MOLECULAR-DETECTION OF CANCER-CELLS BY COMPETITIVE REVERSE TRANSCRIPTION-POLYMERASE CHAIN-REACTION ANALYSIS OF SPECIFIC CD44 VARIANT RNAS

Background: CD44 is a cell surface glycoprotein implicated in such div erse biologic processes as lymphocyte activation and homing, extracell ular matrix adhesion, and cellular migration, Primary transcripts of t he CD44 gene can be alternatively spliced to produce a variety of mess enger RNA (mRNA) species, The standard form of CD44 mRNA contains sequ ences from at least 20 genomic exons; variant mRNAs contain sequences from one or more additional exons (v1-10), Predominant expression of a specific CD44 variant, i.e., CD44v8-10, in several human carcinomas h as been described previously, In this study, we developed a novel mole cular approach for detecting cancer cells that overexpress CD44v8-10 m RNA, Methods: After finding that CD44v8-10 was predominantly expressed in non-small-cell lung and bladder carcinomas and that CD44v10 was pr edominantly expressed in leukocytes, we developed a competitive revers e transcription-polymerase chain reaction assay (CC-RT-PCR) that allow s quantification of the relative expression of these two mRNA species in clinical specimens (i.e., determination of a v8-10/v10 ratio), CC-R T-PCR analysis was applied to pleural effusion specimens from patients with benign or malignant lung diseases as well as to spontaneously vo ided urine samples from patients with benign or malignant urologic dis eases, Results: Fifty two of 54 samples from patients with benign dise ases expressed CD44v10 predominantly (v8-10/v10 ratio less than or equ al to 0.65), whereas 46 of 61 samples from patients with malignant dis eases expressed CD44v8-10 predominantly (v8-10/v10 ratio >1.00) (two-s ided P<.001). CC-RT-PCR detected predominant expression of CD44v8-10 i n cytologically negative samples from 11 patients who were later diagn osed with malignant disease, Conclusions: CC-RT-PCR analysis of CD44v8 -10 expression could be an important adjunct to cytologic examination in cancer diagnosis, especially in detecting exfoliated cancer cells i n pleural effusions and urine.