Comparing the frequency of CD33+ pSTAT3+ myeloid-derived suppressor cells and IL-17+ lymphocytes in patients with prostate cancer and benign prostatic hyperplasia

Prostate cancer (PCa) is one of the most epidemic types of cancer in men. The tumor microenvironment (TME) of PCa is involved in the emergence of immunosuppressive factors such as myeloid-derived suppressor cells (MDSC), which regulate the immune system by several mechanisms, including interleukin (IL)-10 production. On the other hand, IL-17⁺ helper T cells (Th17) induce MDSCs and chronic inflammation in TME by producing IL-17. This study demonstrated that the frequency of CD33⁺ pSTAT3⁺ MDSC and IL-17⁺ lymphocyte as well as IL-10 messenger RNA (mRNA) expression were significantly higher in the PCa patients than in the benign prostatic hyperplasia (BPH) group. Moreover, there was no significant relationship between the frequency of CD33⁺ pSTAT3⁺ MDSC, and IL-17⁺ lymphocyte with Gleason scores in the PCa group. We suggested that the higher frequency of CD33⁺ pSTAT3⁺ MDSC and IL-17⁺ lymphocyte and the more frequent expression of IL-10 mRNA in PCa patients may play roles in tumor progression from BPH to PCa.     

The Mechanism of the Calorigenic Action of Thyroid Hormone : Stimulation of Na+ + K+-activated adenosinetriphosphatase activity

In an earlier study, we proposed that thyroid hormone stimulation of energy utilization by the Na⁺ pump mediates the calorigenic response. In this study, the effects of triiodothyronine (T₃) on total oxygen consumption (Q_OO2), the ouabain-sensitive oxygen consumption [Q_OO2(t)], and NaK-ATPase in liver, kidney, and cerebrum were measured. In liver, ~90% of the increase in Q_OO2 produced by T₃ in either thyroidectomized or euthyroid rats was attributable to the increase in Q_OO2(t). In kidney, the increase in Q_OO2(t) accounted for 29% of the increase in Q_OO2 in thyroidectomized and 46% of the increase in Q_OO2 in euthyroid rats. There was no demonstrable effect of T₃ in euthyroid rats on Q_OO2 or Q_OO2(t) of cerebral slices. The effects of T₃ on NaK-ATPase activity in homogenates were as follows: In liver +81% from euthyroid rats and +54% from hypothyroid rats. In kidney, +21% from euthyroid rats and +69% from hypothyroid rats. T₃ in euthyroid rats produced no significant changes in NaK-ATPase or Mg-ATPase activity of cerebral homogenates. Liver plasma membrane fractions showed a 69% increase in NaK-ATPase and no significant changes in either Mg-ATPase or 5'-nucleotidase activities after T₃ injection. These results indicate that thyroid hormones stimulate NaK-ATPase activity differentially. This effect may account, at least in part, for the calorigenic effects of these hormones.     

Design of an Insulin Analog with Enhanced Receptor Binding Selectivity: RATIONALE, STRUCTURE, AND THERAPEUTIC IMPLICATIONS*

Insulin binds with high affinity to the insulin receptor (IR) and with low affinity to the type 1 insulin-like growth factor (IGF) receptor (IGFR). Such cross-binding, which reflects homologies within the insulin-IGF signaling system, is of clinical interest in relation to the association between hyperinsulinemia and colorectal cancer. Here, we employ nonstandard mutagenesis to design an insulin analog with enhanced affinity for the IR but reduced affinity for the IGFR. Unnatural amino acids were introduced by chemical synthesis at the N- and C-capping positions of a recognition α-helix (residues A1 and A8). These sites adjoin the hormone-receptor interface as indicated by photocross-linking studies. Specificity is enhanced more than 3-fold on the following: (i) substitution of Gly^A1 by d-Ala or d-Leu, and (ii) substitution of Thr^A8 by diaminobutyric acid (Dab). The crystal structure of [d-Ala^A1,Dab^A8]insulin, as determined within a T₆ zinc hexamer to a resolution of 1.35 Å, is essentially identical to that of human insulin. The nonstandard side chains project into solvent at the edge of a conserved receptor-binding surface shared by insulin and IGF-I. Our results demonstrate that modifications at this edge discriminate between IR and IGFR. Because hyperinsulinemia is typically characterized by a 3-fold increase in integrated postprandial insulin concentrations, we envisage that such insulin analogs may facilitate studies of the initiation and progression of cancer in animal models. Future development of clinical analogs lacking significant IGFR cross-binding may enhance the safety of insulin replacement therapy in patients with type 2 diabetes mellitus at increased risk of colorectal cancer.     

