Nancy Wang, Ph.D.

Microcell-mediated transfer of chromosome 11 into ovarian carcinoma cell line, SKOV-3 results in suppression of tumorigenicity in scid/scid mice providing evidence from functional aspect that chromosome 11 carries ovarian tumor suppressor gene(s).

To identify the differentially expressed transcripts associated with suppression of tumorigenicity, cDNA from the tumorigenic clones were subtracted from the non-tumorigenic clones which were then either cloned, sequenced and searched in GenBank, or analyzed by Gene Discovery Array Screening (GDAS). A cDNA transcript corresponding to the gene Thy-1 located (11q23-24) was found to be exclusively expressed in the non-tumorigenic clones. Transfection of Thy-1-antisence to the non-tumorigenic clone, 11(H)9-8, abolished the Thy-1 expression and restored tumorigenicity in scid/scid mice. We therefore, hypothesize that Thy-1 is a putative ovarian tumor suppressor gene (TSG).

To test this hypothesis, the following studies are ongoing: 1) To verify the tumor suppressing nature of Thy-1 and its specificity in fresh/frozen ovarian tumors by Northern blot, immunocytochemistry, and flow cytometry followed by statistical correlation study; 2) To define the effect of Thy-1 on in vivo growth and tumorigenicity by comparative xenographic study in scid/scid between 11(C)9-8-Thy-1-antisense and 11(C)9-8-null, as well as SKOV-3-Thy-1 and SKOV-3-null; 3) To identify the downstream genes associated with Thy-1 by comparative macroarray and microarray analysis combined with suppression subtractive hybridization on the DNA population between SKOV-3-Thy-1 and SKOV-3-null, as well as 11(C)9-8-Thy-1-antisense and 11(C)9-8-null; 4) To identify the sequential signaling pathway of Thy-1 using the in vitro doxycycline (dox) Thy-1 inducible system established in our laboratory. cDNA obtained from SKOV-3-Thy-1-inducible cells at various time post dox exposure will be analyzed and compared between adjacent time points by both macroarray and dual color microarray.

The accomplishment of this study cannot only verify the OVC tumor suppressing nature of Thy-1, but also let us understand the function of this important cell surface marker.