Autophagy in prostate cancer and androgen suppression therapy. Int J Mol Sci. 2013;14:12090-12106. [PMID: 23743823 DOI: 10.3390/ijms140612090]

CAPN2 promotes apalutamide resistance in metastatic hormone-sensitive prostate cancer by activating protective autophagy

Apalutamide, a novel endocrine therapy agent, has been shown to significantly improve the prognosis of patients with metastatic hormone-sensitive prostate cancer (mHSPC). However, resistance to apalutamide has also been reported, and the underlying mechanism for this response has yet to be clearly elucidated. First, this study established apalutamide-resistant prostate cancer (PCa) cells, and confirmed that apalutamide activated the release of calcium ions (Ca2+) and endoplasmic reticulum stress (ERS) to enhance autophagy. Second, RNA sequencing, western blotting, and immunohistochemistry revealed significantly decreased Calpain 2 (CAPN2) expression in the apalutamide-resistant PCa cells and tissues. Furthermore, immunofluorescence and transmission electron microscopy (TEM) showed that CAPN2 promoted apalutamide resistance by activating protective autophagy. CAPN2 promoted autophagy by reducing Forkhead Box O1 (FOXO1) degradation while increasing nuclear translocation via nucleoplasmic protein isolation and immunofluorescence. In addition, FOXO1 promoted protective autophagy through the transcriptional regulation of autophagy-related gene 5 (ATG5). Furthermore, a dual-fluorescence assay confirmed that transcription factor 3 (ATF3) stimulation promoted CAPN2-mediated autophagy activation via transcriptional regulation. In summary, CAPN2 activated protective autophagy by inhibiting FOXO1 degradation and promoting its nuclear translocation via transcriptional ATG5 regulation. ATF3 activation and transcriptional CAPN2 regulation jointly promoted this bioeffect. Thus, our findings have not only revealed the mechanism underlying apalutamide resistance, but also provided a promising new target for the treatment of metastatic PCa.

From Androgen Dependence to Independence in Prostate Cancer: Unraveling Therapeutic Potential and Proteomic Landscape of Hydroxychloroquine as an Autophagy Inhibitor

Prostate cancer is a major planetary health challenge wherein new ways of thinking drug discovery and therapeutics innovation are much needed. Numerous studies have shown that autophagy inhibition holds a significant role as an adjunctive intervention in prostate cancer. Hydroxychloroquine (HCQ) has gained considerable attention due to its established role as an autophagy inhibitor across diverse cancer types, but its proteomics landscape and systems biology in prostate cancer are currently lacking in the literature. This study reports the proteomic responses to HCQ in prostate cancer cells, namely, androgen-dependent LNCaP and androgen-independent PC3 cells. Differentially expressed proteins and proteome in HCQ-treated cells were determined by label-free quantification with nano-high-performance liquid chromatography and tandem mass spectrometry (nHPLC-MS/MS), and harnessing bioinformatics tools. In PC3 cells, there was a marked shift toward metabolic reprogramming, highlighted by an upregulation of mitochondrial proteins in oxidative phosphorylation and tricarboxylic acid cycle, suggesting an adaptive mechanism to maintain energy production under therapeutic stress. In contrast, LNCaP cells prioritized proteostasis and cell cycle regulation, indicating a more conservative adaptation strategy. To the best of our knowledge, this study is the first to demonstrate the differential responses of prostate cancer cells to autophagy inhibition by HCQ, suggesting that a combination therapy approach, targeting distinct pathways in androgen-independent and androgen-dependent cells, could represent a promising treatment strategy. Moreover, the varied proteomic responses observed between these cell lines underscore the importance of personalized medicine in cancer therapy. Future translational and clinical research on HCQ and prostate cancer are called for.

Calotropis procera extract inhibits prostate cancer through regulation of autophagy

Current treatment options available for prostate cancer (PCa) patients have many adverse side effects and hence, new alternative therapies need to be explored. Anticancer potential of various phytochemicals derived from Calotropis procera has been studied in many cancers but no study has investigated the effect of leaf extract of C. procera on PCa cells. Hence, we investigated the effect of C. procera leaf extract (CPE) on cellular properties of androgen-independent PC-3 and androgen-sensitive 22Rv1 cells. A hydroalcoholic extract of C. procera was prepared and MTT assay was performed to study the effect of CPE on viability of PCa cells. The effect of CPE on cell division ability, migration capability and reactive oxygen species (ROS) production was studied using colony formation assay, wound-healing assay and 2',7'-dichlorodihydrofluorescein diacetate assay, respectively. Caspase activity assay and LDH assay were performed to study the involvement of apoptosis and necrosis in CPE-mediated cell death. Protein levels of cell cycle, antioxidant, autophagy and apoptosis markers were measured by western blot. The composition of CPE was identified using untargeted LC-MS analysis. Results showed that CPE decreased the viability of both the PCa cells, PC-3 and 22Rv1, in a dose- and time-dependent manner. Also, CPE significantly inhibited the colony-forming ability, migration and endogenous ROS production in both the cell lines. Furthermore, CPE significantly decreased NF-κB protein levels and increased the protein levels of the cell cycle inhibitor p27. A significant increase in expression of autophagy markers was observed in CPE-treated PC-3 cells while autophagy markers were downregulated in 22Rv1 cells after CPE exposure. Hence, it can be concluded that CPE inhibits PCa cell viability possibly by regulating the autophagy pathway and/or altering the ROS levels. Thus, CPE can be explored as a possible alternative therapeutic agent for PCa.

The Molecular Mechanism and Therapeutic Application of Autophagy for Urological Disease

Autophagy is a lysosomal degradation process known as autophagic flux, involving the engulfment of damaged proteins and organelles by double-membrane autophagosomes. It comprises microautophagy, chaperone-mediated autophagy (CMA), and macroautophagy. Macroautophagy consists of three stages: induction, autophagosome formation, and autolysosome formation. Atg8-family proteins are valuable for tracking autophagic structures and have been widely utilized for monitoring autophagy. The conversion of LC3 to its lipidated form, LC3-II, served as an indicator of autophagy. Autophagy is implicated in human pathophysiology, such as neurodegeneration, cancer, and immune disorders. Moreover, autophagy impacts urological diseases, such as interstitial cystitis /bladder pain syndrome (IC/BPS), ketamine-induced ulcerative cystitis (KIC), chemotherapy-induced cystitis (CIC), radiation cystitis (RC), erectile dysfunction (ED), bladder outlet obstruction (BOO), prostate cancer, bladder cancer, renal cancer, testicular cancer, and penile cancer. Autophagy plays a dual role in the management of urologic diseases, and the identification of potential biomarkers associated with autophagy is a crucial step towards a deeper understanding of its role in these diseases. Methods for monitoring autophagy include TEM, Western blot, immunofluorescence, flow cytometry, and genetic tools. Autophagosome and autolysosome structures are discerned via TEM. Western blot, immunofluorescence, northern blot, and RT-PCR assess protein/mRNA levels. Luciferase assay tracks flux; GFP-LC3 transgenic mice aid study. Knockdown methods (miRNA and RNAi) offer insights. This article extensively examines autophagy's molecular mechanism, pharmacological regulation, and therapeutic application involvement in urological diseases.

