Multidrug efflux transporter P-glycoprotein (P-gp) is highly expressed on membrane of tumor cells and supposed to be implicated in the resistance to tumor chemotherapy. However, currently none of P-gp inhibitors has been approved by Food and Drug Administration not only due to toxicity but also lack of efficacy in clinical trials.
To solve the problem, our lab synthesized a novel compound named 1416 [1-(2,6-dimethylphenoxy)-3,4-dimethoxyphenylethylamino) propane hydrochloride] with the hope of high P-gp inhibition and low side effects. Caco-2 cell monolayer and tumor bearing mice were used to evaluate the P-gp inhibition of 1416 in vitro and in vivo, respectively. One of its potential side effects, calcium antagonism was also evaluated.
Results showed that 1416 showed a similar P-gp inhibition as verapamil in Caco-2 cell monolayer. No significant difference was observed in antitumor enhancement when the optical isomers of 1416 (D-1416 and L-1416) were co-administered with vinblastine. In calcium antagonism, L-1416 showed less calcium inhibition than both D-1416 and verapamil.
The novel compound 1416 could significantly increase the antitumor effects of cytotoxic drugs and one of its optical isomers, L-1416, might be more promising due to its potential low calcium antagonism.
2012-12-01·Bioscience Reports4区 · 生物学
Overcoming multidrug-resistance in vitro and in vivo using the novel P-glycoprotein inhibitor 1416
MDR (multidrug-resistance) represents a major obstacle to successful cancer chemotherapy and is usually accomplished by overexpression of P-gp (P-glycoprotein). Much effort has been devoted to developing P-gp inhibitors to modulate MDR. However, none of the inhibitors on the market have been successful. 1416 [1-(2,6-dimethylphenoxy)-2-(3,4-dimethoxyphenylethylamino)propane hydrochloride (phenoprolamine hydrochloride)] is a new VER (verapamil) analogue with a higher IC50 for blocking calcium channel currents than VER. In the present paper, we examined the inhibition effect of 1416 on P-gp both in vitro and in vivo. 1416 significantly enhanced cytotoxicity of VBL (vinblastine) in P-gp-overexpressed human multidrug-resistant K562/ADM (adriamycin) and KBV cells, but had no such effect on the parent K562 and KB cells. The MDR-modulating function of 1416 was further confirmed by increasing intracellular Rh123 (rhodanmine123) content in MDR cells. Human K562/ADM xenograft-nude mice model verified that 1416 potentiates the antitumour activity of VBL in vivo. RT-PCR (reverse transcriptase-PCR) and FACS analysis demonstrated that the expression of MDR1/P-gp was not affected by 1416 treatment. All these observations suggest that 1416 could be a promising agent for overcoming MDR in cancer chemotherapy.
2006-01-01·Current Topics in Medicinal Chemistry (Sharjah, United Arab Emirates)4区 · 医学
Glycine/NMDA receptor antagonists as potential CNS therapeutic agents: ACEA-1021 and related compounds
4区 · 医学
作者: Cai, Sui Xiong
Glutamate is the main excitatory neurotransmitter in central nervous system (CNS) and NMDA receptors are one of the major classes of ionotropic glutamate receptors. NMDA receptors have been known to play critical roles in normal CNS activities, as well as in many pathological conditions, including both acute and chronic diseases. The discovery of glycine as a coagonist of NMDA receptors has led to intensive research of glycine/NMDA antagonists as potential CNS drugs. The robust efficacy of glycine/NMDA antagonists, such as ACEA-1021 (5), in animal model of brain ischemia, together with good safety profile in animal models and in clinical trials, suggested that this class of NMDA antagonists should have good chance of success in the clinic as neuroprotectants. The clinical trial of ACEA-1021 for stroke was discontinued, mainly due to low solubility and lack of metabolism of the drug that led to the observation of crystals in the urine of some of the patients. However, through SAR studies, compounds such as ACEA-1416 (10) have been identified with improved properties, such as higher in vivo potency and site for potential metabolism. Therefore these compounds should be able to overcome some of the liabilities of ACEA-1021 and potentially could be developed as neuroprotectants. Based on the preclinical and clinical studies of glycine/NMDA antagonists, as well as the clinical experiences with t-PA, initiation of treatment within a short time window after the onset of stroke could be critical for the success of these antagonists in clinical trials. This can be accomplished by implementing the procedure developed for t-PA clinical trials, with modification based on the safety profile of glycine/NMDA antagonists, for future clinical trial to administer the drug as soon as possible after stroke onset. In addition, glycine/NMDA antagonists also have other potential therapeutic applications, such as for the treatment of traumatic brain injury, pain, cocaine overdose and convulsions.