Silicone particles in capsules around breast implants: Establishment of a new pathological methodology to assess the number of particles around breast implants.

INTRODUCTION: The presence of silicone particles in breast implant capsules has been observed since the 1970s. Since then, little data has been published regarding the amount of silicone that is susceptible to migrate into the capsule. Quantifying the amount of silicone migration from the implant to the capsule could inform on the level of silicone exposure a patient with breast implants may experience in the short- or long-term. The objective of this study is to present a histological quantification methodology of the number of silicone particles present in breast implant capsules. MATERIALS AND METHODS: A prospective study was performed on capsule samples from patients requiring revision surgery. The slides were digitalized and analyzed with a viewer software. For each sample, we (1) manually counted each silicone particle, (2) measured the average particle size, (3) measured the capsule surface area, and (4) calculated the particle number density in each capsule sample. The average of all capsule samples' particle number densities was then compared to the total volume of the capsule to estimate the total number of silicone particles found within the capsule of each breast implant. RESULTS: Six capsules from six different patients were analyzed. Two capsules were from saline implants while four capsules were from silicone implants. All four silicone implant capsules contained between 352,928 and 9,002,235 silicone particles. The particle number density ranged from 20.5 to 683.5 particles per mm3 of capsule. The two saline-filled implant capsules were free of silicone particles. The average of all capsule samples' particle number densities was then compared to the total volume of the capsule to estimate the total number of silicone particles found within the capsule of each breast implant. CONCLUSIONS: We describe a new and reproducible methodology to quantify realistically the silicone particles in the periprosthetic capsule of breast implants.

Celastrol protects ischaemic myocardium through a heat shock response with up-regulation of haeme oxygenase-1.

BACKGROUND AND PURPOSE: Celastrol, a triterpene from plants, has been used in traditional oriental medicine to treat various diseases. Here, we investigated the cardioprotective effects of celastrol against ischaemia. EXPERIMENTAL APPROACH: Protective pathways induced by celastrol were investigated in hypoxic cultures of H9c2 rat cardiomyoblasts and in a rat model of myocardial infarction, assessed with echocardiographic and histological analysis. KEY RESULTS: In H9c2 cells, celastrol triggered reactive oxygen species (ROS) formation within minutes, induced nuclear translocation of the transcription factor heat shock factor 1 (HSF1) resulting in a heat shock response (HSR) leading to increased expression of heat shock proteins (HSPs). ROS scavenger N-acetylcysteine reduced expression of HSP70 and HSP32 (haeme oxygenase-1, HO-1). Celastrol improved H9c2 survival under hypoxic stress, and functional analysis revealed HSF1 and HO-1 as key effectors of the HSR, induced by celastrol, in promoting cytoprotection. In the rat ischaemic myocardium, celastrol treatment improved cardiac function and reduced adverse left ventricular remodelling at 14 days. Celastrol triggered expression of cardioprotective HO-1 and inhibited fibrosis and infarct size. In the peri-infarct area, celastrol reduced myofibroblast and macrophage infiltration, while attenuating up-regulation of TGF-ß and collagen genes. CONCLUSIONS AND IMPLICATIONS: Celastrol treatment induced an HSR through activation of HSF1 with up-regulation of HO-1 as the key effector, promoting cardiomyocyte survival, reduction of injury and adverse remodelling with preservation of cardiac function. Celastrol may represent a novel potent pharmacological cardioprotective agent mimicking ischaemic conditioning that could have a valuable impact in the treatment of myocardial infarction.

Clinical and biochemical features of seven adult adrenal ganglioneuromas.

