Modification of steroidogenesis in a mouse adrenal cell line (Y-1) transformed by simian adenovirus SA-7

Endocrine aspects of cancer gene therapy

The field of cancer gene therapy is in continuous expansion, and technology is quickly moving ahead as far as gene targeting and regulation of gene expression are concerned. This review focuses on the endocrine aspects of gene therapy, including the possibility to exploit hormone and hormone receptor functions for regulating therapeutic gene expression, the use of endocrine-specific genes as new therapeutic tools, the effects of viral vector delivery and transgene expression on the endocrine system, and the endocrine response to viral vector delivery. Present ethical concerns of gene therapy and the risk of germ cell transduction are also discussed, along with potential lines of innovation to improve cell and gene targeting.

Adenoviral vectors can impair adrenocortical steroidogenesis: clinical implications for natural infections and gene therapy

Recombinant adenoviral vectors are effective in transferring foreign genes to a variety of cells and tissue types, both in vitro and in vivo. However, during the gene transfer, they may alter the principal function and local environment of transfected cells. Increasing evidence exists for a selective adrenotropism of adenovirus during infections and gene transfer. Therefore, using bovine adrenocortical cells in primary culture, we analyzed the influence of different adenoviral deletion mutants on cell morphology and physiology. Transfection of cells with an E1/E3-deleted adenoviral vector, engineered to express a modified form of the Aequorea victoria green fluorescent protein, was highly efficient, as documented by fluorescent microscopy. Ultrastructural analysis, however, demonstrated nuclear fragmentation and mitochondrial alterations in addition to intranuclear viral particles. Basal secretion of 17-OH-progesterone, 11-deoxycortisol, and cortisol was significantly increased by E1/E3-deleted vectors; yet, the corticotropin-stimulated release of these steroids was decreased. Interestingly, neither purified viral capsids nor E3/E4-deleted adenoviral mutants altered basal and stimulated steroidogenesis of adrenocortical cells. An intact adrenal response is crucial for adaptation to stress and survival. Therefore, the implications of our findings need to be considered in patients with adenoviral infections and those undergoing clinical studies using adenoviral gene transfer. At the same time, the high level of transfection in adrenocortical cells might make appropriately modified adenoviral vectors suitable for gene therapy of adrenocortical carcinomas with poor prognosis.

Inhibitory or stimulatory effect of human genes on the expression of adrenal function in human Leydig X Y1 cell hybrids

In order to investigate the expression and the regulation of steroidogenesis, human Leydig cells were fused with a functional mouse adrenal cell line (Y1). Six independent hybrid clones were analysed for hormone receptors and for cAMP and steroid response to ACTH, hCG, 8Br-cAMP or forskolin. All hybrids had lost hCG receptors and their ability to produce testosterone. With respect to the response of adenylate cyclase to ACTH and/or forskolin, hybrids could be classed into two groups. In the first group, the pattern of response was qualitatively similar to Y1 parental cells; The second group was far less responsive to ACTH than are Y1 cells, and when added together, forskolin and ACTH only had an additive effect. All hybrids responded to ACTH and 8Br-cAMP with an increased production of pregnenolone (P5). The amounts of P5 produced both under basal conditions and following 8Br-cAMP stimulation were significantly higher in three hybrids when compared to Y1 cells. However, the ability of two of these three hybrids to produce 20 alpha-dihydroprogesterone (20 alpha OHP4) was very low. The metabolism of [14C]P5 revealed that in one of these hybrids, there was a loss of 3 beta-hydroxysteroid dehydrogenase/isomerase whereas in the other case, there was a low 20 alpha-hydroxylase activity. The inhibition of cell growth by ACTH was related to the ability of the hormone to stimulate cAMP. Conversely, the inhibitory growth effects of 8Br-cAMP were not always inversely correlated with the ability of this nucleotide to stimulate P5 production. Since hybrids contained two mouse genomes and retained variable human chromosomes, these results suggest that extinction or enhancement of murine genes coding for some of the enzymes involved in steroidogenic response to ACTH was due to the regulation by human genes.