Chloroquine treatment induces secretion of autophagy-related proteins and inclusion of Atg8-family proteins in distinct extracellular vesicle populations.

Chloroquine (CQ), a lysosomotropic agent, is commonly used to inhibit lysosomal degradation and macroautophagy/autophagy. Here we investigated the cell-extrinsic effects of CQ on secretion. We showed that lysosomal and autophagy inhibition by CQ altered the secretome, and induced the release of Atg8 orthologs and autophagy receptors. Atg8-family proteins, in particular, were secreted inside small extracellular vesicles (sEVs) in a lipidation-dependent manner. CQ treatment enhanced the release of Atg8-family proteins inside sEVs. Using full-length ATG16L1 and an ATG16L1 mutant that enables Atg8-family protein lipidation on double but not on single membranes, we demonstrated that LC3B is released in two distinct sEV populations: one enriched with SDCBP/Syntenin-1, CD63, and endosomal lipidated LC3B, and another that contains LC3B but is not enriched with SDCBP/Syntenin-1 or CD63, and which our data supports as originating from a double-membrane source. Our findings underscore the context-dependency of sEV heterogeneity and composition, and illustrate the integration of autophagy and sEV composition in response to lysosomal inhibition.Abbreviations: ACTB: actin beta; ANOVA: analysis of variance; ATG4B: autophagy related 4B cysteine peptidase; Atg8: autophagy related 8; ATG16L1: autophagy related 16 like 1; ATP5F1A/ATP5a: ATP synthase F1 subunit alpha; CALCOCO2: calcium binding and coiled-coil domain 2; CASP3: caspase 3; CASP7: caspase 7; CQ: chloroquine; CD9: CD9 molecule; CD63: CD63 molecule; DAPI: 4',6-diamidino-2-phenylindole; DQ-BSA: dye quenched-bovine serum albumin; ER: endoplasmic reticulum; ERN1/IRE1a: endoplasmic reticulum to nucleus signaling 1; EV: extracellular vesicles; FBS: fetal bovine serum; FDR: false discovery rate; GABARAP: GABA type A receptor-associated protein; GABARAPL2: GABA type A receptor associated protein like 2; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GFP: green fluorescent protein; GO: gene ontology; HCQ: hydroxychloroquine; HSP90AA1: heat shock protein 90 alpha family class A member 1; IP: immunoprecipitation; KO: knockout; LAMP2: lysosomal associated membrane protein 2; LIR: LC3-interacting region; LMNA: lamin A/C; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; MS: mass spectrometry; NBR1: NBR1 autophagy cargo receptor; NCOA4: nuclear receptor coactivator 4; NTA: nanoparticle tracking analysis; PE: phosphatidylethanolamine; PECA: probe-level expression change averaging; SDCBP/syntenin-1: syndecan binding protein; SD: standard deviation; SE: secreted; sEV: small extracellular vesicles; SQSTM1/p62: sequestosome 1; TAX1BP1: Tax1 binding protein 1; TEM: transmission electron microscopy; TMT: tandem-mass tag; TSG101: tumor susceptibility 101; ULK1: unc-51 like autophagy activating kinase 1; WC: whole cell.

Identification of a Hematopoietic Cell Dedifferentiation-Inducing Factor.

It has long been realized that hematopoietic cells may have the capacity to trans-differentiate into non-lymphohematopoietic cells under specific conditions. However, the mechanisms and the factors for hematopoietic cell trans-differentiation remain unknown. In an in vitro culture system, we found that using a conditioned medium from proliferating fibroblasts can induce a subset of hematopoietic cells to become adherent fibroblast-like cells (FLCs). FLCs are not fibroblasts nor other mesenchymal stromal cells, based on their expression of type-1 collagen, and other stromal cell marker genes. To identify the active factors in the conditioned medium, we cultured fibroblasts in a serum-free medium and collected it for further purification. Using the fractions from filter devices of different molecular weight cut-offs, and ammonium sulfate precipitation collected from the medium, we found the active fraction is a protein. We then purified this fraction by using fast protein liquid chromatography (FPLC) and identified it by mass spectrometer as macrophage colony-stimulating factor (M-CSF). The mechanisms of M-CSF-inducing trans-differentiation of hematopoietic cells seem to involve a tyrosine kinase signalling pathway and its known receptor. The FLCs express a number of stem cell markers including SSEA-1 and -3, OCT3/4, NANOG, and SOX2. Spontaneous and induced differentiation experiments confirmed that FLCs can be further differentiated into cell types of three germ layers. These data indicate that hematopoietic cells can be induced by M-CSF to dedifferentiate to multipotent stem cells. This study also provides a simple method to generate multipotent stem cells for clinical applications.

