Myeloblastin (mbn) is a serine protease involved in the control of growth and differentiation of human leukemic cells. In the promyelocytic-like human leukemia cell line HL-60 this protease is inhibited during retinoic acid (RA) induced differentiation. The t(15;17) translocation, specifically associated with the human acute promyelocytic leukemia (APL), fuses the retinoic acid receptor alpha (RAR alpha) to a novel gene PML generating the hybrid protein PML-RAR. We have shown that while mbn was early down-regulated in HL60 cells treated with all trans RA, the inhibition of this gene was considerably delayed in NB4 cells, which carry the t(15;17) translocation, upon treatment with the same inducer. This observation suggested that the changes in the myeloblastin regulation by RA found in NB4 cells could be ascribed to the presence of the fusion protein PML-RAR. To verify this hypothesis we have cloned the putative promoter region of mbn gene. Transactivation properties of endogenous retinoic acid receptors on this region have been tested in transfection experiments of HL60 and NB4 cell lines before and after treatment with all trans RA. We found that RA induced a significant inhibition of the luciferase reporter gene in HL60 cells. In contrast, a strong stimulation of luciferase activity was observed in NB4 cells treated with RA. The analysis of the promoter region allowed us to identify a new response element for retinoic acid receptors, named mREpal, which is probably affected by the product of t(15;17) translocation.

Acute promyelocytic leukemia is a key model system in Cancer biology. Its ability to differentiate upon exposure to retinoic acid constitutes the first example of differentiation therapy. The molecular basis of leukemogenesis is the PML/RAR fusion resulting from the t(15, 17) translocation. The fusion protein likely acts through interference with the function of nuclear receptors (resulting in a differentiation block) and also through interference with PML which appear to be a growth suppressor. The exquisite sensitivity of this disease to retinoic acid represents the first example of a therapy directly targeted at a specific and causative genetic lesion.

Usual treatments combining surgery, radiation therapy, chemotherapy and hormonotherapy are poorly effective. The immunotherapy gave and objective response rate of 25% but is associated with many side effects. Multidrug resistance (MDR) can be explained, in part, by an mdr1 gene overexpression in renal carcinoma. The MDR is related to expression of a 170 Kda membrane glycoprotein, the so-called P glycoprotein (Pgp). This protein is able to extrude from cytoplasm drugs with various structures and mechanisms. Reversal compounds capable of inhibiting Pgp, given with antineoplastic drugs, could be able to increase their intracellular concentrations. Nevertheless, renal cell carcinomas are characterized by their multifactorial resistance and a better knowledge in this field will allow to design new circumvention resistance to chemotherapy.

A complex translocation involving chromosome 6, 8 and 9 [t(6;9;8)(p23;q34;q22)] associated with other structural and numerical abnormalities was observed on bone marrow karyotype of a woman suffering with acute myeloblastic leukemia (AML2). Fluorescence in situ hybridization agreed with the conventional cytogenetic interpretation by showing that a part of chromosome 6 short arm was inserted on the rearranged chromosome 9 resulting in the t (6;9) usually encountered in AML.

The "Groupe d'Etude des Néoplasies Endocriniennes Multiples de type 1 (GENEM 1)" is a French group involved in a comprehensive multicentre study of Multiple Endocrine Neoplasia type 1 syndrome (NEM 1). The objectives of this group are to define diagnostic and therapeutic protocols and to carry out genetic research on NEM1. The first aim of physicians is to recognize the syndrome and to determine the appropriate screening especially into two circumstances: 1 degree In case of isolated and sporadic glandular disease -i-e-parathyroid glands, endocrine pancreas, antehypophysis, adrenal glands and neuroendocrine tumors? 2 degrees In case of very high probability of NEM 1 syndrome? This paper answers these two questions, based on the analysis of the first 150 cases collected by the GENEM 1.

Carcinogenesis is a multigenic phenomenon where 3 prevailing types of genes are involved: oncogenes which stimulate the cell proliferation, tumor suppressor genes which act as inhibitors and metastagenes which contribute to the tumor progress. In animal models it has been shown that epithelial skin carcinogenesis proceeds stepwise: initiation, promotion, premalignant progression and finally malignant conversion. The oncogene c-H-ras and the tumor suppressor gene P53 are the genes whose involvement in these steps of epithelial skin cancers are duly established. Less experimental data are available concerning melanoma. the role of the oncogene N-ras, the tumor suppressor gene MTS-1 (encoding for protein p16) ans the metastagene nm 23 has recently be emphasized. Some cytogenetic abnormalities on chromosomes 1, 6, 9, 10, 11 and 17 have also been observed and incite to look for other genes potentially involved in the development of this tumor.

