The methanolic extract of Guibourtia tessmannii (caesalpiniaceae) and selenium modulate cytosolic calcium accumulation, apoptosis and oxidative stress in R2C tumour Leydig cells: Involvement of TRPV1 channels.

This study evaluated the effects of the methanolic extract of Guibourtia tessmannii (GT) and selenium (Se) on cell viability, intracellular calcium concentration ([Ca2+ ]i ), apoptosis and oxidative stress through transient receptor potential vanilloid 1 (TRPV1) channel activity in CCL-97 (R2C) tumour Leydig cells. The cells were divided into nine groups and treated as follows: (a)-Control, (b)-Capsazepine (CPZ, 0.1 mM, a TRPV1 channel blocker), (c)-Capsaicin (CAP, 0.01 mM, a TRPV1 channel activator), (d)-GT (500 µg/ml), (e)-GT+CPZ, (f)-GT+CAP, (g)-Se (200 nM), (h)-Se+CPZ and (i)-Se+CAP. After treatments, cell viability, [Ca2+ ]i , apoptosis, caspase 3/9, reactive oxygen species (ROS) and mitochondrial membrane depolarisation (MMD) were evaluated. The [Ca2+ ]i , apoptosis, caspase 3/9, MMD and ROS levels were significantly (p < 0.001) increased in CAP group, but lowered in CPZ group. Interestingly, these parameters were significantly (p < 0.001) improved by GT and Se, compared to the CAP group. Moreover, the co-administration of GT+CAP or Se+CAP inhibited the cytotoxicity of CAP. Thus, the modulatory properties of GT and Se on Ca2+ influx, apoptosis and oxidative stress require the integrity of TRPV1 channel in CCL-97 Leydig cells. These results suggest that GT and Se might be used in the management of cytotoxicity in the testes, involving TRPV1 channel activity.

Testosterone production by a Leydig tumor cell line is suppressed by hyperthermia-induced endoplasmic reticulum stress in mice.

AIMS: Leydig cells are characterized by their ability to produce testosterone. When the Leydig cells are unable to produce enough testosterone, spermatogenesis fails completely. Considering this, it is of great interest to investigate whether the expressions of steroidogenic enzymes are affected by testicular heat stress. This study aimed to demonstrate that heat induced ER-stress significantly influences steroidogenic enzyme expression and testosterone production in the Leydig cells. MAIN METHODS: C57BL/6 mice were subjected to repetitive testicular heat-treatment at 42 °C for 15 min per day, and heat-treated mLTC-1 cells following hCG treatment for 1h. The protein and RNA expressions were measured by Western blot, RT-PCR. The testosterone and progesterone levels were detected by EIA. The histological and pathological characteristics using hematoxylin and eosin (H&E) and antibody stains. KEY FINDINGS: The 3ß-HSD expression was decreased by heat-stress and hCG treatment. While the GRP78/BiP and CHOP levels were increased by ER-stress inducers, those of the steroidogenic enzyme and progesterone were decreased. In contrast, an ER-stress inhibitor rescued the testosterone levels, even under heat-stress conditions. Moreover, the Leydig cells were randomly scattered, and severely damaged upon repetitive testicular heat-treatment. Additionally, immunohistochemical analyses revealed that cleaved caspase-3 was elevated in the testicular Leydig cells, and rescued by TUDCA. Thus, repetitive testicular heat-treatment in mice promotes excessive ER-stress, thereby leading to apoptosis of the Leydig cells and thus, decreased testosterone production. SIGNIFICANCE: Our findings help to provide an ER-stress mediate mechanistic explanation to the impairment of spermatogenesis upon elevation of the testicular temperature.

Role of oxygen in the regulation of Leydig tumor derived MA-10 cell steroid production: the effect of cobalt chloride.

We have earlier shown that cobalt chloride (CoCl2)-induced hypoxia and second messenger 8-bromoadenosine 3', 5'-cyclic adenosine monophosphate (8-Br-cAMP) stimulates vascular endothelial growth factor (VEGF) production in Leydig tumor cell derived MA-10 cells. Both stimuli follow common signal transduction pathways including protein kinase A (PK-A), extracellular regulated kinase 1/2 (ERK1/2), and phosphatidyl inositol-3 kinase/akt (PI3-K/Akt) pathways in the stimulation of VEGF by MA-10 cells. In the present study we investigated the role of CoCl2 and 8-Br-cAMP on steroid production in MA-10 cells. The MA-10 cells were cultured in Waymouth MB 752/1 medium, supplemented with 15% heat inactivated horse serum. Progesterone was estimated by radioimmunoassay (RIA).We report that 8-Br-cAMP stimulated progesterone production by the MA-10 cells whereas CoCl2 inhibited the same. Also, 8-Br-cAMP stimulated steroidogenic acute regulatory protein (StAR) and cytochrome P450 side-chain cleavage enzyme (P450scc) mRNAs expression. However, CoCl2 had no effect on StAR mRNA. Cobalt chloride directly inhibited the expression of P450scc mRNA. The decrease in progesterone production could be attributed to three different mechanisms, (1) an increase in production of reactive oxygen species (ROS), (2) an increase in HIF-1α activity, and (3) ultimately a decrease in the level of cytochrome P450 side chain cleavage (CYT P450scc). Hypoxia has an action and mechanism of action similar to that of gonadotropins on VEGF production, whereas they have a contrasting effect on steroidogenesis. This study suggests that hypoxia could be as important as gonadotropins in regulating Leydig cell steroidogenesis.

