Small cell lung cancer (SCLC) is an aggressive neuroendocrine subtype of lung cancer with high mortality. We used a systematic drug-repositioning bioinformatics approach querying a large compendium of gene expression profiles to identify candidate FDA-approved drugs to treat SCLC. We found that tricyclic antidepressants and related molecules potently induce apoptosis in both chemonaïve and chemoresistant SCLC cells in culture, in mouse and human SCLC tumors transplanted into immunocompromised mice, and in endogenous tumors from a mouse model for human SCLC. The candidate drugs activate stress pathways and induce cell death in SCLC cells, at least in part by disrupting autocrine survival signals involving neurotransmitters and their G protein-coupled receptors. The candidate drugs inhibit the growth of other neuroendocrine tumors, including pancreatic neuroendocrine tumors and Merkel cell carcinoma. These experiments identify novel targeted strategies that can be rapidly evaluated in patients with neuroendocrine tumors through the repurposing of approved drugs.

Purpose: As chemotherapy and molecular therapy improve the systemic survival of breast cancer patients, the incidence of brain metastases increases. Few therapeutic strategies exist for the treatment of brain metastases because the blood-brain barrier severely limits drug access. We report the pharmacokinetic, efficacy, and mechanism of action studies for the histone deactylase inhibitor vorinostat (suberoylanilide hydroxamic acid) in a preclinical model of brain metastasis of triple-negative breast cancer. Experimental Design: The 231-BR brain trophic subline of the MDA-MB-231 human breast cancer cell line was injected into immunocompromised mice for pharmacokinetic and metastasis studies. Pharmacodynamic studies compared histone acetylation, apoptosis, proliferation, and DNA damage in vitro and in vivo. Results: Following systemic administration, uptake of [ 14 C]vorinostat was significant into normal rodent brain and accumulation was up to 3-fold higher in a proportion of metastases formed by 231-BR cells. Vorinostat prevented the development of 231-BR micrometastases by 28% (P = 0.017) and large metastases by 62% (P < 0.0001) compared with vehicle-treated mice when treatment was initiated on day 3 post-injection. The inhibitory activity of vorinostat as a single agent was linked to a novel function in vivo: induction of DNA double-strand breaks associated with the down-regulation of the DNA repair gene Rad52. Conclusions:We report the first preclinical data for the prevention of brain metastasis of triple-negative breast cancer. Vorinostat is brain permeable and can prevent the formation of brain metastases by 62%. Its mechanism of action involves the induction of DNA double-strand breaks, suggesting rational combinations with DNA active drugs or radiation. (Clin Cancer Res 2009;15(19):6148-57) Significant advances have been made in the treatment of primary breast cancer; one of the unfortunate complications of this progress is an increase in the incidence of brain metastases (reviewed in refs. 1, 2). Combinations of cytotoxic and targeted therapies have afforded metastatic breast cancer patients' clinical responses or stable disease, but the poor penetration of these drugs into the brain and leptomeninges creates a "sanctuary site" for recurrence. With an increased number of metastatic breast cancer patients having stable disease or responding to treatment systemically when they develop brain metastases,

