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H D Menssen

Publications and source records attributed to H D Menssen.

24 records · Page 2Linked to original sources
PubMed1991

Constitutive expression of multiple growth factor genes by melanoma cells but not normal melanocytes.

In a panel of metastatic melanoma cell lines we found steady-state mRNA transcripts for multiple growth factors including basic fibroblast growth factor (bFGF), platelet-derived growth factor (PDGF)-A, PDGF-B, transforming growth factor (TGF)- beta 1, TGF- alpha, melanoma growth-stimulating activity (MGSA), interleukin (IL)-1 alpha, and IL-1 beta but not insulin-like growth factor (IGF)-1 or IGF-2. Expression of growth factor genes was constitutive because prior to RNA extraction melanoma cells were maintained in a chemically defined culture medium free of exogenous growth factors. Each of four cell lines had an individual pattern of expression of either two, four, five, or seven growth factors; however, all cell lines shared expression of the bFGF gene. Two strains of normal melanocytes expressed TGF- beta 1 but not bFGF, PDGF, TGF- alpha , or MGSA mRNA at detectable levels. We tested growth-modulatory effects of the growth factors most frequently expressed by melanoma cells (bFGF, TGF- alpha, TGF- beta, PDGF). None of these stimulated melanoma cell growth consistently, whereas exogenous, acid-activated TGF- beta inhibited melanoma growth at concentrations greater than 10 ng/ml, suggesting that bioactive TGF- beta may represent a physiologic growth inhibitor. Neither neutralizing antisera to PDGF or TGF- alpha nor a monoclonal antibody to the epidermal growth factor (EGF)-receptor inhibited melanoma cell growth. Our results indicate that multiple growth factors are expressed simultaneously and constitutively by melanoma cells but not normal melanocytes in culture. Expression of bFGF is a common feature underscoring the significance of bFGF as an autocrine factor for melanoma cells as described earlier. Secreted PDGF and TGF- alpha are apparently not involved in or not essential for autocrine growth stimulation of melanoma cells.

Blotting, Northern↗
PubMed1987

Rapid dissociation of adherent human tumor cells by ultrasound.

Cultured human melanoma and gastrointestinal carcinoma cells were detached from substrate and further dissociated by placing the culture vessel into a water-filled ultrasonic cleaner (43 kHz) and sonicating it for 10-50 s. Plating efficiency and long-term growth of three melanoma cell lines were similar after ultrasound or trypsin detachment. Binding of monoclonal antibodies that define normal and tumor-associated antigens on melanoma and colorectal carcinoma cells was not affected by ultrasound in 21 out of 23 cases. The 40 kDa colorectal carcinoma-associated antigen defined by monoclonal antibody CO 17-1A was more highly expressed after ultrasonication than trypsinization. The antigen defined by antibody CO 44.1 on these cells was more sensitive to sonication. This method represents a rapid, effective and gentle alternative to trypsin detachment of cultured cells, especially when repeated cell washing or centrifugation steps are required.

Antibodies, Monoclonal↗
PubMed1987

Metastatic but not primary melanoma cell lines grow in vitro independently of exogenous growth factors.

Five out of 6 cell lines derived from metastatic melanoma lesions grew in a chemically defined base medium consisting of a mixture of calcium-supplemented MCDB 153 and L 15 media in the absence of any polypeptide growth factors. In contrast, under these conditions no growth was seen in any of 5 primary melanoma cell lines tested, including 2 cell lines from patients whose metastatic cells proliferated well in base medium. Growth stimulation of all 11 melanoma cell lines by epidermal growth factor (EGF), transferrin, insulin, and insulin-like growth factor (IGF)-1 alone and in various combinations was studied. Insulin represented the strongest single growth factor for primary and metastatic melanoma cell lines. The metastatic cell lines remained growth-responsive to EGF, insulin and transferrin and responded more vigorously to these exogenously provided mitogens than the primary cell lines. No synergistic or additive growth effects of insulin, transferrin, or EGF for primary and metastatic cell lines were observed. Cross-linking studies with 125I-IGF-1 demonstrate surface expression of the type-I IGF receptor on melanoma cells. Growth stimulation by insulin and IGF-1 was inhibited by adding to the culture medium a monoclonal antibody to the type-I IGF receptor. Our studies indicate that IGF-1 and insulin are major growth factors for melanoma cells and act via the type-I IGF receptor.

