Synergistic, cytotoxic and apoptotic activities of olmesartan with NF-κB inhibitor against HeLa human cell line.

CONTEXT: Over expression of renin-angiotensin system (RAS) and nuclear factor-kappaB (NF-κB) has a major role in many cancers. It has been suggested that some angiotensin receptor blockers (ARBs) could reduce the proliferation of cancer cells. The role of NF-κB pathway has been documented in cell proliferation. OBJECTIVE: In this study, the role of angiotensin II and NF-κB pathway in human cervical cancer cell line (HeLa) proliferation was studied using olmesartan (as a novel Ag II antagonist) and Bay11-7082 (as NF-κB inhibitor). MATERIALS AND METHODS: HeLa cells were treated with different concentrations of olmesartan and Bay11-7082. Cell proliferation was determined after 24, 48, and 72 h by MTT assay. Synergistic activity of olmesartan with Bay11-7082 was analyzed with Compusyn software. Apoptotic cells were determined using PI staining of DNA fragmentation. RESULTS: Cell viability decreased with olmesartan and Bay11-7082 in HeLa cells by 24, 48 and 72 h. Olmesartan had synergistic activity with Bay11-7082 and combinations of olmesartan with Bay11-7082 decreased cell viability as compared with single agent treatments. Olmesartan and Bay11-7082 induced a sub-G1 peak in flow cytometry histogram of treated cells indicating that apoptotic cell death is involved in olmesartan and Bay11-7082-induced toxicity. DISCUSSION AND CONCLUSION: Results imply that olmesartan and Bay11-7082 inhibit the growth of HeLa cells as a concentration- and time-dependent mode and they have synergistic activity. Results show that RAS and NF-κB pathway blockade lead to significant cytotoxicity against tumor cell line. So, ARBs and NF-κB pathway inhibitors could be considered as good anti-cancer agents in cervix carcinoma after further studies.

The constitutively active N111G-AT1 receptor for angiotensin II modifies the morphology and cytoskeletal organization of HEK-293 cells.

The expression of a constitutively active G protein-coupled receptor is expected to trigger diverse cellular changes ranging from normal to adaptive responses. We report that confluent HEK-293 cells stably expressing the constitutively active mutant N111G-AT1 receptor for angiotensin II spontaneously exhibited dramatic morphological changes and cytoskeletal reorganization. Phase-contrast microscopy revealed that these cells formed a dense monolayer, whereas cells expressing the WT-AT1 receptor displayed large intercellular spaces and numerous filopodia. Confocal microscopy revealed an elaborate web of polymerized actin at the apical and basolateral surfaces of cells expressing the N111G-AT1 receptor. Interestingly, these phenotypic changes were prevented by culturing the cells in the presence of the inverse agonist EXP3174. Similar morphologic rearrangements and de novo polymerized actin structures were found in Ang II-stimulated cells expressing the WT-AT1 receptor. We further showed that AT1 receptor-induced cell-cell contact formation did not require an increase in intracellular Ca2+ concentration or the activity of protein kinase C. However, pretreatment with Y-27632 revealed that Rho-kinase activity was required for cell-cell contact formation upon AT1 receptor activation. These observations demonstrate that the expression of the constitutively active mutant N111G-AT1 receptor had a significant impact on the morphology and cytoskeletal organization of HEK-293 cells, possibly via a mechanism involving the activity of Rho-kinase.

Involvement of NMDA in a plasticity phenomenon observed in the adult frog monocular optokinetic nystagmus.

The frog horizontal monocular optokinetic nystagmus (H-OKN) is asymmetrical, the reflex being evoked by a temporal-nasal (T-N) component, but not by a nasal-temporal (N-T) component. Coil recordings showed that, in adult animals, 8 days of monocular deprivation (by unilateral eyelid suture) provoked the appearance of a N-T component, the H-OKN becoming symmetrical, reacting for both directions of stimulation. This delay was shortened to 2 days following two successive unilateral pretectal administrations of NMDA or of LY 285 265, an NMDA agonist, the first 2 days of eyelid suture. The same results were obtained when chronic microinjections of NMDA or LY 285 265 were achieved, the frogs being maintained in total darkness during the week of eyelid suture. These data indicate that the plasticity phenomenon evidenced in the monocular frog H-OKN depends on the activation of the NMDA receptors of one pretectum. This activation was obtained either by a monocular light stimulation of 8 days duration, or by unilateral administration of drugs activating the NMDA glutamatergic pretectal system. In this last case, the light stimulation was no longer necessary.