Insulin-like growth factor I receptor cDNA cloning

Micro-array analysis of the effect of post-transurethral bladder tumor resection urine on transforming growth factor-β1 dependent gene expression in transitional cell carcinoma☆

INTRODUCTION AND OBJECTIVES

Prior studies have shown that bladder trauma occurring during transurethral bladder tumor resection increases urinary levels of the cytokine transforming growth factor (TGF)-beta1. This study used complementary deoxyribonucleic acid micro-array technology to identify additional genes in human transitional cell carcinoma (TCC), whose expression is altered as a consequence of increased urinary levels of TGF-beta1.

METHODS

The human TCC line 253J was cultured in standard media, or media spiked with either 10% post-transurethral bladder tumor resection urine (PTU), or PTU and anti-TGF-beta1 neutralizing antibody. Messenger ribonucleic acid from these conditions, together with messenger ribonucleic acid from stably transfected 253J cells over-expressing TGF-beta1, was hybridized with ATLAS micro-array membranes (Clontech, Palo Alto, CA) containing 588 human genes. Hybridization signal intensity was quantified using phospho-imaging. An analytic strategy based on the variance in the signal intensity ratio of specific housekeeping genes in control and experimental comparisons was used to identify significant changes in gene expression. Reverse transcriptase polymerase chain reaction of target genes was used to confirm gene over-expression and TGF-beta1 responsiveness.

RESULTS

Seven genes were identified on micro-array: v-RAF-1, colony stimulating factor-1 receptor, v-FGR, insulin growth factor-1 receptor, epidermal growth factor receptor, alpha5 integrin, and interferon receptor-1. Reverse transcriptase polymerase chain reaction confirmed over-expression in the autocrine TGF-beta1 producing cell line and increased expression in response to exogenous TGF-beta1.

CONCLUSIONS

TGF-beta1 in PTU alters the expression of multiple genes in human TCC in vitro. The impact of these changes on the biologic phenotype of the malignant cell and the efficacy of adjuvant therapies requires further evaluation.

Type I insulin-like growth factor receptor gene expression in normal human breast tissue treated with oestrogen and progesterone

The epithelial proliferation of normal human breast tissue xenografts implanted into athymic nude mice is significantly increased from basal levels by oestradiol (E2), but not progesterone (Pg) treatment at serum concentrations similar to those observed in the luteal phase of the human menstrual cycle. Type I IGF receptor (IGFR-I) mRNA and protein have been shown to be up-regulated by E2 in MCF-7 breast cancer cells in vitro in which IGF-I and E2 act synergistically to stimulate proliferation. We have investigated the expression of the IGFR-I mRNA in normal human breast xenografts treated with or without E2 or Pg alone and in combination. Northern analysis of 20 micrograms of RNA extracted from the breast xenograft samples showed no hybridization with 32P-labelled IGFR-I probe, although an 11-kb species of IGFR-I mRNA could be seen when 20 micrograms of RNA extracted from either MCF-7 breast cancer cells or human breast carcinomas was examined in this way. In order to analyse the expression of IGFR-I mRNA in breast xenografts, a quantitative reverse transcription-polymerase chain reaction (RT-PCR) was employed in which RNA loading, reverse transcription and PCR efficiencies were internally controlled. The data indicate that the IGFR-I mRNA is up-regulated by two to threefold compared with untreated levels by 7 and 14 days E2 treatment. In contrast, 7 or 14 days Pg treatment down-regulates the receptor mRNA to approximately half that of untreated levels, whereas combination E2 and Pg treatment produced a twofold increase in IGFR-I mRNA levels compared with untreated tissue. The results are consistent with the suggestion that E2 may act to stimulate proliferation indirectly via a paracrine mechanism involving IGFs in normal as well as malignant human breast epithelial cells.

Expression of mRNAs of multiple growth factors and receptors by neuronal cell lines: detection with RT-PCR

Neurons and glia are capable of both secreting and responding to a large variety of growth factors. However, information on multiple expression of growth factors and their receptors was usually obtained from uncorrelated observations, using cells from various animals of origin, developmental stages, growth phases, culture ages and culture conditions. Because of its specificity and extreme sensitivity, reverse transcription-polymerase chain reaction (RT-PCR) is uniquely suitable to study a large panel of growth factors and their receptors from a limited cell sample, free of these intervening variables. In this paper we evaluate the expression of mRNA of a total of 35 growth factor-related proteins by conducting RT-PCR on three neuronal cell lines: the PC12 rat pheochromocytoma line, the MAH rat sympathoadrenal progenitor line, and the N18 mouse neuroblastoma line. Three types of results are presented. The first confirms the existing knowledge such as the presence of Trk-A (NFG receptor) in PC12. The second consists of new information that expands and extends earlier observations, such as the presence of CNTF receptor complex in PC12, which explains our previous report that CNTF enhances the biological effects of NGF on these cells. The third consists of novel information that leads the way to further experimentation by the more conventional methods. These include the strong expression of Trk-B by MAH, predicting the biological responsiveness of MAH to BDNF and NT-4, and the expression of CNTF receptor in N18. Our results also suggest that CNTF is an autocrine factor for PC12 and MAH, since both lines express the growth factor as well as the receptor. Thus, RT-PCR is a valuable tool in growth factor research that can be used in complement to, and interactively with, other approaches such as bioassay, receptor binding, and immunochemical determination. It will be particularly useful for screening a large number of growth factors in minute areas of the brain in patients suffering from neurodegenerative diseases such as Parkinson's and Alzheimer's.

Expression of mRNAs of multiple growth factors and receptors by astrocytes and glioma cells: detection with reverse transcription-polymerase chain reaction

1. Although glial cells in culture are known to secrete growth factors and are also known to be responsive to some of them, detailed comparisons are difficult because the bulk of information was based on various animals of origin, developmental stages, growth properties, culture age, and culture conditions. 2. To present a unified picture of the growth factors and their receptors found in glial cells, we surveyed the expression of messenger RNAs of a panel of growth factors and receptors, using reverse transcription-polymerase chain reaction (RT-PCR), in three common glial cell types: rat astrocytes in primary culture, rat glioma line C6, and human glioma line A172. 3. We observed that normal and neoplastic glial cells in culture express multiple growth factors and also possess most of the receptors to the factors, suggesting multiple autocrine functions. In addition, glia produce growth factors known to be capable of acting on neurons, implicating paracrine function involving glia-neuron interaction. Glial cells also produce growth factors and receptors that are capable of communicating with hematopoietic cells, suggesting neuroimmunologic interaction. What is most interesting is that glial cells express receptors for growth factors previously thought to be acting on neurons only. 4. The current study demonstrates the feasibility of screening from a small sample a large number of growth factors and receptors. The method portends future clinical application to biopsy or necropsy samples from brain tumors or pathologic brains suffering from degenerative diseases such as Alzheimer's or Parkinson's disease.