Discrimination and evaluation of lactoferrin and delta-lactoferrin gene expression levels in cancer cells and under inflammatory stimuli using TaqMan real-time PCR
Abstract:The lactoferrin gene is known to be expressed either constitutively or under inducible conditions such as hormonal stimuli or inflammation. Its transcription from alternative promoters leads to two products, lactoferrin (Lf) and delta-lactoferrin (DeltaLf) mRNAs the expressions of which are altered during oncogenesis. The comparison of the two enhancer/promoter regions revealed that the two isoforms might be differentially trans-activated. Nevertheless, concomitant expression of both transcripts has been found… Show more
“…Since this cancerous cell-line produces very low amounts of Lf isoform transcripts [4], [5], we established a stable and inducible MDA-MB-231 cell line expressing ΔLf under doxycycline induction. These cells were either induced by doxycycline to express ΔLf or treated with two different concentrations of hLf.…”
Section: Resultsmentioning
confidence: 99%
“…Isolated clones were expanded to obtain cells named MDA-MB-231 dox-. Expression of ΔLf was followed as described [5]. Clones used for the study did not produce any detectable ΔLf without induction.…”
Section: Methodsmentioning
confidence: 99%
“…Real-time PCR (qRT-PCR) were performed as described [5] using an Mx3005 thermal cycler system and Brilliant SYBER Green QPCR Master Mix (Stratagene, Agilent Technologies). DNA primer pairs and conditions used to amplify mRNA are compiled in Table S1.…”
Section: Methodsmentioning
confidence: 99%
“…The primer pairs were purchased from Eurogentec (Seraing, Belgium). TaqMan qRT-PCR was performed as described [5]. The ΔLf and Lf probes were 5′-FAM-labeled, the normalizing HPRT gene probe was 5′-VIC-labeled (Applied Biosystems, Life Technologies) and the 3′ non-fluorescent quencher (NFQ) (Applied Biosystems) was used for each probe.…”
Section: Methodsmentioning
confidence: 99%
“…The two main isoforms are secreted Lf (Lf) [1] and its nucleocytoplasmic counterpart, delta-lactoferrin (ΔLf) [2], [3]. Their expression is downregulated or silenced in cancer cells [2], [4], [5]. In some cancers, significantly lower levels of Lf and/or ΔLf correlated with more advanced disease and an unfavourable prognosis [4], [6].…”
BackgroundLactoferrins exhibit antitumoral activities either as a secretory lactoferrin or an intracellular delta-lactoferrin isoform. These activities involve processes such as regulation of the cell cycle and apoptosis. While lactoferrin has been shown to exert its function by activating different transduction pathways, delta-lactoferrin has been proven to act as a transcription factor. Like many tumor suppressors, these two proteins are under-expressed in several types of cancer, particularly in breast cancer.Methodology/Principal FindingsIn order to compare the differential effects of the re-introduction of lactoferrin isoforms in breast cancer cells we chose the cancerous mammary gland MDA-MB-231 cell line as a model. We produced a cell line stably expressing delta-lactoferrin. We also treated these cells with fresh purified human breast lactoferrin. We performed two quantitative proteomic studies in parallel using SILAC coupled to mass spectrometry in order to compare the effects of different doses of the two lactoferrin isoforms. The proteome of untreated, delta-lactoferrin expressing and human lactoferrin treated MDA-MB-231 cells were compared. Overall, around 5300 proteins were identified and quantified using the in-house developed MFPaQ software. Among these, expression was increased by 1.5-fold or more for around 300 proteins in delta-lactoferrin expressing cells and 190 proteins in lactoferrin treated cells. At the same time, about 200 and 40 proteins were found to be downregulated (0-0.7-fold) in response to delta-lactoferrin and lactoferrin, respectively.Conclusions/SignificanceRe-introduction of delta-lactoferrin and lactoferrin expression in MDA-MB-231 mainly leads to modifications of protein profiles involved in processes such as proliferation, apoptosis, oxidative stress, the ubiquitin pathway, translation and mRNA quality control. Moreover, this study identified new target genes of delta-lactoferrin transcriptional activity such as SelH, GTF2F2 and UBE2E1.
