Objective   To investigate the expressions of PTEN (gene for phophatase and tensin homolog deletedon chromosome ten)

and changes of microvessel density (MVD) and microlymphatic density (MLD) in gastric cancer

para-cancerous and normal tissues

and analyze their relationship with tumor clinicopathological features and patient survival.  Methods   Tissue microarrays containing gastric normal gastric mucosa (n=32)

para-cancerous tissue (n=54) and gastric cancer (n=189) were prepared and the expression of PTEN was detected by immunohistochemistry. Moreover

MVD and MLD were evaluated within the microarrays by double immunohistrchemistry staining with Ⅷ factor polyclonal antibodies and a D2-40 antibody

respectively. Clinical data were retrospectively analyzed.  Results  The positive rates for PTEN of the gastric carcinoma

para-cancerous and normal tissues were respectively 50.8% (96/189)

85.2% (46/54) and 96.9% (31/32). The positive rate of PTEN  was lowest in the gastric carcinoma among the 3 groups (Chi square=19.330

P=0.000; Chi square=22.830

P=0.000). In gastric cancer tissues

the positive rates of PTEN protein were significantly associated with differentiation

lymph node metastasis

Lauren’s classification (P0.05)

and not associated with sex

age

invasion

and tumor size (P0.05). MVD and MLD were significantly higher in gastric carcinoma than in para-cancerous as well as normal tissues (MVD: 28.84±14.17 vs 17.02±8.54 and 16.69±7.21; MLD: 8.55±4.98 vs 4.05±2.48 and 3.99±1.56

P0.01). MVD was significantly correlated with tumor differentiation

Lauren’s classification and invasion (P0.01). Meanwhile

MLD was significantly correlated with tumor differentiation

Lauren’s classification and lymph node metastasis (P0.05). MVD and MLD were significantly lower in PTEN-positive tumors compared with PTEN-negative tumors (MVD: 31.37±15.14 vs 26.86±13.29

P=0.031; MLD: 9.37±4.23 vs 7.61±5.29

P=0.012). The positive rate of PTEN in the gastric carcinoma were negative correlated with MVD and MLD (r=-0.168

P=0.021; r=-0.283

P=0.000). A survival advantage were noted in the patients with PTEN-positive tumors and lower MVD tumors (P0.05)

but MLD had no such correlation (Chi square=1.044

P=0.307). The positive rates of PTEN protein was an independent prognostic index of type

grade

and stage of the disease (P0.05).  Conclusion  The lower-expression of PTEN is involved in the incidence

development

differentiation

invasion

and metastasis of gastric cancer

and a late incident in gastric cancer. The lower-expression of PTEN can enhance MVD and MLD in gastric cancer. PTEN may be a novel prognostic marker of gastric cancer.