Oligomeric proanthocyanidins (OPCs) from grape seed extract suppress the activity of ABC transporters in overcoming chemoresistance in colorectal cancer cells.

Multidrug resistance is a major hindrance in managing cancer. By performing a series of experiments in chemoresistant colorectal cancer cell lines, we demonstrate that oligomeric proanthocyanidins (OPCs) from grape seed extracts can sensitize both acquired (HCT116-FOr cells) and innately chemoresistant (H716 cells) cancer cells to chemotherapeutic drugs, 5-fluorouracil (5FU) and oxaliplatin, by inhibiting adenosine triphosphate-binding cassette (ABC) transporter proteins. When combined with chemotherapeutic drugs, OPCs significantly inhibited growth of the chemoresistant cells (P < 0.05 to < 0.001) and decreased the expression of several key ABC transporters. Moreover, the activity of the ABC transporters was also significantly decreased by OPCs in the cell lines (P < 0.05). We further confirmed that co-treatment with OPCs sensitized the chemoresistant cells to 5FU and oxaliplatin, as observed by improvement in cell cycle arrest, double-strand breaks and p53 accumulation in these cells. In addition, we confirmed that co-administration of OPCs with chemotherapeutic drugs significantly decreased chemoresistant xenograft tumor growth in mice (P < 0.05). Together, our study illuminates the downregulation of multiple ABC transporters as a mechanism by which OPCs overcome chemoresistance in cancer cells and may serve as adjunctive treatments in patients with refractory colorectal cancer.

A Structure-Activity Relationship Study of Bis-Benzamides as Inhibitors of Androgen Receptor-Coactivator Interaction.

The interaction between androgen receptor (AR) and coactivator proteins plays a critical role in AR-mediated prostate cancer (PCa) cell growth, thus its inhibition is emerging as a promising strategy for PCa treatment. To develop potent inhibitors of the AR-coactivator interaction, we have designed and synthesized a series of bis-benzamides by modifying functional groups at the N/C-terminus and side chains. A structure-activity relationship study showed that the nitro group at the N-terminus of the bis-benzamide is essential for its biological activity while the C-terminus can have either a methyl ester or a primary carboxamide. Surveying the side chains with various alkyl groups led to the identification of a potent compound 14d that exhibited antiproliferative activity (IC50 value of 16 nM) on PCa cells. In addition, biochemical studies showed that 14d exerts its anticancer activity by inhibiting the AR-PELP1 interaction and AR transactivation.

Mechanistic insights into anticancer properties of oligomeric proanthocyanidins from grape seeds in colorectal cancer.

Although the anticancer properties of oligomeric proanthocyanidins (OPCs) from grape seeds have been well recognized, the molecular mechanisms by which they exert anticancer effects are poorly understood. In this study, through comprehensive RNA-sequencing-based gene expression profiling in multiple colorectal cancer cell lines, we for the first time illuminate the genome-wide effects of OPCs from grape seeds in colorectal cancer. Our data revealed that OPCs affect several key cancer-associated genes. In particular, genes involved in cell cycle and DNA replication were most significantly and consistently altered by OPCs across multiple cell lines. Intriguingly, our in vivo experiments showed that OPCs were significantly more potent at decreasing xenograft tumor growth compared with the unfractionated grape seed extract (GSE) that includes the larger polymers of proanthocyanidins. These findings were further confirmed in colorectal cancer patient-derived organoids, wherein OPCs more potently inhibited the formation of organoids compared with GSE. Furthermore, we validated alteration of cell cycle and DNA replication-associated genes in cancer cell lines, mice xenografts as well as patient-derived organoids. Overall, this study provides an unbiased and comprehensive look at the mechanisms by which OPCs exert anticancer properties in colorectal cancer.

Curcumin sensitizes pancreatic cancer cells to gemcitabine by attenuating PRC2 subunit EZH2, and the lncRNA PVT1 expression.

