Acute physical exercise increases PI3K-p110α protein content in the hypothalamus of obese mice

The anatomy of the hypothalamus includes many nuclei and a complex network of neurocircuits. In this context, some hypothalamic nuclei reside closer to the blood-brain barrier, allowing communication with the peripheral organs through some molecules, such as leptin. Leptin is considered the main adipokine for energy homeostasis control. Furthermore, leptin signalling in the hypothalamus can communicate with insulin signalling through the activation of phosphoinositide 3-kinase (PI3k). Previous data suggest that isoforms of PI3k are necessary to mediate insulin action in the hypothalamus. However, obese animals show impairment in the central signalling of these hormones. Thus, in the current study, we evaluated the role of acute exercise in the leptin and insulin pathways in the hypothalamus, as well as in food intake control in obese mice. Although acute physical exercise was not able to modulate leptin signalling, this protocol suppressed the increase in the suppressor of cytokine signalling 3 (SOCS3) protein levels. In addition, acute exercise increased the content of PI3k-p110α protein in the hypothalamus. The exercised animals showed a strong tendency to reduction in cumulative food intake. For the first time, our results indicate physical exercise can increase PI3k-p110α protein content in the hypothalamus of obese mice and regulate food intake.

The exosome-mediated PI3k/Akt/mTOR signaling pathway in cervical cancer

BACKGROUND

Cervical cancer is the second most common cancer and one of the leading causes of cancer deaths among women worldwide.

OBJECTIVE

To evaluate the clinical significance of the PI3k/Akt/mTOR signaling pathway in cancer tissues and exosomes extracted from vaginal secretions.

METHODS

Immunohistochemical staining was used to detect the protein expression of PI3k, Akt, and mTOR in tissue samples from the control group, the CIN (cervical intraepithelial neoplasia) group, and the cervical cancer group. qPCR (quantitative PCR) was used to detect the expressions of PI3k, Akt, and mTOR in cervical cancer tissues, the corresponding adjacent tissues, and exosomes extracted from vaginal secretions.

RESULTS

Compared with those of healthy people and CIN, the PI3k/Akt/mTOR protein levels in extracts from tissues were higher in the cervical cancer patients. The PI3k/Akt/mTOR gene and protein levels increased in the cervical cancer tissues with the increase in the degree of malignancy of the cancer. There was no significant difference in PI3k/Akt/mTOR gene expression between the cervical cancer tissues and the exosomes extracted from vaginal secretions, but both were significantly higher than the expressions of the corresponding adjacent tissues.

CONCLUSIONS

The PI3k/Akt/mTOR signaling pathway mediated by exosomes extracted from vaginal secretions may provide candidate diagnostic biomarkers or potential therapeutic targets.

IL-8 Enhances Therapeutic Effects of BMSCs on Bone Regeneration via CXCR2-Mediated PI3k/Akt Signaling Pathway

BACKGROUND/AIMS

Tissue engineering bone transplantation with bone marrow mesenchymal stem cells (BMSCs) is an effective technology to treat massive bone loss, while molecular regulation of the bone regeneration processes remains poorly understood. Here, we aimed to assess the role of interleukin-8 (IL-8) in the recruitment of host cells by seeded BMSCs and in the bone regeneration.

METHODS

A transwell assay was performed to examine the role of IL-8/CXCR1/CXCR2/PI3k/Akt on the migration potential of hBMSCs. The in vitro chondrogenic differentiation of hBMSCs was assessed by examination of 2 chondrogenic markers, Sox9 and type 2 collagen (COL2). mBMSCs were used in tissue engineered bone (TEB) with/without IL-8 implanted into bone defect area with CXCR2 or Akt inhibitors. Density and Masson staining of the regenerated bone were assessed. The chondrogenesis was assessed by expression levels of associated proteins, Sox9 and COL2, by RT-qPCR and by immunohistochemistry.

RESULTS

IL-8 may trigger in vitro migration of hBMSCs via CXCR2-mediated PI3k/Akt signaling pathway. IL-8 enhances osteogenesis in the TEB-implanted bone defect in mice. IL-8 induces chondrogenic differentiation of hBMSCs via CXCR2-mediated PI3k/Akt signaling pathway in vitro and in vivo.

CONCLUSIONS

IL-8 enhances therapeutic effects of MSCs on bone regeneration via CXCR2-mediated PI3k/Akt signaling pathway.

