PDGFRß promotes oncogenic progression via STAT3/STAT5 hyperactivation in anaplastic large cell lymphoma.

BACKGROUND: Anaplastic large cell lymphoma (ALCL) is an aggressive non-Hodgkin T cell lymphoma commonly driven by NPM-ALK. AP-1 transcription factors, cJUN and JUNb, act as downstream effectors of NPM-ALK and transcriptionally regulate PDGFRß. Blocking PDGFRß kinase activity with imatinib effectively reduces tumor burden and prolongs survival, although the downstream molecular mechanisms remain elusive. METHODS AND RESULTS: In a transgenic mouse model that mimics PDGFRß-driven human ALCL in vivo, we identify PDGFRß as a driver of aggressive tumor growth. Mechanistically, PDGFRß induces the pro-survival factor Bcl-xL and the growth-enhancing cytokine IL-10 via STAT5 activation. CRISPR/Cas9 deletion of both STAT5 gene products, STAT5A and STAT5B, results in the significant impairment of cell viability compared to deletion of STAT5A, STAT5B or STAT3 alone. Moreover, combined blockade of STAT3/5 activity with a selective SH2 domain inhibitor, AC-4-130, effectively obstructs tumor development in vivo. CONCLUSIONS: We therefore propose PDGFRß as a novel biomarker and introduce PDGFRß-STAT3/5 signaling as an important axis in aggressive ALCL. Furthermore, we suggest that inhibition of PDGFRß or STAT3/5 improve existing therapies for both previously untreated and relapsed/refractory ALK+ ALCL patients.

Expression of the tumor markers sialyl Lewis A, sialyl Lewis X, Lewis Y, Thomsen-Friedenreich antigen, galectin-1 and galectin-3 in human osteoblasts in vitro.

AIM: Lewis antigens and the Thomsen-Friedenreich (TF) antigen are complex glycan structures that modulate processes such as cell adhesion and proliferation and tumor metastasis. The aim of our study was to analyze the expression of sialyl Lewis A (sLeA), sialyl Lewis X (sLeX), Lewis Y (LeY), TF, galectin-1 (Gal-1) and galectin-3 (Gal-3) in human osteoblasts in vitro. MATERIALS AND METHODS: The expression of the tumor markers sLeA, sLeX, LeY, TF, Gal-1 and Gal-3 was studied by means of immunohistochemistry on cells grown on chamber slides (2D) and on paraffin sections three-dimensional scaffold-free cultures (3D). The results of the stainings were evaluated semiquantitatively with the immunoreactive scoring system (IRS). RESULTS: Analysis of sLeA expression in both types of culture, 2D and 3D showed no detectable staining. After 5 days, in the 2D culture, expression of sLeX was weak, but the 3D culture (after 56 weeks) displayed a strong expression. LeY was expressed very slightly in the 2D culture, however LeY was not detectable in the 3D culture. The TF epitope was identified in the 2D cell culture model. In the 3D model, however, TF was completely lacking. Gal-1 was expressed very strongly in 2D culture, but in the 3D culture was not detectable. In contrast, Gal-3 was expressed in 3D culture but not in 2D. CONCLUSION: Within this study, we present a systematic analysis of the expression of sLeA, sLeX, LeY, TF, Gal-1 and Gal-3 in human osteoblasts grown in 2D and in 3D scaffold-free cultures. Summarizing the results of our study, we suggest that Lewis antigens and Gal-1 and -3 might play an important role in cell-cell and cell-matrix interactions of osteoblastic cells.

Retinoid X receptor α and retinoids are key regulators in apoptosis of trophoblasts of patients with recurrent miscarriages.

