Roberts, Lewis R

ABSTRACTBackground and ObjectiveThe aims of the present study were to investigate the thermal‐dose dependent effect of heat stress on hepatocyte and HCC cell death mechanisms using clinically relevant experimental heat stress conditions in vitro and to investigate apoptotic cell death induced by laser thermal ablation in vivo.Study Design/Materials and MethodsInstitutional Animal Care and Use Committee approved all studies. Hepatocyte and HCC cell lines were heat stressed from 37 to 60°C for 2 or 10 minutes and assessed for viability, cytotoxicity and caspase‐3/7 activity at 6 and/or 24 hours post‐treatment (N = 3). Viability experiments were repeated with the RIPK1 inhibitor Necrostatin‐1 to block necroptosis (N = 3). Rats with orthotopic HCC tumors stably expressing luciferase (N1S1luc2) were randomized to US‐guided laser ablation (3W‐45s for an intentional partial ablation; N = 6) or sham (N = 6) and followed by post‐ablation caspase‐3/7 bioluminescence imaging at 6 and 24 hours and cleaved caspase‐3 immunostaining. P < 0.05 was considered statistically significant.ResultsHeat‐stress induced apoptosis and necrosis in hepatocytes and HCC cells in a thermal dose and cell‐type dependent manner. Inhibition of RIPIK1‐mediated necroptosis induced a significant, differential increase in HCC cell viability under physiologic and hyperthermic heat stress (P < 0.001). Intentional partial laser thermal ablation induced a significant increase in caspase‐3/7 activity in the laser versus sham ablation groups at both 6 hours (10.1‐fold, P < 0.01) and 24 hours (16.7‐fold, P < 0.02). Immunohistochemistry confirmed increased cleaved caspase‐3 staining at the tumor ablation margin 24 hours post‐ablation.ConclusionsBoth regulated and non‐regulated cell death mechanisms mediate heat stress‐induced HCC cell killing and vary between hepatocytes and HCC subtypes. Apoptosis is a significant mechanism of cell death at the HCC tumor ablation margin. Lasers Surg. Med. 46:290–301, 2014. © 2014 Wiley Periodicals, Inc.

BACKGROUNDPatients diagnosed with primary sclerosing cholangitis (PSC) and dominant strictures often undergo endoscopic retrograde cholangiopancreatography with brush cytology to exclude or confirm the development of malignancy. Equivocal (atypical or suspicious) routine cytologic results may confound patient management decisions, especially in the absence of a mass on imaging. The objective of the current study was to identify independent predictors of malignancy in patients with PSC with an equivocal cytology diagnosis.METHODSPatients with PSC underwent brush cytology for routine cytology and fluorescence in situ hybridization (FISH) during endoscopy as per standard care. FISH slides were classified as polysomy if at least 5 cells displayed a gain of ≥ 2 probes. A retrospective search identified 102 patients without a mass lesion noted on initial imaging studies, an equivocal routine cytology, and ≥ 2 years of follow‐up.RESULTSOf 102 patients, 30 (29%) with an equivocal cytology result developed cancer within 2 years. Serum carbohydrate antigen 19‐9 (CA 19‐9) levels ≥ 129 U/mL (hazard ratio [HR] 3.19; P = .001) and polysomy (HR 8.70; P < .001) were each found to be predictive of cancer. Of 10 patients who had elevated CA 19‐9 levels and polysomy, all went on to develop cancer (9 within 2 years). Although only 10 patients were included in this subset, the combination of elevated CA 19‐9 and polysomy was found to be predictive of cancer (HR 10.92; P < .001).CONCLUSIONSPolysomy by FISH identified those patients most likely to have or develop malignancy in the challenging clinical scenario of PSC with no mass at baseline and equivocal cytology. The combination of an elevated serum CA 19‐9 level with polysomy is highly suspicious for the presence of malignancy. Cancer (Cancer Cytopathol) 2013;121:708–717. © 2013 American Cancer Society.

Abstract Cancer-associated fibroblasts (CAF) are abundant in the stroma of desmoplastic cancers where they promote tumor progression. CAFs are “activated” and as such may be uniquely susceptible to apoptosis. Using cholangiocarcinoma as a desmoplastic tumor model, we investigated the sensitivity of liver CAFs to the cytotoxic drug navitoclax, a BH3 mimetic. Navitoclax induced apoptosis in CAF and in myofibroblastic human hepatic stellate cells but lacked similar effects in quiescent fibroblasts or cholangiocarcinoma cells. Unlike cholangiocarcinoma cells, neither CAF nor quiescent fibroblasts expressed Mcl-1, a known resistance factor for navitoclax cytotoxicity. Explaining this paradox, we found that mitochondria isolated from CAFs or cells treated with navitoclax both released the apoptogenic factors Smac and cytochrome c, suggesting that they are primed for cell death. Such death priming in CAFs appeared to be due, in part, to upregulation of the proapoptotic protein Bax. Short hairpin RNA-mediated attenuation of Bax repressed navitoclax-mediated mitochondrial dysfunction, release of apoptogenic factors, and apoptotic cell death. In a syngeneic rat model of cholangiocarcinoma, navitoclax treatment triggered CAF apoptosis, diminishing expression of the desmoplastic extracellular matrix protein tenascin C, suppressing tumor outgrowth, and improving host survival. Together, our findings argue that navitoclax may be useful for destroying CAFs in the tumor microenvironment as a general strategy to attack solid tumors. Cancer Res; 73(2); 897–907. ©2012 AACR.

