EYA proteins (EYA1-4) are critical developmental transcriptional cofactors that contain an EYA domain (ED) harboring Tyr phosphatase activity. EYA proteins are largely downregulated after embryogenesis but are reexpressed in cancers, and their Tyr phosphatase activity plays an important role in the DNA damage response and tumor progression. We previously identified a class of small-molecule allosteric inhibitors that specifically inhibit the Tyr phosphatase activity of EYA2. Herein, we determined the crystal structure of the EYA2 ED in complex with NCGC00249987 (a representative compound in this class), revealing that it binds to an induced pocket distant from the active site. NCGC00249987 binding leads to a conformational change of the active site that is unfavorable for Mg 2þ binding, thereby inhibiting EYA2's Tyr phosphatase activity. We demonstrate, using genetic muta-tions, that migration, invadopodia formation, and invasion of lung adenocarcinoma cells are dependent on EYA2 Tyr phosphatase activity, whereas growth and survival are not. Further, we demonstrate that NCGC00249987 specifically targets migration, invadopodia formation, and invasion of lung cancer cells, but that it does not inhibit cell growth or survival. The compound has no effect on lung cancer cells carrying an EYA2 F290Y mutant that abolishes compound binding, indicating that NCGC00249987 is on target in lung cancer cells. These data suggest that the NCGC00249987 allosteric inhibitor can be used as a chemical probe to study the function of the EYA2 Tyr phosphatase activity in cells and may have the potential to be developed into an antimetastatic agent for cancers reliant on EYA2's Tyr phosphatase activity.

Tumor initiating cells (TIC) represent a subset of tumor cells with increased self-renewal capability. TICs display resistance to frontline cancer treatment and retain the ability to repopulate a tumor after therapy, leading to cancer relapse. NOTCH signaling has been identified as an important driver of the TIC population, yet mechanisms governing regulation of this pathway in cancer remain to be fully elucidated. Here, we identify a novel mechanism of NOTCH regulation and TIC induction in breast cancer, via the miR-106b-25 miRNA cluster. We show that the miR-106b-25 cluster upregulates NOTCH1 in multiple breast cancer cell lines, representing both estrogen receptor (ER+) and triple negative breast cancer (TNBC), through direct repression of the E3 ubiquitin ligase, NEDD4L. We further show that upregulation of NOTCH1 is necessary for TIC induction downstream of miR-106b-25 in both ER+ and TNBC breast cancer cells, and that re-expression of NEDD4L is sufficient to reverse miR106b-25-mediated NOTCH1 upregulation and TIC induction. Importantly, we demonstrate a significant positive correlation between miR-106b-25 and NOTCH1 protein, yet a significant inverse correlation between miR-106b-25 and NEDD4L mRNA in human breast cancer, suggesting a critical role for the miR106b-25/NEDD4L/NOTCH1 axis in the disease. Further, we show for the first time that NEDD4L expression alone is significantly associated with a better relapse free prognosis for breast cancer patients. These data expand our knowledge of the mechanisms underlying NOTCH activation and TIC induction in breast cancer, and may provide new avenues for the development of therapies targeting this resistant subset of tumor cells.

Infection of human neuronsin vitrowith varicella-zoster virus (VZV) at a low multiplicity of infection does not result in a cytopathic effect (CPE) within 14 days postinfection (dpi), despite production of infectious virus. We showed that by 28 dpi a CPE ultimately developed in infected neurons and that interferon gamma inhibited not only the CPE but also VZV DNA accumulation, transcription, and virus production, thereby prolonging the life of VZV-infected neurons.

TNF-related apoptosis inducing ligand (TRAIL) is a potent death-inducing ligand that mediates apoptosis through the extrinsic pathway and serves as an important endogenous tumor suppressor mechanism. Because tumor cells are often killed by TRAIL and normal cells are not, drugs that activate the TRAIL pathway have been thought to have potential clinical value. However, to date, most TRAIL-related clinical trials have largely failed due to the tumor cells having intrinsic or acquired resistance to TRAIL-induced apoptosis. Previous studies to identify resistance mechanisms have focused on targeted analysis of the canonical apoptosis pathway and other known regulators of TRAIL receptor signaling. To identify novel mechanisms of TRAIL resistance in an unbiased way, we performed a genome wide shRNA screen for genes that regulate TRAIL sensitivity in sub-lines that had been selected for acquired TRAIL resistance. This screen identified previously unknown mediators of TRAIL resistance including Angiotensin II Receptor 2, Crk-like protein, T-Box Transcription Factor 2 and solute carrier family 26 member 2 (SLC26A2). SLC26A2 downregulates the TRAIL receptors, DR4 and DR5, and this downregulation is associated with resistance to TRAIL. Its expression is high in numerous tumor types compared to normal cells, and in breast cancer, SLC26A2 is associated with a significant decrease in relapse free survival.