Biomedical subjects

Talya Kunik

Publications and source records attributed to Talya Kunik.

3 recordsLinked to original sources

PubMed2006

Mammalian cells.

Agrobacterium most likely can transform virtually all known plant species, and experimental protocols for Agrobacterium-mediated genetic transformation of yet more plant species, ecotypes, and cultivars are published almost on a daily basis. Interestingly, the Agrobacterium host range is not limited to the plant kingdom, and it has been shown to transform many species of fungi and even prokaryotes. The ability of Agrobacterium to genetically transform HeLa cells further widens the range of potential hosts of Agrobacterium to include humans and perhaps other animal species. Furthermore, because mammalian cells significantly differ from plant cells, they provide a useful experimental system for identification and functional characterization of plant-specific factors involved in the transformation process. Here, we present basic procedures for transfection and Agrobacterium-mediated genetic transformation of mammalian cells. We also demonstrate the use of mammalian cells for studies of the cellular components of the genetic transformation pathway.

Agrobacterium tumefaciens↗

PubMed2004

Celecoxib but not rofecoxib inhibits the growth of transformed cells in vitro.

PURPOSE: Nonsteroidal anti-inflammatory drugs reduce the risk of colorectal cancer. The cyclooxygenase (COX) pathway of arachidonic acid metabolism is an important target for nonsteroidal anti-inflammatory drugs. Increased expression of COX-2 was recently shown to be an important step in the multistep process of colorectal cancer carcinogenesis. The new COX-2-specific inhibitors offer the benefit of cancer protection without the gastrointestinal toxicity reported for the old drugs. The purpose of this study was to compare the growth effects of two specific COX-2 inhibitors, celecoxib (Pfizer, Inc., New York, NY), and rofecoxib (Merck, White House Station, NJ) in normal and transformed enterocytes. EXPERIMENTAL DESIGN: Cultures of normal rat intestinal epithelial cell line, IEC-18, vector control cells, c-K-ras, c-K-ras-bak, and antisense-bak derivatives were treated with different dosages of celecoxib (0-60 micro M) and rofecoxib (0-20 micro M). Cell cycle analysis and apoptosis were assessed by fluorescence-activated cell sorting analysis. Protein expression was assessed by Western blot analysis and caspases 3 and 8 activities by ELISA. RESULTS: Celecoxib inhibited cell growth and induced apoptosis in a time- and dose-dependent manner. IEC18 parental cells were two to four times more resistant to celecoxib than ras, ras-bak, and antisense bak transformed cells that overexpress the COX-2 protein. The induction of apoptosis by celecoxib involved the caspase pathways. Rofecoxib, up to its maximal concentration of 20 micro M, did not inhibit cell growth or induce apoptosis. CONCLUSIONS: Celecoxib may prove to be a very efficient component in the prevention and treatment of gastrointestinal tumors because it inhibits the growth of cancerous cells without affecting the growth of normal cells.

Animals↗

PubMed2003

Oncogenic transformation of normal enterocytes by overexpression of cyclin D1.

Cyclin D1 plays an important role in the multi-step process of gastrointestinal tumorigenesis. We hypothesize that normal enterocytes over-expressing cyclin D1 will demonstrate a transformed phenotype. The nontumorigenic intestinal epithelial cell line, IEC-18, was transfected with the vector pMV7-CCND1, encoding cyclin D1. Three clones, with cyclin D1 levels similar to those seen in colon cancer cell lines, were further evaluated in comparison to the vector control cells. They proliferated faster and demonstrated anchorage-independent growth in soft agar, higher saturation density, and higher plating efficiency. When injected into nude mice, tumors were generated after 6-8 weeks. On the other hand these cells were more sensitive to induction of apoptosis. There was no change in the level of beta-catenin protein. In conclusion, cyclin D1 can act as an oncogene in vitro and in vivo, when produced in immortalized normal intestinal epithelial cells. This model may be useful for understanding the role and interrelationships of cyclin D1 in colorectal tumorigenesis.

Animals↗