The main objective of this study was to analyze changes in the antiproliferative effect of vitamin D3, in the form of calcitriol and calcidiol, via its combined application with all-trans retinoic acid (ATRA) in osteosarcoma cell lines. The response to treatment with calcitriol and calcidiol alone was specific for each cell line. Nevertheless, we observed an enhanced effect of combined treatment with ATRA and calcitriol in the majority of the cell lines. Although the levels of respective nuclear receptors did not correlate with the sensitivity of cells to these drugs, vitamin D receptor (VDR) upregulation induced by ATRA was found in cell lines that were the most sensitive to the combined treatment. In addition, all these cell lines showed high endogenous levels of retinoic acid receptor α (RARα). Our study confirmed that the combination of calcitriol and ATRA can achieve enhanced antiproliferative effects in human osteosarcoma cell lines in vitro. Moreover, we provide the first evidence that ATRA is able to upregulate VDR expression in human osteosarcoma cells. According to our results, the endogenous levels of RARα and VDR could be used as a predictor of possible synergy between ATRA and calcitriol in osteosarcoma cells.

• Klíčová slova
• all-trans retinoic acid, calcidiol, calcitriol, osteosarcoma, retinoic acid receptor α, vitamin D receptor,
• MeSH
• alfa receptor kyseliny retinové metabolismus   MeSH
• kalcifediol aplikace a dávkování   MeSH
• kalcitriol aplikace a dávkování   MeSH
• lidé MeSH
• nádorové buněčné linie MeSH
• osteosarkom farmakoterapie   metabolismus   MeSH
• protinádorové látky aplikace a dávkování   MeSH
• protokoly protinádorové kombinované chemoterapie MeSH
• receptory kalcitriolu metabolismus   MeSH
• screeningové testy protinádorových léčiv MeSH
• tretinoin aplikace a dávkování   MeSH
• vitaminy aplikace a dávkování   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• alfa receptor kyseliny retinové MeSH
• kalcifediol MeSH
• kalcitriol MeSH
• protinádorové látky MeSH
• receptory kalcitriolu MeSH
• tretinoin MeSH
• vitaminy MeSH

Although the administration of retinoids represents an important part of treatment for children suffering from high-risk neuroblastomas, approximately 50% of these patients do not respond to this therapy or develop resistance to retinoids during treatment. Our study focused on the comparative analysis of the expression of five genes and corresponding proteins (DDX39A, HMGA1, HMGA2, HOXC9 and PBX1) that have recently been discussed as possible predictive biomarkers of clinical response to retinoid differentiation therapy. Expression of these five candidate biomarkers was evaluated at both the mRNA and protein level in the same subset of 8 neuroblastoma cell lines after treatment with natural or synthetic retinoids. We found that the cell lines that were HMGA2-positive and/or HOXC9-negative have a reduced sensitivity to retinoids. Furthermore, the experiments revealed that the retinoid-sensitive cell lines showed a uniform pattern of change after treatment with both natural and sensitive retinoids: increased DDX39A and decreased PBX1 protein levels. Our results showed that in NBL cells, these putative protein biomarkers are associated with sensitivity or resistance to retinoids, and their endogenous or induced expression can distinguish between these two phenotypes.

• MeSH
• bexaroten farmakologie   MeSH
• biomarkery farmakologické metabolismus   MeSH
• chemorezistence účinky léků   genetika   MeSH
• DEAD-box RNA-helikasy genetika   metabolismus   MeSH
• dítě MeSH
• fenretinid farmakologie   MeSH
• fixace tkání MeSH
• homeodoménové proteiny genetika   metabolismus   MeSH
• isotretinoin farmakologie   MeSH
• kojenec MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• nádorové buněčné linie MeSH
• nádory nervového systému genetika   metabolismus   patologie   chirurgie   MeSH
• neuroblastom genetika   metabolismus   patologie   chirurgie   MeSH
• novorozenec MeSH
• pre-B-buněčný leukemický transkripční faktor 1 genetika   metabolismus   MeSH
• předškolní dítě MeSH
• proliferace buněk účinky léků   MeSH
• protein HMGA1A genetika   metabolismus   MeSH
• protein HMGA2 genetika   metabolismus   MeSH
• protinádorové látky farmakologie   MeSH
• tretinoin analogy a deriváty   farmakologie   MeSH
• zalévání tkání do parafínu MeSH
• Check Tag
• dítě MeSH
• kojenec MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• novorozenec MeSH
• předškolní dítě MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• 9,13-retinoic acid MeSH Prohlížeč
• bexaroten MeSH
• biomarkery farmakologické MeSH
• DDX39A protein, human MeSH Prohlížeč
• DEAD-box RNA-helikasy MeSH
• fenretinid MeSH
• HMGA2 protein, human MeSH Prohlížeč
• homeodoménové proteiny MeSH
• Hoxc9 protein, human MeSH Prohlížeč
• isotretinoin MeSH
• PBX1 protein, human MeSH Prohlížeč
• pre-B-buněčný leukemický transkripční faktor 1 MeSH
• protein HMGA1A MeSH
• protein HMGA2 MeSH
• protinádorové látky MeSH
• tretinoin MeSH

Retinoids represent a popular group of differentiation inducers that are successfully used in oncology for treatment of acute promyelocytic leukemia in adults and of neuroblastoma in children. The therapeutic potential of retinoids is based on their key role in the regulation of cell differentiation, growth, and apoptosis, which provides a basis for their use both in cancer therapy and chemoprevention. Nevertheless, patients treated with retinoids often exhibit or develop resistance to this therapy. Although resistance to retinoids is commonly categorized as either acquired or intrinsic, resistance as a single phenotypic feature is usually based on the same mechanisms that are closely related or combined in both of these types. In this review, we summarize the most common changes in retinoid metabolism and action that may affect the sensitivity of a tumor cell to treatment with retinoids. The availability of retinoids can be regulated by alterations in retinol metabolism or in retinoid intracellular transport, by degradation of retinoids or by their efflux from the cell. Retinoid effects on gene expression can be regulated via retinoid receptors or via other molecules in the transcriptional complex. Finally, the role of small-molecular-weight inhibitors of altered cell signaling pathways in overcoming the resistance to retinoids is also suggested.

