Mitochondrial protein LETM1 and its-mediated CTMP are potential therapeutic targets for endometrial cancer

Leucine zipper/EF hand-containing transmembrane-1 (LETM1) is an important mitochondrial protein, while its function in endometrial cancer remains unknown. This study aimed to explore the function of LETM1 in endometrial cancer and reveal the underlying mechanisms involving carboxy-terminal modulator protein (CTMP). Immunohistochemistry was performed to detect the expression of LETM1 and CTMP in normal, atypical hyperplastic and endometrial cancer endometrial tissues. LETM1 and CTMP were silenced in two endometrial cancer cell lines (ISK and KLE), which were verified by western blot. Cell viability, colony number, migration and invasion were detected by cell counting kit-8, colony formation, wound healing and trans-well assays, respectively. A xenograft mouse model was established to determine the antitumor potential of LETM1/CTMP silencing in vivo. In addition, CTMP was overexpressed to evaluate its regulatory relationship with LETM1 in endometrial cancer cells. The expression of LETM1 and CTMP proteins were higher in endometrial cancer tissues than atypical hyperplastic tissues and were higher in atypical hyperplastic tissues than normal tissues. LETM1 and CTMP were also upregulated in ISK and KLE cells. Silencing of LETM1 or CTMP could decrease the viability, colony number, migration and invasion of endometrial cancer cells and the weight and volume of tumor xenografts. In addition, CTMP was downregulated by LETM1 silencing in KLE cells, and its overexpression enhanced the malignant characteristics of si-LETM1-transfected KLE cells. Silencing of LETM1 inhibits the malignant progression of endometrial cancer through downregulating CTMP.