Jerzy Trojan

Induction of apoptosis in rat hepatocarcinoma cells by expression of IGF-I antisense c-DNA

BACKGROUND/AIMS We have developed a gene therapy strategy based on the observation that insulin-like growth factor I (IGF-I) is necessary for the acquisition and maintenance of the transformed phenotype in hepatocarcinoma. This strategy consists in transfecting the rat hepatoma cell line with an episomal vector expressing the antisense IGF-I c-DNA under the control of the metallothionein I promoter inducible by zinc, decreasing therefore the level of IGF-I in these cells. The transfected clones lost their tumorigenic properties, and were able to induce, in vivo, the regression of an established tumor in syngeneic rats. To understand the loss of tumorigenic properties of these transfected clones, we have quantified, by different approaches, the number of apoptotic cells according to the level of IGF-I expression. METHODS IGF-I antisense synthesis in transfected cells was stimulated using zinc. We then characterized and quantified apoptosis, in these transfected clones, by morphological and DNA fragmentation analyses, flow cytometry and comet assay. RESULTS We have demonstrated that IGF-I inhibits the development of apoptosis in parental cells, that the transfected clones are able to restore the spontaneous apoptotic programme, and that apoptosis increases massively when overexpression of IGF-I antisense is caused by zinc stimulation of the metallothionein I promoter. CONCLUSION The present results allow us to conclude that the level of apoptotic pathway in liver cell lines is directly related to the amount of IGF-I deficiency.

In vitro Uptake of Exogenous α-Fetoprotein by Chicken Dorsal Root Ganglia

Exogenous chicken α-Fetoprotein (AFP) was added to embryonic chick dorsal root ganglia plated on gelatin-coated tissue culture dishes at different stages during the differentiation process and its int

Alpha-fetoprotein uptake by differentiating neuroretinal structures of the chick embryo.

Internalization of exogenous fluoresceinated alpha-fetoprotein (FITC-AFP) was studied at different stages of development on embryonic chick neural retinas maintained, for short periods, in organ cultures. Cellular localization of endogenous, native AFP was carried out by immunohistoperoxidase methods. Cells which specifically internalized exogenous FITC-AFP (neurons and their processes) were precisely those showing positive immunolabeling for the endogenous, native protein. Such a result supports the hypothesis of a predominantly exogenous origin of intracellular neuroretinal AFP. A precise topography and temporal sequence of AFP labeling after internalization in retinal structures is given. AFP uptake was not displayed by undifferentiated cell precursors or germinal cell layers but was apparent in cells with phenotypic characteristics of maturing neurons. Nerve fibers and synaptic layers actively internalized FITC-AFP at specific stages of development. Fully differentiated neurons and processes did not internalize AFP. The possible role of AFP, a carrier of biologically active substances such as fatty acids, in neural retina differentiation is discussed.

Methodology for Anti-Gene Anti-IGF-I Therapy of Malignant Tumours.

The aim of this study was to establish the criteria for methodology of cellular “anti-IGF-I” therapy of malignant tumours and particularly for glioblastoma multiforme. The treatment of primary glioblastoma patients using surgery, radiotherapy, and chemotherapy was followed by subcutaneous injection of autologous cancer cells transfected by IGF-I antisense/triple helix expression vectors. The prepared cell “vaccines” should it be in the case of glioblastomas or other tumours, have shown a change of phenotype, the absence of IGF-I protein, and expression of MHC-I and B7. The peripheral blood lymphocytes, PBL cells, removed after each of two successive vaccinations, have demonstrated for all the types of tumour tested an increasing level of CD8+ and CD8+28+ molecules and a switch from CD8+11b+ to CD8+11. All cancer patients were supervised for up to 19 months, the period corresponding to minimum survival of glioblastoma patients. The obtained results have permitted to specify the common criteria for “anti-IGF-I” strategy: characteristics sine qua non of injected “vaccines” (cloned cells IGF-I(−) and MHC-I(+)) and of PBL cells (CD8+ increased level).

