Pancreatic adenocarcinoma Ryan, David P; Hong, Theodore S; Bardeesy, Nabeel
The New England journal of medicine,
09/2014, Volume:
371, Issue:
11
Journal Article
Intrahepatic cholangiocarcinoma (iCCA) is a molecularly heterogeneous hepatobiliary neoplasm with poor prognosis and limited therapeutic options. The incidence of this neoplasm is growing globally. ...One third of iCCA tumors are amenable to surgical resection, but most cases are diagnosed at advanced stages with chemotherapy as the only established standard of practice. No molecular therapies are currently available for the treatment of this neoplasm. The poor understanding of the biology of iCCA and the lack of known oncogenic addiction loops has hindered the development of effective targeted therapies. Studies with sophisticated animal models defined IDH mutation as the first gatekeeper in the carcinogenic process and led to the discovery of striking alternative cellular origins. RNA- and exome-sequencing technologies revealed the presence of recurrent novel fusion events (FGFR2 and ROS1 fusions) and somatic mutations in metabolic (IDH1/2) and chromatin-remodeling genes (ARID1A, BAP1). These latest advancements along with known mutations in KRAS/BRAF/EGFR and 11q13 high-level amplification have contributed to a better understanding of the landscape of molecular alterations in iCCA. More than 100 clinical trials testing molecular therapies alone or in combination with chemotherapy including iCCA patients have not reported conclusive clinical benefits. Recent discoveries have shown that up to 70% of iCCA patients harbor potential actionable alterations that are amenable to therapeutic targeting in early clinical trials. Thus, the first biomarker-driven trials are currently underway.
Background and Aims
Activation of the antitumor immune response using programmed death receptor‐1 (PD‐1) blockade showed benefit only in a fraction of patients with hepatocellular carcinoma (HCC). ...Combining PD‐1 blockade with antiangiogenesis has shown promise in substantially increasing the fraction of patients with HCC who respond to treatment, but the mechanism of this interaction is unknown.
Approach and Results
We recapitulated these clinical outcomes using orthotopic—grafted or induced—murine models of HCC. Specific blockade of vascular endothelial receptor 2 (VEGFR‐2) using a murine antibody significantly delayed primary tumor growth but failed to prolong survival, while anti‐PD‐1 antibody treatment alone conferred a minor survival advantage in one model. However, dual anti‐PD‐1/VEGFR‐2 therapy significantly inhibited primary tumor growth and doubled survival in both models. Combination therapy reprogrammed the immune microenvironment by increasing cluster of differentiation 8–positive (CD8+) cytotoxic T cell infiltration and activation, shifting the M1/M2 ratio of tumor‐associated macrophages and reducing T regulatory cell (Treg) and chemokine (C‐C motif) receptor 2–positive monocyte infiltration in HCC tissue. In these models, VEGFR‐2 was selectively expressed in tumor endothelial cells. Using spheroid cultures of HCC tissue, we found that PD‐ligand 1 expression in HCC cells was induced in a paracrine manner upon anti‐VEGFR‐2 blockade in endothelial cells in part through interferon‐gamma expression. Moreover, we found that VEGFR‐2 blockade increased PD‐1 expression in tumor‐infiltrating CD4+ cells. We also found that under anti‐PD‐1 therapy, CD4+ cells promote normalized vessel formation in the face of antiangiogenic therapy with anti‐VEGFR‐2 antibody.
Conclusions
We show that dual anti‐PD‐1/VEGFR‐2 therapy has a durable vessel fortification effect in HCC and can overcome treatment resistance to either treatment alone and increase overall survival in both anti‐PD‐1 therapy–resistant and anti‐PD‐1 therapy–responsive HCC models.
The mechanisms of hepatitis C virus (HCV) infection, liver disease progression, and hepatocarcinogenesis are only partially understood. We performed genomic, proteomic, and metabolomic analyses of ...HCV-infected cells and chimeric mice to learn more about these processes.
Huh7.5.1dif (hepatocyte-like cells) were infected with culture-derived HCV and used in RNA sequencing, proteomic, metabolomic, and integrative genomic analyses. uPA/SCID (urokinase-type plasminogen activator/severe combined immunodeficiency) mice were injected with serum from HCV-infected patients; 8 weeks later, liver tissues were collected and analyzed by RNA sequencing and proteomics. Using differential expression, gene set enrichment analyses, and protein interaction mapping, we identified pathways that changed in response to HCV infection. We validated our findings in studies of liver tissues from 216 patients with HCV infection and early-stage cirrhosis and paired biopsy specimens from 99 patients with hepatocellular carcinoma, including 17 patients with histologic features of steatohepatitis. Cirrhotic liver tissues from patients with HCV infection were classified into 2 groups based on relative peroxisome function; outcomes assessed included Child–Pugh class, development of hepatocellular carcinoma, survival, and steatohepatitis. Hepatocellular carcinomas were classified according to steatohepatitis; the outcome was relative peroxisomal function.