Autophagy, a critical element in the aging male reproductive disorders and prostate cancer: a therapeutic point of view

Autophagy is a highly conserved, lysosome-dependent biological mechanism involved in the degradation and recycling of cellular components. There is growing evidence that autophagy is related to male reproductive biology, particularly spermatogenic and endocrinologic processes closely associated with male sexual and reproductive health. In recent decades, problems such as decreasing sperm count, erectile dysfunction, and infertility have worsened. In addition, reproductive health is closely related to overall health and comorbidity in aging men. In this review, we will outline the role of autophagy as a new player in aging male reproductive dysfunction and prostate cancer. We first provide an overview of the mechanisms of autophagy and its role in regulating male reproductive cells. We then focus on the link between autophagy and aging-related diseases. This is followed by a discussion of therapeutic strategies targeting autophagy before we end with limitations of current studies and suggestions for future developments in the field.

Tumor acidity-activatable macromolecule autophagy inhibitor and immune checkpoint blockade for robust treatment of prostate cancer

Immune checkpoint blockade (ICB) antibody such as anti-PD-L1 (aPD-L1) activates cytotoxic T cells (CTLs) to combat cancer, but they showed poor efficacy in prostate cancer (PCa). Lysosome-dependent autophagy is utilized by cancer cells to degrade their MHC-I and to lower their vulnerability to TNF-α and CTLs. Lysosomal pH-sensitive polymeric nanoparticle as a drug delivery carrier may also be a novel autophagy inhibitor to boost immunotherapy, but such an important effect has not been investigated. Herein, we developed a unique tumor acidity-activatable macromolecular nanodrug (called P-PDL1-CP) with the poly(2-diisopropylaminoethyl methacrylate) (PDPA) core and the conjugations of both aPD-L1 and long-chain polyethylene glycol (PEG) coating. The PDPA core was demonstrated to disturb lysosome to block the autophagic flux, thus elevating the cancer cell's MHC-I expression and vulnerability to the TNF-α and CTLs. Long-chain PEG facilitated a good tumor accumulation of P-PDL1-CP nanodrug. Furthermore, P-PDL1-CP nanodrug inhibited tumor autophagy, which synergized with aPD-L1 to promote the tumor-infiltrating CTLs and DCs maturation, to elevate intratumoral TNF-α and IFN-γ levels, and to elicit an anti-tumor immune memory effect in mice for PCa growth inhibition with low side effects. This study verified the synergistic anti-PCa treatment between autophagy inhibition and PD-L1 blockade and meantime broadened the application of pH-sensitive macromolecular nanodrug. STATEMENT OF SIGNIFICANCE: A macromolecular nanodrug, comprising the PDPA core and the surface conjugation of both aPD-L1 antibodies and long-chain PEG coating via a tumor acidity-labile α-carboxy-dimethylmaleic anhydride amine bond, was developed. Tumoral acidity triggered the release of aPD-L1 for immunotherapy. Meantime, the charge switch of the remanent nanodrug enhanced the cancer cell uptake of PDPA, which disturbed the lysosomes to inhibit autophagy. This advanced nanodrug promoted the tumor-infiltrating CTLs and DCs maturation, elevated the intratumoral TNF-α and IFN-γ levels, and elicited the robust anti-tumor immune memory effect. This study demonstrated that the pH-sensitive PDPA macromolecule could serve as a carrier for the aPD-L1 delivery and as an efficient autophagy inhibitor to boost the immunotherapy of prostate cancer.

Tocotrienols: Exciting Biological and Pharmacological Properties of Tocotrienols and Naturally Occurring Compounds, Part II

δ-Tocotrienol plus AHA Step-1 diet in hypercholesterolemic subjects caused reductions in lipid parameters (14% to 18%) with 250 mg/d dose, and 500 mg/d resulted induction in these parameters. Although, α-tocopherol is the most bioavailable form of vitamin E. There are few reports on bioavailability of tocotrienols in humans. Pharmacokinetics and bioavailability of δ-tocotrienol was quantified on plasma levels of tocol isomers, cytokines, and microRNAs. Subjects were fed doses of 125 mg/d to 500 mg/d. Plasma samples collected between 0 h to 10 h, levels of tocols estimated by HPLC, which resulted dose-dependent increases in AUC0-10, Cmax0-∞, Tmaxh, t1/2h, Cl-T 1/h, Vd/f, keh-1. Maximum plasma levels of δ-tocotrienol were at 3 h (125 mg/d to 250 mg/d), 6 h (500 mg/d). Effects of 32 compounds were evaluated on TNF-α secretion, nitric oxide production, and gene expression (TNF-α, IL-1β, IL-6, iNOS activity) in PPAR-α knockout mice. Anticancer activities of thiostrepton, dexamethasone, 2-methoxyestradiol, δ-tocotrienol, quercetin, amiloride, quinine sulfate showed significant anti-proliferative properties in Hela cells, pancreatic, prostate, breast, lungs, melanoma, B-lymphocytes, T-cells (40% to 95%). Results of plasma total mRNAs after δ-tocotrienol feeding to hepatitis C patients revealed significant down-regulated gene expression of pro-inflammatory cytokines. A mixture of δ-tocotrienol, resveratrol, vitamin D3 (NS-3) were given two capsules/d or cellulose/olive oil as placebo to individuals with T2DM (24-weeks). Significant down-regulation (15% to 74%) of gene expression in diabetes biomarkers and decreases i n serum levels of fasting-glucose, HbA1c, hs-CRP, fasting-insulin, HOMA-IR, MDA (9% to 23%) were observed with NS-3 treated T2DM. Pure plasma mRNAs and miRNAs of pre-dose vs. post-dose of NS-3 treated samples were analyzed by Next Generation Sequencing (NGS). Venn diagrams have established genetic regulatory network images and canonical signaling pathways for mRNA, miRNA, and paired mRNA-miRNA.

Combination of the NRF2 Inhibitor and Autophagy Inhibitor Significantly Inhibited Tumorigenicity of Castration-Resistant Prostate Cancer

Prostate cancer (PCa) is the most frequent cancer in men. Developing new treatment methods for CRPC will be a significant challenge in the clinical treatment of PCa. In conclusion, the results of this study show that NRF2 is downregulated in untreated PCa samples compared to normal PCa samples; however, it was upregulated in mCRPC samples compared to HSPC samples. These results demonstrated that NRF2 may serve as a tumor suppressor in tumorigenesis but promote PCa androgen-independent transferring after ADT treatment. Bioinformatics analysis showed that NRF2 was related to multiple signaling, such as the AGE-RAGE pathway, MAPK pathway, NF-kappa B signaling, PI3K-Akt signaling pathway, and VEGF signaling pathway. Moreover, we revealed that the NRF2 inhibitor significantly inhibited tumorigenicity of CRPC cells in vitro. Of note, combination of the NRF2 inhibitor and autophagy inhibitor had a more significantly suppressive role than either ML385 or CQ, indicating that combination of CQ (autophagy inhibitor) and ML385 (NRF2 inhibitor) is a potential treatment of CRPC. Finally, we conformed that high levels of autophagy regulators LC3B, ULK1, and beclin1 significantly correlated to longer PSA recurrence-free survival time. We think that this study could provide more evidence to confirm that NRF2 is a crucial regulator and targeting NRF2 and autophagy is a potential therapy option for CRPC.

STAMP2 suppresses autophagy in prostate cancer cells by modulating the integrated stress response pathway

Six Transmembrane Protein of Prostate 2 (STAMP2) is critical for prostate cancer (PCa) growth. We previously showed that STAMP2 regulates the expression of stress induced transcription factor ATF4, which is implicated in starvation-induced autophagy. We therefore investigated whether STAMP2 is involved in the regulation of autophagy in PCa cells. Here we show that STAMP2 suppresses autophagy in PCa cells through modulation of the integrated stress response axis. We also find that STAMP2 regulates mitochondrial respiration. These findings suggest that STAMP2 has significant metabolic effects through mitochondrial function and autophagy, both of which support PCa growth.