The retinoid X receptor α (RXRα) is a nuclear hormone receptor that is able to bind other nuclear receptors in a heterodimeric complex, thereby activating gene transcription. Recently, we identified enhanced expression of RXRα in extravillous trophoblasts (EVT) and villous trophoblasts (VT) of miscarried placentas. In addition, an increased number of apoptotic EVT was present in miscarried placentas. In this study, on the basis of immunocytochemical analysis, western blots, and quantitative real-time reverse transcription PCR, we could demonstrate a reduced expression of RXRα in choriocarcinoma cell lines and in human VTs after stimulation with the retinoids 9-cis-retinoic acid and all-trans-retinoic acid and the prostaglandin 15-deoxy-Δ(12,14)-prostaglandin J(2). Furthermore, a simultaneous expression of RXRα and the apoptotic marker M30 CytoDEATH in EVT of miscarried placentas from the first trimester was shown. In EVT of control placentas from legal termination of pregnancies, no co-expression of RXRα and M30 could be detected. A likely conclusion is that RXRα plays an important role in the induction of apoptosis. Downregulation of RXRα, as observed in the tested choriocarcinoma cells and trophoblasts, might serve as a protection against apoptosis and miscarriage. In conclusion, RXRα represents a potential target in the treatment of recurrent miscarriages.

Glycodelin A and differentiation of first trimester trophoblast cells in vitro.

AIM: The glycoprotein, glycodelin A (GdA) is a main product of the maternal decidua in the first trimester of pregnancy and is secreted into the amniotic fluid. The purpose of this study was to investigate the effect of GdA on secretion and surface markers of isolated first trimester trophoblasts in vitro. METHODS: Cytotrophoblasts were prepared from human first trimester placentae and incubated with varying concentrations of GdA or transfected separately with the expression plasmid of GdA. Supernatants were assayed for human chorionic gonadotropin (hCG) protein concentrations. Expression of human placental lactogen (hPL), mucin 1 (MUC1) and the Thomsen-Friedenreich (TF) epitope was analysed in stimulated trophoblast cells and in unstimulated controls by immunocytochemistry. RESULTS: Glycodelin A induced a reduced expression of hPL compared with unstimulated controls. Expression of MUC1 was not affected by GdA. Freshly isolated trophoblast cells showed no TF expression but became positive for this antigen after 96 h of cultivation. GdA-stimulated trophoblast cells inhibited TF expression after 96 h of cultivation. GdA plasmids induced a significantly higher hCG production in transfected cells than in cells transfected with the empty plasmid. CONCLUSIONS: The results obtained in this study suggest that GdA is involved in the differentiation of trophoblast cells. The treatment of GdA plasmid transfected trophoblast cells stimulated hCG production in isolated trophoblast cells and inhibited hPL and TF expression, suggesting a functional link between hCG and GdA.

[Investigations on regulation of HCG by cortisol (prednisolon) in trophoblast cells in vitro]. / Untersuchungen zur Regulation von hCG durch Kortisol (Prednisolon) in der Trophoblastzelle in vitro.

OBJECTIVE: Trophoblast cells synthesize a variety of hormones, in which hCG plays a major role. On the strength of special enzymes they are capable of catalyzing the reaction cortisol <--> cortisone. In vitro experiments showed the influence on ACTH- and cortisol secretion by CRH, ACTH and prednisolon. In this study we describe the influence of cortisol (prednisolon) on hCG production of trophoblast cells in vitro. MATERIAL AND METHODS: Trophoblast cells were prepared from human term placentae by standard trypsin-DNAse dispersion of villous tissue followed by a percoll gradient centrifugation step. After adjusting the cell suspension to a defined cell concentration of 1 x 10 (6) cells/ml cells were cultivated. The addition of prednisolon followed every eight hours. The samples were collected after 24 hours for a total of 96 hours also from unstimulated cultures. Culture supernatants were assayed for hCG by enzyme-immunometric methods. RESULTS: The addition of prednisolon (50 microg/ml) stimulates the concentration of hCG in a time-depending manner. CONCLUSIONS: The trophoblast cell shows an increase in the concentration of hCG after stimulation with cortisol. For the first time an influence of cortisol (prednisolon) on hCG production could be demonstrated in cultured trophoblast cells.