Development of resistance to chemotherapeutic drugs is a major challenge in the care of patients with pancreatic ductal adenocarcinoma (PDAC). Acquired resistance to chemotherapeutic agents in PDAC has been linked to a subset of cancer cells termed 'cancer stem cells' (CSCs). Therefore, an improved understanding of the molecular events underlying the development of pancreatic CSCs is required to identify new therapeutic targets to overcome chemoresistance. Accumulating evidence indicates that curcumin, a phenolic compound extracted from turmeric, can overcome de novo chemoresistance and re-sensitize tumors to various chemotherapeutic agents. However, the underlying mechanisms for curcumin-mediated chemosensitization remain unclear. The Enhancer of Zeste Homolog-2 (EZH2) subunit of Polycomb Repressive Complex 2 (PRC2) was recently identified as a key player regulating drug resistance. EZH2 mediates interaction with several long non-coding RNAs (lncRNAs) to modulate epithelial-mesenchymal transition and cancer stemness, phenomena commonly associated with drug resistance. Here, we report the re-sensitization of chemoresistant PDAC cells by curcumin through the inhibition of the PRC2-PVT1-c-Myc axis. Using gemcitabine-resistant PDAC cell lines, we found that curcumin sensitized chemoresistant cancer cells by inhibiting the expression of the PRC2 subunit EZH2 and its related lncRNA PVT1. Curcumin was also found to prevent the formation of spheroids, a hallmark of CSCs, and to down-regulate several self-renewal driving genes. In addition, we confirmed our in vitro findings in a xenograft mouse model where curcumin inhibited gemcitabine-resistant tumor growth. Overall, this study indicates clinical relevance for combining curcumin with chemotherapy to overcome chemoresistance in PDAC.

Ablation of the oncogenic transcription factor ERG by deubiquitinase inhibition in prostate cancer.

The transcription factor E-twenty-six related gene (ERG), which is overexpressed through gene fusion with the androgen-responsive gene transmembrane protease, serine 2 (TMPRSS2) in ∼40% of prostate tumors, is a key driver of prostate carcinogenesis. Ablation of ERG would disrupt a key oncogenic transcriptional circuit and could be a promising therapeutic strategy for prostate cancer treatment. Here, we show that ubiquitin-specific peptidase 9, X-linked (USP9X), a deubiquitinase enzyme, binds ERG in VCaP prostate cancer cells expressing TMPRSS2-ERG and deubiquitinates ERG in vitro. USP9X knockdown resulted in increased levels of ubiquitinated ERG and was coupled with depletion of ERG. Treatment with the USP9X inhibitor WP1130 resulted in ERG degradation both in vivo and in vitro, impaired the expression of genes enriched in ERG and prostate cancer relevant gene signatures in microarray analyses, and inhibited growth of ERG-positive tumors in three mouse xenograft models. Thus, we identified USP9X as a potential therapeutic target in prostate cancer cells and established WP1130 as a lead compound for the development of ERG-depleting drugs.

Mouse Spermatogenesis Requires Classical and Nonclassical Testosterone Signaling.

Testosterone acts though the androgen receptor in Sertoli cells to support germ cell development (spermatogenesis) and male fertility, but the molecular and cellular mechanisms by which testosterone acts are not well understood. Previously, we found that in addition to acting through androgen receptor to directly regulate gene expression (classical testosterone signaling pathway), testosterone acts through a nonclassical pathway via the androgen receptor to rapidly activate kinases that are known to regulate spermatogenesis. In this study, we provide the first evidence that nonclassical testosterone signaling occurs in vivo as the MAP kinase cascade is rapidly activated in Sertoli cells within the testis by increasing testosterone levels in the rat. We find that either classical or nonclassical signaling regulates testosterone-mediated Rhox5 gene expression in Sertoli cells within testis explants. The selective activation of classical or nonclassical signaling pathways in Sertoli cells within testis explants also resulted in the differential activation of the Zbtb16 and c-Kit genes in adjacent spermatogonia germ cells. Delivery of an inhibitor of either pathway to Sertoli cells of mouse testes disrupted the blood-testis barrier that is essential for spermatogenesis. Furthermore, an inhibitor of nonclassical testosterone signaling blocked meiosis in pubertal mice and caused the loss of meiotic and postmeiotic germ cells in adult mouse testes. An inhibitor of the classical pathway caused the premature release of immature germ cells. Collectively, these observations indicate that classical and nonclassical testosterone signaling regulate overlapping and distinct functions that are required for the maintenance of spermatogenesis and male fertility.

Distal Versus Proximal Radial Artery Access for Cardiac Catheterization: 30-Day Outcomes of the DIPRA Study.