• Klíčová slova
• cell differentiation, differentiation therapy, mechanisms of resistance, retinoids,
• MeSH
• biologický transport účinky léků   MeSH
• buněčná diferenciace účinky léků   MeSH
• chemorezistence účinky léků   MeSH
• genetická transkripce účinky léků   MeSH
• lidé MeSH
• receptory kyseliny retinové metabolismus   MeSH
• retinoidy metabolismus   farmakologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• receptory kyseliny retinové MeSH
• retinoidy MeSH

The induced differentiation of tumor cells into mature phenotypes is a promising strategy in cancer therapy. In this study, the effects of combined treatment with all-trans retinoic acid (ATRA) and lipoxygenase/cyclooxygenase inhibitors were examined in two osteosarcoma cell lines, Saos-2 and OSA-01. Caffeic acid and celecoxib were used as inhibitors of 5-lipoxygenase and of cyclooxygenase-2, respectively. Changes in the cell proliferation, matrix mineralization, and occurrence of differentiation markers were evaluated in treated cell populations at intervals. The results confirmed the capability of caffeic acid to enhance the antiproliferative effect of ATRA in both cell lines. In contrast, celecoxib showed the same effect in Saos-2 cells only. Furthermore, the extension of matrix mineralization was observed after combined treatment with ATRA and celecoxib or caffeic acid. The increased expression of osteogenic differentiation markers was observed in both cell lines after the combined application of ATRA and inhibitors. The obtained results clearly demonstrate the capability of lipoxygenase/cyclooxygenase inhibitors to enhance the antiproliferative and differentiating effect of ATRA in osteosarcoma cells, although some of these effects are specific and depend on the biological features of the respective tumor or cell line.

• MeSH
• buněčná diferenciace účinky léků   MeSH
• celekoxib MeSH
• inhibitory cyklooxygenasy farmakologie   MeSH
• inhibitory lipoxygenas farmakologie   MeSH
• kyseliny kávové farmakologie   MeSH
• lidé MeSH
• nádorové buněčné linie MeSH
• nádory kostí farmakoterapie   patologie   MeSH
• osteosarkom farmakoterapie   patologie   MeSH
• proliferace buněk účinky léků   MeSH
• protinádorové látky farmakologie   MeSH
• pyrazoly farmakologie   MeSH
• sulfonamidy farmakologie   MeSH
• tretinoin farmakologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• caffeic acid MeSH Prohlížeč
• celekoxib MeSH
• inhibitory cyklooxygenasy MeSH
• inhibitory lipoxygenas MeSH
• kyseliny kávové MeSH
• protinádorové látky MeSH
• pyrazoly MeSH
• sulfonamidy MeSH
• tretinoin MeSH

BACKGROUND: A detailed analysis of the expression of 440 cancer-related genes was performed after the combined treatment of medulloblastoma cells with all-trans retinoic acid (ATRA) and inhibitors of lipoxygenases (LOX) and cyclooxygenases (COX). The combinations of retinoids and celecoxib as a COX-2 inhibitor were reported to be effective in some regimens of metronomic therapy of relapsed solid tumors with poor prognosis. Our previous findings on neuroblastoma cells using expression profiling showed that LOX/COX inhibitors have the capability of enhancing the differentiating action of ATRA. Presented study focused on the continuation of our previous work to confirm the possibility of enhancing ATRA-induced cell differentiation in these cell lines via the application of LOX/COX inhibitors. This study provides more detailed information concerning the mechanisms of the enhancement of the ATRA-induced differentiation of medulloblastoma cells. METHODS: The Daoy and D283 Med medulloblastoma cell lines were chosen for this study. Caffeic acid (an inhibitor of 5-LOX) and celecoxib (an inhibitor on COX-2) were used in combined treatment with ATRA. The expression profiling was performed using Human Cancer Oligo GEArray membranes, and the most promising results were verified using RT-PCR. RESULTS: The expression profiling of the selected cancer-related genes clearly confirmed that the differentiating effects of ATRA should be enhanced via its combined administration with caffeic acid or celecoxib. This effect was detected in both cell lines. An increased expression of the genes that encoded the proteins participating in induced differentiation and cytoskeleton remodeling was detected in both cell lines in a concentration-dependent manner. This effect was also observed for the CDKN1A gene encoding the p21 protein, which is an important regulator of the cell cycle, and for the genes encoding proteins that are associated with proteasome activity. Furthermore, our results showed that D283 Med cells are significantly more sensitive to treatment with ATRA alone than Daoy cells. CONCLUSIONS: The obtained results on medulloblastoma cell lines are in accordance with our previous findings on neuroblastoma cells and confirm our hypothesis concerning the common mechanism of the enhancement of ATRA-induced cell differentiation in various types of pediatric solid tumors.

• Klíčová slova
• All-trans retinoic acid, Caffeic acid, Celecoxib, LOX and COX inhibitors, Medullobastoma,
• Publikační typ
• časopisecké články MeSH