You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Chemical"].

Please return the output as a JSON object of the format: {"Chemical": ["Arsenic", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

SNAIL Induces Epithelial-to-Mesenchymal Transition and Cancer Stem Cell-like Properties in Aldehyde Dehydroghenase-Negative Thyroid Cancer Cells. Background: Epithelial-to-mesenchymal transition (EMT) has been thought to play a critical role in invasion and metastasis of cancer and to be associated with cancer stem cell (CSC) properties. It is not clear if there is a link between EMT and CSCs in thyroid cancers. We therefore investigated CSC properties of thyroid cancers that underwent EMT. Method: To induce EMT (spindle-like cell morphology, loss and acquisition of expression of an epithelial marker E-cadherin and a mesenchymal marker vimentin, respectively) in an epithelial type thyroid cancer cell line ACT-1, we used transforming growth factor-beta (TGF-beta), BRAFV600E and/or Snail homolog 1 (SNAI1, also known as SNAIL) . CSC properties were analyzed with assays for cell proliferation, chemosensitivity, in vitro and in vivo tumor formation ability, cell surface antigens and intracellular aldehyde dehydrogenase (ALDH; a known CSC marker) activities. Results: EMT was induced most efficiently by SNAIL (ACT-SNAIL cells), whereas TGF-beta and BRAFV600E were less efficient. ACT-SNAIL cells showed slightly but significantly enhanced tumor formation ability in in vitro sphere assay (~3 fold) but not in vivo subcutaneous tumor growth assay, and showed comparable chemosensitivity, as compared to the parental ACT-1 cells. However, of interest, although in vitro sphere formation ability of ALDH+ cells was almost unchanged after SNAIL induction, SNAIL overexpression induced much higher (~14 fold) spheres in ALDH- cells. Thus, ALDH was no longer a CSC marker in ACT-SNAIL cells. Conclusions: All these data indicate that EMT confers CSC properties in ALDH- cells and appears to influence the ability of ALDH to enrich CSCs.
{"Chemical": ["aldehyde", "Aldehyde"]}