The Study On Mechanism Of Acetylation Induced PEPCK Iso-enzymes Transition In Liver Cancer Targeted Therapy

HCC is the 3rd cause of cancer-related mortality worldwide while its incidence ranks 7th among all malignant tumors,and the median overall survival time of HCC is only 8-26 months.Diagnosis at advanced stage of most patients is one reason for its short survival time.Sorafenib is the most widely used and only(2008-2017)proved first-line treatment for advanced HCC,but only 10%of patients are sensitive to sorafenib treatment,the low effective rate and high resistance rate causing that sorafenib only provides 2.8-month benefit to overall survival.So,finding biomarkers for sorafenib treatment sensitivity and co-targets of sorafenib is very valuable and emergency for HCC treatment.We established a sorafenib resistant HCC cell sub-line,which was then analyzed by proteomics,phosphoryl-proteomics and acetyl-proteomics.Our muti-proteomics data highlights that mTOR activating and metabolism reprograming contribute to sorafenib resistance,one of the proteins whose protein level and acetylation level are both up-regulated in resistant cells is PCK2,the first rate-limiting enzyme in gluconeogenesis,which is reported to influence mTOR and metabolism reprograming.We found that the high expression of PCK2 in sorafenib resistant cells promotes sorafenib resistance,mTOR activity and mitochondrial respiration rate,knocking down or inhibiting PCK2 reduced sorafenib resistance at cells and CDX models level.At clinical level,we found that high expression of PCK2 is positive correlated with high recurrence probability of HCC.Talking about molecular mechanism,the up-regulation of PCK2 in resistant cells is due to its higher stability,which is caused by its higher acetylation level,specifically,KAT8 acetylates K491 of PCK2 to promote its stability by avoiding lysosome related degradation.Taking together,we firstly reported that PCK2 is involved in sorafenib resistance,and high expression of PCK2 in HCC may indicates high recurrence rate.Inhibiting PCK2 is a potential way to reduce sorafenib resistance.In a word,our data enriched the knowledge that how protein acetylation affects drug resistance of HCC and provided a potential co-target for sorafenib treatment.