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Purpose and methods In human basal-like breast cancer, mutations and deletions in TP53 and BRCA1 are frequent oncogenic events. Thus, we interbred mice expressing the CRE-recombinase with mice harboring loxP sites at TP53 and BRCA1 (K14-Cre; p53f/f Brca1f/f) to test the hypothesis that tissue-specific deletion of TP53 and BRCA1 would give rise to tumors reflective of human basal-like breast cancer. Results In support of our hypothesis, these transgenic mice developed tumors that express basal-like cytokeratins and demonstrated intrinsic gene expression features similar to human basal-like tumors. Array comparative genomic hybridization revealed a striking conservation of copy number alterations between the K14-Cre; p53f/f Brca1f/f mouse model and human basal-like breast cancer. Conserved events included MYC amplification, KRAS amplification, and RB1 loss. Microarray analysis demonstrated that these DNA copy number events also led to corresponding changes in signatures of pathway activation including high proliferation due to RB1 loss. K14-Cre; p53f/f Brca1f/f also matched human basal-like breast cancer for a propensity to have immune cell infiltrates. Given the long latency of K14-Cre; p53f/f Brca1f/f tumors (~ 250 days), we created tumor syngeneic transplant lines, as well as in vitro cell lines, which were tested for sensitivity to carboplatin and paclitaxel. These therapies invoked acute regression, extended overall survival, and resulted in gene expression signatures of an anti-tumor immune response. Conclusion These findings demonstrate that this model is a valuable preclinical resource for the study of human basal-like breast cancer. Electronic supplementary material The online version of this article (10.1007/s10549-018-5061-y) contains supplementary material, which is available to authorized users.

B cell lymphoma and melanoma harbor recurrent mutations in the gene encoding the EZH2 histone methyltransferase (EZH2), but the carcinogenic role of these mutations is unclear. Here we describe a mouse model in which the most common somatic Ezh2 gain-of-function mutation (EZH2(Y646F) in human; Ezh2(Y641F) in mouse) is conditionally expressed. Expression of Ezh2(Y641F) in mouse B cells or melanocytes caused high-penetrance lymphoma or melanoma, respectively. Overexpression of the anti-apoptotic protein Bcl2, but not the oncoprotein Myc, or loss of the tumor suppressor protein p53 (encoded by Trp53 in mice) further accelerated lymphoma progression. Expression of the mutant Braf but not the mutant Nras oncoprotein further accelerated melanoma progression. Although expression of Ezh2(Y641F) globally increased the abundance of trimethylated Lys27 of histone H3 (H3K27me3), it also caused a widespread redistribution of this repressive mark, including a loss of H3K27me3 that was associated with increased transcription at many loci. These results suggest that Ezh2(Y641F) induces lymphoma and melanoma through a vast reorganization of chromatin structure, inducing both repression and activation of polycomb-regulated loci.

Many tumors are dependent on de novo fatty acid synthesis to maintain cell growth. Fatty acid synthase (FASN) catalyzes the final synthetic step of this pathway, and its upregulation is correlated with tumor aggressiveness. The consequences and adaptive responses of acute or chronic inhibition of essential enzymes such as FASN are not fully understood. Herein we identify Fasnall, a thiophenopyrimidine selectively targeting FASN through its co-factor binding sites. Global lipidomics studies with Fasnall showed profound changes in cellular lipid profiles, sharply increasing ceramides, diacylglycerols, and unsaturated fatty acids as well as increasing exogenous palmitate uptake that is deviated more into neutral lipid formation rather than phospholipids. We also showed that the increase in ceramide levels contributes to some extent in the mediation of apoptosis. Consistent with this mechanism of action, Fasnall showed potent anti-tumor activity in the MMTV-Neu model of HER2(+) breast cancer, particularly when combined with carboplatin.

Ovarian clear-cell carcinoma (OCCC) is an aggressive form of ovarian cancer with high ARID1A mutation rates. Here we present a mutant mouse model of OCCC. We find that ARID1A inactivation is not sufficient for tumour formation, but requires concurrent activation of the phosphoinositide 3-kinase catalytic subunit, PIK3CA. Remarkably, the mice develop highly penetrant tumours with OCCC-like histopathology, culminating in haemorrhagic ascites and a median survival period of 7.5 weeks. Therapeutic treatment with the pan-PI3K inhibitor, BKM120, prolongs mouse survival by inhibiting the tumour cell growth. Cross-species gene expression comparisons support a role for IL-6 inflammatory cytokine signalling in OCCC pathogenesis. We further show that ARID1A and PIK3CA mutations cooperate to promote tumour growth through sustained IL-6 overproduction. Our findings establish an epistatic relationship between SWI/SNF chromatin remodelling and PI3K pathway mutations in OCCC and demonstrate that these pathways converge on pro-tumorigenic cytokine signalling. We propose that ARID1A protects against inflammation-driven tumorigenesis.

