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Edward R Kastenhuber,1,2 John Craig,3 Jon Ramsey,4 Kevin M Sullivan,5 Julien Sage,6,7 Sofia de Oliveira,8 Kimberly J Riehle,5 John D Scott,5 John D Gordan,9 Nabeel Bardeesy,10,11 Ghassan K Abou-Alfa1,12 1Cancer Biology and Genetics Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA; 2Louis V. Gerstner Jr. Graduate School of Biomedical Sciences, Memorial Sloan Kettering Cancer Center, New York, NY, USA; 3Fibrolamellar Cancer Foundation, Greenwich, CT, USA; 4Department of Biochemistry, University of Vermont Cancer Center, Burlington, VT, USA; 5Northwest Liver Research Program, University of Washington, Seattle, WA, USA; 6Department of Pediatrics, Stanford University, Stanford, CA, USA; 7Department of Genetics, Stanford University, Stanford, CA, USA; 8Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, WI, USA; 9Department of Medicine, University of California, San Francisco, San Francisco, CA, USA; 10Center for Cancer Research, Massachusetts General Hospital, Boston, MA, USA; 11Department of Medicine, Harvard Medical School, Boston, MA, USA; 12Department of Medicine, Weill Cornell School of Medicine, New York, NY, USA Abstract: Fibrolamellar carcinoma is a rare liver cancer, which primarily afflicts adolescents and young adults worldwide and is frequently lethal. Given the rarity of this disease, patient recruitment for clinical trials remains a challenge. In November 2017, the Second Fibrolamellar Cancer Foundation Scientific Summit (Stamford, CT, USA) provided an opportunity for investigators to discuss recent advances in the characterization of the disease and its surrounding liver and immune context. The Fibrolamellar Cancer Foundation has thus set out a road map to identify and test therapeutic targets in the most efficient possible manner. Keywords: fibrolamellar carcinoma, liver cancer, adolescent, young adult, fusion oncogene, cyclic AMP-dependent protein kinase catalytic subunit, heat shock protein 40

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The presence of growth-induced solid stresses in tumors has been suspected for some time, but these stresses were largely estimated using mathematical models. Solid stresses can deform the surrounding tissues and compress intratumoral lymphatic and blood vessels. Compression of lymphatic vessels elevates interstitial fluid pressure, whereas compression of blood vessels reduces blood flow. Reduced blood flow, in turn, leads to hypoxia, which promotes tumor progression, immunosuppression, inflammation, invasion, and metastasis and lowers the efficacy of chemo-, radio-, and immunotherapies. Thus, strategies designed to alleviate solid stress have the potential to improve cancer treatment. However, a lack of methods for measuring solid stress has hindered the development of solid stress-alleviating drugs. Here, we present a simple technique to estimate the growth-induced solid stress accumulated within animal and human tumors, and we show that this stress can be reduced by depleting cancer cells, fibroblasts, collagen, and/or hyaluronan, resulting in improved tumor perfusion. Furthermore, we show that therapeutic depletion of carcinoma-associated fibroblasts with an inhibitor of the sonic hedgehog pathway reduces solid stress, decompresses blood and lymphatic vessels, and increases perfusion. In addition to providing insights into the mechanopathology of tumors, our approach can serve as a rapid screen for stress-reducing and perfusion-enhancing drugs. 109 15101 15108 15101-15108

ARF encodes a potent tumor suppressor that antagonizes MDM2, a negative regulator of p53. ARF also suppresses the proliferation of cells lacking p53, and loss of ARF in p53-null mice, compared with ARF or p53 singly null mice, results in a broadened tumor spectrum and decreased tumor latency. To investigate the mechanism of p53-independent tumor suppression by ARF, potential interacting proteins were identified by yeast two-hybrid screen. The antiapoptotic transcriptional corepressor C-terminal binding protein 2 (CtBP2) was identified, and ARF interactions with both CtBP1 and CtBP2 were confirmed in vitro and in vivo. Interaction with ARF resulted in proteasome-dependent CtBP degradation. Both ARF-induced CtBP degradation and CtBP small interfering RNA led to p53-independent apoptosis in colon cancer cells. ARF induction of apoptosis was dependent on its ability to interact with CtBP, and reversal of ARF-induced CtBP depletion by CtBP overexpression abrogated ARF-induced apoptosis. CtBP proteins represent putative targets for p53-independent tumor suppression by ARF.

