2001-2003 Young Investigator Award – Interim Report 3

2001-2003 Young Investigator Award – Interim Report

Multidrug resistance in anaplastic thyroid carcinoma

Investigator: Paul M. Spring, MD, MS

The first year of the two-year award was dedicated to performing multidrug resistance gene expression “profiles” on anaplastic thyroid carcinoma (ATC) cell lines. We surveyed nine separate ATC cell lines for the 8 most thoroughly studied and cited MDR genes. Subsequently, we added pooled normal thyroid tissue and a papillary thyroid carcinoma cell line to demonstrate whether the commonly held belief that ATC derives from a palpable or occult focus of papillary thyroid cancer was manifest by differential expression of MDR genes. The initial MDR gene expression was assayed using standard reverse transcription PCR and later, gene expression was quantitatively analyzed using MDR specific primer-probe sets with Real Time PCR. In summary, we showed that many MDR genes are constitutively expressed and that mdr1, mrp1 and mrp2 are variably expressed.

In the second year, once the gene expression for each cell line had been determined, we selected three ATC cell lines with differential expression of MDR proteins, P-glycoprotein (Pgy; encoded by the mdr1 gene) and MRP1. We then performed cell survival experiments using Taxol and Doxorubicin, substrates for Pgy and MRP1, respectively; inhibition of the MDR drug transporters was achieved using Verapamil and MK571, respectively. The magnitude of MDR inhibition, as reflected in the enhanced cell killing of the ATC cells by lower concentrations of chemotherapy agents, was analyzed statistically and demonstrated a qualitative response to the MDR inhibitor vis-à-vis specific MDR gene expression.

Further studies currently being carried out in the lab are focused on; MDR protein expression; combined chemoradiation treatment of ATC cell lines using MDR inhibitors; and preclinical studies using orthotopic injection of ATC cells in nude mice.

The Young Investigator Award was a key component for generating the momentum that we needed to begin our studies. We are very grateful to the American Head and Neck Society and the Academy for their generous support of this research.

Paul M. Spring, MD, MS, FACS

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