Background Proximal radial artery (pRA) access for cardiac catheterization is safe but can jeopardize subsequent use of the artery because of occlusion. Distal radial artery (dRA) access in the anatomical snuffbox preserves the radial artery, but safety and potential detrimental effects on hand function are unknown. Methods and Results In the DIPRA (Distal Versus Proximal Radial Artery Access for Cardiac Catheterization and Intervention) study, a single-center trial, 300 patients were randomized 1:1 to cardiac catheterization through dRA or pRA. The primary end point of change in hand function from baseline to 30 days was a composite of the QuickDASH (Quick Disabilities of the Arm, Shoulder and Hand) questionnaire, hand-grip test, and thumb forefinger pinch test. Secondary end points included access feasibility and complications; 254 of 300 patients completed follow-up at 30 days; of these, 128 were randomized to dRA and 126 to pRA with balanced demographic and procedural characteristics. Both groups had similar rates of access site bleeding (dRA 0% versus pRA 1.4%; P=0.25). Six patients with dRA failed access compared with 2 patients with pRA. Radial artery occlusion occurred in 2 pRA versus none in dRA. There were no significant differences in change in hand function, median hand-grip (dRA 0 [-3.2, 3.3] versus pRA 0.7 [-2.3, 3.3] kg; P=0.21), pinch-grip (dRA -0.3 [-1.2, 0.5] versus pRA 0 [-0.9, 0.9] kg; P=0.09), and QuickDASH (dRA 0 [-4.6, 2.3] versus pRA 0 [-4.6, 2.3] points, P=0.96). There was no significant difference in the composite of hand function between pRA and dRA. Conclusions dRA is a safe strategy for cardiac catheterization with a low complication rate. Compared with pRA, there is no increased risk of hand dysfunction at 30 days. Registration URL: https://www.ClinicalTrials.gov. Unique identifier: NCT04318990.

Distal Versus Proximal Radial Artery Access for Cardiac Catheterization and Intervention: Design and Rationale of the DIPRA Trial.

BACKGROUND: Radial artery (RA) catheterization is the access of choice over femoral artery access for most interventional vascular procedures given its safety and faster patient recovery. There has been growing interest in distal radial artery (dRA) access as an alternative to the conventional proximal radial artery (pRA) access. Preserving the RA is important which serves as a potential conduit for future coronary artery bypass surgery, dialysis conduit or preserve the artery for future cardiovascular procedures. The dRA runs in close proximity to the radial nerve, which raises the concern of potential detrimental effects on hand function. STUDY DESIGN: The Distal versus Proximal Radial Artery Access for cardiac catheterization and intervention (DIPRA) trial is a prospective, randomized, parallel-controlled, open-label, single center study evaluating the outcomes of hand function and effectiveness of dRA compared to pRA access in patients undergoing cardiac catheterization. The eligible subjects will be randomized to dRA and pRA access in a (1:1) fashion. The primary end point is an evaluation of hand function at one and twelve months follow-up. Secondary end points include rates of access site hematoma, access site bleeding, other vascular access complications, arterial access success rate, and RA occlusion at one and twelve months follow up. CONCLUSION: Effects of dRA on hand function remains unknown and it's use questionable in the presence of a widely accepted pRA. DIPRA trial is designed to determine the safety and effectiveness of dRA for diagnostic and interventional cardiovascular procedures compared to the standard of care pRA.

Oligomeric proanthocyanidins (OPCs) target cancer stem-like cells and suppress tumor organoid formation in colorectal cancer.

Proanthocyanidins are a heterogeneous group of flavan-3-ol or flavan-3,4-diol oligomers present in various fruits and vegetables. In particular, the smaller oligomeric subset of proanthocyanidins, termed the oligomeric proanthocyanidins (OPCs) appear to have potent anti-tumorigenic properties, but the underlying mechanisms for their effectiveness remain unclear. Herein, we utilized a series of in vitro, in vivo and patient-derived organoid approaches to systematically investigate the chemoprotective role of OPCs in colorectal cancer. OPCs exerted anti-tumorigenic effects through inhibition of cellular proliferation, and induced apoptosis and cell cycle arrest. Intriguingly, OPCs suppressed spheroid derived cancer stem-like cell formation and decreased the expression of intestinal cancer stem cell markers including LGR5, CD44 and CD133. Mechanistically, RNA-sequencing results confirmed that OPCs prominently interfered with developmental and self-renewal pathways and identified several self-renewal associated oncogenes targeted by OPCs. Furthermore, OPCs inhibited Hippo pathway through downregulation of its key transcriptional regulators, YAP and TAZ. Finally, we confirmed anti-tumorigenic effects of OPCs using multiple xenograft experiments and recapitulated its protective effects using patient-derived colorectal tumor organoids. Collectively, we have comprehensively assessed anti-tumorigenic properties of OPCs and our data throws light on previously unrecognized chemopreventive mechanisms of OPCs highlighting its therapeutic potential.

