Primary hyperparathyroidism (pHPT) is a common endocrinopathy resulting from inappropriately high PTH secretion. It usually results from the presence of a single gland adenoma, multiple gland hyperplasia or rarely parathyroid carcinoma. All these conditions require different management, and it is important to be able to differentiate the underlined pathology, in order for the clinicians to provide the best therapeutic approach. Elucidation of the genetic background of each of these clinical entities would be of great interest. However, the molecular factors that control parathyroid tumorigenesis are poorly understood. There are data implicating the existence of specific genetic pathways involved in the emergence of parathyroid tumorigenesis. The main focus of the present study is to present the current optimal diagnostic and management protocols for pHPT as well as to review the literature regarding all molecular and genetic pathways that are to be involved in the pathophysiology of sporadic pHPT.

Primary hyperparathyroidism (PHPT) is defined by inappropriate elevation of parathormone, caused by parathyroid hyperplasia, also known as multi-gland disease (MGD), parathyroid adenoma (PA), or parathyroid carcinoma (PC). Although several studies have already been conducted, there is a lack of a definite diagnostic marker, which could unambiguously distinguish MGD from PA or PC. The accurate and prompt diagnosis has the key meaning for effective treatment and follow-up. This review paper presents the role of apoptosis in PHPT. The comparison of the expression of Fas, TRAIL, BCL-2 family members, p53 in MGD, PA, and PC, among others, was described. The expression of described factors varies among proliferative lesions of parathyroid gland; therefore, these could serve as additional markers to assist in the diagnosis.

This review focuses on the pathologic entities associated with hyperparathyroidism in humans. A discussion of the lesions, their embryology, and pathologic features is included. Immunohistology, cytopathology, and a brief overview of molecular aspects of the lesion are included.

AZGP1 is a multifaceted protein associated with lipid mobilization, a process that is regulated by FASN and other metabolic pathways such as mTOR signaling. The active mTOR signaling pathway has been found to be involved in a variety of tumors. However, it remains unclear whether it is involved in the regulation of AZGP1 and FASN. An AZGP1-expressing plasmid was transfected into a human colorectal cancer cell line (LoVo) with a low expression of AZGP1. The expression of AZGP1, FASN, eIF4E, p-mTOR, p-S6,and S6K1 were measured by Western blot analysis, and target genes were detected by RT-PCR. Cell proliferation was studied using the MTT and colony formation assays. The analysis of apoptosis and the cell cycle phase were assessed by flow cytometry. The capacity of cell migration was investigated using the transwell migration assay. We found that the expression of AZGP1 was up-regulated while the expression of FASN, eIF4E, p-mTOR, p-S6, and S6K1 were down-regulated in LoVo cells after AZGP1 was expressed. The proliferation of malignant cells was reduced in AZGP1-overexpression cells, which is consistent with an increased in the G2-arrest and apoptosis rate. Furthermore, the migration of AZGP1-overexpression cells was decreased. The overexpression of AZGP1 suppressed the activation of the mTOR pathway and endogenous FASN-regulated fatty acid synthesis, mitigating the malignant phenotype of LoVo cells. Herein, we provide evidence that AZGP1 may constitute a novel tumor suppressor for LoVo colorectal cancer cells.

Cells under hypoxic stress either activate an adaptive response or undergo cell death. Although some mechanisms have been reported, the exact mechanism behind hypoxic cell death remains unclear. Recently, increased expression of fatty acid synthase (FASN) has been observed in various human cancers. In highly proliferating cells, tumor-associated FASN is considered necessary for both membrane lipids production and post-translational protein modification, but the exact mechanisms are not fully understood. Further, FASN overexpression is associated with aggressive and malignant cancer diseases and FASN inhibition induces apoptosis in cancer cells. For this reason, FASN is emerging as a key target for the potential diagnosis and treatment of various cancers. Here, we observed decreased FASN expression under hypoxic cell death conditions in HepG2 cells. Thus, we examined the effect of decreased FASN expression on hypoxia-induced cell death in HepG2 cells and also investigated the mechanism responsible for reduction of FASN expression under hypoxic cell death conditions. As a result, reduction of FASN expression resulted in hypoxic cell death via malonyl-CoA accumulation. In addition, SREBP-1 restored FASN reduction and hypoxia-induced apoptosis. Taken together, we suggest that hypoxic cell death is promoted by the reduced expression of FASN through SREBP-1 down-regulation.

While normal tissues are tightly regulated by nutrition and a carefully balanced system of glycolysis and fatty acid synthesis, tumor cells are under significant evolutionary pressure to bypass many of the checks and balances afforded normally. Cancer cells have high energy expenditure from heightened proliferation and metabolism and often show increased lipogenesis. Fatty acid synthase (FASN), the enzyme responsible for catalyzing the ultimate steps of fatty acid synthesis in cells, is expressed at high levels in tumor cells and is mostly absent in corresponding normal cells. Because of the unique expression profile of FASN, there is considerable interest not only in understanding its contribution to tumor cell growth and proliferation, but also in developing inhibitors that target FASN specifically as an anti-tumor modality. Pharmacological blockade of FASN activity has identified a pleiotropic role for FASN in mediating aspects of proliferation, growth and survival. As a result, a clearer understanding of the role of FASN in tumor cells has been developed.

