| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Division of Endocrinology and Metabolism, Department of Medicine (D.L., Z.L., D.J., M.X.), and Department of Surgery (A.P.D.), the Johns Hopkins University School of Medicine, Baltimore, Maryland 21287
Address all correspondence and requests for reprints to: Michael Mingzhao Xing, M.D., Ph.D., Division of Endocrinology and Metabolism/Department of Medicine, Johns Hopkins University School of Medicine, 1830 East Monument Street, Suite 333, Baltimore, Maryland 21287. E-mail: mxing1{at}jhmi.edu.
 |
Abstract |
|---|
 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Objective: The objective of the study was to investigate genotype-dependent therapeutic potential of the MEK inhibitor CI-1040 for thyroid cancer.
Experimental Design: We examined the effects of CI-1040 on proliferation, apoptosis, transformation, thyroid gene reexpression, and xenograft tumor growth with respect to genotypes in 10 thyroid tumor cell lines.
Results: Cell proliferation was potently inhibited by CI-1040 in cells harboring BRAF or RAS mutations but not in cells harboring RET/PTC rearrangement or wild-type alleles. For example, the IC50 values for BRAF mutation-harboring KAT10 cells and DRO cells and H-RAS mutation-harboring C643 cells were 0.365, 0.031, and 0.429 µM, respectively, whereas the IC50 values for RET/PTC1-harboring TPC1 cells and the wild-type MRO and WRO cells were 44, 46, and 278 µM, respectively. Proapoptotic effect of CI-1040 was seen in DRO cells, and cytostatic effect was seen in other cells. Down-regulation of cyclin D1 and reexpression of some thyroid genes were induced by CI-1040 in some BRAF mutation-harboring cells, and transformation was inhibited in all cells. CI-1040 also inhibited the growth of xenograft tumors in nude mice derived from KAT10 or C643 cells but not that derived from MRO cells.
Conclusions: We for the first time demonstrated potent inhibitory effects of a MEK inhibitor, CI-1040, on thyroid cancer cells, some of which, particularly cell proliferation and tumor growth, seemed to be BRAF mutation or RAS mutation selective. Our data encourage a clinical trial on CI-1040 in thyroid cancer patients.
|
Introduction |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
The RAS 
RAF MAPK kinase (MEK) MAPK/ERK signaling pathway (MAPK pathway) regulates cell proliferation, differentiation, and survival (7, 8). Aberrant activation of this pathway plays a critical role in the tumorigenesis of human cancers (9, 10, 11, 12). The MAPK pathway is particularly important in thyroid cancer because it harbors several activating mutations in this pathway with a high prevalence, including BRAF mutation, RAS mutation, and RET/PTC rearrangement (13, 14, 15, 16). The T1799A BRAF mutation, which causes a V600E amino acid change and constitutively activates the BRAF kinase, is particularly frequent in PTC and ATC, present in 44% of the former and 25% of the latter (14), and plays an important role in their tumorigenesis (13, 14, 15, 17). Thus, as for other cancers (10, 11, 12), targeted inhibition of the MAPK pathway may potentially be an effective therapy for thyroid cancer.
A potent MEK inhibitor, CI-1040 (18), entered phase I and II clinical trials on several human cancers, which have recently been completed (19, 20). Excellent patient tolerance, safety profiles, and bioavailability were demonstrated, but disappointingly, no consistent significant antitumor activity was shown, although disease stabilization was seen. It was recently demonstrated that BRAF mutation was a prerequisite for the sensitivity to MEK inhibitors in many cancer cell lines (21). Thus, the modest response to CI-1040 in these clinical trials might be explained by the fact that the cancers included in the trials, including mainly non-small cell lung, breast, colon, and pancreatic cancers, rarely or infrequently harbor BRAF mutation. Given the high prevalence of BRAF mutation in PTC and ATC, we speculate that CI-1040 could be an effective therapeutic agent for these cancers. To test this idea, we conducted the present preclinical study on the effects of this compound on thyroid cancer cells with various genotypes in the MAPK pathway.
