The roles of serum PDCD5 in circulating CD133 positive cells of the patients with gastric cancer.

Cancer stem cells are responsible for the development, metastasis, recurrence, and drug resistance of cancer. More and more studies exhibited that the circulating CD133 ⁺ cells is a marker for the prognosis of various malignancies. Programmed cell death protein 5 (PDCD5) can promote apoptosis in different tumor cell types in response to various stimuli. However, the impact of PDCD5 on circulating CD133 ⁺ cells of gastric cancer patients remains unclear. In this study, we detected serum PDCD5 level in blood samples of the patients with gastric cancer by using ELISA. MTT assay, sphere assay, and wound healing assay were used to test the anti-tumor effects of rhPDCD5 on CD133 ⁺ cells in vitro. Lower serum levels of PDCD5 protein were identified in the gastric cancer patients that with CD133 ⁺ fraction more than 1.6 %. No difference between healthy controls and the gastric cancer patients that with CD133 ⁺ fraction less than 1.6 %. Serum PDCD5 was correlated with the favorable prognosis of patients with gastric cancer. In the last, we confirmed that rhPDCD5 could induce apoptosis, and inhibit the proliferation, colony formation, and mobility of CD133 ⁺ cells in vitro by suppressing MEK/ERK pathway. Serum PDCD5 could be considered as a potential drug for the gastric cancer patients with circulating CD133 ⁺ cells.