H19/miR-675 non-coding RNA expression differentiates among cancers of the human endometrium.

H19 is a maternally expressed non-coding RNA located at chromosome 11p15.5 near the reciprocally imprinted insulin-like growth factor 2 (IGF2) gene. Though the function of H19 is unknown, it is transcribed during embryonic development after which transcription is absent in all but a few tissues including cardiac muscle, breast, ovary, uterus, and placenta. Linking H19, miR-675 and RB1 expression with serous tumors of the endometrium suggests that RB1 suppression may be a differentiating event in serous tumorigenesis

BKCa channel inhibitor modulates the tumorigenic ability of hormone-independent breast cancer cells via the Wnt pathway

In breast cancers, the large conductance Ca(2+) and voltage sensitive K(+) (BKCa) channels have been hypothesized to function as oncoproteins, yet it remains unclear how inhibition of channel activity impacts oncogenesis. We demonstrated herein that iberiotoxin (IbTX), an inhibitor of BKCa channels, differentially modulated the in vitro tumorigenic activities of hormone-independent breast cancer cells. Specifically, in HER-2/neu-overexpressing UACC893 cells and triple-negative MDA-MB-231 cells, IbTX selectively attenuated anchorage-independent growth with concomitant downregulation of β-catenin as well as total and phosphorylated Akt and HER-2/neu. By contrast, HER-2/neu-overexpressing SK-BR-3 cells were insensitive to IbTX. Molecular analyses showed an absence of β-catenin and a dose-dependent upregulation of total and phosphorylated Akt and HER-2/neu in these cells. Taken together, these studies identify β-catenin as a putative modulator of the inhibitory actions of IbTX in sensitive breast cancer cells

Role of MTDH, FOXM1 and microRNAs in Drug Resistance in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most lethal malignancies due to underlying co-morbid cirrhosis and chemo-resistance. Vaccination and improved treatment for hepatitis are the most effective means to reduce the burden of liver cancer worldwide. Expression of biomarkers such as AFP (alpha-fetoprotein), DDK1 (Dickkopf WNT Signaling Pathway Inhibitor 1) and microRNAs in blood are being tested for early screening of liver cancer. Since 2008, sorafenib has been used as the standard molecular targeting agent for HCC. However, overall outcomes for sorafenib alone or in combination with other tyrosine kinase inhibitors are unsatisfactory. Whether simultaneously or sequentially, addiction switches and compensatory pathway activation in HCC, induced by sorafenib treatment, may induce acquired resistance. Forkhead box M1 (FOXM1) and metadherin (MTDH) have been shown to be master regulators of different aspects of tumorigenesis, including angiogenesis, invasion, metastasis and drug resistance. Elevated expression of both FOXM1 and MTDH is known to be a consequence of both activating mutations in oncogenes such as PI3K, Ras, myc and loss of function mutations in tumor suppressor genes such as p53 and PTEN in various types of cancers including HCC. The role of FOXM1 and MTDH as potential prognostic markers as well as therapeutic targets in HCC will be discussed. In addition, microRNAs (miRNAs), endogenous small non-coding RNAs involved in the regulation of gene expression, are involved in HCC and interact with both FOXM1 and MTDH in several ways. Thus, altered expression of miRNAs in HCCs will also be discussed as potential tools for diagnosis, prognosis and therapy in HCC

The Synthetic Curcumin Analog HO-3867 Rescues Suppression of PLAC1 Expression in Ovarian Cancer Cells

Elevated expression of placenta-specific protein 1 (PLAC1) is associated with the increased proliferation and invasiveness of a variety of human cancers, including ovarian cancer. Recent studies have shown that the tumor suppressor p53 directly suppresses PLAC1 transcription. However, mutations in p53 lead to the loss of PLAC1 transcriptional suppression. Small molecules that structurally convert mutant p53 proteins to wild-type conformations are emerging. Our objective was to determine whether the restoration of the wild-type function of mutated p53 could rescue PLAC1 transcriptional suppression in tumors harboring certain TP53 mutations. Ovarian cancer cells OVCAR3 and ES-2, both harboring TP53 missense mutations, were treated with the p53 reactivator HO-3867. Treatment with HO-3867 successfully rescued PLAC1 transcriptional suppression. In addition, cell proliferation was inhibited and cell death through apoptosis was increased in both cell lines. We conclude that the use of HO-3867 as an adjuvant to conventional therapeutics in ovarian cancers harboring TP53 missense mutations could improve patient outcomes. Validation of this conclusion must, however, come from an appropriately designed clinical trial

Redox activation of Nox1 (NADPH Oxidase 1) involves an intermolecular disulfide bond between protein disulfide isomerase and p47phox in vascular smooth muscle cells

Objective— PDI (protein disulfide isomerase A1) was reported to support Nox1 (NADPH oxidase) activation mediated by growth factors in vascular smooth muscle cells. Our aim was to investigate the molecular mechanism by which PDI activates Nox1 and the functional implications of PDI in Nox1 activation in vascular disease. Approach and Results— Using recombinant proteins, we identified a redox interaction between PDI and the cytosolic subunit p47phox in vitro. Mass spectrometry of crosslinked peptides confirmed redox-dependent disulfide bonds between cysteines of p47phox and PDI and an intramolecular bond between Cys 196 and 378 in p47phox. PDI catalytic Cys 400 and p47phox Cys 196 were essential for the activation of Nox1 by PDI in vascular smooth muscle cells. Transfection of PDI resulted in the rapid oxidation of a redox-sensitive protein linked to p47phox, whereas PDI mutant did not promote this effect. Mutation of p47phox Cys 196, or the redox active cysteines of PDI, prevented Nox1 complex assembly and vascular smooth muscle cell migration. Proximity ligation assay confirmed the interaction of PDI and p47phox in murine carotid arteries after wire injury. Moreover, in human atheroma plaques, a positive correlation between the expression of PDI and p47phox occurred only in PDI family members with the a′ redox active site. Conclusions— PDI redox cysteines facilitate Nox1 complex assembly, thus identifying a new mechanism through which PDI regulates Nox activity in vascular diseas