‐invasion properties against CRPC cells than curcumin. Analog 2A inhibited both MMP‐2 and MMP‐9 secretions and activities, whereas analog 2F reduced only MMP activities. These findings suggest that the compounds may inhibit CRPC cell metastasis by decreased extracellular matrix degradation. Analog 2A, the most potent analog, was then subjected to an in vivo study. Similar to curcumin, analog 2A was detectable in the serum of mice at 30 and 60 minutes after i.p. injections. Analog 2A and curcumin (30 mg/kg bodyweight) showed a similar ability to reduce tumor area in lungs of mice that were i.v. injected with PLS10 cells. Additionally, analog 2A showed superior growth inhibitory effect on PLS10 cells than that of curcumin both in vitro and in vivo. The compound inhibited PLS10 cells growth by induction of G1 phase arrest and apoptosis in vitro. Interestingly, analog 2A significantly decreased tumor growth with downregulation of cell proliferation and angiogenesis in PLS10‐bearing mice. Taken together, we could summarize that analog 2A showed promising activities in inhibiting CRPC progression both in vitro and in vivo.

Biomarker microRNAs for prostate cancer metastasis: screened with a network vulnerability analysis model

Background

Prostate cancer (PCa) is a fatal malignant tumor among males in the world and the metastasis is a leading cause for PCa death. Biomarkers are therefore urgently needed to detect PCa metastatic signature at the early time. MicroRNAs are small non-coding RNAs with the potential to be biomarkers for disease prediction. In addition, computer-aided biomarker discovery is now becoming an attractive paradigm for precision diagnosis and prognosis of complex diseases.

Methods

In this study, we identified key microRNAs as biomarkers for predicting PCa metastasis based on network vulnerability analysis. We first extracted microRNAs and mRNAs that were differentially expressed between primary PCa and metastatic PCa (MPCa) samples. Then we constructed the MPCa-specific microRNA-mRNA network and screened microRNA biomarkers by a novel bioinformatics model. The model emphasized the characterization of systems stability changes and the network vulnerability with three measurements, i.e. the structurally single-line regulation, the functional importance of microRNA targets and the percentage of transcription factor genes in microRNA unique targets.

Results

With this model, we identified five microRNAs as putative biomarkers for PCa metastasis. Among them, miR-101-3p and miR-145-5p have been previously reported as biomarkers for PCa metastasis and the remaining three, i.e. miR-204-5p, miR-198 and miR-152, were screened as novel biomarkers for PCa metastasis. The results were further confirmed by the assessment of their predictive power and biological function analysis.

Conclusions

Five microRNAs were identified as candidate biomarkers for predicting PCa metastasis based on our network vulnerability analysis model. The prediction performance, literature exploration and functional enrichment analysis convinced our findings. This novel bioinformatics model could be applied to biomarker discovery for other complex diseases.

Electronic supplementary material

The online version of this article (10.1186/s12967-018-1506-7) contains supplementary material, which is available to authorized users.

Drug Repositioning for Effective Prostate Cancer Treatment

Drug repositioning has gained attention from both academia and pharmaceutical companies as an auxiliary process to conventional drug discovery. Chemotherapeutic agents have notorious adverse effects that drastically reduce the life quality of cancer patients so drug repositioning is a promising strategy to identify non-cancer drugs which have anti-cancer activity as well as tolerable adverse effects for human health. There are various strategies for discovery and validation of repurposed drugs. In this review, 25 repurposed drug candidates are presented as result of different strategies, 15 of which are already under clinical investigation for treatment of prostate cancer (PCa). To date, zoledronic acid is the only repurposed, clinically used, and approved non-cancer drug for PCa. Anti-cancer activities of existing drugs presented in this review cover diverse and also known mechanisms such as inhibition of mTOR and VEGFR2 signaling, inhibition of PI3K/Akt signaling, COX and selective COX-2 inhibition, NF-κB inhibition, Wnt/β-Catenin pathway inhibition, DNMT1 inhibition, and GSK-3β inhibition. In addition to monotherapy option, combination therapy with current anti-cancer drugs may also increase drug efficacy and reduce adverse effects. Thus, drug repositioning may become a key approach for drug discovery in terms of time- and cost-efficiency comparing to conventional drug discovery and development process.

