Detection of transforming growth factor-alpha messenger RNA in normal and chemically transformed hamster oral epithelium by in situ hybridization.
We have recently demonstrated the consistent detection of transforming growth factor alpha (TGF-alpha) in chemically transformed hamster oral tumors. By Northern blot analysis, no TGF-alpha mRNA can be detected in normal cheek pouch mucosa. The consistent expression of TGF-alpha associated with the malignant transformation in the well-defined hamster oral cancer model prompted us to hypothesize that the aberrant expression of this important cellular gene could be related to a specific stage of epithelial alteration. In situ hybridization was used to test this hypothesis. We now report that by in situ hybridization we can detect TGF-alpha mRNA in normal hamster oral epithelium and also at all stages of transformation. In all epithelium, labeling of TGF-alpha mRNA in the basal layer is more pronounced than that observed in the spinous and squamous layers. There is a significant increase of TGF-alpha mRNA labeling early in 7,12-dimethylbenz(a)anathracene-induced oral carcinogenesis. This increase is associated with morphological changes of epithelial hyperplasia or dysplasia. Although lesions exhibiting full-thickness epithelial dysplasia (carcinoma in situ) showed more labeling of TGF-alpha mRNA than do areas of lesser dysplasia, the transition to full-fledged papillary or invasive squamous cell carcinoma is not associated with further elevations of TGF-alpha expression.
Chang
L C
LC
Department of Oral Medicine and Oral Pathology, Harvard School of Dental Medicine, Boston, Massachusetts 02115.
Chou
M Y
MY
Chow
P
P
Matossian
K
K
McBride
J
J
Tao
C A
CA
Gallagher
G T
GT
Wong
D T
DT
D015127:9,10-Dimethyl-1,2-benzanthracene; D000818:Animals; D002278:Carcinoma in Situ / Q000139:chemically induced / Q000235:genetics; D002294:Carcinoma, Squamous Cell / Q000139:chemically induced / Q000235:genetics; D002471:Cell Transformation, Neoplastic / Q000235:genetics*; D006224:Cricetinae; D015972:Gene Expression Regulation, Neoplastic; D009061:Mouth Mucosa / Q000502:physiology*; D009693:Nucleic Acid Hybridization; D012333:RNA, Messenger / Q000235:genetics*; D012334:RNA, Neoplasm / Q000235:genetics; D013997:Time Factors; D015291:Transforming Growth Factors / Q000235:genetics*
D012333:RNA, Messenger; D012334:RNA, Neoplasm; D015127:9,10-Dimethyl-1,2-benzanthracene; D015291:Transforming Growth Factors