Prostate cancer solitary metastasis to anal canal: case report and review of literature.

BACKGROUND: Here we present the first cases of prostate cancer solitary metastasis to anal canal. CASE PRESENTATION: A 67-year-old male patient underwent radical prostatectomy with ilio-obturator lymphonodectomy in 2016 due to poorly differentiated ductal adenocarcinoma (Gleason 4 + 5(40%) = 9) pT3bN0. Two months later increasing PSA rate was noted and the patient started adjuvant intermittent androgen deprivation therapy combined with radiotherapy. Year after patient was admitted to the hospital complaining of dyschezia, pain in anal canal, and bloody stool. Digital rectal examination revealed an anal fissure with ulceration. A biopsy from ulcerated area showed poorly differentiated ductal adenocarcinoma of the prostate. Because there was no evidence of distant metastases on abdominal computed tomography (CT) scan and pelvic magnetic nuclear resonance imaging (MRI) and the only metastasis was in anal canal patient underwent laparoscopic abdominoperineal resection (APR). Postoperative course was uneventful and patient was discharged at postoperative day 7. CONCLUSIONS: Our presented case is the first to describe prostate cancer solitary metastasis to anal canal and we always have to be aware of possible rare disease while assessing the patient with rectal bleeding. Biopsy most of the time is the only and the most reliable test to differentiate between the diseases.

Expression of E-cadherin and specific CXCR3 isoforms impact each other in prostate cancer.

BACKGROUND: Carcinoma cells shift between epithelial and mesenchymal phenotypes during cancer progression, as defined by surface presentation of the cell-cell cohesion molecule E-cadherin, affecting dissemination, progression and therapy responsiveness. Concomitant with the loss of E-cadherin during the mesenchymal transition, the predominant receptor isoform for ELR-negative CXC ligands shifts from CXCR3-B to CXCR3-A which turns this classical G-protein coupled receptor from an inhibitor to an activator of cell migration, thus promoting tumor cell invasiveness. We proposed that CXCR3 was not just a coordinately changed receptor but actually a regulator of the cell phenotype. METHODS: Immunoblotting, immunofluorescence, quantitative real-time PCR and flow cytometry assays investigated the expression of E-cadherin and CXCR3 isoforms. Intrasplenic inoculation of human prostate cancer (PCa) cells with spontaneous metastasis to the liver analyzed E-cadherin and CXCR3-B expression during cancer progression in vivo. RESULTS: We found reciprocal regulation of E-cadherin and CXCR3 isoforms. E-cadherin surface expression promoted CXCR3-B presentation on the cell membrane, and to a lesser extent increased its mRNA and total protein levels. In turn, forced expression of CXCR3-A reduced E-cadherin expression level, whereas CXCR3-B increased E-cadherin in PCa. Meanwhile, a positive correlation of E-cadherin and CXCR3-B expression was found both in experimental PCa liver micro-metastases and patients' tissue. CONCLUSIONS: CXCR3-B and E-cadherin positively correlated in vitro and in vivo in PCa cells and liver metastases, whereas CXCR3-A negatively regulated E-cadherin expression. These results suggest that CXCR3 isoforms may play important roles in cancer progression and dissemination via diametrically regulating tumor's phenotype.

SIRT3 inhibits prostate cancer metastasis through regulation of FOXO3A by suppressing Wnt/ß-catenin pathway.

SIRT3, a mitochondrial NAD+-dependent deacetylase, has been reported to restrain prostate cancer growth both in vitro and in vivo, however, its role in metastatic prostate cancer has not been revealed. In this study, we reported that SIRT3 inhibited the epithelial-mesenchymal transition (EMT) and migration of prostatic cancer cells in vitro and their metastasis in vivo. Consistently, based on analyses of tissue microarray and microarray datasets, lower SIRT3 expression level was correlated with higher prostate cancer Gleason scores, and SIRT3 expression were significantly decreased in metastatic tissues compared with prostate tumor tissues. Mechanistically, SIRT3 promoted FOXO3A expression by attenuating Wnt/ß-catenin pathway, thereby inhibiting EMT and migration of prostate cancer cells. Indeed, SIRT3's inhibitory effect on EMT and migration of prostate cancer cells can be rescued after applying Wnt/ß-catenin pathway activator LiCl, or boosted by wnt inhibitor XAV939. Together, this study revealed a novel mechanism for prostate cancer metastasis that involves SIRT3/ Wnt/ß-catenin/ FOXO3A signaling to modulate EMT and cell migration.

