Calcium And the Risk of Cancers

Acute inflammatory proteins constitute the organic matrix of prostatic corpora amylacea and calculi in men with prostate cancer.

Department of Pathology, James Buchanan Brady Urological Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.

Corpora amylacea (CA) are a frequent microscopic finding in radical prostatectomy specimens from men undergoing treatment for prostate cancer. Although often observed histologically to be associated with inflammation, the contribution of CA to prostatitis-related symptoms of unknown etiology or to prostate carcinogenesis remains unclear. Prostatic calculi (PC), which potentially represent calcified forms of CA, are less common but can cause urological disease including urinary retention and prostatitis. We conducted a comprehensive compositional analysis of CA/PC to gain insight into their biogenesis. Infrared spectroscopy analysis of calculi collected from 23 patients confirmed a prevalence of calcium phosphate in the form of hydroxyapatite. This result sets PC apart from most urinary stones, which largely are composed of calcium oxalate. Tandem mass spectrometry-based proteomic analysis of CA/PC revealed that lactoferrin is the predominant protein component, a result that was confirmed by Western blot analysis. Other proteins identified, including calprotectin, myeloperoxidase, and alpha-defensins, are proteins contained in neutrophil granules. Immunohistochemistry (IHC) suggested the source of lactoferrin to be prostate-infiltrating neutrophils as well as inflamed prostate epithelium; however, IHC for calprotectin suggested prostate-infiltrating neutrophils as a major source of the protein, because it was absent from other prostate compartments. This study represents a definitive analysis of the protein composition of prostatic CA and calculi and suggests that acute inflammation has a role in their biogenesis–an intriguing finding, given the prevalence of CA in prostatectomy specimens and the hypothesized role for inflammation in prostate carcinogenesis.

PMID: 19202053 [PubMed – indexed for MEDLINE]

Calcium hydroxyapatite promotes mitogenesis and matrix metalloproteinase expression in human breast cancer cell lines.

Department of Clinical Pharmacology, Royal College of Surgeons in Ireland, Dublin, Ireland.

Radiographic mammary microcalcifications are one of the most pertinent diagnostic markers of breast cancer. Breast tissue calcification in the form of calcium hydroxyapatite (HA) is strongly associated with malignant disease. We tested the hypothesis that calcium HA may exert biological effects on surrounding cells, thereby facilitating breast cancer progression. Our findings showed that HA crystals enhanced mitogenesis in breast cancer cell lines MCF-7 and Hs578T and also in normal human mammary epithelial cells. HA crystals were also found to upregulate the production of a variety of matrix metalloproteinases (MMPs), including MMP-2, -9, and -13 in MCF-7 and MMP-9 in human mammary epithelial cell lines. HA crystals were found to greatly augment prostaglandin E(2) levels in Hs578T cells, and treatment with a cyclooxygenase inhibitor, aspirin, abrogated the HA-induced mitogenesis. These results suggest that calcium HA crystals may play an active role in amplifying the pathological process involved in breast cancer. Copyright 2001 Wiley-Liss, Inc.

PMID: 11746823 [PubMed – indexed for MEDLINE]

1: Breast Cancer Res Treat. 2003 May;79(2):253-63. Links

Phosphocitrate inhibits calcium hydroxyapatite induced mitogenesis and upregulation of matrix metalloproteinase-1, interleukin-1beta and cyclooxygenase-2 mRNA in human breast cancer cell lines.

Cooke MM, McCarthy GM, Sallis JD, Morgan MP.

Department of Clinical Pharmacology, Royal College of Surgeons in Ireland, Dublin, Ireland.

Microcalcifications containing calcium hydroxyapatite (HA) are often associated with malignant human breast lesions. Frequently, they are the only mammographic features that indicate the presence of a tumoural lesion. We previously reported the induction of both mitogenesis and prostaglandin E2 (PGE2) production and the increased activities of matrix metalloproteinases (MMPs) MMP-2 and MMP-9 in normal human mammary epithelial cells and breast cancer cell lines, treated with HA. In the present study we attempted to elucidate the mechanism of these biological effects. Firstly, we found that direct cell-crystal contact was required for induction of mitogenesis as the effect was not merely a result of isotopic exchange of calcium into the culture medium. Treatment with bafilomycin A1, a proton pump inhibitor, abrogated HA-induced mitogenesis to control cell levels. These results suggest that phagocytosis and intracellular crystal dissolution is required for HA-induced mitogenesis. We also demonstrated that the increase in prostaglandin E2, previously reported, is due, at least in part, to HA-induced upregulation of cyclooxygenase-2 (COX-2) in Hs578T cells. An accumulation of MMP-1 mRNA was also shown in response to HA stimulation in Hs578T cells. Furthermore, a HA-induced increase in interleukin-1beta (IL-1beta), a potent inducer of MMP-1 gene expression, was demonstrated in Hs578T cells at 2 and 4 h. Treatment with phosphocitrate (PC) (a naturally occurring inhibitor of calcium phosphate crystallisation, which is known to block a number of HA-induced biological effects in other cell types) blocked HA-mediated mitogenesis, as well as, COX-2, MMP-1 and IL-1beta induction, at the transcriptional level. These results show that calcium HA crystals are capable of exerting significant biological effects on surrounding cells which can be abrogated by PC and emphasise the role of calcium HA in amplifying the pathological process involved in breast cancer.