Impaired perfusion is a hallmark of solid tumors that promotes progression, immunosuppression and treatment-resistance, and is partly caused by vascular compression from excessive extravascular stresses (Chauhan et al., 2013; Stylianopoulos et al., 2012). The extravascular stress exerted by fluid is referred to as interstitial fluid pressure (IFP) and that by solid components as solid stress (SS). IFP is near-zero in most tissues, but rises in tumors as impaired lymphatics fail to drain fluid leaking from blood vessels and IFP equilibrates with microvascular pressure (MVP) (Boucher and Jain, 1992). Due to equilibration, IFP in tumors can only transiently exceed MVP and thus cannot compress tumor vessels (Figure S1A). SS is generated as cells push and pull on their surroundings during proliferation and migration, and is transmitted by extracellular matrix (Stylianopoulos et al., 2012). SS is greatly and chronically elevated in tumors due to high cell and matrix densities, and can compress blood vessels (Figure S1A). Since the causes and consequences of elevated IFP and SS are different, strategies for alleviating these mechanical stresses are likely to be distinct. In their article, Provenzano et al. elegantly showed that hyaluronan (HA) can mechanically compress blood vessels in pancreatic ductal adenocarcinoma (PDA) (Provenzano et al., 2012). However, their proposed mechanism—that HA leads to very high IFP that collapses vessels—is not consistent with the physiology of fluid homeostasis and calls for careful assessment of IFP in PDAs. They suggest that mean IFP can reach 99 mmHg (range 75–130 mmHg), presumably higher than MVP, in the Pdx1-Cre/KrasLSL-G12D/+/p53LSL-R172H/+ (KPC) PDA model based on measurements using a piezoelectric-probe. To evaluate this, we measured IFP in KPC tumors (Figure S1B) with the wick-in-needle technique—which has been validated against the gold-standard micropipette technique (Boucher and Jain, 1992). We further measured IFP in additional PDA models, Ptf1-Cre/KrasLSL-G12D/+/p53L/+ (KPdC) and Ptf1-Cre/ROSA26-LSL-rtTA-IRES-GFP/KrasTetO-LSL-G12D/+/p53L/+ (iKPdC), which highly express HA (Figure S1E). The mean IFP was 8.1 mmHg (range 4.7–10.9 mmHg) in KPC, 3.4 mmHg (range 1.6–5.6 mmHg) in KPdC, and 6.7 mmHg (range 6.1–8.0 mmHg) in iKPdC—over an order of magnitude lower than the IFP levels reported by Provenzano et al. We also measured IFP with wick-in-needle in the tumors of four treatment-naive PDA patients (Figure S1B), and the mean IFP was 11.8 mmHg (range 6.1–16.6 mmHg). As these IFPs are in the range of typical MVPs, our established concept holds: SS compresses PDA vessels while IFP cannot. Provenzano et al. also propose that PDA IFP is not driven by equilibration with MVP because PDA vessels are non-leaky, i.e. non-permeable to macromolecules. As evidence, they state that PDA IFP measured with the piezeoelectric-probe remains elevated upon cardiac cessation, indicating that blood pressure is not driving IFP. With wick-in-needle, we found that cardiac cessation reduced IFP to zero in all three PDA models, confirming that blood pressure drives elevated IFP (Boucher and Jain, 1992). Furthermore, their hypothesis that PDA vessels are non-permeable to macromolecules is contradicted by their own data—PEGPH20, a macromolecule, clearly permeates across PDA vessels since it acts on interstitial HA. Moreover, the efficacy in PDA patients of nanoparticle-albumin-bound-paclitaxel, an FDA-approved macromolecule, also indicates that PDA vessels are somewhat leaky. We conclude that PDA IFP is indeed driven by blood pressure, and that fluid exchange between the intravascular and interstitial space in PDA facilitates equilibration of IFP and MVP as in other tumors. The discrepancy between our IFP measurements and those of Provenzano et al. may stem from their use of the piezoelectric-probe technique (Ozerdem and Hargens, 2005), which we believe suffers from artifacts coming from SS. As strong evidence for our hypothesis, Provenzano et al. measured an IFP of 10.4 mmHg (range 8–13 mmHg) in normal mouse pancreata, although normal murine tissues typically have slightly negative IFPs. Ozerdem and Hargens tested this technique against wick-in-needle in a single tumor model in two mice, but they did not carefully test for such artifacts—for example by comparing to wick-in-needle in tissues of varying matrix or cell density. We therefore compared the piezoelectric-probe technique to wick-in-needle in multiple normal murine tissues. We found that the piezoelectric-probe produces significantly higher measurements when compared with wick-in-needle (Figure S1C, D). For example, we measured pancreas IFP as -0.7 mmHg (range -0.9 – -0.5 mmHg) with wick-in-needle, whereas our pancreas measurements with the piezoelectric-probe were 9.8 mmHg (range 8.5–11.3 mmHg). This discrepancy likely occurs because the sensor in the piezoelectric-probe, unlike that in wick-in-needle, directly contacts cells and matrix allowing solid tissue components to contribute to the reading. We conclude that the piezoelectric-probe method developed by Ozerdem and Hargens—and used by Provenzano et al.—measures pressures that are higher than the actual IFP due to artifacts from solid tissue components. As demonstrated here, HA-rich desmoplasia in PDA does not produce unusually high IFP, IFP cannot compress PDA vessels, and the technique Provenzano et al. used to measure IFP actually measures a combination of IFP and SS. Meanwhile, we found that HA increases SS through storage and transmission mechanisms (Stylianopoulos et al., 2012). Thus PEGPH20 likely reduces SS, thereby decompressing vessels. Since IFP cannot compress blood vessels, we propose that the mechanism of vessel decompression by PEGPH20 is solely a reduction in SS. Importantly, therapies that alleviate SS decompress vessels and improve PDA treatment (Chauhan et al., 2013). Thus we concur that PEGPH20 has immense promise for PDA, and we hope that this Correspondence clarifies its mechanism.