|
Materials and Methods |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Human benign thyroid hyperplasia cell line KAK1 and PTC cell lines KAT5, KAT7, and KAT10 were a kind gift from Dr. Kenneth B. Ain (University of Kentucky Medical Center, Lexington, KY); the PTC cell line NPA, ATC cell line DRO, and FTC cell lines MRO and WRO were from Dr. Guy J. F. Juillard (University of California, Los Angeles, School of Medicine, Los Angeles, CA); the ATC cell line C643 was from Dr. N. E. Heldin (University of Uppsala, Uppsala, Sweden); and the TPC1 cell line was provided by Dr. Alan P. Dackiw. These cell lines were routinely cultured at 37 C in RPMI 1640 medium supplemented with 10% calf serum, 1 mM sodium pyruvate, 0.1 mM nonessential amino acids, and penicillin-streptomycin in a 37 C humidified incubator with 5% CO2. For some experiments, cells were treated with CI-1040 with the indicated concentrations and time, and the medium and agents were replenished daily. The CI-1040 compound was obtained from Pfizer Global Research and Development (Ann Arbor, MI), dissolved in dimethylsulfoxide (DMSO) with a stock concentration of 10 mM, and stored at –20 C.
Western blotting analysis
Cells were lysed in the radioimmunoprecipitation assay buffer supplemented with phosphatase and protease inhibitors (Sigma, St. Louis, MO). Cellular proteins were resolved on denaturing polyacrylamide gels, transferred to polyvinyl difluoride membranes (Amersham Pharmacia Biotech, Piscataway, NJ), and blotted with appropriate primary antibodies including antiactin (Sc-1616-R), anti-phospho-ERK (Sc-7383), anti-ERK2 (Sc-154), and anti-cyclin D1 (sc718) from Santa Cruz Biotechnology (Santa Cruz, CA), and anti-poly-ADP-ribose polymerase (PARP) (no. 9542) from Cell Signaling (Boston, MA). This was followed by incubation with horseradish peroxidase-conjugated antirabbit (Sc-2004) or antimouse (Sc-2005) IgG antibodies from Santa Cruz, and antigen-antibody complexes were visualized using the chemiluminescent ECL detection system (Amersham Pharmacia Biotech).
Cell proliferation assay
Cells (800/well) were seeded into a 96-well plate and cultured with CI-1040 at the indicated concentrations of CI-1040. 3-(4,5-Dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) assay was used to evaluate cell proliferation. After 5 d of CI-1040 treatment, cell culture was added with 10 µl of 5 mg/ml MTT (Sigma) and incubated for 4 h, followed by addition of 100 µl of 10% sodium dodecyl sulfate solution and incubation for another 12 h. The plates were then read on a microplate reader using a test wavelength of 570 nm and a reference wavelength of 670 nm. Four duplicates were done to determine each data point. IC50 values were calculated using the Reed-Muench method (22).
DNA fragmentation analysis
After treatment with or without 0.5 µM CI-1040 for 3 d, approximately 106 cells were lysed in 200 µl of a buffer containing 10 mM Tris-HCl (pH 8.0), 150 mM NaCl, 10 mM EDTA, 0.4% sodium dodecyl sulfate, and 100 µg/ml proteinase K and incubated at 48 C for 5 h. DNA was purified by standard phenol-chloroform extraction and ethanol precipitation. Dry DNA pellets were resuspended in buffer of 10 mM Tris-HCl (pH 7.5), and 1 mM EDTA containing 0.2 mg/ml ribonuclease A. Samples were loaded on a 1.8% agarose gel and visualized by ethidium bromide staining.
Anchorage-independent growth assays
For anchorage-independent growth assay on soft agar, 4000 cells/well for KAT5, KAT7, KAT10, DRO, and NPA cells or 8000 cells/well for MRO and WRO cells were seeded in six-well plates in 0.3% agar over a bottom layer of 0.6% agar. After 12 d of culture, cell colony number was counted under a microscope and photograph was taken.