Neuronal apoptosis following human brain injury.

Neuronal apoptosis has been investigated in paraffin-embedded brain tissue from 103 individuals who had sustained blunt head injury by use of the in situ nick translation (ISNT) technique. In order to provide reliable data for a forensic wound age estimation, a quantitative morphometric analysis was performed. Apoptotic neuronal cells could be detected in a cortical contusion with a wound age of 45 min at the earliest and in the majority of the cases with postinfliction intervals up to 2 weeks, numerous ISNT-positive cells were found adjacent to the traumatically injured area. The presented data indicate that neuronal apoptosis peaks at about 1 day and persists for at least 22 weeks after blunt head injury. The time-dependent occurrence of apoptotic cells can contribute to a forensic timing of cortical contusions and complements other immunohistochemical parameters, especially in the early postinfliction interval.

Mesenchymal differentiation and organ distribution of established human stromal cell lines in NOD/SCID mice.

Two human stromal cell lines were established previously from bone marrow-derived primary long-term cultures by immortalization using the SV40 large T antigen and cellular cloning. After irradiation, the fibroblast-like cell lines L87/4 and L88/5 support hematopoietic differentiation of allogeneic cord blood cells in vitro. The stromal cells do not express CD34 and CD50, but some adhesion molecules and integrins, such as CD44, CD54 and CD58. Their expression profiles on RNA and protein levels are suggestive of their osteogenic potency. The quality and quantity of osteocalcin and osteopontin protein expression depended on the culture conditions. Expression of the osteogenic markers increased over time in culture, especially in cells growing in clusters. The stromal cells also expressed collagens I and V, but did not show any expression of collagens II and III. The potentially osteoblastic stromal cells were transplanted into NOD/ SCID recipient mice by intravenous injection and were found in various mesenchymal organs up to 10 weeks after transplantation. Osteocalcin-positive human stromal cells could be detected in the bone marrow, thymus, liver, brain and gut of the recipient animals. In summary, there is evidence that human bone-marrow-derived stromal cells have to be considered mesenchymal progenitors, persistently expressing osteogenic markers in vitro and in vivo.

Shift of the distribution of age in patients with otosclerosis.

Morphological and biochemical investigations have shown evidence of an association between measles virus and otosclerosis. Epidemiological analysis of age and gender distributions in the 1960s and 1970s revealed a higher incidence of otosclerosis in women, the average age of onset of clinical disturbances and need for surgery being between 15 and 40 years. In the late 1960s and early 1970s a campaign to vaccinate children against measles was started in Germany. The aim of our study was to evaluate whether this campaign has had any influence on the distributions of the age and gender of patients affected by otosclerosis over the past 20 years. The study included patients suffering from clinical otosclerosis who had undergone stapedectomy between 1978 and 1999 and whose clinical data were complete (n = 1351). Statistical analysis during the recruitment period indicated a significant increase in the average age of the otosclerosis patients (p = 0.012). With regard to the gender distribution it was found that the increase of otosclerosis in women compared to men was statistically insignificant (p = 0.418). These data strongly support the hypothesis of a measles virus involvement in otosclerosis and may reflect a decreased incidence of otosclerosis in the generation of patients vaccinated against measles virus.

Immunohistochemical analysis of type-X-collagen expression in osteoarthritis of the hip joint.

