## 3 Discussion  
In this work, we studied the immunohistochemical levels of Hps27, Hsp60, Hps70, and Hsp90 in human thyroid tissue with follicular adenoma (FA) and follicular carcinoma (FC). FC is characterized by the ability to invade the tumor capsule when this is present and forcing its way inside blood vessels and in the adjacent normal thyroid tissue. This characteristic distinguishes FC from FA. In general, the pathological condition of cancer is characterized by an imbalance between cell proliferation and differentiation. A physiological balance between cell proliferation and differentiation is essential to ensure proper growth and development of multicellular organisms, and to maintain adult tissue and organ homeostasis. It is of fundamental interest in cancer pathology to understand the mechanisms underpinning the origin of the loss of cell differentiation capability and the induction of malignancy progression. Molecular chaperones play a key role in the maintenance of cellular and tissue homeostasis and in the regulation of organ remodelling [20; 21; 22; 23]. However, when abnormal in structure and/or quantity and/or function, and/or location, chaperones can cause disease, the chaperopathies [7; 14], and numerous scientific reports showed their involvement in the pathogenesis and progression of various human neoplasms [15; 19; 24]. High tissue levels of Hsps are often associated with cancer progression and invasiveness, as shown by studies in which it was suggested that these proteins are augmented in some types of tumors with tendency to invade surrounding tissues and to spread to distant organs [19; 25; 26; 27]. Figure 4: Hsp90 Immunohistochemistry: (**A**) Representative images of immunohistochemical results for Hsp90. Magnification 200\(\times\); scale bar 100 \(\upmu\)m. (**B**) The histogram shows statistical results for the immunohistochemical evaluation for Hsp90 in follicular adenoma (FA), adjacent parenchyma of follicular adenoma (AP FA), follicular carcinoma (FC) and adjacent parenchyma of follicular carcinoma (AP FC). Data are presented as the mean +SD. * \(p\) < 0.05. Hsp27 was initially characterized as a chaperone that facilitates the refolding of damaged proteins in response to heat shock. Further investigations revealed that Hsp27 also responds to oxidative and chemical stressors, mainly acting as an antioxidant and antiapoptotic agent. It was observed that an increase of Hsp27 levels is transiently induced at specific stages during development and cell differentiation and occurs concomitantly with the differentiation-associated decrease of cellular proliferation [28; 29]. Other studies reported that Hsp27 is augmented in different types of tumors and its levels are directly associated with a more aggressive malignant behavior (cancer cell proliferation, invasiveness, and metastasis) and resistance to chemotherapy [30; 31]. Furthermore, Hsp27 mediates endothelial cell mobility, improving angiogenesis [32]. The eukaryotic Hsp60 resides and works in the mitochondrial matrix where, together with its co-chaperonin Hsp10, drives the proper folding of proteins destined to the mitochondrial matrix. In addition to this intramitochondrial function, Hsp60 plays a role in other cellular processes beyond the mitochondrion, for instance in the cytosol, plasma-cell membrane, extracellular environment, and biological fluids) [33]. Hsp60 seems to be directly or indirectly involved in carcinogenesis in different organs, since its levels change during the carcinogenic steps [15; 24]. Hsp60 levels are increased in various tumors such as colorectal cancer, liver and uterine cervical cancers and its levels are correlated with cancer progression, which makes this chaperonin a useful biomarker indicating poor prognosis [34; 35]. There are many reports of a strong association of Hsp70 with cancer development. For instance, it promotes carcinogenesis by acting as survival factor owing to its tumor-associated expression and anti-apoptotic effects [36]. Hsp70 abundance gives the neoplasm greater invasiveness [37].