RNA extraction and RT-PCR analysis
Total RNA of cell lines was isolated using the TRIzol Reagent (Invitrogen, Carlsbad, CA). Normal human thyroid RNA samples from (Stratagene, La Jolla, CA) were used as controls. The reverse transcription synthesis of DNA was conducted using the SuperScript first-strand synthesis kit (Invitrogen). RT-PCR of the gene for β-actin was used for quality control. PCR was performed with Platinum Taq DNA polymerase (Invitrogen), 1.5 mM MgCl2, 0.2 mM deoxynucleotide triphosphate, and 0.335 µM each primer. The RT-PCR primers for the gene for thyroid-stimulating hormone receptor (TSHR) were 5'-ATCAGGAGGAGGACTTCAGA-3' (forward) and 5'-TTTGAGGGCATCAGGGTCTA-3' (reverse). Primers for the gene for thyroglobulin (Tg) were 5'-GCAAAGGCTGTGAAGCAATT-3' (forward) and 5'-TGATAAAGTAGTCCCGGGTG-3' (reverse). Primers for β-actin were 5'-TCTACAATGAGCTGCGTGTG-3' (forward) and 5'-TAGATGGGCACAGTGTGGGT-3' (reverse). Representative of two to four experiments is presented in each figure.
Xenograft tumor assay in nude mice
Animal studies were approved using a protocol approved by our institutional Animal Care and Use Committee. Five x 106 cells for KAT10 or C643 and 107 cells for MRO or TPC1 suspended in 200 µl of RPMI 1640 medium were injected sc into flanks of nude mice at the age of 5 wk (Harlan Sprague Dawley, Indianapolis, IN). When tumors grew to about 5 mm after 1 wk, animals were randomly grouped into three groups for each cell line, each consisting of three animals. The three groups were treated daily with the vehicle, 50 mg/kg CI-1040, and 150 mg/kg CI-1040, respectively, through an oral gavage. CI-1040 was formulated in the vehicle containing 0.5% hydroxypropyl methylcellulose and 0.2% Tween 80. Tumor size was measured on the skin surface twice a week and the volume was calculated by the formula (width)2 x length/2 as described previously (23). After 2 wk of treatment, mice were killed and xenograft tumors were removed surgically and weighted. Statistical analysis of differences in tumor volumes and weights between groups was performed using the two-tailed independent-sample t test as described (24). Ten milligrams tissue from the xenograft tumor were obtained for Western blotting analysis of ERK phosphorylation.
|
Results |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
We first analyzed genetic alterations in the MAPK pathway in the human thyroid cancer cell lines used in this study to determine their genotypes. As shown in Table 1
, among the 10 thyroid cancer cell lines used, MRO and WRO cells harbored no mutation, TPC1 cells harbored RET/PTC1 rearrangement, and C643 cells harbored a G37C homozygous H-RAS mutation in codon 13 with a G13R amino acid substitute, which had previously been demonstrated to be an activating mutation (25). The remaining six cell lines all harbored the activating T1799A BRAF mutation, homozygous in NPA and DRO cells and heterozygous in the rest. We next investigated the effect of CI-1040 on the activities of MAPK pathway in these cells. A time course revealed a rapid and effective inhibition of ERK phosphorylation (p-ERK) by CI-1040; at 1 h, p-ERK was completely suppressed by 0.5 µM CI-1040, and this suppression remained through 24 h (Fig. 1). Similar effects of CI-1040 on p-ERK were seen at 24 h in all the thyroid cancer cell lines that harbored activating genetic alterations, including RAS mutation, BRAF mutation, and RET/PTC rearrangement (Fig. 1B). Remarkable inhibition of p-ERK was also seen in MRO and WRO cells that harbored wide-type alleles (see Figs. 1B, 4C, and 6B). Thus, p-ERK was uniformly inhibited by CI-1040 in all the cells regardless of their genotypes in the MAPK pathway. This result is expected if the potent MEK inhibitor can enter all these cells.