Conflicting data have been reported on the spatial distribution of type X-collagen expression in osteoarthritis, and no concise data exist on a possible correlation between type X-collagen expression and clinical and radiological alterations. Well defined clinical and radiological data were compared with histopathological and immunohistochemical findings to investigate the expression of type-X collagen in osteoarthritis of the hip joint. Femoral heads were obtained in toto from 11 patients undergoing routine hip arthroplasty for femoral neck fractures (n = 3) or osteoarthritis (n = 8) and from 13 patients (age: 12 days to 69 years) without any evidence of hip-joint pathology. Whole coronal sections from the femoral head were decalcified for routine histology and immunohistochemical analysis with use of type-specific monoclonal antibodies to type-X collagen. Our results demonstrate that type-X collagen is consistently found in osteoarthritic cartilage and is absent from normal adult cartilage (including the region of calcified cartilage). Except for the occurrence of type-X collagen in the middle zone of articular cartilage in advanced stages of osteoarthritis, there is no specific change in the staining pattern or intensity for the collagen during osteoarthritis, particularly when the staining is related to clinical and radiological parameters. Hardly more than 20% of the extracellular matrix stained for type-X collagen; therefore, we suggest that, in most cases, this type of collagen may not play a direct biomechanical role in the weakening of osteoarthritic cartilage but rather may contribute indirectly to a disturbance of the disc biomechanics by altering matrix-molecule interaction. However, expression of type-X collagen may indicate a change in chondrocyte phenotype that consistently coincides with the formation of chondrocyte clusters, one of the first alterations in osteoarthritis visible on histologic examination.

In situ apoptotic and proliferation index in laryngeal squamous cell carcinomas.

The rate of cellular growth is mainly influenced by the balance between cell proliferation and cellular decay. Since to our knowledge, no study so far has analysed the rate of proliferation and apoptosis in the normal laryngeal mucosa and in invasive laryngeal carcinomas, we performed a morphological analysis on both parameters in biopsies from 30 patients with laryngeal carcinoma. We applied the TUNEL end labelling technique for the investigation of apoptosis and immunohistochemistry (Ki-67 antigen) for the determination of the cell proliferation. In our study we demonstrated that invasive tumour growth of the larynx coincides with an increase of both cellular proliferation and apoptosis. Both parameters, however, affected various tumour areas differently. While there was a preferential expression of the Ki-67 antigen at the tumour-stroma interface, apoptotic figures could be found randomly distributed in the tumour. This indicates that the replication of tumour cells and tumour cell decay are differently distributed and possibly independently regulated. Since we observed a particularly strong increase of cell proliferation at the tumour-stroma interface which outnumbered the corresponding rate of apoptosis by far, the enhanced cell proliferation at the tumour border seems to be a main factor for tumour growth. A statistical evaluation revealed significant correlation between the apoptotic index and the degree of tumour cell differentiation, indicating that a high rate of apoptosis coincides with a high level of tumour cell differentiation. There was, however, no statistically significant correlation between prognostic clinical parameters and the rate of apoptosis or that of proliferation.

Defective basement membrane in laryngeal carcinomas with heterogeneous loss of distinct components.

In this study, we evaluated immunohistochemically the composition of the tumor-associated epithelial basement membrane (BM) in a series of 66 laryngeal squamous cell carcinomas (SCC) and compared these results with those from 10 cases with laryngeal dysplasia and five cases with normal mucosa (controls). The major BM components collagen IV and VII, laminin-1, perlecan (heparan sulfate proteoglycan), and fibronectin were evaluated. The extent of the retained BM material was quantified by semiautomated morphometry. A subsequent statistical analysis correlated the immunohistochemical findings with the histopathologically evaluated degree of tumor cell differentiation. In our series, we observed a distinct correlation between the degree of tumor cell differentiation and the amount of retained BM material. The loss of BM affected the various components differently, with a more extensive loss of collagen VII even in highly differentiated tumors and a progressive loss of collagen IV immunostaining with decreasing tumor cell differentiation. With respect to the other BM components, a stepwise loss of BM material also was seen with decreasing degree of the tumor cell differentiation. This loss, however was not at a statistically significant level, so these parameters did not show further statistically relevant data. In dysplastic lesions (regardless of the degree of dysplasia), focal BM disruptions were seen that affected the various BM components to a very similar extent. Our observations provide evidence that laryngeal carcinomas show a progressive loss of BM material along with decreasing tumor cell differentiation. This loss of BM, however, affects the various BM components differently. This indicates a dysregulation of the BM, either induced by uncoordinated neosynthesis or selectively enhanced degradation by proteases or both. Finally, the BM analysis may provide information on the biological course of the tumors. The loss of collagen VII may serve as a marker for "early" invasive tumor growth, whereas the amount of collagen IV provides significant information on the loss of tumor cell differentiation.