Expression of Autophagy Markers Beclin1 and LC3B in Prostatic Carcinoma: An Immunohistochemical Case-Control Study

BACKGROUND & OBJECTIVE

Prostatic carcinoma represents the second most common cancer diagnosed in men worldwide after lung cancer and the fourth common male malignancy in Egypt. Autophagy is a natural process that has both oncogenic and tumor-suppressive activities. This study aimed to evaluate the role of Beclin1 and LC3B in prostatic carcinoma.

METHODS

This retrospective case-control study was conducted on 110 prostate biopsies divided into three groups (55 prostatic carcinomas, 45 pure benign prostatic hyperplasias (BPH), and 10 BPH with adjacent prostatic carcinoma) retrieved from the archive of the Pathology Department, Faculty of Medicine, Menoufia University, in the period between 2017 and 2020. All biopsies were stained for Beclin1 and LC3B antibodies.

RESULTS

There was a highly significant association between higher Beclin1 and LC3B immunoreactivity score and Gleason score (score 8 and 9) (P=0.002 and 0.000, respectively). Moreover, there was a highly significant direct association between Beclin1 and LC3B expression (r=0.52, P=0.000). Also, there was a significant stepwise increase in Beclin1 positivity among the three studied groups starting from BPH to prostatic carcinoma passing through cases of BPH with neighboring tumor (P=0.000).

CONCLUSION

From the results obtained in the present study, autophagy markers Beclin1 and LC3B showed upregulation in prostatic carcinoma. Moreover, both were associated with poor prognostic factors. So, it might be necessary to control autophagy flux in prostatic carcinoma. This might be one of the future therapeutic targets for the management of prostatic carcinoma.

Quantitative ultrasound shear wave elastography (USWE)-measured tissue stiffness correlates with PIRADS scoring of MRI and Gleason score on whole-mount histopathology of prostate cancer: implications for ultrasound image-guided targeting approach

OBJECTIVE

To correlate quantitative tissue stiffness measurements obtained by transrectal ultrasound shear wave elastography (USWE) with PI-RADS scoring of multiparametric magnetic imaging resonance (mpMRI) using Gleason scores of radical prostatectomy as a reference standard.

PATIENTS AND METHODS

196 men with localised prostate cancer were prospectively recruited into the study and had quantitative prostate tissue stiffness measurements in kilopascals (kPa) using transrectal USWE prior to radical prostatectomy. PI-RADS scores of mpMRI were also obtained in all the men. Imaging and histopathology of radical prostatectomy specimen were oriented to each other using patient specific customised 3D moulds to guide histopathology grossing of radical prostatectomy specimens. All included patients had confirmed PCa on TRUS-guided biopsies, had both USWE and mpMRI imaging data, and underwent radical prostatectomy. Chi-square test with 95% confidence interval was used to assess the difference between Gleason score (GS) of radical prostatectomy and PI-RADS classification, as well as GS of radical prostatectomy and stiffness (in Kpa) using USWE. The correlation coefficient (r) was calculated in order to investigate relation between PI-RADS classification and tissue stiffness in kPa.

RESULTS

There was a statistically significant correlation between USWE-measured tissue stiffness and GS (χ2 (2, N = 196) = 23.577, p < 0.001). Also, there was a statistically significant correlation between Gleason score and PI-RADS score (χ2 (2, N = 196) = 12.838, p = 0.002). High PIRADS on MRI and high stiffness on USWE (> 100 kPa) detected more than 80% and 90% high risk prostate cancer disease. However, a weak correlation coefficient of 0.231 was observed between PI-RADS score and level of tissue stiffness measured in kPa.

CONCLUSION

Quantitative USWE and mpMRI using PI-RADS classification provide a good degree of prediction for Gleason score of clinically significant prostate cancer (csPCa). Stiffer lesions on ultrasound showed a weak correlation with PI-RADS scoring system. USWE could be used to target suspected prostate cancer.

Cytoprotective autophagy induction by withaferin A in prostate cancer cells involves GABARAPL1

Withaferin A (WA) is a naturally occurring steroidal lactone with proven cancer chemopreventive activity in preclinical models of different cancers including prostate adenocarcinoma. Previously we compared the RNA-seq data from control and WA-treated 22Rv1 human prostate cancer cells to identify mechanistic targets of this phytochemical. The Gene Ontology pathway analysis of the RNA-seq data revealed significant upregulation of genes associated with autophagy upon WA treatment in 22Rv1 cells. In this study, we extended these findings to investigate the mechanism underlying WA-induced autophagy. Initially, we confirmed autophagy induction by WA treatment by transmission electron microscopy using three prostate cancer cell lines (LNCaP, 22Rv1, and PC-3). Fourteen common genes altered by 8- and 16-hour exposure to WA were identified from human autophagy PCR array and these results were consistent with the RNA-seq data. Two key autophagy markers (LC3BII and SQSTM1) were robustly increased in WA-exposed LNCaP, 22Rv1, and PC-3 cells as determined by immunoblotting, and this effect was elevated in the presence of autophagy inhibitor bafilomycin A1 (BafA1). BafA1 treatment augmented WA's cytotoxicity and subsequently its proapoptotic potential. WA treatment induced GABARAPL1 (ATG8L) protein expression in all three cell lines and its knockdown by RNA interference attenuated WA-mediated apoptosis. WA-induced autophagy was not affected in the presence of an antioxidant (EUK134). Taken together, the present study reveals that WA-mediated autophagy is cytoprotective and mediated by GABARAPL1.

Divergent Modulation of Proteostasis in Prostate Cancer

Proteostasis regulates key cellular processes such as cell proliferation, differentiation, transcription, and apoptosis. The mechanisms by which proteostasis is regulated are crucial and the deterioration of cellular proteostasis has been significantly associated with tumorigenesis since it specifically targets key oncoproteins and tumor suppressors. Prostate cancer (PCa) is the second most common cause of cancer death in men worldwide. Androgens mediate one of the most central signaling pathways in all stages of PCa via the androgen receptor (AR). In addition to their regulation by hormones, PCa cells are also known to be highly secretory and are particularly prone to ER stress as proper ER function is essential. Alterations in various complex signaling pathways and cellular processes including cell cycle control, transcription, DNA repair, apoptosis, cell adhesion, epithelial-mesenchymal transition (EMT), and angiogenesis are critical factors influencing PCa development through key molecular changes mainly by posttranslational modifications in PCa-related proteins, including AR, NKX3.1, PTEN, p53, cyclin D1, and p27. Several ubiquitin ligases like MDM2, Siah2, RNF6, CHIP, and substrate-binding adaptor SPOP; deubiquitinases such as USP7, USP10, USP26, and USP12 are just some of the modifiers involved in the regulation of these key proteins via ubiquitin-proteasome system (UPS). Some ubiquitin-like modifiers, especially SUMOs, have been also closely associated with PCa. On the other hand, the proteotoxicity resulting from misfolded proteins and failure of ER adaptive capacity induce unfolded protein response (UPR) that is an indispensable signaling mechanism for PCa development. Lastly, ER-associated degradation (ERAD) also plays a crucial role in prostate tumorigenesis. In this section, the relationship between prostate cancer and proteostasis will be discussed in terms of UPS, UPR, SUMOylation, ERAD, and autophagy.