Amplification of chromosomal region 8p11-12 is a frequent genetic alteration implicated in the etiology of lung squamous cell carcinoma (LUSC) 1 - 3 . FGFR1 (fibroblast growth factor receptor 1) is the main candidate driver within this region 4 . However, clinical trials evaluating FGFR1 inhibition as a targeted therapy have been unsuccessful 5 . Here we identify the H3K36 methyltransferase NSD3 ( n uclear receptor binding S ET d omain protein 3 ), an 8p11-12-localized gene, as a key regulator of LUSC tumorigenesis. In contrast to other 8p11-12 candidate LUSC drivers, increased NSD3 expression strongly correlates with its gene amplification. Ablation of NSD3 , but not FGFR1 , attenuates tumor growth and extends survival in a potent LUSC mouse model. We identify NSD3 T1232A as an LUSC-associated variant that increases H3K36 dimethylation (H3K36me2) catalytic activity in vitro and in vivo . Structural dynamic analyses reveal that the T1232A substitution elicits localized mobility changes throughout NSD3’s catalytic domain to relieve auto-inhibition and increase H3 substrate accessibility. NSD3 T1232A expression in vivo accelerates tumorigenesis and decreases overall survival in LUSC mouse models. Pathologic H3K36me2 generation by NSD3 T1232A rewires the chromatin landscape to promote oncogenic gene expression programming. Further, NSD3’s catalytic activity promotes human tracheobronchial cell transformation and xenograft growth of human 8p11-12-amplified LUSC cell lines. NSD3 depletion in patient-derived xenografts (PDXs) from primary LUSC harboring NSD3 amplification or the NSD3 T1232A variant attenuates neoplastic growth. Finally, NSD3-regulated LUSC PDXs are markedly sensitive to bromodomain inhibition (BETi). Together, our work identifies NSD3 as a principal 8p11-12 amplicon-associated oncogenic driver in LUSC and suggests that NSD3-dependency renders LUSC therapeutically vulnerable to BETi.

Pancreatic ductal adenocarcinoma (PDAC) is a lethal form of cancer with few therapeutic options. We found that levels of the lysine methyltransferase SMYD2 (SET and MYND domain 2) are elevated in PDAC and that genetic and pharmacological inhibition of SMYD2 restricts PDAC growth. We further identified the stress response kinase MAPKAPK3 (MK3) as a new physiologic substrate of SMYD2 in PDAC cells. Inhibition of MAPKAPK3 impedes PDAC growth, identifying a potential new kinase target in PDAC. Finally, we show that inhibition of SMYD2 cooperates with standard chemotherapy to treat PDAC cells and tumors. These findings uncover a pivotal role for SMYD2 in promoting pancreatic cancer.

Highlights d SETD5 is an epigenetic driver of pancreatic cancer resistance to MEK1/2 inhibition d SETD5 has no intrinsic methylation activity on histones, including at H3 lysine 36 d A SETD5 co-repressor complex regulates a network of drug resistance pathways d Co-targeting of MEK1/2 and the SETD5 complex results in sustained tumor inhibition

BARD1 and RAD51 are frequently overexpressed in brain metastases from breast cancer and may constitute a mechanism to overcome reactive oxygen species-mediated genotoxic stress in the metastatic brain.

The cellular turnover of adult tissues and injury-induced repair proceed through an exquisite integration of proliferation, differentiation, and survival signals that involve stem/progenitor cell populations, their progeny, and differentiated tissues. GATA factors are DNA binding proteins that control stem cells and the development of tissues by activating or repressing transcription. Here we examined the role of GATA transcription factors in Schmidtea mediterranea, a freshwater planarian that provides an excellent model to investigate gene function in adult stem cells, regeneration, and differentiation. Smed-gata4/5/6, the homolog of the three mammalian GATA-4,-5,-6 factors is expressed at high levels in differentiated gut cells but also at lower levels in neoblast populations, the planarian stem cells. Smed-gata4/5/6 knock-down results in broad differentiation defects, especially in response to injury. These defects are not restricted to the intestinal lineage. In particular, at late time points during the response to injury, loss of Smed-gata4/5/6 leads to decreased neoblast proliferation and to gene expression changes in several neoblast subpopulations. Thus, Smed-gata4/5/6 plays a key evolutionary conserved role in intestinal differentiation in planarians. These data further support a model in which defects in the intestinal lineage can indirectly affect other differentiation pathways in planarians.

Study approval. All experiments in mice were performed according to the MD Anderson Cancer Center Institutional Animal Care and Use Committee (IACUC, protocol 00001636), UCSF Committee on Animal Care (APLAC), and the University of Navarra Ethical Committee on Animal Research (CEEA, protocol 068-13). Regarding human data, only normalized/processed data of coded clinical information were made available to this study to preserve patients' anonymity.