PMID: 12825860 [PubMed – indexed for MEDLINE]

Evidence that breast cancer associated microcalcifications are mineralized malignant cells.

Metastasis Research Laboratory, Tour de Pathologie, -1, Bat B23, Sart-Tilman, Liege, 4000, Belgium.

Microcalcifications are often associated with both benign and malignant human breast lesions. Around 40% of mammary carcinoma present such ectopic mineralization and frequently, they are the only mammographic feature that indicate the presence of a tumoral lesion. Microcalcifications associated with breast cancer are usually composed of hydroxyapatite, the bone specific mineral. The mechanisms responsible for the formation of such crystals within breast malignant tissue have not been elucidated. A possible clue could be provided by the recent demonstration that breast cancer cells express several bone matrix proteins including osteonectin, osteopontin and bone sialoprotein (BSP). This latter phospho-protein is involved in the initiation of hydroxyapatite crystallisation and its expression in breast cancer has been associated to the presence of hydroxyapatite microcalcifications. We examined 10 human breast cancer lesions which were characterized by the presence of microcalcifications and high expression of BSP. Histological examination of the lesions suggested, in most of the cases, that the microcalcifications were breast cancer cells which became mineralized. Hydroxyapatite stained in blue by hematoxylin appears concentrated around single of associated cancer cells. Staining of these tissue sections with 4′,6 diamidino-2-phenylindole which specifically labels DNA led us to demonstrate that the mineralizated structures contain cells. These data are the first direct demonstration that breast microcalcifications are fossils of cancer cells. The mechanisms for such a phenomenon remain to be demonstrated. We speculate that the high expression of BSP could create an appropriate microenvironment for the crystallisation of calcium and phosphate into hydroxyapatite.

1: Ultrastruct Pathol. 1984;6(1):9-14. Links

Intraluminal calcium hydroxyapatite crystals in breast carcinoma: an ultrastructural study.

Torell JA, Knight JP, Marcus PB.

Sixty-three breast carcinomas were examined by electron microscopy to determine the frequency of calcium hydroxyapatite (apatite) within tumor lumina. Twenty-one adenocarcinomas contained apatite in intracytoplasmic and/or intercellular lumina. Well-differentiated tumors exhibited a higher incidence of apatite (44%), while only 20% of the poorly differentiated tumors contained apatite (gamma = +.22). There was no apparent correlation between the presence of apatite and a positive estrogen receptor assay. Ninety-eight adenocarcinomas of other than breast origin (previously processed for electron microscopy) were examined, revealing 2 cases containing apatite in the appropriate locations. The tissue of origin in one case was determined to be ovarian, while the origin of the second case remains undetermined. The ultrastructural finding of apatite in lumina of adenocarcinoma appears to be unusual in that it has only been observed in breast carcinomas and certain ovarian tumors. The presence of apatite within the lumen in addition to other characteristics of an adenocarcinoma may suggest the breast as the primary site.

PMID: 6328717 [PubMed – indexed for MEDLINE]

Humoral bone morphogenetic protein 2 is sufficient for inducing breast cancer microcalcification.

Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.

Microcalcifications are an important diagnostic marker for breast cancer on mammograms, yet the mechanism of their formation is poorly understood. Indeed, there is presently no short-latency, high-yield, syngeneic rodent model of the process. Bone morphogenetic protein 2 (BMP-2) is a key mediator of physiologic bone formation and pathologic vasculature calcification, but its role in breast cancer microcalcification is unknown. In this study, R3230 rat breast tumors were adapted to cell culture, transduced with adenoviral BMP-2, and inoculated into a syngeneic host. Tumor growth and calcium salt deposition were quantified in living animals over time using micro-computed tomography and probed chemically using near-infrared fluorescence. Plasma BMP-2 levels were quantified over time by enzyme-linked immunosorbent assay. Within 3 weeks, 100% of the breast tumors developed microcalcifications, which were absent from all normal tissues. Importantly, when two tumors were initiated in a single host, the ipsilateral tumor expressing BMP-2 was able to induce microcalcification in the contralateral tumor that was not expressing BMP-2, suggesting that BMP-2 can act humorally. Taken together, we describe the first reproducible rodent model of breast cancer microcalcification, prove that BMP-2 expression is sufficient for initiating the process, and lay the foundation for a new generation of targeted diagnostic agents.

Dairy products, calcium and the risk of breast cancer: results of the French SU.VI.MAX prospective study.

