Effect and mechanism of ketogenic diet on tumour growth of EGFR/KRAS gene mutant human lung adenocarcinoma xenograft in nude mice

ZHENG Youmei; PENG Qian; ZHANG Yi; YUAN Qianying; GAO Yongfeng; CHEN Jitao

doi:10.3969/j.issn.1002-266X.2023.32.008

Abstract：Objective To investigate the effects of ketogenic diet on the growth of human lung adenocarcinoma epi-dermal growth factor receptor(EGFR)mutant cell line PC9 and KRAS mutant cell line A549 xenograft tumors in nude mice,and to explore their related mechanism.Methods A549 and PC9 cells in the logarithmic growth phase were inocu-lated subcutaneously into the right forelimbs of nude mice,and we established the nude mouse xenograft tumor model of A549 and PC9.Each type of nude mice was divided into the standard diet group(SD group)and ketogenic diet group(KD group)with 6 mice in each group when the tumor diameter reached 2 mm,and mice in the two groups were fed with SD and KD for 30 days,respectively.The body weight,blood glucose,blood ketone body and tumor size of nude mice were mea-sured regularly.Tumor weight was measured and tumor inhibition rate was calculated on the 30th day of dietary interven-tion.The pathological changes of heart,liver,lung,kidney and brain in xenograft mice were observed.The expression levels of 3-succinyl-CoA transferase 1(OXCT1)and β-hydroxybutyrate dehydrogenase 1(BDH1)genes,which were key enzymes in ketone body metabolism,were analyzed in A549 and PC9 cell lines.The differentially expressed genes in A549/PC9 xenograft tumors of KD group and SD group were screened and KEGG pathway enrichment analysis was per-formed.Results The blood ketone body level in KD group was higher than that in SD group since the 10th day(P<0.05).Compared with the SD group,the tumor volume of A549 xenograft mice in KD group was smaller and the tumor mass was lighter,but the tumor volume of PC9 xenograft mice in the KD group was larger and the tumor mass was heavier(all P<0.05).The tumor inhibition rates of A549 xenograft mice and PC9 xenograft mice in the KD group were 58%and-133%,respectively.No significant pathological changes were observed in the organs of the two types of tumor-bearing nude mice under different intervention conditions.The expression levels of OXCT1 and BDH1 genes in PC9 cells were higher than those in A549 cells.Under different dietary intervention conditions,there was significant difference in gene ex-pression in A549/PC9 xenograft tumors,and there was significant difference in gene expression in tumor tissues between the two types of xenograft nude mice.The differentially expressed genes of A549 xenograft tumors in the KD and SD groups were mainly enriched in cell cycle and JAK-STAT signaling pathways,while the differentially expressed genes in PC9 xeno-graft tumors in the KD and SD groups were mainly enriched in IL-17,Relaxin,AGE-RAGE and NF-κB signaling pathways and other tumor signaling pathways.Conclusions KD inhibits the proliferation of A549 xenograft tumor but promotes the growth of PC9 xenograft tumor.KD intervention induces changes in gene expression profiles and signaling pathways of xenografts of two kinds of lung cancer cells in nude mice.The increased expression of OXCT1 gene and the enrichment of cancer signaling pathways in PC9 xenograft mice may be the reasons for KD promoting tumor proliferation.