Preliminary study on the inhibitory effect of tumor suppressor gene KPC1 on the proliferation in gastric carcinoma cell

BACKGROUND: To investigate Kip1 ubiquitination-promoting complex 1 (KPC1) expression and its relationship with NF-κB p50 in gastric cancer cell lines. METHODS: The expression of KPC1 and NF-κB p50 in tissue samples from 159 gastric cancer patients after tumor resection and normal gastric mucosa samples from 56 patients as negative controls was retrospectively studied. The relationship between KPC1, NF-κB p50, and clinicopathological factors was analyzed, and the correlation between KPC1 and cytoplasmic NF-κB p50 was determined. The expression level of KPC1 and NF-κB p50 was researched using reverse transcription (RT) polymerase chain reaction (RT-PCR) and Western blotting in 3 differentiated human gastric cancer cell lines (AGS, SGC-7901 and MGC-803). RESULTS: Immunohistochemistry indicated that KPC1 and NF-κB p50 expression was significantly decreased in gastric cancer cases, and the level of expression varied across the differentiated gastric cancer tissues. KPC1 and NF-κB p50 expression was significantly connected with tumor differentiation, tumor-node-metastasis (TNM) staging, and metastasis of 159 patients suffering from gastric cancer (P<0.05), but not correlated with age and lesion size (P>0.05). KPC1 was positively connected with the expression of NF-κB p50 by the Spearman correlation analysis (r=0.427, P<0.05). The expression of KPC1 and NF-κB p50 mRNA was reduced, and there were differences in the 3 differentiated human gastric cancer cell lines, as confirmed by western blotting. CONCLUSIONS: The co-expression of KPC1 and cytoplasmic NF-κB p50 in gastric cancer promotes tumor suppressor gene expression. Therefore, limiting the growth of tumor cells may inhibit the development of gastric cancer.