Icariin induces apoptosis in mouse MLTC-10 Leydig tumor cells through activation of the mitochondrial pathway and down-regulation of the expression of piwil4

Abstract

Abstract. The Leydig cell tumor, derived from interstitial cells, is a rare neoplasm. In most cases, Leydig cell tumors are benign, however, if the tumor is malignant, no effective treatments are currently available. In this study, we aimed to evaluate the effects of icariin on the growth of the mouse Leydig tumor cell line MLTC-1 and to examine its underlying mechanism. Icariin caused a dose-dependent decrease in the viability of MLTC-1 cells, which coincided with an increase in cell apoptosis through regulation of the expression of Bcl-2/Bax and cytochrome c, activation of caspase-9 and -3. Moreover, the pro-apoptotic effect of icariin on MLTC-1 cells is related to piwil4, since icariin induced a decrease in piwil4 protein expression and piwil4 silencing significantly enhanced the cytotoxic effects of icariin in MLTC-1 cells. These findings suggest a novel anticancer effect of icariin in Leydig cell tumor through activation of the mitochondrial pathway and down-regulation of the expression of piwil4. IntroductionTesticular neoplasms include germ cell tumors and sex cord-stromal tumors. Germ cell tumors comprise 95% of all testicular neoplasms, while the remaining 5% of testicular tumors are sex cord-stromal tumors, which are derived from somatic cells, Sertoli and Leydig cells. The Leydig cell tumor is classified as an interstitial cell tumor, which are commonly benign; however, in adults, ~10% of cases are malignant (1-4). The etiology of Leydig cell tumor in humans remains unknown. Currently, in most cases, the standard therapy for benign Leydig cell tumors is considered to be orchiectomy. Recently, by retrospectively analyzing the long-term follow-up of a series of patients with Leydig cell tumors electively treated with testis sparing surgery, Glannarin et al (5) demonstrated that testis sparing surgery with frozen section examination has an excellent long-term oncological outcome. Therefore, testis-sparing surgery may be chosen for treating benign Leydig cell tumors to maintain fertility, especially in boys and young men (5-9). If the tumor is malignant, orchiectomy with retroperitoneal lymph node dissection is recommended, since chemotherapy and radiation therapy show limited efficacy in the treatment of malignant Leydig cell tumors. Survival time of patients with this malignancy range from 2 months to 17 years, and the mean survival time is 2 years (10,11). To improve the survival time of patients with malignant Leydig cell tumor, and to decrease the serious consequences, such as testicular dysfunction and infertility that is caused by the current treatment for benign Leydig cell tumors, alternative treatments need to be explored.Icariin (C 33 H 40 O 15 ; molecular weight, 676.67), a flavonoid isolated from Herba Epimedii, is considered to be the main active component responsible for the actions of Herba Epimedii. Many studies have shown that it has a wide range of pharmacological and biological activities on endocrine, cardiovascular, genital, bronchial, urinary and immune systems (12)(13)(14)(15). In ...

Anti-Cancer Properties of the Naturally Occurring Aphrodisiacs: Icariin and Its Derivatives

“…Generally, the apoptotic effect of icariin and its derivatives has been associated with the activation of the intrinsic pathway of apoptosis. Treatment with icariin and icaritin has resulted in increase in Bax/Bcl2 ratio, release of cytochrome c, cleavage of poly (ADP-ribose) polymerase and activation of caspases in a wide range of cancer cells (He et al, 2010 ; Li et al, 2010 , 2013a , 2014b ; Tong et al, 2011 ; Wang et al, 2011a ; Zhu et al, 2011 ; Sun et al, 2015b ; Wu et al, 2015b ); these can be regulated by various signaling pathways, as shown in Table 1 . Similarly, icariside II has been shown to increase the ratio of Bax/Bcl2, causing transposition of cytochrome c and activation of caspase-3 and -9 in cancer cells including lung cancer cells and acute myeloid leukemia cells.…”

Effects of Icariin on Reproductive Functions in Male Rats

“…Icariin (C 33 H 40 O 15 ; molecular weight: 676.67), a flavonoid isolated from Herba epimedii , is considered to be the main active component responsible for the actions of the plant . H. epimedii has been proven to be an effective remedy for cardiovascular diseases, osteoporosis, and tumors; moreover, and it can improve endocrine, immune, and cognitive functions [1,2,3,4,5,6,7,8]. In addition, H. epimedii has been traditionally used in China to treat erectile dysfunction [9].…”

Icariin displays anticancer activity against human esophageal cancer cells via regulating endoplasmic reticulum stress-mediated apoptotic signaling

“…Icariin sensitizes cells to TRAIL-induced apoptosis by suppressing NF-κB-dependent c-FLIP expression 50 . Furthermore, icariin treatment decreases PIWIL4 protein expression, which increases apoptosis by regulating the expression of Bcl2/Bax and cytochrome c and the activation of Caspase 9 and 3 in MLTC-1 cells 30 . Although there have been reports concerning the anticancer effect of icariin in some tumors, the effect of icariin on human esophageal cancer and the mechanisms responsible for these effects are not fully understood.…”

“…It has been suggested that Bcl2 (anti-apoptotic) and PUMA (pro-apoptotic) act as opposing members of the Bcl2 family and that these two molecules ultimately regulate cell death in response to ERS 29 . Previous studies have shown that ICA induces the apoptosis of mouse MLTC-10 Leydig tumor cells by regulating the Bcl2 signaling pathway 30 . Furthermore, adenosine inhibits cell proliferation, increases GRP78 and NF-κB p65 expression and induces apoptosis by CHOP and caspase-4 pathways in EC109 cells, which is involved in the ERS pathway 31 .…”