ABSTRACT
BACKGROUND & AIMS: High concentration of 1,25(OH)2D3 (50-100 nM), which cause hypercalcemia in vivo, induce the hormone transcriptional targets and exert antiproliferative effects in cultured breast cancer lineages, however, no studies investigated whether these effects might be reproduced in tumor specimens in vivo. Our aim was to evaluate the effects of calcitriol supplementation on the proliferative index (Ki67 expression) and gene expression profile of post-menopausal breast cancer samples. METHODS & RESULTS: Tumor samples were collected from 33 patients, most of whom (87.5%) presenting 25(OH)D3 insufficiency, before and after a short term calcitriol supplementation (0.50 µg/day PO, for 30 days). Tumor dimension remained stable in ultrasound evaluations. A slight reduction in Ki67 immunoexpression was detected, however in only 10/32 post-calcitriol samples an expressively low proliferative index [Ln (%Ki67+) < 1] was achieved. Gene expression from 15 matched pre/post-supplementation samples was analyzed by microarray (U133 Plus 2.0 GeneChip, Affymetrix) and 15 genes were over-expressed in post-supplementation tumors, including FOS and EGR1, which were previously shown to be regulated by vitamin D. However, these results were not confirmed in another four breast cancer samples. CONCLUSIONS: Calcitriol supplementation is neither sufficient to expressively elicit an antiproliferative response nor to induce the hormone transcriptional signaling pathway in breast cancer specimens.
Subject(s)
Breast Neoplasms/metabolism , Calcitriol/administration & dosage , Dietary Supplements , Ki-67 Antigen/metabolism , Transcriptome , Aged , Aged, 80 and over , Breast Neoplasms/genetics , Case-Control Studies , Cell Proliferation/drug effects , Early Growth Response Protein 1/genetics , Early Growth Response Protein 1/metabolism , Female , Humans , Ki-67 Antigen/genetics , Middle Aged , Oncogene Proteins v-fos/genetics , Oncogene Proteins v-fos/metabolism , Postmenopause , Signal TransductionABSTRACT
Pacientes com câncer de mama apresentam menores níveis de 1,25(OH)2D3 ou 25(OH)D3 em relação às mulheres sem a doença. Embora linhagens de câncer de mama apresentem inibição do crescimento em concentrações supra-fisiológicas de 1,25(OH)2D3, forma ativa da vitamina D, ainda não se demonstrou se o hormônio exerce efeito antiproliferativo, em concentrações fisiológicas, em tumores de seres humanos. A suplementação de calcitriol pode ser indica a mulheres pós-menopausadas para prevenir a perda óssea. Nosso objetivo foi avaliar em pacientes com câncer de mama, pós menopausadas, a dimensão do tumor, taxa de proliferação (expressão de Ki67), concentração sérica de 1,25(OH)2D3 e 25(OH)D3, expressão gênica tumoral do receptor de vitamina D (VDR) e alguns genes alvos como, CYP24A1, CYP27B1, IGFBP3, PHB, TGFB2, CDKN1A, CDKN1B, CYP27B1, MYC, CAMP, TXNRD2, antes a após um mês de suplementação oral de calcitriol. Foram estudadas 24 pacientes com doença operável, idade mediana de 57 anos. As primeiras 10 pacientes e as 14 seguintes receberam 0,25 e 0,50g/dia de calcitriol, respectivamente, por um período mediano de 31 dias. Três quartos das pacientes apresentavam nível sérico de insuficiência de 25(OH)D3 ou insuficiência relativa (<30ng/ml) e após a suplementação, nenhuma paciente apresentou elevação dos níveis séricos de 1,25(OH)2D3 e 25(OH)D3. Embora a dimensão tumoral, mensurada por ultrasonografia, não apresentasse variação, a imuno-expressão de Ki67 sofreu um redução relativa mediana de 40%. A expressão relativa de VDR, CYP24A1, CYP27B1, IGFBP3, PHB, TGFB2, CDKN1A, CDKN1B, CYP27B1, MYC, CAMP, TXNRD2 não se alterou com a suplementação. Nossos dados indicam que tumores de mama expressam VDR, e que após suplementação oral de calcitriol, ocorre uma redução da proliferação. Este efeito merece ser elucidado, desde que genes alvo clássicos da 1,25(OH)2D3 não parecem ser mediadores do efeito anti-proliferativo, em amostras de câncer de mama de pacientes pós menopausadas.
Breast cancer patients present lower 1,25(OH)2D3 or 25(OH)D3 serum levels than unaffected women. Although breast cancer cell lines are growth inhibited by vitamin D supra-physiological concentrations, there is much uncertainty about the anti-proliferative effect of physiological concentrations of 1,25(OH)2D3, the active form of vitamin D, in breast cancer specimens in vivo. Vitamin D supplementation to post-menopausal women may be indicated to reduce bone loss. Our aim was to evaluate tumor dimension, proliferation rate (Ki67 expression), 25(OH)D3 and 1,25(OH)2D3 serum concentration, and tumor expression of vitamin D receptor (VDR), and of some target genes as CYP24A1, CYP27B1, IGFBP3, PHB, TGFB2, CDKN1A, CDKN1B, CYP27B1, MYC, CAMP, TXNRD2, before and after a one month calcitriol supplementation to post-menopausal breast cancer patients. Twenty four patients with operable disease, median age 57 years, were enrolled. The first tem patients were supplemented with calcitriol 0.25g/d and the next 14 patients, with 0.50g/d, for a median period of 31 days. Three fourths of the patients presented 25(OH)D3 insufficiency or relative insufficiency (<30 ng/mL) and after calcitriol supplementation, none of them presented an elevation of 1,25(OH)2D3 or 25(OH)D3 serum concentration. Although tumor dimension, evaluated by ultrasonography, did not vary, a median relative reduction of 40% in Ki67 immuno-expression, was observed. No differences in VDR, CYP24A1, CYP27B1, IGFBP3, PHB, TGFB2, CDKN1A, CDKN1B, CYP27B1, MYC, CAMP, TXNRD2 mRNA relative expression were detected between pre and post-supplementation samples. No differences in VDR, CYP27B1 and CYP24A1 tumor relative expression were detected following supplementation. Our data indicate that VDR expression is detected in breast cancer samples and that growth inhibition takes place after calcitriol oral supplementation. This anti-proliferative effect deserves further investigation, as classical target genes do not...