BACKGROUND: Adrenal ganglioneuroma (GN) is seldom considered in the differential diagnosis of adrenal lesions, and its clinical presentation is not well known. OBJECTIVE: Our aim was to describe the clinical, biochemical, and radiological features of adrenal GNs in adults. METHODS: Seven adults underwent endocrine investigation for adrenal lesions that were confirmed to be adrenal GNs. RESULTS: Mean age of the seven patients was 49 yr (range, 23 to 71 yr). Average tumor diameter was 5.0 cm (range, 1.5 to 10.4 cm). In five patients, the adrenal lesions were found incidentally. A 49-yr-old female carried a germline mutation in MSH2 gene. A 57-yr-old female presented with mild virilization and increased testosterone levels. Bilateral adrenal venous sampling revealed testosterone production from her right adrenal lesion. All tumors showed nonenhanced attenuation between 25 and 40 Hounsfield units on computed tomography scan. Magnetic resonance imaging revealed low- to iso-signal intensity on T1-weighted imaging and high-signal intensity on T2-weighted imaging. [(18)F]-2-Fluoro-deoxy-d-glucose-positron emission tomography scan (n = 5) disclosed a mean standard uptake value of 2.4. Three tumors were composite pheochromocytoma-GN. Microsatellite instability study and immunohistochemical analysis of MSH2 protein in a patient carrying a MSH2 mutation showed normal MSH2 protein expression and low microsatellite instability, indicating that the adrenal GN was not related to the patient's MSH2 germline defect. CONCLUSIONS: We describe one of the largest series of adult adrenal GNs. Adrenal GNs may secrete testosterone or be part of a composite tumor with pheochromocytoma. The association of adrenal GN with MSH2 mutation seems to be a coincidental finding.

Updated recommendations from the Canadian National Consensus Meeting on HER2/neu testing in breast cancer.

Testing for HER2/neu in breast cancer at the time of primary diagnosis is now the standard of care. Accurate and standardized testing methods are of prime importance to ensure the proper classification of the patient's HER2/neu status. A meeting of pathologists from across Canada was convened to update the Canadian HER2/neu testing guidelines. This National HER2/neu Testing Committee reviewed the recently published American Society of Clinical Oncology/ College of American Pathologists (ASCO/CAP) guidelines for HER2/neu testing in breast cancer. The updated Canadian HER2/neu testing guidelines are based primarily on the ASCO/CAP guidelines, with some modifications. It is anticipated that widespread adoption of these guidelines will further improve the accuracy of HER2/neu testing in Canada.

Apoptosis in Barrett's oesophagus following antireflux surgery.

BACKGROUND: Intestinal metaplasia persists in Barrett's mucosa despite control of reflux. Tissue homeostasis is maintained by the balance between apoptosis and proliferation. There is an unexplained temporary increase in proliferation in patients with Barrett's mucosa after antireflux surgery, and the long-term effect of any therapy in altering this balance remains unclear. The aim of this study was to assess apoptosis in Barrett's oesophagus following antireflux surgery. METHODS: Apoptosis was evaluated in endoscopic biopsy specimens from 19 patients with Barrett's oesophagus 4 years after Collis-Nissen gastroplasty using an in situ terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labelling (TUNEL) method. RESULTS: Intestinal metaplasia had a lower apoptosis index than gastric metaplasia (0.27 versus 2.14 per cent; P < 0.001). After operation there was a steady increase of apoptosis in intestinal metaplasia over time (from 0.23 per cent before operation to 0.42 per cent within 2 years and to 0.59 per cent 4 years after operation; P = 0.015). Patients with persistent acid exposure did not show any increase in apoptosis in comparison with patients without acid exposure (0.41 versus 0.59 per cent; P = 0.91). CONCLUSION: Apoptosis is less in intestinal metaplasia than in gastric metaplasia, although there is an increase after antireflux surgery. Persistent acid reflux may predispose to malignancy.

Proliferative activity in Barrett's esophagus before and after antireflux surgery.

