Ephrin receptor A2 is an epithelial cell receptor for Epstein-Barr virus entry.

Epstein-Barr virus (EBV) is causally associated with nasopharyngeal carcinoma, 10% of gastric carcinoma and various B cell lymphomas 1 . EBV infects both B cells and epithelial cells 2 . Recently, we reported that epidermal growth factor and Neuropilin 1 markedly enhanced EBV entry into nasopharyngeal epithelial cells 3 . However, knowledge of how EBV infects epithelial cells remains incomplete. To understand the mechanisms through which EBV infects epithelial cells, we integrated microarray and RNA interference screen analyses and found that Ephrin receptor A2 (EphA2) is important for EBV entry into the epithelial cells. EphA2 short interfering RNA knockdown or CRISPR-Cas9 knockout markedly reduced EBV epithelial cell infection, which was mostly restored by EphA2 complementary DNA rescue. EphA2 overexpression increased epithelial cell EBV infection. Soluble EphA2 protein, antibodies against EphA2, soluble EphA2 ligand EphrinA1, or the EphA2 inhibitor 2,5-dimethylpyrrolyl benzoic acid efficiently blocked EBV epithelial cell infection. Mechanistically, EphA2 interacted with EBV entry proteins gH/gL and gB to facilitate EBV internalization and fusion. The EphA2 Ephrin-binding domain and fibronectin type III repeats domain were essential for EphA2-mediated EBV infection, while the intracellular domain was dispensable. This is distinct from Kaposi's sarcoma-associated herpesvirus infection through EphA2 4 . Taken together, our results identify EphA2 as a critical player for EBV epithelial cell entry.

GPR55 promotes migration and adhesion of colon cancer cells indicating a role in metastasis.

BACKGROUND AND PURPOSE: Tumour cell migration and adhesion constitute essential features of metastasis. G-protein coupled receptor 55 (GPR55), a lysophospholipid receptor, has been shown to play an important role in carcinogenesis. Here, we investigated the involvement of GPR55 in migration and metastasis of colon cancer cells. EXPERIMENTAL APPROACH: Adhesion and migration assays using the highly metastatic colon cancer cell line HCT116 and an in vivo assay of liver metastasis were performed. The GPR55 antagonist CID16020046, cannabidiol, a putative GPR55 antagonist and GPR55 siRNA were used to block GPR55 activity in HCT116 colon cancer cells. KEY RESULTS: HCT116 cells showed a significant decrease in adhesion to endothelial cells and in migration after blockade with CID16020046 or cannabidiol. The inhibitory effects of CID16020046 or cannabidiol were averted by GPR55 siRNA knock down in cancer cells. The integrity of endothelial cell monolayers was increased after pretreatment of HCT116 cells with the antagonists or after GPR55 siRNA knockdown while pretreatment with lysophosphatidylinositol (LPI), the endogenous ligand of GPR55, decreased integrity of the monolayers. LPI also induced migration in GPR55 overexpressing HCT116 cells that was blocked by GPR55 antagonists. In a mouse model of metastasis, the arrest of HCT116 cancer cells in the liver was reduced after treatment with CID16020046 or cannabidiol. Increased levels of LPI (18:0) were found in colon cancer patients when compared with healthy individuals. CONCLUSIONS AND IMPLICATIONS: GPR55 is involved in the migratory behaviour of colon carcinoma cells and may serve as a pharmacological target for the prevention of metastasis. © 2015 The British Pharmacological Society.

Lack of weight gain after angiotensin AT1 receptor blockade in diet-induced obesity is partly mediated by an angiotensin-(1-7)/Mas-dependent pathway.

