Humans ; Mechanistic Target of Rapamycin Complex 2/metabolism* ; Multiprotein Complexes/metabolism* ; Neural Stem Cells/metabolism* ; Proto-Oncogene Proteins c-akt/metabolism* ; Rapamycin-Insensitive Companion of mTOR Protein/metabolism* ; TOR Serine-Threonine Kinases/metabolism*

OBJECTIVETo explore the expression of Rictor and mTOR in the colorectal cancer and their clinical significance.

METHODSThe expression levels of Rictor and mTOR in HCT116, SW480, LoVo and HCoEpiC cells were detected by indirect immunofluorescence and Western blotting. Sixty-two paraffin-embedded surgical specimens of colorectal cancer tissue and adjacent tissues were examined for Rictor expression using immunohistochemistry. The association of the expression levels of Rictor protein with the clinicopathologic features and the overall survival of the patients was analyzed.

RESULTSThe expression level of Rictor was significantly higher in colorectal cancer tissues than in the adjacent tissues (P<0.05). The expression levels of Rictor and mTOR in the colon cancer cell lines were higher than those in human normal colon epithelial cell line HCoEpiC. The expression of Rictor was correlated with Dukes stage and lymphatic metastasis of the tumors but not with other clinicopathological parameter (P>0.05). Patients with Rictor expression had a lower overall survival rate than those without Rictor expression.

CONCLUSIONRictor overexpression is associated with the carcinogenesis and progression of colorectal cancer and can be an independent indicator for evaluating the prognosis of colorectal cancer patients.

Blotting, Western ; Carrier Proteins ; metabolism ; Cell Line, Tumor ; Colorectal Neoplasms ; metabolism ; Disease Progression ; Humans ; Immunohistochemistry ; Lymphatic Metastasis ; Prognosis ; Rapamycin-Insensitive Companion of mTOR Protein ; Survival Rate ; TOR Serine-Threonine Kinases ; metabolism

OBJECTIVE: To explore the expression, localization and regulatory effect on mitochondrial calcium signaling of Rictor in embryonic stem cell-derived cardiomyocytes (ESC-CMs). METHODS: Classical embryonic stem cell cardiomyogenesis model was used for differentiation of mouse embryonic stem cells into cardiomyocytes. The location of Rictor in ESC-CMs was investigated by immunofluorescence and Western blot. The expression of Rictor in mouse embryonic stem cells was interfered with lentiviral technology, then the superposition of mitochondria and endoplasmic reticulum (ER) in ESC-CMs was detected with immunofluorescence method; the cellular ultrastructure of ESC-CMs was observed by transmission electron microscope; the mitochondrial calcium transients of ESC-CMs was detected by living cell workstation;immunoprecipitation was used to detect the interaction between 1,5,5-trisphosphate receptor (IP3 receptor, IP3R), glucose-regulated protein 75 (Grp75) and voltage-dependent anion channel 1 (VDAC1) in mitochondrial outer membrane; the expression of mitochondrial fusion protein (mitonusin-2, Mfn2) was detected by Western blot. RESULTS: Rictor was mainly localized in the endoplasmic reticulum and mitochondrial-endoplasmic reticulum membrane (MAM) in ESC-CMs. Immunofluorescence results showed that Rictor was highly overlapped with ER and mitochondria in ESC-CMs. After mitochondrial and ER were labeled with Mito-Tracker Red and ER-Tracker Green, it was demonstrated that the mitochondria of the myocardial cells in the Rictor group were scattered, and the superimposition rate of mitochondria and ER was lower than that of the negative control group (<0.01). The MAM structures were decreased in ESC-CMs after knockdown of Rictor. The results of the living cell workstation showed that the amplitude of mitochondrial calcium transients by ATP stimulation in ESC-CMs was decreased after knockdown of Rictor (<0.01). The results of co-immunoprecipitation showed that the interaction between IP3R, Grp75 and VDAC1 in the MAM structure of the cardiomyocytes in the Rictor group was significantly attenuated (<0.01); the results of Western blot showed that the expression of Mfn2 protein was significantly decreased (<0.01). CONCLUSIONS Using lentiviral technology to interfere Rictor expression in mouse embryonic stem cells, the release of calcium from the endoplasmic reticulum to mitochondria in ESC-CMs decreases, which may be affected by reducing the interaction of IP3R, Grp75, VDAC1 and decreasing the expression of Mfn2, leading to the damage of MAM structure.
Animals ; Calcium Signaling ; genetics ; Gene Expression Regulation ; genetics ; Gene Knockdown Techniques ; Mice ; Mitochondria ; physiology ; Mouse Embryonic Stem Cells ; Myocytes, Cardiac ; physiology ; Protein Transport ; Rapamycin-Insensitive Companion of mTOR Protein ; genetics ; metabolism

OBJECTIVETo investigate the antiproliferation effect of cardamonin (CAR) and its possible mechanisms on human umbilical artery smooth muscle cells (HUASMCs) cultured in the mimicking insulin resistance (IR) medium.