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.

Formulation and Evaluation of Anisamide-Targeted Amphiphilic Cyclodextrin Nanoparticles To Promote Therapeutic Gene Silencing in a 3D Prostate Cancer Bone Metastases Model.

In recent years, RNA interference (RNAi) has emerged as a potential therapeutic offering the opportunity to treat a wide range of diseases, including prostate cancer. Modified cyclodextrins have emerged as effective gene delivery vectors in a range of disease models. The main objective of the current study was to formulate anisamide-targeted cyclodextrin nanoparticles to interact with the sigma receptor (overexpressed on the surface of prostate cancer cells). The inclusion of octaarginine in the nanoparticle optimized uptake and endosomal release of siRNA in two different prostate cancer cell lines (PC3 and DU145 cells). Resulting nanoparticles were less than 200 nm in size with a cationic surface charge (∼+20 mV). In sigma receptor-positive cell lines, the uptake of anisamide-targeted nanoparticles was reduced in the presence of the sigma receptor competitive ligand, haloperidol. When cells were transfected in 2D, the levels of PLK1 mRNA knockdown elicited by targeted versus untargeted nanoparticles tended to be greater but the differences were not statistically different. In contrast, when cells were grown on 3D scaffolds, recapitulating bone metastasis, targeted formulations showed significantly higher levels of PLK1 mRNA knockdown (46% for PC3 and 37% for DU145, p < 0.05). To our knowledge, this is the first time that a targeted cyclodextrin has been used to transfect prostate cancer cells in a 3D model of bone metastasis.

IL-17 and insulin/IGF1 enhance adhesion of prostate cancer cells to vascular endothelial cells through CD44-VCAM-1 interaction.

BACKGROUND: Extravasation is a critical step in cancer metastasis, in which adhesion of intravascular cancer cells to the vascular endothelial cells is controlled by cell surface adhesion molecules. The role of interleukin-17 (IL-17), insulin, and insulin-like growth factor 1 (IGF1) in adhesion of prostate cancer cells to the vascular endothelial cells is unknown, which is the subject of the present study. METHODS: Human umbilical vein endothelial cells (HUVECs) and human prostate cancer cell lines (PC-3, DU-145, LNCaP, and C4-2B) were analyzed for expression of vascular cell adhesion molecule 1 (VCAM-1), integrins, and cluster of differentiation 44 (CD44) using flow cytometry and Western blot analysis. The effects of IL-17, insulin, and IGF1 on VCAM-1 expression and adhesion of prostate cancer cells to HUVECs were examined. The interaction of VCAM-1 and CD44 was assessed using immunoprecipitation assays. RESULTS: Insulin and IGF1 acted with IL-17 to increase VCAM-1 expression in HUVECs. PC-3, DU-145, LNCaP, and C4-2B cells expressed ß1 integrin but not α4 integrin. CD44 was expressed by PC-3 and DU-145 cells but not by LNCaP or C4-2B cells. When HUVECs were treated with IL-17, insulin or IGF1, particularly with a combination of IL-17 and insulin (or IGF1), adhesion of PC-3 and DU-145 cells to HUVECs was significantly increased. In contrast, adhesion of LNCaP and C4-2B cells to HUVECs was not affected by treatment of HUVECs with IL-17 and/or insulin/IGF1. CD44 expressed in PC-3 cells physically bound to VCAM-1 expressed in HUVECs. CONCLUSIONS: CD44-VCAM-1 interaction mediates the adhesion between prostate cancer cells and HUVECs. IL-17 and insulin/IGF1 enhance adhesion of prostate cancer cells to vascular endothelial cells through increasing VCAM-1 expression in the vascular endothelial cells. These findings suggest that IL-17 may act with insulin/IGF1 to promote prostate cancer metastasis.

