Selective Inhibitors Of Protein Tyrosine Phosphatases

Protein tyrosine phosphatase(PTPs)can catalyze the dephosphorylation of protein tyrosine phosphorylation residues and influence processes such as cell growth,proliferation,migration,differentiation and apoptosis.Current studies have found that there are 107 kinds of PTPs in human body.SHP-2,PRL-3 and PTP1B,as important members of protein tyrosine phosphatase(PTPs),are closely related to the occurrence and development of many diseases.For example,the overexpression of SHP-2 can lead to thyroid cancer,non-small cell lung cancer,liver cancer and breast cancer;PRL-3 is highly expressed in colorectal cancer,liver cancer and ovarian cancer;abnormal expression of PTP1B may lead to diabetes and obesity.PTPs are therefore emerged as new drug targets to treat related diseases,and PTPs selective inhibitors have been attracting great interest.This work intends to develop potent and selective PTPs inhibitors for the treatment of related diseases.The specific research work is as follows:1.In the second chapter of the thesis,we successfully constructed the strain of pET28a-ΔPRL-3 GENE+E.coli BL21 and screened out the best conditions for the strain to express recombinant protein,so as to purify PRL-3 protein.In addition,SHP-2,PTP1B and TCPTP proteins were purified.2.In the third chapter of the thesis,four Ce(Ⅲ)complexes 1-4 based on Schiff base ligands were designed,synthesized and characterized.Analysis on the inhibition of these four Ce(Ⅲ)complexes against four PTPs(SHP-1,SHP-2,TCPTP and PTP1B)indicated that Ce(Ⅲ)complex 3 strongly and selectively inhibited the activity of SHP-2 with the IC50 value of 0.61 μM.At the cellular level,Ce(Ⅲ)complex 3 decreased expression of SHP-2 and promoted the phosphorylation of the SHP-2 substrate.Ce(Ⅲ)complex 3 either decreased the survival rate of A549 cells and induced apoptosis.All these results suggested that Ce(Ⅲ)complex 3 was a potential bifunctional inhibitor against the activity and expression of tyrosine phosphatase SHP-2.3.In the fourth chapter of the thesis,we designed and synthesized six rhodanine derivatives 5-10.Rhodanine derivative 8 could potently inhibit the activity of PRL-3,and its IC50 value was 15.22μM.The interaction between rhodanine derivative 8 and PRL-3 by fluorescence spectroscopy demonstrated that they could be well combined with a binding constant of 1.74×106 M-1 and a binding ratio of 1:1.After SW-480 cells were treated with rhodanine derivative 8,we found that rhodanine derivative 8 could selectively decrease the expression of PRL-3 protein and increase the phosphorylation level of PRL-3 substrates,inhibit the proliferation of SW-480 cells and induce its apoptosis.The results revealed that compound 8 was a bi-functional inhibitor against the activity and expression of PRL-3 and a promising anti-tumor candidate targeting PRL-3.4.In the fifth chapter of the thesis,we designed and synthesized a series of isoniazid derivatives 11-16 and their corresponding copper complexes 17-22.Analysis on their inhibition against PRL-3,PTP1B and TCPTP showed that isoniazid derivatives 11-16 had no inhibitory effect on the three PTPs,while their corresponding copper complexes 17-22 strongly inhibited these enzymes.Their inhibitory effect on PTP1B with IC50 values of 0.31-0.39μM was obviously stronger than against PRL-3 and TCPTP,displaying some selectivityon PTP1B.