Ophiopogonin D' induces RIPK1‑dependent necroptosis in androgen‑dependent LNCaP prostate cancer cells

Ophiopogonin D' (OPD') is a natural compound extracted from Ophiopogon japonicus, which is a plant used in traditional Chinese medicine. Our previous study has indicated that OPD' exhibits antitumor activity against androgen-independent prostate cancer (PCa), but the effects and the underlying molecular mechanism of action of OPD' in androgen-dependent PCa were unclear. In the present study, OPD' induced significant necroptosis in androgen-dependent LNCaP cancer cells by activating receptor-interacting serine/threonine-protein kinase 1 (RIPK1). Exposure to OPD' also increased Fas ligand (FasL)-dependent RIPK1 protein expression. The OPD'-induced necroptosis was inhibited by a RIPK1 inhibitor necrostatin-1, further supporting a role for RIPK1 in the effects of OPD´. The antitumor effects of OPD' were also inhibited by a mixed lineage kinase domain-like protein (MLKL) inhibitor necrosulfonamide. Following treatment with inhibitors of RIPK1 and MLKL, the effects of OPD' on LNCaP cells were inhibited in an additive manner. In addition, co-immunoprecipitation assays demonstrated that OPD' induced RIPK3 upregulation, leading to the assembly of a RIPK3-MLKL complex, which was independent of RIPK1. Furthermore, OPD' increased the expression of Fas-associated death domain, which is required to induce necroptosis in LNCaP cells. OPD' also regulated the expression levels of FasL, androgen receptor and prostate-specific antigen in a RIPK1-dependent manner. These results suggested that OPD' may exhibit potential as an anti-PCa agent by inducing RIPK1- and MLKL-dependent necroptosis.

Identification of aberrantly methylated differentially expressed genes in prostate carcinoma using integrated bioinformatics

Background

Methylation plays a key role in the aetiology and pathogenesis of prostate cancer (PCa). This study aimed to identify aberrantly methylated differentially expressed genes (DEGs) and pathways in PCa and explore the underlying mechanisms of tumourigenesis.

Methods

Expression profile (GSE29079) and methylation profile (GSE76938) datasets were obtained from the Gene Expression Omnibus (GEO). We used R 3.4.4 software to assess aberrantly methylated DEGs. The Cancer Genome Atlas (TCGA) RNA sequencing and Illumina HumanMethylation450 DNA methylation data were utilized to validate screened genes. Functional enrichment analysis of the screened genes was performed, and a protein–protein interaction (PPI) network was constructed using the Search Tool for the Retrieval of Interacting Gens (STRING). The results were visualized in Cytoscape. After confirmation using TCGA, cBioPortal was used to examine alterations in genes of interest. Then, protein localization in PCa cells was observed using immunohistochemistry.

Results

Overall, 536 hypomethylated upregulated genes were identified that were enriched in biological processes such as negative regulation of transcription, osteoblast differentiation, intracellular signal transduction, and the Wnt signalling pathway. Pathway enrichment showed significant changes in factors involved in AMPK signalling, cancer, and adherens junction pathways. The hub oncogenes were AKT1, PRDM10, and FASN. Additionally, 322 hypermethylated downregulated genes were identified that demonstrated enrichment in biological processes including positive regulation of the MAPK cascade, muscle contraction, ageing, and signal transduction. Pathway analysis indicated enrichment in arrhythmogenic right ventricular cardiomyopathy (ARVC), focal adhesion, dilated cardiomyopathy, and PI3K-AKT signalling. The hub tumour suppressor gene was FLNA. Immunohistochemistry showed that AKT1, FASN, and FLNA were mainly expressed in PCa cell cytoplasm, while PRDM10 was mainly expressed in nuclei.

Conclusions

Our results identify numerous novel genetic and epigenetic regulatory networks and offer molecular evidence crucial to understanding the pathogenesis of PCa. Aberrantly methylated hub genes, including AKT1, PRDM10, FASN, and FLNA, can be used as biomarkers for accurate PCa diagnosis and treatment. In conclusion, our study suggests that AKT1, PRDM10, and FASN may be tumour promoters and that FLNA may be a tumour suppressor in PCa. We hope these findings will draw more attention to these hub genes in future cancer studies.

Reversibility of castration resistance status after Radium-223 dichloride treatment: clinical evidence and review of the literature

In the history of prostate cancer, some of the patients progressed to castration-resistant prostate cancer (CRPC) stage and, although new drugs and treatment protocols have been introduced, CRPC presents poor prognosis. This review is focused on biological mechanisms, underlying CRPC described in scientific literature in order to explain the reversion of resistance to castration. We present the case of a 73-year-old man, affected by bone metastatic CRPC, early treated with Radium-223 with a complete response. After 15 months from Radium-223 treatment, prostate-specific antigen increased with radiological progression. Androgen deprivation therapy was again performed and was effective, despite previous CRPC condition and no known mechanisms that may explain the reversion of this condition. Therefore, to our knowledge, he is the unique described case of the reversion of resistance to castration. Nevertheless, promising aspects may be lack of intrametastatic production of androgen or the suppression of bypass androgen receptor signaling pathways. Furthermore, the cytotoxic action of Radium-223 on cancer stem cell (CSC), due to surrounding clones with high-bone turnover, or the immune response that underlying the abscopal effect, may also modulate the reversion of CRPC after Radium-223. If confirmed by multicenter trials, the reversion of CRPC may impact on the management of prostate cancer.

Prostate Cancer Energetics and Biosynthesis

Cancers must alter their metabolism to satisfy the increased demand for energy and to produce building blocks that are required to create a rapidly growing tumor. Further, for cancer cells to thrive, they must also adapt to an often changing tumor microenvironment, which can present new metabolic challenges (ex. hypoxia) that are unfavorable for most other cells. As such, altered metabolism is now considered an emerging hallmark of cancer. Like many other malignancies, the metabolism of prostate cancer is considerably different compared to matched benign tissue. However, prostate cancers exhibit distinct metabolic characteristics that set them apart from many other tumor types. In this chapter, we will describe the known alterations in prostate cancer metabolism that occur during initial tumorigenesis and throughout disease progression. In addition, we will highlight upstream regulators that control these metabolic changes. Finally, we will discuss how this new knowledge is being leveraged to improve patient care through the development of novel biomarkers and metabolically targeted therapies.

Association of Autophagy Gene ATG16L1 Polymorphism with Human Prostate Cancer and Bladder Cancer in Turkish Population

Background: Urological cancers (prostate cancer and bladder cancers) are the most common cancers in Western population and its rate is increasing in the Eastern World. Autophagy has appeared as a fundamental repair mechanism for degrading damaged organelles and proteins. It was clear that autophagy gene polymorphisms are correlated with development of inflammatory bowel disease and it can also be related with prostate cancer (PCa) or bladder cancer (BCa). In this study, we aimed to determine if ATG16L1 (Thr300Ala) polymorphism is associated with an increased risk of developing PCa and BCa and to establish correlations between ATG16L1 genotypes and morphological parameters. Methods: This study included 269 healthy controls and 131 patients (62 PCa and 69 BCa) with PCa and BCa. The ATG16L1 (rs2241880) gene regions were amplified using polymerase chain reaction (PCR), detected by restriction fragment length polymorphism (RFLP). Results: At the end of our research, we found out that the genotype AG was prevalent on patients and controls (34% vs 42%), followed by genotypes AA (35% vs 27%) and GG (31% vs 31%) in PCa. The prevalence of genotypes of AA (wild-type), AG (heterozygous mutant) and GG (homozygous mutant) profiles for the ATG16L1 Thr300Ala polymorphism were 35%, 40% and 25% respectively in BCa patients, and 32%, 40% and 28% respectively in healthy control groups. The G allele frequency was 0.53 for in BCa patients and the control groups. Conclusion: No association was found between ATG16L1 (Thr300Ala) polymorphism and patients with PCa and BCa in Turkish population we studied.

