An experimental two-stage rat model of lung carcinoma initiated by radon exposure

Conference · Thu Dec 31 04:00:00 EST 1992

OSTI ID:44910

Poncy, J L ^[1]; Laroque, P; Fritsch, P; Monchaux, G; Masse, R ^[2]; Chameaud, J ^[3]

---

1. Commissariat a l`Energie Atomique, Bruyeres le Chatel (France)
2. Commissariat a l`Energie Atomique, Fontenay-Aux Roses (France)
3. COGEMA, Razes (France)

We present the results of a two-stage biological model of lung carcinogenesis in rats. The histogenesis of these tumors was examined, and DNA content of lung cells was measured by flow cytometry during the evolving neoplastic stage. Tumors were induced in rat lungs after radon inhalation (1600 WLM) followed by a promoter treatment; six intramuscular injections of 5,6-benzoflavone (25 mg/kg of body weight/injection) every 2 wk. Less than 3 mo after the first injection of benzoflavone, squamous cell carcinoma was observed in the lungs of all rats exposed to radon. The preneoplastic lesions gradually developed as follows: hyperplastic bronchiolar-type cells migrated to the alveoli from cells that proliferated in bronchioles and alveolar ducts; initial lesions were observed in almost all respiratory bronchioles. From some hyperplasias, epidermoid metaplasias arose distally, forming nodular epidermoid lesions in alveoli, which progressed to form squamous papilloma and, finally, epidermoid carcinomas. The histogenesis of these experimentally induced epidermoid carcinomas showed the bronchioloalveolar origin of the tumor. This factor must be considered when comparing these with human lesions; in humans, lung epidermoid carcinomas are thought to arise mainly in the first bronchial generations. The labeling index of pulmonary tissue after incorporation of {sup 3}H-thymidine by the cells was 0.2% in control rats. This index reached a value of 1 to 2% in the hyperplastic area of the bronchioles and 10 to 15% in epidermoid nodules and epidermoid tumors, respectively. DNA cytometric analysis was performed on cell suspensions obtained after enzymatic treatment of paraffin sections of lungs from rats sacrificed during different stags of neoplastic transformations. Data showed the early appearance of a triploid cell population that grew during the evolution of nodular epidermoid lesions to epidermoid carcinomas.

• OSTI ID: 44910
• Report Number(s): CONF-901010--Pt.2
• Country of Publication: United States
• Language: English

Related Subjects

55 BIOLOGY AND MEDICINE
BASIC STUDIES
56 BIOLOGY AND MEDICINE
APPLIED STUDIES
BIOLOGICAL MODELS
CARCINOGENESIS
CARCINOMAS
CELL FLOW SYSTEMS
LUNGS
RADIATION INDUCED MUTANTS
RADON
RATS
RESPIRATORY TRACT CELLS