Microarray Analysis Reveals Overexpression of both Integral Membrane and Cytosolic Tight Junction Genes in Endometrial Cancer Cell Lines.

Deregulation of tight junction (TJ) proteins and the associated disruption of TJ function has been demonstrated to play a role in the development of endometrial cancer. In the current study, we have shown overexpression of claudin-3 and -4 mRNA (by RT-PCR) and protein (by immunoblotting) in a panel of 9 human endometrial cancer cell lines. To further expand our understanding of the complex role of TJ deregulation in endometrial cancer, we also investigated the expression of 84 TJ and TJ-associated genes (encoding the array of proteins that function within the TJ network from the membrane to nuclear signaling pathways) by microarray analysis.

Comparison of transepithelial resistance measurement techniques: Chopsticks vs. Endohm.

Background: TER measurements across confluent cellular monolayers provide a useful indication of TJ strength between epithelial and endothelial cells in culture. Having a reliable and accurate method of measuring cell-to-cell adhesion is critical to studies in pathophysiology and cancer metastasis. However, the use of different technical approaches to measure TER has reportedly yielded inconsistent measurements within the same cell lines.

Doxycycline-Regulated p16 Expression Suppresses the Anchorage-Independence and Tumorigenicity of Breast Cancer Cell Lines that Lack Endogenous p16.

The RB pathway controls the critical transition from G1 into S phase of the mammalian cell cycle. Deregulation of the RB pathway by means of RB or p16 inactivation has been implicated in the development of virtually all human cancers. Such findings have led to the view that the loss of RB-mediated regulation at the G1/S checkpoint is a precondition for human malignancy.

Overexpression and delocalization of claudin-3 protein in MCF-7 and MDA-MB-415 breast cancer cell lines.

Tumor-specific deregulated expression of claudins, integral membrane proteins found in tight junctions (TJs), has indicated a possible role for TJ disruption in cancer progression. The current study demonstrates the marked overexpression of claudin-3 protein in two breast cancer cell lines of metastatic origin (MCF-7 and MDA-MB-415). Immunofluorescence and differential detergent fractionation analyses revealed that, although claudin-3 was primarily localized at cell junctions, it was also detected intracellularly.

Estrogen-dependent expression and subcellular localization of the tight junction protein claudin-4 in HEC-1A endometrial cancer cells.

Endometrial cancer is the most common female reproductive cancer in the United States and is associated with deregulated tight junction protein expression. Given the highly estrogen-responsive nature of this tissue, we investigated the effects of estrogen and its agonist, 4-OH TAM, on the expression and subcellular localization of the tight junction protein claudin-4 (CLDN-4), in HEC-1A endometrial cancer cells. In untreated HEC-1A cells, we observed dramatic overexpression of claudin-4 protein.

Small interference RNA-mediated suppression of overexpressed cyclin E protein restores G1/S regulation in NIH-OVCAR-3 ovarian cancer cells.

The development of ovarian cancer, unlike that of most human tumors, is rarely dependent upon the mutually exclusive loss of RB and p16 cell cycle proteins. RB+/p16+ ovarian cancer cell lines are, however, insensitive to the growth-suppressive effects of ectopically expressed p16 protein, which suggests that they harbor as yet unidentified defects that compromise cell cycle regulation in late G1/S. In the current study, we used Western blotting to analyze cyclin E protein expression in a panel of normal and tumor ovarian tissues and ovarian cancer cell lines (including the p16-insensitive RB+/p16+ ovarian cancer cell line, NIH-OVCAR-3).