INSERM U557, INRA U1125, CNAM EA3200, Université Paris 13, CRNH IdF, Unité de Recherche en Epidémiologie Nutritionnelle, Bobigny, France. e.kesse@uren.smbh.univ-paris13.fr

The aim was to estimate the association between dairy products (total and their subgroups), calcium intake and the risk of breast cancer. As few studies have considered menopausal status, we also investigated stratified analyses. This analysis included 3,627 women from the French SU.VI.MAX study, among whom 92 developed breast cancer during the follow-up period. Food consumption was assessed based on five 24-hour records completed during the previous 18 months to follow-up. Calcium intake was calculated using an ad-hoc food composition database. Cox proportional hazards models were used to estimate relative risk (RR), comparing 4th quartile vs. 1st quartile, and 95% confidence intervals (95% CI). A lower risk of breast cancer was observed with high total dairy product consumption in the whole population (RR = 0.55, 95% CI = 0.29-1.03, p(trend) = 0.03) and among premenopausal women with a RR of 0.35 (95% CI = 0.12-0.95, p(trend) = 0.01). None of these associations remained after control for calcium intake. Increasing calcium intake was inversely associated with breast cancer risk considering the whole population (RR = 0.50, 95% CI = 0.27-0.91, p(trend) = 0.04) and among the subgroup of premenopausal women (RR = 0.26, 95% CI = 0.10-0.71, p(trend) = 0.01) respectively. Our data support the hypothesis that dairy products, through calcium content or a correlated component, might have a negative association with the risk of breast cancer, particularly among premenopausal women. Copyright 2007 S. Karger AG, Basel.

Extracellular calcium promotes the migration of breast cancer cells through the activation of the calcium sensing receptor.

INSERM ERI-12 EA 4292, University of Picardie Jules Verne, 1 Rue des Louvels, Amiens 80037, France. zuzana.saidak@u-picardie.fr

Breast cancer is the most frequent form of cancer in women, with the highest incidence of metastasis to the bone. The reason for the preferential destination to the bone is believed to be due to chemoattractant factors released during bone resorption, which act on the cancer cells facilitating their metastasis. One of the factors released during osteolysis that may mediate breast cancer bone localization is Ca2+. Here, we show that extracellular Ca2+ (Ca2+(o)) acting via the calcium-sensing receptor (CaSR), greatly promotes the migration of bone-preferring breast cancer cells. In Boyden Chamber and Scratch Wound migration assays, an increase in breast cancer cell migration was observed at 2.5 mM and 5 mM Ca2+(o) compared to basal levels for three of the four breast cancer cell lines tested. However, a significantly greater migratory response was observed for the highly bone metastatic MDA-MB-231 cells, compared to the MCF7 and T47D, which have a lower metastatic potential in vivo. The BT474 cells, which do not metastasize to the bone, did not respond to elevated concentrations of Ca2+(o) in the migration assays. Inhibition of either ERK1/2 MAPK or phospholipase Cbeta (PLCbeta) led to an abolition of the Ca2+(o)-induced migration, implicating these pathways in the migratory response. Knockdown of the CaSR by siRNA resulted in an inhibition of the Ca2+(o)-induced migration, demonstrating the involvement of this receptor in the effect. These results suggest that the activation of the CaSR by elevated Ca2+(o) concentrations, such as those found near resorbing bone, produces an especially strong chemoattractant effect on bone metastatic breast cancer cells toward the Ca2+-rich environment.

PMID: 19285978 [PubMed – indexed for MEDLINE

Vitamin D and calcium intake in relation to risk of endometrial cancer: a systematic review of the literature.

Epidemiology and Surveillance Research, American Cancer Society, 1599 Clifton Rd NE, Atlanta, GA 30329, USA. marji.mccullough@cancer.org

OBJECTIVE: In response to a recent ecologic study of UV exposure and endometrial cancer incidence, we present the epidemiologic evidence on the relation between intake of vitamin D and its metabolically related nutrient, calcium, and the occurrence of endometrial cancer. METHODS: We conducted a systematic literature review and meta-analysis of vitamin D and calcium in relation to endometrial cancer, including peer-reviewed manuscripts published up to May 2007. Random and fixed effects summary estimates were computed. RESULTS: Pooled analyses of the three case-control studies of dietary vitamin D and endometrial cancer uncovered heterogeneous results that were not significant in random or fixed effects analyses. Cut-points for the highest vitamin D intakes ranged from >244 to >476 IU/day. Qualitatively similar findings were observed for dietary calcium. Only two studies provided estimates for calcium supplements (random effects OR=0.62, 95% CI 0.39-0.99; fixed effects OR=0.62, 95% CI 0.42-0.93, for top vs. bottom category, p for heterogeneity=0.25). CONCLUSIONS: The limited epidemiological evidence suggests no relation between endometrial cancer in the ranges of dietary vitamin D examined, and suggests a possible inverse association for calcium from supplements. Prospective studies, ideally including plasma 25(OH) D to estimate vitamin D input from diet and sun exposure, are needed to further explore these hypotheses.

PMID: 18155758