Endothelial cells promote metastasis of prostate cancer by enhancing autophagy

BACKGROUND

Prostate cancer is one of the most common malignancies. Increasing evidence suggested that endothelial cells may contribute to prostate cancer progression and metastasis. Most recently, autophagy has been proposed to plays a significant role in tumorigenesis and metastasis. Also, it is reported that downregulation of androgen receptor (AR) induces autophagy in prostate cancer cells. However, the underlying mechanisms remain unclear. Here, we aim to explore the role and mechanisms of endothelial cell in prostate cancer progression.

METHODS

The coculture system was established to test the effect of endothelial cells on prostate cancer cells. We performed antibody array and ELISA were used to profile the cytokine expression pattern of endothelial cells in supernatant. Western blot and RT-PCR were used to determine the mechanism by endothelial cells to promote invasion ability of prostate cancer cells. Maraviroc and chloroquine were used to block the CCL5/CCR5 and autophagy pathway respectively. Orthotopic xenograft mouse models and drug treatment study were conducted to determine the role of endothelial cells in promoting metastatic potential in vivo.

RESULTS

We use CPRC prostate cancer model and demonstrate that endothelial cells secrete large amount of CCL5 and induces autophagy by suppressing AR expression in prostate cancer cell lines. Consequently, elevated autophagy accelerates focal adhesions proteins disassembly and promoted prostate cancer invasion. Inhibition of both CCL5/CCR5 signaling and autophagy significantly reduces metastasis in vivo.

CONCLUSIONS

Together, our data establish the function for endothelial cells in tumor metastasis and propose new drug target for mCRPC.

δ-Tocotrienol feeding modulates gene expression of EIF2, mTOR, protein ubiquitination through multiple-signaling pathways in chronic hepatitis C patients

Background

δ-Tocotrienol is a naturally occurring proteasome inhibitor, which has the capacity to inhibit proliferation and induce apoptosis in several cancer cells obtained from several organs of humans, and other cancer cell lines. Moreover, results of plasma total mRNAs after δ-tocotrienol feeding to hepatitis C patients revealed significant inhibition in the expression of pro-inflammatory cytokines (TNF-α, VCAM1, proteasome subunits) and induction in the expression of ICAM1 and IFN-γ after post-treatment. This down-regulation of proteasome subunits leads to autophagy, apoptosis of immune cells and several genes. The present study describes RNA-sequence analysis of plasma total mRNAs obtained from δ-tocotrienol treatment of hepatitis C patients on gene expression regulated by proteasome.

Methods

Pooled specimens of plasma total mRNAs of pre-dose versus post-dose of δ-tocotrienol treatment of hepatitis C patients were submitted to RNA-sequence analyses. The data based on > 1 and 8-fold expression changes of 2136 genes were uploaded into “Ingenuity Pathway Analyses (IPA)” for core analysis, which describes possible canonical pathways, upstream regulators, diseases and functional metabolic networks.

Results

The IPA of “molecules” indicated fold change in gene expression of 953 molecules, which covered several categories of biological biomarkers. Out of these, gene expression of 220 related to present study, 12 were up-regulated, and 208 down-regulated after δ-tocotrienol treatment. The gene expression of transcription regulators (ceramide synthase 3 and Mohawk homeobox) were up-regulated, and gene expression of 208 molecules were down-regulated, involved in several biological functions (HSP90AB1, PSMC3, CYB5R4, NDUFB1, CYP2R1, TNFRF1B, VEGFA, GPR65, PIAS1, SFPQ, GPS2, EIF3F, GTPBP8, EIF4A1, HSPA14, TLR8, TUSSC2). IPA of “causal network” indicated gene regulators (676), in which 76 down-regulated (26 s proteasomes, interleukin cytokines, and PPAR-ligand-PPA-Retinoic acid-RXRα, PPARγ-ligand-PPARγ-Retinoic acid-RARα, IL-21, IL-23) with significant P-values. The IPA of “diseases and functions” regulators (85) were involved with cAMP, STAT2, 26S proteasome, CSF1, IFNγ, LDL, TGFA, and microRNA-155-5p, miR-223, miR-21-5p. The IPA of “upstream analysis” (934) showed 57 up-regulated (mainly 38 microRNAs) and 64 gene regulators were down-regulated (IL-2, IL-5, IL-6, IL-12, IL-13, IL-15, IL-17, IL-18, IL-21, IL-24, IL-27, IL-32), interferon β-1a, interferon γ, TNF-α, STAT2, NOX1, prostaglandin J2, NF-κB, 1κB, TCF3, and also miRNA-15, miRNA-124, miRNA-218-5P with significant activation of Z-Score (P < 0.05).

Conclusions

This is first report describing RNA-sequence analysis of δ-tocotrienol treated plasma total mRNAs obtained from chronic hepatitis C patients, that acts via multiple-signaling pathways without any side-effects. These studies may lead to development of novel classes of drugs for treatment of chronic hepatitis C patients.

Electronic supplementary material

The online version of this article (10.1186/s12944-018-0804-7) contains supplementary material, which is available to authorized users.

Qianlie Xiaozheng Decoction Induces Autophagy in Human Prostate Cancer Cells via Inhibition of the Akt/mTOR Pathway

Qianlie Xiaozheng decoction (QLXZD), a traditional Chinese medicinal formula, has been used clinically to treat advanced prostate cancer (PCa) for more than 10 years. However, experimental evidence supporting its efficacy is lacking. Here, we investigated the anticancer properties and molecular mechanism of QLXZD in vitro in a human PCa cell line (PC3) and in vivo using PC3 xenografts in nude mice. We confirmed the antineoplastic activity of QLXZD by analyzing cell viability and tumor volume growth, which decreased significantly compared to that of the controls. Autophagy following QLXZD treatment was detected morphologically using transmission electron microscopy and was confirmed by measuring the expression of autophagy markers (LC3-II and p62) using fluorescence analysis, flow cytometry, and western blotting. Increasing autophagic flux induced by QLXZD was monitored via pmCherry-GFP-LC3 fluorescence analysis. QLXZD-induced autophagic cell death was alleviated by the autophagy inhibitors, 3-methyl adenine and hydroxychloroquine. We evaluated the total expression and phosphorylation levels of proteins involved in the Akt/mTOR pathway regulating autophagy. Phosphorylation of Akt, mTOR, and p70S6K, but not total protein levels, decreased following treatment. This is the first study to demonstrate the autophagy-related mechanistic pathways utilized during QLXZD-mediated antitumor activity both in vitro and in vivo. These findings support the clinical use of QLXZD for PCa treatment.

Proteasome inhibitors modulate anticancer and anti-proliferative properties via NF-kB signaling, and ubiquitin-proteasome pathways in cancer cell lines of different organs

BACKGROUND

Cancer is second most common cause of death in the United State. There are over 100 different types of cancer associated with different human organs, predominantly breast, liver, pancreas, prostate, colon, rectum, lung, and stomach. We have recently reported properties of pro-inflammatory (for treatment of various types of cancers), and anti-inflammatory (for cardiovascular disease and diabetes) compounds. The major problem associated with development of anticancer drugs is their lack of solubility in aqueous solutions and severe side effects in cancer patients. Therefore, the present study was carried out to check anticancer properties of selected compounds, mostly aqueous soluble, in cancer cell lines from different organs.

