Systematic comparison of gene expression through analysis of cDNA fragments within or near to the protein-coding region

Fatty acid-binding protein 5 (FABP5)-related signal transduction pathway in castration-resistant prostate cancer cells: a potential therapeutic target

In this short communication, a novel fatty acid-binding protein 5 (FABP5)-related signal transduction pathway in prostate cancer is reviewed. In castration-resistant prostate cancer (CRPC) cells, the FABP5-related signal transduction pathway plays an important role during transformation of the cancer cells from androgen-dependent state to androgen-independent state. The detailed route of this signal transduction pathway can be described as follows: when FABP5 expression is increased as the increasing malignancy, excessive amounts of fatty acids from intra- and extra-cellular sources are transported into the nucleus of the cancer cells where they act as signalling molecules to stimulate their nuclear receptor peroxisome proliferator-activated receptor gamma (PPARγ). The phosphorylated or biologically activated PPARγ then modulates the expression of its downstream target regulatory genes to trigger a series of molecular events that eventually lead to enhanced tumour expansion and aggressiveness caused by an overgrowth of the cancer cells with a reduced apoptosis and an increased angiogenesis. Suppressing the FABP5-related pathway via RNA interference against FABP5 has produced a 63-fold reduction in the average size of the tumours developed from CRPC cells in nude mice, a seven-fold reduction of tumour incidence, and a 100% reduction of metastasis rate. Experimental treatments of CRPC with novel FABP5 inhibitors have successfully inhibited the malignant progression of CRPC cells both in vitro and in nude mouse. These studies suggest that FABP5-related signal transduction pathway is a novel target for therapeutic intervention of CRPC cells.

High-level expression of cutaneous fatty acid-binding protein in prostatic carcinomas and its effect on tumorigenicity

The expression of cutaneous fatty acid-binding protein (C-FABP) in prostate tissues was examined by immunohistochemistry. Among the 76 cases, all seven (100%) normal tissues were unstained. Of the 35 benign prostatic hyperplasia (BPH), 25 (71.4%) specimens were unstained and 10 (28.6%) were stained positively. For the 34 prostatic carcinomas, the C-FABP expression was remarkably increased: 25 (73.5%) samples stained positively, and only nine (26.5%) were unstained. Transfection of a vector expressing an antisense C-FABP transcript into the PC-3M prostatic cancer cells yielded two transfectant lines: PC-3M-CFABP-1 and PC-3M-CFABP-3, producing, respectively, a 3.8- and a 6.9-fold reduction in C-FABP levels. Comparing with the control transfectants, the in vitro invasiveness of both PC-3M-CFABP-1 and PC-3M-CFABP-3 was significantly reduced. When tested in nude mouse, the average size of tumours produced by PC-3M-CFABP-1 and by PC-3M-CFABP-3 was reduced by 2.9- and 4.2-fold respectively, in comparison with that of tumours produced by the control transfectants. Analysis showed that the decreased vascular endothelial growth factor (VEGF) and microvessel densities in the tumours were associated with the reduced C-FABP. These data show that C-FABP is increased in prostatic carcinoma cells and suppression of its expression can significantly inhibit the tumorigenicity, probably by reducing the expression of VEGF.

A novel strategy for identifying differential gene expression: An improved method of differential display analysis

We propose a novel alternative approach, an advanced method for recently developed strategies, for identifying differentially expressed genes. Firstly, double-stranded cDNAs were digested using Sau3AI and the 3'-end restriction fragments of the cDNA were ligated to a double-stranded adapter. Next, the restriction fragments were directly amplified using several combinations of adapter-specific primers and FITC-labeled oligo dT primers. The selected cDNA fragments were displayed on a polyacrylamide gel. Neither nested PCR nor purification of 3'-end fragments are necessary. We examined the validity of this approach by evaluating gene expression changes during granulocytic differentiation of HL-60 cells. This method can theoretically detect almost all gene expression changes more rapidly and through simpler manipulations than by any other approach.