Abstract Background and Aims: Cholangiocarcinomas (CCA) are highly desmoplastic tumors containing abundant cancer associated myofibroblasts (CAF). An inverse association between the abundance of CAF and survival has been demonstrated in CCA, suggesting that CAF play a pivotal role in CCA development and progression. The CAF phenotype represents an ‘activated cell state’ and as such may be uniquely susceptible to apoptosis. BH3 mimetics induce apoptosis in cells ‘primed’ for cell death, representing a therapeutic strategy for cancer. Herein we examine whether CAF display a selective sensitivity to the BH3 mimetic ABT-263 and whether ABT-263 induced ablation of CAF reduces tumor growth and progression. Methods: We employed human and rat CAF, myofibroblastic human LX2 cells, human and rat control fibroblasts, the rat cholangiocarcinoma cell line BDEneu and human CCA cell lines for these studies. In-vivo experiments were conducted using a syngeneic, orthotopic rat CCA model. Results: We observed a significant and dose dependent induction of apoptosis by ABT-263 in human and rat primary CAF as well as activated LX2 cells as compared to rat BDEneu and human CCA cell lines. Comparison of Bcl-2 protein expression in quiescent fibroblasts versus CAF demonstrated a consistent upregulation of Bax in the CAF, likely explaining their enhanced sensitivity to pro-death stimuli. Indeed, ABT-263 treatment of CAF was associated with Bax activation as compared to human CCA cell lines. Finally, administration of ABT-263 decreased tumor size and metastasis in a human-like in-vivo rat model of CCA. Analysis of the rat tumors revealed a decrease in Tenascin C positive tumor stroma and an increase of TUNEL-positive apoptotic stromal cells. Conclusions: CCA associated CAF appear to be ‘primed’ for cell death, possibly due to overexpression of the pro-apoptotic Bcl-2 protein Bax. Consequently CAF display increased sensitivity to the BH3 mimetic ABT-263, which selectively depletes them from a rat in-vivo model of CCA, thereby reducing tumor growth and metastasis. Thus targeting CCA tumor stroma by inducing apoptosis in CAF may represent a new therapeutic approach in human CCA. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4905. doi:1538-7445.AM2012-4905

Abstract Cholangiocarcinomas are rare but aggressive cancers, with an increasing incidence and a dismal 5-year survival rate of less than 5%. Mutations in the genes encoding isocitrate dehydrogenase, IDH1 and IDH2, have been reported in ∼70% of gliomas, ∼20% of myeloid leukemias, ∼56% of chondrosarcomas, and ∼10% of melanomas. We discovered IDH1 and IDH2 mutations in 29 of 305 (9%) intrahepatic cholangiocarcinomas. Tumors with mutations in IDH1 or IDH2 had lower 5-hydroxymethylcytosine and higher 5-methylcytosine levels, as well as increased dimethylation of histone H3K79. Mutations in IDH1 or IDH2 were independently associated with longer time to recurrence of cholangiocarcinoma in multivariate analysis (p = 0.046). We identified 2,267 genes that were significantly hypermethylated in tumors with mutations in IDH1 or IDH2. Hypermethylated CpG sites were significantly enriched in CpG shores and in the 1500 bp upstream of annotated transcription start sites, suggesting a global regulation of transcriptional potential. Gene expression profiling of 7 IDH1/2-mutant and 20 IDH1/2-wildtype tumors revealed increased expression of citric acid cycle and oxidative phosphorylation enzymes, as well as decreased expression of cytoskeleton organization genes. Integrated analyses of DNA methylation and gene expression identified interleukin-6 and several of its downstream targets as candidates for silencing by DNA methylation. Conclusions: Cholangiocarcinomas with mutations in IDH1 or IDH2 represent a molecular subclass with distinct signaling pathway alterations. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1058. doi:1538-7445.AM2012-1058