Cordycepin stimulated steroidogenesis in MA-10 mouse Leydig tumor cells through the protein kinase C Pathway.

Cordycepin (3'-deoxyadenosine) is an adenosine analogue isolated from Cordyceps sinensis , which is a Chinese herbal medicine known to have many benefits, including adjustment of the physical condition, an anticancer effect, and enhancement of sexual performance. It was previously demonstrated that cordycepin could simultaneously activate steroidogenesis and apoptosis in MA-10 mouse Leydig tumor cells. However, the mechanism remains elusive. Thus, aim of the present study was to investigate the steroidogenic and apoptotic mechanism of cordycepin in MA-10 cells. MA-10 cells were treated with cordycepin at various dosages and time courses plus different protein kinase inhibitors. Steroid production, protein expression, and cell viability were then determined. Results illustrated that cordycepin stimulated MA-10 cell steroidogenesis in dose- and time-dependent relationships. However, cordycepin could not induce steroidogenic acute regulatory (StAR) protein expression. However, cordycepin did activate the phospholipase C/protein kinase C (PLC/PKC), but not PKA and PI3K, pathway to induce MA-10 cell steroidogenesis. Moreover, cordycepin could stimulate the phosphorylation of PKC, extracellular signal-regulated kinase 1/2 (ERK1/2), and c-Jun N-terminal kinase (c-JNK), but not p38, in MA-10 cells. In addition, cordycepin could activate the PKC pathway to induce MA-10 cell death, and this death effect was not caused by cordycepin-stimulated progesterone from MA-10 cells. In conclusion, cordycepin stimulated intracellular PLC/PKC and MAPK signal transduction pathways to induce steroidogenesis and cell death in MA-10 mouse Leydig tumor cells.

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

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.

Hypothalamic melanin-concentrating hormone and estrogen-induced weight loss.

Melanin-concentrating hormone (MCH) is an orexigenic neuropeptide produced by neurons of the lateral hypothalamic area (LHA). Because genetic MCH deficiency induces hypophagia and loss of body fat, we hypothesized that MCH neurons may represent a specific LHA pathway that, when inhibited, contributes to the pathogenesis of certain anorexia syndromes. To test this hypothesis, we measured behavioral, hormonal, and hypothalamic neuropeptide responses in two models of hyperestrogenemia in male rats, a highly reproducible anorexia paradigm. Whereas estrogen-induced weight loss engaged multiple systems that normally favor recovery of lost weight, the expected increase of MCH mRNA expression induced by energy restriction was selectively and completely abolished. These findings identify MCH neurons as specific targets of estrogen action and suggest that inhibition of these neurons may contribute to the hypophagic effect of estrogen.

Effects of extracted Cordyceps sinensis on steroidogenesis in MA-10 mouse Leydig tumor cells.

Extracts from the mycelium of Cordyceps sinensis (CS) were tested to determine the in vitro effect on Leydig cell function. MA-10 mouse Leydig tumor cells were used to conduct the experiments. Results showed that progesterone production gradually increased as the dosage of combined water and ethanol extracted CS increased, and there was a statistically significant difference in progesterone production stimulated by 20 mg/ml of CS extracts compared to the control. The combined water and ethanol extracted CS significantly stimulated MA-10 cell steroid production at 12 and 24 h of incubation. In addition, a protein synthesis inhibitor, cycloheximide, did not block the stimulatory effects of CS extracts on MA-10 cell steroid production or total protein expression. Moreover, the expression of steroidogenic acute regulatory (StAR) protein, which is a critical protein for steroidogenesis, stimulated by CS extracts, could not be detected by Western blot analysis. These data indicate that CS extracts might not induce StAR protein and/or other protein expressions to stimulate steroidogenesis in MA-10 mouse Leydig tumor cells.

Effects of methylcobalamin on the proliferation of androgen-sensitive or estrogen-sensitive malignant cells in culture and in vivo.

