Anti-AKT (phospho-T308) Antibody (A24862)

Tectorigenin is a plant isoflavonoid originally isolated from the dried flower of Pueraria thomsonii Benth. Although its anti-inflammatory and anti-hyperglycosemia effects have been well documented, the effect of tectorigenin on endothelial dysfunction insulin resistance involved has not yet been reported. Herein, this study aims to investigate the action of tectorigenin on amelioration of insulin resistance in the endothelium. Palmitic acid (PA) was chosen as a stimulant to induce ROS production in endothelial cells and successfully established insulin resistance evidenced by the specific impairment of insulin PI3K signaling. Tectorigenin effectively inhibited the ability of PA to induce the production of reactive oxygen species and collapse of mitochondrial membrane potential. Moreover, tectorigenin presented strong inhibition effect on ROS-associated inflammation, as TNF-α and IL-6 production in endothelial cells was greatly reduced with suppression of IKKβ/NF-κB phosphorylation and JNK activation. Tectorigenin also can inhibit inflammation-stimulated IRS-1 serine phosphorylation and restore the impaired insulin PI3K signaling, leading to a decreased NO production. These results demonstrated its positive regulation of insulin action in the endothelium. Meanwhile, tectorigenin down-regulated endothelin-1 and vascular cell adhesion molecule-1 overexpression, and restored the loss of insulin-mediated vasodilation in rat aorta. These findings suggested that tectorigenin could inhibit ROS-associated inflammation and ameliorated endothelial dysfunction implicated in insulin resistance through regulating IRS-1 function. Tectorigenin might have potential to be applied for the management of cardiovascular diseases involved in diabetes and insulin resistance.

BACKGROUND:

Alterations in the phosphoinositide 3-kinase/AKT/mammalian target of rapamycin (PI3K/AKT/mTOR) signalling pathway are frequent in urothelial bladder cancer (BLCA) and thus provide a potential target for novel therapeutic strategies. We investigated the efficacy of the AKT inhibitor MK-2206 in BLCA and the molecular determinants that predict therapy response.

METHODS:

Biochemical and functional effects of the AKT inhibitor MK-2206 were analysed on a panel of 11 BLCA cell lines possessing different genetic alterations. Cell viability (CellTiter-Blue, cell counts), apoptosis (caspase 3/7 activity) and cell cycle progression (EdU incorporation) were analysed to determine effects on cell growth and proliferation. cDNA or siRNA transfections were used to manipulate the expression of specific proteins such as wild-type or mutant PIK3CA, DUSP1 or CREB. For in vivo analysis, the chicken chorioallantoic membrane model was utilised and tumours were characterised by weight and biochemically for the expression of Ki-67 and AKT phosphorylation.

RESULTS:

Treatment with MK-2206 suppressed AKT and S6K1 but not 4E-BP1 phosphorylation in all cell lines. Functionally, only cell lines bearing mutations in the hotspot helical domain of PIK3CA were sensitive to the drug, independent of other genetic alterations in the PI3K or MAPK signalling pathway. Following MK-2206 treatment, the presence of mutant PIK3CA resulted in an increase in DUSP1 expression that induced a decrease in ERK 1/2 phosphorylation. Manipulating the expression of mutant or wild-type PIK3CA or DUSP1 confirmed that this mechanism is responsible for the induction of apoptosis and the inhibition of tumour proliferation in vitro and in vivo, to sensitise cells to AKT target therapy.Conclusion or interpretation:PIK3CA mutations confer sensitivity to AKT target therapy in BLCA by regulating DUSP1 expression and subsequent ERK1/2 dephosphorylation and can potentially serve as a stratifying biomarker for treatment.