Cell Division↗
PubMed1986

A quantitative electron microscopic study of the effect of glucocorticoids in vivo on the early postnatal differentiation of paraneuronal cells in the carotid body and the adrenal medulla of the rat.

The postnatal differentiation of carotid body chief cells and endocrine adrenal medullary cells was comparatively examined during ontogenesis and in rats which were treated with dexamethasone for 7 days after birth. Ultrastructure and innervation of carotid body chief cells are mature in neonates according to the functional requirements of chemoreception. By the end of the first postnatal week, only an increase in number of dense core vesicles can be noticed, the concentration of which then will reach the adult level. Under the effect of dexamethasone most of the heterochromatin is transformed into finely dispersed euchromatin within the nuclei of carotid body chief cells. In the cytoplasm, the Golgi apparatus becomes larger and the granular endoplasmic reticulum hypertrophic. The number of catecholamines storing dense core vesicles increases considerably. The innervation density remains constant. In contrast to the carotid body chief cells, the adrenal medullary cells have not reached their definitive maturity at the time of birth. Besides phenotypes of adrenaline-cells, noradrenaline-cells and small granules containing cells, pheochromoblasts and intermediary cells can be seen as well. Their cytoplasm is sparse, the concentration of dense core vesicles and the innervation density very low. After 8 days of postnatal ontogenesis, pheochromoblasts and intermediary cells are no longer present in the adrenal medulla. In adrenaline-cells and noradrenaline-cells, important processes of growth can be noticed, the cytoplasm has grown in extent, the number of dense core vesicles doubled and the innervation density of single cells triplicated. Only the few small granules containing cells remain small. Under the effect of dexamethasone also in the nuclei of chromaffin cells a transformation of heterochromatin into euchromatin occurs. The increase in number of dense core vesicles is relatively lower than in carotid body chief cells. The significant growth of innervation density during the first postnatal week was inhibited. Our observations suggest that dexamethasone stimulates the synthesis of catecholamines in adrenal medullary cells of newborn rats less pronouncedly than in carotid body chief cells. This could be attributed to the inhibited formation of synapses of growing chromaffin cells and to the in vivo active endocrine counter-regulation.

Adrenal Medulla↗
PubMedDate not supplied

Tumor progression in the human melanocytic system.

The isolation and routine tissue culture of melanocytic cells from normal skin, precursor nevi, primary and metastatic melanomas has allowed the experimental study of different stages of tumor progression. Characteristic differences between cultured normal melanocytes and highly malignant metastatic melanoma cells were: 1) limited life span for normal melanocytes and non-malignant nevus cells versus infinite growth for malignant melanoma cells; 2) inability to grow anchorage-independently versus high colony forming-efficiency in soft agar; 3) non-tumorigenicity versus tumorigenicity in athymic nude mice; 4) dependence on exogenous growth factors and other mitogens versus autonomous growth in protein-free medium; 5) expression of melanocyte-associated antigens versus expression of melanoma-associated antigens; and 6) diploid karyotype versus non-random chromosomal abnormalities. The only major distinction found between advanced primary and metastatic melanomas was that only metastatic melanoma cells proliferated continuously in the absence of growth factors or other proteins. However, advanced primary melanoma cells could be clearly distinguished from dysplastic nevus cells by their growth behavior and growth factor requirements. Only limited information is available on the biologic, genetic, immunologic and molecular properties of dysplastic nevus cells and early (radial growth phase) primary melanoma cells but these cells appear to differ markedly from advanced primary and metastatic cells. The availability of cells from sequential steps of tumor progression in the human melanocytic system offers a unique experimental model for the study of malignant transformation.

Animals↗