Various gene systems are involved in events occurring during transformation of a normal cell into a cancer cell. By order of intervention, genes responsible for an increased individual susceptibility to cancer can be distinguished from actual cancer genes, followed by genes involved at other levels of carcinogenesis. 15 to 20% of patients with breast cancer have a first-degree relative affected by the same cancer, although an inherited predisposition to cancer is only established in 4 to 10% of cases. The genetic heterogeneity of familial forms of breast cancer make it difficult to identify susceptibility genes. At the present time, 3 regions of the genome have been implicated in the predisposition to breast cancer in women: the BRCA1 gene, the BRCA2 gene and the TP53 gene. All predisposition genes are able to transmit susceptibility due to a mutation or inherited microdeletion.

For the past decade, primary chemotherapy has been extensively used in breast cancer treatment. However, valuable indicators of tumor response are needed. Fine-needle cytopuncture allows the study of malignant cells by cytologic examination, image analysis and flow cytometry. Some parameters evaluated before treatment (cytologic grade, nuclear area and S phase) or at the beginning of treatment (cytomorphologic and cell kinetic changes) have been shown to be correlated with tumor response. The methods, their value and limitations, and results of the literature are discussed.

It is shown that breast cancer can be considered as a paradigm of comprehensive cancer biology and treatment based on analysis of each individual tumor. Historically, it was first observed in breast cancer that tumor progression could be dependent on factors regulating physiological activities (i.e. hormones). It was also observed that tumor growth progressively becomes autonomous, through successive degradation of the multiple steps involved in the control of cell proliferation and differentiated activities. Hormonal treatment of breast cancer provided the first example of targetted biotherapy. The discovery of the mechanism of action of hormones via specific receptors opened the field of tumor tissue analysis to determine the main biological factors involved in tumor progression. In the near future, such data should be the best guide for selection of the most appropriate treatment in each individual case.

The authors studied DNA content in a case of small cell carcinoma with hypercalcemia. This tumor exhibited typical clinical, histological, immuno-histochemical, ultrastructural and biological patterns. DNA content was measured both by flow and image cytometry performed on unfixed tumoral samples. The proliferation index was 10%. These results are similar to those of the literature obtained retrospectively from 10% formalin fixed tissues. The DNA content is a clue to distinguish this entity from other small cell carcinomas of the ovary because immunohistochemical findings are not always informative. The diagnosis of small cell carcinoma of hypercalcemic type should be questioned if DNA content is abnormal.

The purpose of this review is to study the literature concerning normal colon and colorectal cancer for evidencing that the location of the primary proximal or distal tumor may determine two categories of carcinogenesis. The proximal or distal normal colon can be considered as two different organs. Their embryologic origins are different, the splenic flexure starts the distal segment. Antigenic pattern as well as the use of metabolic pathways, such as that of glucose, butyrate and polyamines differ. Epidemiologic, macroscopic and histological features and the inherited and acquired genetic abnormalities allow in some cases to distinguish between two types of cancer according to their proximal or distal location. These two forms are not entirely different and these features can overlap. However the recognition of these two different forms of colon cancer, must be taken in account for clinical or basic research and evaluation of data.

Cell cycle progression is regulated by the sequential activation of cyclins expression and their association to the cyclin dependent kinases (CDK). Several in vitro and in vivo studies indicate that inappropriate cyclin expression (cyclins D, E, A) in the cell, whether or not due to chromosomal rearrangements, can participate in cell transformation. Thus these studies implicate cyclins in human carcinogenesis.

A biphasic synovial sarcoma occurring in the anterior and inferior mediastinum in a 19-year-old woman is reported. A biopsy showed a mesenchymal proliferation and the tumor was first misdiagnosed as a hemangiopericytoma. Inefficacy of chemotherapy led to a tumorectomy. Histologic and immunohistochemical studies on multiple samples showed a biphasic tumor. Ultrastructural study confirmed the presence of epithelial elements and cytogenetic analysis disclosed a translocation t(X;18) (p11;q11), leading to a diagnosis of synovial sarcoma. Synovial sarcoma of the mediastinum is very rare and to our knowledge has not been previously studied with the help of cytogenetics. Given the biphasic pattern of the tumor and its mediastinal location, it can be confused with mesothelioma. This stresses the interest of chromosome analysis in the study of tumors histologically difficult to classify.