Objective  To investigate the protein expression level of lysosome-associated transmembrane protein 4β-35(LAPTM4B-35)and matrix metalloproteinase-9(MMP-9)in gastric cancer(GC)and to determine the relationship of LAPTM 4B-35 or MMP-9 expression with clinicopathological characteristics and prognosis of patients with GC.

  Methods  The messenger RNA(mRNA)expression levelof LAPTM4B-35 and MMP-9 was detected by real-time quantitative polymerase chain reaction, while the protein expression level ofLAPTM 4B-35 and MMP-9 in GC tissues was analyzed by immunohistochemistry in formalin-fixed samples from 152 patients with GC, and data analysis was performed using statistical methods.

  Results  The mRNA expression level of both LAPTM4B-35 and MMP-9 inHGC-27, SGC 7901, and MGC803 GC cell lines was higher than that in the GES-1 normal gastric mucosa cell line.LAPTM 4B-35 andMMP-9 proteins mainly localized in the cytoplasm of GC cells.The positive LAPTM4B-35 expression ratio in GC tissues was 50.7%, while the MMP-9 positive ratio was 36.8%.LAPTM4B-35 and MMP-9 were positively related to gastric cancer.Lauren's classificationand T stage were identified as the relative factors of LAPTM4B-35 expression, while tumor size and N stage were identified as the relative factors of MMP-9 expression in GC tissues.Cox analysis indicated that the degree of differentiation, N stage, LAPTM 4B-35 expression, and MMP-9 expression were independent prognostic indicators for patients with GC.

  Conclusion  LAPTM4B-35 and MMP-9 playimportant roles in the aggressiveness of GC, and LAPTM4B-35 and MMP-9 may be promising indicators for the prognosis of patientswith GC.