Caffeic Acid Phenethyl Ester Causes p21Cip1 Induction, Akt Signaling Reduction, and Growth Inhibition in PC-3 Human Prostate Cancer Cells

Caffeic acid phenethyl ester (CAPE) treatment suppressed proliferation, colony formation, and cell cycle progression in PC-3 human prostate cancer cells. CAPE decreased protein expression of cyclin D1, cyclin E, SKP2, c-Myc, Akt1, Akt2, Akt3, total Akt, mTOR, Bcl-2, Rb, as well as phosphorylation of Rb, ERK1/2, Akt, mTOR, GSK3α, GSK3β, PDK1; but increased protein expression of KLF6 and p21Cip1. Microarray analysis indicated that pathways involved in cellular movement, cell death, proliferation, and cell cycle were affected by CAPE. Co-treatment of CAPE with chemotherapeutic drugs vinblastine, paclitaxol, and estramustine indicated synergistic suppression effect. CAPE administration may serve as a potential adjuvant therapy for prostate cancer

Non-Canonical Wnt receptor ROR2 suppresses prostate cancer metastasis

[[abstract]]Prostate cancer (PCa) ranks the 5th most common cancer in the world. Receptor tyrosine-kinase like orphan receptor 2 (ROR2) is a regulator of non-canonical Wnt signaling. Expression of mRNA and protein of ROR2 was analyzed in clinical samples with qRT-PCR and IHC staining. Tranwell assays and wound healing assay were performed to determine the roles of ROR2 on migration and invasion of PCa cells. Micro-Western Array MWA platform was introduced to determine downstream signaling network regulated by ROR2. Analysis of ROR2 gene expression level in a total of 249 normal prostate tissues, benign prostate hyperplasia BPH, and prostate tumors revealed that ROR2 mRNA level is the lowest in metastatic PCa. IHC staining analysis of 48 PCa tissues indicated that ROR2 expression inversely correlated to aggressiveness of PCa...

ACTL6A is a novel oncogene and prognostic biomarker for prostate cancer

[[abstract]]ACTL6A (Actin-like 6A protein) is a member of ATP-dependent SWI/SNF-like BAF chromatin remodeling complexes encoding a family of actin-related proteins. Using 3D culture and Micro-Western Array analysis targeting for epigenetic regulatory proteins, we discovered that ACTL6A plays essential role in regulation of the prostate acinar morphogenesis, a differentiation procedure. Expression level of ACTL6A protein decreases dramatically during prostate acinar morphogenesis, suggesting that ACTL6A is a potential oncogene in prostate cancer (PCa). We analyzed Oncomine online database and found that ACTL6A is higher in prostate cancer vs. adjacent normal prostate tissues, while ACTL6A protein level is even higher in metastatic PCa. High ACTL6A gene expression level in prostate tumors correlates to worse PCa patient survival outcome. We knocked down ACTL6A in PC-3 PCa cells, and the reduction of ACTL6A suppressed proliferation, migration, and invasion of PC-3 cells. Knockdown of ACTL6A also reduced population of CD44+ and ALDH enzyme activity-positive PCa cells, which represents the population of cancer stem cell (CSC) in PCa. Decrease of ACTL6A reduced expression of a few oncogenic long non-coding RNA, including HIFCAR, MALAT1, and PCAT-1. Seahorse mito-stress and glycol-stress analysis revealed that knockdown of ACTL6A suppressed OCR and ECAR of mitochondria in PCa cells. ACTL6A knockdown up-regulates expression of glycolysis-related genes, suggesting that ACTL6A regulate cancer metabolism. Our study suggested that ACTL6A regulates expression and activity of YAP and c-Myc, which in turn regulates stemness factors Nanog and Sox2, thus enhances the cancer stemness of PCa cells. ACTL6A also regulates mitochondrial function and metabolic genes PKM2, LDHA, GLS1, partially through c-Myc, therefore ACTL6A causes metabolism rewiring in PCa. All these regulations contribute to the metastasis of PCa. In conclusion, ACTL6A is a novel oncogene and prognostic biomarker for PCa

Caffeic acid phenethyl ester suppresses drug resistance of enzalutamide or abiraterone in prostate cancer cells

[[abstract]]Enzalutamide (ENZ) and Abiraterone acetate (AA) are drugs targeting androgen receptor axis for treatment of metastatic castration-resistant prostate cancer (mCRPC). However, a majority of patients receiving these treatments will eventually acquire drug resistance, which is caused by multiple mechanisms including the activation of AR splice variant 7 (AR-V7). We determined if caffeic acid phenethyl ester (CAPE) can suppress the signaling of AR-V7 and tumor growth of ENZ-resistant or AA-resistant mCRPC cells. CAPE treatment dose-dependently suppressed the transcriptional activity of AR-V7, its target gene UBE2C and TMPRSS2, and its splicing factors U2AF65, SF2 and HNRNPF. Cyclohexamide treatment and MG132 treatment revealed that stability of AR-V7 was reduced by CAPE and CAPE increased AR-V7 tagged for the proteasomal degradation. Fluorescence microscopy demonstrated that treatment with CAPE reduced nuclear accumulation of AR-V7 as well as phosphorylation of Ser81 and Ser213 on AR-V7, which decreases the stability and abundance of AR-V7. CAPE inhibits the expression of CDK1 and AKT, the two kinases phosphorylating Ser81 and Ser213 on AR, respectively. Overexpression of CDK1, AKT, or c-Myc rescued the AR-V7 protein level under CAPE treatment. Injection of CAPE repressed tumor growth of 22Rv1 xenografts as well as AR-V7, CDK1 and AKT expression in tumors. Combined treatment of CAPE and ENZ or AA suppress the proliferation of enzalutamide-resistant or Abiraterone-resistant CRPC cells via inhibition of AR-V7. Our results suggested that CAPE treatment reduced expression level, stability and transcriptional activity of AR-V7 in CRPC cells, and thus prevented implying the development of resistance against enzalutamide and abiraterone via inhibition of AR-V7. CAPE may be a promising therapeutic agent for enzalutamide-resistant or abiraterone-resistant CRPC

