FAM107B is regulated by S100A4 and mediates the effect of S100A4 on the proliferation and migration of MGC803 gastric cancer cells.

FAM107B expression was decreased in stomach cancer and many other kinds of cancer. The forced expression of FAM107B in HeLa cells diminished proliferation in response to growth factors, suggesting that FAM107B might play important roles in many types of cancers. But the mechanisms underlying the decreased expression of FAM107B in cancers are not clear, the functional significance needs to be further clarified. Our previous findings from cDNA microarray showed that there are 179 differentially expressed genes after S100A4 inhibition in gastric cancer cells MGC803. FAM107B was an upregulated one among them. In the present study, we confirmed that FAM107B expression was upregulated in MGC803 cells after S100A4 inhibition by qRT-PCR. We demonstrated for the first time that FAM107B was downregulated by S100A4. The results from CCK-8 and transwell assay showed that FAM107B inhibition by siRNA led to significantly increased proliferation and migrating abilities of MGC803 cells, respectively, indicating that FAM107B plays important roles in inhibiting the proliferation and migration of MGC803 cells. The rescue experiment showed that FAM107B-siRNA transfection reversed the reduced proliferation and migration abilities induced by S100A4 inhibition in the cells. These findings suggest that, as a downstream effector, FAM107B at least partly mediates the effect of S100A4 on the proliferation and migration of MGC803 cells. In conclusion, we first provide experimental evidence suggesting that FAM107B was downregulated by S100A4 in gastric cancer MGC803 cells. And FAM107B at least partially mediates the biological effect of S100A4 in the cells.