BACKGROUND Guibi-tang (GBT), a traditional herbal formula, mainly has been shown to possess immune regulation, antioxidant and protective effect of the gastric mucosa. Constituent herbs of GBT are frequently used to treat various diseases; however, their pharmacological effects, especially on cancer cells, differ from those of GBT. Furthermore, the molecular mechanisms behind effects of GBT rem...

The roles of protein-tyrosine phosphatases (PTPs) in processes such as cell growth and adhesion are poorly understood. To explore the ability of specific PTPs to regulate cell signaling pathways initiated by stimulation of growth factor receptors, we expressed the receptor-like PTP, PTPalpha, in A431 epidermoid carcinoma cells. These cells express high levels of the epidermal growth factor (EGF...

PURPOSE The role of phosphatidylcholine-specific phospholipase C (PC-PLC), the enzyme involved in cell differentiation and proliferation, has not yet been explored in tumor initiating cells (TICs). We investigated PC-PLC expression and effects of PC-PLC inhibition in two adherent (AD) squamous carcinoma cell lines (A431 and CaSki), with different proliferative and stemness potential, and in TIC...

The human epidermoid carcinoma cell line A431 has an usually high number of specific saturable receptor sites for the mitogenic polypeptide hormone epidermal growth factor (EGF). When A431 cells were treated with unlabeled EGF in the culture medium, approximately 50% of the EGF specific binding activity was lost within a few hours (receptor down regulation). A comparison of the surface proteins...

Several inhibitors of EGF receptor (EGFR) tyrosine kinase activity have been developed that compete with ATP at its binding site such as the quinazolines PD 153035 and ZD 1839 or the 4,5-dianilino-phthalimides DAPH1 and DAPH2. When tested on human A431 cells, the quinazolines completely blocked EGF-induced receptor phosphorylation at 100 nM, whereas it was inhibited by DAPH1 and DAPH2 by only 2...

Uptake of 2-[18F]-2-deoxy-D-glucose (FDG) has been used as a marker of increased glucose metabolism to visualize, stage, and monitor progression of human cancers with positron emission tomography. Many human tumors have been shown to overexpress the Glut-1 glucose transport protein. The aim of this study is to define whether a quantitative relationship exists between the amount of Glut-1 expres...

To investigate the anti-human epidermal squamous-cell carcinoma A431 cell proliferative fraction of Euphorbia fischeriana Steud. and to determine chamaejasmine B content in the fraction. Anti-A431 cell proliferative activity of various Euphorbia fischeriana Steud. fractions, which were extracted using ethanol extraction and with different solvents, were screened by MTT assay to identify the act...

Annexin VI is one of a family of calcium-dependent phospholipid-binding proteins. Although the function of this protein is not known, various physiological roles have been proposed, including a role in the budding of clathrin-coated pits (Lin et al., 1992. Cell. 70:283-291.). In this study we have investigated a possible endocytotic role for annexin VI in intact cells, using the human squamous ...

A431 human epidermoid carcinoma cells monophenotypically express the placenta! alkaline phosphatase (PLAP)-like enzyme shown by its catalytic and antigenic characteristics, properties which are shared by the Nagao isozyme. More specifically, it is L-leucine sensitive just as is the rare placenta! D-variant of PLAP and the testicular heat-stable enzyme. Collectively, these are all referred to as...

To explore bidirectional regulatory interactions between interferons and autocrine polypeptide factors, we examined the modulation of expression of transforming growth factor-a and 2’,5’-oligoadenylate synthetase activity in A431 epidermoid carcinoma cells after treatment with interferon-y and transforming growth factor-a. Treatment of A431 cells with interferon-y increased steady state levels ...