The signature features of pancreatic ductal adenocarcinoma (PDAC) are its fibroinflammatory stroma, poor immune activity and dismal prognosis. We show that acute activation of Myc in indolent PanIN epithelial cells in vivo is, alone, sufficient to trigger immediate release of instructive signals that together coordinate changes in multiple stromal and immune cell types and trigger transition to pancreatic adenocarcinomas that share all the characteristic stromal features of their spontaneous human counterpart. We also demonstrate that this Myc-driven PDAC switch is completely and immediately reversible: Myc deactivation/inhibition triggers meticulous disassembly of advanced PDAC tumor and stroma and concomitant death of tumor cells. Hence, both the formation and deconstruction of the complex PDAC phenotype are continuously dependent on a single, reversible Myc switch. Research.

The Sall2 transcription factor is deregulated in several cancers; however, little is known about its cellular functions, including its target genes. Recently, we demonstrated that p53 directly regulates Sall2 expression under genotoxic stress. Here, we investigated the role of Sall2 in the context of cellular response to genotoxic stress. In addition, we further examined the Sall2-p53 relationship during genotoxic stress in primary mouse embryo fibroblasts (MEFs), which are derived from Sall2 knockout mice separately, or in combination with the p53ERTAM knock-in mice. We found that the levels of Sall2 mRNA and protein are dynamically modulated in response to doxorubicin. At early times of stress, Sall2 is downregulated, but increases under extension of the stress in a p53-independent manner. Based on caspase-3/7 activities, expression of cleaved poly (ADP-ribose) polymerase, expression of cleaved caspase-3 and induction of proapoptotic proteins, Sall2 expression was correlated with cellular apoptosis. Consequently, Sall2−/− MEFs have decreased apoptosis, which relates with increased cell viability in response to doxorubicin. Importantly, Sall2 was required for apoptosis even in the presence of fully activated p53. Searching for putative Sall2 targets that could mediate its role in apoptosis, we identified proapoptotic NOXA/PMAIP1 (phorbol-12-myristate-13-acetate-induced protein 1). We demonstrated that Sall2 positively regulates Noxa promoter activity. Conserved putative Sall2-binding sites at the NOXA promoter were validated in vitro by electrophoretic mobility shift assay and in vivo by ChIP experiments, identifying NOXA as a novel Sall2 target. In agreement, induction of Noxa protein and mRNA in response to doxorubicin was significantly decreased in Sall2−/− MEFs. In addition, studies in leukemia Jurkat T cells support the existence of the Sall2/Noxa axis, and the significance of this axis on the apoptotic response to doxorubicin in cancer cells. Our study highlights the relevance of Sall2 in the apoptotic response to extended genotoxic stress, which is important for understanding its role in normal physiology and disease.

Discute os principais resultados de um projeto de pesquisa que teve como objetivo investigar problemas relativos ao ensino e à aprendizagem da Geometria, enfrentados por professores da rede pública estadual de ensino, bem como por seus alunos de 5ª a 8ª séries. Analisa essencialmente procedimentos metodológicos, fundamentos teóricos e principais resultados, focalizando a origem dos problemas relacionados com o ensino e a aprendizagem da Geometria, as estratégias montadas para enfrentar uma parte desses problemas e as mudanças de concepções e práticas de professores.

The “hallmarks” of pancreatic ductal adenocarcinoma (PDAC) include proliferative, invasive and metastatic tumor cells and an associated dense desmoplasia comprised of fibroblasts, pancreatic stellate cells, extracellular matrix and immune cells. The oncogenically-activated pancreatic epithelium and its associated stroma are obligatorily interdependent, with the resulting inflammatory and immune-suppressive microenvironment contributing greatly to the evolution and maintenance of PDAC. The peculiar pancreas-specific tumor phenotype is a consequence of oncogenes hacking the resident pancreas regenerative program, a tissue specific repair mechanism regulated by discrete super enhancer networks. Defined as genomic regions containing clusters of multiple enhancers, super enhancers play pivotal roles in cell/tissue specification, identity and maintenance. Hence, interfering with such super enhancer driven repair networks should exert a disproportionately disruptive effect on tumor versus normal pancreatic tissue. Novel drugs that directly or indirectly inhibit processes regulating epigenetic status and integrity, including those driven by histone deacetylases, histone methyltransferase and hydroxylases, DNA methyltransferases, various metabolic enzymes, and bromodomain and extra-terminal motif proteins (BETs) have shown the feasibility of disrupting super enhancer-dependent transcription in treating multiple tumor types, including PDAC. The idea that pancreatic adenocarcinomas rely on embedded super enhancer transcriptional mechanism suggests a vulnerability that can be potentially targeted as novel therapies for this intractable disease.

