Role Of Myocyte Enhancer Factor (MEF2D) In Hepatocellular Carcinoma

Background: Hepatocellular carcinoma(HCC)is the main type of primary liver cancer,accounting for 90% of primary liver cancer.Its incidence rate worldwide is increasing year by year.HBV and HCV infection are the main risk factors for the development of HCC,and the most common risk factors for HCC in western countries are nonalcoholic steatohepatitis associated with metabolic syndrome or diabetes.However,hepatocellular carcinoma is the third malignant tumor with the highest mortality in China,and the 5-year survival rate is only 50%-70%.At present,there are some problems in the clinical treatment of liver cancer,such as poor prognosis,easy recurrence and low survival rate.Once found,liver cancer is mostly advanced.Surgical resection,radioablation,arterial chemoembolization or liver transplantation are usually not the feasible choice for the treatment of liver cancer in this case.In this case,systematic treatment with tyrosine kinase inhibitors such as sorafenib has becomed the feasible choice.Tyrosine kinase inhibitors have produced a 30% benefit for patients,but drug resistance was developed after 6 months.Patients face the choice of changing the secondgeneration tyrosine kinase inhibitors.However,large doses of chemotherapeutic drugs will cause irreversible damage to patients’ normal tissues or organs,such as digestive organs,skin tissues and so on.The dosage of traditional chemotherapy drugs is relatively large,so the side effects are relatively large,resulting in the death of normal cells around cancer cells.Relatively speaking,the low dose required to induce tumor cell senescence.Because the senescence cancer cells lose the ability of proliferation and metastasis,the survival time of advanced patients is prolongedThis study first investigated the role of myocyte enhancer factor(MEF2D)in sorafenib resistant liver cancer patients and animals;Then,the effect of low-dose chemotherapeutic drugs on the senescence of liver cancer cells and the role of MEF2 D in senescence liver cancer cells were studied.To explore the role of MEF2 D in the occurrence and development of liver cancer.Objective: In the first part,the drug resistance mechanism of sorafenib in hepatoma cells was further verified by animal experiments and clinical data;The second part is to explore the molecular mechanism of liver cancer cell senescence induced by low-dose chemotherapy drugs such as adriamycin.Methods: In the first part,we verified the overexpression of MEF2 D in liver cancer samples of sorafenib by immunohistochemistry and Western blot.Then PLC / PRF / 5-DR3 cells knockout of MEF2 D and SPRY4 were inoculated subcutaneously in nude mice and divided into sg SPRY4 + Lv-sh MEF2D-1;sg SPRY4+Lv-Scrambled;sg Control+Lvsh MEF2D-1;sg Control + Lv-scrambled.MEF2 D was involved in ERK activation and sorafenib resistance in SPRY4 dependent manner were verified by immunohistochemistry and Western blot.PLC/ PRF/ 5-DR3 were inoculated subcutaneously to nude mice,that HDAC4 inhibitor and sorafenib were given to explore the inhibition of SPRY4 expression level by HDAC4 and MEF2 D complex.The second part is the effect of low-dose chemotherapy drugs such as adriamycin on liver cancer cells and the change of MEF2 D in the liver cancer cells senescence.The SA-β-Gal staining and Western blot were used to study the effect of low-dose adriamycin on the senescence of hepatoma cells.And the subsequent Western blot and RT-PCR showed that the expression of MEF2 D decreased.Through SA-β-Gal staining and Western blot were used to detect the effect of MEF2 D on adriamycin induced hepatoma cells senescence.Results: 1.The overexpression of MEF2 D in sorafenib resistant liver cancer samples was verified in animal experiments and clinical data,and MEF2 D was involved in ERK activation and sorafenib resistance in SPRY4 dependent manner.Inhibition of the expression of SPRY4 by HDAC4 and MEF2 D complex.The combination of HDAC4 inhibitor and sorafenib in the treatment of liver cancer had a significant therapeutic effect.2.When studying the therapeutic effect of low-dose adriamycin on liver cancer,we found that low-dose adriamycin can induce the senescence of liver cancer cells and change the expression level of MEF2 D in senescent liver cancer cells.Further SA-β-Gal staining and Western blot showed that MEF2 D overexpression could inhibit the senescence of hepatoma cells induced by low-dose adriamycin.Conclusions:1.The overexpression of MEF2 D in sorafenib resistance liver cancer samples,and MEF2 D was involved in the activation of ERK pathway in SPRY4 dependent manner.The combination of HDAC4 inhibitor and sorafenib was contributes to the treatment of liver cancer.2.100 n M adriamycin contributes to promote the senescence of liver cancer cells,while the expression of MEF2 D was decreased at the same time.