Abstract: Background and purpose: The gastric cancer is the highest incidence of malignant tumors in the world. The main treatment methods for gastric cancer are operation and chemotherapy. But the effect is not good. With the rapid development of economy and molecular biology, early diagnosis and molecular targeted therapy for gastric cancer has become a research hotspot. The oncogene overexpression and the anti-oncogene lower expression are closely related with gastric cancer. CDC4/FBXW7 is an anti-oncogene, but c-Myc is an oncogene. The previous research showed that CDC4 affected the expression of many oncogenes, such as Cyclin E. This study aimed to investigate the expression of CDC4 and c-Myc in gastric cancer and to elucidate the potential relationship between their expressions and clinical pathological characteristics. Methods: Semi-quantitative reverse transcription polymerase chain reaction (sRT-PCR), immunohistochemistry and Western blot method were used to determine the mRNA and protein expressions of CDC4 and c-Myc in 40 specimens of gastric carcinoma tissues, corresponding adjacent tissues and normal mucosal tissues. The expressions of CDC4 and c-Myc and the clinical pathological characteristics were analyzed. Results: The protein expressions of CDC4 in gastric cancer tissues were significantly lower than those in adjacent tissues and normal mucosal tissues (P<0.05), whereas the protein expression of c-Myc in gastric cancer tissues was significantly higher than that in adjacent tissues and normal mucosal tissues (P<0.05). The protein and mRNA expression of CDC4 and c-Myc were correlated with differentiation, TNM stage, lymph node metastasis, infiltration, but not with patients’ gender, age and site of cancer (P<0.05). There was a significant negative correlation between CDC4 and c-Myc at the mRNA and protein expression levels (P<0.05). Conclusion: The lower expression of CDC4 is correlated with differentiation, TNM stage, lymph node metastasis and infiltration. c-Myc overexpression is likely to be the CDC4 loss. It suggests that the loss of CDC4 may be a valuable marker for assessing the diagnosis and treatment and the prognosis of gastric cancer.

Key words: CDC4, c-Myc, Immunohistochemistry, Semi-quantitative reverse transcription polymerase chain reaction, Western blot