| Backgrounds: Gastric cancer is the fifth most common type of cancer worldwide and one of the common malignant neoplasms in the digestive system,with a high incidence and mortality.Helicobacter pylori(Hp)infection is closely related to the occurrence of gastric cancer.Cysteine synthase β(CBS)is the rate-limiting enzyme in the mammalian sulfur metabolism pathway.Currently,studies have reported that high expression of CBS is associated with various cancers.Deregulating cellular energetics is one of the widely recognized biological characteristics of cancer,and there have been studies exploring the relationship between the expression of CBS and abnormal energy metabolism.However,the expression of CBS in different gastric diseases is still unclear.This study aims to investigate the expression of CBS during the progression of gastric cancer,its correlation with Hp infection,and its biological role.Methods : The study includes 429 paraffin-embedded gastric mucosal tissue specimens and 22 fresh gastric mucosal samples from patients attending the First Affiliated Hospital of China Medical University.The expression of CBS among different gastric diseases was detected by real-time PCR and immunohistochemistry to investigate its relationship with clinicopathological parameters and prognosis.In vitro,AGS and GES-1 cell lines stably overexpressing CBS were obtained by lentiviral transfection,and transcriptome sequencing was performed to clarify the possible biological functions involved in CBS.The changes in cellular ATP,pyruvate and lactate levels were detected.Using the Hp co-culture AGS,GES-1 model,we clarify the relationship between Hp infection and the effects of CBS on cellular ATP,pyruvate and lactate levels.Results:1)Real-time quantitative PCR results showed that CBS mRNA expression was higher in the gastric cancer group than in the adjacent normal group(P=0.036).Immunohistochemical results showed that CBS protein was mainly expressed in the cytoplasm,and the expression trend among different gastric diseases was GS<IM-GA<EGC,NGC<GC;CBS expression was significantly correlated with Hp infection,male,and elderly(P=0.040,P=0.007,P<0.001),and also with TNM stage(P=0.020).High CBS expression suggested a poorer prognosis for gastric cancer patients.2)Transcriptome sequencing analysis of CBS overexpressed AGS cells revealed that differentially upregulated genes were mainly involved in the functional roles of the respiratory electron transport chain,oxidative phosphorylation,cellular respiration,and ATP metabolic processes.The differentially down-regulated genes were mainly involved in biological behaviors such as Henle adrenal ring development,regulation of mitotic spindle organization,and positive regulation of mitochondrial autophagy.3)Furthermore,in vitro cytological experiments revealed that in AGS cells,ATP and pyruvate levels were elevated in the CBS overexpression group(P<0.001,P<0.001)and no significant changes were seen in lactate levels;the inhibitor AOAA decreased ATP and pyruvate(P<0.001,P<0.001)and upregulated lactate levels(P<0.001).In GES-1 cells,ATP and lactate levels were elevated in the CBS overexpression group(P<0.001,P<0.001),while no significant changes were seen in pyruvate levels;the inhibitor AOAA blocked changes in lactate levels(P<0.001),elevated pyruvate levels(P<0.001)and tended to reduce ATP levels.4)Hp stimulation can cause CBS protein expression(AGS: P=0.006),with elevated ATP and pyruvate levels(P<0.001,P=0.020)and decreased lactate levels(P<0.001)in AGS cells;in GES-1 cells,ATP levels were elevated(P=0.037)and no significant changes were seen in pyruvate and lactate levels.Under Hp infection with concomitant addition of the inhibitor AOAA,elevated CBS protein expression was suppressed(AGS: P=0.043),and in AGS cells,ATP levels were reduced(P=0.004)and lactate levels were increased(P<0.001)with a tendency to reduce pyruvate levels;in GES-1 cells,ATP levels were reduced(P<0.001),pyruvate levels were increased(P<0.001)and lactate levels was decreased(P<0.001).Conclusion:The expression of CBS increases gradually with the progression of gastric disease,and high expression of CBS is significantly associated with Hp infection,male gender,and advanced age.The genes associated with high expression of CBS participate in biological functions such as the respiratory electron transport chain,oxidative phosphorylation,cell respiration,and ATP metabolism.High expression of CBS promotes cell energy metabolism,enhances glucose metabolism in normal gastric cells,and attenuates glucose metabolism in gastric cancer cells.These regulatory functions are associated with Hp infection. |
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