A combination of curcumin and oligomeric proanthocyanidins offer superior anti-tumorigenic properties in colorectal cancer.

Combining anti-cancer agents in cancer therapies is becoming increasingly popular due to improved efficacy, reduced toxicity and decreased emergence of resistance. Here, we test the hypothesis that dietary agents such as oligomeric proanthocyanidins (OPCs) and curcumin cooperatively modulate cancer-associated cellular mechanisms to inhibit carcinogenesis. By a series of in vitro assays in colorectal cancer cell lines, we showed that the anti-tumorigenic properties of the OPCs-curcumin combination were superior to the effects of individual compounds. By RNA-sequencing based gene-expression profiling in six colorectal cancer cell lines, we identified the cooperative modulation of key cancer-associated pathways such as DNA replication and cell cycle pathways. Moreover, several pathways, including protein export, glutathione metabolism and porphyrin metabolism were more effectively modulated by the combination of OPCs and curcumin. We validated genes belonging to these pathways, such as HSPA5, SEC61B, G6PD, HMOX1 and PDE3B to be cooperatively modulated by the OPCs-curcumin combination. We further confirmed that the OPCs-curcumin combination more potently suppresses colorectal carcinogenesis and modulated expression of genes identified by RNA-sequencing in mice xenografts and in colorectal cancer patient-derived organoids. Overall, by delineating the cooperative mechanisms of action of OPCs and curcumin, we make a case for the clinical co-administration of curcumin and OPCs as a treatment therapy for patients with colorectal cancer.

A patient-derived explant (PDE) model of hormone-dependent cancer.

Breast and prostate cancer research to date has largely been predicated on the use of cell lines in vitro or in vivo. These limitations have led to the development of more clinically relevant models, such as organoids or murine xenografts that utilize patient-derived material; however, issues related to low take rate, long duration of establishment, and the associated costs constrain use of these models. This study demonstrates that ex vivo culture of freshly resected breast and prostate tumor specimens obtained from surgery, termed patient-derived explants (PDEs), provides a high-throughput and cost-effective model that retains the native tissue architecture, microenvironment, cell viability, and key oncogenic drivers. The PDE model provides a unique approach for direct evaluation of drug responses on an individual patient's tumor, which is amenable to analysis using contemporary genomic technologies. The ability to rapidly evaluate drug efficacy in patient-derived material has high potential to facilitate implementation of personalized medicine approaches.

EPI-001 is a selective peroxisome proliferator-activated receptor-gamma modulator with inhibitory effects on androgen receptor expression and activity in prostate cancer.

The androgen receptor (AR) is a driver of prostate cancer (PCa) cell growth and disease progression. Therapies for advanced PCa exploit AR dependence by blocking the production or action of androgens, but these interventions inevitably fail via multiple mechanisms including mutation or deletion of the AR ligand binding domain (LBD). Thus, the development of new inhibitors which act through non-LBD interfaces is an unmet clinical need. EPI-001 is a bisphenol A-derived compound shown to bind covalently and inhibit the AR NH2-terminal domain (NTD). Here, we demonstrate that EPI-001 has general thiol alkylating activity, resulting in multilevel inhibitory effects on AR in PCa cell lines and tissues. At least one secondary mechanism of action associated with AR inhibition was found to be selective modulation of peroxisome proliferator activated receptor-gamma (PPARγ). These multi-level effects of EPI-001 resulted in inhibition of transcriptional activation units (TAUs) 1 and 5 of the AR NTD, and reduced AR expression. EPI-001 inhibited growth of AR-positive and AR-negative PCa cell lines, with the highest sensitivity observed in LNCaP cells. Overall, this study provides new mechanistic insights to the chemical biology of EPI-001, and raises key issues regarding the use of covalent inhibitors of the intrinsically unstructured AR NTD.

The social network of PELP1 and its implications in breast and prostate cancers.