Leptomeningeal metastases in prostate cancer: A review of the current literature.

Leptomeningeal metastasis/leptomeningeal carcinomatosis (LMC; terms used interchangeably) is an inflammatory complication of primary tumors that involves the spread of the disease to the meninges (specifically the arachnoid and pia maters) and spinal cord. In the United States, approximately 110,000 new cases are diagnosed each year, and the prognosis is usually poor. Complications of LMC include cognitive impairment, cranial nerve dysfunction, ischemic stroke, and mortality. The survival times of untreated and treated LMC are approximately 4-6 weeks and 2-4 months, respectively. Leptomeningeal carcinomatoses are usually metastatic cancers that spread to the central nervous system. Although lung and breast cancers have a clearly defined relationship with LMC, it remains unclear whether prostate cancer (PC) is also directly associated with LMC. To determine whether such association exists, we conducted a PubMed review of the literature on patients with PC with coexisting LMCs. Our search yielded 23 case reports of patients with preexisting PC who developed LMC. In addition, 2 retrospective cohort studies were examined. Various findings were identified in the revised cases and studies. The first 3 findings were related to the progression of the disease: patients presenting with neurological disease symptoms were in remission from PC for 7 years on average, LMCs tended to occur after other cancer diagnoses, and the disease had already rapidly progressed by the time the symptoms were present. Regarding diagnosis, the major finding was that most LMCs were detected by magnetic resonance imaging (which does not detect early dissemination), and it was suggested that single-photon emission computed tomography or positron emission tomography imaging could be used for earlier detection. Finally, in terms of treatment, the main finding was that treatment was palliative rather than curative and that prognosis remained poor despite treatment. On the basis of these results, we recommend for individuals with risk factors, such as high-grade PC and hormonal PC, to be evaluated on a case-by-case basis for increased surveillance of LMC development.

The miRNAs 203a/210-3p/5001-5p regulate the androgen/androgen receptor/YAP-induced migration in prostate cancer cells.

BACKGROUND: Prostate cancer (PCa) patients with elevated level of androgen receptor (AR) correlate with higher metastatic incidence. Protein expression of AR and its target gene prostate-specific antigen (PSA) are elevated in metastatic prostate tumors as compared to organ-confined tumors. Androgen treatment or elevation of AR promotes metastasis of PCa in cell culture and murine model. However, under androgen depleted condition, AR suppressed cell mobility and invasiveness of PCa cells. Androgen deprivation therapy in PCa patients is associated with higher risk of cancer metastasis. We therefore investigated the dual roles of AR and miRNAs on PCa metastasis. METHODS: The PC-3AR (PC-3 cells re-expressing AR) and LNCaP cells were used as PCa cell model. Transwell migration and invasion assay, wound-healing assay, zebrafish xenotransplantation assay, and zebrafish vascular exit assay were used to investigate the role of AR and androgen on PCa metastasis. Micro-Western Array, co-immunoprecipitation and Immunofluorescence were applied to dissect the molecular mechanism lying underneath. The miRNA array, miRNA inhibitors or plasmid, and chromatin immunoprecipitation assay were used to study the role of miRNAs on PCa metastasis. RESULTS: In the absence of androgen, AR repressed the migration and invasion of PCa cells. When androgen was present, AR stimulated the migration and invasion of PCa cells both in vitro and in zebrafish xenotransplantation model. Androgen increased phospho-AR Ser81 and yes-associated protein 1 (YAP), decreased phospho-YAP Ser217, and altered epithelial-mesenchymal transition (EMT) proteins in PCa cells. Co-IP assay demonstrated that androgen augmented the interaction between YAP and AR in nucleus. Knockdown of YAP or treatment with YAP inhibitor abolished the androgen-induced migration and invasion of PCa cells, while overexpression of YAP showed opposite effects. The miRNA array revealed that androgen decreased hsa-miR-5001-5p but increased hsa-miR-203a and hsa-miR-210-3p in PC-3AR cells but not PC-3 cells. Treatment with inhibitors targeting hsa-miR-203a/hsa-miR-210-3p, or overexpression of hsa-miR-5001-5p decreased YAP expression as well as suppressed the androgen-induced migration and invasion of PCa cells. Chromatin immunoprecipitation (ChIP) assay demonstrated that AR binds with promoter region of has-miR-210-3p in the presence of androgen. CONCLUSIONS: Our observations indicated that miRNAs 203a/210-3p/5001-5p regulate the androgen/AR/YAP-induced PCa metastasis.