Identification of a potent antiandrogen that targets the BF3 site of the androgen receptor and inhibits enzalutamide-resistant prostate cancer.

There has been a resurgence of interest in the development of androgen receptor (AR) inhibitors with alternative modes of action to overcome the development of resistance to current therapies. We demonstrated previously that one promising strategy for combatting mutation-driven drug resistance is to target the Binding Function 3 (BF3) pocket of the receptor. Here we report the development of a potent BF3 inhibitor, 3-(2,3-dihydro-1H-indol-2-yl)-1H-indole, which demonstrates excellent antiandrogen potency and anti-PSA activity and abrogates the androgen-induced proliferation of androgen-sensitive (LNCaP) and enzalutamide-resistant (MR49F) PCa cell lines. Moreover, this compound effectively reduces the expression of AR-dependent genes in PCa cells and effectively inhibits tumor growth in vivo in both LNCaP and MR49F xenograft models. These findings provide evidence that targeting the AR BF3 pocket represents a viable therapeutic approach to treat patients with advanced and/or resistant prostate cancer.

Pomegranate extracts impact the androgen biosynthesis pathways in prostate cancer models in vitro and in vivo.

Castration-resistant prostate cancer (CRPC) remains largely dependent on androgen receptor (AR). Residual tissue androgens are consistently detected within CRPC tumors and play a critical role in facilitating AR-mediated signaling pathways which lead to disease progression. Testosterone and dihydrotestosterone (DHT) are the major androgens detected in tumors. They are produced through three biosynthesis pathways: Δ(4), Δ(5), and backdoor pathways. Both androgens bind to and stimulate AR activation. The current study investigates the effects of pomegranate extracts (POM) and their ability to inhibit androgen biosynthesis using PCa cell lines (22RV1 and LNCaP) in vitro as well as the PTEN knockout mouse model representing prostate cancer. Steroids were extracted using ethyl acetate or solid phase extraction, and then analyzed by UPLC/MS/MS. The results showed that POM (0-12µg/mL) reduced the production of testosterone, DHT, DHEA, androstenedione, androsterone, and pregnenolone in both cell lines. In addition our in vivo data supports this observation with a reduction in serum steroids determined after 20 weeks of POM treatment (0.17 g/L in drinking water). In accordance with these results, Western blotting of cell lysates and tPSA analysis determined that PSA was significantly decreased by the treatment of POM. Interestingly, AKR1C3 and AR levels were shown to be increased in both cell lines, perhaps as a negative feedback effect in response to steroid inhibition. Overall, these results provide mechanistic evidence to support the rationale for recent clinical reports describing efficacy of POM in CRPC patients.

Characterization of a new class of androgen receptor antagonists with potential therapeutic application in advanced prostate cancer.

The human androgen receptor plays a major role in the development and progression of prostate cancer and represents a well-established drug target. All clinically approved androgen receptor antagonists possess similar chemical structures and exhibit the same mode of action on the androgen receptor. Although initially effective, resistance to these androgen receptor antagonists usually develops and the cancer quickly progresses to castration-resistant and metastatic states. Yet even in these late-stage patients, the androgen receptor is critical for the progression of the disease. Thus, there is a continuing need for novel chemical classes of androgen receptor antagonists that could help overcome the problem of resistance. In this study, we implemented and used the synergetic combination of virtual and experimental screening to discover a number of new 10-benzylidene-10H-anthracen-9-ones that not only effectively inhibit androgen receptor transcriptional activity, but also induce almost complete degradation of the androgen receptor. Of these 10-benzylidene-10H-anthracen-9-one analogues, a lead compound (VPC-3033) was identified that showed strong androgen displacement potency, effectively inhibited androgen receptor transcriptional activity, and possesses a profound ability to cause degradation of androgen receptor. Notably, VPC-3033 exhibited significant activity against prostate cancer cells that have already developed resistance to the second-generation antiandrogen enzalutamide (formerly known as MDV3100). VPC-3033 also showed strong antiandrogen receptor activity in the LNCaP in vivo xenograft model. These results provide a foundation for the development of a new class of androgen receptor antagonists that can help address the problem of antiandrogen resistance in prostate cancer.