BACKGROUND AND PURPOSE: Angiotensin AT1 receptor antagonists induce weight loss; however, the mechanism underlying this phenomenon is unknown. The Mas receptor agonist angiotensin-(1-7) is a metabolite of angiotensin I and of angiotensin II . As an agonist of Mas receptors, angiotensin-(1-7) has beneficial cardiovascular and metabolic effects. EXPERIMENTAL APPROACH: We investigated the anti-obesity effects of transgenically overexpressed angiotensin-(1-7) in rats. We secondly examined whether weight loss due to telmisartan (8 mg·kg(-1) ·d(-1) ) in diet-induced obese Sprague Dawley (SD) rats can be blocked when the animals were co-treated with the Mas receptor antagonist A779 (24 or 72 µg·kg(-1) ·d(-1) ). KEY RESULTS: In contrast to wild-type controls, transgenic rats overexpressing angiotensin-(1-7) had 1.) diminished body weight when they were regularly fed with chow; 2.) were protected from developing obesity although they were fed with cafeteria diet (CD); 3.) showed a reduced energy intake that was mainly related to a lower CD intake; 5.) remained responsive to leptin despite chronic CD feeding; 6.) had a higher, strain-dependent energy expenditure, and 7.) were protected from developing insulin resistance despite CD feeding. Telmisartan-induced weight loss in SD rats was partially antagonized after a high, but not a low dose of A779. CONCLUSIONS AND IMPLICATIONS: Angiotensin-(1-7) regulated food intake and body weight and contributed to the weight loss after AT1 receptor blockade. Angiotensin-(1-7)-like agonists may be drug candidates for treating obesity.

[The role of thiol antioxidants in restoring mitochondrial functions, modified by microbial metabolites].

The effects of phenolic acids of microbial origin on mitochondrial functions and the possibility of removing their effects by thiol antioxidants dithiotreitol and N-acethylcysteine were studied. The action of some phenolic acids on the redox state of NADH, the membrane potential and calcium capacity of mitochondria is due to their interaction with thiol groups. The partial restoration of mitochondrial functions occurred in the presence of dithiotreitol and N-acethylcysteine, the full recovery (short-term duration) was promoted by the combined action of dithiotreitol and menadione (vitamin K3). It was found that the protective effect of thiol antioxidants became prooxidant one, if the medium contained free iron and compounds with a quinone structure, capable of entering into a redox cycle with thiols. It is shown that the interaction of thiols with iron and menadione is accompanied by absorption of oxygen to form superoxide anion. Prooxidant effect of thiol antioxidants may explain the absence of the protective effect at the later stages of sepsis and systemic inflammatory syndrome.

Retinobenzoic acids. 6. Retinoid antagonists with a heterocyclic ring.

Several candidate retinoid antagonists were designed on the basis of the ligand superfamily concept and synthesized. Retinoidal activities of these benzimidazole and benzodiazepine derivatives were examined by assay of differentiation-inducing activity on human promyelocytic leukemia cell line HL-60. The parent benzimidazole derivative, 4-(5,6,7,8-tetrahydro-5,5,8,8- tetramethylnaphth-[2,3-d]imidazol-2-yl)benzoic acid (7a), and related compounds with a small alkyl group instead of the hydrogen on the nitrogen (1N) atom of the imidazole ring exhibited retinoidal activity, and the potency strongly depended on the bulkiness of the substituent. The compounds having a phenyl or benzyl group on the nitrogen lacked differentiation-inducing activity on HL-60 cells and acted as antagonists to the potent retinoid 4-[(5,6,7,8-tetrahydro-5,5,8,8- tetramethyl-2-naphthalenyl)carbamoyl]benzoic acid (Am80). Among the compounds possessing a seven-membered heterocyclic ring as a linking group, 4-(5H-7,8,9,10-tetrahydro-5,7,7,10,10- pentamethylbenzo[e]- naphtho[2,3-b][1,4]diazepin-13-yl)benzoic acid (16) also exhibited the antagonistic activity. The binding abilities of these compounds to retinoic acid receptors alpha and beta were consistent with their potency for the inhibition of HL-60 cell differentiation induced by the retinoid Am80.

Hypercalcemia induced with an arotinoid in thyroparathyroidectomized rats. New model to study bone resorption in vivo.

A model of stimulated bone resorption was developed using a synthetic retinoid in thyroparathyroidectomized rats. The retinoid induced an increase in bone resorption and in the number of vertebral subperiosteal osteoclasts. The resulting increase in plasma Ca could be used as an easily measured index of bone resorption. Three bisphosphonates produced a dose-related prevention and reversal of retinoid-induced hypercalcemia. Their potencies were similar to those previously obtained by histomorphometry. Irradiation (600 rad) of the rats prevented hypercalcemia but failed to reverse it, showing that proliferation of osteoclast precursor cells was important in inducing, but not in maintaining, bone resorption. Calcitonin produced similar effects on calcemia and prevented the increase in osteoclast number but failed to reverse the increase, suggesting that it inhibited precursor proliferation. This model represents a new tool to study mechanisms of bone resorption and the action of inhibitors in vivo.