Transarterial chemoembolization represents a first-line non-curative therapy for hepatocellular carcinoma (HCC), although the biological changes in the remaining cancer after embolization are not completely understood. In the present study, we examined whether transarterial embolization (TAE) enhances the metastatic potential of residual HCC and investigated the mechanisms underlying embolization. The hepatoma cell line McA-RH7777, which is marked by green fluorescent protein (GFP), was used in the study. The invasion of cells cultured under hypoxia and normoxia was observed using the Transwell assay. Twenty male buffalo rats were implanted with GFP transfected McA-RH7777 tumors in the left lateral lobe of the liver. After laparotomy and retrograde placement of a catheter into the gastroduodenal artery (on the 14th day after implantation), TAE using lipiodol (0.2 ml/kg) was performed. Tumor volumes were measured before and after treatment using magnetic resonance imaging (MRI). Lung metastases were observed using fluorescence imaging, and the molecular changes of residual tumor cells were evaluated by western blotting or immunohistochemistry. The invasion assays indicated that the number of invading hypoxic cells was significantly higher than that of normoxic cells (30.2 ± 2.46 vs. 20.4 ± 1.89, P=0.013). Accompanying an increase in hypoxia-inducible factor-1α (HIF-1α) expression, the metastatic potential of tumor cells following hypoxia or TAE was enhanced. This enhanced metastatic potential was indicated by a significant reduction in the expression of E-cadherin and an upregulation of N-cadherin and vimentin expression. The number of lung metastases in the TAE group was 19.20 ± 1.76, whereas this number was 11.30 ± 1.54 in the control group, which represented a statistically significant difference (P=0.003). In conclusion, hypoxia in the residual tumor after TAE can increase the invasiveness and metastatic potential of HCC and may be responsible for the failure of TAE.

Progressive death of retinal ganglion cells (RGCs) is a major cause of irreversible visual impairment after optic nerve injury. Clinically, there are still no effective treatments for recovering the visual function at present. The probable approaches to maintain the vision and RGCs function involve in preventing RGCs from death and/or promoting the regeneration of damaged RGCs. Previous studies have shown that mesenchymal stem cells (MSCs) take neuroprotective effects on ischemia-induced cortical and spinal cord injury, however, whether MSCs have a beneficial effect on the optical nerve injury is not clearly determined. In present study, we transplanted MSCs derived from human umbilical cord blood (hUCB-MSCs) into the vitreous cavity of adult rats and investigated the probable capacity of anti-apoptosis and pro-neuroprotective effects on RGCs. RGCs were retrogradely traced by fluorescent gold particles (FG); cellular apoptosis was investigated by caspase-3 immunohistochemistry and terminal dUTP nick end labeling (TUNEL) staining. Hematoxylin-eosin (HE) staining was used to observe the morphological changes of the retina. Growth associated protein 43 (GAP-43), an established marker for axonal regeneration, was used to visualize the regenerative process over time. Expression of P2X7 receptors (P2X7R), which are responsible for inflammatory and immune responses, was also monitored in our experiments. We found that the hUCB-MSC transplantation significantly decreased cellular apoptosis and promoted the survival of RGCs in early phase. However, this protection was transient and the RGCs could not be protected from death in the end. Consistent with apoptosis detection, P2X7R was also significantly decreased in hUCB-MSC transplanted rats in the early time but without obvious difference to the rats from control group in the end. Thus, our results imply that hUCB-MSCs take anti-apoptotic, pro-neuroregenerative and anti-inflammatory effects in the early time for acute optic nerve injury in adult rats but could not prevent RGCs from death eventually.

Pancreatic cancer remains the fourth most common cause of cancer-related death in the United States. Potent therapeutic strategies are urgently needed for pancreatic cancer. Cucurmosin is a novel type 1 ribosome-inactivating protein (RIP) isolated from the sarcocarp of Cucurbita moschata (pumpkin). Due to its cytotoxicity, cucurmosin can inhibit tumor cell proliferation through induction of apoptosis on tumor cells, but the specific mechanism is still unclear. We explored the function of cucurmosin in BxPC-3 pancreatic cancer cells using multiple cellular and molecular approaches such as 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, flow cytometry, reverse transcription polymerase chain reaction (RT-PCR), Western blotting and transmission electron microscopy for observing typical changes and formation of apoptotic bodies. We found that cucurmosin inhibited the proliferation of BxPC-3 cells in a time- and dose-dependent manner, and increased the cell population in the G0-G1 phase. With increasing concentration of cucurmosin, the expression of EGFR, p-PI3K, Akt, p-Akt, mTOR, p-mTOR, P70S6K-α, p-P70S6K-α, 4E-BP1 and p-4E-BP1 at the protein level was decreased, whereas the expression of p-Bad and caspase-9 was elevated. However, the mRNA expression of EGFR did not change. These findings suggest that cucurmosin can down-regulate the expression of EGFR by targeting. Cucurmosin induces the apoptosis of BxPC-3 pancreatic cancer cells via the PI3K/Akt/mTOR signaling pathway.