The Study Of Anti-breast Cancer Activity Of Noxa Derivatives As Novel Microtubule Inhibitors

Microtubules,as one of the widespread cytoskeletons in eukaryotic cells,are involved in the establishment of complex intracellular connections.Their highly dynamic kinetic structural properties determine their diverse biological functions:cell morphological support,participation in cell motility,and involvement in intracellular material transport.The most important biological function of microtubules is to participate in the assembly of spindle during mitosis.It is based on this biological function that microtubule-targeted drugs inhibit spindle assembly during mitosis of tumor cells,thus inhibiting tumor cell proliferation and inducing catastrophic mitotic death.Currently,microtubule drugs have become one of the most successful chemotherapeutic strategies in recent years,including colchicine,a microtubule polymerization inhibitor,vincristine,and paclitaxel,a microtubule stabilizer.Microtubule drugs have been used as chemotherapeutic agents for the treatment of various solid tumors and hematologic tumors due to their broad spectrum antitumor activity,among which breast cancer is the main clinical indication for many types of microtubule drugs,and several microtubule drugs have become first and second line treatment strategies for breast cancer in adjuvant surgery and combination therapy.Due to the failure of endocrine and targeted therapies in the treatment of triple-negative breast cancer with higher mutation rate and malignancy,microtubule drugs including paclitaxel and vincristine have become the most important drug treatment strategy for triple-negative breast cancer in clinical practice.Therefore,it is important to find new microtubule-targeted drugs with low toxicity and high efficiency for the treatment of breast cancer,especially triple-negative breast cancer.The core work of this thesis is as follows:In vitro screening of a group of Noxa active derivatives with similar structure and strong anti-proliferative activity against breast cancer:N-18,N-28,N-33,N-3 8 and N-40;further cell line selectivity evaluation revealed that this group of Noxa active derivatives had higher selectivity for proliferation inhibition against triple negative breast cancer cell line MDA-MB-231.The representative compounds with higher proliferation inhibitory activity,N-38 and N-40,were less toxic to kill human normal breast cells and renal epithelial cells than the clinical drugs Taxol and Vincristine.The evaluation revealed that the drug safety window of N-38 in MDA-MB-231 cell lines and human normal cell lines was comparable to that of clinical drugs.Meanwhile,the results of multiple experiments revealed that this group of Noxa-active derivatives effectively induced mitotic cycle arrest in breast cancer cells and also showed higher cycle arrest selectivity in triplenegative breast cancer cell line MDA-MB-231.Further studies showed that N-38 and N-40,representative compounds of this group of Noxa-active derivatives,competitively bound to colchicine at the microtubule protein colchicine site in vitro and effectively inhibited microtubule polymerization both in vitro and at the cellular level.At the cellular level,they inhibit the normal assembly of spindle during mitosis,thus inducing breast cancer cells to stall at mid mitotic phase and further inducing endogenous pathway apoptosis.In summary,a novel set of colchicine binding site microtubule polymerization inhibitors with lower toxicity were screened in this thesis,which exerted antiproliferative activity by inhibiting spindle assembly to induce mitotic cycle arrest and endogenous pathway apoptosis in breast cancer cells,and showed more sensitive selectivity for triple-negative breast cancer cell lines.This work brings a new active group for the study of microtubule polymerization inhibitors,and at the same time,this series of compounds is relatively simple and easy to synthesize,which is expected to be a new experimental tool as cell cycle synchronization reagents.In addition,this series of compounds is expected to be further optimized and developed as novel microtubule chemotherapeutic agents for the treatment of breast cancer,especially triple-negative breast cancer with higher malignancy and even broad spectrum of tumor types.