|
|
|
|
Given the inhibitory effect of CI-1040 on MAPK pathway signaling in thyroid cancer cells, we next investigated its effect on the proliferation of these cells. As shown in Fig. 2, treatment with CI-1040 potently inhibited proliferation of the cells that harbored BRAF or RAS mutations in a concentration-dependent manner, with IC50 values ranging from 0.031 to 1.251 µM (Table 1
). In these cells, significant inhibition of proliferation occurred at 0.5 µM CI-1040. Proliferation of DRO cells, which harbored a homozygous BRAF mutation and apparently had the highest basal activity of MAPK pathway (Fig. 1 and data not shown), was the most sensitive to CI-1040 treatment with the lowest IC50 (0.031 µM) among the 10 cell lines (Table 1). At only 0.1 µM of CI-1040, about 80% inhibition of proliferation was achieved, and 1 µM CI-1040 nearly completely suppressed the proliferation of DRO cells. In contrast, proliferation of MRO and WRO cells, which harbored no known genetic alterations in the MAPK pathway, was virtually not affected by CI-1040, with IC50 values of 46.227 and 278.286 µM, respectively (Table 1). Surprisingly, CI-1040 virtually had no effect on proliferation of TPC1 cells, which harbored RET/PTC1 rearrangement, with an IC50 in the similar range of those in MRO and WRO cells (Table 1), although this compound significantly inhibited the MAPK pathway in TPC1 cells (Fig. 1B). Thus, the MEK inhibitor CI-1040 selectively inhibited proliferation of thyroid cancer cells harboring BRAF or RAS mutations.
|
Anchorage-independent colony formation in soft agar is a characteristic of cell transformation. We examined the effects of CI-1040 on this property of thyroid cancer cells. As shown in Fig. 3, all the BRAF mutation-harboring cells, including KAT5, KAT7, KAT10, DRO, and NPA cells, and the H-RAS mutation-harboring C643 cells showed a strong ability to form colonies in soft agar. MRO and WRO cells, which did not harbor BRAF or RAS mutations, formed smaller and fewer colonies. These results are consistent with the activating oncogenic functions of the V600E BRAF and the G13R H-RAS (25, 26, 27). Interestingly, treatment with CI-1040 inhibited anchorage-independent growth of all these thyroid cancer cell lines regardless of their genotypes in the MAPK pathway (Fig. 3), in contrast to the genotype-selective effects of CI-1040 on the proliferation of these thyroid cancer cells (Table 1 and Fig. 2). Colony formation of TPC1 cells on soft agar was similarly inhibited by CI-1040 (data not shown). It thus appears that, unlike proliferation, anchorage-independent growth requires intact MAPK pathway signaling in all of the thyroid cancer cells tested.
|
We next investigated the molecular mechanisms underlying the inhibition of cell growth by CI-1040. Shown in Fig. 4 are the results on representative thyroid cancer cell lines KAT7, DRO, C643, and MRO cells, which harbored heterozygous BRAF mutation, homozygous BRAF mutation, homozygous RAS mutation, and wild-type alleles, respectively (Table 1). We found that within 72 h of treatment with 0.5 µM CI-1040, a majority of the DRO cells had shrunk, become round, developed small blebs, and detached from the dish, indicating apoptotic cell death (Fig. 4A), similar to apoptosis of some other human cancer cells induced by inhibition of the MAPK pathway (10, 28). The apoptotic death of DRO cells after CI-1040 treatment was confirmed biochemically by the formation of DNA ladder (Fig. 4B), which represents internucleosomal DNA fragmentation (29), and cleavage of the 113-kDa PARP (Fig. 4C), which is a substrate of certain caspases and is cleaved into fragments of approximately 89 and 24 kDa during early stages of apoptosis (30). In DRO cells, increasing cleavage of PARP occurred in association with increasing concentration of CI-1040 and decreasing p-ERK level (Fig. 4C), indicating that apoptosis was mediated through inhibition of the MAPK pathway. The CI-1040 compound also decreased expression of cyclin D1 in DRO cells (Fig. 4C), a key cell cycle-regulatory molecule up-regulated by the MAPK pathway (31, 32). Therefore, CI-1040 inhibited DRO growth/proliferation through inducing both cell apoptotic death and cell cycle arrest. In KAT7 cells, CI-1040 treatment down-regulated cyclin D1 expression in a concentration-dependent manner (Fig. 4C) but had no significant effect on DNA fragmentation (Fig. 4B) or PARP cleavage (Fig. 4C), suggesting that CI-1040 inhibited KAT7 proliferation through cell cycle arrest. In C643 cells, CI-1040 had no effect on DNA fragmentation (Fig. 4B), PARP cleavage (Fig. 4C), or cyclin D1 expression (Fig. 4C), although it inhibited the MAPK pathway in this cell (Fig. 1). No significant basal cyclin D1 expression and no DNA fragmentation or PARP cleavage after CI-1040 treatment were seen in MRO cells (Fig. 4, B and C). These molecular events were also not seen in KAK1, KAT5, KAT10, and NPA cells (data not shown). Thus, different molecular processes were involved in the inhibition of cell proliferation by CI-1040 through inhibition of MEK in different thyroid cancer cells.
