ARID1A regulates expression of SOX9, activation of the mTOR pathway, and differentiation of PDCs. ARID1A inhibits formation of PDACs from IPMNs in mice with pancreatic expression of activated KRAS and is down-regulated in IPMN and PDAC tissues from patients.

Setdb1 p53 P ancreatic ductal adenocarcinoma (PDAC) is one of the most dismal malignancies, with an extremely poor prognosis. 1 In order to further improve the prognosis, it is crucial to elucidate the molecular mechanisms underlying PDAC initiation and progression. Recent studies have revealed that epigenetic abnormalities exhibit a great influence on the characteristics of cancer development in addition to genetic abnormalities. 2-4 One form of epigenetic regulation, known as histone modification, contributes to tumorigenesis by affecting the expression of oncogenes/tumor suppressor genes. In fact, previous reports have shown that histone methyltransferases suppress pancreatic cancer by regulating glucose/fatty acid metabolism and promoting pancreatic regeneration. 5,6 Setdb1 serves as a histone 3 lysine 9 trimethyltransferase. Trimethylation of histone 3 lysine 9 (H3K9me3) is a repressive chromatin modification. 7 Setdb1 plays different functional roles through gene silencing. It helps to control heterochromatin formation 8 and contributes to stem cell maintenance, 9 embryonic development, and endogenous proviral silencing. 10 Recently, an in vivo study revealed that the amplification of Setdb1 accelerates the development of melanoma, 11 and SETDB1 has been shown to promote tumorigenesis in various human cancers, including lung, 12 liver, 13,14 and breast cancers. 15 Furthermore, a wholeexome sequencing study revealed a copy number amplification mutation of SETDB1 in PDAC patients. 16 These findings indicate a role of Setdb1 in PDAC initiation and progression. However, the functional role of Setdb1 in PDAC remains elusive. Therefore, in this study, we aimed to investigate the impact of Setdb1 deletion on Kras-induced pancreatic tumorigenesis and elucidate the in vivo role of Setdb1 in PDAC formation in mouse models. Materials and Methods Mice Experimental animals were generated by crossing Ptf1a Cre (gift from Y. Kawaguchi, Kyoto University, Kyoto, Japan), 17 Kras G12D (gift from D. Tuveson, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY), 18 Setdb1 flox (gift from Y. Shinkai, Riken, Saitama, Japan), 10 and p53 flox (purchase from Jackson Laboratory, Bar Harbor, ME; JAX strain 008462). Acute pancreatitis was induced at 6 weeks of age by injecting cerulein (2 mg/injection diluted in phosphate-buffered saline; Sigma-Aldrich, St Louis, MO) intraperitoneally on 2 consecutive days once every hour for 8 hours each day. 19 Clinical Samples Forty-eight surgically resected specimens of pancreatic cancer tissues were obtained from patients who had been admitted to Kyoto University Hospital. Written informed consent was obtained from all patients and the protocol was approved by the Ethics Committee of Kyoto University.

Adverse prognostic impact of KIT mutations in childhood CBF-AML: the results of the Japanese pediatric leukemia/lymphoma study group AML-05 trial

Tumor cells capable of self-renewal and continuous production of progeny cells are called tumor stem cells (TSCs) and are considered to be potential therapeutic targets. However, the mechanisms underlying the survival and function of TSCs are not fully understood. We previously reported that chromatin remodeling regulator Brg1 is essential for intestinal stem cells in mice and Dclk1 is an intestinal TSC marker. In this study, we investigated the role of Brg1 in Dclk1 + intestinal tumor cells for the maintenance of intestinal tumors in mice. Specific ablation of Brg1 in Dclk1 + intestinal tumor cells reduced intestinal tumors in Apc Min mice, and continuous ablation of Brg1 maintained the reduction of intestinal tumors. Lineage tracing in the context of Brg1 ablation in Dclk1 + intestinal tumor cells revealed that Brg1-null Dclk1 + intestinal tumor cells did not give rise to their descendent tumor cells, indicating that Brg1 is essential for the self-renewal of Dclk1 + intestinal tumor cells. Five days after Brg1 ablation, we observed increased apoptosis in Dclk1 + tumor cells. Furthermore, Brg1 was crucial for the stemness of intestinal tumor cells in a spheroid culture system. BRG1 knockdown also impaired cell proliferation and increased apoptosis in human colorectal cancer (CRC) cells. Microarray analysis revealed that apoptosis-related genes were upregulated and stem cell-related genes were downregulated in human CRC cells by BRG1 suppression. Consistently, high BRG1 expression correlated with poor disease-specific survival in human CRC patients. These data indicate that Brg1 plays a crucial role in intestinal TSCs in mice by inhibiting apoptosis and is critical for cell survival and stem cell features in human CRC cells. Thus, BRG1 represents a new therapeutic target for human CRC.

No abstract