"Immune TOR-opathies," a Novel Disease Entity in Clinical Immunology

Primary immunodeficiencies (PIDs) represent a group of mostly monogenic disorders caused by loss- or gain-of-function mutations in over 340 known genes that lead to abnormalities in the development and/or the function of the immune system. However, mutations in different genes can affect the same cell-signaling pathway and result in overlapping clinical phenotypes. In particular, mutations in the genes encoding for members of the phosphoinositide3-kinase (PI3K)/AKT/mTOR/S6 kinase (S6K) signaling cascade or for molecules interacting with this pathway have been associated with different PIDs that are often characterized by the coexistence of both immune deficiency and autoimmunity. The serine/threonine kinase mechanistic/mammalian target of rapamycin (mTOR), which acts downstream of PI3K and AKT, is emerging as a key regulator of immune responses. It integrates a variety of signals from the microenvironment to control cell growth, proliferation, and metabolism. mTOR plays therefore a central role in the regulation of immune cells’ differentiation and functions. Here, we review the different PIDs that share an impairment of the PI3K/AKT/mTOR/S6K pathway and we propose to name them “immune TOR-opathies” by analogy with a group of neurological disorders that has been originally defined by PB Crino and that are due to aberrant mTOR signaling (1). A better understanding of the role played by this complex intracellular cascade in the pathophysiology of “immune TOR-opathies” is crucial to develop targeted therapies.

Ginsenoside Rh2 inhibits metastasis of glioblastoma multiforme through Akt-regulated MMP13

Glioblastoma multiforme (GBM) is the most malignant type of primary brain tumor. Although the growth of the tumor cells in a relatively closed space may partially account for its malignancy, highly invasive nature of glioblastoma cells has been suggested to be the main reason for the failure of current therapeutic approaches. Ginsenoside Rh2 (GRh2) has recently been shown to significantly suppress the growth and survival of GBM through inhibiting epidermal growth factor receptor signaling, whereas its effects on the invasion and metastasis have not been examined. Here, we showed that GRh2 dose-dependently decreased GBM cell invasiveness in both scratch wound healing assay and Transwell cell migration assay. Moreover, the inhibitory effects of GRh2 on cell migration seemed to be conducted through decreased expression of matrix metalloproteinase (MMP)-13. Furthermore, using specific inhibitors, we found that GRh2 inhibited MMP13 through PI3k/Akt signaling pathway. Finally, high MMP13 levels were detected in GBM specimen from the patients. Together, these data suggest that GRh2 may suppress GBM migration through inhibiting Akt-mediated MMP13 activation. Thus, our data highlight a previous unappreciated role for GRh2 in suppressing GBM cell metastasis.

Cell cycle arrest or survival signaling through αv integrins, activation of PKC and ERK1/2 lead to anoikis resistance of ovarian cancer spheroids

Ovarian cancer is the most lethal gynecologic cancer mainly due to spheroids organization of cancer cells that disseminate within the peritoneal cavity. We have investigated the molecular mechanisms by which ovarian cancer spheroids resist anoikis, choosing as models the 2 well-characterized human ovarian cancer cell lines IGROV1 and SKOV3. These cell lines have the propensity to float as clusters, and were isolated from tumor tissue and ascites, respectively. To form spheroids, IGROV1 and SKOV3 ovarian adenocarcinoma cells were maintained under anchorage-independent culture conditions, in which both lines survive at least a week. A short apoptotic period prior to a survival signaling commitment was observed for IGROV1 cells whereas SKOV3 cells entered G0/G1 phase of the cell cycle. This difference in behavior was due to different signals. With regard to SKOV3 cells, activation of p38 and an increase in p130/Rb occurred once anchorage-independent culture was established. Analyses of the survival signaling pathway switched on by IGROV1 cells showed that activation of ERK1/2 was required to evade apoptosis, an effect partly dependent on PKC activation and αv integrins. αv-integrin expression is essential for survival through activation of ERK1/2 phosphorylation. The above data indicate that ovarian cancer cells can resist anoikis in the spheroid state by arrest in the cell cycle or through activation of αv-integrin-ERK-mediated survival signals. Such signaling might result in the selection of resistant cells within disseminating spheroids, favoring further relapse in ovarian cancers.