Circadian rhythms at a central and peripheral level are operated by transcriptional/translational feedback loops involving a set of genes called ‘clock genes’ that have been implicated in the development of several diseases, including malignancies. Dysregulation of the Clock system can influence cancer susceptibility by regulating DNA damage and repair mechanisms, as well as apoptosis. A number of oncogenic pathways can be dysregulated via clock genes’ epigenetic alterations, including hypermethylation of clock genes’ promoters or variants of clock genes. Clock gene disruption has been studied in breast, lung and prostate cancer, and haematological malignancies. However, it is still not entirely clear whether clock gene disruption is the cause or the consequence of tumourigenesis and data in endocrine neoplasms are scarce. Recent findings suggest that clock genes are implicated in benign and malignant adrenocortical neoplasias. They have been also associated with follicular and papillary thyroid carcinomas and parathyroid adenomas, as well as pituitary adenomas and craniopharyngiomas. Dysregulation of clock genes is also encountered in ovarian and testicular tumours and may also be related with their susceptibility to chemotherapeutic agents. The most common clock genes that are implicated in endocrine neoplasms are PER1, CRY1; in most cases their expression is downregulated in tumoural compared to normal tissues. Although there is still a lot to be done for the better understanding of the role of clock genes in endocrine tumourigenenesis, existing evidence could guide research and help identify novel therapeutic targets aiming mainly at the peripheral components of the clock gene system.
Anna Angelousi, Eva Kassi, Narjes Ansari-Nasiri, Harpal Randeva, Gregory Kaltsas, and George Chrousos
K W Colston
María Rodríguez-Sanz, Daniel Prieto-Alhambra, Sonia Servitja, Natalia Garcia-Giralt, Laia Garrigos, Jaime Rodriguez-Morera, Joan Albanell, Maria Martínez-García, Iria González, Adolfo Diez-Perez, Ignasi Tusquets, and Xavier Nogués
The aim of the study was to evaluate the progression of bone mineral density (BMD) during 3 years of aromatase inhibitors (AI) therapy in actual practice conditions. This prospective, clinical cohort study of Barcelona–Aromatase induced Bone Loss in Early breast cancer (B-ABLE) assessed BMD changes during 3 years of AI treatment in women with breast cancer. Patients with osteoporosis (T score < −2.5 or T score ≤ −2.0) and a major risk factor and/or prevalent fragility fractures were treated with oral bisphosphonates (BPs). Of 685 women recruited, 179 (26.1%) received BP treatment. By the third year of AI therapy, this group exhibited increased BMD in the lumbar spine (LS; 2.59%) and femoral neck (FN; 2.50%), although the increase was significant only within the first year (LS: 1.99% and FN: 2.04%). Despite BP therapy, however, approximately 15% of these patients lost more than 3% of their baseline bone mass. At 3 years, patients without BP experienced BMD decreases in the LS (−3.10%) and FN (−2.79%). In this group, BMD changes occurred during the first (LS: −1.33% and FN: −1.25%), second (LS: −1.19% and FN: −0.82%), and third (LS: −0.57% and FN: −0.65%) years of AI treatment. Increased BMD (>3%) was observed in just 7.6% and 10.8% of these patients at the LS and FN, respectively. Our data confirm a clinically relevant bone loss associated with AI therapy amongst nonusers of preventative BPs. We further report on the importance of BMD monitoring as well as calcium and 25-hydroxy vitamin D supplementation in these patients.
D M Peehl and D Feldman
Prostate cancer is a leading cause of cancer-related deaths in many countries. Premalignant lesions and invasive cancer occur more frequently in the prostate than in any organ other than the skin. Yet, the incidence of clinically detected prostate cancer is much lower than the histopathological incidence. The slow growth of prostate cancer and the low incidence of clinically manifest disease in some geographical locations or racial/ethnic groups suggest that prostate cancer can be controlled, perhaps by dietary factors. Vitamin D and retinoids have emerged as leading candidates both to prevent and to treat prostate cancer. Many of the activities of these compounds, established from epidemiological studies, research with cell culture and animal models, and clinical trials, are consistent with tumor suppressor effects. However, retinoids may have additional tumor enhancer properties that balance or negate anti-cancer activity. This perhaps explains the overall lack of protective effects of vitamin A compounds against prostate cancer found in epidemiological studies, and the minimal efficacy of retinoids in clinical trials to treat prostate cancer. While current efforts focus on developing strategies to use vitamin D compounds to control prostate cancer, the possibility exists that prostate cancer cells may become resistant to tumor suppressor effects of vitamin D. Analyses of experimental model systems show that prostate cancer cells become less sensitive to vitamin D through loss of receptors or signaling molecules that mediate vitamin D's actions, or through changes in metabolic enzymes that synthesize or degrade vitamin D compounds. The potential promise of exploiting vitamin D to control prostate cancer is tempered by the possibility that prostate cancer, perhaps even at early stages, may develop mechanisms to escape tumor suppressor activities of vitamin D and/or retinoids.
