| Background and purpose:As a common malignant tumor of the endocrine system,thyroid cancer accounts for a large proportion of head and neck tumors,ranking fourth in female malignant tumors.Papillary thyroid cancer accounts for the vast majority.Carnitine acyltransferase 1(CPT1),as a key enzyme in the ?-oxidation pathway,plays an important role in fatty acid catabolism.At present,CPT1 mainly has three family members: CPT1 A,CPT1B,and CPT1 C.As a rate-limiting enzyme that regulates metabolism,more and more studies have found that CPT1 plays an important regulatory role in the metabolic process of tumors.The expression of CPT1 is different in various tissues and cells,and has certain tissue specificity: CPT1 A is widely distributed in most tissues,and is highly expressed in the liver;CPT1B is mainly distributed in muscles;CPT1C is mainly distributed in the brain,the central nervous system,such as the hippocampus,amygdala,and hypothalamic nucleus,plays an important role in cognition and learning,feeding behavior,energy consumption of the body,and endocrine regulation of emotional coping.CPT1C is the only protein in the CPT1 family that can be regulated by p53.AMPK is a key molecule in the regulation of cellular energy metabolism.In order to maintain the normal proliferation and invasion,tumor cells will regulate their energy metabolism processes.AMPK plays a very important role in these processes.The study found that the activation of AMPK can induce the phosphorylation of c AMP response element binding protein(CREB),and promote the nuclear peroxisome proliferation receptor gamma coactivator factor-1?(PGC-1?)activity,increase estrogen-related receptor ?(ERR?),thereby promoting CPT1 C protein expression.Apoptosis,as a basic biological change of cells,participates in the removal of abnormal cells during the growth and proliferation of multicellular organisms.Apoptosis plays an important role in the evolution of the organism and the internal environment.Apoptosis is closely related to the occurrence of various human diseases,especially playing an important role in the formation of tumors.In the occurrence and development of tumors,apoptosis is a double-edged sword.On the one hand,it can target cell death and inhibit the occurrence and development of tumor cells;on the other hand,it can maintainthe survival of tumor cells and suppress the lack of nutrients,Hypoxia,oxidative stress,ionizing radiation,chemotherapy and inflammation damage to tumor cells,improve the viability of tumor cells in adverse environments,which leads to the development of drug resistance.Clinical studies have shown that the activation of apoptosis can promote cancer cell survival and may lead to relapse.However,there is no research on CPT1 C and apoptosis in thyroid cancer.Based on the above research background,we speculate that in thyroid cancer,CPT1 C affects the occurrence and development of thyroid cancer by regulating cell proliferation and apoptosis.This subject intends to study the effect of CPT1 C on biological characteristics of thyroid papillary carcinoma cells,including cell proliferation,apoptosis,migration through cell experiments,molecular biology experiments,clinical sample analysis,and gene interference.We further explore the pathogenic molecular mechanism of papillary thyroid carcinoma to provides a solid theoretical basis and potential drug targets for its early diagnosis and treatment.Chapter 1 The relationship between CPT1 C and the survival of thyroid papillary carcinoma cells under stress conditionsMethods:The research group collected clinical samples of papillary thyroid cancer to compare and analyze the nucleic acid expression of CPT1C;at the same time,the cell activity,cell cycle and apoptosis of thyroid cancer cells were detected after silencing CPT1C;further use different stress stimuli to detect the expression of CPT1 C.Results:1.Among 48 patients,the expression of CPT1 C m RNA in tumors of 34(71%)patients was significantly higher than normal adjacent tissues;2.In the papillary thyroid cancer cell line KTC-1,transfection of si RNA interfered the expression of CPT1 C.The results showed that silencing CPT1 C can inhibit the proliferation and migration of tumor cells,promote the occurrence of apoptosis,and decrease the ratio of G2 / M phase cells,increase the ratio of G1 phase cells;3.In the hypoxic stress model,with the extension of hypoxic time,the expression of CPT1 C in KTC-1 and B-CPAP cells gradually increased;in the hypoglycemic stress model,the decrease in glucose concentration also led to increase expression of CPT1 C in KTC-1and B-CPAP cells gradually;4.After interfering the CPT1 C,the survival rate of cells under hypoxia and low glucose was significantly reduced;overexpression of CPT1 C could significantly improve the survival rate of cells under hypoxia and low glucose conditions.Conclusions:The expression level of CPT1 C m RNA and protein in papillary thyroid cancer tissue was significantly higher than that in adjacent tissues;CPT1C played an important role in regulating the biological characteristics of thyroid cancer cell proliferation,migration,and apoptosis;metabolic stress such as low oxygen and low glucose could upregulate the expression level of CPT1 C in thyroid cancer cells;CPT1C played an important role in regulating the survival of thyroid cancer cells under metabolic stress.Chapter 2 The mechanism of up-regulatiing CPT1 C expression in papillary thyroid cancer cells under metabolic stressMethods:A metabolic stress model was used to detect changes in AMPK-PPAR? pathway;combined with AMPK-specific agonists and inhibitors,the role of AMPK in CPT1 C upregulation was investigated.Results:1.In low-glucose condition,consistented with the increase in CPT1 C expression,the activity of AMPK(p-AMPK level)increased,and the expression level of PPAR? also increased significantly;2.AICAR,an AMPK agonist,increased the intracellular p-AMPK level significantly while up-regulated the intracellular expression level of CPT1C;3.Compound C,an AMPK inhibitor,not only inhibited the activity of AMPK,inhibited expression of PPAR? and CPT1 C,but also significantly inhibited the activation of AMPK and increased expression of PPAR? and CPT1 C under metabolic stress.Furtherly,Compound C promoted the apoptosis of tumor cells and reduces the viability of tumor cells.Conclusions:The activation of the AMPK-PPAR? pathway under metabolic stress is synchronized with the increase expression of CPT1C;the expression of CPT1 C and PPAR? depend on the activation of AMPK.Chapter 3 Regulation of CPT1 C via PPAR? in papillary thyroid cancer cells under metabolic stressMethods:Transfect si RNA to interfere with the expression of PPAR?,and observe the effect on the expression of CPT1 C under metabolic stress;construct a CPT1 C luciferase reporter gene plasmid and observe whether PPAR? can directly promote the transcription of CPT1 C.Results:1.After interfering with the expression of PPAR?,the expression level of CPT1 C in cells was significantly inhibited under normal conditions or under metabolic stress;2.Interfering with the expression of PPAR? had little effect on the apoptosis of cells,but significantly increased the proportion of apoptotic,decreased the viability of tumor cells under metabolic stress;3.Overexpression of PPAR? can significantly increase the transcriptional activity of the CPT1 C promoter.Conclusions:Under metabolic stress,PPAR? could directly act on the CPT1 C promoter and regulate the expression of CPT1 C at the transcription level. |
PDF Full Text Request