Effect of thyroid hormone on the distribution and activity of Na, K-ATPase in ventricular myocardium

Employing detergent-free sucrose-density gradient fractionation method we isolated cholesterol-rich lighter membrane fractions containing ∼10% of protein, ∼30% of cholesterol in membranes of ventricular myocardium. Cholesterol-rich lighter membrane fractions contain >70% of Na, K-ATPase and caveolins 1 and 3 and <10% of β-actin. Treatment of hypothyroid rats with T₃ increased the relative abundance of both α1 and β1 Na, K-ATPase subunits in total membranes by 4- to 5-fold (with no change in caveolin-3), and resulted in 1.9-fold increase in enzyme activity. T₃-induced Na, K-ATPase subunits were preferentially distributed to the lighter fractions (#s 4, 5 and 6); and increased abundance of α1 and β1 were 34-70% and 43-68%, respectively. We conclude that the activity of Na, K-ATPase is not uniform in cardiac membranes, and while a significant amount of Na, K-ATPase is present in cardiac cholesterol-rich membrane fractions, the intrinsic activity is significantly less than the enzyme present in relatively cholesterol-poor membranes.     

Mutations of peripheral myelin protein 22 result in defective trafficking through mechanisms which may be common to diseases involving tetraspan membrane proteins

Phenotypes of several heritable disorders including forms of hearing loss, myelin diseases, hypomagnesemia, and cataracts are linked to missense mutations in single alleles encoding membrane proteins having four transmembrane spans. In some cases, the mutant proteins exhibit dominant negative or gain-of-function behavior whereby heterozygous coexpression of mutant and wild-type genes leads to more serious pathology than is the case for individuals in which only a single wild-type allele is expressed. An example is found in the relationship of peripheral myelin protein 22 (PMP22) to Charcot-Marie-Tooth disease (CMTD) type 1A. A number of disease-linked PMP22 mutants fail to undergo normal trafficking beyond the endoplasmic reticulum or intermediate compartment to reach the cell surface. Moreover, recent evidence suggests that pathology resulting from this mistrafficking-based loss of function may also be augmented by the ability of some mutants to disrupt normal trafficking of the product of the wild-type PMP22 allele. The basis for this phenomenon appears to be the heterodimerization of trafficking-incompetent mutants with wild-type PMP22, such that both the wild-type protein and the mutant forms are retained early in the secretory pathway. The full cellular and structural biological details of these observations remain to be elucidated. However, the model suggested by the existing data regarding the relationship of PMP22 to CMTD may be useful to explain phenotypes of several other diseases involving other tetraspan membrane proteins and to facilitate predictions regarding previously undetected disease-protein linkages.     

Differential accumulation of Glut1 in the non-DRM domain of the plasma membrane in response to the inhibition of oxidative phosphorylation

Approximately 50% of Glut1 in the plasma membrane of Clone 9 cells is localized to the detergent-resistant membrane (DRM) fraction. Acute exposure (90 min) to 5mM azide stimulated glucose transport by approximately 4.7-fold and increased the abundance of Glut1 in the non-DRM fraction of the plasma membrane by approximately 2.9-fold while the abundance of Glut1 in the DRMs was not changed. In parallel experiments, approximately 17 h exposure to azide further increased the rate of glucose transport over that observed at 90 min by approximately 33% and increased plasma membrane Glut1 content by approximately 3.5-fold over control. The increase in total plasma membrane Glut1 reflected a approximately 4.7-fold increase of Glut1 content in the non-DRM fraction and a approximately 2.6-fold increase in the DRMs. We conclude that acute exposure to azide increases Glut1 content in the non-DRM fractions, while prolonged exposure to azide increases the Glut1 content in both non-DRM and DRM fractions. These changes may play an important role in the stimulation of glucose transport in response to the inhibition of oxidative phosphorylation.