G R Mundy and T A Guise
Tumors cause multiple effects on the skeleton and on calcium homeostasis, but they do so in specific patterns which are becoming better defined as the mediators responsible become more fully characterized. Metastatic bone disease occurs in the majority of patients with advanced cancer, and is particularly frequent in breast, lung and prostate cancers, which are the most common of all human tumors. Approximately 1,000 000 people die each year in Western Europe and the United States from these three malignancies, and the majority of these people have bone metastases. Bone is the third most common site of metastatic disease in tumors of all types and the second most common in breast and prostate cancer. In this review, the role of the tumor peptide parathyroid hormone-related peptide (PTH-rP) in the effects of cancer on the skeleton will be discussed.
Srilatha Swami, Aruna V Krishnan, Jasmaine Williams, Abhishek Aggarwal, Megan A Albertelli, Ronald L Horst, Brian J Feldman, and David Feldman
Obesity is an established risk factor for postmenopausal breast cancer (BCa), insulin resistance, and vitamin D deficiency, and all contribute to increased synthesis of mammary estrogens, the drivers of estrogen receptor-positive (ER+) BCa growth. As both dietary vitamin D and calcitriol treatments inhibit breast estrogen synthesis and signaling, we hypothesized that vitamin D would be especially beneficial in mitigating the adverse effects of obesity on ER+BCa. To assess whether obesity exerted adverse effects on BCa growth and whether vitamin D compounds could reduce these unfavorable effects, we employed a diet-induced obesity (DIO) model in ovariectomized C57BL/6 mice. Breast tumor cells originally from syngeneic Mmtv-Wnt1 transgenic mice were then implanted into the mammary fat pads of lean and obese mice. DIO accelerated the initiation and progression of the mammary tumors. Treatments with either calcitriol or dietary vitamin D reduced the adverse effects of obesity causing a delay in tumor appearance and inhibiting continued tumor growth. Beneficial actions of treatments with vitamin D or calcitriol on BCa and surrounding adipose tissue included repressed Esr1, aromatase, and Cox2 expression; decreased tumor-derived estrogen and PGE2; reduced expression of leptin receptors; and increased adiponectin receptors. We demonstrate that vitamin D treatments decreased insulin resistance, reduced leptin, and increased adiponectin signaling and also regulated the LKB1/AMPK pathway contributing to an overall decrease in local estrogen synthesis in the obese mice. We conclude that calcitriol and dietary vitamin D, acting by multiple interrelated pathways, mitigate obesity-enhanced BCa growth in a postmenopausal setting.
C Verdelli, L Avagliano, P Creo, V Guarnieri, A Scillitani, L Vicentini, G B Steffano, E Beretta, L Soldati, E Costa, A Spada, G P Bulfamante, and S Corbetta
Components of the tumour microenvironment initiate and promote cancer development. In this study, we investigated the stromal component of parathyroid neoplasia. Immunohistochemistry for alpha-smooth muscle actin (α-SMA) showed an abundant periacinar distribution of α-SMA+ cells in normal parathyroid glands (n=3). This pattern was progressively lost in parathyroid adenomas (PAds; n=6) where α-SMA+cells were found to surround new microvessels, as observed in foetal parathyroid glands (n=2). Moreover, in atypical adenomas (n=5) and carcinomas (n=4), α-SMA+ cells disappeared from the parenchyma and accumulated in the capsula and fibrous bands. At variance with normal glands, parathyroid tumours (n=37) expressed high levels of fibroblast-activation protein (FAP) transcripts, a marker of tumour-associated fibroblasts. We analysed the ability of PAd-derived cells to activate fibroblasts using human bone-marrow mesenchymal stem cells (hBM-MSCs). PAd-derived cells induced a significant increase in FAP and vascular endothelial growth factor A (VEGFA) mRNA levels in co-cultured hBM-MSCs. Furthermore, the role of the calcium-sensing receptor (CASR) and of the CXCL12/CXCR4 pathway in the PAd-induced activation of hBM-MSCs was investigated. Treatment of co-cultures of hBM-MSCs and PAd-derived cells with the CXCR4 inhibitor AMD3100 reduced the stimulated VEGFA levels, while CASR activation by the R568 agonist was ineffective. PAd-derived cells co-expressing parathyroid hormone (PTH)/CXCR4 and PTH/CXCL12 were identified by FACS, suggesting a paracrine/autocrine signalling. Finally, CXCR4 blockade by AMD3100 reduced PTH gene expression levels in PAd-derived cells. In conclusion, i) PAd-derived cells activated cells of mesenchymal origin; ii) PAd-associated fibroblasts were involved in tumuor neoangiogenesis and iii) CXCL12/CXCR4 pathway was expressed and active in PAd cells, likely contributing to parathyroid tumour neoangiogenesis and PTH synthesis modulation.
