SP600125 has a remarkable anticancer potential against undifferentiated thyroid cancer through selective action on ROCK and p53 pathways

Thyroid cancer is the most common endocrine malignancy with increasing incidence worldwide. The majority of thyroid cancer cases are well differentiated with favorable outcome. However, undifferentiated thyroid cancers are one of the most lethal human malignancies because of their invasiveness, metastatization and refractoriness even to the most recently developed therapies. In this study we show for the first time a significant hyperactivation of ROCK/HDAC6 pathway in thyroid cancer tissues, and its negative correlation with p53 DNA binding ability. We demonstrate that a small compound, SP600125 (SP), is able to induce cell death selectively in undifferentiated thyroid cancer cell lines by specifically acting on the pathogenic pathways of cancer development. In detail, SP acts on the ROCK/HDAC6 pathway involved in dedifferentiation and invasiveness of undifferentiated human cancers, by restoring its physiological activity level. As main consequence, cancer cell migration is inhibited and, at the same time, cell death is induced through the mitotic catastrophe. Moreover, SP exerts a preferential action on the mutant p53 by increasing its DNA binding ability. In TP53-mutant cells that survive mitotic catastrophe this process results in p21 induction and eventually lead to premature senescence. In conclusion, SP has been proved to be able to simultaneously block cell replication and migration, the two main processes involved in cancer development and dissemination, making it an ideal candidate for developing new drugs against anaplastic thyroid cancer.


SP600125
has a remarkable anticancer potential against undifferentiated thyroid cancer through selective action on ROCK and p53 pathways

Supplementary Material
Cell lines NTHY-ORI 3-1 cell line was originally obtained from normal human primary thyroid follicular epithelial cells transfected with a plasmid containing an origin-defective large T antigen SV40 genome. They express thyroid epithelial specific features, such as iodide-trapping and thyroglobulin production; Although they acquired growth factor-independency they remain non-tumorigenic in nude mice [1]. NTHY-ORI 3-1 presents diploid status with additional tetraploid clones together with very low frequency of spindle abnormalities and normal centrosomes [2]. They do not present common thyroid carcinoma genetic alterations.
TPC1 cells are derived from a papillary thyroid cancer [3]. TPC1 cells presents diploid status together with an additional minor tetraploid clone with very low frequency of spindle abnormalities and normal centrosomes [2,4]. They express the thyroid specific transcription factors PAX8, TTF1 and TTF2 [4][5].
presents mainly tetraploid status with with very low frequency of spindle abnormalities and normal centrosomes [2].
HTC/C3 were derived from cancer cells disseminated in the pleural fluid of a 44-year-old woman with a PTC-derived undifferentiated thyroid carcinoma highly resistant to chemotherapy [13]. They secrete IL1α, TGFα and PTH-like substance and have lost responsiveness to TSH; they have near-triploid karyotype with 23% polyploidy [13]. HTC/C3 express high levels of EGFR, they have heterozygous BRAF V600E , TERT promoter pathogenic mutation, p53 p.P152L point mutation and wild type status of RET, K-RAS, N-RAS and CTNNB1 [9,[14][15].
SW579 are derived from a squamous cell carcinoma of thyroid origin from a 59-year old caucasian male [16][17]. They have p53 p.I255S point mutation and wild type status of BRAF, RET, K-RAS, N-RAS and CTNNB1 [14].
FRO are derived from a patient with a large cell undifferentiated thyroid carcinoma [18]. Although they have WT TP53 they have a markedly decreased p53 mRNA content and do not express p53 at protein level [18][19]. They express high levels of p27 and cyclin D3, intermediate to low levels of PTEN and harbour BRAF V600E variant and CDKN2A c.238C>T nonsense mutation causing premature stop codon [15,[20][21][22]. SW1736 were established from an anaplastic thyroid cancer of a female patient. They have undetectable levels of TTF1 but high expression of several stem markers, like SOX2, OCT4, NANOG, C-MYC, SSEA4, and the ABCG2 transporter [23][24]. They harbour a heterozygous BRAF V600E variant, TERT promoter pathogenic point mutation and have wild status for RET and PI3K [7,9,[25][26]. Moreover they do not express p53 at protein level and express high levels of Δnp73α [20,[27][28].