METHODProliferation of HUASMCs was assayed by MTT method. The mRNA expression of mTOR, Raptor and Rictor was detected by a real-time PCR. The expression content was calculated by Livak method using internal control of beta-actin.

RESULTThe proliferation of HUASMCs cultured in the mimicking IR medium was significantly increased. Both in normal and mimic IR culture medium, cells proliferation was inhibited by CAR (1 x 10(-5), 1 x 10(-4) mol x L(-1)). Pretreated with PD98059 and LY294002, cell proliferation induced by phosphatidic acid (PA) was inhibited, and the mRNA expression of mTOR, Raptor and Rictor was significantly decreased by CAR in the mimic IR medium.

CONCLUSIONIt is implicated that antiproliferation of CAR is involved in mRNA expression decrease of mTOR and its relative protein Raptor and Rictor.

Adaptor Proteins, Signal Transducing ; genetics ; metabolism ; Carrier Proteins ; genetics ; metabolism ; Cell Proliferation ; drug effects ; Cells, Cultured ; Chalcones ; pharmacology ; Gene Expression Regulation ; drug effects ; Growth Inhibitors ; pharmacology ; Humans ; Myocytes, Smooth Muscle ; cytology ; drug effects ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Rapamycin-Insensitive Companion of mTOR Protein ; Regulatory-Associated Protein of mTOR ; TOR Serine-Threonine Kinases ; genetics ; metabolism

The Rictor/mTOR complex plays a pivotal role in a variety of cellular functions including cellular metabolism, cell proliferation and survival by phosphorylating Akt at Ser473 to fully activate the Akt kinase. However, its upstream regulatory pathways as well as whether it has additional function(s) remain largely unknown. We recently reported that Rictor contains a novel ubiquitin E3 ligase activity by forming a novel complex with Cullin-1, but not with other Cullin family members. Furthermore, we identified SGK1 as its downstream target. Interestingly, Rictor, but not Raptor or mTOR, promotes SGK1 ubiquitination. As a result, SGK1 expression is elevated in Rictor(-/-) MEFs. We further defined that as a feedback mechanism, Rictor can be phosphorylated by multiple AGC family kinases including Akt, S6K and SGK1. Phosphorylation of Rictor at the Thr1135 site did not affect its kinase activity towards phosphorylating its conventional substrates including Akt and SGK1. On the other hand, it disrupted the interaction between Rictor and Cullin-1. Consequently, T1135E Rictor was defective in promoting SGK1 ubiquitination and destruction. This finding further expands our knowledge of Rictor's function. Furthermore, our work also illustrates that Rictor E3 ligase activity could be governed by specific signaling kinase cascades, and that misregulation of this process might contribute to SGK overexpression which is frequently observed in various types of cancers.
Animals ; Carrier Proteins ; metabolism ; Cell Proliferation ; Cells, Cultured ; Cullin Proteins ; genetics ; metabolism ; Fibroblasts ; metabolism ; Humans ; Immediate-Early Proteins ; metabolism ; Mice ; Phosphorylation ; Protein-Serine-Threonine Kinases ; genetics ; metabolism ; Proto-Oncogene Proteins c-akt ; genetics ; metabolism ; Rapamycin-Insensitive Companion of mTOR Protein ; TOR Serine-Threonine Kinases ; genetics ; metabolism ; Ubiquitin ; genetics ; metabolism ; Ubiquitination

This study was aimed to analyze the expression profiles of PI3K/AKT signaling pathway genes from bone marrow samples of AML and ALL patients and normal samples. AML, ALL and normal bone marrow samples were collected from 6 AML, 6 ALL patients and 4 normal persons. The expression of PI3K/AKT signaling pathway genes including PTEN, CCND1, mTOR, RICTOR, FOXO1 were detected by real-time fluorescent quantification RT-PCR while GAPDH gene expression was used as an internal reference. The relative gene expression level was calculated by the method of the 2(-ΔΔCt). The results showed that the gene expression profiles were different between normal and leukemic groups. PTEN, mTOR and RICTOR expression levels were down-regulated, while FOXO1 and CCND1 levels were up-regulated in AML and ALL. PTEN was down-regulated in 10 out of the 12 samples; mTOR was down-regulated in 9 out of the 12 samples; RICTOR was down-regulated in 7 out of the 12 samples; FOXO1 was up-regulated in 9 out of the 12 samples and CCND1 was up-regulated in 7 out of the 12 samples. It is concluded that PI3K/AKT signal pathway is activated in both AML and ALL leukemic cells.
Carrier Proteins ; genetics ; metabolism ; Case-Control Studies ; Cyclin D1 ; genetics ; metabolism ; Forkhead Box Protein O1 ; Forkhead Transcription Factors ; genetics ; metabolism ; Gene Expression Regulation, Leukemic ; Humans ; Leukemia ; genetics ; metabolism ; PTEN Phosphohydrolase ; genetics ; metabolism ; Proto-Oncogene Proteins c-akt ; metabolism ; RNA, Messenger ; genetics ; Rapamycin-Insensitive Companion of mTOR Protein ; Signal Transduction ; TOR Serine-Threonine Kinases ; genetics ; metabolism ; Transcriptome