BackgroundSurvivin is expressed in prostate cancer (PCa), and its downregulation sensitizes PCa cells to chemotherapeutic agents in vitro and in vivo. Small membrane-bound vesicles called exosomes, secreted from the endosomal membrane compartment, contain RNA and protein that they readily transport via exosome internalization into recipient cells. Recent progress has shown that tumor-derived exosomes play multiple roles in tumor growth and metastasis and may produce these functions via immune escape, tumor invasion and angiogenesis. Furthermore, exosome analysis may provide novel biomarkers to diagnose or monitor PCa treatment.MethodsExosomes were purified from the plasma and serum from 39 PCa patients, 20 BPH patients, 8 prostate cancer recurrent and 16 healthy controls using ultracentrifugation and their quantities and qualities were quantified and visualized from both the plasma and the purified exosomes using ELISA and Western blotting, respectively.ResultsSurvivin was significantly increased in the tumor-derived samples, compared to those from BPH and controls with virtually no difference in the quantity of Survivin detected in exosomes collected from newly diagnosed patients exhibiting low (six) or high (nine) Gleason scores. Exosome Survivin levels were also higher in patients that had relapsed on chemotherapy compared to controls.ConclusionsThese studies demonstrate that Survivin exists in plasma exosomes from both normal, BPH and PCa subjects. The relative amounts of exosomal Survivin in PCa plasma was significantly higher than in those with pre-inflammatory BPH and control plasma. This differential expression of exosomal Survivin was seen with both newly diagnosed and advanced PCa subjects with high or low-grade cancers. Analysis of plasma exosomal Survivin levels may offer a convenient tool for diagnosing or monitoring PCa and may, as it is elevated in low as well as high Gleason scored samples, be used for early detection.

Standard treatment for metastatic prostate cancer (CaP) prevents ligand-activation of androgen receptor (AR). Despite initial remission, CaP progresses while relying on AR. AR transcriptional output controls CaP behavior and is an alternative therapeutic target, but its molecular regulation is poorly understood. Here, we show that action of activated AR partitions into fractions that are controlled preferentially by different coregulators. In a 452-AR-target gene panel, each of 18 clinically relevant coregulators mediates androgen-responsiveness of 0–57% genes and acts as a coactivator or corepressor in a gene-specific manner. Selectivity in coregulator-dependent AR action is reflected in differential AR binding site composition and involvement with CaP biology and progression. Isolation of a novel transcriptional mechanism in which WDR77 unites the actions of AR and p53, the major genomic drivers of lethal CaP, to control cell cycle progression provides proof-of-principle for treatment via selective interference with AR action by exploiting AR dependence on coregulators.

Exosomes are endosomal-derived nanovesicles released by normal and tumor cells which have been shown to transfer functionally active protein, lipids, mRNAs and miRNAs between cells. Varying in molecular profiles, biological roles, functional roles and protein contents, exosomes have been described as Bmulti-purpose carriers^playing a role in supporting the survival and growth of tumor cells. The IAP Survivin has been found to be present in tumor exosomes. However, the existence of other IAPs in tumor exosomes is still unknown. Survivin, cIAP1, cIAP2 and XIAP mRNA and protein are differently expressed in a panel of tumor cell lines: DLCL2, HeLa, MCF-7, Panc-1, and PC3. Exosomes were isolated from conditioned media collected from the cells from which RNA and protein were extracted. Our results provide evidence that like Survivin, XIAP, cIAP1 and cIAP2 proteins are found in tumor exosomes. The mRNA expression, however, is differentially expressed across the tumor cell lines. The presence of these bioactive molecules in exosomes may not only serve as warning signals, but also play a role in providing protection to the cancer cells against changes that are constantly occurring in the tumor microenvironment.

Objectives The inhibitor of apoptosis (IAP) proteins are critical modulators of chemotherapeutic resistance in various cancers. To address the alarming emergence of chemotherapeutic resistance in pancreatic cancer, we investigated the efficacy of the turmeric derivative curcumin in reducing IAP protein and mRNA expression resulting in pancreatic cancer cell death. Methods The pancreatic adenocarcinoma cell line PANC-1 was used to assess curcumin’s effects in pancreatic cancer. Curcumin uptake was measured by spectral analysis and fluorescence microscopy. AlamarBlue and Trypan blue exclusion assays were used to determine PANC-1 cell viability following curcumin treatment. Visualization of PANC-1 cell death was performed using Hoffman Modulation Contrast microscopy. Western blot and PCR analyses were used to evaluate curcumin’s effects on IAP protein and mRNA expression. Results Curcumin enters PANC-1 cells and is ubiquitously present within the cell following treatment. Furthermore, curcumin reduces cell viability and induces morphological changes characteristic of cell death. Additionally, curcumin decreases IAP protein and mRNA expression in PANC-1 cells. Conclusions These data demonstrate that PANC-1 cells are sensitive to curcumin treatment. Furthermore, curcumin as a potential therapeutic tool for overcoming chemotherapeutic resistance mediated by IAPs, supports a role for curcumin as part of the therapeutic approach for pancreatic cancer.

