Matrine Activates PTEN to Induce Growth Inhibition and Apoptosis in V600EBRAF Harboring Melanoma Cells

Here, we report a natural chemical Matrine, which exhibits anti-melanoma potential with its PTEN activation mechanism. Matrine effectively inhibited proliferation of several carcinoma cell lines, including melanoma ^V600EBRAF harboring M21 cells. Flow cytometry analysis showed Matrine induced G₀/G₁ cell cycle arrest in M21 cells dose-dependently. Apoptosis in M21 cells induced by Matrine was identified by Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) analysis and Annexin-V/FITC staining. Molecular mechanistic study suggested that Matrine upregulated both mRNA level and protein expression level of phosphatase and tensin homolog deleted on chromosome ten (PTEN), leading to inhibition of the PI3K/Akt pathway. Downregulation of phosphor-Akt^ser473 by Matrine activated p21 and Bax, which contributed to G₀/G₁ cell cycle and apoptosis. Besides, Matrine enhanced the PI3K/Akt inhibition effects to inhibit the cell proliferation with PI3K inhibitor, LY2940002. In summary, our findings suggest Matrine is a promising antitumor drug candidate with its possible PTEN activation mechanisms for treating cancer diseases, such as melanomas.     

Downregulation of miR-17~92 Expression Increase Paclitaxel Sensitivity in Human Ovarian Carcinoma SKOV3-TR30 Cells via BIM Instead of PTEN

To better understand the molecular mechanisms of paclitaxel resistance in ovarian carcinoma, we evaluated the expression of miRNAs using miRNA microarray between human ovarian carcinoma SKOV3 cells and paclitaxel resistant SKOV3-TR30 cells. Results showed that 69 miRNAs were upregulated while 102 miRNAs were downregulated in SKOV3-TR30 cells. Using real-time PCR, we further clarified that miR-17~92 was overexpressed in SKOV3-TR30 cells compared with that in SKOV3 cells. We then established stable virally transduced SKOV3-TR30-m-PTIP-Sponge all SKOV3-TR30 cells and its vector-only control SKOV3-TR30-m-PTIP-GFP cells. Real time-PCR revealed that SKOV3-TR30-m-PTIP-Sponge all cells expressed approximately 6.18-fold lower levels of miR-17~92 compared with the control group. Decreased expression of miR-17~92 resulted in cell cycle arrest in the G2/M phase and growth inhibition. After the transduction, the BIM protein level was increased in SKOV3-TR30 cells and luciferase reporter assays revealed that miR-17~92 binds directly to the 3′-UTR of BIM. Results of luciferase reporter assays accompanied with Western Blot showed that although miR-17~92 binds directly to the 3′-UTR of PTEN, the PTEN protein expression level was upregulated slightly while the result is of no statistical significance. Our results showed that miR-17~92 could be a causal factor of the downregulation of BIM in SKOV3-TR30 cells and thus induce the paclitaxel resistance in SKOV3-TR30 cells.     

PTEN和LIVIN在弥漫大B细胞淋巴瘤组织中的表达及临床意义

目的: 探讨PTEN和LIVIN蛋白在弥漫大B细胞淋巴瘤组织中的表达及其临床意义。方法: 选取本院2008年7月至2011年5月初治的弥漫大B细胞淋巴瘤组织标本41例,反应性淋巴结增生21例作为对照组,采用免疫组化S-P法检测PTEN和LIVIN的表达,并探讨PTEN和LIVIN的表达与弥漫大B细胞淋巴瘤的分期及预后的关系。结果: PTEN在弥漫大B细胞淋巴瘤组织中表达率为 39.00%,对照组表达率为 80.95%(P<0.05);LIVIN在弥漫大B细胞淋巴瘤组织中表达率为 65.90％,对照组表达率为 23.81％(P<0.05)。弥漫大B细胞淋巴瘤组织切片PTEN与LIVIN表达存在显著的负相关。PTEN与患者性别、年龄、行为评分、Ann Arbor-Colswolds分期、结外受累、乳酸脱氢酶(LDH)高低、临床B组症状、IPI及病理类型无关。LIVIN表达与患者性别、年龄、Ann Arbor-Colswolds分期及是否有结外受累无关;与行为评分分组、LDH高低、临床是否伴有B组症状、IPI及病理类型有关。结论: PTEN在弥漫大B细胞淋巴瘤中低表达,与弥漫大B细胞淋巴瘤预后无相关性。LIVIN在弥漫大B细胞淋巴瘤中高表达,与患者行为评分分组、LDH高低、临床是否伴有B组症状、IPI及病理类型有关。LIVIN可作为判断弥漫大B细胞淋巴瘤预后的生物学指标。     

三叶青总黄酮逆转吉非替尼耐药肺腺癌细胞的耐药性

目的：探讨三叶青总黄酮（FTH）逆转吉非替尼（GEF）耐药肺腺癌细胞的耐药性及其初步机制。方法：采用MTT法,检测FTH对GEF耐药A549/GR细胞增殖的影响;采用流式细胞技术检测FTH对A549/GR细胞凋亡及周期的影响;建立A549/GR细胞荷瘤小鼠模型,观察两药联用后的体内抑瘤效果;采用Western blot法检测瘤组织PI3K/Akt信号通路关键蛋白（PTEN、PI3K、p-PI3K、AKT、p-AKT）的表达情况。结果：与单用GEF相比,FTH联合GEF给药可显著抑制A549/GR细胞增殖（P<0.05）,诱导A549/GR细胞凋亡（P<0.05）,使细胞停滞在G0/G1期。体内实验结果表明,两者联合可显著抑制裸鼠A549/GR移植瘤的生长（P<0.05）,并显著降低瘤组织p-PI3K和p-AKT表达（P<0.05）,升高PTEN蛋白表达（P<0.05）。 结论：FTH可逆转A549/GR细胞对GEF的耐药性,其作用机制可能与调控PTEN/PI3K/AKT通路有关。     