Large congenital melanocytic nevi (CMN) are at an increased risk of developing melanoma. Several forms of secondary proliferations can arise in congenital nevi on rare occasions. Although some of these closely resemble melanoma both clinically and histologically, metastasis is rare. We used comparative genomic hybridization to analyze chromosomal aberrations in different types of proliferations arising in CMN and compared them to typical congenital nevi, clear-cut melanomas arising in congenital nevi, as well as primary cutaneous melanomas that were not associated with a CMN. Cases of CMN and CMN with secondary proliferations were assigned to six groups according to the predominant histological pattern: group I, bland congenital nevi (n = 6); group II, congenital nevi with foci of increased cellularity (n = 4); group III, CMN with a proliferation simulating superficial spreading melanoma in situ (n = 3); group IV, CMN with a proliferation simulating nodular melanoma (n = 9); group V, proliferating neurocristic hamartoma (n = 1); and group VI, melanoma arising in congenital nevus (n = 6). No aberrations were found in groups I to III, whereas seven of nine cases of group IV, and one of one case of group V, showed aberrations. In group IV six of seven cases with aberrations (86%) showed numerical aberrations of whole chromosomes exclusively. This pattern differed significantly from the findings in melanoma that arose within CMN (n = 6), group VI, or independent of CMN (n = 122) in which only 5% showed numerical changes only. The single case in group V showed aberrations similar to melanoma. The finding of frequent numerical chromosomal aberrations in atypical nodular proliferations arising in CMN identifies these as clonal neoplasms with a genomic instability consistent with a mitotic spindle checkpoint defect. This difference compared to the aberration pattern found in melanoma might explain their more benign clinical behavior and may be of diagnostic value in ambiguous cases.

Sample transport and electrokinetic injection bias are well characterized in capillary electrophoresis and simple microchips, but a thorough understanding of sample transport on devices combining electroosmosis, electrophoresis, and pressure-driven flow is lacking. In this work, we evaluate the effects of electric fields from 0 to 300 V/cm, electrophoretic mobilities from 10(-4) to 10(-6) cm(2)/Vs, and pressure-driven fluid velocities from 50 to 250 μm/s on sample injection in a microfluidic chemical cytometry device. By studying a continuous sample stream, we find that increasing electric field strength and electrophoretic mobility result in improved injection and that COMSOL simulations accurately predict sample transport. The effects of pressure-driven fluid velocity on injection are complex, and relative concentration values lie on a surface defined by pressure-driven flow rates. For high-mobility analytes, this surface is flat, and sample injection is robust despite fluctuations in flow rate. For lower mobility analytes, the surface becomes steeper, and injection depends strongly on pressure-driven flow. These results indicate generally that device design must account for analyte characteristics and specifically that this device is suited to high-mobility analytes. We demonstrate that for a suitable pair of peptides fluctuations in injection volume are correlated; electrokinetic injection bias is minimized; and electrophoretic separation is achieved.

