Identification of cell surface and secreted proteins essential for tumor cell survival using a genetic suppressor element screen.

Survival factors play critical roles in regulating cell growth in normal and cancer cells. We designed a genetic screen to identify survival factors which protect tumor cells from apoptosis. A retroviral expression library of random cDNA fragments was constructed from cancer cells and used to transduce the colon carcinoma cell line HCT116.

Identification of potential anticancer drug targets through the selection of growth-inhibitory genetic suppressor elements.

To identify human genes required for tumor cell growth, transcriptome-scale selection was used to isolate genetic suppressor elements (GSEs) inhibiting breast carcinoma cell growth. Growth-inhibitory GSEs (cDNA fragments that counteract their cognate gene) were selected from 57 genes, including known positive regulators of cell growth or carcinogenesis as well as genes that have not been previously implicated in cell proliferation. Many GSE-cognate genes encode transcription factors (such as STAT and AP-1) and signal transduction proteins.

Altered expression of ubiquitous kinesin heavy chain results in resistance to etoposide and hypersensitivity to colchicine: mapping of the domain associated with drug response.

The motor protein kinesin is a tetramer consisting of two heavy and two light chains. Expression of an antisense RNA fragment derived from the mouse ubiquitous kinesin heavy chain (uKHC) cDNA is associated with a unique type of multidrug resistance. We analyzed the effects of retroviral transduction of the human uKHC and its derivatives on drug sensitivity of the human fibrosarcoma cell line HT1080.

Genetic suppressor elements: new tools for molecular oncology--thirteenth Cornelius P. Rhoads Memorial Award Lecture.

Genetic suppressor elements (GSEs) are short biologically active gene fragments that encode dominantly acting peptides or inhibitory antisense RNAs. GSEs can be isolated from a single gene or from a multigene complex by constructing a library of short random fragments of the target gene(s) in an expression vector, followed by expression selection for the desired phenotype in a suitable cellular system. GSE selection from a single gene allows one to develop efficient and specific inhibitors of the gene function and to identify functional protein domains.

Novel replication inhibitory function of the developmental regulator/transcription repressor protein WT1 encoded by the Wilms' tumor gene.

The tumor suppressor/developmental regulator protein WT1 encoded by the Wilms' tumor gene is a zinc finger-containing transcription factor which binds to the G+C-rich motif 5'-GCGGGGGCG-3' and represses transcription. Alternatively spliced variants of WT1 (termed+KTS) having an insertion in the zinc finger region are defective for binding to and hence for repression of transcription from promoters containing this motif. Due to the known interactions of two other tumor suppressor proteins with the simian virus 40 (SV40) oncoprotein large tumor antigen (TAg) [which in one case (p53) results in inhibition of the replication initiation activity of TAg], and because of the presence of G+C-rich sequences in the SV40 origin region, we tested the effect of WT1 on TAg- and SV40 origin-dependent DNA replication.