METHODS

The anticancer properties, anti-proliferative, and pro-apoptotic activity of novel naturally occurring or FDA approved, nontoxic, proteasome inhibitors/activators were compared. In addition to that, effect of δ-tocotrienol on expression of proteasome subunits (X, Y, Z, LMP7, LMP2, LMP10), ICAM-1, VCAM-1, and TNF-α using total RNAs derived from plasmas of hepatitis C patients was investigated.

RESULTS

Our data demonstrated that following compounds are very effective in inducing apoptosis of cancer cells: Thiostrepton, dexamethasone, 2-methoxyestradiol, δ-tocotrienol, quercetin, amiloride, and quinine sulfate have significant anti-proliferation properties in Hela cells (44% - 87%) with doses of 2.5-20 μM, compared to respective controls. Anti-proliferation properties of thiostrepton, 2-methoxyestradiol, δ-tocotrienol, and quercetin were 70% - 92%. However, thiostrepton, dexamethasone, 2-methoxyestradiol, δ-tocotrienol, quercetin, and quinine sulphate were effective in pancreatic, prostate, breast, lungs, melanoma, Β-lymphocytes, and T-cells (Jurkat: 40% to 95%) compared to respective controls. In lung cancer cells, these compounds were effective between 5 and 40 μM. The IC₅₀ values of anti-proliferation properties of thiostrepton in most of these cell lines were between doses of 2.5-5 μM, dexamethasone 2.5-20 μM, 2-methoxyestradiol 2.5-10 μM, δ-tocotrienol 2.5-20 μM, quercetin 10-40 μM, and (-) Corey lactone 40-80 μM. In hepatitis C patients, δ-tocotrienol treatment resulted in significant decrease in the expression of pro-inflammatory cytokines.

CONCLUSIONS

These data demonstrate effectiveness of several natural-occurring compounds with anti-proliferative properties against cancer cells of several organs of humans. Thiostrepton, dexamethasone, 2-methoxyestradiol, δ-tocotrienol and quercetin are very effective for apoptosis of cancer cells in liver, pancreas, prostate, breast, lung, melanoma, Β-lymphocytes and T-cells. The results have provided an opportunity to test these compounds either individually or in combination as dietary supplements in humans for treatment of various types of cancers.

p62 as a therapeutic target for inhibition of autophagy in prostate cancer

BACKGROUND

To test the hypothesis that p62 is an optimal target for autophagy inhibition and Verteporfin, a clinically available drug approved by FDA to treat macular degeneration that inhibits autophagy by targeting p62 protein, can be developed clinically to improve therapy for advanced prostate cancer.

METHODS

Forced expression of p62 in PC-3 cells and normal prostate epithelial cells, RWPE-1 and PZ-HPV7, were carried out by transfection of these cells with pcDNA3.1/p62 or p62 shRNA plasmid. Autophagosomes and autophagic flux were measured by transfection of tandem fluorescence protein mCherry-GFP-LC3 construct. Apoptosis was measured by Annexin V/PI staining. Tumorigenesis was measured by a xenograft tumor growth model.

RESULTS

Verteporfin inhibited cell growth and colony formation in PC-3 cells. Verteporfin generated crosslinked p62 oligomers, resulting in inhibition of autophagy and constitutive activation of Nrf2 as well as its target genes, Bcl-2 and TNF-α. In normal prostate epithelial cells, forced expression of p62 caused constitutive Nrf2 activation, development of apoptosis resistance, and Verteporfin treatment exhibited inhibitory effects. Verteporfin treatment also inhibited starvation-induced autophagic flux of these cells. Verteporfin inhibited tumorigenesis of both normal prostate epithelial cells with p62 expression and prostate cancer cells and decreased p62, constitutive Nrf2, and Bcl-xL in xenograft tumor tissues, indicating that p62 can be developed as a drug target against prostate cancer.

CONCLUSIONS

p62 has a high potential to be developed as a therapeutic target. Verteporfin represents a prototypical agent with therapeutic potential against prostate cancer through inhibition of autophagy by a novel mechanism of p62 inhibition.

Negative LC3b immunoreactivity in cancer cells is an independent prognostic predictor of prostate cancer specific death

Background

Autophagy is a catabolic cellular process used for degradation of cytoplasmic organelles and preservation of cell viability. In this study we aimed to analyse the level of autophagy markers in benign and malignant prostate tissue and to evaluate the prognostic properties for patients with prostate cancer (PCa).

Results

LC3b expression was significantly upregulated in PCa, especially in metastatic and castration-resistant PCa samples compared to benign prostate tissue (p<0.001). Evaluation of expression in malignant radical prostatectomy specimens revealed an inverse association with preoperative serum PSA levels (p=0.02) and Gleason Score (p=0.07). LC3b immunoreactivity was identified as a novel predictor of PCa specific death after radical prostatectomy, independent of Gleason score, tumour stage, and surgical margin status in a multivariable cox regression analysis (hazard ratio 0.09, 95% confidence interval 0.01-0.69, p=0.021). A significant association of ATG-5 and Beclin 1 with LC3b expression could be noticed (p<0.001), but no link with other clincopathologic parameters was observed.

Materials and Methods

A Tissue microarray containing 468 formalin-fixed, paraffin-embedded prostate tissue cores was stained immunohistochemically for major autophagy proteins LC3b, ATG5 and Beclin 1. Immunoreactivity was semiquantitatively scored and correlated with pathologic and clinical parameters, including tumour stage, Gleason score, preoperative PSA level, biochemical recurrence rate and survival. The median clinical follow-up was 132 months.

Conclusion

LC3b was significantly overexpressed in malignant compared to benign prostate tissue. However, positive LC3b immunoreactivity in PCa, as a marker of increased autophagy, was independently associated with a reduced disease-specific mortality.

Molecular and cellular mechanisms of castration resistant prostate cancer

With increases in the mortality rate and number of patients with prostate cancer (PCa), PCa, particularly the advanced and metastatic disease, has been the focus of a number of studies globally. Over the past seven decades, androgen deprivation therapy has been the primary therapeutic option for patients with advanced PCa; however, the majority of patients developed a poor prognosis stage of castration resistant prostate cancer (CRPC), which eventually led to mortality. Due to CRPC being incurable, laboratory investigations and clinical studies focusing on CRPC have been conducted worldwide. Clarification of the molecular pathways that may lead to CRPC is important for discovering novel therapeutic strategies to delay or reverse the progression of disease. A sustained androgen receptor (AR) signal is still regarded as the main cause of CRPC. Increasing number of studies have proposed different potential mechanisms that cause CRPC, and this has led to the development of novel agents targeting the AR-dependent pathway or AR-independent signaling. In the present review, the major underlying mechanisms causing CRPC, including several major categories of AR-dependent mechanisms, AR bypass signaling, AR-independent mechanisms and other important hypotheses (including the functions of autophagy, PCa stem cell and microRNAs in CRPC progression), are summarized with retrospective pre-clinical or clinical trials to guide future research and therapy.

