Drug resistance is a major obstacle to successful chemotherapy for cancer. When it occurs, resistance to a wide range of agents is noted. Factors that rule this resistance can be defined as pharmacologic and cellular. Pharmacologic factors are those that prevent an adequate degree of tumor cell exposure and include considerations of dose and schedule of drugs. Cellular factors are those that imply the tumor cell itself and it is probable that multiple mechanisms co-exists: 1) the drug transport across the tumor cell membrane and the duration of the drug exposure, 2) the drug metabolism (activation, inactivation), 3) the cellular targets and the DNA repair processes. The pleiotropic multidrug resistance (mdr, mrp, lrp), alterations of a target enzyme (topoisomerase II, protein kinase C, glutathione S transferase, O6 alkylguanine-DNA alkyltransferase) and the protein modifications (heat shock protein, metallothioneins) are the principal mechanisms involved. Several methods have been established for the determination of the presence of these drug resistance mechanisms but variations in the results are observed with the different methods used. Therefore, the value and the relative importance of these mechanisms in human tumor resistance is not yet established. In the mean-time, strategies to prevent and to overcome this resistance are developed.

PML is a protein involved in the t (15, 17) translocation of promyelocytic leukemia and is mainly localized in nuclear bodies. Here we show that PML exerts a very powerful enhancing activity (up to 20-fold) on the transactivating properties of the progesterone receptor (PR) and has a similar effect on several other steroid hormone receptors. There is probably a direct or indirect interaction between PR and PML since when the latter was expressed at high concentrations it shifted PR into the nuclear bodies. Use of deletion mutants showed that both activation functions (AF1 and AF2) of PR as well as the coiled coil and His-Cys rich domains of PML were required for transcriptional enhancement. The fusion protein PML-RAR, which is not localized in nuclear bodies, also enhanced the transactivating activity of PR but this effect was totally suppressed by the administration of retinoic acid. PML, which is ubiquitously expressed, may thus be involved in the transactivation properties of steroid hormone receptors. This mechanism may also play a role in the oncogenic properties of PML-RAR and in their suppression by the retinoic acid.

Recently we demonstrated that rat glioma cells when transfected with a vector encoding antisense IGF-I c-DNA lost tumorigenicity and induced a tumor specific immune response involving CD8+ lymphocytes. Here we showed, using immunostaining flow cytometry analysis, that the transfected cell lines, rat C-6 glioma and rat LF hepatoma, expressed an increase level of MHC-class I, and even the amount of MHC-I was found to be higher in the transfected hepatoma, than in the transfected glioma cells. This increased expression of MHC-I could contribute to the final immune recognition of tumour immunogenicity.

A case of gastric hyperplastic polyposis is reported in a 48-year old woman, with iron deficiency anemia. An hyperplastic gastric polyposis was discovered. This patient had been operated 17 years previously for a large adenomatous polyp of the caecum. Her son had also several adenomatous polyps of the right colon. A gastrectomy was performed. Hyperplastic gastric polyposis is very rare, and is quite always associated with colorectal adenomas. The relationship between gastric hyperplastic polyposis and intestinal polyposis is not quite clear.

Hürthle cell cancers of the thyroid have been a subject of debate for many years because it is difficult to differentiate between benign and malignant tumours. Diverse therapeutic strategies have thus ensued. Recent work describing the morphologic and biologic criteria for a more precise diagnosis have led to better therapeutic strategies. We report a series of 85 tumours of the thyroid with Hürthle cells including 19 Hürthle cell tumours (22%) operated between 1976 and 1994. Hürthle cell tumour represented 6.7% of 282 thyroid cancers operated during the same period. The mean age of the patients was 56.6 years (range 23 to 78 years) and 63% of the tumours were large > or = 4 cm (classed T3T4). Treatment was total thyroidectomy in 79% of the cases. 5-year survival was 58.3% and 25% of the cases had metastatic extension at the time of initial treatment. Hürthle cell cancer have now been recognized as a particular anatomic and clinical entity. They were formerly confounded with vesicular cell cancers but now have been separated into a single entity due to a poor prognosis, lack of response to radioactive iodine and high incidence of metastasis. The current histological criteria make diagnosis more precise and allow more logical treatment with total thyroidectomy. A few familial cases have been reported. Although less frequent than in medullary cancer, this form would suggest that a genetic survey should be conducted for this particular type of thyroid cancer.