Raman spectroscopy for accurately characterizing biomolecular changes in androgen-independent prostate cancer cells

Metastatic prostate cancer resistant to hormonal manipulation is considered the advanced stage of the disease and leads to most cancer-related mortality. With new research focusing on modulating cancer growth, it is essential to understand the biochemical changes in cells that can then be exploited for drug discovery and for improving responsiveness to treatment. Raman spectroscopy has a high chemical specificity and can be used to detect and quantify molecular changes at the cellular level. Collection of large data sets generated from biological samples can be employed to form discriminatory algorithms for detection of subtle and early changes in cancer cells. The present study describes Raman finger printing of normal and metastatic hormone-resistant prostate cancer cells including analyses with principal component analysis and linear discrimination. Amino acid-specific signals were identified, especially loss of arginine band. Androgen-resistant prostate cancer cells presented a higher content of phenylalanine, tyrosine, DNA and Amide III in comparison to PNT2 cells, which possessed greater amounts of L-arginine and had a B conformation of DNA. The analysis utilized in this study could reliably differentiate the 2 cell lines (sensitivity 95%; specificity 88%).

Radiosensitization by the investigational NEDD8-activating enzyme inhibitor MLN4924 (pevonedistat) in hormone-resistant prostate cancer cells

Salvage radiotherapy (SRT) is the first-line treatment for prostate cancer patients with biochemical recurrence following radical prostatectomy, and new specific radiosensitizers are in urgent need to enhance SRT effect. MLN4924 (also known as Pevonedistat), a specific inhibitor of NEDD8-activating enzyme, has recently entered phase I/II clinical trials in several malignancies. By inhibiting cullin neddylation, MLN4924 inactivates Cullin-RING ligases (CRL), which have been validated as an attractive radiosensitizing target. In our study, we demonstrate that MLN4924 can be used as a potent radiosensitizer in hormone-resistant prostate cancer cells. We found that MLN4924 inhibited cullin neddylation and sensitized prostate cancer cells to irradiation (IR). Mechanistically, MLN4924 enhanced IR-induced G2 cell-cycle arrest, by inducing accumulation of WEE1/p21/p27, three well-known CRL substrates. Importantly, siRNA knockdown of WEE1/p21/p27 partially abrogated MLN4924-induced G2 cell-cycle arrest, indicating a causal role of WEE1/p21/p27 in MLN4924-induced radiosensitization. Further mechanistic studies revealed that induction of DNA damage and apoptosis also contributed to MLN4924 radiosensitization in hormone-resistant prostate cancer cells. Our findings lay the foundation for future application of MLN4924 as a potential radiosensitizer in hormone refractory prostate cancer (HRPC).

PSMA-targeted polyinosine/polycytosine vector induces prostate tumor regression and invokes an antitumor immune response in mice

There is an urgent need for an effective treatment for metastatic prostate cancer (PC). Prostate tumors invariably overexpress prostate surface membrane antigen (PSMA). We designed a nonviral vector, PEI-PEG-DUPA (PPD), comprising polyethylenimine-polyethyleneglycol (PEI-PEG) tethered to the PSMA ligand, 2-[3-(1, 3-dicarboxy propyl)ureido] pentanedioic acid (DUPA), to treat PC. The purpose of PEI is to bind polyinosinic/polycytosinic acid (polyIC) and allow endosomal release, while DUPA targets PC cells. PolyIC activates multiple pathways that lead to tumor cell death and to the activation of bystander effects that harness the immune system against the tumor, attacking nontargeted neighboring tumor cells and reducing the probability of acquired resistance and disease recurrence. Targeting polyIC directly to tumor cells avoids the toxicity associated with systemic delivery. PPD selectively delivered polyIC into PSMA-overexpressing PC cells, inducing apoptosis, cytokine secretion, and the recruitment of human peripheral blood mononuclear cells (PBMCs). PSMA-overexpressing tumors in nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mice with partially reconstituted immune systems were significantly shrunken following PPD/polyIC treatment, in all cases. Half of the tumors showed complete regression. PPD/polyIC invokes antitumor immunity, but unlike many immunotherapies does not need to be personalized for each patient. The potent antitumor effects of PPD/polyIC should spur its development for clinical use.

