Ninel Azoitei

The transcription factor NF-kappaB is activated in a range of human cancers and is thought to promote tumorigenesis, mainly due to its ability to protect transformed cells from apoptosis. To investigate the role of NF-kappaB in epithelial plasticity and metastasis, we utilized a well-characterized in vitro/in vivo model of mammary carcinogenesis that depends on the collaboration of the Ha-Ras oncoprotein and TGF-beta. We show here that the IKK-2/IkappaBalpha/NF-kappaB pathway is required for the induction and maintenance of epithelial-mesenchymal transition (EMT). Inhibition of NF-kappaB signaling prevented EMT in Ras-transformed epithelial cells, while activation of this pathway promoted the transition to a mesenchymal phenotype even in the absence of TGF-beta. Furthermore, inhibition of NF-kappaB activity in mesenchymal cells caused a reversal of EMT, suggesting that NF-kappaB is essential for both the induction and maintenance of EMT. In line with the importance of EMT for invasion, blocking of NF-kappaB activity abrogated the metastatic potential of mammary epithelial cells in a mouse model system. Collectively, these data provide evidence of an essential role for NF-kappaB during distinct steps of breast cancer progression and suggest that the cooperation of Ras- and TGF-beta-dependent signaling pathways in late-stage tumorigenesis depends critically on NF-kappaB activity.

The transcription factor NF-B is activated in a range of human cancers and is thought to promote tumorigenesis, mainly due to its ability to protect transformed cells from apoptosis. To investigate the role of NF-B in epithelial plasticity and metastasis, we utilized a well-characterized in vitro/in vivo model of mammary carcinogenesis that depends on the collaboration of the Ha-Ras oncoprotein and TGF-. We show here that the IKK-2/IB/NF-B pathway is required for the induction and maintenance of epithelial-mesenchymal transition (EMT). Inhibition of NF-B signaling prevented EMT in Ras-transformed epithelial cells, while activation of this pathway promoted the transition to a mesenchymal phenotype even in the absence of TGF-. Furthermore, inhibition of NF-B activity in mesenchymal cells caused a reversal of EMT, suggesting that NF-B is essential for both the induction and maintenance of EMT. In line with the importance of EMT for invasion, blocking of NF-B activity abrogated the metastatic potential of mammary epithelial cells in a mouse model system. Collectively, these data provide evidence of an essential role for NF-B during distinct steps of breast cancer progression and suggest that the cooperation of Ras-and TGF--dependent signaling pathways in late-stage tumorigenesis depends critically on NF-B activity.

BACKGROUND: Initially identified as a molecule that regulates the final step of glycolysis, the M2 isoform of pyruvate kinase (PKM2) was recently reported to have a central role in the metabolic reprogramming of cancer cells as well as participating in cell cycle progression and gene transcription. Despite intensive efforts, the intricate molecular mechanisms through which PKM2 regulates tumor progression remain elusive. METHODS: The proliferation and apoptosis of various pancreatic cancer cells using lentiviral-mediated PKM2 abrogation were assessed in vitro via Western blot and flow cytometric assay while the in vivo experiments involved tumor xenograft on chicken chorionallantoic membranes and immunohistochemistry on human tissue specimens. In order to decipher the molecular mechanism of HIF-1α and p65/RelA regulation by PKM2 in cancer cells cultivated in hypoxic atmosphere or normoxia we involved various biochemical assays such as Western blotting, immunoprecipitation, reporter gene assay and ELISA. RESULTS: Strong expression of PKM2 was observed in 68 % of human pancreatic adenocarcinoma specimens and almost all analyzed pancreatic cancer cell lines. Abrogation of PKM2 resulted in impaired proliferation and augmented apoptosis in vitro as well as impaired tumor growth and decreased blood vessel formation in vivo. Furthermore, deletion of PKM2 negatively impacted hypoxia-induced HIF-1α accumulation and promoter activity ultimately resulting in impaired secretion of VEGF. CONCLUSIONS: Our study suggests that in hypoxic pancreatic tumors PKM2 interferes both with NF-κB/p65 and HIF-1α activation that ultimately triggers VEGF-A secretion and subsequent blood vessel formation.

Next-generation sequencing has become a cornerstone of therapy guidance in cancer precision medicine and an indispensable research tool in translational oncology. Its rapidly increasing use during the last decade has expanded the options for targeted tumor therapies, and molecular tumor boards have grown accordingly. However, with increasing detection of genetic alterations, their interpretation has become more complex and error-prone, potentially introducing biases and reducing benefits in clinical practice. To facilitate interdisciplinary discussions of genetic alterations for treatment stratification between pathologists, oncologists, bioinformaticians, genetic counselors and medical scientists in specialized molecular tumor boards, several systems for the classification of variants detected by large-scale sequencing have been proposed. We review three recent and commonly applied classifications and discuss their individual strengths and weaknesses. Comparison of the classifications underlines the need for a clinically useful and universally applicable variant reporting system, which will be instrumental for efficient decision making based on sequencing analysis in oncology. Integrating these data, we propose a generalizable classification concept featuring a conservative and a more progressive scheme, which can be readily applied in a clinical setting.

Abstract Pancreatic ductal adenocarcinomas (PDAC) harbor recurrent functional mutations of the master DNA damage response kinase ATM, which has been shown to accelerate tumorigenesis and epithelial–mesenchymal transition. To study how ATM deficiency affects genome integrity in this setting, we evaluated the molecular and functional effects of conditional Atm deletion in a mouse model of PDAC. ATM deficiency was associated with increased mitotic defects, recurrent genomic rearrangements, and deregulated DNA integrity checkpoints, reminiscent of human PDAC. We hypothesized that altered genome integrity might allow synthetic lethality-based options for targeted therapeutic intervention. Supporting this possibility, we found that the PARP inhibitor olaparib or ATR inhibitors reduced the viability of PDAC cells in vitro and in vivo associated with a genotype-selective increase in apoptosis. Overall, our results offered a preclinical mechanistic rationale for the use of PARP and ATR inhibitors to improve treatment of ATM-mutant PDAC. Cancer Res; 77(20); 5576–90. ©2017 AACR.