Proteomics profiling of epigenetic proteins during acinar morphogenesis to identify prostate cancer prognostic markers

[[abstract]]Background: Prostate cancer (PCa) is the 5th most common cancer overall in the world. Epigenetic alterations have been shown to be involved in the development or progression of cancer via regulation of histone modifications. Methods: In this study, we use the state-of-the-art Micro-Western Array (MWA) for protein profiling study. MWA is a protein array composes of a GeSim Nanoplotter arrayer, a GE multiphor, and a Licor Odyssey infra-red scanner. MWA allows detecting protein expression level or phosphorylation status change of 96-384 different antibodies in 6-15 samples simultaneously but the quantity of samples and antibodies required for MWA is approximately 500-1000 fold less than the conventional Western blotting. We use MWA with 512 antibodies to analyze the human prostatic acinar of RWPE-1 generated prostate epithelial cells in a three-dimensional (3D) basement membrane (BM) that recapitulates the differentiated morphological characteristics and protein expression profile of a human prostate glandular epithelial tissue. Results: We observed 20 up-regulated and 21 down-regulated protein candidates significantly change during RWPE-1 polarization process from cluster to acinar in 3D microenvironment. We applied the acinar morphogenesis-specific protein profile to cohort of patients with prostate cancer (n = 50) and we discovered that 12-protein acinar differentiation-related epigenetic signature can effectively predict the clinical prognosis of prostate cancer recurrent disease after surgery. Among the epigenetic proteins, histone lysine demethylases proteins KDM4A, KDM4B, and KDM4C can modulate androgen receptor (AR)-mediated transcription and share high similarity. However, they exhibit different regulatory effects on cell proliferation, cancer metastasis, and prostate acinar morphogenesis and can be therapeutic targets for PCa. Conclusion: Our study suggests that tissue architecture-specific epigenetic proteins are useful prognostic markers for PCa

Androgen suppresses proliferation of castration-resistant LNCaP 104-R2 prostate cancer cells through androgen receptor, Skp2, and c-Myc

[[abstract]]Androgen ablation therapy is the primary treatment for metastatic prostate cancer. However, this therapy is associated with several undesired side-effects, including increased risk of cardiovascular diseases. To study if termination of long-term androgen ablation and restoring testosterone level may suppress the growth of relapsed hormone-refractory prostate tumors, we implanted testosterone pellets in castrated nude mice carrying androgen receptor (AR)-positive LNCaP 104-R2 cells, which relapsed from androgen-dependent LNCaP 104-S cells after long-term androgen deprivation. 104-R2 tumor xenografts regressed after testosterone pellets implant. 24 out of 33 tumors adapted to elevation of testosterone level and relapsed as androgen-insensitive tumors. Relapsed tumors (R2Ad) expressed less AR and prostate-specific antigen (PSA). We then study the molecular mechanism lying underneath the androgenic regulation of prostate cancer cell proliferation. Androgen suppresses proliferation of 104-R2 by inducing G1 cell cycle arrest via reduction of Skp2 and c-Myc, and induction of p27(Kip1) . 104-R2 cells adapted to androgen treatment and the adapted cells, R2Ad, were androgen-insensitive cells with slower growing rate and low protein level of AR, high levels of c-Myc and Skp2, and low levels of p27(Kip1) . Nuclear AR and PSA expression is present in 104-R2 cells but not R2Ad cells when androgen is absent. Overexpression of AR in R2Ad cells regenerated an androgen-repressed phenotype, while knockdown of AR in 104-R2 cells generated an androgen-insensitive phenotype. Overexpression of Skp2 and c-Myc in 104-R2 cells blocked the growth inhibition caused by androgens. We concluded that androgens cause growth inhibition in LNCaP 104-R2 prostate cancer cells via AR, Skp2, and c-Myc

Modulation of liver X receptor signaling as a prevention and therapy for colon cancer

[[abstract]]Liver X receptors (LXRalpha and LXRbeta) are members of the nuclear receptor family and are important regulators of cholesterol, fatty acid, and glucose homeostasis. LXR agonists are effective for treatment of murine models of atherosclerosis, diabetes, and Alzheimer's disease. Recently we and other groups observed that LXR agonists suppressed proliferation of multiple human cancer cell lines in vitro as well as suppressed the growth and progression of prostate tumor xenografts in nude mice. LXR agonists appear to cause G1 cell cycle arrest in cancer cells by reducing the protein expression level of Skp2, cyclin A2, cyclin D1, and the phosphorylation of Rb, while increasing the protein expression level of cell cycle inhibitor p27(Kip1) and p53. LXR agonist also suppressed the oncogenic activity of beta-catenin, an important regulator in Wnt signaling, as well as the proliferation in human colon cancer cells. Phytosterols, the plant equivalent of mammalian cholesterol, have been shown to be agonists for LXRs. Intake of phytosterol-rich diets reduced the incidence of colon cancer. We therefore propose that activation of LXR signaling via treatment with LXR agonists or intake of phytosterols-rich diets can reduce the incidence and suppress the tumor growth of colon cancer