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PTEN and rapamycin inhibiting the growth of K562 cells through regulating mTOR signaling pathway.

ABSTRACT: To investigate, in vitro, the regulatory effects of tumor-suppressing gene PTEN on mTOR (mammalian target of rapamycin) signaling pathway, the effects of transfected PTEN and rapamycin on the growth inhibition, and apoptosis induction for human leukemia cell line K562 cells.K562 cells were transfected with recombined adenovirus-PTEN vector containing green fluorescent protein (Ad-PTEN-GFP), followed by the treatment of the cells with or without rapamycin. The proliferation inhibition rate and apoptotic rate of these transfected and/or rapamycin treated K562 cells were measured by MTT assay and flow cytometry (FCM), the expression levels of PTEN-, mTOR-, cyclinD1- and P27kip1- mRNA were measured by real-time fluorescent relative-quantification reverse transcriptional PCR (FQ-PCR), the protein expression levels of PTEN, Akt, p-Akt were detected by western blotting.The proliferation of K562 cells was inhibited by PTEN gene transfection with/without the treatment of rapamycin. The expression levels of PTEN- and P27kip1- mRNA were up-regulated, and the mTOR- and cyclinD1- mRNA were down-regulated in K562 cells after the cells transfected with wild type PTEN gene and treated with rapamycin.PTEN and rapamycin inhibited mTOR expression by acting as an upstream regulator of mTOR. Low dose rapamycin in combination with over-expressed PTEN might have synergistic effects on inhibiting the proliferation and promoting apoptosis of K562 cells.

SUBMITTER: Cheng ZY

PROVIDER: S-EPMC2639541 | biostudies-literature | 2008 Dec

REPOSITORIES: biostudies-literature

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PTEN and rapamycin inhibiting the growth of K562 cells through regulating mTOR signaling pathway.

Cheng Zhi Y ZY Guo Xiao L XL Yang Xiao Y XY Niu Zhi Y ZY Li Shi H SH Wang Su Y SY Chen Hao H Pan Ling L

Journal of experimental & clinical cancer research : CR 20081230

<h4>Objective</h4>To investigate, in vitro, the regulatory effects of tumor-suppressing gene PTEN on mTOR (mammalian target of rapamycin) signaling pathway, the effects of transfected PTEN and rapamycin on the growth inhibition, and apoptosis induction for human leukemia cell line K562 cells.<h4>Methods</h4>K562 cells were transfected with recombined adenovirus-PTEN vector containing green fluorescent protein (Ad-PTEN-GFP), followed by the treatment of the cells with or without rapamycin. The pr ...[more]

PMID: 19115995

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Project description:Primordial follicular depletion has thought to be a common adverse effect of chemotherapy especially for female of reproductive age. The study aimed to evaluate the protective effect of rapamycin on the primordial follicles and its potential mechanism for patients receiving chemotherapy.8-week old BALB/c female mice were randomly assigned into four groups (control; rapamycin; cyclophosphamide; and rapamycin combined with cyclophosphamide). Hematoxylin staining, immunohistochemical, TUNEL, western blotting and ELISA were employed to assess inter-group differences using Student's t-test and Mann-Whitney test.Cyclophosphamide depleted the follicular reserve and induced the phosphorylation of the key proteins of PI3K/Akt/mTOR pathway in mice in a dose-dependent manner. Co-treatment with rapamycin significantly reduced primordial follicle loss at all cyclophosphamide dose groups and prevent the follicle growth wave caused by cyclophosphamide treatment (P < 0.05). TUNEL staining showed that no apoptosis occured in the primordial follicles in all groups and fewer apoptosis in large growing follicles were observed in ovaries from rapamycin + cyclophosphamide group compared to that received cyclophosphamide alone. Serum anti-Müllerian hormone (AMH) was significantly reduced in cyclophosphamide alone group, in contrast to the normal level in rapamycin + cyclophosphamide group. Compared to p-Akt/Akt and p-mtor/mtor, p-rps6/rps6 was significantly decreased in rapamycin + cyclophosphamide group (P < 0.05), indicating that rapamycin attenuated the increased level of phosphorylation of rpS6 after cyclophosphamide treatment.Rapamycin can prevent the primordial follicle activation induced by cyclophosphamide through PI3K/Akt/mTOR signaling pathway and thus plays a role in preserving the follicle pool. These results suggest that rapamycin may be an effective protection for ovarian function during chemotherapy, which means a new nonsurgical application for protection of ovarian reserve and prevention of POF.

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PTEN and rapamycin inhibiting the growth of K562 cells through regulating mTOR signaling pathway.

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PTEN and rapamycin inhibiting the growth of K562 cells through regulating mTOR signaling pathway.

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