“…Since this cancerous cell-line produces very low amounts of Lf isoform transcripts [4], [5], we established a stable and inducible MDA-MB-231 cell line expressing ΔLf under doxycycline induction. These cells were either induced by doxycycline to express ΔLf or treated with two different concentrations of hLf.…”
Section: Resultsmentioning
confidence: 99%
“…Isolated clones were expanded to obtain cells named MDA-MB-231 dox-. Expression of ΔLf was followed as described [5]. Clones used for the study did not produce any detectable ΔLf without induction.…”
Section: Methodsmentioning
confidence: 99%
“…Real-time PCR (qRT-PCR) were performed as described [5] using an Mx3005 thermal cycler system and Brilliant SYBER Green QPCR Master Mix (Stratagene, Agilent Technologies). DNA primer pairs and conditions used to amplify mRNA are compiled in Table S1.…”
Section: Methodsmentioning
confidence: 99%
“…The primer pairs were purchased from Eurogentec (Seraing, Belgium). TaqMan qRT-PCR was performed as described [5]. The ΔLf and Lf probes were 5′-FAM-labeled, the normalizing HPRT gene probe was 5′-VIC-labeled (Applied Biosystems, Life Technologies) and the 3′ non-fluorescent quencher (NFQ) (Applied Biosystems) was used for each probe.…”
Section: Methodsmentioning
confidence: 99%
“…The two main isoforms are secreted Lf (Lf) [1] and its nucleocytoplasmic counterpart, delta-lactoferrin (ΔLf) [2], [3]. Their expression is downregulated or silenced in cancer cells [2], [4], [5]. In some cancers, significantly lower levels of Lf and/or ΔLf correlated with more advanced disease and an unfavourable prognosis [4], [6].…”
BackgroundLactoferrins exhibit antitumoral activities either as a secretory lactoferrin or an intracellular delta-lactoferrin isoform. These activities involve processes such as regulation of the cell cycle and apoptosis. While lactoferrin has been shown to exert its function by activating different transduction pathways, delta-lactoferrin has been proven to act as a transcription factor. Like many tumor suppressors, these two proteins are under-expressed in several types of cancer, particularly in breast cancer.Methodology/Principal FindingsIn order to compare the differential effects of the re-introduction of lactoferrin isoforms in breast cancer cells we chose the cancerous mammary gland MDA-MB-231 cell line as a model. We produced a cell line stably expressing delta-lactoferrin. We also treated these cells with fresh purified human breast lactoferrin. We performed two quantitative proteomic studies in parallel using SILAC coupled to mass spectrometry in order to compare the effects of different doses of the two lactoferrin isoforms. The proteome of untreated, delta-lactoferrin expressing and human lactoferrin treated MDA-MB-231 cells were compared. Overall, around 5300 proteins were identified and quantified using the in-house developed MFPaQ software. Among these, expression was increased by 1.5-fold or more for around 300 proteins in delta-lactoferrin expressing cells and 190 proteins in lactoferrin treated cells. At the same time, about 200 and 40 proteins were found to be downregulated (0-0.7-fold) in response to delta-lactoferrin and lactoferrin, respectively.Conclusions/SignificanceRe-introduction of delta-lactoferrin and lactoferrin expression in MDA-MB-231 mainly leads to modifications of protein profiles involved in processes such as proliferation, apoptosis, oxidative stress, the ubiquitin pathway, translation and mRNA quality control. Moreover, this study identified new target genes of delta-lactoferrin transcriptional activity such as SelH, GTF2F2 and UBE2E1.
Delta-lactoferrin (∆Lf) is a transcription factor belonging to the lactoferrin family, the expression of which inhibits cell proliferation and leads to Skp1 and DcpS gene transactivation. In this study, we showed that ∆Lf expression also induces cell death via apoptosis in HEK 293 and MCF7 cells using a cell viability assay and DNA fragmentation. Western blot analyses showed that apoptosis was caspase-9, 7 and 8 dependent. Proteolytic cleavage of the endonuclease PARP was significantly increased. The levels of expression of Bcl family members were detected by immunochemistry and showed that the Bcl-xl/Bax and Bcl-2/Bax protein ratios were decreased. We determined that the pro-apoptotic effects of ∆Lf are mainly mediated by the activation of the mitochondria-dependent death-signaling pathway. Apoptosis induction by ∆Lf is concomitant with increased cellular levels of Bax protein. Analysis of the Bax promoter region detected a ∆Lf response element located at -155 bp from the transcription start site. Both luciferase reporter gene and chromatin immunoprecipitation assays confirmed that ∆Lf interacts in vitro and in vivo specifically with this sequence. Its deletion, realized using directed mutagenesis, totally abolished ∆Lf transcriptional activity, identifying it as a ∆Lf-responsive element. These results indicate that the Bax gene is a novel ∆Lf target. Moreover we also showed that the O-GlcNAc/P interplay, which controls ∆Lf transcriptional activity, modulates Bax transactivation.
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