SummaryAlthough age‐related ovarian failure in female mammals cannot be reversed, recent strategies have focused on improving reproductive capacity with age, and rapamycin is one such intervention that has shown a potential for preserving the ovarian follicle pool and preventing premature ovarian failure. However, the application is limited because of its detrimental effects on follicular development and ovulation during long‐term treatment. Herein, we shortened the rapamycin administration to 2 weeks and applied the protocol to both young (8 weeks) and middle‐aged (8 months) mouse models. Results showed disturbances in ovarian function during and shortly after treatment; however, all the treated animals returned to normal fertility 2 months later. Following natural mating, we observed prolongation of ovarian lifespan in both mouse models, with the most prominent effect occurring in mice older than 12 months. The effects of transient rapamycin treatment on ovarian lifespan were reflected in the preservation of primordial follicles, increases in oocyte quality, and improvement in the ovarian microenvironment. These data indicate that short‐term rapamycin treatment exhibits persistent effects on prolonging ovarian lifespan no matter the age at initiation of treatment. In order not to disturb fertility in young adults, investigators should in the future consider applying the protocol later in life so as to delay menopause in women, and at the same time increase ovarian lifespan.
Forkhead box M1 (FOXM1), a member of the Fox family of transcriptional factors, is considered to be an independent predictor of poor survival in many solid cancers. However, the underlying mechanism is not yet clear. The aim of the present study was to investigate the clinical significance of the correlation between FOXM1 and epithelial-mesenchymal transition (EMT) in non-small cell lung carcinoma and the possible mechanism responsible for FOXM1-induced EMT and metastasis. In the present study, expression levels of FOXM1 and EMT indicator proteins were determined by tissue microarray (TMA) and immunohistochemical staining, western blotting and reverse transcription-PCR (RT-PCR). Other cellular and molecular approaches including gene transfection, small interfering RNA (siRNA), and migration and invasion assays were utilized. Our results demonstrated that FOXM1 overexpression was statistically significantly associated with a higher TNM stage (p=0.036), lymph node metastasis (p=0.009) and a positive smoking history of the patients (p=0.044). Additionally, high expression of FOXM1 correlated with loss of E-cadherin expression (p<0.001) and anomalous immunopositivity of Vimentin (p=0.002). Moreover, patient survival analysis demonstrated that high expression of FOXM1 (p=0.043) and the presence of lymph node metastasis (p=0.042) were independent prognostic factors for non-small cell lung cancer (NSCLC). Furthermore, various in vitro experiments indicated that overexpression or knockdown of FOXM1 expression altered EMT through activation or inhibition of the AKT/p70S6K signaling pathway. Collectively, the results suggest that FOXM1 may be used as a prognostic indicator for patients with NSCLC and promotes metastasis by inducing EMT of lung cancer cells through activation of the AKT/p70S6K pathway. Therefore, we suggest that FOXM1 may be a potential target for lung cancer therapy.
In mammalian ovaries, follicle assembly requires proper germ cell cyst breakdown and the invasion of somatic cells to encapsulate individual oocytes. Abnormalities in this process lead to a number of pathologies such as premature ovarian failure and infertility. As a conserved pathway regulating cell growth and metabolism in response to growth factors and nutrients, the roles of mTOR signaling in follicular development have been extensively studied in recent years. However, its functions during follicle formation remain unknown. In this study, the expression of p-rpS6 (phospho-ribosomal proteinS6), a downstream marker of mTORC1, showed dynamic changes in perinatal ovaries. When E18.5 ovaries, which mainly contained germ cell nests, were incubated with the mTOR inhibitors Rapamycin and Torin1 for 24 h, follicle assembly was delayed with differential somatic cell invasion into germ cell cyst among the groups. After transplanting treated or untreated ovaries into kidney capsules of recipient ovariectomized mice, follicular development was blocked in treated ovaries, as shown by fewer antral follicles and a higher proportion of primordial follicles. Further studies showed a significant decrease in somatic cell proliferation and the expression of marker genes related to follicular development (Kitl, Kit, Gdf9, Bmp15, Zp3, and Amhr2) in treated ovaries. Moreover, the addition of KITL, a growth factor that is mainly produced by pregranulosa cells during germ cell nest breakdown, rescued the extension of follicle formation induced by mTOR inhibitors. These results suggest that KITL functions downstream of mTOR in somatic cells to regulate their communication with oocytes during follicle formation. J. Cell. Physiol. 232: 585-595, 2017. © 2016 Wiley Periodicals, Inc.
FOXM1, a member of the Forkhead transcriptional family, plays an important role in the EMT process, and transforming growth factor-β1 (TGF-β1) has been identified as the most potent factor that can independently induce EMT in various types of cancer cells. Here we examine the important role of FOXM1 in TGF-β1-induced EMT and investigate the mechanism underlying the relationship between TGF-β1 and FOXM1. Lentivirus-mediated transfection was used to stably upregulate the expression of FOXM1, and a small interfering RNA (siRNA) was introduced to silence the expression of FOXM1. Transwell and wound-healing assays were then performed to assess the invasion and motility potential of non-small cell lung cancer (NSCLC) cells. The NSCLC cell lines exhibited EMT characteristics, including an elongated fibroblastoid shape, induced expression of EMT marker proteins, and increased migratory and invasive potential after induction with TGF-β1. The overexpression of FOXM1 enhanced TGF-β1-induced EMT in NSCLC cells. Knockdown of FOXM1 reversed TGF-β1-induced EMT in NSCLC cell lines but had no effect on the phosphorylation level of ERK. Additionally, U0126, an ERK signaling inhibitor, exerted a reversible effect on TGF-β1-induced EMT and inhibited FOXM1 expression. FOXM1 regulated by the ERK pathway can mediate TGF-β1-induced EMT in NSCLC and is a potential target for the treatment of NSCLC.
In mammalian ovaries, primordial follicles remain in a quiescent state until activation by the surrounding microenvironment. Ovarian intervention, for example, ovarian cystectomy, ovarian wedge resection or laser drilling therapies for polycystic ovarian syndrome, has long been reported to change follicular development by an unknown mechanism(s). Herein, we established a murine model with partial ovarian resection of one ovary unilaterally, with the contralateral ovary undamaged. We found the injury accelerated follicular activation and development through the mTORC1 signaling pathway. Moreover, the stimulation of primordial follicles was restricted near the incision site where the mTORC1 pathway showed sequential activation beginning at the interstitial cells and proceeding to the primordial follicles. Total and polysome-associated RNA-seq revealed the increase of the nerve growth factor (NGF) family member, in both two fractions and immunostaining showed the restricted induction of NGF near the incision site. In cultured newborn ovaries, NGF demonstrated increase of follicular activation, and moreover, the NGF inhibitor K252a effectively blocked activation of primordial follicles stimulated by the surgery. We liken ovulation in mammals to minor tissue trauma, which happens naturally and cyclically in the body. As the increase in NGF accompanied the accumulation of activated primordial follicles after ovulation, our study may represent a common mechanism for selective follicular activation induced by a localized increase in NGF in interstitial cells and mediated via the mTOR signaling pathway. In addition, the NGF inhibitor K252a and the mTOR inhibitor rapamycin constitute good candidates for protecting follicular reserve against over exhaustion after ovarian surgery.
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