Calcitriol stimulates gene expression of cathelicidin antimicrobial peptide in breast cancer cells with different phenotype.
BACKGROUND
In normal and neoplastic cells, growth-promoting, proangiogenic, cytotoxic and pro-apoptotic effects have all been attributed to cathelicidin antimicrobial peptide (CAMP). Nevertheless, little is known about the factors regulating this peptide expression in breast cancer. Herein we asked if the well-known antineoplastic hormone calcitriol could differentially modulate CAMP gene expression in human breast cancer cells depending on the cell phenotype in terms of efficacy and potency.


METHODS
The established breast cancer cell lines MCF7, BT-474, HCC1806, HCC1937, SUM-229PE and a primary cell culture generated from invasive ductal breast carcinoma were used in this study. Calcitriol regulation of cathelicidin gene expression in vitro and in human breast cancer xenografts was studied by real time PCR. Tumorigenicity was evaluated for each cell line in athymic mice.


RESULTS
Estrogen receptor (ER)α + breast cancer cells showed the highest basal CAMP gene expression. When incubated with calcitriol, CAMP gene expression was stimulated in a dose-dependent and cell phenotype-independent manner. Efficacy of calcitriol was lower in ERα + cells when compared to ERα- cells (<10 vs. >70 folds over control, respectively). Conversely, calcitriol lowest potency upon CAMP gene expression was observed in the ERα-/EGFR+ SUM-229PE cell line (EC50= 70.8 nM), while the highest was in the basal-type/triple-negative cells HCC1806 (EC50= 2.13 nM) followed by ERα + cells MCF7 and BT-474 (EC50= 4.42 nM and 14.6 nM, respectively). In vivo, lower basal CAMP gene expression was related to increased tumorigenicity and lack of ERα expression. Xenografted triple-negative breast tumors of calcitriol-treated mice showed increased CAMP gene expression compared to vehicle-treated animals.


CONCLUSIONS
Independently of the cell phenotype, calcitriol provoked a concentration-dependent stimulation on CAMP gene expression, showing greater potency in the triple negative HCC1806 cell line. Efficacy of calcitriol was lower in ERα + cells when compared to ERα- cells in terms of stimulating CAMP gene expression. Lower basal CAMP and lack of ERα gene expression was related to increased tumorigenicity. Our results suggest that calcitriol anti-cancer therapy is more likely to induce higher levels of CAMP in ERα- breast cancer cells, when compared to ERα + breast cancer cells.
Departamento de Biología de la Reproducción, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Avenida Vasco de Quiroga No. 15, Col. Belisario Domínguez Sección XVI, C.P., 14080, Ciudad de México, México.
Janice
J
García-Quiroz
Departamento de Biología de la Reproducción, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Avenida Vasco de Quiroga No. 15, Col. Belisario Domínguez Sección XVI, C.P., 14080, Ciudad de México, México.
Rocío
R
García-Becerra
Departamento de Biología de la Reproducción, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Avenida Vasco de Quiroga No. 15, Col. Belisario Domínguez Sección XVI, C.P., 14080, Ciudad de México, México.
Nancy
N
Santos-Martínez
Departamento de Biología de la Reproducción, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Avenida Vasco de Quiroga No. 15, Col. Belisario Domínguez Sección XVI, C.P., 14080, Ciudad de México, México.
Euclides
E
Avila
Departamento de Biología de la Reproducción, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Avenida Vasco de Quiroga No. 15, Col. Belisario Domínguez Sección XVI, C.P., 14080, Ciudad de México, México.
Fernando
F
Larrea
Departamento de Biología de la Reproducción, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Avenida Vasco de Quiroga No. 15, Col. Belisario Domínguez Sección XVI, C.P., 14080, Ciudad de México, México. lorenzadiaz@gmail.com.
Lorenza
L
Díaz
D000818:Animals; D023181:Antimicrobial Cationic Peptides; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D002117:Calcitriol / Q000008:administration & dosage*; D054804:Cathelicidins / Q000096:biosynthesis* / Q000235:genetics; D047628:Estrogen Receptor alpha / Q000235:genetics*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D061986:MCF-7 Cells; D051379:Mice; D023041:Xenograft Model Antitumor Assays
D023181:Antimicrobial Cationic Peptides; D054804:Cathelicidins; C506487:ESR1 protein, human; D047628:Estrogen Receptor alpha; D002117:Calcitriol
Breast cancer; Calcitriol; Cathelicidin; LL-37; Vitamin D