The Drug Development And Applications Of Histone Methyltransferases NSD3 And CARM1 In Antitumor

The occurrence and development of cancers is the result of a combination of genetics and epigenetics.Histone methylation is an important kind of epigenetic modification and abnormalities of associated modifying enzymes is the characteristic of numerous tumors.Therefore,targeting histone methyltransferases is an important anti-tumor drug development strategy.This thesis focuses on the histone lysine methyltransferase nuclear receptor binding SET domain protein 3(NSD3)and coactivator associated arginine methyltransferase 1(CARM1)to develop lead drugs for the sensitive tumor types and modes of action of these targets.The first part focuses on drug development around NSD3,a member of the NSD family of histone lysine methyltransferases that catalyze the onset of H3K36me3.Although NSD3 is aberrantly amplified in a variety of tumors,the development of its targeted drugs is still in its infancy.The existing NSD3 chemical probe BI-9231,which blocks the biological function of NSD3 by specifically binding to its prolinetryptophan-tryptophan-proline-1 structural domain,can only inhibit the proliferation of some hematoma cells such as MOLM-13 and is ineffective against other tumors.In this study,we found that knockdown of NSD3 could inhibit the proliferation of lung cancer cells with aberrant NSD3 amplification,such as NCI-H1703 and H520 lung cancer cells.Therefore,a series of NSD3 degraders were synthesized using the probe BI-9231 as the parent core.The active compound 8 was obtained by screening the candidate compounds in terms of proliferation inhibition and NSD3 degradation efficiency.Further studies revealed that compound 8 could specifically degrade NSD3 via the proteasome in a time-dependent and dose-dependent manner without affecting other proteins of the NSD family.In the exploration of the way in which the degrader exerted its effects,it was found that compound 8 could down-regulate the cell cycle-related CDC25 A and anti-apoptotic proteins MCL-1and Bcl-XL,further induce cell cycle arrest and apoptosis.A549 lung cancer subcutaneously transplanted tumor model in nude mice was established,and the expression of NSD3 in tumor tissue was detected after intraperitoneal injection of compound 8(100 mg/kg)for 36 h;finally,it was found that compound 8 could also exert degradation effect in vivo.In conclusion,this part of the study developed specific NSD3 degraders that can effectively degrade target proteins at both cellular and animal levels,and its further optimization has the potential to become new drugs for clinical treatment of lung cancer.The second part focuses on drug development around CARM1,which belongs to type I histone arginine methyltransferases(PRMTs),which can catalyze the asymmetric dimethylation of arginine at position 17 or 26 of histone H3.The expression of CARM1 in kidney cancer is significantly higher than that in normal tissues,and patients with higher expression of CARM1 have a worse prognosis.In this study,the compounds modified with ethylenediamine CARM1 inhibitors were screened,and the compound C-31,which has better proliferation inhibitory activity against kidney cancer compared with existing inhibitors of CARM1,was obtained.It could effectively inhibits CARM1 methyltransferase activity and the growth of A498 kidney cancer subcutaneous graft tumors.Meanwhile,this study found that the activation of p38-MAPK pathway was the reason why some kidney cancer cells were resistant to CARM1 inhibitors.Combining CARM1 inhibitor with SB203580,a pan-inhibitor of p38 pathway,could inhibit cell autophagy,induce apoptosis and sensitize resistant cells to CARM1 inhibitors.Therefore,this part of the study obtained compound C-31 with excellent proliferation inhibitory activity against kidney tumor in vitro and in vivo,further developed a feasible combination drug strategy for drug-resistant kidney cancer cells to expand the potential clinical application of CARM1 inhibitors.