Preliminary Study On The Inhibitory Effect Of PD-0332991 On The Proliferation Of Gastric Cancer Cells

Background:Gastric cancer(GC),a digestive disease,is one of the most aggressive cancer,and has been ranked as the third leading cause of cancer-related deaths worldwide.China is a country with high incidence of morbidity and death of the GC accounting for about 50%of the world.The disease burden is serious and is the key of cancer prevention and treatment.According to the cancer statistics of 2015,the GC incidence ranked as the second in male and the third for female among the top five cancers in China.The ratio male to female was 2:1.Although the incidence and mortality of GC are lower than before,the number of deaths remains high,due to the growth of the population base and the aging population.What is more,it is easy to be neglected,due to the lack of specific symptoms in early stage.Despite the many therapeutic approaches such as chemotherapy,radiotherapy,or combinations,the overall 5-year survival rate is only 20%.Thence,it is so urgent to find a novel drug for treating GC with strong specificity,remarkable curative effect and less side effectsPD-0332991 is an orally available,highly specific and reversible inhibitor for CDK4/6 kinase activity.There are some new research findings demonstrated that PD-0332991 can exert an anti-proliferative effect in endometrial cancer,malignant pleural mesothelioma cells,hepatocellular carcinoma and other tumors.More importantly,the US Food and Drug Administration(FDA)accelerated the approval of PD0332991(IBRANCE(?),palbociclib)in combination with letrozole as first-line therapeutic approach in estrogen receptor positive(ER+)and human epidermal growth factor receptor 2 negative(HER-2-)postmenopausal metastatic breast cancer in 2015,or in combination with fulvestrant for the therapeutic option of hormone receptor-positive(HR+)and HER-2-advanced or metastatic breast cancer.Whether PD-0332991 could be applied to treat GC remains currently unclearObjective:In this study,we will identify the antitumor effect of PD-0332991 against five GC cell lines and elucidate its preliminary related mechanismMethods:The drug sensitivity of PD-0332991 on cell proliferation were determined in 5 GC cell lines(MGC-803,HGC-27,BGC-823,SGC-7901 and AGS)by MTS.The blood gas analyzer was used to detect the effects of PD-0332991 on glucose metabolism related indicators,such as glucose(Glu),lactic acid(Lac)and base excess(BE).The PD-0332991 on the secretion of related tumor carbohydrate antigens,such as CA12-5,CA19-9,CA72-4,HE4,CEA and pro-GRP was assessed by automatic biochemical immunoassay.Annexin V-FITC/PI double staining by flow cytometry was to examine the effects of PD-0332991 on apoptosis of GC cells.Anti-PD-L1/PI double staining by flow cytometry was used to evaluate the impact of PD-0332991 on the expression of programmed cell death ligand 1(PD-L1)in GC cells.Results:MTS assay revealed that PD-0332991 inhibited the proliferation of all five GC cell lines in a dose-dependent way,with IC50 values ranging from 0.27 to 10 ?M,after 48 h of incubation.GC cells treated with PD-0332991 displayed no statistical difference in glucose metabolism related indicators(Glu consumption,Lac production and the amount of change in BE),compared with that of the vehicle group.The automatic biochemical immunoassay revealed that PD-0332991 had different impact on secretions of related tumor carbohydrate antigens(CA12-5,CA19-9,CA72-4,HE4,CEA and pro-GRP)in five GC cells.For MGC-803 and HGC-27,PD-0332991 had no significant effect.As for BGC-823,PD-0332991 attenuated the secretion of CA72-4 and pro-GRP in a concentration-dependent manner.For SGC-7901 and AGS,PD-0332991 obviously reduced the CA12-5 secretion and showed little correlation with concentration.Annexin V-FITC/PI double staining in combination with flow cytometry indicated that PD-0332991 induced apoptosis in MGC-803,and had little correlation with concentration.For HGC-27,PD-0332991 induced apoptosis in a dose-dependent manner PD-0332991 did not induce apoptosis for BGC-823.It also gave rise to apoptosis in SGC-7901.PD-0332991 suggested no obvious effect on AGS apoptosis.Anti-PD-L1/PI double staining by flow cytometry showed that,PD-0332991 had no effect on PD-L1 expression and was not associated with concentration for HGC-27.For MGC-803,PD-0332991 augmented the expression level of PD-L1 and was not associated with concentration.For SGC-7901,PD-0332991 significantly increased PD-L1 expression in a time-dependent manner.For AGS,PD-0332991 had no significant effect on PD-L1 expression and was not associated with timeConclusionsCollectively,this research identified PD-0332991,a promising inhibitor of CDK4/6,that significantly suppress GC cells growth.However,it had no obvious effect on glucose metabolism;in terms of the secretion amount of tumor carbohydrate-related antigens,it could have various effects on different cells,as well as cell apoptosis.In addition,PD-0332991 could also intensify the expression of PD-L1 in GC cell membrane.Therefore,PD-0332991 may be a potential drug for the treatment of GC,that warrants further clinical investigation.