h-89 and tetrandrine

Tetrandrine, a bisbenzylisoquinoline alkaloid that was isolated from the medicinal plant Stephania tetrandrine S. Moore, was recently identified as a novel chemotherapy drug. Tetrandrine exhibited a potential antitumor effect on multiple types of cancer. Notably, an enhanced therapeutic efficacy was identified when tetrandrine was combined with a molecularly targeted agent. H89 is a potent inhibitor of protein kinase A and is an isoquinoline sulfonamide.. The effects of H89 combined with tetrandrine were investigated in vitro with respect to cell viability, apoptosis and autophagy, and synergy was assessed by calculation of the combination index. The mechanism was examined by western blot, flow cytometry and fluorescence microscopy. This combination was also evaluated in a mouse xenograft model; tumor growth and tumor lysates were analyzed, and a TUNEL assay was performed.. Combined treatment with H89 and tetrandrine exerts a mostly synergistic anti-tumor effect on human cancer cells in vitro and in vivo while sparing normal cells. Mechanistically, the combined therapy significantly induced cancer cell apoptosis and autophagy, which were mediated by ROS regulated PKA and ERK signaling. Moreover, Mcl-1 and c-Myc were shown to play a critical role in H89/tetrandrine combined treatment. Mcl-1 ectopic expression significantly diminished H89/tetrandrine sensitivity and amplified c-Myc sensitized cancer cells in the combined treatment.. Our findings demonstrate that the combination of tetrandrine and H89 exhibits an enhanced therapeutic effect and may become a promising therapeutic strategy for cancer patients. They also indicate a significant clinical application of tetrandrine in the treatment of human cancer. Moreover, the combination of H89/tetrandrine provides new selectively targeted therapeutic strategies for patients with c-Myc amplification.

Topics: Animals; Antineoplastic Agents; Apoptosis; Autophagy; Benzylisoquinolines; Cell Line, Tumor; Cell Survival; Cyclic AMP-Dependent Protein Kinases; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Resistance, Neoplasm; Drug Synergism; Genes, myc; Genes, Reporter; Humans; Isoquinolines; Mice; Myeloid Cell Leukemia Sequence 1 Protein; Protein Kinase Inhibitors; Reactive Oxygen Species; Sulfonamides; Xenograft Model Antitumor Assays

To evaluate the effects of hyperprolactinemia on aldosterone secretion and its mechanisms of action in ovariectomized (OVX) rats.. Hyperprolactinemia was induced by the transplantation of rat anterior pituitary (AP) glands under the kidney capsule for 6 weeks in female rats. Control rats underwent cerebral cortex (CX) transplantation. Four weeks after transplantation, the rats were OVX 2 weeks before decapitation. After decapitation, the trunk blood was collected, and the adrenal glands of CX- and AP-grafted rats were prepared as zona glomerulosa (ZG) cells for in vitro study.. Plasma prolactin and aldosterone in the rats were increased by AP gland transplantation. In the in vitro study, the basal aldosterone secretion by the adrenal ZG cells was higher in AP-grafted rats than in CX-grafted rats. The AP-grafted group showed increased responsiveness to angiotensin II (10(-8) M), KCl (8 x 10(-3) M), or 8-bromo-adenosine 3',5'-cyclic monophosphate (8-br-cAMP; 10(-4) M, a membrane-permeable analogue of cAMP) with regard to aldosterone secretion as compared with the CX-grafted group. N-(2-[p-Bromocinnamylamine]ethyl)-5-isoquinolinesulfonamide (H89; 10(-6), 10(-5) M, a protein kinase A inhibitor) or tetrandrine (10(-5) M, a blocker for both L-type and T-type Ca2+ channels) induced a greater suppression of aldosterone secretion in the AP-grafted group than in the CX-grafted group. No significant differences between the CX- and AP-grafted groups were observed, however, with regard to the adrenocorticotropichormone (10(-9) M)-, forskolin (10(-5) M, an adenylyl cyclase activator)-, or nifedipine (10(-5) M, an L-type Ca2+ channel blocker)-induced responsiveness of aldosterone secretion. In addition, there was no difference in the expression of desmolase (i.e., cytochrome P450 side-chain cleavage enzyme) in ZG cells between AP- and CX-grafted rats. The conversions of 25-OH-cholesterol into pregnenolone in the presence of trilostane (an inhibitor of 3beta-hydroxysteroid dehydrogenase) and corticosterone into aldosterone, as well as the expression of the steroidogenic acute regulatory protein in ZG cells, were greater in AP-grafted rats than in CX-grafted rats.. These results suggest that hyperprolactinemia increases basal, angiotensin II- and KCl-stimulated aldosterone secretion by ZG cells in OVX rats through activation of T-type Ca2+ channels, the post-cAMP and protein kinase A pathway, cytochrome P450 side-chain cleavage enzyme, and aldosterone synthase, as well as by causing increased expression of steroidogenic acute regulatory protein in ZG cells.

Topics: 8-Bromo Cyclic Adenosine Monophosphate; Adenylyl Cyclases; Aldosterone; Alkaloids; Angiotensin II; Animals; Benzylisoquinolines; Calcium Channels, T-Type; Cells, Cultured; Cholesterol Side-Chain Cleavage Enzyme; Cyclic AMP-Dependent Protein Kinases; Cytochrome P-450 CYP11B2; Female; Hyperprolactinemia; Isoquinolines; Ovariectomy; Phosphoproteins; Pituitary Gland, Anterior; Potassium Chloride; Prolactin; Rats; Rats, Sprague-Dawley; Sulfonamides; Zona Glomerulosa