CI-1040 treatment promoted differentiation of thyroid cancer cells
Previous studies in differentiated rat thyroid cells showed that forced expression of mutant BRAF or mutant RAS caused silencing of thyroid-specific genes, such as Tg and TSHR genes, a hallmark of dedifferentiation of thyroid cancer cells (33, 34, 35). We previously found that the MEK inhibitor U0126 could induce partial restoration of TSHR expression in NPA cells (36). We similarly explored such effects of CI-1040 and found that expression of the Tg gene, which was expressed naturally but at a very low level in DRO cells, could be significantly enhanced by CI-1040 treatment, although expression of the TSHR gene could not be restored (Fig. 5). In NPA cells, expression of both TSHR and Tg genes was restored or enhanced by treatment of cells with CI-1040 (Fig. 5). These results were not consistently seen in other thyroid cancer cell lines (data not shown). The data suggest that CI-1040 can promote differentiation of some thyroid cancer cells.
|
To evaluate further the therapeutic potential of the MEK inhibitor CI-1040, we examined the effects of CI-1040 on the growth of xenograft tumors in nude mice derived from thyroid cancer cell lines. Four cell lines, including KAT10, C643, TPC1, and MRO cells, which harbored the BRAF mutation, RAS mutation, RET/PTC rearrangement, and wild-type alleles, respectively, were injected sc into flanks of nude mice to produce tumors for the testing of orally administered CI-1040. TPC1 cells were apparently incompatible with these mice and failed to grow significant tumors and were therefore left out from further experiments. As shown in Fig. 6A, the growth of tumors derived from KAT10 cells was significantly inhibited by CI-1040 at the higher one of the two doses tested; at 2 wk of treatment, the average tumor volumes and weights were 1.116 ± 0.223 cm3 and 0.850 ± 0.030 g, respectively, in the control group vs. 0.611 ± 0.254 cm3 and 0.487 ± 0.124 g, respectively, in the group treated daily with 150 mg/kg CI-1040 (P = 0.06 and 0.008, respectively). The KAT10 tumor volumes and weights were 0.940 ± 0.460 and 0.747 ± 0.204 in the group treated with CI-1040 at 50 mg/kg and were not significantly different from the control group (P = 0.58 and 0.43, respectively) (Fig. 6A). For C643-derived tumors, the volumes and weights at 2 wk of treatment were 0.742 ± 0.052 cm3 and 0.733 ± 0.154 g, respectively, in the control group vs. 0.545 ± 0.141 cm3 and 0.540 ± 0.087 g, respectively, in the group treated with 50 mg/kg CI-1040 (P = 0.09 and 0.13, respectively) and vs. 0.545 ± 0.057 cm3 and 0.393 ± 0.072 g, respectively, in the group treated with 150 mg/kg CI-1040 (P = 0.01 and 0.03, respectively). Thus, growth of C643-derived tumors was significantly inhibited by CI-1040 at the daily dose of 150 mg/kg. No significant inhibitory effects of the CI-1040 compound were found on the growth of MRO cell-derived tumors (Fig. 6A); the tumor volumes and weights were 0.657 ± 0.375 and 0.677 ± 0.443, respectively, in the control group vs. 0.563 ± 0.243 and 0.647 ± 0.370, respectively, in the group treated with 50 mg/kg CI-1040 (P = 0.73 and 0.93, respectively) and vs. 0.671 ± 0.308 and 0.737 ± 0.439, respectively, in the group treated with 150 mg/kg CI-1040 (P = 0.96 and 0.88, respectively).