Manumycin A suppresses exosome biogenesis and secretion via targeted inhibition of Ras/Raf/ERK1/2 signaling and hnRNP H1 in castration-resistant prostate cancer cells

Emerging evidence links exosomes to cancer progression by the trafficking of oncogenic factors and neoplastic reprogramming of stem cells. This necessitates identification and integration of functionally validated exosome-targeting therapeutics into current cancer management regimens. We employed quantitative high throughput screen on two libraries to identify exosome-targeting drugs; a commercially available collection of 1280 pharmacologically active compounds and a collection of 3300 clinically approved compounds. Manumycin-A (MA), a natural microbial metabolite, was identified as an inhibitor of exosome biogenesis and secretion by castration-resistant prostate cancer (CRPC) C4-2B, but not the normal RWPE-1, cells. While no effect was observed on cell growth, MA attenuated ESCRT-0 proteins Hrs, ALIX and Rab27a and exosome biogenesis and secretion by CRPC cells. The MA inhibitory effect is primarily mediated via targeted inhibition of the Ras/Raf/ERK1/2 signaling. The Ras-dependent MA suppression of exosome biogenesis and secretion is partly mediated by ERK-dependent inhibition of the oncogenic splicing factor hnRNP H1. Our findings suggest that MA is a potential drug candidate to suppress exosome biogenesis and secretion by CRPC cells.

REST is a crucial regulator for acquiring EMT-like and stemness phenotypes in hormone-refractory prostate cancer

Castration-resistance prostate cancer (CRPC), also known as hormone-refractory prostate cancer (HRPC), requires immediate attention since it is not only resistant to androgen ablation, chemo- and radiotherapy, but also highly metastatic. Increasing evidence suggests that enrichment of neuroendocrine (NE) cells is associated with CRPC. Here, combined RNA-seq and ChIP-seq analysis reveals that REST is involved in epithelial-mesenchymal transition (EMT) and stemness acquisition in NE differentiated prostate cancer (PCa) cells via direct transcriptional repression of Twist1 and CD44. Specifically we show that short-term knockdown of REST induces NE differentiation of LNCaP cells. Long-term REST knockdown enhanced the expression of Twist1 and CD44, cell migration and sphere formation. Overexpression of REST in hormone-refractory CWR22Rv1 PCa cells significantly reduces Twist1 and CD44 expression, cell migration and sphere formation. Collectively, our study uncovers REST in regulating EMT and stemness properties of NE PCa cells and suggests that REST is a potential therapeutic target for CRPC.

Tie-2 regulates the stemness and metastatic properties of prostate cancer cells

Ample evidence supports that prostate tumor metastasis originates from a rare population of cancer cells, known as cancer stem cells (CSCs). Unfortunately, little is known about the identity of these cells, making it difficult to target the metastatic prostate tumor. Here, for the first time, we report the identification of a rare population of prostate cancer cells that express the Tie-2 protein. We found that this Tie-2High population exists mainly in prostate cancer cell lines that are capable of metastasizing to the bone. These cells not only express a higher level of CSC markers but also demonstrate enhanced resistance to the chemotherapeutic drug Cabazitaxel. In addition, knockdown of the expression of the Tie-2 ligand angiopoietin (Ang-1) led to suppression of CSC markers, suggesting that the Ang-1/Tie-2 signaling pathway functions as an autocrine loop for the maintenance of prostate CSCs. More importantly, we found that Tie-2High prostate cancer cells are more adhesive than the Tie-2Low population to both osteoblasts and endothelial cells. Moreover, only the Tie-2High, but not the Tie-2Low cells developed tumor metastasis in vivo when injected at a low number. Taken together, our data suggest that Tie-2 may play an important role during the development of prostate tumor metastasis.

