ABSTRACT
[ ABSTRACT] AIM:To investigate the mechanism of L-type calcium channel ( L-Ca2+)/calpain signal transduc-tion pathway in verapamil inversing resistance of papillary thyroid carcinoma to doxorubicin .METHODS:Human papillary thyroid carcinoma TPC-1 cells were cultured for 2 d.For determining the appropriate concentrations and treatment time of verapamil and doxorubicin , a compatibility test was conducted to detect the cell viability by CCK-8 assay.The cells were divided into control group , doxorubicin group , verapamil group and doxorubicin +verapamil group .The techniques of whole-cell patch-clamp was used to record L-Ca2+currents.The protein expression levels of calpain 1 and LC3 were detec-ted by Western blot .RESULTS: Compared with control group , the density of L-Ca2+current decreased in doxorubicin group and verapamil group (P<0.05).Compared with verapamil group , the density of L-Ca2+current decreased in doxo-rubicin+verapamil group (P<0.01).Compared with control group, the expression of calpain 1 decreased in doxorubicin group and verapamil group (P<0.05).Compared with doxorubicin group , the expression of calpain 1 decreased in doxo-rubicin+verapamil group (P<0.05).Compared with control group , the expression of LC3 increased in doxorubicin group and verapamil group (P<0.05).Compared with doxorubicin group , the expression of LC3 increased in doxorubicin +ver-apamil group ( P<0.01) .CONCLUSION:The drug resistance of TPC-1 cells to doxorubicin may be related to the in-crease in autophagic activity .Verapamil further increases autophagic activity of TPC-1 cells, resulting in autophagic death and inversing the resistance of TPC-1 cells to doxorubicin .The mechanism may be involved in L-Ca2+/calpain 1 signal transduction pathway of autophagy .
ABSTRACT
AIM: To investigate the anti-apoptotic effect of nerve growth factor (NGF) on PC12 cells and to observe the mechanism of signal transduction of JNK pathway. METHODS: PC12 cells were treated with 6-hydroxydopamine (6-OHDA) to induce cell apoptosis. NGF and SP600125, the c-Jun N-terminal kinase inhibitors, were added respectively in order to study the relationship between the activity of c-Jun N-terminal kinase and apoptosis of PC12 cells. The cells were divided into control group, 6- OHDA group, NGF group, 6-OHDA plus NGF group, NGF plus SP600125 group. The apoptotic rates of PC12 cells with different treatments were detected by flow cytometry and activities of JNK in PC12 cells were determined by Western blotting. RESULTS: 6-OHDA increased the apoptotic rate and activity of JNK1 in PC12 cells. Incubation with SP600125 or NGF for 15 min before adding 6-OHDA decreased the apoptotic rate of PC12 cells and activity of JNK1 in PC12 cells.CONCLUSION: Activity of JNK is involved in the pro-apoptotic effect of 6-OHDA on PC12 cells. Anti-apoptotic effect of NGF on PC12 cells affected by 6-OHDA is related to the decrease in the activity of JNK1.