Roles of autophagy in androgen-induced benign prostatic hyperplasia in castrated rats

The present study investigated the role of androgen in the process of androgen-induced prostate hyperplasia in castrated rats and assessed the role of the phosphoinositide 3-kinase/protein kinase B/mechanistic target of rapamycin (PI3K/Akt/mTOR) pathway in this process. Furthermore, the extent to which autophagy may affect the level of androgen-induced benign prostatic hyperplasia was also explored. A total of 40 Sprague Dawley rats were randomly divided into four groups: Testosterone group, rapamycin group, 3-methyladenine (3-MA) group, and control group. The extent of hyperplasia in prostate tissue the apoptosis and autophagy were assayed. The prostate wet weight, volume and index in the testosterone group were significantly higher compared with the control group (P<0.05) and these factors were significantly lower in the rapamycin group compared with the testosterone group (P<0.05). HE staining demonstrated that prostate hyperplasia was obvious in the testosterone group. Western blotting revealed that caspase-3 levels were higher in the 3-MA group compared with the control group and Bcl-2 was higher in the testosterone group compared with the control group (P<0.05). Furthermore, in the rapamycin group, Bcl-2 protein expression levels were significantly lower than those in the testosterone group (P<0.05). The prostate tissue was analyzed using electron microscopy and autophagy bodies were identified in the rapamycin group. In the process of androgen-induced prostatic hyperplasia in castrated rats, the role of androgen may be related to the PI3K/Akt/mTOR signaling pathway. Rapamycin was able to inhibit the effect of testosterone and promoted prostate tissue hyperplasia by inhibiting the PI3K/Akt pathway. In addition to inhibiting apoptosis in prostate cells, androgen was able to induce rat prostate hyperplasia and may also be related to the promotion of the proliferation of prostate cells.

Sensitisation to mitoxantrone-induced apoptosis by the oncolytic adenovirus Ad∆∆ through Bcl-2-dependent attenuation of autophagy

Anti-apoptotic Bcl-2 is frequently activated in human malignant cells to promote cell survival and inhibit cell death. Replication-selective oncolytic adenoviruses deleted in the functional Bcl-2 homologue E1B19K potently synergise with apoptosis-inducing chemotherapeutic drugs, including mitoxantrone for prostate cancer. Here, we demonstrate that our previously generated oncolytic mutant Ad∆∆ (E1B19K- and E1ACR2-deleted) caused potent synergistic apoptotic cell death in both drug-sensitive 22Rv1, and drug-insensitive PC3 and PC3M prostate cancer cells. The synergistic cell killing was dependent on Bcl-2 expression and was prevented by Bcl-2 knockdown, which led to activation of the autophagy pathway. Mitoxantrone-induced autophagy, which was decreased in combination with Ad∆∆-infection resulting in increased apoptosis. Expression of the viral E1A12S protein alone mimicked the synergistic effects with Ad∆∆ in combination with mitoxantrone while intact wild-type virus (Ad5) had no effect. Early and late-stage inhibition of autophagy by Atg7 knockdown and chloroquine respectively, promoted apoptotic cell killing with mitoxantrone similar to Ad∆∆. These findings revealed currently unexplored actions of E1B19K-deleted oncolytic adenoviruses and the central role of Bcl-2 in the synergistic cell killing. This study suggests that cancers with functional Bcl-2 expression may be selectively re-sensitised to drugs by Ad∆∆.

Multifaceted Roles of GSK-3 in Cancer and Autophagy-Related Diseases

GSK-3 is a ubiquitously expressed serine/threonine kinase existing as GSK-3α and GSK-3β isoforms, both active under basal conditions and inactivated upon phosphorylation by different upstream kinases. Initially discovered as a regulator of glycogen synthesis, GSK-3 is also involved in several signaling pathways controlling many different key functions. Here, we discuss recent advances regarding (i) GSK-3 structure, function, regulation, and involvement in several cancers, including hepatocarcinoma, cholangiocarcinoma, breast cancer, prostate cancer, leukemia, and melanoma (active GSK-3 has been shown to induce apoptosis in some cases or inhibit apoptosis in other cases and to induce cancer progression or inhibit tumor cell proliferation, suggesting that different GSK-3 modulators may address different specific targets); (ii) GSK-3 involvement in autophagy modulation, reviewing signaling pathways involved in neurodegenerative and liver diseases; (iii) GSK-3 role in oxidative stress and autophagic cell death, focusing on liver injury; (iv) GSK-3 as a possible therapeutic target of natural substances and synthetic inhibitors in many diseases; and (v) GSK-3 role as modulator of mammalian aging, related to metabolic alterations characterizing senescent cells and age-related diseases. Studies summarized here underline the GSK-3 multifaceted role and indicate such kinase as a molecular target in different pathologies, including diseases associated with autophagy dysregulation.

Up-regulation of autophagy is a mechanism of resistance to chemotherapy and can be inhibited by pantoprazole to increase drug sensitivity

BACKGROUND

Autophagy is a survival mechanism that allows recycling of cellular breakdown products, particularly in stressed cells. Here we evaluate the hypotheses that up-regulation of autophagy is a common mechanism of resistance to chemotherapy, and that drug resistance can be reversed by inhibiting autophagy with a proton pump inhibitor.

METHODS

We exposed human PC3, LNCaP and MCF7 cells to seven clinically-used chemotherapy drugs ± pantoprazole, examined the up-regulation of autophagy and the effect on cellular proliferation by Western Blots, MTS assay and colony-forming assay. The distribution of drug effects and of autophagy was quantified in LNCaP tumor sections in relation to blood vessels and hypoxia by immunohistochemistry using γH2AX, cleaved caspase-3 and p62.

RESULTS

All anticancer drugs led to up-regulation of autophagy in cultured tumor cells. Pantoprazole inhibited the induction of autophagy in a time- and dose-dependent manner, and sensitized cancer cells to the seven anti-cancer drugs. Treatment of LNCaP xenografts with paclitaxel induced both DNA damage and autophagy; autophagy was inhibited and markers of toxicity were increased by pantoprazole.

CONCLUSIONS

Induction of autophagy is a general mechanism associated with resistance to anticancer drugs and that its inhibition is a promising therapeutic strategy to enhance the effects of chemotherapy and improve clinical outcomes.

Autophagy activated by the c-Jun N-terminal kinase-mediated pathway protects human prostate cancer PC3 cells from celecoxib-induced apoptosis

The aim of the present study was to investigate the role of autophagy in celecoxib-induced apoptosis in human hormone-insensitive prostate cancer cell line PC3 cells and to explore the underlying molecular mechanism leading to autophagic activation. A cell viability assay was applied to investigate the effect of various concentrations of celecoxib (0, 40, 60, 80, 100 and 120 µmol/l) on PC3 cells for 24 and 48 h, respectively. The 50% inhibitory concentration of celecoxib for 24 h was chosen for subsequent experiments. Annexin V-fluorescein isothiocyanate/propidium iodide double staining flow cytometry, as well as caspase 3 and poly (ADP-ribose) polymerase proteins detected by western blotting, were applied to analyze cellular apoptosis induced by celecoxib. Ultrastructural cellular changes observed by transmission electron microscopy and the level of LC-3 II and P62 detected by western blotting were used to determine the activation of autophagy. It was demonstrated that celecoxib induced apoptosis and activated autophagy in PC3 cells in a dose- and time-dependent manner. Furthermore, flow cytometry and western blotting were applied to elucidate whether the role of autophagy in celecoxib-induced apoptosis is protective or destructive. Blockade of autophagy markedly increased apoptosis, suggesting that celecoxib-activated autophagy was cytoprotective. Additionally, c-jun-N-terminal kinase (JNK) was demonstrated to have a role in autophagic activation, and suppression of JNK was able to reduce autophagy and increase apoptosis. In conclusion, the results of the present study indicate that celecoxib induces apoptosis in PC3 cells; however, celecoxib also activates JNK-mediated autophagy, which exerts cytoprotective effects in prostate cancer PC3 cells. Blockade of autophagy via the JNK-mediated pathway may provide a promising strategy for prostate cancer therapy.