The TGF-β pathway is under active consideration as a cancer drug target based on its capacity to promote cancer cell invasion and to create a protumorigenic microenvironment. However, the clinical application of TGF-β inhibitors remains uncertain as genetic studies show a tumor suppressor function of TGF-β in pancreatic cancer and other epithelial malignancies. Here, we used genetically engineered mouse models to investigate the therapeutic impact of global TGF-β inhibition in pancreatic cancer in relation to tumor stage, genetic profile, and concurrent chemotherapy. We found that αvβ6 integrin acted as a key upstream activator of TGF-β in evolving pancreatic cancers. In addition, TGF-β or αvβ6 blockade increased tumor cell proliferation and accelerated both early and later disease stages. These effects were dependent on the presence of Smad4, a central mediator of TGF-β signaling. Therefore, our findings indicate that αvβ6 and TGF-β act in a common tumor suppressor pathway whose pharmacologic inactivation promotes pancreatic cancer progression. Cancer Res; 72(18); 4840–5. ©2012 AACR.

Sustained expression of the histone demethylase, KDM2B (Ndy1/FBXL10/JHDM1B) , bypasses cellular senescence in primary mouse embryonic fibroblasts (MEFs). Here, we show that KDM2B is a conserved regulator of lifespan in multiple primary cell types and defines a program in which this chromatin-modifying enzyme counteracts the senescence-associated down-regulation of the EZH2 histone methyltransferase. Senescence in MEFs epigenetically silences KDM2B and induces the tumor suppressor miRNAs let-7b and miR-101, which target EZH2. Forced expression of KDM2B promotes immortalization by silencing these miRNAs through locus-specific histone H3 K36me2 demethylation, leading to EZH2 up-regulation. Overexpression of let-7b down-regulates EZH2, induces premature senescence, and counteracts immortalization of MEFs driven by KDM2B. The KDM2B-let-7-EZH2 pathway also contributes to the proliferation of immortal Ink4a/Arf null fibroblasts suggesting that, beyond its anti-senescence role in primary cells, this histone-modifying enzyme functions more broadly in the regulation of cellular proliferation. © 2011 by The American Society for Biochemistry and Molecular Biology, Inc.

Activating mutations in K-ras are one of the most common genetic alterations in human lung cancer. To dissect the role of K-ras activation in bronchial epithelial cells during lung tumorigenesis, we created a model of lung adenocarcinoma by generating a conditional mutant mouse with both Clara cell secretory protein (CC10)-Cre recombinase and the Lox-Stop-Lox K-ras(G12D) alleles. The activation of K-ras mutant allele in CC10 positive cells resulted in a progressive phenotype characterized by cellular atypia, adenoma and ultimately adenocarcinoma. Surprisingly, K-ras activation in the bronchiolar epithelium is associated with a robust inflammatory response characterized by an abundant infiltration of alveolar macrophages and neutrophils. These mice displayed early mortality in the setting of this pulmonary inflammatory response with a median survival of 8 weeks. Bronchoalveolar lavage fluid from these mutant mice contained the MIP-2, KC, MCP-1 and LIX chemokines that increased significantly with age. Cell lines derived from these tumors directly produced MIP-2, LIX and KC. This model demonstrates that K-ras activation in the lung induces the elaboration of inflammatory chemokines and provides an excellent means to further study the complex interactions between inflammatory cells, chemokines and tumor progression.