Authors:D. Zhu, R. He, W. Yu, C. Li, H. Cheng, B. Zhu, and J. Yan
Hypoxia is a pivotal initiator of tumor angiogenesis and growth through the stabilization of hypoxia-inducible factors (HIFs). This study set out to examine the involvement of HIF-1α and HIF-2α in colon cancer and ascertained whether ORAI3 was involved in the pathway.
Materials and methods
Patients and murine models as well as human colorectal adenocarcinoma tumor (CW2) cells were included to examine the levels of ORAI1/3 and HIF-1/2α levels. Calcium imaging was utilized to ascertain the activity of calcium channel. Scratch assay was used to assess the migration capacity of the cells.
Tumors from murine colon cancer xenograft models and patients with colon cancer displayed high ORAI1/3 and HIF-1/2α levels. Hypoxia treatment, mimicking the tumor microenvironment in vitro, increased ORAI1/3 and HIF-1/2α expression as well as store-operated Ca2+ entry (SOCE). Of note is that HIF-1/2α silencing decreased SOCE, and HIF-1/2α overexpression facilitated SOCE. Furthermore, ORAI3 rather than ORAI1 expression was inhibited by HIF-1/2α silencing while increased by ML228. Luciferase assay also confirmed that ORAI3 was elevated in the presence of ML228, indicating the linkage between HIF-1/2α and ORAI3. Additionally, colony-forming potential and cell migration capacity were decreased in siHIF-1α and siHIF-2α as well as siORAI3 cells, and the facilitating effect of ML228 on cell migration and colony-forming potential was also decreased in siORAI3 CW-2 cells, which points out the importance of ORAI3 in HIF1/2α pathway.
Our findings allow to conclude that both HIF-1α and HIF-2α facilitate ORAI3 expression, hence enhancing colon cancer progression.