In patients successfully treated for hereditary retinoblastoma, the risk of developing a second non-ocular tumor has been reported. We report the first case of primary hepatic leiomyosarcoma in a 39 year-old woman who has been treated 37 years before for hereditary retinoblastoma of the left eye. The patient presented with right upper quadrant abdominal pain and fever. Histological diagnosis was made by liver biopsy. As surgical resection was impossible, chemotherapy with epirubicin, then ifosfamide, etoposide and cisplatin was performed. The patient died 22 months after diagnosis. Genetic abnormalities observed in hereditary retinoblastoma, which probably resulted in a predisposition to the development of hepatic cancer in this patient, were not investigated.

p53 tumor suppressor gene is involved in the development of esophageal cancer. However, its role is not precisely defined in the two types of cancer, squamous cell carcinoma and adenocarcinoma developed in Barrett's esophagus. The aim of this work was to compare the frequency and type of mutation of the p53 gene and the expression of the p53 protein in a series of 21 squamous cell carcinomas and 27 adenocarcinomas of the esophagus in a single institution. p53 protein accumulation was assessed by immunohistochemistry with the monoclonal antibody PAb 1801. The mutations of exons 5 to 8 of p53 gene were detected by denaturating gradient gel electrophoresis, and sequenced.

Xeroderma pigmentosum (XP) is a rate autosomal recessive disorder related to DNA repair defects. Recently, modifications of oncogenes and mutations of the p53 suppressor gene have been reported in skin tumors of XP patients. The purpose is to study, through a series of 40 patients admitted to the Dermatologic Clinic of Algiers, the characteristics of XP in Algeria.

Multiple Endocrine Neoplasia type 1 (MEN 1) is an autosomal dominant familial syndrome characterized by involvement of several endocrine glands, including parathyroid, pancreatic islet cells, anterior pituitary and diffuse neuroendocrine tissues (carcinoids). The gene causing this syndrome has been localized to chromosome 11 but was not cloned up-to-date. Pre-clinical diagnosis in predisposed MEN 1 families was based on the use of genetic linkage analysis with polymorphic DNA probes flanking the disease locus. The set-up collaborative multi-disciplinar medical and surgical network facilitates further clinical and genetic studies on MEN 1 families. Semiological course of the disease is complex and the main objective in clinical follow-up of patients and related is to limit the probability of misdiagnosis. The present report describe the clinical and genetic analysis in a MEN 1 family and the difficulties related to diagnose the disease. An interesting observation on two cases of hyperprolactinemia by two individuals further excluded by genetic analysis assess the potential risk of bias in genetic linkage studies in non-well documented families. Concerted analysis of genetic and bio-clinical data permitted the evaluation of each patient and to exclude the risk of MEN 1 in all children tested. This example demonstrates the need of a complete clinical information previously to genetic analysis and a multi-disciplinar and collaborative approach in follow-up of patients in each family.

MTC occurs sporadically or as part of multiple endocrine neoplasia type 2 (MEN 2) syndromes or as familial MTC (FMTC). 97% of the patients affected with MEN 2B show a germline mutation in codon 918 (exon 16) within the tyrosine kinase domain of the RET protooncogene. In 97% of MEN 2A patients, the germline mutation affects one of five cysteine codons within exons 10 and 11 in the extracellular domain. Only 65% of FMTC patients are found to have a germline mutation of RET. These mutations affect either the cysteine rich domain (as MEN 2A mutations) or codons 768 (exon 13) or 804 (exon 14) within the tyrosine kinase domain. In families affected with hereditary form of MTC, mutation analysis is now commonly used to determine genetic status. Individuals without the mutation would be considered unaffected and would not require further biochemical screening. Individuals who inherit the MEN 2 mutation would undergo biochemical screening tests and have thyroidectomy as soon as these tests are abnormal. Risk of phaeochromocytoma in affected patients depends on the position of RET mutation. This risk is high if the patient has a codon 634 mutation and low if he has a mutation within exon 10, 13 or 14. Frequency of adrenal follow-up could so be adapted with regards to the localisation of RET germline mutation. When a new MTC case is diagnosed, the distinction between a true sporadic and a de novo hereditary case is important for future clinical management of both the patient and his family. The absence of RET exons 10, 11, 13, and 14 germline mutations appears to rule out MEN 2A to a high probability. However the presence of a familial form of MTC cannot be excluded conclusively. Since codon 918 somatic mutations are found in 25% of MTC from truly sporadic cases, mutation analysis of RET in tumour DNA may help in distinguishing the sporadic cases from those that are in fact heritable.