Background: The mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K)/mammalian target of rapamycin (mTOR) pathways are deregulated in many cancers including breast cancer. Additionally, studies have shown that significant crosstalk exists between these pathways; often making single pathway inhibition ineffective. While, combined PI3K/mTOR and MEK inhibition appears highly active in pre-clinical models, the combination has been reported to be toxic in human use. In an effort to produce a more targeted regimen, we examined whether both PI3K and mTOR inhibition are required for pre-clinical anti-tumor efficacy in combination with a MEK inhibitor. Methods: In vivo studies assessed overall survival and best tumor response upon administration of dual PI3K/mTOR (BEZ235 and GSK806) versus allosteric mTOR inhibition (Everolimus) in combination with MEK inhibition (AZD244 and GSK212) in genetically engineered murine models (GEMM) of breast cancer [T11 and C(3)Tag]. Activation and response of the PI3K/mTOR and MEK/ERK pathways to dual PI3K/mTOR, allosteric mTOR inhibition, and MEK inhibition were assessed in vitro in murine cell lines derived from the above GEM models. Results: Single agent regimens of MEK, allosteric mTOR, or dual PI3K/mTOR inhibition were minimally effective in C(3)Tag or T11 tumors in vivo. As previously reported, combined PI3K/mTOR and MEK inhibition showed potent pre-clinical activity in both the T11 and C3Tag models, prolonging overall survival relative to both vehicle or single-agent treated mice. Surprisingly, combinations of MEK inhibitors with allosteric mTOR inhibitors were as active as the MEK/PI3K/mTOR combination. In vitro studies in cell lines derived from these tumor models showed that mTORC1 inhibition, but not PI3K inhibition, resulted in compensatory activation of MEK. Conclusions: Combined targeting of the mTOR and MEK pathways results in improved response and survival in faithful GEM models of breast cancer. The combination of dual PI3K/mTOR catalytic inhibitors with MEK inhibition does not afford benefit over combined allosteric mTOR and MEK inhibition Citation Format: Aleisha M. Smith, Jessie Xiong, Lucas Hunter, Jamie Jordan, Kelly Clark, David B. Darr, Sharpless Norman, Charles M. Perou, William Y. Kim. Inhibition of mTOR, but not PI3K, is required for the anti-tumor efficacy in breast cancer of dual PI3K/mTOR inhibitors given in combination with MEK inhibitors. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2649. doi:10.1158/1538-7445.AM2015-2649

Although effective therapies exist for BRAF-mutant metastatic melanomas (MM) and ER+/PR+/HER2+ breast cancers, fewer options are available for the more aggressive triple negative breast cancers (TNBC) and Ras-mutant MM. Immune infiltration is frequently observed in patient subsets with MM or TNBC. An anti-tumor host immune response may be restrained by the expression of immune checkpoint proteins, such as the programmed death 1 (PD1) protein. We evaluated mDX400, a murine version of the anti-PD-1 antibody MK-3475 that is currently in human clinical trials, in genetically engineered murine models (GEMMs) of melanoma and breast cancer (BC). PD1 antibody was used alone and in combination. Models studied were for basal-like, TNBC (C3TAg), Claudin-Low breast cancer p53null, luminal BC (MMTV-Her2/Neu), RAS-driven melanoma (Tyr-H-Ras and null for Ink4a/Arf (TRIA)) and BRaf-mutant, Pten-deficient melanoma (BRaf/Pten). Mice were housed, treated, and evaluated in the UNC Lineberger Comprehensive Cancer Center Mouse Phase I Unit (MP1U). mDX400 and isotype antibody (10mg/kg IP qw) were supplied by Merck & Co., Inc. Murine cohorts were assessed weekly and therapeutic intervention began once tumors reached 40-64mm3. TNBC models were treated with Carboplatin (C, 50mg/kg IP qwk) in combination with mDX400. mDX400 was administered as a single agent in Melanoma GEMMs. Endpoints were maximal response at ≥21 days and median overall survival (OS). In the C3TAg BC model, mDX400 did not exhibit single-agent activity, but substantial synergy was observed in combination with C [partial response (PR) or CR in 12 of 15 vs. 0 of 19 in non-treated animals, Fisher's exact p=0.006 or vs. C alone 5 of 13 animals, p=0.05] and prolonged OS (41 vs. 28 days in NT, log-rank p=0.006 or C only 28 days, p=0.006) in the C3TAg model. Treatment with single-agent mDX400 induced a marked response in the RAS-driven TRIA melanoma model that is resistant to multiple systemic treatments. mDX400-treated TRIA mice enjoyed an almost tripling of OS [median 56 vs. 21 days, p=0.006]. BRaf/Pten melanomas did not respond to mDX400. Likewise mDX400 plus C provided no benefit to the p53null or MMTV-Her2/Neu BC GEMMs vs. C alone. Our data show differential response of PD-1 antibody therapies to various melanoma and BC models, the latter in combination with C. The responsiveness of a RAS-driven melanoma model to mDX400 is consistent with earlier reports about the clinical benefit of patients with NRAS-mutant melanoma to Ipilimumab, and the lack of PD-L1 expression and immune infiltrates of PTEN-deficient melanomas. At the meeting we will report expression of PD-L1 and other immune checkpoint proteins by cancer cells. The basis whereby carboplatin potentiates the activity of anti-PD1 in TNBC is an area of ongoing study. Citation Format: David Darr, Kelly S. Clark, Joseph H. Phillips, Elaine Pinheiro, Venkataraman Sriram, Jessie Xiong, Jamie Jordan, Norman E. Sharpless, Charles Perou, Stergios Moschos. mDX400, the murine analog against the anti-PD1 antibody MK-347 is active in immunocompetent, autochthonous murine models of melanoma and breast cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5024. doi:10.1158/1538-7445.AM2014-5024

