Comparison of c-myc expression in normal human bronchial epithelial cells and lung cancer cell lines using a quantitative fluorescence-based reverse transcriptase polymerase chain reaction method
Wr. Fields et al., Comparison of c-myc expression in normal human bronchial epithelial cells and lung cancer cell lines using a quantitative fluorescence-based reverse transcriptase polymerase chain reaction method, TOX METHOD, 9(3), 1999, pp. 173-188
Mutations, either heritable or induced, can modulate the expression of onco
genes and/or tumor suppressor genes and thereby alter the biology of the af
fected cells. Overexpression of the c-myc oncogene appears to contribute to
the development of small cell lung cancer, and has been used as an indicat
or of poor prognosis for this tumor type. However neither the variability o
f c-myc expression in noncancerous human lung tissue retrieved from differe
nt donors nor the level of c-myc expression in various lung tu:mor types ha
s been adequately studied. The authors have quantified and compared the exp
ression of c-myc in normal human bronchial epithelial (NHBE) cells from sev
eral noncancerous lungs and in transformed human lung cell lines. c-myc mRN
A levels were determined through the annealing of a gene-specific probe to
a target cDNA copy of the mRNA. The fluorescence signal liberated by the 5'
-3' exonuclease-induced release of the re,porter dye from the annealed prob
e during the extension cycle of polymerase chain reaction (PCR) was quantif
ied spectrophotometrically. While NHBE cells from four donors expressed com
parable levels of c-myc mRNA, the c-myc mRNA levels in large cell lung carc
inoma (LCLC) and small cell lung carcinoma (SCLC) cell lines were 2.4- and
5.0-fold greater than in NHBE cells, respectively. In contrast, the lung ad
enocarcinoma and adenosquamous carcinoma cell lines examined did not exhibi
t an increase in c-myc expression relative to the NHBE cells. In summary, t
his reverse/transcriptase polymerase chain reaction method readily quantifi
es and distinguishes the level of c-myc mRNA in NHBE and human lung cancer
cells. This technology may serve to characterize oncogene-related changes d
uring tumorigenesis, to identify genetically predisposed individuals, and t
o allow for earlier diagnosis and treatment of lung cancer.