Methylcobalamin is one of the coenzymatically active cobalamin derivates and required for the activity of the cytoplasmic enzyme methionine synthetase catalyzing the methylation of homocysteine into methionine. The effect of methylcobalamin on the proliferation of malignant cells has been examined. Methylcobalamin inhibited the proliferation of androgen-sensitive SC-3 cells (a cloned cell line from Shionogi mouse mammary tumor, SC115) in culture at the concentration of 100-300 micrograms/ml. An inhibitory activity of methylcobalamin on the proliferation was also observed in other cell lines (estrogen-sensitive B-1F cells from mouse Leydig cell tumor and MCF-7 cells from human mammary tumor) at the concentration of 500 micrograms/ml. Moreover, large doses of methylcobalamin injected intraperitoneally (100 mg/kg body weight/day) were non-toxic and suppressed the tumor growth of SC115 and B-1F cells in mice fed a vitamin B12 deficient diet. These results show that methylcobalamin inhibits the proliferation of malignant cells in culture and in vivo and propose the possibility of methylcobalamin as a candidate of potentially useful agents for the treatment for some malignant tumors.

Regulatory role of arachidonic acid-derived metabolites for proliferation of transformed murine Leydig cell in serum-free culture condition.

The growth-regulatory ability of eicosanoids from arachidonic acid is poorly understood. To investigate their role in cell growth, we cultured transformed murine Leydig cells (B-1 or B-1 F) in serum-free medium supplemented with various compounds modulating arachidonic acid metabolism. The addition of 5-lipoxygenase inhibitors (AA 861, NDGA and quercetin) showed a growth-stimulative effect. On the other hand, their growth was remarkably inhibited by arachidonic acid added into the culture medium. This growth-inhibiting ability of arachidonic acid was almost completely reversed by a simultaneous exposure of B-1 cells to lipoxygenase inhibitor. Exogenously added 5-HETE inhibited cell proliferation in a dose-dependent manner. These results suggest that 5-lipoxygenase-catalyzed products from arachidonic acid have the ability to suppress the proliferation of some transformed cells.

Steroid production in vitro of a hilus cell tumor of the human ovary.

A 69-year-old heavily virilized woman with an androgen-producing tumor of the right ovary is described. After tumor removal, plasma testosterone levels fell from 5 to less than 0.6 ng/ml. Serum gonadotropins were low prior to surgery and rose to high levels postoperatively. Histologic examination of the right ovary revealed a hilus cell tumor. Incubation of small specimens of tumor tissue for 2 hours in oxygenated Krebs bicarbonate buffer containing glucose and bovine serum albumin yielded a release of predominantly testosterone and androstenedione into the medium. Human chorionic gonadotropin (hCG) added to the medium had no effect on steroid release. Incubation of tumor tissue in vitro may provide a useful functional adjuvant to the morphologic characterization of hormone-producing ovarian tumors. Such combined studies may increase our knowledge of the much-debated histogenesis of these tumors.

Hypercalcemia and neoplasia. Biologic, biochemical, and ultrastructural studies of a hypercalcemia-producing Leydig cell tumor of the rat.

A localized, transplantable testicular tumor of the Fischer rat regularly produces hypercalcemia and increased phosphorus clearance in host animals. Light and electron microscopic examinations of the tumor indicate that it is of Leydig origin. There is no evidence that the tumor secretes any biologically active sex steroids, judges by weights of target tissues, when the tumor is grown in castrated or spayed rats. No radioactive steroid hormone formation in vitro was detected using 1-14C-acetate as a precursor although 14C was incorporated into the "C27" sterol fraction. Mass (micrograms) amounts of sex steroids were not detected after purifying large amounts of tumor extracts. The phytosterols, beta-sitosterol, stigmasterol, campesterol, were tentatively identified in tumor extracts but were also found in other tissues and in tumors not associated with hypercalcemia. Administered in vivo, human chorionic gonadotropin caused an acute rise in serum calcium in 3 to 5 hours in tumor-bearing hypercalcemic rats. Only trophic hormones with luteinizing hormone activity were found to compete with 125I-human chorionic gonadotropin for binding to the tumor homogenate in vitro indicating the tumor possessed luteinizing hormone receptors. When the tumor was transplanted intrasplenically, hypercalcemia did not occur unless adhesions formed, suggesting that the tumor hormone was rapidly metabolized by the liver and was probably of small molecular weight. Secretory granules, usually thought to be associated with peptide hormone secretion, were not detected at the ultrastructure level. Cortisol, conjugated estrogen, and an inhibitor of sterol biosynthesis (AY-9944) were effective in lowering the elevated serum calcium. Definitive identification of the agent causing lethal hypercalcemia has not been accomplished. The available data suggest it is not parathyroid hormone or vitamin D. The Leydig cell origin of the tumor, its response to human chorionic gonadotropin in vivo, the lack of secretory granules at the ultrastructural level, and biologic characteristics, all lead to the speculation that the secretory product of the tumor is a new hormonal substance, possibly a steroid precursor or related substance not previously described or is a known substance of small molecular weight whose calcium-mobilizing properties have not been fully characterized. This transplantable tumor may represent a model for one form of neoplastic hypercalcemia occurring in man and may have important implications in the general area of calcium and phosphorus homeostasis.