A new putative target for antisense gene therapy of glioma: Glycogen synthase

The treatment of malignant brain gliomas remains a challenge, despite the availability of the classical triad of surgery, radiotherapy, and chemotherapy. There is thus the need for investigations into other forms of treatment strategies, such as gene therapy. Using antisense technology we have targeted glycogen metabolism, since malignant astrocytes present a high content of glycogen. In vitro rat C6‑glioma cells, transfected with antisense glycogen synthase (C6‑AS cells) exhibited a decreased expression of glycogen synthase and reduced activity of glycogen synthesis, along with attenuated invasiveness. In vivo tumors induced by C6‑AS cells in nude mice exhibited a significant reduction in tumor growth compared with controls. This reduction could be mediated by the induction of MCH‑I expression. The inhibition of glycogen synthesis by antisense glycogen synthase validates a putative target and a new approach for further study to advance the much‑needed efficacy of intervention strategies for malignant gliomas.

Endogenous and exogenous alpha-fetoproteins as differential markers of cultured neonatal mouse Schwann cells and fibroblasts

alpha-Fetoprotein (AFP) and AFP-gene transcripts were demonstrated in vitro in Schwann (S) cell and fibroblast (F) cell cultures of neonatal mouse origin. All S and F cells of primary cultures and of established cell lines expressed the AFP gene. AFP mRNA was detected by an in situ hybridization technique using a 35S-AFP-cDNA probe. AFP was localized by immunocytoperoxidase labelling using purified anti-AFP antibodies. The amounts of stained endogenous AFP, estimated semiquantitatively, were about 3-fold higher in S cells than in F cells. After incubating the cultures with exogenous mouse AFP, both S and F cells showed significant ability to take up the protein; the amount of internalized protein was found to be higher in F cells than in S cells. Moreover, the uptake of AFP fluorescein conjugates (FITC-AFP), estimated quantitatively by fluorometry, also gave higher values for F cells. The cytoplasm of F cells exhibited a characteristic fluorescence pattern, strongly illuminated and dispersed grains; the cytoplasm of S cells was regularly labelled. If exogenous FITC-AFP uptake could be used to distinguish labelled F cells from S cells (with application for identification and selection of F cells), the immunocytochemically stained endogenous AFP could allow S cells to be distinguished from F cells (using the dilutions of antibodies still staining the S cells but which lead to the absence of F-cell labelling). The two procedures, which can be used independently or together, may constitute differential markers for S cell and F cultures in, i.e., nerve regeneration of neurofibroma studies using the model of mixed S and F culture also containing other types of cells.

IGF-I biomarker testing in an ethical context

As we have come to know, there is a connection between cancer biomarkers and genes, along with their susceptibility to a particular disease, all of which have an obvious impact on the clinical practice and development of genetic testing. In any cancer disease, the diagnosis and treatment should be related to the investigation of specific biomarkers (generally antigens and proteins) and their corresponding genes. The study of different antigens such as alpha-fetoprotein, insulin-like growth factor I (IGF-I), insulin-like growth factor II, vascular endothelial growth factor, and epidermal growth factor, as well as their presence in neoplastic cells have demonstrated that IGF-I is an essential target for gene testing and therapeutic purpose. An over-expression of the IGF-I gene in mature tissues is a sign of neoplastic processes , e.g. brain or breast malignancy. A lot of questions have arisen regarding the ethics of gene testing, particularly concerns on the selection of patients for specific growth hormone/insulin-like growth factor I (GHIIGF-I) testing. Evidently, our current society is involved in a process of geneticization – the redefinition of individuals in terms of genetic codes. As such, we should take extreme care when making ethical judgments based on “scientific evidence” derived from genetic testing (typically those involving different biomarkers such as DNA, RNA, chromosomes, and proteins) in relation to genetic abnormalities that could predict current or future diseases. In this situation, the understanding of bioethics is of utmost importance.

Characterization of effector components from the humoral and cellular immune response stimulated by melanoma cells exhibiting modified IGF-1 expression

Modified melanoma B16 cells inhibited in their IGF-1 expression (B16MOD), on the contrary to the IGF-1 fully expressed parental wild-type (B16WT) counterpart, were shown to stimulate humoral as well as cellular immune responses. Among humoral components, the neutralizing and complement-fixing antibodies of IgM and essentially IgG2 (a+b) isotypes exhibited in vitro and in vivo effects upon tumour growth, while the IgG1 antibody isotype promoted enhanced tumour proliferation. As for the cellular immunity, it was found that the T CD8(+) lymphocyte subpopulation remained the main potent and long lasting immune active effector regulating tumour growth.