OBJECTIVE: To assess proliferation in the columnar-lined esophageal mucosa before and after antireflux surgery. SUMMARY BACKGROUND DATA: Intestinal metaplasia persists in Barrett's mucosa after reflux control. It remains at risk for uncontrolled cellular proliferation and adenocarcinoma formation. METHODS: Forty-five patients with Barrett's esophagus had a mean follow-up of 4 years after a Collis-Nissen gastroplasty. Proliferative activity was assayed immunohistochemically for Ki-67 expression in 73 preoperative and 176 postoperative biopsies. Correlation with manometric and 24-hour pH results was obtained. RESULTS: The Collis-Nissen gastroplasty restored the median lower esophageal sphincter gradient from 5.5 mmHg before surgery to 14.5 mmHg at 24 months and 12.9 mmHg at 48 months after surgery. The median esophageal acid exposure was reduced from 8% to 1% and 1% of recording time, respectively. The median Ki-67 labeling index increased from 28.5% before surgery to 36.1% at 12 to 23 months. It returned to preoperative level (26.9%) at 24 to 47 months. After surgery, abnormal intraesophageal acid exposure was documented in 12 patients but could not be correlated with sphincter pressure. After surgery, the pattern of proliferation in patients with acid exposure less than 4% in their esophagus showed significant differences when compared with the proliferation pattern of patients where abnormal intraesophageal acid exposure was recorded. New present dysplasia was observed only in patients with abnormal acid exposure. CONCLUSIONS: In Barrett's mucosa, from preoperative values, proliferation peaked early after surgery and then decreased to preoperative levels. Despite sphincter restoration and global reflux control, abnormal esophageal acid exposure persisted in 12 patients. Patients with abnormal esophageal acid exposure displayed more proliferation and more dysplasia.

The value of clonality in the diagnosis and follow-up of patients with cutaneous T-cell infiltrates.

The diagnosis of early stages of cutaneous T-cell lymphoma (CTCL) is often difficult, especially for lesions that are at the borderline between reactive and neoplastic skin T-cell infiltrates. T-cell monoclonality in these lesions is considered by some to be an important prognostic factor of neoplastic evolution, whereas others claim that clonality can also be found in benign skin infiltrates and is therefore of limited diagnostic value. To address this controversy, the authors analyzed retrospectively eight patients with lymphocytic skin lesions who progressed to CTCL, and three patients with recurrent T-cell lymphocytic infiltrates who had not developed CTCL. From a total of 65 biopsies of eight progressing patients, 32 were diagnosed as histologically malignant and 33 were diagnosed as benign or borderline. The authors found clonality by either polymerase chain reaction or Southern blot analysis in 88% of malignant and in 79% of nonmalignant lesions. None of the 37 biopsies of non-progressing patients was clonal. These results indicate strongly that the presence of monoclonality in T-cell skin infiltrates is related closely to the risk of developing CTCL. The value of clonality as a marker of malignancy is supported by the absence of T-cell clonal populations in all infiltrates from patients who had not progressed to lymphoma.

Molecular characterization of a pediatric pheochromocytoma with suspected bilateral disease.

An 11-year-old boy with hypertension was suspected of having bilateral adrenal pheochromocytomas and hyperplasia. Molecular analysis of specific tumor suppressor genes and oncogenes excluded the familial syndromes, von Hippel-Lindau (VHL) disease and multiple endocrine neoplasia (MEN) type 2A. Further evaluation identified a unilateral adrenal pheochromocytoma with a VHL heterozygous somatic mutation (G695A) and loss of the maternal allele at 11p15.5-11p14 exclusively in the tumor tissue. Both reverse-transcriptase polymerase chain reaction and immunohistochemistry confirmed increased expression of IGF2 within the tumoral tissue, relative to a normal control adrenal gland. These results ruled out familial syndromes and suggested that the VHL mutation and the loss of maternal allele on chromosome 11 could have contributed to tumor development.

Evaluation of the potential promoting effect of 60 Hz magnetic fields on N-ethyl-N-nitrosourea induced neurogenic tumors in female F344 rats.