Intra-prostatic tumour evolution, steps in metastatic spread and histogenomic associations revealed by integration of multi-region whole-genome sequencing with histopathological features.

BACKGROUND: Extension of prostate cancer beyond the primary site by local invasion or nodal metastasis is associated with poor prognosis. Despite significant research on tumour evolution in prostate cancer metastasis, the emergence and evolution of cancer clones at this early stage of expansion and spread are poorly understood. We aimed to delineate the routes of evolution and cancer spread within the prostate and to seminal vesicles and lymph nodes, linking these to histological features that are used in diagnostic risk stratification. METHODS: We performed whole-genome sequencing on 42 prostate cancer samples from the prostate, seminal vesicles and lymph nodes of five treatment-naive patients with locally advanced disease. We spatially mapped the clonal composition of cancer across the prostate and the routes of spread of cancer cells within the prostate and to seminal vesicles and lymph nodes in each individual by analysing a total of > 19,000 copy number corrected single nucleotide variants. RESULTS: In each patient, we identified sample locations corresponding to the earliest part of the malignancy. In patient 10, we mapped the spread of cancer from the apex of the prostate to the seminal vesicles and identified specific genomic changes associated with the transformation of adenocarcinoma to amphicrine morphology during this spread. Furthermore, we show that the lymph node metastases in this patient arose from specific cancer clones found at the base of the prostate and the seminal vesicles. In patient 15, we observed increased mutational burden, altered mutational signatures and histological changes associated with whole genome duplication. In all patients in whom histological heterogeneity was observed (4/5), we found that the distinct morphologies were located on separate branches of their respective evolutionary trees. CONCLUSIONS: Our results link histological transformation with specific genomic alterations and phylogenetic branching. These findings have implications for diagnosis and risk stratification, in addition to providing a rationale for further studies to characterise the genetic changes causally linked to morphological transformation. Our study demonstrates the value of integrating multi-region sequencing with histopathological data to understand tumour evolution and identify mechanisms of prostate cancer spread.

PSMA-Targeted Therapy: Advancements in Detection and Treatment Modalities with Dr. Scott T. Tagawa.

Prostate cancer is one of the most challenging malignancies due to its high incidence and prevalence, as it is the most frequently diagnosed non-skin cancer in men. The timely identification of prostate cancer and its metastasis is paramount for ensuring favorable outcomes for patients. Prostate-specific membrane antigen (PSMA) emerges as a promising biomarker for its detection, due to its specificity. This makes it an ideal target for the early identification of a metastatic phenotype. Situated on the membrane of tumor cells, PSMA facilitates the attachment of PSMA-targeting particles, enabling their detection through positron emission tomography (PET) scans with relative ease. Utilizing these imaging agents in conjunction with PET scans enhances the accuracy of prostate cancer tumor detection compared to PET scans alone. The advancement in prostate cancer imaging has paved the way for innovative treatment modalities. Prostate-specific membrane antigen-targeted radionuclide therapies (PSMA-TRT) exploit PSMA imaging agents to target identified prostate cancer malignancies with precise radiation, thereby reducing or eliminating the tumor mass. PSMA-TRT exhibits significant promise in prostate cancer therapy, evident from the notable declines in prostate-specific antigen (PSA) levels post treatment. However, PSMA-TRT carries both beneficial and adverse effects. While it represents a substantial leap forward in tumor cell imaging, PSMA-based antigens, being larger particles than ligands, offer prolonged imaging capabilities. Yet, the long-term effects of PSMA-TRT remain unknown, with the short-term adverse ones including fatigue, nausea, pain flares, and potential radiation exposure to others.

Simultaneous targeting of AMPK and mTOR is a novel therapeutic strategy against prostate cancer.

