Calcium signalling and cancer cell growth

Two patients with Hailey-Hailey disease, multiple primary melanomas, and other cancers

BACKGROUND

Hailey-Hailey Disease (HHD) is an autosomal dominant skin disorder that is characterized by erythematous and sometimes vesicular, weeping plaques of intertriginous regions. Squamous cell carcinoma and basal cell carcinoma arising in lesions of HHD have been described in the literature. To our knowledge, there are no reports of melanoma or noncutaneous malignant neoplasms associated with HHD.

OBSERVATIONS

We discuss the mechanisms of oncogenicity, including genetic, environmental, and iatrogenic factors, in 2 patients with HHD, multiple primary melanomas, and other cancers. Patient 1 had a mucoepidermoid carcinoma of the parotid gland. Patient 2 had a history of acute monoblastic leukemia and malignant peripheral nerve sheath tumor as well as radiologic evidence of an acoustic neurilemmoma.

CONCLUSIONS

The cause of the cancers in these 2 patients is likely multifactorial. We describe the patients to draw attention to the possible association between HHD and cancer. Additional research should be performed to determine whether patients with HHD have an increased incidence of cancer.

Gene profiling of early and advanced liver disease in chronic hepatitis C patients

PURPOSE

Strong impact of hepatitis C virus (HCV) on normal regulation of cellular processes has been reported that could have significant implications for HCV pathogenesis. We aimed to determine the altered cellular processes during HCV infection with particular reference to advanced disease stages.

METHODS

Liver biopsy specimens of chronic hepatitis C patients classified on histological basis as early (fibrosis stage 1-2) or advanced (fibrosis stage 3-4) HCV disease were studied using microarray technology (Affymetrix GeneChip™ System). For comparison, liver specimens from patients with non-viral hepatitis (NV-hepatitis) were also analyzed by microarray. Expression data generated were analyzed using software Genespring GX and Ingenuity Pathway analysis to find the association with biological functions. We further validated the microarray results using quantitative reverse transcriptase-polymerase chain reaction.

RESULTS

Data analysis through Genespring software revealed that in advanced HCV (A-HCV) a total of 792 genes are differentially expressed when compared to early HCV (E-HCV) and 417 genes are differentially expressed when compared to NV-hepatitis. Most of these genes are involved in cancer, cellular growth and proliferation, and tissue morphology. Real time (RT) PCR analysis confirmed the differential expression of six of these genes.

CONCLUSION

The results of this study reflect the changes taking place during the transition from early to advanced liver fibrosis, when the liver function becomes impaired and extracellular matrix deposition increases. In addition, it showed altered expression of genes with functions in cancer development, cell growth, proliferation, and cell death that might indicate high risk of cell transformation and hepatocellular carcinoma (HCC) in A-HCV disease patients.

Down-regulation of Orai3 arrests cell-cycle progression and induces apoptosis in breast cancer cells but not in normal breast epithelial cells

Breast cancer (BC) is the leading cancer in the world in terms of incidence and mortality in women. However, the mechanism by which BC develops remains largely unknown. The increase in cytosolic free Ca(2+) can result in different physiological changes including cell growth and death. Orai isoforms are highly Ca(2+) selective channels. In the present study, we analyzed Orai3 expression in normal and cancerous breast tissue samples, and its role in MCF-7 BC and normal MCF-10A mammary epithelial cell lines. We found that the expression of Orai3 mRNAs was higher in BC tissues and MCF-7 cells than in normal tissues and MCF-10A cells. Down-regulation of Orai3 by siRNA inhibited MCF-7 cell proliferation and arrested cell cycle at G1 phase. This phenomenon is associated with a reduction in CDKs 4/2 (cyclin-dependent kinases) and cyclins E and D1 expression and an accumulation of p21(Waf1/Cip1) (a cyclin-dependent kinase inhibitor) and p53 (a tumor-suppressing protein). Orai3 was also involved in MCF-7 cell survival. Furthermore, Orai3 mediated Ca(2+) entry and contributed to intracellular calcium concentration ([Ca(2+)](i)). In MCF-10A cells, silencing Orai3 failed to modify [Ca(2+)](i), cell proliferation, cell-cycle progression, cyclins (D1, E), CDKs (4, 2), and p21(Waf1/Cip1) expression. Our results provide strong evidence for a significant effect of Orai3 on BC cell growth in vitro and show that this effect is associated with the induction of cell cycle and apoptosis resistance. Our study highlights a possible role of Orai3 as therapeutic target in BC therapy.

GeneBrowser 2: an application to explore and identify common biological traits in a set of genes

BACKGROUND

The development of high-throughput laboratory techniques created a demand for computer-assisted result analysis tools. Many of these techniques return lists of genes whose interpretation requires finding relevant biological roles for the problem at hand. The required information is typically available in public databases, and usually, this information must be manually retrieved to complement the analysis. This process is a very time-consuming task that should be automated as much as possible.