Allelic loss of the loci containing the androgen synthesis gene, StAR, is prognostic for relapse in intermediate-risk prostate cancer.

BACKGROUND: Androgen deprivation therapy (ADT) and novel agents targeting the androgen synthesis axis (e.g., abiraterone acetate) are adjuvant therapies that are currently, or may in the future be, combined with radiotherapy to reduce the chance of disease relapse. Little is known about allelic loss or gain pertaining to genes associated with the androgen synthesis axis and whether this is prognostic in patients who receive localized radiotherapy. In this hypothesis generating study, we conducted an array comparative genomic hybridization (aCGH) analysis of 33 androgen synthesis genes to identify potential prognostic factors for radiotherapy outcome. METHODS: aCGH analysis of tumor DNA prospectively derived from frozen needle biopsies of 126 men with intermediate-risk disease who underwent image-guided radiotherapy (IGRT) to a mean dose of 76.4 Gy was conducted. Statistical analyses were conducted for allelic loss or gain in genes as potential prognostic factors relative to prostate specific antigen, Gleason-score, and T-category. RESULTS: We observed that allelic losses of loci containing the genes StAR and HSD17B2 were associated with increased genetic instability (as determined by percentage genome alteration). On multivariate analyses these loci were prognostic for biochemical disease-free relapse (StAR: HR = 2.84, 95% CI: 1.44-5.61, P = 0.00269; HSD17B2: HR = 1.97, 95% CI: 1.06-3.64, P = 0.031). The results were validated in a surgical cohort of 131 intermediate-risk patients. CONCLUSIONS: Allelic losses of the loci containing StAR and HSD17B2 have significant prognostic value for intermediate-risk prostate cancer. With this hypothesis generating information future studies should test StAR and HSD17B2 losses as biomarkers of androgen response in combined modality protocols.

Targeting the binding function 3 (BF3) site of the human androgen receptor through virtual screening.

The androgen receptor (AR) is the best studied drug target for the treatment of prostate cancer. While there are a number of drugs that target the AR, they all work through the same mechanism of action and are prone to the development of drug resistance. There is a large unmet need for novel AR inhibitors which work through alternative mechanism(s). Recent studies have identified a novel site on the AR called binding function 3 (BF3) that is involved into AR transcriptional activity. In order to identify inhibitors that target the BF3 site, we have conducted a large-scale in silico screen followed by experimental evaluation. A number of compounds were identified that effectively inhibited the AR transcriptional activity with no obvious cytotoxicity. The mechanism of action of these compounds was validated by biochemical assays and X-ray crystallography. These findings lay a foundation for the development of alternative or supplementary therapies capable of combating prostate cancer even in its antiandrogen resistant forms.

Antiandrogenic and growth inhibitory effects of ring-substituted analogs of 3,3'-diindolylmethane (ring-DIMs) in hormone-responsive LNCaP human prostate cancer cells.