Survivin is one of the most important members of the inhibitors of apoptosis protein family, as it is expressed in most human cancers but is absent in normal, differentiated tissues. Lending to its importance, survivin has proven associations with apoptosis and cell cycle control, and has more recently been shown to modulate the tumor microenvironment and immune evasion as a result of its extracellular localization. Upregulation of survivin has been found in many cancers including breast, prostate, pancreatic, and hematological malignancies, and it may prove to be associated with the advanced presentation, poorer prognosis, and lower survival rates observed in ethnically diverse populations.

35 Background: The inhibitor of apoptosis (IAP) protein Survivin and its splice variants are differentially expressed in breast cancer tissues and have recently been shown to be released from tumor cells via small membrane-bound vesicles called exosomes. Tumor-derived exosomes play multiple roles in tumor growth and metastasis and may produce these functions by impacting immune escape, tumor invasion and angiogenesis. We, therefore, hypothesize that analysis of exosomal Survivin and its splice variants may provide a novel biomarker for early diagnosis of breast cancer in addition to current recommended methods. Methods: Twenty paired breast cancer patient’s sera and tumor tissue, and ten normal control sera were used for analysis. ELISA was performed to quantitate serum levels of Survivin. Exosomes were isolated from the sera using Exoquick. RT-PCR, western blots with densitometry, and immunohistochemistry followed by confocal microscopy were then performed. Results: For each breast cancer patient serum, Survivin levels were significantly higher compared to control (p<0.05). While Survivin and the DEx3 splice variant expression and localization were similar, differential expression of Survivin and the 2B splice variant protein and mRNA existed in the exosomes and tissue samples. Survivin and -DEx3 proteins were the predominant forms detected in 100% (20/20) of the breast cancer tissues evaluated, whereas a more variable expression of Survivin-2B, with enhanced levels found in areas of necrosis. We also for the first time here show the exosomal localization of Survivin and its splice variants DEx3 and 2B in sera from breast cancer patients. Conclusions: The result of the proposed project supports our hypothesis that differential expression of exosomal-Survivin and its alternative splice variants may serve as a diagnostic marker in breast cancer patients. For future direction, we plan to study the prognostic value of exosomal-Survivin and its splice variants on a large panel of primary breast cancers within a setting of well-followed clinical outcomes.

Quassinoids often exhibit anti-oxidant and anti-proliferative activity. Emerging evidence suggests that these natural metabolites also display chemopreventive actions. In this study, we investigated the potential for the quassinoid glaucarubulone glucoside (Gg), isolated from the endemic Jamaican plant Castela macrophylla (Simaroubaceae), to display potent cytotoxicity and inhibit human cytochrome P450s (CYPs), particularly CYP1A enzymes, known to convert polyaromatic hydrocarbons (PAHs) into carcinogenic metabolites. Gg reduced the viability of MCF-7 breast adenocarcinoma cells (IC50 = 121 nM) to a greater extent than standard of care anticancer agents 5-fluorouracil, tamoxifen (IC50 > 10 μM) and the tamoxifen metabolite 4-hydroxytamoxifen (IC50 = 2.6 μM), yet was not cytotoxic to non-tumourigenic MCF-10A breast epithelial cells. Additionally, Gg induced MCF-7 breast cancer cell death. Gg blocked increases in reactive oxygen species in MCF-10A cells mediated by PAH benzo[a]pyrene (B[a]P) metabolite benzo[a]pyrene 1,6 quinone, yet down-regulated the expression of genes that promote antioxidant activity in MCF-7 cells. This implies that Gg exhibits anti-oxidant and cytoprotective actions in non-tumourigenic breast epithelial cells and pro-oxidant, cytotoxic actions in breast cancer cells. Furthermore, Gg inhibited the activities of human CYP1A according to non-competitive kinetics and attenuated the ability of B[a]P to induce CYP1A gene expression in MCF-7 cells. These data indicate that Gg selectively suppresses MCF-7 breast cancer cell growth without impacting non-tumourigenic breast epithelial cells and blocks B[a]P-mediated CYP1A induction. Taken together, our data provide a rationale for further investigations of Gg and similar plant isolates as potential agents to treat and prevent breast cancer.

New agent development, mechanistic understanding, and combinatorial partnerships with known and novel modalities continue to be important in the study of pancreatic cancer and its improved treatment. In this study, known antimetabolite drugs such as gemcitabine (ribonucleotide reductase inhibitor) and 5-fluorouracil (thymidylate synthase inhibitor) were compared with novel members of these two drug families in the treatment of a chemoresistant pancreatic cancer cell line PANC-1. Cellular survival data, along with protein and messenger ribonucleic acid expression for survivin, XIAP, cIAP1, and cIAP2, were compared from both the cell cytoplasm and from exosomes after single modality treatment. While all antimetabolite drugs killed PANC-1 cells in a time- and dose-dependent manner, neither family significantly altered the cytosolic protein level of the four inhibitors of apoptosis (IAPs) investigated. Survivin, XIAP, cIAP1, and cIAP2 were found localized to exosomes where no significant difference in expression was recorded. This inability for significant and long-lasting expression may be a reason why pancreatic cancer lacks responsiveness to these and other cancer-killing agents. Continued investigation is required to determine the responsibilities of these IAPs in their role in chemoresistance in pancreatic adenocarcinoma.