We quantified 21,950 messenger RNAs (mRNAs) and 8297 proteins in HCV-infected cells. Upon HCV infection of hepatocyte-like cells and chimeric mice, we observed significant changes in levels of mRNAs and proteins involved in metabolism and hepatocarcinogenesis. HCV infection of hepatocyte-like cells significantly increased levels of the mRNAs, but not proteins, that regulate the innate immune response; we believe this was due to the inhibition of translation in these cells. HCV infection of hepatocyte-like cells increased glucose consumption and metabolism and the STAT3 signaling pathway and reduced peroxisome function. Peroxisomes mediate β-oxidation of very long-chain fatty acids; we found intracellular accumulation of very long-chain fatty acids in HCV-infected cells, which is also observed in patients with fatty liver disease. Cells in livers from HCV-infected mice had significant reductions in levels of the mRNAs and proteins associated with peroxisome function, indicating perturbation of peroxisomes. We found that defects in peroxisome function were associated with outcomes and features of HCV-associated cirrhosis, fatty liver disease, and hepatocellular carcinoma in patients.
We performed combined transcriptome, proteome, and metabolome analyses of liver tissues from HCV-infected hepatocyte-like cells and HCV-infected mice. We found that HCV infection increases glucose metabolism and the STAT3 signaling pathway and thereby reduces peroxisome function; alterations in the expression levels of peroxisome genes were associated with outcomes of patients with liver diseases. These findings provide insights into liver disease pathogenesis and might be used to identify new therapeutic targets.
Activation of cellular stress response pathways to maintain metabolic homeostasis is emerging as a critical growth and survival mechanism in many cancers. The pathogenesis of pancreatic ductal ...adenocarcinoma (PDA) requires high levels of autophagy, a conserved self-degradative process. However, the regulatory circuits that activate autophagy and reprogram PDA cell metabolism are unknown. Here we show that autophagy induction in PDA occurs as part of a broader transcriptional program that coordinates activation of lysosome biogenesis and function, and nutrient scavenging, mediated by the MiT/TFE family of transcription factors. In human PDA cells, the MiT/TFE proteins--MITF, TFE3 and TFEB--are decoupled from regulatory mechanisms that control their cytoplasmic retention. Increased nuclear import in turn drives the expression of a coherent network of genes that induce high levels of lysosomal catabolic function essential for PDA growth. Unbiased global metabolite profiling reveals that MiT/TFE-dependent autophagy-lysosome activation is specifically required to maintain intracellular amino acid pools. These results identify the MiT/TFE proteins as master regulators of metabolic reprogramming in pancreatic cancer and demonstrate that transcriptional activation of clearance pathways converging on the lysosome is a novel hallmark of aggressive malignancy.
The transcriptional co-activator YAP is an evolutionarily conserved regulator of organ size and progenitor cell proliferation. YAP is overexpressed at high frequency in many common human cancers and ...can directly drive cancer development in mouse models. YAP abundance and nuclear localization are negatively regulated by the Hippo kinase cascade, which, in epithelia, is activated by physiological cell-cell contact. Recent work in intestinal epithelium has established that YAP is constitutively inhibited by the Hippo pathway and entirely dispensable for normal development and homeostasis. YAP serves only in a standby capacity; should cell-cell contact be abrogated, as after intestinal damage, the loss of Hippo input permits increased YAP abundance and nuclear residence. In turn, YAP cooperates with β-catenin to transactivate genes that promote stem cell expansion for epithelial repair. This interplay between overexpressed YAP and β-catenin also drives proliferation of colon cancer cells. The dispensability of YAP in normal intestine makes YAP's expression or outputs attractive targets for cancer therapy.
Summary Hepatitis C virus (HCV) is one of the major aetiologic agents that causes hepatocellular carcinoma (HCC) by generating an inflammatory, fibrogenic, and carcinogenic tissue microenvironment in ...the liver. HCV-induced HCC is a rational target for cancer preventive intervention because of the clear-cut high-risk condition, cirrhosis, associated with high cancer incidence (1% to 7% per year). Studies have elucidated direct and indirect carcinogenic effects of HCV, which have in turn led to the identification of candidate HCC chemoprevention targets. Selective molecular targeted agents may enable personalized strategies for HCC chemoprevention. In addition, multiple experimental and epidemiological studies suggest the potential value of generic drugs or dietary supplements targeting inflammation, oxidant stress, or metabolic derangements as possible HCC chemopreventive agents. While the successful use of highly effective direct-acting antiviral agents will make important inroads into reducing long-term HCC risk, there will remain an important role for HCC chemoprevention even after viral cure, given the persistence of HCC risk in persons with advanced HCV fibrosis, as shown in recent studies. The successful development of cancer preventive therapies will be more challenging compared to cancer therapeutics because of the requirement for larger and longer clinical trials and the need for a safer toxicity profile given its use as a preventive agent. Molecular biomarkers to selectively identify high-risk population could help mitigate these challenges. Genome-wide, unbiased molecular characterization, high-throughput drug/gene screening, experimental model-based functional analysis, and systems-level in silico modelling are expected to complement each other to facilitate discovery of new HCC chemoprevention targets and therapies.