Metastatic colonization by circulating cancer cells is a highly inefficient process. To colonize distant organs, disseminating cancer cells must overcome many obstacles in foreign microenvironments, and only a small fraction of them survives this process. How these disseminating cancer cells cope with stress and initiate metastatic process is not fully understood. In this study, we report that the metastatic onset of prostate cancer cells is associated with the dynamic conversion of metabolism signaling pathways governed by the energy sensors AMPK and mTOR. While in circulation in blood flow, the disseminating cancer cells display decreased mTOR and increased AMPK activities that protect them from stress-induced death. However, after metastatic onset, the mTOR-AMPK activities are reversed, enabling mTOR-dependent tumor growth. Suppression of this dynamic conversion by co-targeting of AMPK and mTOR signaling significantly suppresses prostate cancer cell and tumor organoid growth in vitro and experimental metastasis in vivo, suggesting that this can be a therapeutic approach against metastasizing prostate cancer.

PTEN regulated PI3K-p110 and AKT isoform plasticity controls metastatic prostate cancer progression.

PTEN loss, one of the most frequent mutations in prostate cancer (PC), is presumed to drive disease progression through AKT activation. However, two transgenic PC models with Akt activation plus Rb loss exhibited different metastasis development: Pten/RbPE:-/- mice produced systemic metastatic adenocarcinomas with high AKT2 activation, whereas RbPE:-/- mice deficient for the Src-scaffolding protein, Akap12, induced high-grade prostatic intraepithelial neoplasias and indolent lymph node disseminations, correlating with upregulated phosphotyrosyl PI3K-p85α. Using PC cells isogenic for PTEN, we show that PTEN-deficiency correlated with dependence on both p110ß and AKT2 for in vitro and in vivo parameters of metastatic growth or motility, and with downregulation of SMAD4, a known PC metastasis suppressor. In contrast, PTEN expression, which dampened these oncogenic behaviors, correlated with greater dependence on p110α plus AKT1. Our data suggest that metastatic PC aggressiveness is controlled by specific PI3K/AKT isoform combinations influenced by divergent Src activation or PTEN-loss pathways.

Vitamin D deficiency aggravates growth and metastasis of prostate cancer through promoting EMT in two ß-catenin-related mechanisms.

Increasing evidence has demonstrated that vitamin D deficiency is associated with prostate cancer progression, but its mechanism remains unclear. This study investigated effects of vitamin D deficiency on growth and metastasis of prostate cancer. Nude mice and Transgenic adenocarcinoma of the mouse prostate (TRAMP) mice were fed with vitamin D-deficient (VDD) diets. Prostate cancer growth was aggravated in VDD diet-fed nude mice and TRAMP mice. Invasion and metastasis of prostate cancer were exacerbated in VDD diet-fed TRAMP mice. In vitro experiments showed that calcitriol, an active vitamin D3, inhibited migration and invasion in transforming growth factor (TGF)-ß1 -stimulated and -unstimulated PC-3 and DU145 cells. Mechanistically, calcitriol inhibited epithelial-mesenchymal transition (EMT) in TGF-ß1 -stimulated and -unstimulated DU145 cells. Unexpectedly, calcitriol did not inhibit Smad2/3 phosphorylation in TGF-ß1-stimulated DU145 cells. Instead, calcitriol downregulated expression of proliferation-, metastasis- and EMT-related genes, includes Cyclin D1, MMP7, and Zeb1, by inhibiting interaction between TCF4 and ß-catenin. In addition, calcitriol promoted interaction between cytoplasmic VDR and ß-catenin, reduced ß-catenin phosphorylation and elevated ß-catenin/E-cadherin adherens junction complex formation. We provide novel evidence that vitamin D deficiency aggravates growth and metastasis of prostate cancer possibly through promoting EMT in two ß-catenin-related mechanisms.

Cancer origin tracing and timing in two high-risk prostate cancers using multisample whole genome analysis: prospects for personalized medicine.