Recent developments in receptor tyrosine kinases targeted anticancer therapy

Novel concepts and understanding of receptors lead to discoveries and optimization of many small molecules and antibodies as anti-cancerous drugs. Receptor tyrosine kinases (RTKs) are such a promising class of receptors under the investigation in past three decades. RTKs are one of the essential mediators of cell signaling mechanism for various cellular processes. Transformations such as overexpression, dysregulation, or mutations of RTKs may result into malignancy, and thus are an important target for anticancer therapy. Numerous subfamilies of RTKs, such as epidermal growth factor receptor, vascular endothelial growth factor receptor, fibroblast growth factor receptors, insulin-like growth factor receptor, and hepatocyte growth factor receptor, have been being investigated in recent years as target for anticancer therapy. The present review focuses several small molecules drugs as well as monoclonal antibodies targeting aforesaid subfamilies either approved or under investigation to treat the various cancers.

Ovarian cancer transformation from adenocarcinoma to undifferentiated small cell carcinoma: A case report

The ovaries contain cells that have the capacity for regeneration and cancer stem cells (CSC) that are capable of differentiating aberrantly from the homeostatic controls. The histology of ovarian cancer does not usually change in a patient. However, CSCs are the origin of a number of tumors. CSCs are known to exist in ovarian carcinomas and the expression of CD44, c-Kit and CD133 has been identified in such carcinomas. This study presents the case of a patient diagnosed with ovarian cancer with an abdominal mass who underwent surgery, eight cycles of gemcitabine-paclitaxel chemotherapy and irradiation. Pathological examination indicated a transformation from adenocarcinoma to undifferentiated small cell carcinoma. The expression of CD133 changed from negative to positive in ovarian carcinomas. The present case indicates that any histological changes observed in ovarian neoplasms originate from neoplastic stem cells. In addition, this case demonstrates the importance of repeatedly assessing therapy by tumor biopsy throughout the course of ovarian cancer treatment.

Gonadotropin-releasing hormone agonists sensitize, and resensitize, prostate cancer cells to docetaxel in a p53-dependent manner

Gonadotropin-releasing hormone (GnRH) receptors are expressed in prostate cancer, specifically in the most aggressive stage of the tumor (castration-resistant prostate cancer, CRPC) for which the standard treatment, docetaxel-based chemotherapy, can only improve the median survival time by few months. We previously showed that GnRH agonists exert an antitumor activity in CRPC cells; however, a link between GnRH receptors and the apoptotic machinery remains to be defined. Aim of this study was to evaluate whether, in CRPC cells, GnRH agonists might affect the expression/activity of apoptosis-related proteins and might sensitize, or resensitize, cancer cells to chemotherapeutics. We demonstrated that, in p53-positive DU145 cells, GnRH agonists: a) increase the expression of the proapoptotic protein Bax; this effect is mediated by the phosphorylation (activation) of p53, triggered by the p38 MAPK; b) potentiate the antiproliferative/proapoptotic activity of docetaxel; c) resensitize docetaxel-resistant cells to the antitumor activity of the cytotoxic drug. These data indicate that GnRH agonists sensitize and, more importantly, resensitize DU145 CRPC cells to chemotherapy in a p53-dependent manner. To confirm the crucial role of p53 in the activity of GnRH agonists, experiments were performed in p53-null PC3 cells. We found that GnRH agonists fail to increase Bax expression and do not potentiate the cytotoxic activity of docetaxel. These results may provide a rationale for novel combination treatment strategies, especially for docetaxel-resistant CRPC patients expressing a functional p53 protein.

The osteoblastic and osteoclastic interactions in spinal metastases secondary to prostate cancer

Prostate cancer (PC) is one of the most common cancers arising in men and has a high propensity for bone metastasis, particularly to the spine. At this stage, it often causes severe morbidity due to pathological fracture and/or metastatic epidural spinal cord compression which, if untreated, inevitably leads to intractable pain, neurological deficit, and paralysis. Unfortunately, the underlying molecular mechanisms driving growth of secondary PC in the bony vertebral column remain largely unknown. Further investigation is warranted in order to identify therapeutic targets in the future. This review summarizes the current understanding of PC bone metastasis in the spine, highlighting interactions between key tumor and bone-derived factors which influence tumor progression, especially the functional roles of osteoblasts and osteoclasts in the bone microenvironment through their interactions with metastatic PC cells and the critical pathway RANK/RANKL/OPG in bone destruction.