TPA Attenuates Doxorubicin-induced Cardiac Injury And Increase Tumor Suppression

Doxorubicin(DOX)is a broad-spectrum antitumor antibiotic that has been widely used for treatment of several cancers,including breast,ovarian,and prostate cancers.However,clinical efficacy is complicated by drug resistant and a doserelated cardiotoxicity,so that the dose used is strictly limited.Clinical recommendations DOX cumulative dose should not exceed 400mg/m~2.Even at these restricted doses,cardiac toxicity occurs.The relative risk of cardiac death is significantly greater than the normal population even up to 25 years after therapy with DOX for childhood malignancy.The cardiac injury induced by DOX takes many forms but the most clinically relevant is the development of dilated cardiomyopathy.Therefore,looking for drugs that can overcome the cardiac toxicity and increase the chemotherapeutic efficacy of DOX have a very broad clinical application prospect.TPA have been reported to modulate diverse cellular responses such as gene transcription,cellular growth and differentiation,programmed cell death,through protein kinase C(PKC).TPA also have been reported to regulate the activity of Na+-K+-ATP and increase the expression of Hsp70 in the model of myocardial ischemic-reperfusion injury.TPA also can regulate energy metabolism in mitochondrial respiratory chain,which plays a key role in protecting damaged myocardium.Hence we assessed whether DOX-induced cardiac dysfunction could be prevented by co-administration of TPA and whether administration of TPA increase the chemotherapeutic efficacy of DOX.Methods 1 The effects of TPA combined with DOX on K562 and A549 cell lines 1.1 Cell culture A549 and K562 cell lines were cultured in DMEM high glucose or RM-1640 medium supplemented with 10% Fetal bovine serum,were maintained in a humidified atmosphere of 5% CO2 in air at 37°C and were routinely subcultured every 3 days.1.2 Cell proliferation measurements A549 and K562 cells were exposed to drug alone or combined with TPA for 48 h,and the MTT assay was used to measure the inhibition rate,and then draw time-dependent and concentration-dependent curves.To evaluate the effect of TPA on anti-tumor effect of DOX after the data were statistically analyzed by SPSS17.0.2 Effects of TPA on DOX-induced damage of myocardial H9C2 cells The culture and inhibition rate of H9C2 cells were measured with the previous methods and the LDH activity of cell culture medium was measured by Kit,and then evaluate the effect of TPA on DOX-induced H9C2 cell injury.3 Effects of TPA on DOX induced toxicity in mice 3.1 Effects of TPA on mortality induced by DOX induced acute toxicity in mice DOX was administered intravenously at a cumulative dose of 22 mg/kg at one time.TPA treatment was commenced 3 days after DOX chemotherapy,5 days following completion of the DOX.We observed the effect of TPA on mortality and survival of mice induced by DOX.3.2 Effects of TPA on dose restricted toxicity of DOX Mice were randomly separated into three experimental groups and injected with(i)vehicle,(ii)DOX,(iii)DOX combined with TPA.DOX was administered intravenously at a cumulative dose of 36 mg/kg in nine equal doses every week.TPA was also administered intravenously at a dose of 25 μg/kg 3 times after DOX chemotherapy,3 days following completion of the DOX.We observed the changes of myocardial enzymes and liver function related enzymes at different cumulative doses and compared the differences of pathology of each groups,and then evaluated the effect of TPA on DOX dose-limiting toxicity.4 Effects of TPA on the inhibition rate and toxicity of DOX in tumor-bearing mice S180 cells were implanted into armpit of BALB/c mice,and then treated with DOX and TPA.We observed whether TPA could increase the tumor inhibition rate and decrease the toxicity of DOX.5 Statistical analysis All data were analyzed by SPSS 17.0,and animal survival was analyzed by Graph Pad Prism 5.0.Statistical analysis was performed using ANOVA or independent sample t-test.The test level P is 0.05.Results 1 TPA could increased the antitumor effect of DOX in vitro DOX could inhibited the growth of K562 and A549 cells in a time and concentration dependent manner,and IC50 was 0.88 μmol / L and 3.42 μmol / L.The IC50 of K562 cells to TPA was 4.316 nmol / L,but had little effect on A549 cells.TPA could increased the inhibition of cells induced by DOX.TPA can decreased the IC50 of DOX by 50%.2 TPA have attenuated DOX-induced injury of H9C2 cells TPA could significantly inhibited the proliferation and increased the IC50 of H9C2 to DOX by 2.5 times.In addition to that,TPA attenuated DOX-induced the release of LDH in H9C2 cells(P<0.01).3.1 Effects of TPA on mortality induced by DOX induced acute toxicity in mice TPA could significantly reduce the mortality of mice induced by high dose of DOX and prolong the survival time of mice.The mortality ratio was 100% in model group but 22.2% in TPA treated group.The survival time was 9.64 ± 6.72 days in model group but 16.56 ± 3.97 days in TPA treated group(P<0.01).3.2 Effects of TPA on dose restricted toxicity of DOX In the DOX-induced chronic myocardial injury model,serum myocardial enzyme levels increased along with increased cumulative dose of DOX,and TPA significantly reduced myocardial enzyme increased levels induced by DOX(P<0.01).Cardiomyopathy results showed that TPA treatment group significantly antagonized focal bleeding,nuclear dissolution and myocardial cell necrosis caused by DOX.4 Effects of TPA on the inhibition rate and toxicity of DOX in tumor-bearing mice The results showed that TPA could significantly increase the antitumor effect of DOX,and increase the inhibition rate of DOX from 78.30% to 89.62%(P<0.01).In addition to that,we also found that TPA inhibited the growth of tumor obviously.TPA could improved the myocardial injury induced by DOX.3 Effects of TPA on DOX – induced toxicity in miceConclusions 1 TPA could increased the proliferation tumor cells induced by DOX,and attenuates DOX-induced damage to H9C2 cells.2 TPA could increased increases chemotherapeutic efficacy of doxorubicin and ameliorates cardiac dysfunction.