The IZUMO protein family comprises Izumo sperm-egg fusion protein 1 (IZUMO1), IZUMO2, IZUMO3, and IZUMO4, which contain an N-terminal IZUMO domain [1]. IZUMO1, IZUMO2, and IZUMO3 are expressed in the testes and sperm cells, whereas IZUMO4 is a soluble protein expressed in the testes and other tissues [1]. In addition, sperm acrosome-associated 6 and transmembrane protein 95 expressed in the testes contain an IZUMO domain‐like motif and participate in sperm-oocyte fusion [1], [2].

The function of IZUMO1 in mammalian fertilization has been extensively studied [3], [4]. After the acrosome reaction, IZUMO1 relocates to the equatorial segment, which overlies the sperm plasma membrane, and then binds to the oocyte receptor JUNO [5]. Although less is known about IZUMO2 function, a recent in silico analysis has identified IZUMO2 as a prognosis-related methylation-driven gene (MDG) [6]. However, it remains unclear whether IZUMO2 protein expression is suppressed or overexpressed in colorectal cancer cells.

In the present study, we aimed to determine IZUMO2 expression in colorectal cancer in relation to clinicopathological features.