The present study investigated the possible effect of 60 Hz magnetic fields (MFs) as promoters of neurogenic tumors initiated transplacentally by a chemical carcinogen, N-ethyl-N-nitrosourea (ENU). In a preliminary study, 5 mg of ENU was shown to induce 30 to 40% neurogenic tumors in F344 rats offspring after 420 days of observation. In the present study, 400 female rats were divided into eight different groups (50 animals/group) and exposed in utero (on day 18 of gestation) to a single intravenous dose of either Saline (Group I), or ENU, 5 mg/kg (Group II to VIII). Dams in group II were given no further treatment while dams in Groups III to VII were exposed to 5 different intensities of MFs forty eight hours later. Animals in group III were sham exposed (<0.02 microT) while groups IV to VII were exposed to 2, 20, 200, and 2000 microT, respectively. Dams in Group VIII were injected intraperitoneally with 12-O-tetradecanoylphrobol-13-acetate (TPA; 10 micrograms/kg) from day 19 until delivery, and then their female offspring continued to be injected every 15 days, starting at day 14 after birth until sacrifice (positive controls). Accordingly, this study included three different types of controls: Internal controls (Groups II and III) and positive control (Group VIII). Body weight, mortality and clinical observations were evaluated in all groups of animals during in-life exposure. Necropsy was performed on all exposed and control animals that died, were found moribund or sacrificed at termination of the study. Histopathological evaluation was done for all brains, spinal cords, cranial nerves, major organs (lungs, liver, spleen, kidneys, pituitary, thyroid and adrenals) and all gross lesions observed during necropsy. All clinical observations and pathological evaluations were conducted under "blinded" conditions. The findings from this ENU/MFs promotion study clearly demonstrate that, under our defined experimental conditions, exposure to 60 Hz linear (single axis) sinusoidal, continuous wave MFs had no effect on the survival of female F344 rats or on the number of animals bearing neurogenic tumors. These results suggest that MFs have no promoting effect on neurogenic tumors in the female F344 rats exposed transplacentally to ENU.

Asynchronous development of bilateral nodular adrenal hyperplasia in gastric inhibitory polypeptide-dependent cushing's syndrome.

Gastric inhibitory polypeptide (GIP)-dependent Cushing's syndrome has been reported to occur either in unilateral adrenal adenoma or in bilateral macronodular adrenal hyperplasia. A 33-yr-old woman with Cushing's syndrome was found to have two 2.5- to 3-cm nodules in the right adrenal on computed tomography scan; the left adrenal appeared normal except for the presence of a small 0.8 x 0.6-cm nodule. Uptake of iodocholesterol was limited to the right adrenal. Plasma morning cortisol was 279 nmol/L fasting and 991 nmol/L postprandially, and ACTH remained suppressed. Plasma cortisol increased after oral glucose (202%) or a lipid-rich meal (183%), but not after a protein-rich meal (95%) or iv glucose (93%); the response to oral glucose was blunted by pretreatment with 100 microg octreotide, sc. Plasma cortisol and GIP levels were positively correlated (r = 0.95; P = 0.0001); cortisol was stimulated by the administration of human GIP iv (225%), but not by GLP-1, insulin, TRH, GnRH, glucagon, arginine vasopressin, upright posture, or cisapride orally. A right adrenalectomy was performed; GIP receptor messenger ribonucleic acid was overexpressed in both adrenal nodules and in the adjacent cortex. Histopathology revealed diffuse macronodular adrenal hyperplasia without internodular atrophy. Three months after surgery, fasting plasma ACTH and cortisol were suppressed, but cortisol increased 3.6-fold after oral glucose, whereas ACTH remained suppressed; this was inhibited by octreotide pretreatment, suggesting that cortisol secretion by the left adrenal is also GIP dependent. We conclude that GIP-dependent nodular hyperplasia can progress in an asynchronous manner and that GIPR overexpression is an early event in this syndrome.

Genomic loci susceptible to replication errors in cancer cells.