To verify the in vivo effects of CI-1040 on the MAPK pathway, we examined the p-ERK level in tumors harvested 3–4 h from the last administration of CI-1040 at the indicated doses and found a dose-dependent inhibition of p-ERK, with a marked inhibition with 150 mg/kg, in all the three cell-derived xenograft tumors (Fig. 6B). As seen for the relationship between suppression of the MAPK pathway and inhibition of cell proliferation in the in vitro studies (Figs. 1 and 2 and Table 1), in these in vivo studies, a correlation between suppression of the MAPK pathway and inhibition of the tumor growth was seen for KAT10 and C643 cells but not for MRO cells (Fig. 6).
|
Discussion |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
The CI-1040 compound is a potent dual inhibitor of both MEK1 and MEK2 that exhibits significant antitumor activities in in vitro and in vivo studies (18, 21, 40). We investigated the therapeutic potential of CI-1040 for thyroid cancer by examining its effects on a large number of human thyroid tumor cell lines with different genotypes in the MAPK pathway. We demonstrated that CI-1040 selectively inhibited proliferation of thyroid cancer cells and their xenograft tumors with BRAF and RAS mutations but not cells without these genetic alterations. Cell differentiation was also promoted by CI-1040 in some BRAF mutation-harboring thyroid cancer cells as reflected by the reexpression of some thyroid-specific genes. Therefore, BRAF and RAS mutations, through activating the MAPK pathway, both confer thyroid cancer cells sensitivity to the MEK inhibitor. Interestingly, CI-1040 virtually had no effect on the proliferation of PTC-derived TPC1 cells that harbored RET/PTC1 rearrangement, although it effectively inhibited the MAPK pathway in these cells. It is likely that MEK inhibitor-insensitive signaling pathways linked to the RET/PTC, other than the conventional ERK/MAPK pathway signaling, may play an important role in the proliferation of RET/PTC-harboring thyroid cancer cells. These may include, for example, the phosphatidylinositol 3-kinase, Rac, p38 MAPK, and c-Jun N-terminal kinase signaling pathways, which can all be coupled to RET signaling (41, 42). In contrast, CI-1040 inhibited anchorage-independent growth of all the thyroid cancer cells tested, regardless of their genotypes (Fig. 3), suggesting that the MAPK pathway signaling may be required to maintain the transformed state of thyroid cancer cells apparently regardless of their oncogenic backgrounds. This is consistent with the recent demonstration in breast cancer cells that the MAPK pathway, like the phosphatidylinositol 3-kinase/Akt pathway, was required for cell transformation (43).
Although MRO and WRO cells used in the present study were originally derived from FTC, a major genetic difference between them and the cells that responded to the MEK inhibitor was whether they harbored BRAF or RAS mutations. Even KAK1 cells, which were originally derived from benign thyroid hyperplasia and developed BRAF mutation apparently during long-term maintenance culture, responded potently to CI-1040 (Fig. 2). BRAF and RAS mutations are strong oncogenic activators of the MAPK pathway and thyroid cancer cells harboring them have likely developed dependence on the aberrantly activated signaling of this pathway for survival, as seen in other types of cancer cells harboring these mutations (21). Proliferation and tumor growth of MRO and WRO cells, which do not harbor major genetic alterations in the MAPK pathway, may depend on other genetic alterations and related signaling abnormalities but not the MAPK pathway. Therefore, it appears that the differential effects of CI-1040 on thyroid cancer cell proliferation and tumor growth in the present study were mainly a result of the difference in genotypes in the MAPK pathway in the cells. However, we cannot be definitively conclusive on the selectivity of BRAF mutation or RAS mutation for the inhibitory effects of CI-1040 on the proliferation and tumor growth of thyroid cancer cells as the cells studied were likely also not identical in genetic patterns other than their different genotypes in the MAPK pathway. Interestingly, as summarized in Table 2, unlike BRAF mutation, the RAS mutation-dependent sensitivity of CI-1040 seemed to be cancer type selective (21, 44). This information may be useful in guiding clinical use of MEK inhibitors in different human cancers.