Prognostic aspects of the loss of epithelial basement membrane components in preinvasive and invasive laryngeal carcinomas.

The integrity of the epithelial basement membrane (BM) is an essential criterion or the biological behaviour of tumors. Previous studies on various types of carcinomas have demonstrated a good correlation between the amount of retained BM and the course of tumor growth. We therefore evaluated the prognostic significance of the tumor BM in laryngeal carcinomas. In this study, we analyzed 66 cases of laryngeal carcinomas using immunohistochemistry for the visualization of the major BM components collagen IV and VII, laminin-1, heparan sulfate proteoglycan (HSPG, perlecan) and fibronectin. The extent of retained BM-material was quantified morphometrically. A subsequent statistical analysis correlated the immunohistochemical findings with clinical and routine histological parameters, such as the mode of tumor infiltration. All carcinomas showed a defective epithelial BM. In addition, we observed a correlation between the degree of tumor cell-differentiation and the amount of BM material retained. The loss of BM, however, affected the various components differently with an "early" loss of collagen VII. In non-infiltrative dysplastic lesions focal BM disruptions were seen which affected the various BM components very similarly. When we statistically analyzed the correlation between the BM staining pattern and prognostically relevant parameters, collagen VII represented a marker for "early" stroma invasion. It also positively correlated with tumor size/stage, presence of lymph node metastasis and the recurrence of tumor growth. The collagen IV expression was positively correlated with the degree of tumor cell differentiation. The other parameters did not show further prognostically relevant data. Our observations provide significant information on the biological course of the disease. Thus, collagen VII may be a marker for "early" invasive tumor growth, as well as for lymphatic metastasis and local tumor recurrence, while the amount of collagen IV correlates with the tumor cell differentiation.

Immunolocalization of major interstitial collagen types in human lumbar intervertebral discs of various ages.

We used complete transverse sections through 65 samples of human lumbar intervertebral discs for immunolocalization of the major interstitial collagen types I, II, III, V, VI and IX. The samples were selected from 47 patients ranging in age from 0 (fetuses) to 86 years. The results were compared with the histological findings in disc tissue degeneration and/or reparative alterations as indicated by tear and cleft formation, chondrocyte proliferation, mucous degeneration, granular matrix changes and fibrocartilage fibrillation. We observed a typical pattern for each antibody and each anatomical structure, with, however, remarkable inter- and intraindividual variability, which could be monitored only by use of the complete transverse sections. Accordingly, collagen I was seen in the normal annulus fibrosus and in the degeneratively altered nucleus pulposus, but not within the end-plate, regardless of degenerative changes. Collagens II and IX were found in the normal nucleus pulposus, the inner annulus fibrosus and the end-plate. The collagen II (and IX) staining seemed to be enhanced in areas of minor degenerative lesions, but reduced in advanced lesions and in the degenerated end-plate. Collagens III and VI were significantly increased in areas of minor to advanced degeneration in all anatomical settings, while collagen V showed only minor changes in its staining pattern. In general, histological signs of tissue degeneration coincided with significant quantitative, but also with certain qualitative, changes in the composition of the collagenous disc matrix. These observations indicate the association of degenerative and/or reparative alterations of the intervertebral disc and changes in the collagenous matrix, but document the variability in the extent of the abnormalities observed.

Congenital alveolar capillary dysplasia: rare cause of persistent pulmonary hypertension.