Microsatellite instability due to a deficiency in DNA mismatch repair is characteristic of a replication error (RER) phenotype. This widespread genomic instability is well documented in hereditary non-polyposis colon cancer (HNPCC) as well as subsets of sporadic carcinomas. Features of the RER phenotype such as the early appearance in tumour development and better prognosis of RER+ colorectal tumours render its examination important for cancer patients. Recently, we identified four loci that were shown to be highly susceptible to RER in cancer cells. Here, we used these loci to detect the RER phenotype in sporadic carcinomas of colon, breast, lung, endometrium and ovary. Replication errors revealed by these four markers followed the same tumour specificity as observed in HNPCC patients. In particular, 24% (6/25) of colorectal, 33% (4/12) of endometrial and 17% (2/12) of ovarian cancers displayed the RER phenotype characterized by an increased allelic mobility, whereas none of the breast (n = 22) and the lung (n = 27) carcinomas were found to be unstable. Assaying RERs sensitive loci provides us with a useful diagnostic tool for HNPCC-like sporadic tumours.

Prophylactic thyroidectomy for medullary thyroid carcinoma in gene carriers of MEN2 syndrome.

BACKGROUND/PURPOSE: Although medullary thyroid carcinoma (MTC) can occur sporadically, in the pediatric population it is most often associated with the multiple endocrine neoplasia syndrome (MEN type 2). Traditional screening was based on evaluation of basal and stimulated serum calcitonin levels. The recent cloning of the MEN2 gene on the RET proto-oncogene of chromosome 10 now allows for testing of gene carrier status in individuals at risk who could benefit from prophylactic treatment. The current study was undertaken to determine the appropriate age for safe total prophylactic thyroidectomy. METHODS: Over a 16-year period, 12 patients with a family history of MEN2A and one with a MEN2B underwent total thyroidectomy and central neck dissection without parathyroid autotransplantation. Four patients (31%) were treated previously for Hirschsprung's disease. RESULTS: In seven patients (mean age, 11.8 years) undergoing biochemical screening for diagnosis, multifocal MTC and C cell hyperplasia (CCH) were found in all the resected specimens. Of six patients identified with genetic screening (mean age, 9.1 years), two had elevated stimulated calcitonin levels, one (age 14) had evidence of MTC, and one (age 6) had CCH. Four patients with normal calcitonin levels had no evidence of MTC (ages 6, 8, 10) but there was one occurrence of CCH (age 11). No permanent postoperative hypoparathyroidism or recurrent laryngeal nerve damage occurred in this series. With a mean follow-up of 4 years (range, 1 to 14 years), the overall disease-free survival is 100%. CONCLUSIONS: From this study the authors conclude that total thyroidectomy can be performed safely in children and should be the treatment of choice in patients with a family history of MEN2A carrying a germinal RET mutation even if the serum basal or stimulated serum calcitonin level is normal. Total thyroidectomy should be performed as early as 5 years of age before the occurrence of CCH or MTC.

Evaluation of the potential carcinogenicity of 60 Hz linear sinusoidal continuous-wave magnetic fields in Fischer F344 rats.

