Effects Of Pleiotrophin（PTN）on The Resistance To Paclitaxel In Ovarian Cancer Cells

Ovarian cancer is one of the most common malignancies in the female reproductive system.Its incidence rate is second only to cervical and endometrial cancer,but with the highest mortality rate.In recent years,the incidence of ovarian cancer is increasing every year,and the incidence age is gradually getting younger.Paclitaxel is the first-line drug for the treatment of ovarian cancer.Most ovarian cancer patients receiving paclitaxel chemotherapy for the first time have good efficacy,but with the increasing frequency of paclitaxel chemotherapy,paclitaxel resistance often occurs in the later stage of treatment,resulting in the death of patients.Drug resistance is an important factor in the high mortality rate of ovarian cancer.The PTN（Pleiotrophin）gene is a proto-oncogene whose expression product is a highly conserved protein composed of 136 amino acids.PTN has been found to have many biological functions,such as promoting angiogenesis,cell proliferation and migration,mitosis,bone development,nervous system development,and anti-apoptosis.PTN is highly expressed during embryonic and neonatal development,and is only expressed in the ovary,testis and brain in adulthood.PTN is also highly expressed in various tumors,including ovarian,rectal,pancreatic,lung,and breast cancer,indicating that PTN may have an important relationship with the occurrence and development of tumors.Studies suggest that the pathogenesis of ovarian cancer may be related to PTN and its receptor.Other studies have shown that PTN is closely related to drug resistance in other tumors.Therefore,To study the relationship between PTN and paclitaxel resistance of ovarian cancer,have great significance for basic research and clinical treatment of ovarian cancer.In this experiment,BALB/C mice were immunized with PTN protein prepared by our laboratory to prepare PTN mab,which was used in other experiments in this paper.Gradient concentration of PTN protein was added into A2780 and SKOV-3cells,then the cells were counted 48 hours later and the growth curve was drawn.It was found that PTN could promote the growth of A2780 and SKOV-3 cells（P < 0.05）.When PTN was added to A2780 and SKOV-3 cells treated with taxol at gradient concentration,MTT results showed that inhibition rate of paclitaxel on A2780 and SKOV-3 cells decreased significantly after the addition of PTN（P < 0.01）.That is,PTN can reduce the sensitivity of A2780 and SKOV-3 cells to paclitaxel.The apoptosis of A2780 and SKOV-3 cells treated with paclitaxel was observed by adding different concentrations of PTN.The results showed that PTN could reduce the total apoptosis rate in a concentration dependent manner（P < 0.05;P < 0.01）.A2780 and SKOV-3 cells were transfected with sh-PTN-1,sh-PTN-2 and sh-NC plasmids.PCR and Western blot showed that they had good interference efficiency（P < 0.05;P <0.01）.To further explore the effect of PTN on paclitaxel resistance of ovarian cancer cells,the same concentration gradient of paclitaxel was added to A2780 and SKOV-3cells transfected with sh-PTN-1 and sh-NC plasmids.MTT results showed that,compared with the Control group,the inhibition rate of A2780 and SKOV-3 cells transfected with sh-PTN-1 was increased（P < 0.05）,and A2780 and SKOV-3 cells were more sensitive to paclitaxel after silenced PTN expression.Further apoptosis assay showed that paclitaxel-induced total apoptosis rates of A2780 and SKOV-3 cells transfected with sh-PTN-1 plasmid was significantly increased compared with Control group（P< 0.05;P< 0.01）.These results suggest that PTN has a certain anti-apoptotic effect.Paclitaxel was added to A2780 and SKOV-3 cells transfected with sh-PTN-1plasmid,and the expression levels of Cleaved PARP were detected by Western blot.The results showed that the expression of Cleaved PARP was higher in the group of cells transfected with sh-PTN-1（P< 0.05;P< 0.01）,indicating that PTN had some anti-apoptotic effect and PTN could enhance the resistance of ovarian cancer cells to paclitaxel.PTN can promote the proliferation of A2780 and SKOV-3 ovarian cancer cells,reduce the inhibitory of paclitaxel on ovarian cancer cells,and reduce the apoptosis of ovarian cancer cells induced by paclitaxel.PTN can improve the resistance of ovarian cancer cells to paclitaxel.