BACKGROUND: Prostate cancer (PrCa) genomic heterogeneity causes resistance to therapies such as androgen deprivation. Such heterogeneity can be deciphered in the context of evolutionary principles, but current clinical trials do not include evolution as an essential feature. Whether or not analysis of genomic data in an evolutionary context in primary prostate cancer can provide unique added value in the research and clinical domains remains an open question. METHODS: We used novel processing techniques to obtain whole genome data together with 3D anatomic and histomorphologic analysis in two men (GP5 and GP12) with high-risk PrCa undergoing radical prostatectomy. A total of 22 whole genome-sequenced sites (16 primary cancer foci and 6 lymph node metastatic) were analyzed using evolutionary reconstruction tools and spatio-evolutionary models. Probability models were used to trace spatial and chronological origins of the primary tumor and metastases, chart their genetic drivers, and distinguish metastatic and non-metastatic subclones. RESULTS: In patient GP5, CDK12 inactivation was among the first mutations, leading to a PrCa tandem duplicator phenotype and initiating the cancer around age 50, followed by rapid cancer evolution after age 57, and metastasis around age 59, 5 years prior to prostatectomy. In patient GP12, accelerated cancer progression was detected after age 54, and metastasis occurred around age 56, 3 years prior to prostatectomy. Multiple metastasis-originating events were identified in each patient and tracked anatomically. Metastasis from prostate to lymph nodes occurred strictly ipsilaterally in all 12 detected events. In this pilot, metastatic subclone content analysis appears to substantially enhance the identification of key drivers. Evolutionary analysis' potential impact on therapy selection appears positive in these pilot cases. CONCLUSIONS: PrCa evolutionary analysis allows tracking of anatomic site of origin, timing of cancer origin and spread, and distinction of metastatic-capable from non-metastatic subclones. This enables better identification of actionable targets for therapy. If extended to larger cohorts, it appears likely that similar analyses could add substantial biological insight and clinically relevant value.

TLK1-mediated MK5-S354 phosphorylation drives prostate cancer cell motility and may signify distinct pathologies.

Metastases account for the majority of prostate cancer (PCa) deaths, and targeting them is a major goal of systemic therapy. We identified a novel interaction between two kinases: tousled-like kinase 1 (TLK1) and MAP kinase-activated protein kinase 5 (MK5) that promotes PCa spread. In PCa progression, TLK1-MK5 signalling appears to increase following antiandrogen treatment and in metastatic castration-resistant prostate cancer (mCRPC) patients. Determinations of motility rates (2D and 3D) of different TLK1- and MK5-perturbed cells, including knockout (KO) and knockdown (KD), as well as the use of specific inhibitors, showed the importance of these two proteins for in vitro dissemination. We established that TLK1 phosphorylates MK5 on three residues (S160, S354 and S386), resulting in MK5 activation, and additionally, mobility shifts of MK5 also supported its phosphorylation by TLK1 in transfected HEK 293 cells. Expression of MK5-S354A or kinase-dead MK5 in MK5-depleted mouse embryonic fibroblast (MEF) cells failed to restore their motility compared with that of wild-type (WT) MK5-rescued MK5-/- MEF cells. A pMK5-S354 antiserum was used to establish this site as an authentic TLK1 target in androgen-sensitive human prostate adenocarcinoma (LNCaP) cells, and was used in immunohistochemistry (IHC) studies of age-related PCa sections from TRAMP (transgenic adenocarcinoma of the mouse prostate) mice and to probe a human tissue microarray (TMA), which revealed pMK5-S354 level is correlated with disease progression (Gleason score and nodal metastases). In addition, The Cancer Genome Atlas (TCGA) analyses of PCa expression and genome-wide association study (GWAS) relations identify TLK1 and MK5 as potential drivers of advanced PCa and as markers of mCRPC. Our work suggests that TLK1-MK5 signalling is functionally involved in driving PCa cell motility and clinical features of aggressiveness; hence, disruption of this axis may inhibit the metastatic spread of PCa.

Multivariate competing endogenous RNA network characterization for cancer microRNA biomarker discovery: a novel bioinformatics model with application to prostate cancer metastasis.