Abstract The mammalian target of rapamycin (mTOR) consists of two distinct complexes, mTORC1 and mTORC2. mTOR plays a pivotal role in Hepatocellular Carcinoma (HCC). Previous studies indicated that inhibition of mTORC1 only moderately enhanced histone deacetylase inhibitors (HDACis)-mediated anti-tumor activity. This limited effect may be attributable to the increase of AKT activation through S6K1-IRS1-PI3K negative feedback loop triggered by selective mTORC1 inhibition. While as AKT is the downstream effector of mTORC2, we hypothesize that dual targeting of mTORC1/C2 would be more efficient in suppressing AKT and in enhancing anti-tumor activity of HDACi. In this study, the interactions between mTOR kinase inhibitors (mTORKis) and HDACis were examined in vitro using established HCC cell lines and in vivo using patient-derived HCC tumor xenografts on SCID mice. Our results demonstrate that inhibition of both mTORC1/2 not only effectively blocked mTORC1 signaling, but also abrogated negative-feedback activation of AKT caused by mTORC1 inhibition. Furthermore, inactivation of mTORC1/C2 by mTORKis substantially enhanced HDACi-induced anti-tumor activity. Either dysfunction of mTORC2 by knockdown of Rictor (a component of mTORC2), or diminution of AKT1 significantly lowered the threshold of HDACi-induced apoptosis. Lastly, in vivo study indicated that the combination of AZD8055 and Vorinostat yielded much greater tumor-growth inhibition compared to either agent alone in primary HCC xenografts without obvious adverse effects. Conclusion: Dual mTORC1/2 inhibition is more efficient than selective mTORC1 inhibition in enhancing anti-tumor activity of HDACi due to abrogation of negative-feedback activation of AKT induced by selective mTORC1 inhibition. Our findings suggest that combining regimen of mTORKi and HDACi may be an effective therapeutic strategy for HCC. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5363. doi:10.1158/1538-7445.AM2011-5363

Abstract Previous work by us and others reported decreased expression of miR-199a-3p in hepatocellular carcinoma (HCC) tissues compared to adjacent benign tissue. We report here a significant reduction of miR-199a-3p expression in 7 HCC cell lines (Huh7, HepG2, SNU182, PLC/PRF/5, Hep3B, SNU423 and SNU449) compared to primary hepatocytes. To determine if miR-199a-3p has a tumor suppressive role, miR-199a-3p mimetic was transfected into the 7 HCC cell lines. miR-199a-3p mimetic reduced cell proliferation by approximately 60% compared to control oligonucleotide in only two cell lines (SNU449 and SNU423); the proliferation of the other 5 treated cell lines was similar to control oligonucleotide. A miR-199a-3p mimetic formulated with chemical modifications to enhance stability while preserving processing reduced cell proliferation in SNU449 and SNU423 to the same extent as the commercially available miR-199a-3p mimetic. Furthermore, only the duplex miR-199a-3p mimetic, and not the guide strand alone, was effective at reducing cell viability. Since a CD44 variant was essential for c-Met signaling (Orian-Rousseau, et al., Genes Dev. 2002) and c-Met is a known miR-199a-3p target, we hypothesized that miR-199a-3p may also target CD44. Indeed, miRNA target algorithms predict miR-199a-3p to be a putative target of CD44. Immunoblotting confirmed that only the HCC lines that were sensitive to the effects of miR-199a-3p mimetic (SNU449 and SNU423) were CD44+. Direct targeting of CD44 by miR-199a-3p was confirmed using luciferase reporter assays and immunoblotting. Transfection of miR-199a-3p into SNU449 cells reduced in vitro invasion and sensitized the cells to doxorubicin; both effects were enhanced when hyaluronic acid was added to the cell cultures. An inverse correlation between the expression of miR-199a-3p and CD44 protein was noted in primary HCC tissue specimens. The anti-proliferative and anti-invasive properties of miR-199a-3p mimetic on CD44+ HCC may be a useful targeted therapy for CD44+ HCC. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1183. doi:10.1158/1538-7445.AM2011-1183

Abstract The tumor microenvironment, including stromal myofibroblasts and associated matrix proteins, regulates cancer cell invasion and proliferation. Here, we report that neuropilin-1 (NRP-1) orchestrates communications between myofibroblasts and soluble fibronectin that promote α5β1 integrin–dependent fibronectin fibril assembly, matrix stiffness, and tumor growth. Tumor growth and fibronectin fibril assembly were reduced by genetic depletion or antibody neutralization of NRP-1 from stromal myofibroblasts in vivo. Mechanistically, the increase in fibronectin fibril assembly required glycosylation of serine 612 of the extracellular domain of NRP-1, an intact intracellular NRP-1 SEA domain, and intracellular associations between NRP-1, the scaffold protein GIPC, and the nonreceptor tyrosine kinase c-Abl that augmented α5β1 fibronectin fibril assembly activity. Analysis of human cancer specimens established an association between tumoral NRP-1 levels and clinical outcome. Our findings indicate that NRP-1 activates the tumor microenvironment, thereby promoting tumor growth. These results not only identify new molecular mechanisms of fibronectin fibril assembly but also have important implications for therapeutic targeting of the myofibroblast in the tumor microenvironment. Cancer Res; 72(16); 4047–59. ©2012 AACR.