Quantification of caveolin isoforms using quantitative real-time RT-PCR, and analysis of promoter CpG methylation of caveolin-1α in human T cell leukemia cell lines

Abstract

Caveolin-1, an essential structural component of caveolae, functions as a negative regulator for signal transduction and has been suggested to be a candidate tumor suppressor. Lack of caveolin-1 expression has been implicated in the pathogenesis of oncogenic cell transformation and tumorigenesis in many cancers. On the other hand, overexpression has also been associated with tumor progression and metastasis in prostate cancers. Hence, alteration of caveolin-1 expression has been proposed as a clinical marker for diagnosis and prognosis in various cancers. For precise analyses of the caveolin expression in human T cell leukemia cell lines, we measured the mRNA levels of caveolin isoforms, caveolin-1α, -1β, -2, and -3 with real-time RT-PCR using external standards for each isoform. In the panel of human T cell leukemia cell lines tested, four cell lines expressed caveolin-1α, -1β and -2, but not -3, which was consistent with the protein levels. The expression profiles in most cell lines are caveolin-1α > caveolin-1β > caveolin-2. Two cell lines did not express either of the caveolin mRNAs. Methylation analyses for the CpG sites in the promoter region of a positive and a negative cell line did not show a clear correlation with the expression status, suggesting that mechanisms other than CpG methylation are involved in the regulation of caveolin-1α expression in human T cell leukemia cell lines.