We report on a rare case of fatal congenital alveolar capillary dysplasia. The newborn boy of a 37 weeks' normal gestation suffered from persistent pulmonary hypertension without any cardiovascular malformation and died at the age of 4 weeks despite intensive treatment. The autopsy tissue was examined histologically, immunohistochemically, and ultrastructurally. Moreover, a three-dimensional tissue reconstruction based on serial sections was performed comparing the affected lung with normal lung tissue. We observed a unique pattern of pulmonary dysplasia: An extreme decrease of capillaries was localized centrally within thickened intra-acinar septa instead of capillaries intensely neighboring pneumocytes; ectatic veins normally running in the interlobular septa were found to accompany intralobular bronchovascular bundles, denying a clear distinction between pulmonary and bronchial veins; small muscular pulmonary arteries extended to the precapillary level and type 2 pneumocytes exceeded by far the type 1 pneumocytes, inverting the normal ratio. In summary, alveolar capillary dysplasia is assumed to be a primary capillary disorder of unknown origin, which possibly involves the regular differentiation of pneumocytes, according to the close alveolocapillary relationship during pulmonary ontogenesis. We consider the venous alterations as being part of the dysplasia, whereas the arterial phenomena might occur secondarily. Recent reports on affected siblings suggest a genetic component of pathogenesis.

Detection of cell death in human skin wounds of various ages by an in situ end labeling of nuclear DNA fragments.

The time-dependent appearance of signs of cell death was investigated in human skin wounds using in situ end labeling of DNA fragments (ISEL). In the dermal layer an average of not more than 0.3 positively stained fibroblastic cells/0.01 cm x 0.01 cm was found up to a postinfliction interval of approximately 6 h. Average numbers exceeding 1 positive cell/0.01 cm x 0.01 cm were first detectable in a skin wound after 24 h. Therefore, average numbers greater than 1 labeled cell/ 0.01 cm x 0.01 cm indicate a postinfliction interval of approximately 1 day. An increase in the average number of positively stained cells occurred with increasing wound age. Values exceeding 3 cells/0.01 cm x 0.01 cm were first detectable 19 days after wound infliction. Accordingly, values of more than 3 labeled cells indicate a postinfliction interval of approximately 3 weeks or more. Since low numbers of labeled fibroblastic cells or even negative results were found in wounds of advanced age, only positive results provide information which can be useful for a forensic age estimation of human skin wounds.

Immunolocalization of type X collagen in human lumbar intervertebral discs during ageing and degeneration.

Type X collagen has so far not been reported to occur in human intervertebral discs. The objective of this study was therefore to investigate the occurrence of type X collagen in human lumbar intervertebral discs during ageing and degeneration. Ninety intervertebral discs with adjacent endplates were excised in toto from individuals (0-86 years) without known spinal disease and were processed for routine decalcified histology. Appropriate slices of each disc were processed for immunohistochemistry using a type-specific, monoclonal antibody raised against human type X collagen. Each intervertebral disc was examined for macroscopic and histomorphological features of disc degeneration. Immunohistochemically, a positive specific type X staining was observed in the hypertrophic zone of the growth plate and only in the interstitial matrix of juvenile (<2 years) nucleus pulposus. In adult discs, type X collagen could be localized in conjunction with advanced disc degeneration and first occurred in the disc matrix (i.e., pericellular region) of a 47-year-old specimen. Positive type X staining of the disc matrix was more frequently found in senile (>70 years) discs with end stages of disc degeneration. This study provides the first evidence for the occurrence of type X collagen in human lumbar intervertebral discs and it appears that type X collagen is re-expressed in late stages of disc degeneration.

Gene expression and protein deposition of major basement membrane components and TGF-beta 1 in human breast cancer.