Organ development is a complex process governed by the interplay of several signalling pathways that have critical functions in the regulation of cell growth and proliferation. Over the past years, ...the Hippo pathway has emerged as a key regulator of organ size. Perturbation of this pathway has been shown to play important roles in tumorigenesis. YAP, the main downstream target of the mammalian Hippo pathway, promotes organ growth, yet the underlying molecular mechanism of this regulation remains unclear. Here we provide evidence that YAP activates the mammalian target of rapamycin (mTOR), a major regulator of cell growth. We have identified the tumour suppressor PTEN, an upstream negative regulator of mTOR, as a critical mediator of YAP in mTOR regulation. We demonstrate that YAP downregulates PTEN by inducing miR-29 to inhibit PTEN translation. Last, we show that PI(3)K–mTOR is a pathway modulated by YAP to regulate cell size, tissue growth and hyperplasia. Our studies reveal a functional link between Hippo and PI(3)K–mTOR, providing a molecular basis for the coordination of these two pathways in organ size regulation.
Sorafenib, a broad tyrosine kinase inhibitor, is the only approved systemic therapy for advanced hepatocellular carcinoma (HCC) but provides limited survival benefits. Recently, immunotherapy has ...emerged as a promising treatment strategy, but its role remains unclear in HCCs, which are associated with decreased cytotoxic CD8+ T‐lymphocyte infiltration in both murine and human tumors. Moreover, in mouse models after sorafenib treatment intratumoral hypoxia is increased and may fuel evasive resistance. Using orthotopic HCC models, we now show that increased hypoxia after sorafenib treatment promotes immunosuppression, characterized by increased intratumoral expression of the immune checkpoint inhibitor programmed death ligand‐1 and accumulation of T‐regulatory cells and M2‐type macrophages. We also show that the recruitment of immunosuppressive cells is mediated in part by hypoxia‐induced up‐regulation of stromal cell–derived 1 alpha. Inhibition of the stromal cell–derived 1 alpha receptor (C‐X‐C receptor type 4 or CXCR4) using AMD3100 prevented the polarization toward an immunosuppressive microenvironment after sorafenib treatment, inhibited tumor growth, reduced lung metastasis, and improved survival. However, the combination of AMD3100 and sorafenib did not significantly change cytotoxic CD8+ T‐lymphocyte infiltration into HCC tumors and did not modify their activation status. In separate experiments, antibody blockade of the programmed death ligand‐1 receptor programmed death receptor‐1 (PD‐1) showed antitumor effects in treatment‐naive tumors in orthotopic (grafted and genetically engineered) models of HCC. However, anti‐PD‐1 antibody treatment had additional antitumor activity only when combined with sorafenib and AMD3100 and not when combined with sorafenib alone. Conclusion: Anti‐PD‐1 treatment can boost antitumor immune responses in HCC models; when used in combination with sorafenib, anti‐PD‐1 immunotherapy shows efficacy only with concomitant targeting of the hypoxic and immunosuppressive microenvironment with agents such as CXCR4 inhibitors. (Hepatology 2015;61:1591–1602)
Pancreatic ductal adenocarcinoma (PDA) is a heterogeneous disease comprised of a basal-like subtype with mesenchymal gene signatures, undifferentiated histopathology and worse prognosis compared to ...the classical subtype. Despite their prognostic and therapeutic value, the key drivers that establish and control subtype identity remain unknown. Here, we demonstrate that PDA subtypes are not permanently encoded, and identify the GLI2 transcription factor as a master regulator of subtype inter-conversion. GLI2 is elevated in basal-like PDA lines and patient specimens, and forced GLI2 activation is sufficient to convert classical PDA cells to basal-like. Mechanistically, GLI2 upregulates expression of the pro-tumorigenic secreted protein, Osteopontin (OPN), which is especially critical for metastatic growth in vivo and adaptation to oncogenic KRAS ablation. Accordingly, elevated GLI2 and OPN levels predict shortened overall survival of PDA patients. Thus, the GLI2-OPN circuit is a driver of PDA cell plasticity that establishes and maintains an aggressive variant of this disease.
PDF