The aim of the paper was to apply a method for quantitative assessment of proliferation and apoptosis markers, based on their 3D visualization, in cases of parathyroid adenoma and hyperplasia. Material was obtained from 49 patients (32 females and 17 males) with primary hyperparahyroidism. Quantitative immunohistochemistry studies of Ki-67, proliferating cell nuclear antigen (PCNA) and bcl-2 were performed on digital microscopy images with the use of 3D visualization. The use of spatial visualization method allowed us to perform objective quantitative assessment of the studied immunohistochemical markers. The average cell nuclear fraction of Ki67+ was 1.8% in hyperplasia and 1.9% in adenoma cases while 3.5% in the controls. The highest expression of PCNA was found in parathyroid hyperplasia (22.9%) and significantly decreased in adenoma (12.5%) and in the control group (16.8%). The lower expression of bcl-2 in hyperplasia cases (mean area fraction of 0.172 per 1 mum(2), in contrast to 0.643 in adenomas and 0.648 in control) suggested that principal cells can be ready for apoptosis and may confirm the important role of bcl-2 protein in etiopathogenesis of hyperplasia of the parathyroid gland while PCNA might be a useful marker for differentiating adenoma from early hyperplasia in primary hyperparahyroidism cases.

We explored the immunohistochemical expression of fatty acid synthase (FAS) in Paget's disease of the vulva (PDV) and its association with clinico-pathological features. FAS is a recently discovered molecule involved in energy supply of normal cells. FAS is also overexpressed in neoplastic tissues because of their increased necessity of energy. Specimens from 20 patients with PDV were immunohistochemically evaluated; increased FAS expression was observed in 7 of 8 patients with invasive PDV (87%), in 3 of 4 patients with microinvasive PDV (75%), and in 1 of 8 patients with noninvasive PDV (12%). Statistical analysis revealed that increased FAS expression was associated with invasive PDV (p = 0.04). To our knowledge, this association of FAS in PDV is the first to be reported in literature. These observations reveal that FAS is a reliable marker of aggressiveness in PDV. The knowledge of FAS statistical association in invasive PDV is an important finding that may stratify these patients in different prognostic groups and determine therapeutic approaches for patient care.

In renal hyperparathyroidism, parathyroid cell proliferation seems to play a key role in the progression of the disease. Therefore, G1/S transition, a main cell cycle regulatory step, could be deregulated in these patients.

One hundred and one parathyroid glands, taken from parathyroidectomies performed on 41 patients on hemodialysis (HD), and 15 glands, taken from 7 patients with post-transplantation persistent hyperparathyroidism (HPT), were studied. Twelve normal parathyroid (PT) glands were used as the control. Biochemical data, immunohistochemical (IHC) profiles of G1/S transition regulators belonging to the two main pathways (cyclin D1/p16INK4A/pRb and p14ARF/p53/MDM2), and proliferation rate (Ki67) were correlated.

All of the other proteins differed from normal IHC profiles in both groups that showed significant higher proliferating rates, decreases in p27KIP1, pRb, and cyclin D1, as well as increases in p16INK4A, p53, MDM2, and p21WAF1 levels, in comparison with normal PT glands, with the exception of cyclin D3. Contrary to patients with HPT who were on hemodialysis, in post-transplantation HPT, consistent correlations between biochemical data and IHC profiles were obtained.

In both groups IHC profiles of proteins involved in G1/S transition regulation significantly differed from normal PT glands. The results support partial reversion to normal IHC profile in post-transplantation HPT.

To evaluate the immunohistochemical expression of GLUT1, human erythrocyte glucose transporter 1, and fatty acid synthase (FAS), 66 human breast carcinomas and adjacent peritumoral tissue were studied. GLUT1 and FAS were expressed in 53 and 61 carcinomas, in 17 and 14 typical/atypical hyperplastic tissues, and in 16 and 13 tissues adjacent to tumor normal breast tissue, respectively. Statistical analysis revealed association between invasive carcinomas, invasive carcinomas with in situ component and GLUT1 immunostaining. GLUT1 staining was associated with tumor grade, FAS with tumor stage, and GLUT1 and FAS coexpression with tumor grade. Controls expressed no immunostaining. GLUT1 and FAS are new markers involved in the biologic activities of cancer cells. GLUT1 and FAS coexpression may indicate increased use of energy by the neoplastic cells correlated with poorly differentiated features and aggressive behavior. The innovative finding that GLUT1 and FAS are observed in mammary carcinoma adjacent nonneoplastic tissues may suggest a role in detecting initial phases of breast carcinogenesis.