Electric and magnetic fields (EMFs) associated with the production, transmission, and use of electricity are ubiquitous in industrialized societies. These fields are predominantly of low frequency (50/60 Hz) and are generally of low intensity. Review of the epidemiological evidence shows that the association between exposure to EMFs and cancer is weak and inconsistent, and generally fails to show a dose-response relationship. Moreover, in view of the methodological problems of these epidemiological studies, animal and laboratory studies are urgently needed to determine whether EMFs could be initiators and/or promoters of cancers. The objective of the present study was to determine whether chronic exposure to 60 Hz linear (single axis) sinusoidal, continuous-wave magnetic fields (MFs) of different intensities might increase the risk of leukemia and solid tumor development in rodents born and raised under these fields. Five groups of 50 female F344 rats were exposed for 20 h/day to 60 Hz MFs at intensities of <0.02 (sham controls), 2, 20, 200, and 2000 microT. Full body exposure to the different fields was administered for 104 wk starting from the prenatal period (2 days before birth) and continuing during lactation and weaning until late adult life. Body weight, survival, and clinical observations were evaluated in all groups of animals during in-life exposure. Necropsy was performed on all exposed and control animals that died, were found moribund, or were killed at termination of the study. To preserve and demonstrate the absence of any experimental bias, all clinical observations and pathological evaluations were conducted under "blinded" conditions. Fifty organs and tissues were evaluated in each animal, with special attention to the incidence of mononuclear cell leukemia, brain tumors, and mammary tumors. The findings from this chronic carcinogenicity study demonstrate that, under our defined experimental conditions, exposure to 60 Hz linear (single axis) sinusoidal, continuous wave MFs did not affect animal survival, solid tumor, or mononuclear cell leukemia development in female F344 rats. No statistically significant, consistent, positive dose-related trends with the number of tumor-bearing animals per study group could be attributed to MF exposure.

Human immunodeficiency virus infection is a major risk factor for detection of human papillomavirus DNA in esophageal brushings.

The presence of human papillomavirus (HPV) DNA in esophageal brushings from human immunodeficiency virus (HIV)-seropositive hosts was investigated in a cross-sectional study. Oral and esophageal brushings from individuals scheduled for esophagogastroscopy (53 HIV-positive and 61 age-matched HIV-negative patients) were tested for the presence of HPV DNA by a consensus L1 polymerase chain reaction assay. HPV DNA was detected in esophageal brushings of 9 (17%) of the 53 HIV-seropositive patients and 0 of the 61 HIV-negative individuals. HPV-16 DNA was the most frequently detected. No proliferative mucosal lesion was noted in individuals with HPV-positive esophageal brushings. Cytological smears were done for 6 of the 9 patients with HPV-positive esophageal brushings, and epithelial atypia was recorded for 1. HIV infection and a history of genital herpes were strong independent predictors of HPV, suggesting that HPV is transmitted sexually in the esophagus.

Phototoxicity of some bromine-substituted rhodamine dyes: synthesis, photophysical properties and application as photosensitizers.

The synthesis of some bromine-substituted rhodamine derivatives viz., 4,5-dibromorhodamine methyl ester (dye 2) and 4,5-dibromorhodamine n-butyl ester (dye 3) are reported. These dyes were synthesized to promote a more efficient cancer cell photosensitizer for potential use in in vitro bone marrow purging in preparation for autologous bone marrow transplantation. Spectroscopic and photophysical characterization of these dyes together with rhodamine 123 (dye 1) are reported in water, methanol, ethanol and also in a microheterogeneous system, sodium dodecyl sulfate. The possible mechanism of photosensitization is characterized in terms of singlet oxygen efficiency of these dyes. Singlet oxygen quantum yields for bromine-substituted dyes are in the range of 0.3-0.5 depending on the solvent. For dye 1 no singlet oxygen production is found. The photodynamic actions of these dyes in different cell lines are tested. It was found that dye 2 and dye 3 are efficient photosensitizers and mediate eradication of K562, EM2, myeloid cell lines (CML) and the SMF-AI rhabdomyosarcoma line.

Steady state and time-resolved fluorescence properties of metastatic and non-metastatic malignant cells from different species.

Steady state and time-resolved fluorescence spectroscopy were employed to study the fluorescence from non-metastatic, metastatic and non-tumorigenic cell lines from different species. Excitations at 310 nm and 350 nm were used to monitor tryptophan and reduced nicotinamide adenine dinucleotide (NADH) fluorescence respectively. Subtle and consistent differences were observed between different categories of cell lines. It was found that the tryptophan to NADH fluorescence intensity ratio is higher in metastatic cell lines than in non-metastatic and normal cell lines. The fluorescence decay of the tryptophan residue in different cell lines was best described by triple exponential kinetics, whereas the NADH fluorescence decay was best described by mainly double and, in some cases, triple exponential kinetics. The average fluorescence lifetimes for tryptophan were in the range 2.5-3.7 ns. The average lifetime of NADH was lower (by a factor of approximately three) in metastatic cells than in non-metastatic cells and this finding is consistent for cell lines from different origins (rat or human). Correcting the fluorescence intensity for the average fluorescence lifetime of each species and for the volume of each cell line, it was shown that the concentrations of tryptophan and NADH are consistently higher in malignant metastatic cancer cells than in non-metastatic cells.

