Inverse correlation of epidermal growth factor receptor messenger RNA induction and suppression of anchorage-independent growth by OSI-774, an epidermal growth factor receptor tyrosine kinase inhibitor, in glioblastoma multiforme cell lines.
OBJECTIVE
Quantitative and qualitative alterations in the epidermal growth factor receptor (EGFR) commonly occur in many cancers in humans, including malignant gliomas. The aim of the current study was to evaluate molecular and cellular effects of OSI-774, a novel EGFR tyrosine kinase inhibitor, on nine glioblastoma multiforme (GBM) cell lines.


METHODS
The effects of OSI-774 on expression of EGFR messenger (m)RNA and protein, proliferation, anchorage-independent growth, and apoptosis were examined using semiquantitative reverse transcription-polymerase chain reaction, immunocytochemical analysis, Coulter counting, soft agar cloning, and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling/fluorescence-activated cell sorting, respectively. All p53 genes were completely and bidirectionally sequenced. Suppression of anchorage-independent growth by OSI-774 was inversely correlated to the induction of EGFR mRNA during relative serum starvation (r = -0.74) and was unrelated to p53 status. Overall, suppression of anchorage-independent growth was a considerably stronger effect of OSI-774 than inhibition of proliferation. The extent of OSI-774-induced apoptosis positively correlated with both proliferation and anchorage-independent growth of GBM cell lines (r = 0.75 and 0.79, respectively). In a single cell line derived from a secondary GBM, exposure to concentrations of greater than or equal to 1 micromol/L resulted in a substantial net cell loss during proliferation studies.


CONCLUSIONS
The induction of EGFR mRNA may constitute a cellular mechanism to counteract the inhibitory effect of OSI-774 on the anchorage-independent growth of GBM cells. In contrast, no considerable correlation could be established between baseline expression levels of EGFR (both mRNA and protein) in GBM cell lines and their biological response to OSI-774. The OSI-774 induced greater (p53-independent) apoptosis in more malignant GBM phenotypes and may be a promising therapeutic agent against secondary GBM.
Halatsch
Marc-Eric
ME
Klinik und Poliklinik für Neurochirurgie, Georg-August-Universität, Göttingen, Germany. halatsch@aol.com
Gehrke
Esther E
EE
Vougioukas
Vassilios I
VI
Bötefür
Ingolf C
IC
A-Borhani
Farhad
F
Efferth
Thomas
T
Gebhart
Erich
E
Domhof
Sebastian
S
Schmidt
Ursula
U
Buchfelder
Michael
M
D000199:Actins / Q000187:drug effects; D017209:Apoptosis / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor / Q000187:drug effects / Q000473:pathology; D002465:Cell Movement / Q000187:drug effects; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000187:drug effects; D066246:ErbB Receptors / Q000037:antagonists & inhibitors* / Q000187:drug effects* / Q000235:genetics*; D000069347:Erlotinib Hydrochloride; D016158:Genes, p53 / Q000235:genetics; D005909:Glioblastoma / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D016133:Polymerase Chain Reaction / Q000187:drug effects*; D011799:Quinazolines / Q000008:administration & dosage / Q000494:pharmacology*; D012333:RNA, Messenger / Q000187:drug effects* / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D000199:Actins; D017931:DNA Primers; D018076:DNA, Complementary; D011799:Quinazolines; D012333:RNA, Messenger; D000069347:Erlotinib Hydrochloride; D066246:ErbB Receptors