pd-184352 and Hyperplasia

Tumor cells that are grown in three-dimensional (3D) cell culture exhibit relative resistance to cytotoxic drugs compared with their response in conventional two-dimensional (2D) culture. We studied the effects of targeted agents and doxorubicin on 2D and 3D cultures of human breast cell lines that represent the progression from normal epithelia (modeled by MCF10A cells) through hyperplastic variants to a dysplastic/carcinoma phenotype (MCF10.DCIS cells), variants transformed by expression of activated Ras, and also a basal-subtype breast carcinoma cell line (MDA-MB-231). The results showed the expected relative resistance to the cytotoxic agent doxorubicin in 3D cultures, with greater resistance in normal and hyperplastic cells than in carcinoma models. However, the response to the targeted inhibitors was more complex. Inhibition of mitogen-activated protein kinase kinase (MEK) by either 1,4-diamino-2,3-dicyano-1,4-bis(methylthio)butadiene (U0126) or 2-(2-chloro-4-iodo-phenylamino)-N-cyclopropylmethoxy-3,4-difluoro-benzamide (CI-1040, PD184352) produced a similar inhibition of the growth of all the MCF10 cell lines in 2D. In 3D culture, the normal and hyperplastic models exhibited some resistance, whereas the carcinoma models became far more sensitive to MEK inhibition. Increased sensitivity to MEK inhibition was also seen in MDA-MB-231 cells grown in 3D compared with 2D. In contrast, inhibition of phosphatidylinositol 3'-kinase activity by wortmannin had no significant effect on the growth of any of the cells in either 2D or 3D. Our conclusion is that 3D culture models may not only model the relative resistance of tumor cells to cytotoxic therapy but also that the 3D approach may better identify the driving oncogenic pathways and critical targeted inhibitors that may be effective treatment approaches.

Topics: Androstadienes; Antineoplastic Agents; Benzamides; Breast Neoplasms; Butadienes; Cell Culture Techniques; Cell Line; Cell Line, Transformed; Cell Line, Tumor; Cell Proliferation; Doxorubicin; Drug Resistance, Neoplasm; Female; Genes, ras; Humans; Hyperplasia; Mammary Glands, Human; Mitogen-Activated Protein Kinase Kinases; Nitriles; Phosphoinositide-3 Kinase Inhibitors; Wortmannin

Targeting MAPK kinase (MEK) in the MAPK pathway is a potentially effective therapeutic strategy for thyroid cancer.. The objective of the study was to investigate genotype-dependent therapeutic potential of the MEK inhibitor CI-1040 for thyroid cancer.. 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.. 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 microm, respectively, whereas the IC50 values for RET/PTC1-harboring TPC1 cells and the wild-type MRO and WRO cells were 44, 46, and 278 microm, 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.. 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.

Topics: Animals; Benzamides; Blotting, Western; Cell Line, Tumor; Cell Proliferation; Cyclin D1; DNA Fragmentation; Enzyme Inhibitors; Genes, ras; Humans; Hyperplasia; Mice; Mice, Nude; Mitogen-Activated Protein Kinase Kinases; Mutation; Proto-Oncogene Proteins B-raf; RNA; Thyroid Neoplasms; Xenograft Model Antitumor Assays