## 3 Discussion
Hsp90 is also augmented in various cancers, apparently playing important roles in cancer biology by regulating tumor growth, invasion, metastasis, angiogenesis, and apoptosis, and induces neoangiogenesis by stabilizing vascular endothelial growth factor and nitric oxide syntheses [38; 39; 40]. In light of what is available in the literature in the field of Hsp and cancer, very briefly summarized in the preceding paragraphs, we decided to evaluate the tissue levels of the four molecular chaperones discussed above, simultaneously, in samples of thyroid follicular neoplasms, about which there is little information. We also observed the localization of these Hsp in tumor cells to evaluate their possible localization change. Hsp27 levels did not show significant quantitative differences between the groups studied. This result is in contrast with the data present in the literature on other types of tumors, which indicates that the thyroid tumors deserve detailed analysis to elucidate the basis for this unique feature regarding Hsp27. However, even if we did not find a quantitative difference, we observed a nuclear localization that, according to the data in the literature, would be linked to the phosphorylation of the chaperone [41]. Conversely, we observed a higher immunopositivity of Hsp60, Hsp70, and Hsp90 in FC compared to FA and their adjacent parenchyma. These data are in agreement with what has been published in the literature on other types of tumors. The increase of Hsp60 and Hsp70 in FC suggest its implication in carcinogenesis and in the progression of this tumor. Hsp60 and Hsp70 levels in FC were higher compared to adjacent parenchyma levels. In normal cells, Hsp 60 is detected in the mitochondria while in tumoral cells it is abundant in the cytoplasm. These data are interesting because both Hsps could be considered tumor tissue markers. Likewise, the higher levels of Hsp90 might indicate its implication in the process of FC invasion of surrounding tissue. This could be attributed to the known stabilizing effects of Hsp90 on matrix metalloproteinases, which would favor tumor infiltration and invasion [42; 43]. In conclusion, our immunohistochemical data suggest an involvement of Hsp60, Hsp70, and Hsp90 in the mechanisms of carcinogenesis of thyroid follicular carcinoma. The immunomod morphological observation showed a change in cellular localization of the Hsps studied. This pattern is found in various carcinogenic processes [19; 24]. It is necessary to continue these studies to clarify the molecular mechanisms underlying the increase in tissue levels of these chaperones in this human cancer. In this regard, determination of chaperone-gene expression levels and elucidation of post-transcriptionalmechanisms that might be involved in augmenting the levels of the chaperones in thyroid tumors seem to be the most promising approaches toward finding points of attacks by anti-cancer agents. Conceptualization: C.C., F.C. and F.R. ; Methodology: A.P., L.P., S.D., S.M. ; Validation: D.C.; Investigation: A.P., G.G. ; Resources: A.M.V., L.P., S.M., A.F. ; Data Curation: F.C., F.R. ; Writing-Original Draft Preparation: F.R., A.M.V. ; Writing-Review & Editing, F.B., A.J.L.M. and E.C.deM. Supervision: A.J.L.M. and E.C.deM. A.J.L.M., and E.C.deM. were partially supported by IMET. This work was done under the agreement between IEMEST (Italy) and IMET (USA) (this is IMET contribution number IMET 19-016). The authors declare no conflict of interest.