In the present study we used immunohistochemistry and in-situ hybridization for the localization of major basement membrane (BM) components and their mRNA, respectively, in order to determine the extent of BM production and deposition in normal mammary tissue as well as in invasive mamma carcinomas. While normal mammary tissue showed an intact epithelial BM, as evidenced by a continuous linear staining for collagen i.v., laminin, heparan sulfate proteoglycan (perlecan) and fibronectin, this staining was widely lost in the invasive carcinomas. Non-invasive intraductal areas of the carcinomas (carcinoma-in-situ) revealed focal fragmentation and duplication of the epithelial BM. Using in-situ hybridization, we observed only focally positive mRNA-expression for collagen i.v.-, perlecan- and fibronectin-mRNA in normal glands, while mRNA-signals were significantly enhanced in one case of fibroadenoma and particularly in invasive and non-invasive carcinomas, regardless of the degree of tumor cell differentiation. In these instances both tumor and stroma cells were positively labelled. In addition, we could demonstrate a significant increase in the level of TGF-beta 1-mRNA--as the most active cytokine for the induction of matrix component production--by carcinoma cells and to lesser extent by stroma cells. The discrepancy between significantly enhanced mRNA-synthesis and loss in protein deposition points either to an upregulated activity of matrix degrading proteinases (matrix-metalloproteinases) or a posttranslational block of protein synthesis or both.

Distribution of basement membrane components in normal adipose tissue and in benign and malignant tumors of lipomatous origin.

Normal adipose tissue as well as 13 benign and 17 malignant lipomatous tumors (lipomas, hibernomas, lipoblastomas, and liposarcomas) were immunohistochemically analyzed for their expression of the basement membrane components collagen IV, laminin, heparan sulfate proteoglycan, and fibronectin. Monovacuolar cells in normal white fat tissue and in lipomas generally exhibited a distinctive pericellular basement membrane composed of collagen IV and laminin, whereas heparan sulfate proteoglycan and fibronectin were almost completely missing. In brown fat tissue and hibernomas the characteristic multivacuolated cells differed from the monovacuolated white fat cells by the additional content of heparan sulfate proteoglycan and fibronectin and the more intensive staining for the other components tested. In contrast, multi-/monovacuolated cells in lipoblastomas exhibited no characteristic immunohistochemical feature because they reacted irregularly and only faintly for collagen IV, laminin, and heparan sulfate proteoglycan. Spindle cell areas in benign lipomatous tumors displayed more fibronectin than laminin and heparan sulfate proteoglycan indicating a "preadipose" fibroblast-like cellular differentiation. In liposarcomas, only well-differentiated lipoma-like neoplasms revealed a basement membrane pattern resembling that of white fat tissue. Otherwise, in nonlipoma-like liposarcomas, a marked decrease particularly of collagen IV staining was evident. Poorly differentiated liposarcomas mostly failed to express any of the basement membrane components, but showed a relative increase of fibronectin. Our results provide evidence that the staining pattern of basement membrane components parallels the histogenetic derivation of benign lipomatous tumors from either brown or white adipose tissue and, additionally, may reflect such a derivation in liposarcomas.

Increased expression of type VI collagen in lung fibrosis.

Pulmonary fibrosis is characterized by disturbances of extracellular matrix protein deposition resulting from fibroblast activation and proliferation. Collagen VI, forming microfibrillar meshworks separate from major fibrillar systems, is thought to serve as an anchoring element between collagen I/III fibrils and basement membranes and as a cell binding substrate. We report on the expression of collagen VI in normal and in fibrotic lungs. Collagen VI is present in vascular and bronchial walls and in the interstitial space of normal lungs. Its turnover is too low to generate a mRNA signal by in situ hybridization. Collagen VI expression is increased in lung fibrosis, and its degree appears independent of the etiology of fibrosis. There was no evidence for differential regulation of gene expression for the alpha 1(VI) and alpha 3(VI) constitutive peptide chains of collagen VI. Collagen VI mRNA is expressed by fibroblasts, mostly with myofibroblast characteristics. Collagen VI was coexpressed with collagen III rather than collagen I in idiopathic bronchiolitis obliterans with organizing pneumonia, acute interstitial pneumonitis of the Hamman-Rich type, and bleomycin-induced fibrosis, but collagen VI overlapped with collagen types I and III in idiopathic pulmonary fibrosis. These coexpression data suggest that collagen VI expression may be an early rather than a late phenomenon in pulmonary fibrosis.