Bian-Sheng Ji

Alteration in P‐glycoprotein at the blood–brain barrier in the early period of MCAO in rats

The aim of this work was to investigate the alteration in P‐glycoprotein (P‐gp) at the blood–brain barrier (BBB) after middle cerebral artery occlusion (MCAO) in rats.

CJY, an isoflavone, reverses P-glycoprotein-mediated multidrug-resistance in doxorubicin-resistant human myelogenous leukaemia (K562/DOX) cells

In an effort to develop safe and effective multidrug‐resistance (MDR) reversing agents, the effect of CJY, an isoflavone, on the P‐glycoprotein (P‐gp) function and P‐gp‐mediated MDR was evaluated in doxorubicin‐resistant human myelogenous leukaemia (K562/DOX) cells. The results showed that CJY caused a marked increase in accumulation and a notable decrease in efflux of rhodamine 123 (Rh123). The inhibitory effect of the agent on P‐gp function persisted for at least 120 min after removal of 2.5 μM CJY from the incubation medium. The doxorubicin‐induced cytotoxicity, apoptosis and cell cycle perturbations were significantly potentiated by CJY. The intracellular accumulation of doxorubicin was also enhanced. The compound exhibited potent effects in‐vitro on the reversal of P‐gp‐mediated MDR, suggesting that it could become a candidate as an effective MDR reversing agent in cancer chemotherapy.

Modulation of P‐glycoprotein in rat brain microvessel endothelial cells under oxygen glucose deprivation

To investigate modulation of P‐glycoprotein (P‐gp) in rat brain microvessel endothelial cells (rBMECs) under oxygen glucose deprivation (OGD).

N1-(quinolin-2-ylmethyl)butane-1,4-diamine, a polyamine analogue, attenuated injury in in vitro and in vivo models of cerebral ischemia

It has been widely recognized that glutamate (Glu)‐induced cytotoxicity, intracellular calcium overload and excessive free radical production are the key players in the development and progression of ischemic brain injury. Since MK‐801, an antagonist of N‐methyl‐d‐aspartate (NMDA) receptor, showed many adverse reactions that hampered its clinical applications, development of safe and effective agent for the treatment of cerebral ischemia is eagerly required. This study was to investigate the effects of N1‐(quinolin‐2‐ylmethyl)butane‐1,4‐diamine (QMA), a polyamine analogue, on the in vitro and in vivo models of cerebral ischemic damage. The results revealed that pretreatment with QMA could attenuate Glu, putrescine (Put) and oxygen‐glucose deprivation (OGD)‐induced cell death, lipid peroxidation as well as the elevation of reactive oxygen species (ROS) and intracellular [Ca2+]i in pheochromocytoma (PC12) cells and in rat primary cortical neurons. The results also demonstrated that QMA could inhibit NMDA‐mediated intracellular [Ca2+]i accumulation in rat primary cortical neurons and reduce brain infarct volume in middle cerebral artery occlusion (MCAO) rats. The present report suggested that polyamines played a crucial role in the pathological processes of cerebral ischemic damage and that QMA or other novel polyamine analogues could be promising therapeutic candidates for stroke by virtue of their anti‐hypoxia and antioxidation property.

BME, a novel compound of anthraquinone, down regulated P-glycoprotein expression in doxorubicin-resistant human myelogenous leukemia (K562/DOX) cells via generation of reactive oxygen species.

P-glycoprotein (P-gp)-mediated multidrug resistance (MDR) in tumor cells is still a main obstacle for the chemotherapeutic treatment of cancers. Thus, development of effective MDR reversing agents is an important approach in the clinic. The present study revealed that BME, a novel compound of anthraquinone, elevated intracellular accumulation of the P-gp substrates and reduced concentration resulting in 50% inhibition of cell growth (IC50) values for doxorubicin (DOX) in doxorubicin-resistant human myelogenous leukemia (K562/DOX) cells. Further more, BME was also reported to down regulated P-gp expression accompanying with generation of nontoxic low level of intracellular reactive oxygen species (iROS) and activation of extracellular signal-regulated kinase (ERK)1/2 as well as c-JUN N-terminal kinase (JNK). However, treatment with N-acetyl-cysteine (NAC), U0216 and SP600125 almost abolished actions of the BME mentioned above. These results indicated that the effect of the BME on the P-gp may be involved in generation of nontoxic low level of iROS and activation of ERK1/2 or JNK, which suggested valuable clues to screen and develop P-gp reversing agents.

Anti‐tumour effects of HL‐37, a novel anthracene derivative, in‐vivo and in‐vitro

Many anthracene derivatives possess excellent anti‐tumour activity and are extensively used clinically as anti‐tumour agents. However, their clinical use is frequently limited by emergence of multidrug resistance (MDR) in tumour cells. Therefore, new agents with the ability to overcome MDR are needed for cancer treatment. HL‐37, a novel anthracene derivative, exhibited potent anti‐cancer activity in both drug‐sensitive (K562) and multidrug‐resistant (K562/DOX) leukaemia cells. Mechanistically, we found that HL‐37 was neither a substrate nor an inhibitor of P‐glycoprotein (P‐gp) and could overcome apoptotic resistance via up‐regulation of p53 protein and down‐regulation of Bcl‐xL protein. In addition, HL‐37 also induced K562/DOX cell apoptosis and a decrease in G0/G1 phase. Moreover, reduction of mitochondrial membrane potential, release of cytochrome c and an increased expression of cleaved protein fragment of caspase‐3, caspase‐9 and caspase‐8 were also observed. Importantly, HL‐37 was found to be better tolerated and more effective at inhibiting tumour growth than bisantrene in a xenograft mouse model.

