Distinct genetic alterations in the mitogen-activated protein kinase pathway dictate sensitivity of thyroid cancer cells to mitogen-activated protein kinase kinase 1/2 inhibition.
BACKGROUND
The mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) pathway plays an important role in papillary and anaplastic thyroid cancer (PTC and ATC) due to activating mutations in BRAF, RAS, or rearrangements in RET/PTC1. The objective of this study was to thoroughly test whether the BRAF V600E mutation predicts response to mitogen-activated protein kinase kinase 1/2 (MKK1/2) inhibition, as shown in other tumor types, using an authenticated panel of thyroid cancer cell lines.


METHODS
PTC and ATC cells harboring distinct mutations in the MAPK pathway were treated with two different inhibitors selective for MKK1/2 (CI-1040 or U0126). The consequences of MKK1/2 inhibition on cell growth, survival, invasion, and MAPK signaling was determined.


RESULTS
Inhibition of MKK1/2 using CI-1040 or U0126 differentially inhibits the growth of a panel of PTC and ATC cell lines in two-dimensional culture, with those harboring the BRAF V600E mutation (SW1736) or BRAF-V600E/PI3K-E542K mutations (K1) being the most sensitive, the RET/PTC1 rearrangement (TPC1) and BRAF V600E mutant (BCPAP), intermediate, and the HRAS-G13R mutant (C643), the least sensitive. Growth of these cells is more sensitive to MKK1/2 inhibition when grown in 2% versus 10% serum. Baseline levels of phospho-ERK1/2 were similar in all of the cell lines, and inhibition phospho-ERK1/2 did not predict sensitivity to MKK1/2 inhibition. When cells are grown in three-dimensional culture, MKK1/2 inhibition of growth correlates with mutational status (BRAF > RET/PTC1 > RAS). Finally, PTC and ATC invasiveness is differentially inhibited by CI-1040, which is independent of tumor type or mutation present.


CONCLUSIONS
Different mutations in the MAPK pathway play distinct roles in the growth and invasion of thyroid cancer cells. These results indicate that MKK1/2 inhibitors have the potential to inhibit thyroid cancer growth and invasion, but that responses differ based on mutation status and growth conditions.
Schweppe
Rebecca E
RE
University of Colorado Denver, Aurora, 80045, USA. rebecca.schweppe@ucdenver.edu
Kerege
Anna A
AA
Sharma
Vibha
V
Poczobutt
Joanna M
JM
Gutierrez-Hartmann
Arthur
A
Grzywa
Rachel L
RL
Haugen
Bryan R
BR
D001549:Benzamides / Q000494:pharmacology; D002070:Butadienes / Q000494:pharmacology; D002277:Carcinoma / Q000188:drug therapy* / Q000201:enzymology* / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D004354:Drug Screening Assays, Antitumor; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D048369:MAP Kinase Kinase 1 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D048370:MAP Kinase Kinase 2 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D020935:MAP Kinase Signaling System; D009154:Mutation; D009570:Nitriles / Q000494:pharmacology; D015398:Signal Transduction; D013964:Thyroid Neoplasms / Q000188:drug therapy* / Q000201:enzymology* / Q000473:pathology
C120227:2-(2-chloro-4-iodophenylamino)-N-cyclopropylmethoxy-3,4-difluorobenzamide; D001549:Benzamides; D002070:Butadienes; D004791:Enzyme Inhibitors; D009570:Nitriles; C113580:U 0126; C482128:MAP2K2 protein, human; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; C482125:MAP2K1 protein, human