|
In summary, we for the first time investigated the effects of a MEK inhibitor, CI-1040, on thyroid cancer cells both in vitro and in vivo and demonstrated its selective inhibition of proliferation and tumor growth of cells harboring BRAF or RAS mutations but not cells harboring RET/PTC1 rearrangement or wild-type alleles. Because CI-1040 had an excellent clinical patient tolerance and safety profile and thyroid cancers, particularly PTC and ATC, frequently harbor BRAF and RAS mutations, this compound may prove to be a safe and effective therapeutic agent for thyroid cancer. Our results encourage a clinical trial on CI-1040, particularly in patients with conventionally incurable thyroid cancer that harbors BRAF or RAS mutations.
|
Acknowledgments |
|---|
|
Footnotes |
|---|
Disclosure Statement: The authors have nothing to disclose.
First Published Online October 2, 2007
Abbreviations: ATC, Anaplastic thyroid cancer; DMSO, dimethylsulfoxide; FTC, follicular thyroid cancer; MEK, MAPK kinase; MTT, 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide; PARP, poly-ADP-ribose polymerase; p-ERK, ERK phosphorylation; PTC, papillary thyroid cancer; Tg, thyroglobulin; TSHR, thyroid-stimulating hormone receptor.
Received January 16, 2007.
Accepted September 20, 2007.
|
References |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
This article has been cited by other articles:
 |
|
 |
|
  J P. Couto, H Prazeres, P Castro, J Lima, V Maximo, P Soares, and M Sobrinho-Simoes How molecular pathology is changing and will change the therapeutics of patients with follicular cell-derived thyroid cancer J. Clin. Pathol., May 1, 2009; 62(5): 414 - 421. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y. C. Henderson, S.-H. Ahn, and G. L. Clayman Inhibition of the Growth of Papillary Thyroid Carcinoma Cells by CI-1040 Arch Otolaryngol Head Neck Surg, April 1, 2009; 135(4): 347 - 354. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. E. Schweppe, J. P. Klopper, C. Korch, U. Pugazhenthi, M. Benezra, J. A. Knauf, J. A. Fagin, L. A. Marlow, J. A. Copland, R. C. Smallridge, et al. Deoxyribonucleic Acid Profiling Analysis of 40 Human Thyroid Cancer Cell Lines Reveals Cross-Contamination Resulting in Cell Line Redundancy and Misidentification J. Clin. Endocrinol. Metab., November 1, 2008; 93(11): 4331 - 4341. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. S. Anglesio, J. M. Arnold, J. George, A. V. Tinker, R. Tothill, N. Waddell, L. Simms, B. Locandro, S. Fereday, N. Traficante, et al. Mutation of ERBB2 Provides a Novel Alternative Mechanism for the Ubiquitous Activation of RAS-MAPK in Ovarian Serous Low Malignant Potential Tumors Mol. Cancer Res., November 1, 2008; 6(11): 1678 - 1690. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. G. Pfister and J. A. Fagin Refractory Thyroid Cancer: A Paradigm Shift in Treatment Is Not Far Off J. Clin. Oncol., October 10, 2008; 26(29): 4701 - 4704. [Full Text] [PDF]
|
|
|
|
|
|
R. Leboeuf, J. E. Baumgartner, M. Benezra, R. Malaguarnera, D. Solit, C. A. Pratilas, N. Rosen, J. A. Knauf, and J. A. Fagin BRAFV600E Mutation Is Associated with Preferential Sensitivity to Mitogen-Activated Protein Kinase Kinase Inhibition in Thyroid Cancer Cell Lines J. Clin. Endocrinol. Metab., June 1, 2008; 93(6): 2194 - 2201. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Endocrinology | Endocrine Reviews | J. Clin. End. & Metab. |
| Molecular Endocrinology | Recent Prog. Horm. Res. | All Endocrine Journals |