We previously found that the small GTPase Rheb regulates the cell-cycle inhibitor p27KIP1 (p27) in colon cancer cells by a mTORC1-independent mechanism. However, the biological function of the Rheb/p27 axis in cancer cells remains unknown. Here, we show that siRNA-mediated depletion of Rheb decreases survival of human colon cancer cells under serum deprivation. As autophagy can support cell survival, we analyzed the effect of Rheb on this process by detecting the modification of the autophagy marker protein LC3 by western blot and imunofluorescence. We found that Rheb promotes autophagy in several human cancer cell lines under serum deprivation. Accordingly, blocking autophagy inhibited the pro-survival effect of Rheb in colon cancer cells. We then analyzed whether p27 was involved in the biological effect of Rheb. Depletion of p27 inhibited colon cancer cell survival, and Rheb induction of autophagy. These results suggest that p27 has an essential role in the effect of Rheb in response to serum deprivation. In addition, we demonstrated that the role of p27 in autophagy stands on the N-terminal portion of the protein, where the CDK-inhibitory domain is located. Our results indicate that a Rheb/p27 axis accounts for the activation of autophagy that supports cancer cell survival. Our work therefore highlights a biological function of Rheb and prompts the need for future studies to address whether the mTORC1-independent Rheb/p27 axis could contribute to tumorigenesis and/or resistance to mTOR inhibitors.

KEYWORDSMyc, Ras, pancreatic cancer, microenvironment, desmoplasia, immune evasion. fibroinflammatory stroma is a product of complex interplay between tumor cells and adjacent mesenchymal, endothelial, inflammatory and immune cells and is thought to contribute to PDAC therapeutic recalcitrance by impeding vascular perfusion and oxygenation 10,11 .At the molecular level, PDAC is associated with a core of recurring, presumably causal, oncogenic mutations, of which activating mutations in KRas appear to be founder drivers and are present in over 90% of both PanINs and PDAC. Other frequently recurring signature mutations inactivate CDKN2A (90-95%), TP53 (50-84%) or SMAD4/DPC4 (49-55%) and recent, more granular, analyses reveal a plethora of additional sporadic PDAC mutations encompassing great functional diversity 5-7 . As the most commonly recurring oncogenic mutation, many of the canonical features of PDAC are attributed to precocious KRas signaling.

This work analyzes SiO2 and SiO2-CaO glasses incorporated with samarium atoms produced by sol-gel synthesis. The goal is to provide biocompatible and biodegradable radioactive seeds as an alternative to be used in brachytherapy for the treatment of prostate cancer. The chemical and physical characteristics of the obtained glasses were analyzed by energy dispersive x-ray spectroscopy, x-ray diffraction, He picnometry, and nitrogen adsorption analysis. A theoretical analysis of the process of neutron activation of the samples was also conducted through the calculation of the activity of the seeds and the beta- and gamma-ray doses emitted by the seeds. The results demonstrate the incorporation of samarium atoms in the glass matrix. The experimental data coupled with the theoretical studies in neutron activation suggest that it is possible to obtain radioactive seeds with activities equivalent to 125I seeds used in prostatic brachytherapy.

Tuberous sclerosis complex (TSC) disease results from inactivation of the TSC1 or TSC2 gene, and is characterized by benign tumors in several organs. Because TSC tumorigenesis correlates with hyperactivation of mTORC1, current therapies focus on mTORC1 inhibition with rapamycin or its analogs. Rapamycin-induced tumor shrinkage has been reported, but tumor recurrence occurs on withdrawal from rapamycin. Autophagy has been associated with development of TSC tumors and with tumor cell survival during rapamycin treatment. mTORC1 and AMPK directly inhibit and activate autophagy, respectively. AMPK is hyperactivated in TSC cells and tumors, and drives cytoplasmic sequestration of the cell-cycle inhibitor p27KIP (p27). Whether AMPK and p27 are involved in rapamycin-induced autophagy and survival of TSC cells remain unexplored. Here, we show that inhibition of AMPK by compound C or by shRNA-mediated depletion of LKB1 reduces activation of autophagy by rapamycin in Tsc2-null cells. Similarly, shRNA-mediated depletion of p27 inhibited rapamycin-induced autophagy. In support of p27 lying downstream of AMPK on the activation of autophagy in Tsc2-null cells, a p27 mutant that preferentially localizes in the cytosol recovered the effect of rapamycin on autophagy in both p27- and LKB1-depleted cells, but a nuclear p27 mutant was inactive. Finally, we show that p27-dependent activation of autophagy is involved in Tsc2-null cell survival under rapamycin treatment. These results indicate that an AMPK/p27 axis is promoting a survival mechanism that could explain in part the relapse of TSC tumors treated with rapamycin, exposing new avenues for designing more efficient treatments for TSC patients.