Background: MicroRNAs (miRNAs) are post-transcriptional regulators with potential as biomarkers for cancer management. Data-driven competing endogenous RNA (ceRNA) network modeling is an effective way to decipher the complex interplay between miRNAs and spongers. However, there are currently no general rules for ceRNA network-based biomarker prioritization. Methods and results: In this study, a novel bioinformatics model was developed by integrating gene expression with multivariate miRNA-target data for ceRNA network-based biomarker discovery. Compared with traditional methods, the structural vulnerability in the human long non-coding RNA (lncRNA)-miRNA-messenger RNAs (mRNA) network was comprehensively analyzed, and the single-line regulatory or competing mode among miRNAs, lncRNAs, and mRNAs was characterized and quantified as statistical evidence for miRNA biomarker identification. The application of this model to prostate cancer (PCa) metastasis identified a total of 12 miRNAs as putative biomarkers from the metastatic PCa-specific lncRNA-miRNA-mRNA network and nine of them have been previously reported as biomarkers for PCa metastasis. The receiver operating characteristic curve and cell line qRT-PCR experiments demonstrated the power of miR-26b-5p, miR-130a-3p, and miR-363-3p as novel candidates for predicting PCa metastasis. Moreover, PCa-associated pathways such as prostate cancer signaling, ERK/MAPK signaling, and TGF-ß signaling were significantly enriched by targets of identified miRNAs, indicating the underlying mechanisms of miRNAs in PCa carcinogenesis. Conclusions: A novel ceRNA-based bioinformatics model was proposed and applied to screen candidate miRNA biomarkers for PCa metastasis. Functional validations using human samples and clinical data will be performed for future translational studies on the identified miRNAs.

The TLK1-MK5 Axis Regulates Motility, Invasion, and Metastasis of Prostate Cancer Cells.

Background: Metastatic dissemination of prostate cancer (PCa) accounts for the majority of PCa-related deaths. However, the exact mechanism of PCa cell spread is still unknown. We uncovered a novel interaction between two unrelated promotility factors, tousled-like kinase 1 (TLK1) and MAPK-activated protein kinase 5 (MK5), that initiates a signaling cascade promoting metastasis. In PCa, TLK1−MK5 signaling might be crucial, as androgen deprivation therapy (ADT) leads to increased expression of both TLK1 and MK5 in metastatic patients, but in this work, we directly investigated the motility, invasive, and metastatic capacity of PCa cells following impairment of the TLK1 > MK5 axis. Results: We conducted scratch wound repair and transwell invasion assays with LNCaP and PC3 cells to determine if TLK1 and MK5 can regulate motility and invasion. Both genetic depletion and pharmacologic inhibition of TLK1 and MK5 resulted in reduced migration and invasion through a Matrigel plug. We further elucidated the potential mechanisms underlying these effects and found that this is likely due to the reorganization of the actin fibers at lamellipodia and the focal adhesions network, in conjunction with increased expression of some MMPs that can affect penetration through the ECM. PC3, a highly metastatic cell line when assayed in xenografts, was further tested in a tail-vein injection/lung metastasis model, and we showed that, following inoculation, treatment with GLPG0259 (MK5 specific inhibitor) or J54 (TLK1 inhibitor) resulted in the lung tumor nodules being greatly diminished in number, and for J54, also in size. Conclusion: Our data support that the TLK1−MK5 axis is functionally involved in driving PCa cell metastasis and clinical aggressiveness; hence, disruption of this axis may inhibit the metastatic capacity of PCa.

FcγRIIIa receptor interacts with androgen receptor and PIP5K1α to promote growth and metastasis of prostate cancer.

