Abstract: Objective To investigate the correlation between infection with L-form of Helicobacter pylori (Hp-L) and the
expressions of macrophage migration inhibition factor (MIF), matrix metalloproteinase 9 (MMP9), and vascular endothelial
growth factor (VEGF) in gastric cancer. Methods Hp-L was examined in 80 gastric carcinoma and 50 adjacent normal tissues
by Gram staining and immunohistochemical staining, and the expressions of MIF, MMP9 and VEGF were detected by
immunohistochemical staining; the expression of MIF mRNA was detected by RT-PCR and the expression of MIF, MMP9 and
VEGF proteins were detected by Western blotting in 30 fresh gastric cancer tissues and the corresponding adjacent tissues.
Results Of the 80 gastric carcinoma tissues, 57 (71.25% ) showed Hp-L positivity detected by both Gram staining and
immunohistochemical staining, as compared with a rate of only 14% in the adjacent normal tissues (P<0.05). The gastric
carcinoma tissues showed higher expression levels of MIF, MMP9 and VEGF proteins than the corresponding adjacent normal
mucosa; the positivity MIF, MMP-9 and VEGF proteins were significantly higher in Hp-L-positive gastric carcinoma than in
Hp-L-negative cases (P<0.05). Positive correlations were found between Hp-L positivity and the expressions of MIF, MMP-9
and VEGF (r=0.598, 0.292, 0.341, respectively, P<0.05). The 30 fresh gastric cancer tissues showed also significantly higher MIF
mRNA expression and MIF, MMP-9 and VEGF protein expressions than the adjacent tissues (t=3.729, P<0.01). The expressions
of MIF and MMP-9 were also related to the clinicopathological factors including lymph node metastasis and depth of invasion
(P<0.05). Conclusion Infection with L-form of Hp-L can be an important factor that contributes to the invasion and metastasis
of gastric carcinoma, the mechanism of which involves up-regulated expressions of MIF, MMP-9 and VEGF.