Cloning and identification of genes differentially expressed in metastatic and non-metastatic rat rhabdomyosarcoma cell lines.

The objective of this study was to identify genes involved in invasion and metastasis using a rat rhabdomyosarcoma model (SMF-A and RMS-B cell lines). The SMF-A cell line was established from a metastatic nodule of an induced rhabdomyosarcoma in syngeneic F344 rats. Two cell lines with defined metastatic potentials, SMF-Ai and SMF-Da, were cloned from the SMF-A line. The cell line SMF-Ai is tumorigenic, highly invasive and highly metastatic. On the other hand, the revertant line SMF-Da is less tumorigenic, non-invasive and non-metastatic. We have isolated from a SMF-Ai cDNA library eight cDNA clones which are differentially expressed by the metastatic SMF-Ai and the non-metastatic SMF-Da cell line using Northern blot analysis. Five of these clones, smf-4, smf-6, smf-41, smf-42 and smf-44, are overexpressed in the SMF-Da cell line and have homology with beta-2-microglobulin, lactate dehydrogenase, ribosomal protein L38, ribosomal protein S4 and acidic ribosomal phosphoprotein P1, respectively. The three other clones, smf-7, smf-40 and smf-61, are overexpressed in SMF-Ai. Clones smf-40 and smf-61 show significant homology with the human TB3-1 gene and the human fus gene respectively. The clone smf-7 has no significant homology with known sequences. We also analyzed the expression of these clones in other rat rhabdomyosarcoma cell lines (RMS-B and their clones) and in tumors obtained by injection of these cell lines into rats or nude mice. Smf-61 and smf-7 were the only clones with a differential expression pattern associated with the invasive or metastatic potential of all cell lines examined. A preliminary study of the expression of smf-7 and smf-61 in other cancer cell lines also showed mRNA expression in two human rhabdomyosarcomas and a human epidermoid carcinoma suggesting the existence of genes homologous to smf-7 and smf-61 clones in human cancers. Our findings suggest an association between the expression of smf-7 and smf-61 and invasive or metastatic potential of rhabdomyosarcoma cells.

Hyperplasia and tumours in lung, breast and other tissues in mice carrying a RAR beta 4-like transgene.

Transgenic mice were generated which express a truncated nuclear retinoic acid receptor beta (RAR beta), closely resembling the natural isoform RAR beta 4, under the control of the MMTV promoter. The transgene was expressed in salivary gland, testis, lung and mammary tissue in two different lines. At approximately 11-14 months virtually all the transgenic mice showed hyperplasia of the lung alveolar epithelium with an excess of type II pneumocytes. Hyperplasia of the mammary alveoli and terminal ducts was also seen in some females. Salivary glands and some sebaceous glands were hyperplastic in most male transgenic mice, but only rarely in females or in non-transgenics. Primary benign and malignant tumours were more numerous in transgenic mice than in controls, with a total of 23 in 43 mice versus two in 33 non-transgenic animals. Treatment with dexamethasone to increase transgene expression resulted in exaggerated versions of the above phenotypes. Overexpression of RAR beta 4 therefore appears to predispose various tissues to hyperplasia and neoplasia, and this by contrast to the RAR beta 2 isoform, which has tumour suppressor activity. A survey of ratios of RAR beta 4:RAR beta 2 expression in human lung tumour cell lines showed an increase compared with normal lung tissue, suggesting that RAR beta 4 may play a similar role in human tumorigenesis.