In human cancer, N-RAS mutations resulting in constitutive, oncogenic signaling are predominately localized to codons 12, 13 or 61. Traditionally, activating RAS mutations have been considered oncogenically equivalent, yet recent studies suggest important clinical distinctions between colon cancers containing K-RAS codon 12 vs. codon 13 mutations. More than 20% of human melanomas harbor N-RAS mutations, the vast majority of which target codon 61, as opposed to N-RAS mutations of codon 12 or 13, which are common in other tumor types. To address this issue, we characterized syngeneic knock-in mouse models conditionally expressing either N-RasG12D or N-RasQ61R under the control of the endogenous locus. In primary melanocyte cultures, activation of either N-Ras allele reduced cellular proliferation even in the presence of concomitant p16INK4a deletion. Correspondingly, melanocyte-specific N-RasG12D expression combined with p16INK4a loss failed to efficiently promote melanoma formation in mice. In contrast, melanocyte-specific N-RasQ61R induction readily combined with p16INK4a loss to promote melanoma formation in vivo with short latency and high penetrance. These results provide a first murine model of melanoma featuring knock-in N-Ras mutationQ61R, and suggest that the preference for codon 61 mutations in human tumors is conserved in mice. Citation Format: Christin Burd, William R. Jeck, Kailing Fu, Kelly S. Clark, Jessie C. Xiong, George P. Souroullas, Norman E. Sharpless. Differential oncogenicity of N-RAS mutations in melanoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1087. doi:10.1158/1538-7445.AM2013-1087

Many cytokines signal through different cell-surface receptors to activate the transcription factor NF-kappaB. Members of the TRAF protein family have been implicated in the activation of NF-kappaB by the tumour-necrosis factor (TNF)-receptor superfamily. Here we report the identification of a new TRAF family member, designated TRAF6. When overexpressed in human 293 cells, TRAF6 activates NF-kappaB. A dominant-negative mutant of TRAF6 inhibits NF-kappaB activation signalled by interleukin-1 (IL-1) but not by TNF. IL-1 treatment of 293 cells induces the association of TRAF6 with IRAK, a serine/threonine kinase that is rapidly recruited to the IL-1 receptor after IL-1 induction. These findings indicate that TRAF proteins may function as signal transducers for distinct receptor families and that TRAF6 participates in IL-1 signalling.

Tumor necrosis factor (TNF) receptor-associated factor (TRAF) proteins associate with and transduce signals from TNF receptor 2, CD40, and presumably other members of the TNF receptor superfamily. TRAF2 is required for CD40- and TNF-mediated activation of the transcription factor NF-kappa B. Here we describe the isolation and characterization of a novel TRAF-interacting protein, I-TRAF, that binds to the conserved TRAF-C domain of the three known TRAFs. Overexpression of I-TRAF inhibits TRAF2-mediated NF-kappa B activation signaled by CD40 and both TNF receptors. Thus, I-TRAF appears as a natural regulator of TRAF function that may act by maintaining TRAFs in a latent state.

Many diverse activities of tumor necrosis factor (TNF) are signaled through TNF receptor 1 (TNFR1). We have identified a novel 34 kDa protein, designated TRADD, that specifically interacts with an intracellular domain of TNFR1 known to be essential for mediating programmed cell death. Overexpression of TRADD leads to two major TNF-induced responses, apoptosis and activation of NF-kappa B. The C-terminal 118 amino acids of TRADD are sufficient to trigger both of these activities and likewise sufficient for interaction with the death domain of TNFR1. TRADD-mediated cell death can be suppressed by the crmA gene, which encodes a specific inhibitor of the interleukin-1 beta-converting enzyme. However, NF-kappa B activation by TRADD is not inhibited by crmA expression, demonstrating that the signaling pathways for TNF-induced cell death and NF-kappa B activation are distinct.