A critical event in the pathogenesis of invasive and metastatic cancer is E-cadherin loss of function. Renal clear cell carcinoma (RCC) is characterized by loss of function of the von Hippel-Lindau tumor suppressor (VHL), which negatively regulates hypoxia-inducible factor-1 (HIF-1). Loss of E-cadherin expression and decreased cell-cell adhesion in VHL-null RCC4 cells were corrected by enforced expression of VHL, a dominant-negative HIF-1A mutant, or a short hairpin RNA directed against HIF-1A. In human RCC biopsies, expression of E-cadherin and HIF-1A was mutually exclusive. The expression of mRNAs encoding TCF3, ZFHX1A, and ZFHX1B, which repress E-cadherin gene transcription, was increased in VHL-null RCC4 cells in a HIF-1-dependent manner. Thus, HIF-1 contributes to the epithelial-mesenchymal transition in VHL-null RCC by indirect repression of E-cadherin. (Cancer Res 2006; 66(5): 2725-31)

Although labile iron plays critical roles in diverse biological processes in living cells, the physiological and pathophysiological functions of iron have not been sufficiently explored, partially due to a lack of methods for visualizing intracellular labile iron. In this edge article, we present a novel turn-on fluorescent probe (RhoNox-1) for the selective detection of Fe 2+ based on N-oxide chemistry.Spectroscopic studies combined with DFT calculations and electrochemical studies revealed that fluorescence quenching of RhoNox-1 occurred in physiological conditions, which was attributed to nonradiative deactivation of the excited state of tertiary amine N-oxide substituted xanthene involving a twisted internal charge transfer (TICT) process and partially due to photo-induced electron transfer (PET) from the N-oxide group. RhoNox-1 showed significant enhancement of the fluorescence signal in Fe 2+loaded cells via selective Fe 2+ -mediated deoxygenation of the N-oxide group and also successfully detected basal and endogenous labile Fe 2+ in living cells.

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A simple one-step synthesis of 1,2,4-triazole derivatives is provided by a copper-catalyzed oxidative coupling reaction under an atmosphere of air. The process should consist of sequential N-C and N-N bond-forming copper-catalyzed oxidative coupling reactions. Starting materials and the copper catalyst are readily available and inexpensive. A wide range of functional groups are tolerated to achieve chemical diversity.