Proline, glutamic acid- and leucine-rich protein 1 (PELP1) is a multi-domain scaffold protein that serves as a platform for various protein-protein interactions between steroid receptors (SRs) and signaling factors and cell cycle, transcriptional, cytoskeletal, and epigenetic remodelers. PELP1 is known to be a coregulator of transcription and participates in the nuclear and extranuclear functions of SRs, ribosome biogenesis, and cell cycle progression. The expression and localization of PELP1 are dysregulated in hormonal cancers including breast and prostate cancers. This review focuses on the interactive functions and therapeutic and prognostic significance of PELP1 in breast and prostate cancers.

Peptidomimetic targeting of critical androgen receptor-coregulator interactions in prostate cancer.

The growth of advanced prostate cancer depends on androgen receptor signalling, however treatment options are limited. Here we report the disruption of specific protein-protein interactions involving LXXLL motifs in androgen receptor-coregulator proteins such as PELP1 using a novel, small molecule peptidomimetic (D2). D2 is stable, non-toxic and efficiently taken up by prostate cancer cells. Importantly, D2 blocks androgen-induced nuclear uptake and genomic activity of the androgen receptor. Furthermore, D2 abrogates androgen-induced proliferation of prostate cancer cells in vitro with an IC50 of 40 nM, and inhibits tumour growth in a mouse xenograft model. D2 also disrupts androgen receptor-coregulator interactions in ex vivo cultures of primary human prostate tumours. These findings provide evidence that targeting androgen receptor-coregulator interactions using peptidomimetics may be a viable therapeutic approach for patients with advanced prostate cancer.

Central role for PELP1 in nonandrogenic activation of the androgen receptor in prostate cancer.

The ability of 17ß-estradiol (E2) to regulate the proliferation of prostate cancer (PCa) cells in the absence of androgen is poorly understood. Here, we show the predominant estrogen receptor (ER) isoform expressed in PCa specimens and cell lines is ERß. Our data indicate that E2 induces the formation of a complex between androgen receptor (AR), ERß, and a proline-, glutamic acid-, and leucine-rich cofactor protein 1 (PELP1) in PCa cells. This protein complex is formed on AR's cognate DNA-responsive elements on the promoter in response to E2. Formation of this complex enables the transcription of AR-responsive genes in response to E2. Knockdown of PELP1, AR, or ERß blocks the assembly of this complex, blocks E2-induced genomic activation of AR-regulated genes, and blocks E2-stimulated proliferation of PCa cells. Overall, this study shows that PELP1 may enable E2-induced AR signaling by forming a protein complex between AR, ERß, and PELP1 on the DNA, leading to the proliferation of PCa cells in the absence of androgen. PELP1 may bridge the signal between E2 bound to ERß and AR and thus allow for cross talk between these steroid receptors. These data suggest a novel mechanism of AR activation in the absence of androgens in PCa cells. Our data indicate that disruption of the complex between AR and PELP1 may be a viable therapeutic strategy in advanced PCa.

Dual roles of PARP-1 promote cancer growth and progression.

UNLABELLED: PARP-1 is an abundant nuclear enzyme that modifies substrates by poly(ADP-ribose)-ylation. PARP-1 has well-described functions in DNA damage repair and also functions as a context-specific regulator of transcription factors. With multiple models, data show that PARP-1 elicits protumorigenic effects in androgen receptor (AR)-positive prostate cancer cells, in both the presence and absence of genotoxic insult. Mechanistically, PARP-1 is recruited to sites of AR function, therein promoting AR occupancy and AR function. It was further confirmed in genetically defined systems that PARP-1 supports AR transcriptional function, and that in models of advanced prostate cancer, PARP-1 enzymatic activity is enhanced, further linking PARP-1 to AR activity and disease progression. In vivo analyses show that PARP-1 activity is required for AR function in xenograft tumors, as well as tumor cell growth in vivo and generation and maintenance of castration resistance. Finally, in a novel explant system of primary human tumors, targeting PARP-1 potently suppresses tumor cell proliferation. Collectively, these studies identify novel functions of PARP-1 in promoting disease progression, and ultimately suggest that the dual functions of PARP-1 can be targeted in human prostate cancer to suppress tumor growth and progression to castration resistance. SIGNIFICANCE: These studies introduce a paradigm shift with regard to PARP-1 function in human malignancy, and suggest that the dual functions of PARP-1 in DNA damage repair and transcription factor regulation can be leveraged to suppress pathways critical for promalignant phenotypes in prostate cancer cells by modulation of the DNA damage response and hormone signaling pathways. The combined studies highlight the importance of dual PARP-1 function in malignancy and provide the basis for therapeutic targeting.