2260 patients with medullary thyroid carcinoma have been registered in France in 1995 by the GETC group. Main characteristics of the disease are reviewed in this paper. Many problems remain concerning screening, localisation of metastases and non surgical treatment.

The aim of this study was to assess the main clinical biochemical and immunocytochemical factors influencing survival in 51 patients operated for medullary thyroid carcinoma (MTC). There were 55% of women and 37% of familial cases. Mean age was 43 +/- 3 years. The following survival variables were tested: sex, age, stage, familial disease, Serum Carcino Embryonic Antigen (CEA) and Calcitonin (CT) levels three months postoperatively, intensity of CEA and CT immunostaining, percentage of cells stained for CEA and CT. The actuarial survival rate, including postoperative mortality (N = 1), was studied by uni and multivariate analysis using a Cox model (N = 31). The 5-year survival was 69 +/- 7%. By univariate analysis, stages I or II (p < 0.0001), age of 45 years and less (p < 0.0001), normalized CEA levels (p < 0.006), percentage of CT stained cells greater than 80% (p < 0.04) and weak CT and CEA staining (p < 0.02) were significant predictors of increased survival rates. Age less than 45 and stages I or II were significant prognostic factors of goof survival on multivariate analysis (p < 0.001). We conclude that clinical criteria constitute good survival prognostic factors in patients operated for MTC. The better prognosis of familial cases was probably related to their earlier detection. The prognostic value of immunostaining remains controversial and requires further studies.

Chronic myeloid leukemia (CML) is a clonal myeloproliferative disorder of a stem cell, involving myeloid, erythroid, megacaryocyte, lymphoid B-cells and "natural killer" cells. The hallmark of CML is the Philadelphia (Ph) chromosome which is a shortened chromosome 22 (22q-) resulting from a reciprocal translocation involving chromosome 9 and chromosome 22, designed t (9;22) (q34;q11). This translocation juxtaposes parts of two genes; ABL on chromosome 9 and BCR (breakpoint cluster region) on chromosome 22. Transcription of the BCR/ABL fusion gene results in an hybrid mRNA that is translated into a 210 kDa or 190 kDa protein, depending on the location of the breakpoint in the bcr region. This protein plays a key role in CML: its tyrosine-kinase activity, that differs from the normal ABL product, may be involved in leukemic cell growth. Nonetheless, the loss of the negative cell growth regulation by c-ABL, or BCR/ABL fusion protein interaction with other cellular genes (such as RAS or c-MYC) could also be involved in CML pathophysiology. A better understanding of the molecular mecanisms of CML could lead to specific treatment, such as tyrosine-kinase inhibitors, synthetic oligodeoxynucleotides, or site-specific DNA-binding proteins designed against BCR/ABL oncogenic fusion sequence.

Blau syndrome is a granulomatous disease with dominant autosomal transmission. Skin, joint and ocular manifestations usually appear in childhood.

A certain percentage of cancers are primarily or subsequently resistant to chemetherapeutic agents. Several biological mechanisms are implicated in this phenomenon, including multidrug resistance/P-glycoprotein (mdr1/P-gp), resistance related proteins (P-95 and P-110), multidrug resistance associated protein (P-190), iso-enzymes of gluthatione S-transferase, topo-isomerases, glutathione peroxidase and others. mdr1/P-gp overexpression has been studied in many types of cancer. It represents an inducible, transferable and phylogenetically ancestral biological system. It is expressed at the surface of the cell, and in that way, it participates to several normal functions. The recent introduction of modulators/revertants of mdr1/P-gp may change some concepts in using chemotherapy for cancers. The first step is represented by a better knowledge of the cancers which overexpressed mdr1/P-gp, with determination of the best biological technique, including the gold standards. This allows the clinician to clarify the best impact of such a therapeutic way and to define the criteria of modulator selection. Such criteria includes in vitro selection using a panel of sensitive/resistant cell lines, in vivo tests including transgenic mice, nude or SCID mice, and toxicological studies. Choice of modulated drug is easier and depends on the biological target. For mdr1/P-gp, major drugs included doxorubicin and vinca-alkaloids. Due to the fact that some modulators have an influence on the pharmacokinetic parameters of chemotherapeutic drugs, it is important to verify such parameters. The last choice concerns the strategy of drug development with three levels of action: 1) modulation of clinical chemoresistance, intrinsic or acquired one; 2) modulation of biological resistance; 3) leading to the prevention of the amplification of low levels of chemoresistance. A new therapeutic way is born, which takes care of a dynamic aspect of the tumor, and necessitates a new use of chemotherapy.