G A Clines and T A Guise
Calcium homeostasis is a tightly regulated process involving the co-ordinated efforts of the skeleton, kidney, parathyroid glands and intestine. Neoplasms can alter this homeostasis indirectly through the production of endocrine factors resulting in humoral hypercalcaemia of malignancy. Relatively common with breast and lung cancer, this paraneoplastic condition is most often due to tumour production of parathyroid hormone-related protein and ensuing increased osteoclastic bone resorption. Although control of hypercalcaemia is generally successful, the development of this complication is associated with a poor prognosis. The metastasis of tumour cells to bone represents another skeletal complication of malignancy. As explained in the ‘seed and soil’ hypothesis, bone represents a fertile ground for cancer cells to flourish. The molecular mechanisms of this mutually beneficial relationship between bone and cancer cells are beginning to be understood. In the case of osteolytic bone disease, tumour-produced parathyroid hormone-related protein stimulates osteoclasts that in turn secrete tumour-activating transforming growth factor-β that further stimulates local cancer cells. This ‘vicious cycle’ of bone metastases represents reciprocal bone/cancer cellular signals that likely modulate osteoblastic bone metastatic lesions as well. The development of targeted therapies to either block initial cancer cell chemotaxis, invasion and adhesion or to break the ‘vicious cycle’ is dependent on a more complete understanding of bone metastases. Although bisphosphonates delay progression of skeletal metastases, it is clear that more effective therapies are needed. Cancer-associated bone morbidity remains a major public health problem, and to improve therapy and prevention it is important to understand the pathophysiology of the effects of cancer on bone. This review will detail scientific advances regarding this area.
S Corbetta, L Vicentini, S Ferrero, A Lania, G Mantovani, D Cordella, P Beck-Peccoz, and A Spada
Previous studies indicate that nuclear factor kappaB (NF-κB) transcription factor is deregulated and overexpressed in several human neoplasias. The aim of this study was to test the hypothesis that the NF-κB pathway may be involved in parathyroid tumorigenesis. For this purpose, we determined the level of NF-κB activity, evaluated as phosphorylation of the transcription subunit p65, its modulation by specific and non-specific agents and its impact on cyclin D1 expression. Phosphorylated p65 levels present in parathyroid neoplasias (n = 13) were significantly lower than those found in normal tissues (n = 3; mean optical density (OD) 0.19 ± 0.1 vs 0.4 ± 0.1, P = 0.007), but there was no significant difference between adenomas and secondary and multiple endocrine neoplasia type 1 (MEN1)-related hyperplasia. Conversely, MEN2A (Cys634Arg)-related parathyroid samples showed extremely high levels of phosphorylated p65 that exhibited a nuclear localization at immunohistochemistry (n = 3). Phosphorylated p65 levels negatively correlated with menin expression (r2 = 0.42, P = 0.05). Tumor necrosis factor-α (TNFα) caused a significant increase in phosphorylated p65 levels (183 ± 13.8% of basal) while calcium sensing receptor (CaR) agonists exerted a significant inhibition (19.2 ± 3.3% of basal). Although TNFα was poorly effective in increasing cyclin D1 expression, NF-κB blockade by the specific inhibitor BAY11-7082 reduced FCS-stimulated cyclin D1 by about 60%. Finally, the inhibitory effects of CaR and BAY11-7082 on cyclin D1 expression were not additive – by blocking NF-κB CaR activation did not induce a further reduction in cyclin D1 levels. In conclusion, the study demonstrated that in parathyroid tumors: (1) p65 phosphorylation was dramatically increased by RET constitutive activation and was negatively correlated with menin expression, (2) p65 phosphorylation was increased and reduced by TNFα and CaR agonists respectively, and (3) blockade of the NF-κB pathway caused a significant decrease in cyclin D1 expression.
Luqman Sulaiman, Inga-Lena Nilsson, C Christofer Juhlin, Felix Haglund, Anders Höög, Catharina Larsson, and Jamileh Hashemi
In this study, we genetically characterized parathyroid adenomas with large glandular weights, for which independent observations suggest pronounced clinical manifestations. Large parathyroid adenomas (LPTAs) were defined as the 5% largest sporadic parathyroid adenomas identified among the 590 cases operated in our institution during 2005–2009. The LPTA group showed a higher relative number of male cases and significantly higher levels of total plasma and ionized serum calcium (P<0.001). Further analysis of 21 LPTAs revealed low MIB1 proliferation index (0.1–1.5%), MEN1 mutations in five cases, and one HRPT2 (CDC73) mutation. Total or partial loss of parafibromin expression was observed in ten tumors, two of which also showed loss of APC expression. Using array CGH, we demonstrated recurrent copy number alterations most frequently involving loss in 1p (29%), gain in 5 (38%), and loss in 11q (33%). Totally, 21 minimal overlapping regions were defined for losses in 1p, 7q, 9p, 11, and 15q and gains in 3q, 5, 7p, 8p, 16q, 17p, and 19q. In addition, 12 tumors showed gross alterations of entire or almost entire chromosomes most frequently gain of 5 and loss of chromosome 11. While gain of 5 was the most frequent alteration observed in LPTAs, it was only detected in a small proportion (4/58 cases, 7%) of parathyroid adenomas. A significant positive correlation was observed between parathyroid hormone level and total copy number gain (r=0.48, P=0.031). These results support that LPTAs represent a group of patients with pronounced parathyroid hyperfunction and associated with specific genomic features.