BACKGROUND: Cruciferous vegetables protect against prostate cancer. Indole-3-carbinol (I3C) and its major metabolite 3,3'-diindolylmethane (DIM), exhibit antitumor activities in vitro and in vivo. Several synthetic ring-substituted dihaloDIMs (ring-DIMs) appear to have increased anticancer activity. METHODS: Inhibition of LNCaP prostate cancer cell growth was measured by a WST-1 cell viability assay. Cytoplasmic and nuclear proteins were analyzed by immunoblotting and immunofluorescence. Androgen receptor (AR) activation was assessed by measuring prostate-specific antigen (PSA) expression and using LNCaP cells containing human AR and an AR-dependent probasin promoter-green fluorescent protein (GFP) construct. RESULTS: Like DIM, several ring-substituted dihaloDIM analogs, namely 4,4'-dibromo-, 4,4'-dichloro-, 7,7'-dibromo-, and 7,7'-dichloroDIM, significantly inhibited DHT-stimulated growth of LNCaP cells at concentrations ≥1 µM. We observed structure-dependent differences for the effects of the ring-DIMs on AR expression, nuclear AR accumulation and PSA levels in LNCaP cells after 24 hr. Both 4,4'- and 7,7'-dibromoDIM decreased AR protein and mRNA levels, whereas 4,4'- and 7,7'-dichloroDIM had minimal effect. All four dihaloDIMs (10 and 30 µM) significantly decreased PSA protein and mRNA levels. Immuofluorescence studies showed that only the dibromoDIMs increased nuclear localization of AR. All ring-DIMs caused a concentration-dependent decrease in fluorescence induced by the synthetic androgen R1881 in LNCaP cells transfected with wild-type human AR and an androgen-responsive probasin promoter-GFP gene construct, with potencies up to 10-fold greater than that of DIM. CONCLUSION: The antiandrogenic effects of ring-DIMs suggest they may form the basis for the development of novel agents against hormone-sensitive prostate cancer, alone or in combination with other drugs.

Rh2 or its aglycone aPPD in combination with docetaxel for treatment of prostate cancer.

BACKGROUND: Docetaxel is one of the few chemotherapeutic drugs that are considered highly effective when used to treat prostate cancer patients that have relapsed and/or metastatic disease, it is therefore reasonable to expect further improvements in treatment outcomes when it is combined with other therapeutic agents active in prostate cancer. This study assesses the combination of well tolerated and orally bioavailable formulations of ginsenoside Rh2 or its aglycone aPPD with docetaxel. METHODS: The in vitro activity of Rh2, aPPD, and docetaxel was determined in four prostate cancer cell lines: PC-3, LNCaP, DU145, and C4-2. Combinations of Rh2 or aPPD with docetaxel were assessed using the constant ratio combination design. Combination Indices (CI) and Dose Reduction Indices (DRI) were subsequently estimated using Calcusyn. In vivo efficacy studies and Immunohistochemical analyses (PC-3 model) were also evaluated. RESULTS: In PC-3, DU145 and C4-2 prostate cancer cells combinations of Rh2 or aPPD with docetaxel were predominantly additive or synergistic. Combinations of Rh2 + docetaxel and aPPD + docetaxel caused established PC-3 tumors to regress from their initial size by 15% and 27%, respectively. Tumor cell proliferation rate (measured by Ki-67 positive cells) was significantly lower for combinations of Rh2 + docetaxel and aPPD + docetaxel, compared to animals treated with docetaxel alone. CONCLUSIONS: Rh2 and aPPD can be combined with docetaxel to yield additive or synergistic activity in vitro and in vivo. Pending further assessment of toxicity and pharmacodynamic behavior, this study supports testing of combinations of ginsenoside Rh2 or its aglycone aPPD with docetaxel in a clinical setting.

Pre-clinical evaluation of Rh2 in PC-3 human xenograft model for prostate cancer in vivo: formulation, pharmacokinetics, biodistribution and efficacy.

PURPOSE: This study assesses the pharmacokinetics, biodistribution and efficacy of ginsenoside Rh2 as a single agent administered in a novel oral dosage formulation. METHODS: A novel oral dosage formulation of Rh2 has been described. Rh2 levels in blood and tissues following administration to nu/nu nude mice were determined by high performance liquid chromatography tandem mass spectroscopy. Efficacy was determined in an established PC-3 human prostate cancer model. RESULTS: Rh2 administered at a dose of 120 mg/kg exhibited a peak plasma concentration of 19.0 +/- 2.0 microg/ml. Rh2 levels were measurable in prostate and tumor tissues, with as much as 0.3% of the administered dose being detected in tumors. This formulation exhibited no measurable toxicity as judged by weight loss or changes in serum levels of aspartate aminotransferase, alanine aminotransferase, and creatinine. This dose engendered a significant delay in PC-3 tumor growth, an increase in apoptotic index, and a decrease in tumor cell proliferation. CONCLUSIONS: Rh2 is a stable compound that can be formulated for oral gavage. Pharmacokinetics studies demonstrate its ability to be absorbed following oral administration. Future studies will assess the pharmacokinetics of Rh2 when administered in combination with docetaxel.