1,8-Cineole Ameliorates Steatosis of Pten Liver Specific KO Mice via Akt Inactivation

Hepatocyte-specific Phosphatase and tensin homolog (Pten)-knockout (KO) mice exhibit hepatic lesions analogous to non-alcoholic steatohepatitis (NASH). 1,8-cineole is a monoterpene oxide and it has several biological effects including hepatoprotective effects. In this study we revealed that 1,8-cineole ameliorates NASH of Pten KO mice. Pten KO mice were assigned to a control group without any medication or to a 1,8-cineole group injected with 50 mg/kg i.p. twice per week for eight weeks. At eight weeks, livers from each group were processed to measure triglyceride (TG) content, gene expression analysis, western blot analysis, and histological examination including Oil red O staining. 1,8-cineole ameliorated hepatic steatosis in Pten KO mice, revealed by TG content and Oil red O staining. Moreover, 1,8-cineole downregulated collagen 1a1 expression and improved liver fibrosis. Thus, 1,8-cineole has potential as a candidate to treat NASH by inactivating the Akt/PI3-kinase pathway.     

Exploiting the Metabolic Consequences of PTEN Loss and Akt/Hexokinase 2 Hyperactivation in Prostate Cancer: A New Role for δ-Tocotrienol

The Warburg effect is commonly recognized as a hallmark of nearly all tumors. In prostate cancer (PCa), it has been shown to be driven by PTEN loss- and Akt hyperactivation-associated upregulation of hexokinase 2 (HK2). δ-Tocotrienol (δ-TT) is an extensively studied antitumor compound; however, its role in affecting PCa glycolysis is still unclear. Herein, we demonstrated that δ-TT inhibits glucose uptake and lactate production in PTEN-deficient LNCaP and PC3 PCa cells, by specifically decreasing HK2 expression. Notably, this was accompanied by the inhibition of the Akt pathway. Moreover, the nutraceutical could synergize with the well-known hypoglycemic agent metformin in inducing PCa cell death, highlighting the crucial role of the above metabolic phenotype in δ-TT-mediated cytotoxicity. Collectively, these results unravel novel inhibitory effects of δ-TT on glycolytic reprogramming in PCa, thus providing new perspectives into the mechanisms of its antitumor activity and into its use in combination therapy.     

The Relationship and Expression of miR-451a,miR-25-3p and PTEN in Early Peritoneal Endometriotic Lesions and Their Modulation In Vitro

Background: miR-451a can function as a tumor suppresser and has been shown to be elevated in both endometriotic lesion tissue and serum from women with endometriosis. To further explore the role of miR-451a in the pathophysiology of endometriosis, specifically, further evaluating its association with the tumor suppressor, phosphatase and tensin homolog (PTEN), we examined their expression in individual endometriotic lesion tissue to gain insight into their relationship and further explore if miR-451a regulates PTEN expression. Methods: A total of 55 red, peritoneal endometriotic lesions and matched eutopic endometrial specimens were obtained from 46 patients with endometriosis. miR-451a, miR-25-3p and PTEN mRNA levels were assessed by qRT-PCR and reported for each matched eutopic and ectopic sample. To evaluate miR-451a and miR-25-3p expression of miR-25-3p and PTEN, respectively, 12Z cells (endometriotic epithelial cell line) were transfected and miR-25-3p expression was assessed by qRT-PCR, while PTEN protein expression was assessed by Western blotting. Results: PTEN and miR-25-3p expression exhibited an inverse relationship, as did miR-25-3p and miR-451a in individual lesions. Over-expression of miR-451a in 12Z cells resulted in down-regulation of miR-25-3p, while up-regulation of miR-25-3p resulted in down-regulation of PTEN protein expression. Conclusions: By assessing individual endometriotic lesion expression, we discovered an inverse relationship between miR-451a, miR-25-3p and PTEN, while in vitro cell transfection studies suggest that miR-451a may regulate PTEN expression via modulating miR-25-3p.     

Phospholipid Scramblase 4 (PLSCR4) Regulates Adipocyte Differentiation via PIP3-Mediated AKT Activation

Phospholipid scramblase 4 (PLSCR4) is a member of a conserved enzyme family with high relevance for the remodeling of phospholipid distribution in the plasma membrane and the regulation of cellular signaling. While PLSCR1 and -3 are involved in the regulation of adipose-tissue expansion, the role of PLSCR4 is so far unknown. PLSCR4 is significantly downregulated in an adipose-progenitor-cell model of deficiency for phosphatase and tensin homolog (PTEN). PTEN acts as a tumor suppressor and antagonist of the growth and survival signaling phosphoinositide 3-kinase (PI3K)/AKT cascade by dephosphorylating phosphatidylinositol-3,4,5-trisphosphate (PIP3). Patients with PTEN germline deletion frequently develop lipomas. The underlying mechanism for this aberrant adipose-tissue growth is incompletely understood. PLSCR4 is most highly expressed in human adipose tissue, compared with other phospholipid scramblases, suggesting a specific role of PLSCR4 in adipose-tissue biology. In cell and mouse models of lipid accumulation, we found PLSCR4 to be downregulated. We observed increased adipogenesis in PLSCR4-knockdown adipose progenitor cells, while PLSCR4 overexpression attenuated lipid accumulation. PLSCR4 knockdown was associated with increased PIP3 levels and the activation of AKT. Our results indicated that PLSCR4 is a regulator of PI3K/AKT signaling and adipogenesis and may play a role in PTEN-associated adipose-tissue overgrowth and lipoma formation.