RESULTS

GeneBrowser is a web-based tool that, for a given list of genes, combines data from several public databases with visualisation and analysis methods to help identify the most relevant and common biological characteristics. The functionalities provided include the following: a central point with the most relevant biological information for each inserted gene; a list of the most related papers in PubMed and gene expression studies in ArrayExpress; and an extended approach to functional analysis applied to Gene Ontology, homologies, gene chromosomal localisation and pathways.

CONCLUSIONS

GeneBrowser provides a unique entry point to several visualisation and analysis methods, providing fast and easy analysis of a set of genes. GeneBrowser fills the gap between Web portals that analyse one gene at a time and functional analysis tools that are limited in scope and usually desktop-based.

Regucalcin is under-expressed in human breast and prostate cancers: Effect of sex steroid hormones

Regucalcin plays an important role in maintenance of intracellular Ca(2+) homeostasis, suppresses cell proliferation, inhibits expression of oncogenes, and increases the expression of tumour suppressor genes. This suggests that regucalcin functions may be altered in cancer tissues. In this study the regucalcin expression in breast and prostate cancer cases was analysed by RT-PCR and immunohistochemistry showing that the mRNA and/or protein are under-expressed in these tumors. The effect of sex steroid hormones on regucalcin expression in breast and prostate cancer cells was determined by real-time PCR. MCF-7 and LNCaP cells were stimulated with 0, 1, and 10 nM of 17beta-estradiol (E(2)) or 5alpha-dihydrotestosterone (DHT), respectively, for 0, 6, 12, 24, and 48 h. MCF-7 cells were also stimulated with E(2) conjugated to BSA (E(2)-BSA). To explore the mechanisms underlying the sex steroid regulation of regucalcin expression, control treatments with ICI 182,780, flutamide and cyclohexamide were carried out. E(2) effects regulating regucalcin expression were not abrogated in the presence of ICI 182,780, and were similar to those observed with E(2)-BSA, which suggests the involvement of a membrane-bound estrogen receptor. In LNCaP cells, DHT down-regulated regucalcin expression, an effect inhibited by the presence of both flutamide and cyclohexamide, suggesting the involvement of androgen receptor and de novo protein synthesis. The loss of regucalcin expression in breast and prostate cancer cases and the regulation of its expression by sex steroid hormones suggest that it may be associated with development and progression of these human tumors.

Vitamin D and calcium insufficiency-related chronic diseases: molecular and cellular pathophysiology

A compromised vitamin D status, characterized by low 25-hydroxyvitamin D (25-(OH)D) serum levels, and a nutritional calcium deficit are widely encountered in European and North American countries, independent of age or gender. Both conditions are linked to the pathogenesis of many degenerative, malignant, inflammatory and metabolic diseases. Studies on tissue-specific expression and activity of vitamin D metabolizing enzymes, 25-(OH)D-1 alpha-hydroxylase and 25-(OH)D-24-hydroxylase, and of the extracellular calcium-sensing receptor (CaR) have led to the understanding of how, in non-renal tissues and cellular systems, locally produced 1,25-dihydroxyvitamin D(3) (1,25-(OH)(2)D(3)) and extracellular Ca(2+) act jointly as key regulators of cellular proliferation, differentiation and function. Impairment of cooperative signalling from the 1,25-(OH)(2)D(3)-activated vitamin D receptor (VDR) and from the CaR in vitamin D and calcium insufficiency causes cellular dysfunction in many organs and biological systems, and, therefore, increases the risk of diseases, particularly of osteoporosis, colorectal and breast cancer, inflammatory bowel disease, insulin-dependent diabetes mellitus type I, metabolic syndrome, diabetes mellitus type II, hypertension and cardiovascular disease. Understanding the underlying molecular and cellular processes provides a rationale for advocating adequate intake of vitamin D and calcium in all populations, thereby preventing many chronic diseases worldwide.

Calcium-sensing receptor in cancer: good cop or bad cop?

The extracellular calcium-sensing receptor (CaR) is a versatile 'sensor' for di- and polycationic molecules in the body. CaR plays a key role in the defense against hypercalcemia by "sensing" extracellular calcium levels in the parathyroid and kidney, the key organs maintaining systemic calcium homeostasis. Although mutation of CaR gene has so far not been associated with any malignancy, aberrant functions of CaR have implications in malignant progression. One situation is loss of CaR expression, resulting in loss of growth suppressing effects of elevated extracellular Ca(2+) by CaR, reported in parathyroid adenoma and in colon carcinoma. Another situation is activation of CaR, resulting in increased production of parathyroid hormone-related peptide (PTHrP), a primary causal factor in hypercalcemia of malignancy and a contributor to metastatic processes involving bone. CaR signaling and effects have been studied in several cancers including ovarian cancers, gastrinomas, and gliomas in addition to comparatively detailed studies in breast, prostate, and colon cancers. Studies on H-500 rat Leydig cells, a xenotransplantable model of humoral hypercalcemia of malignancy has shed much light on the mechanisms of CaR-induced cancer cell growth and survival. Pharmacological agonists and antagonists of CaR hold therapeutic promise depending on whether activation of CaR is required such as in case of colon cancer or inactivating the receptor is required as in the case of breast- and prostate tumors.