Evaluation Of KLK7 Small Molecule Inhibitor In Pancreatic Cancer PDX Model

Objective: To build a subcutaneous xenograft model by transplanting the fresh tumor tissue of pancreatic cancer patient to mouse(PDX model),and explore the inhibitory effect of the KLK7 small molecule inhibitor previously synthesized by our research group on pancreatic cancer PDX model.Methods:(1)Our subject was approved by the Ethics Committee of China Three Gorges University,then one of the patients from the Department of Hepatobiliary and Pancreatic Surgery of the First Clinical Medical College of China Three Gorges University was randomly selected,the imaging examination and pathological test of the patient indicated pancreatic cancer.The operation was completed by the surgeon after consent signed by the patient.A small portion of the tumor specimen was excised and quickly implanted under the skin of mouse to build the pancreatic cancer PDX model,the model was kept by transmitting the tumor from the former generation of mice to the next.(2)After the tumor grew to a diameter of about 10 mm,it was removed from the mouse subcutaneously,use H&E staining to evaluate the pathological feature and Immunohistochemistry staining to confirm the expression of KLK7 in the model.(3)As the tumor formation rate of the PDX model reached plateau,the mice were randomly divided into three groups(control group,10 m M group and 40 m M group),and each group was given a corresponding concentration of the small molecule inhibitor of KLK7 previously synthesized by our research group and the control group was given the same volume of DMSO,the general conditions(mind,diet,sleep,urine,skin,and so on)of the mice during the experiment was observed and record,as well as the tumor formation rate(tumor formation rate = number of tumor formations / number of inoculations × 100%)and changes in tumor volume(V = 1/2 × long diameter × short diameter × short diameter),tumor inhibition rate [tumor inhibition rate =(average tumor weight in the control group-average tumor weight in the experimental group)/ average tumor weight in the control group × 100%].At the end of the experiment,mice were sacrificed,tumors were removed,tumor weight were measured,the tumors and important organs of the mice(heart,liver,spleen,lung,kidney)were stained with H&E to observe the pathological features and whether the important organs of mice were invaded.Results:(1)A PDX model of pancreatic cancer was successfully built,about 14 days after inoculation,the indurations with various sizes could be touched at the subcutaneous inoculation site of mice,and the model was kept successfully.(2)The H&E staining of tumors was in accordance with the typical pathological changes of PDAC,Immunohistochemistry demonstrated that KLK7 protein was highly expressed in the PDX model.(3)The efficacy evaluation was conducted when the PDX model was passaged in vivo to the fourth generation.There was no significant difference in the tendency of body weight changes of the mice between the groups,all of them gradually increased as time goes by,but the weight loss occurred in the high-concentration group at about the fifth week of the experiment;The tumor formation rate of the mice in each group increased as time goes by,and the final tumor formation rate of the 40 m M group was 75%,the 10 m M group was 91.67%,and the control group was 100%,tumor formation rate of the experimental group was lesser than the control group;The tumor volume gradually increases as time goes by,and the tumor volume of the experimental group was significantly smaller than that of the control group,and the difference was statistically significant;The tumor weight in the 40 m M group was(0.124 ± 0.113)g,the 10 m M group was(0.234 ± 0.172)g,and the control group was(0.422 ± 0.163)g,the tumor weight of the experimental group was smaller than the control group,and the difference was statistically significant;The tumor inhibition rate of the 40 m M group was calculated to be 70.6%,and the 10 m M group was 44.5%,with the increase of the concentration of KLK7 small molecule inhibitor,the tumor inhibition effect was more obvious.It was concluded that the tumor formation rate and proliferation ability of subcutaneous transplanted tumors in mice of the experimental group were significantly inhibited compared with the control group after drug intervention.No obvious signal of metastasis of the important organs(heart,liver,spleen,lung,kidney)was found by vision,H&E staining of the tumors was in accordance with the typical pathological changes of PDAC,no obvious signal of metastasis was found in the organs according to H&E staining.Conclusion: The KLK7 small molecule inhibitor previously synthesized by our research group showed tumor suppressive effect in the PDX model of pancreatic cancer with high expression of KLK7,further strengthened the view that KLK7 may be a potential therapy target for pancreatic cancer.