Three types of human lung tumour cell lines can be distinguished according to surface expression of endogenous urokinase and their capacity to bind exogenous urokinase

Our plain-English summary of Three types of human lung tumour cell lines can be distinguished according to surface expression of endogenous urokinase and their capacity to bind exogenous urokinase, by R. Schwartz-Albiez, H.H. Heidtmann, D. Wolf, et al (British Journal of Cancer, 1992).

The study

• Authors: R. Schwartz-Albiez, H.H. Heidtmann, D. Wolf, V. Schirrmacher, G. Moldenhauer
• Journal: British Journal of Cancer
• Published: 1992;65(1):51-7
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

This study evaluates the cell surface expression of urokinase-type plasminogen activator (u-PA) and the capacity to bind exogenous urokinase as possible parameters for the distinction of various types of human lung tumours. Twelve different tumour cell lines including four small cell carcinoma, two large cell carcinoma, three squamous cell carcinoma, one adenocarcinoma and two mesothelioma cell lines of lung origin were investigated. Surface expression of endogenous u-PA was determined in a cellular radioimmunoassay (CRIA) using the u-PA-specific monoclonal antibody 98/6. To estimate additional u-PA binding capacity, exogenous two-chain, 54 kDa u-PA was employed in the CRIA. The influence of phorbol ester (PMA) treatment on expression and binding of these molecules was studied. Three different groups of lung tumour cell lines could be distinguished according to their expression of u-PA and u-PA-binding ability: (i) non small cell lung carcinoma (NSCLC) cell lines of squamous cell carcinoma/adenocarcinoma origin expressed small amounts of u-PA and bound little u-PA. Large cell carcinoma cell lines expressed high amounts of u-PA and bound large amounts of u-PA. In general, expression of u-PA and u-PA binding was enhanced after PMA treatment. (ii) Mesothelioma cell lines did not express u-PA, but were able to bind u-PA. (iii) Small cell carcinoma (SCLC) lines were devoid of surface-expressed u-PA and could not bind u-PA, both under untreated and PMA-treated conditions. It could thus be demonstrated that these three groups of lung tumour cell lines differ in their ability to express u-PA and to bind external u-PA. This may reflect the different in vivo growth behaviour and origin of the respective tumour groups.

In plain English

This was a laboratory study by researchers in Germany. It tested twelve human lung tumour cell lines grown in culture, including two mesothelioma cell lines of lung origin (MSTO-211H and CH3LC). It did not study asbestos or patients. The authors measured whether the cells carried an enzyme, urokinase-type plasminogen activator (u-PA), on their surface, and whether they could bind u-PA added from outside. They tested cells with and without the chemical stimulant phorbol ester (PMA). The lines fell into three groups. Squamous cell and adenocarcinoma lines showed weak surface u-PA, and the two large cell carcinoma lines showed much more. Both of these types also bound added u-PA. The two mesothelioma lines showed no surface u-PA but bound added u-PA in amounts comparable to the squamous cell lines. In one of them, CH3LC, the authors estimated 72,300 occupied binding sites per cell without PMA and 196,000 with PMA. Small cell carcinoma lines neither showed nor bound u-PA. The authors concluded that the groups differ in these properties, which may reflect differences in tumour growth and origin. They said the findings still need testing in actual tumour samples.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory (in vitro) study of human tumour cell lines, using a cellular radioimmunoassay (CRIA) with a u-PA-specific monoclonal antibody (98/6) and radiolabelled u-PA
• Who was studied: Twelve human lung tumour cell lines: four small cell carcinoma, two large cell carcinoma, three squamous cell carcinoma, one adenocarcinoma and two mesothelioma cell lines (MSTO-211H and CH3LC) of lung origin. No human subjects.
• Exposure: No asbestos exposure was studied. The cell lines were tested with and without phorbol ester (PMA) treatment for 3 days, and were incubated with added (exogenous) two-chain, 54 kDa u-PA to measure binding capacity.
• Main results:
  • Squamous cell carcinoma and adenocarcinoma cell lines showed weak surface u-PA (3-5 fold background binding), which increased after PMA treatment.
  • The two large cell carcinoma cell lines showed much stronger surface u-PA than the squamous cell carcinoma lines, and this was also enhanced by PMA.
  • All small cell carcinoma cell lines and both mesothelioma cell lines were negative for surface u-PA.
  • Both mesothelioma cell lines bound added u-PA in amounts comparable to the squamous cell carcinoma lines, and PMA enhanced this binding. CH3LC bound 28,000 ± 1,020 cpm untreated and 54,830 ± 3,690 cpm after PMA.
  • In mesothelioma line CH3LC, pre-loaded with u-PA, Scatchard analysis estimated 72,300 occupied binding sites per cell untreated and 196,000 per cell after PMA treatment.
  • The authors regarded all small cell carcinoma cell lines as negative for u-PA binding sites, despite low binding values in two lines.
  • In the two large cell carcinoma lines, binding of added u-PA was reduced after PMA treatment, an exception to the general pattern.
  • Added u-PA could not be displaced once bound. The authors tentatively concluded that it forms an irreversible, presumably covalent, complex with an as yet unknown surface protein.
• The authors' conclusion: The authors concluded that the three groups of lung tumour cell lines differ in their ability to express u-PA and to bind external u-PA, and that this may reflect the different growth behaviour and origin of the tumour groups. They also suggested that u-PA binding by mesothelioma cell lines may add a new parameter for telling these lung tumours apart.
• Limitations the authors state:
  • The authors stated that the findings, from cultured cell lines, need to be transferred to investigation of native tumour samples to understand interactions in the body.
  • The authors stated that the function of u-PA binding sites on tumour cells that do not make components of this enzyme system remains unclear.
  • Direct measurement of u-PA binding sites using radiolabelled u-PA did not give a reliable linear Scatchard plot.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer.

Medical terms in this study, explained in our Lexicon: Carcinoma, Squamous Cell Carcinoma, Adenocarcinoma, Mesothelioma, Monoclonal Antibody.

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