Low-affinity immunoglobulin gamma Fc region receptor III-A (FcγRIIIa) is a cell surface protein that belongs to a family of Fc receptors that facilitate the protective function of the immune system against pathogens. However, the role of FcγRIIIa in prostate cancer (PCa) progression remained unknown. In this study, we found that FcγRIIIa expression was present in PCa cells and its level was significantly higher in metastatic lesions than in primary tumors from the PCa cohort (P = 0.006). PCa patients with an elevated level of FcγRIIIa expression had poorer biochemical recurrence (BCR)-free survival compared with those with lower FcγRIIIa expression, suggesting that FcγRIIIa is of clinical importance in PCa. We demonstrated that overexpression of FcγRIIIa increased the proliferative ability of PCa cell line C4-2 cells, which was accompanied by the upregulation of androgen receptor (AR) and phosphatidylinositol-4-phosphate 5-kinase alpha (PIP5Kα), which are the key players in controlling PCa progression. Conversely, targeted inhibition of FcγRIIIa via siRNA-mediated knockdown or using its inhibitory antibody suppressed growth of xenograft PC-3 and PC-3M prostate tumors and reduced distant metastasis in xenograft mouse models. We further showed that elevated expression of AR enhanced FcγRIIIa expression, whereas inhibition of AR activity using enzalutamide led to a significant downregulation of FcγRIIIa protein expression. Similarly, inhibition of PIP5K1α decreased FcγRIIIa expression in PCa cells. FcγRIIIa physically interacted with PIP5K1α and AR via formation of protein-protein complexes, suggesting that FcγRIIIa is functionally associated with AR and PIP5K1α in PCa cells. Our study identified FcγRIIIa as an important factor in promoting PCa growth and invasion. Further, the elevated activation of FcγRIII and AR and PIP5K1α pathways may cooperatively promote PCa growth and invasion. Thus, FcγRIIIa may serve as a potential new target for improved treatment of metastatic and castration-resistant PCa.

Leptomeningeal Carcinomatosis of Metastatic Primary Prostate Cancer.

Leptomeningeal carcinomatosis (LC) is an uncommon complication of cancer in which the disease metastasizes to the meninges; it is estimated that this occurs in 5% of cancer patients and is most often terminal. LC has a median survival time of approximately 15.7 weeks [Leal et al., Curr Cancer Ther Rev. 2011;7(4):319-27]. Furthermore, metastasis from the prostate is exceptionally rare with only a few cases described in medical literature. Until recently, leptomeningeal disruption was very rare and cerebral involvement was irrelevant [Bubendorf et al., Hum Pathol. 2000;31(5):578-83; Schaller et al., Br J Cancer. 2000;77(12):2386-9]. With improved imaging, diagnostic modalities, and treatment with therapies that do not cross the blood-brain barrier, the incidence of LC has been on the rise [Batool and Kasi, StatPearls, https://www.ncbi.nlm.nih.gov/books/NBK499862/]. Diagnosis previously relied on biopsy, supported by lumbar puncture findings. We submit a case demonstrating progressive and consistent evidence of LC found on imaging, justifying its acceptance as a diagnostic modality.

Loss of CDCP1 triggers FAK activation in detached prostate cancer cells.

A major metastasis suppressing mechanism is the rapid apoptotic death of cancer cells upon detachment from extracellular matrix, a process called anoikis. Focal adhesion kinase (PTK2/FAK) is a key enzyme involved in evasion of anoikis. We show that loss of the Cub-domain containing protein-1 (CDCP1), paradoxically stimulates FAK activation in the detached state of prostate cancer cells. In CDCP1low DU145 and PC3 prostate cancer cells, detachment-activation of FAK occurs through local production of PI(4,5)P2. PI(4,5)P2 is generated by the PIP5K1c-201 splicing isoform of PIP5K1c, which contains a unique SRC phosphorylation site. In the detached state, reduced expression of CDCP1 and an alternative CDCP1-independent SRC activation mechanism triggers PIP5K1c-pY644 phosphorylation by SRC. This causes a switch of Talin binding from ß1-integrin to PIP5K1c-pY644 and leads to activation of PIP5K1c-FAK. Reduced CDCP1 expression also inactivates CDK5, a negative regulator of PIP5K1c. Furthermore, immersion of prostate cancer cells in 10% human plasma or fetal bovine serum is required for activation of PIP5K1c-FAK. The PIP5K1c induced detachment-activation of FAK in preclinical models sensitizes CDCP1low prostate cancer cells to FAK inhibitors. In patients, CDCP1High versus CDCP1low circulating tumor cells differ in expression of AR-v7, ONECUT2 and HOXB13 oncogenes and TMPRSS2 and display intra-patient heterogeneity of FAK-pY397 expression. Taken together, CDCP1low and CDCP1high detached prostate cancer cells activate distinct cytoplasmic kinase complexes and targetable transcription factors, which has important therapeutic implications.