Elevation of L-2-hydroxylgutarate (L-2-HG) in renal cell carcinoma (RCC) is due in part to reduced expression of L-2-HG dehydrogenase (L2HGDH). However, the contribution of L-2-HG to renal carcinogenesis and insight into the biochemistry and targets of this small molecule remains to be elucidated. Genetic and pharmacologic approaches to modulate L-2-HG levels were assessed for effects on and phenotypes. Metabolomics was used to dissect the biochemical mechanisms that promote L-2-HG accumulation in RCC cells. Transcriptomic analysis was utilized to identify relevant targets of L-2-HG. Finally, bioinformatic and metabolomic analyses were used to assess the L-2-HG/L2HGDH axis as a function of patient outcome and cancer progression. L2HGDH suppresses both cell migration and tumor growth and these effects are mediated by L2HGDH's catalytic activity. Biochemical studies indicate that glutamine is the predominant carbon source for L-2-HG via the activity of malate dehydrogenase 2 (MDH2). Inhibition of the glutamine-MDH2 axis suppresses phenotypes in an L-2-HG-dependent manner. Moreover, growth of RCC cells with basal elevation of L-2-HG is suppressed by glutaminase inhibition. Transcriptomic and functional analyses demonstrate that the histone demethylase KDM6A is a target of L-2-HG in RCC. Finally, increased L-2-HG levels, copy loss, and lower L2HGDH expression are associated with tumor progression and/or worsened prognosis in patients with RCC. Collectively, our studies provide biochemical and mechanistic insight into the biology of this small molecule and provide new opportunities for treating L-2-HG-driven kidney cancers.

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The Cancer Genome Atlas (TCGA) and other large-scale genomic data pipelines have been integral to the current understanding of the molecular events underlying renal cell carcinoma (RCC). These data networks have focused mostly on primary RCC, which often demonstrates indolent behavior. However, metastatic disease is the major cause of mortality associated with RCC and data sets examining metastatic tumors are sparse. Therefore, a more comprehensive analysis of gene expression and DNA methylome profiling of metastatic RCC in addition to primary RCC and normal kidney was performed. Integrative analysis of the methylome and transcriptome identified over 30 RCC-specific genes whose mRNA expression inversely correlated with promoter methylation, including several known targets of hypoxia inducible factors. Notably, genes encoding several metabolism-related proteins were identified as differentially regulated via methylation including hexokinase 2, aldolase C, stearoyl-CoA desaturase, and estrogen-related receptor-γ (ESRRG), which has a known role in the regulation of nuclear-encoded mitochondrial metabolism genes. Several gene expression changes could portend prognosis in the TCGA cohort. Mechanistically, ESRRG loss occurs via DNA methylation and histone repressive silencing mediated by the polycomb repressor complex 2. Restoration of ESRRG in RCC lines suppresses migratory and invasive phenotypes independently of its canonical role in mitochondrial metabolism. Collectively, these data provide significant insight into the biology of aggressive RCC and demonstrate a novel role for DNA methylation in the promotion of HIF signaling and invasive phenotypes in renal cancer.

Nanocrystals having single-band red emission under near-infrared (NIR) excitation through the upconversion process offer great advantages in terms of enhanced cellular imaging in in vitro and in vivo experiments in the biological window (600−900 nm), as a security ink, in photothermal therapy (PTT), in photodynamic therapy (PDT), and so forth but are challenging for materials scientists. In this work, we report for the first time the preparation of a super bright red emitter at 655 nm from monodispersed NaErF 4 :0.5%Tm@ NaYF 4 :20%Yb nanocrystals (core@active shell). This phosphor exhibits 35 times stronger photoluminescence as compared to NaErF 4 :0.5%Tm@NaYF 4 (core@inactive shell). Here, an Er 3+ -enriched host matrix works simultaneously as an activator and a sensitizer under NIR excitation. Upconversion red emission at 655 nm arises due to the electronic transition of Er 3+ via the involvement of a three-photon absorption (expected to be a two-photon absorption), which has been confirmed via a power-dependent luminescence study. Tm 3+ ions incorporated into the core with the active shell act as trapping centers, which promote the red band emission via the back-energy transfer process. Moreover, the active shell containing Yb 3+ ions efficiently transfers the energy to the Er 3+ -enriched core, which suppresses the nonradiative channel rate, and Tm 3+ ions act as trapping centers, which reduce the luminescence quenching via reduction of energy migration to the surface of the host lattice. Also, we have shown the potential applications of these nanocrystals: cellular imaging through downconversion and upconversion processes and security ink.

Recently we have reported that age-dependent decline in antioxidant levels accelerated apoptosis and skeletal muscle degeneration. Here, we demonstrate genetic ablation of the master cytoprotective transcription factor, nuclear factor (erythroid-derived-2)-like 2 (Nrf2), aggravates cardiotoxin (CTX)-induced tibialis anterior (TA) muscle damage. Disruption of Nrf2 signaling sustained the CTX-induced burden of reactive oxygen species together with compromised expression of antioxidant genes and proteins. Transcript/protein expression of phenotypic markers of muscle differentiation, namely paired box 7 (satellite cell) and early myogenic differentiation and terminal differentiation (myogenin and myosin heavy chain 2) were increased on d 2 and 4 postinjury but later returned to baseline levels on d 8 and 15 in wild-type (WT) mice. In contrast, these responses were persistently augmented in Nrf2-null mice suggesting that regulation of the regeneration-related signaling mechanisms require Nrf2 for normal functioning. Furthermore, Nrf2-null mice displayed slower regeneration marked by dysregulation of embryonic myosin heavy chain temporal expression. Histologic observations illustrated that Nrf2-null mice displayed smaller, immature TA muscle fibers compared with WT counterparts on d 15 after CTX injury. Improvement in TA muscle morphology and gain in muscle mass evident in the WT mice was not noticeable in the Nrf2-null animals. Taken together these data show that the satellite cell activation, proliferation, and differentiation requires a functional Nrf2 system for effective healing following injury.-Shelar, S. B., Narasimhan, M., Shanmugam, G., Litovsky, S. H., Gounder, S. S., Karan, G., Arulvasu, C., Kensler, T. W., Hoidal, J. R., Darley-Usmar, V. M., Rajasekaran, N. S. Disruption of nuclear factor (erythroid-derived-2)-like 2 antioxidant signaling: a mechanism for impaired activation of stem cells and delayed regeneration of skeletal muscle.