Focal adhesion kinase-promoted tumor glucose metabolism is associated with a shift of mitochondrial respiration to glycolysis.

Cancer cells often gains a growth advantage by taking up glucose at a high rate and undergoing aerobic glycolysis through intrinsic cellular factors that reprogram glucose metabolism. Focal adhesion kinase (FAK), a key transmitter of growth factor and anchorage stimulation, is aberrantly overexpressed or activated in most solid tumors, including pancreatic ductal adenocarcinomas (PDACs). We determined whether FAK can act as an intrinsic driver to promote aerobic glycolysis and tumorigenesis. FAK inhibition decreases and overexpression increases intracellular glucose levels during unfavorable conditions, including growth factor deficiency and cell detachment. Amplex glucose assay, fluorescence and carbon-13 tracing studies demonstrate that FAK promotes glucose consumption and glucose-to-lactate conversion. Extracellular flux analysis indicates that FAK enhances glycolysis and decreases mitochondrial respiration. FAK increases key glycolytic proteins, including enolase, pyruvate kinase M2 (PKM2), lactate dehydrogenase and monocarboxylate transporter. Furthermore, active/tyrosine-phosphorylated FAK directly binds to PKM2 and promotes PKM2-mediated glycolysis. On the other hand, FAK-decreased levels of mitochondrial complex I can result in reduced oxidative phosphorylation (OXPHOS). Attenuation of FAK-enhanced glycolysis re-sensitizes cancer cells to growth factor withdrawal, decreases cell viability and reduces growth of tumor xenografts. These observations, for the first time, establish a vital role of FAK in cancer glucose metabolism through alterations in the OXPHOS-to-glycolysis balance. Broadly targeting the common phenotype of aerobic glycolysis and more specifically FAK-reprogrammed glucose metabolism will disrupt the bioenergetic and biosynthetic supply for uncontrolled growth of tumors, particularly glycolytic PDAC.

Loss of type III transforming growth factor-beta receptor expression is due to methylation silencing of the transcription factor GATA3 in renal cell carcinoma.

Loss of transforming growth factor-beta receptor III (TbetaRIII) correlates with loss of transforming growth factor-beta (TGF-beta) responsiveness and suggests a role for dysregulated TGF-beta signaling in clear cell renal cell carcinoma (ccRCC) progression and metastasis. Here we identify that for all stages of ccRCC TbetaRIII expression is downregulated in patient-matched tissue samples and cell lines. We find that this loss of expression is not due to methylation of the gene and we define GATA3 as the first transcriptional factor to positively regulate TbetaRIII expression in human cells. We localize GATA3's binding to a 10-bp region of the TbetaRIII proximal promoter. We demonstrate that GATA3 mRNA is downregulated in all stages, of ccRCC, mechanistically show that GATA3 is methylated in ccRCC patient tumor tissues as well as cell lines, and that inhibiting GATA3 expression in normal renal epithelial cells downregulates TbetaRIII mRNA and protein expression. These data support a sequential model whereby loss of GATA3 expression through epigenetic silencing decreases TbetaRIII expression during ccRCC progression.

Site-directed mutagenesis of the substrate-binding cleft of human estrogen sulfotransferase.

The sulfonation of estrogens by human estrogen sulfotransferase (humSULT1E1) plays a vital role in controlling the active levels of these hormones in the body. To understand more fully the structural and functional characteristics of humSULT1E1, we have carried out site-directed mutagenesis of critical amino acids found in the substrate-binding cleft. Three single amino acid mutations of humSULT1E1 (V145E, H107A, and K85A) were created in this study. Kinetic studies were used to provide information about the importance of these residues in substrate specificity and catalysis, using a variety of substrates. Lysine at position 85 has been proposed to be within hydrogen bonding distance to the 3alpha-phenol group of beta-estradiol, thereby stabilising the substrate in the active site. However, substitution to a neutral alanine at this position improved substrate specificity of humSULT1E1 for beta-estradiol, estrone, and dehydroepiandrosterone (DHEA). The exchange of valine 145 for negatively charged glutamic acid markedly improved the ability of humSULT1E1 to sulfonate dopamine, but caused a reduction in specificity constants toward steroids tested, in particular DHEA. The presence of a histidine residue at position 107 was shown to be essential for the production of a functional protein, as substitution of this amino acid to alanine resulted in complete loss of activity of humSULT1E1 towards all substrates tested.

Anti-ischemic effects of slow-release formulations of nifedipine, isosorbide-5-mononitrate and their combination in patients with coronary heart disease.

Eighteen patients (2 females, 16 males) with coronary artery disease and a positive bicycle exercise test were treated with 50 mg slow-release isosorbide-5-mononitrate (ISMN SR) once daily, 20 mg nifedipine SR twice daily and a combination of both drugs during 2 weeks in a randomized double-blind sequence. Fifteen patients completed the study. The efficacy of each therapy was assessed by ECG stress testing after each treatment period. Both substances were equally effective in the reduction of ischemic ST depression: 0.40 +/- 0.22 mV with placebo, 0.31 +/- 0.16 mV during nifedipine SR and 0.31 +/- 0.29 mV during ISMN SR, 0.28 +/- 0.21 mV during the combination. However, during monotherapy with either nifedipine SR or ISMN SR 6 patients did not improve. The alternative monotherapy was effective in 3 out of 6 patients. Combination treatment gave further advantage only to one third of the patients. We conclude that both nifedipine and ISMN in slow-release formulations are equally effective in the treatment of myocardial ischemia. In the individual patient, however, therapy failure may occur. These patients should be switched to another monotherapy. If both monotherapies are ineffective, combination treatment should be considered.