In vitro and in vivo study of dolichyl phosphate on the efflux activity of P-glycoprotein at the blood–brain barrier

It has been commonly recognized that accumulated amyloid‐β (Aβ) in the brain plays a crucial role in the pathogenesis of Alzheimers disease (AD). Since the deficiency of the P‐glycoprotein (P‐gp) at the blood–brain barrier (BBB) in AD may aggravate Aβ deposition and the P‐gp reversal agents display lower selectivity of the action, to selectively restore activity of the efflux pump is eagerly required. This study was designed to investigate the influence of dolichyl‐phosphate (dolichyl‐P) on the P‐gp at the BBB. The results revealed that treatment with dolichyl‐P increased transendothelial transfer of Rhodamine123 (Rh123) and Aβ42 from the apical compartment to the basolateral compartment but reduced that from the basolateral compartment to the apical compartment in the co‐culture of rat brain microvessel endothelial cells (rBMECs) and astrocytes, down regulated P‐gp expression in rBMECs and significantly elevated content of Rh123 in rat cortex and hippocampus tissues. The present results implied that accumulated dolichyl‐P in the brain may exert an important role in the depression of the P‐gp at the BBB, which may suggest valuable clues to promote function of the pump at the BBB in AD.

CJZ3, a lomerizine derivative, modulates P-glycoprotein function in rat brain microvessel endothelial cells

AbstractAim:To investigate the modulatory effect of CJZ3, a lomerizine derivative, on P-glycoprotein (P-gp) function in rat brain microvessel endothelial cells (RBMEC).Methods:RBMEC were isolated and cultured in Dulbeccos modified Eagles medium/F12 (1:1)medium, and the amount of intracellular rhodamine 123 (Rh123) was determined using a fluorescence spectrophotometer to evaluate the modulatory effect of CJZ3 on P-gp function.Results:The accumulation of Rh123 was potentiated in a concentration-dependent manner after incubation with CJZ3 for RBMEC, but not for human umbilical vein endothelial cells (HUVEC). CJZ3 caused the accumulation of intracellular Rh123 in a time-dependent manner and significantly decreased the efflux of Rh123 from the cells. The inhibitory effect of CJZ3 on P-gp function was reversible and remained for 120 min after CJZ3 (2.5 umol/L) was removed from the medium.Conclusion:CJZ3 has a potent in vitro effect on the inhibition of P-gp function.

3-butyl-6-fluoro-1(3H)-isobenzofuranone (6-F-NBP), a derivative of dl-n-butylphthalide, inhibits glutamate-induced cytotoxicity in PC12 cells

It is widely recognized that glutamate (Glu)‐induced cytotoxicity, intracellular calcium overload and the excessive free radical production are key events in the development and progression of ischemic brain injury. dl‐3‐n‐butylphthalide (NBP), an anti‐ischemic agent, has therapeutic effects in animal models of vascular dementia. The aim of the present study was to investigate the protective effect of 3‐butyl‐6‐fluoro‐1(3H)‐isobenzofuranone (6‐F‐NBP), a derivative of NBP on Glu‐induced cytotoxicity in rat pheochromocytoma (PC12) cells, and to compare this action with NBP. The results showed that after 24‐h incubation with Glu (5 mM), cell viability and mitochondrial membrane potential (MMP) were decreased. In contrast, the content of reactive oxygen species (ROS), activity of nitric oxide synthase (NOS), and apoptosis rate, as well as intracellular accumulation of [Ca2+]i, were increased, 6‐F‐NBP inhibited the damage induced by Glu in a dose‐dependent manner and exerted a more potent effect than NBP, indicating that 6‐F‐NBP exhibited a protective effect against Glu‐induced cytotoxicity in cultured PC12 cells. Drug Dev Res 73: 11–17, 2012.

3-butyl-6-fluoro-1 (3H)-isobenzofuranone, a derivative of dl-n-butylphthalide, attenuates hydrogen peroxide-induced damage in PC12 cells

The anti‐cerebral ischemia agent, dl‐3‐n‐butylphthalide (NBP), is effective in models of vascular dementia in animals. The present study investigates the protective effect of 3‐butyl‐6‐fluoro‐1 (3H)‐isobenzofuranone (6‐F‐NBP), a fluoro derivative of dl‐nbutylphthalide, in hydrogen peroxide (H2O2)‐induced damage in PC12 cells. Exposure of PC12 cells to H2O2 for 24 h led to decreased cell survival, glutathione peroxidase (GSH‐PX), and mitochondrial membrane potential (MMP). In contrast, malondialdehyde (MDA) production, nitric oxide synthase (NOS) activity, nitric oxide (NO) formation, and intracellular reactive oxygen species (ROS) were increased, as was intracellular accumulation of [Ca2+]i. However, pretreatment with 6‐F‐NBP markedly reversed the changes induced by H2O2, exhibiting a protective effect against H2O2‐induced cytotoxicity in PC12 cells. The compound may have therapeutic potential in the treatment of cerebral ischemia by inhibiting the oxidative damage. Drug Dev Res 72: 259–264, 2011.