Aberrant STYK1 expression in ovarian cancer tissues and cell lines

<p>Abstract</p> <p>Background</p> <p>Overexpression of <it>STYK1</it>, a putative serine/threonine and tyrosine receptor protein kinase has been shown to confer tumorigenicity and metastatic potential to normal cells injected into nude mice. Mutation of a tyrosine residue in the catalytic STYK1 domain attenuates the tumorigenic potential of tumor cells <it>in vivo</it>, collectively, suggesting an oncogenic role for STYK1.</p> <p>Methods</p> <p>To investigate the role of STYK1 expression in ovarian cancer, a panel of normal, benign, and ovarian cancer tissues was evaluated for STYK1 immunoreactivity using STYK1 antibodies. In addition, mRNA levels were measured by reverse transcription PCR and real-time PCR of estrogen receptors, GPR30 and STYK1 following treatment of ovarian cell lines with estrogen or G1, a GPR30 agonist, as well as western analysis.</p> <p>Results</p> <p>Our data showed higher expression of STYK1 in cancer tissues versus normal or benign. Only normal or benign, and one cancer tissue were STYK1-negative. Moreover, benign and ovarian cancer cell lines expressed <it>STYK1 </it>as determined by RT-PCR. Estradiol treatment of these cells resulted in up- and down-regulation of <it>STYK1 </it>despite estrogen receptor status; whereas G-1, a GPR30-specific agonist, increased STYK1 mRNA levels higher than that of estradiol.</p> <p>Conclusion</p> <p>We conclude that <it>STYK1 </it>is expressed in ovarian cancer and is regulated by estrogen through a GPR30 hormone-signaling pathway, to the exclusion of estrogen receptor-alpha.</p

Epigenetics of a tandem DNA repeat: chromatin DNaseI sensitivity and opposite methylation changes in cancers

DNA methylation and chromatin DNaseI sensitivity were analyzed in and adjacent to D4Z4 repeat arrays, which consist of 1 to ∼100 tandem 3.3-kb units at subtelomeric 4q and 10q. D4Z4 displayed hypomethylation in some cancers and hypermethylation in others relative to normal tissues. Surprisingly, in cancers with extensive D4Z4 methylation there was a barrier to hypermethylation spreading to the beginning of this disease-associated array (facioscapulohumeral muscular dystrophy, FSHD) despite sequence conservation in repeat units throughout the array. We infer a different chromatin structure at the proximal end of the array than at interior repeats, consistent with results from chromatin DNaseI sensitivity assays indicating a boundary element near the beginning of the array. The relative chromatin DNaseI sensitivity in FSHD and control myoblasts and lymphoblasts was as follows: a non-genic D4Z4-adjacent sequence (p13E-11, array-proximal)> untranscribed gene standards > D4Z4 arrays> constitutive heterochromatin (satellite 2; P < 10−4 for all comparisons). Cancers displaying D4Z4 hypermethylation also exhibited a hypermethylation-resistant subregion within the 3.3-kb D4Z4 repeat units. This subregion contains runs of G that form G-quadruplexes in vitro. Unusual DNA structures might contribute to topological constraints that link short 4q D4Z4 arrays to FSHD and make long ones phenotypically neutral