Reciprocal Crosstalk Between Autophagic and Endocrine Signaling in Metabolic Homeostasis

Autophagy is a cellular quality control and energy-providing process that is under strict control by intra- and extracellular stimuli. Recently, there has been an exponential increase in autophagy research and its implications for mammalian physiology. Autophagy deregulation is now being implicated in many human diseases, and its modulation has shown promising results in several preclinical studies. However, despite the initial discovery of autophagy as a hormone-regulated process by De Duve in the early 1960s, endocrine regulation of autophagy still remains poorly understood. In this review, we provide a critical summary of our present understanding of the basic mechanism of autophagy, its regulation by endocrine hormones, and its contribution to endocrine and metabolic homeostasis under physiological and pathological settings. Understanding the cross-regulation of hormones and autophagy on endocrine cell signaling and function will provide new insight into mammalian physiology as well as promote the development of new therapeutic strategies involving modulation of autophagy in endocrine and metabolic disorders.

p62/SQSTM1-Dr. Jekyll and Mr. Hyde that prevents oxidative stress but promotes liver cancer

p62/SQSTM1 is a multifunctional signaling hub and autophagy adaptor with many binding partners, which allow it to activate mTORC1-dependent nutrient sensing, NF-κB-mediated inflammatory responses, and the NRF2-activated antioxidant defense. p62 recognizes polyubiquitin chains via its C-terminal domain and binds to LC3 via its LIR motif, thereby promoting the autophagic degradation of ubiquitinated cargos. p62 accumulates in many human liver diseases, including nonalcoholic steatohepatitis (NASH) and hepatocellular carcinoma (HCC), where it is a component of Mallory-Denk bodies and intracellular hyaline bodies. Chronic p62 elevation contributes to HCC development by preventing oncogene-induced senescence and death of cancer-initiating cells and enhancing their proliferation. In this review, we discuss p62-mediated signaling pathways and their roles in liver pathophysiology, especially NASH and HCC.

Broad targeting of resistance to apoptosis in cancer

Apoptosis or programmed cell death is natural way of removing aged cells from the body. Most of the anti-cancer therapies trigger apoptosis induction and related cell death networks to eliminate malignant cells. However, in cancer, de-regulated apoptotic signaling, particularly the activation of an anti-apoptotic systems, allows cancer cells to escape this program leading to uncontrolled proliferation resulting in tumor survival, therapeutic resistance and recurrence of cancer. This resistance is a complicated phenomenon that emanates from the interactions of various molecules and signaling pathways. In this comprehensive review we discuss the various factors contributing to apoptosis resistance in cancers. The key resistance targets that are discussed include (1) Bcl-2 and Mcl-1 proteins; (2) autophagy processes; (3) necrosis and necroptosis; (4) heat shock protein signaling; (5) the proteasome pathway; (6) epigenetic mechanisms; and (7) aberrant nuclear export signaling. The shortcomings of current therapeutic modalities are highlighted and a broad spectrum strategy using approaches including (a) gossypol; (b) epigallocatechin-3-gallate; (c) UMI-77 (d) triptolide and (e) selinexor that can be used to overcome cell death resistance is presented. This review provides a roadmap for the design of successful anti-cancer strategies that overcome resistance to apoptosis for better therapeutic outcome in patients with cancer.

Targeting autophagy for therapy of gastric cancer

Gastric cancer is one of the most common malignant neoplasms. Surgery represents the main approach for this disease. Notwithstanding the advances in surgical techniques, there has been still a minimal improvement in overall survival with a significant increase in relapse rates. Although the development of new drugs has significantly improved the effectiveness of chemotherapy, the prognosis of patients with unresectable or metastatic gastric carcinoma remains poor. Therefore, it is necessary to find some new ways against gastric carcinogenesis. It has been shown that autophagy plays a dual role in the transformation and progression of gastric cancer; activation and induction of autophagy can lead to gastric carcinogenesis. Recently, several agents targeting autophagy molecules in gastric carcinogenesis have been investigated. This article reviews the regulation of autophagy with inhibitors or inducers to treat gastric cancer, and discusses how they regulate autophagy as a targeted therapy for gastric cancer.

Autophagy as a modulator and target in prostate cancer

Autophagy, or 'self-eating', is an adaptive process that enables cells to cope with metabolic, toxic, and even infectious stressors. Although the adaptive capability of autophagy is generally considered beneficial, autophagy can also enhance nutrient utilization and improve growth characteristics of cancer cells. Moreover, autophagy can promote greater cellular robustness in the context of therapeutic intervention. In advanced prostate cancer, preclinical data provide evidence that autophagy facilitates both disease progression and therapeutic resistance. Notably, androgen deprivation therapy, taxane-based chemotherapy, targeted kinase inhibition, and nutrient restriction all induce significant cellular distress and, subsequently, autophagy. Understanding the context-dependent role of autophagy in cancer development and treatment resistance has the potential to improve current treatment of advanced prostate cancer. Indeed, preclinical studies have shown that the pharmacological inhibition of autophagy (with agents including chloroquine, hydroxychloroquine, metformin, and desmethylclomipramine) can enhance the cell-killing effect of cancer therapeutics, and a number of these agents are currently under investigation in clinical trials. However, many of these autophagy modulators are relatively nonspecific, and cytotoxicity in noncancerous tissues is still a concern. Moving forward, refinement of autophagy modulation is needed.

Autophagic flux determines cell death and survival in response to Apo2L/TRAIL (dulanermin)

Background

Macroautophagy is a catabolic process that can mediate cell death or survival. Apo2 ligand (Apo2L)/tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) treatment (TR) is known to induce autophagy. Here we investigated whether SQSTM1/p62 (p62) overexpression, as a marker of autophagic flux, was related to aggressiveness of human prostate cancer (PCa) and whether autophagy regulated the treatment response in sensitive but not resistant PCa cell lines.

Methods

Immunostaining and immunoblotting analyses of the autophagic markers p62 [in PCa tissue microarrays (TMAs) and PCa cell lines] and LC3 (in PCa cell lines), transmission electron microscopy, and GFP-mCherry-LC3 were used to study autophagy induction and flux. The effect of autophagy inhibition using pharmacologic (3-methyladenine and chloroquine) and genetic [(short hairpin (sh)-mediated knock-down of ATG7 and LAMP2) and small interfering (si)RNA-mediated BECN1 knock-down] approaches on TR-induced cell death was assessed by clonogenic survival, sub-G1 DNA content, and annexinV/PI staining by flow cytometry. Caspase-8 activation was determined by immunoblotting.

Results

We found that increased cytoplasmic expression of p62 was associated with high-grade PCa, indicating that autophagy signaling might be important for survival in high-grade tumors. TR-resistant cells exhibited high autophagic flux, with more efficient clearance of p62-aggregates in four TR-resistant PCa cell lines: C4-2, LNCaP, DU145, and CWRv22.1. In contrast, autophagic flux was low in TR-sensitive PC3 cells, leading to accumulation of p62-aggregates. Pharmacologic (chloroquine or 3-methyladenine) and genetic (shATG7 or shLAMP2) inhibition of autophagy led to cell death in TR-resistant C4-2 cells. shATG7-expressing PC3 cells, were less sensitive to TR-induced cell death whereas those shLAMP2-expressing were as sensitive as shControl-expressing PC3 cells. Inhibition of autophagic flux using chloroquine prevented clearance of p62 aggregates, leading to caspase-8 activation and cell death in C4-2 cells. In PC3 cells, inhibition of autophagy induction prevented p62 accumulation and hence caspase-8 activation.

Conclusions

We show that p62 overexpression correlates with advanced stage human PCa. Pharmacologic and genetic inhibition of autophagy in PCa cell lines indicate that autophagic flux can determine the cellular response to TR by regulating caspase-8 activation. Thus, combining various autophagic inhibitors may have a differential impact on TR-induced cell death.