The present work aimed to identify reference genes for RT-qPCR studies of hypoxia in cervical cancer. From 422 candidate reference genes selected from the literature, we used Illumina array-based expression profiles to identify 182 genes not affected by hypoxia treatment in eight cervical cancer cell lines or correlated with the hypoxia-associated dynamic contrast-enhanced magnetic resonance imaging parameter ABrix in 42 patients. Among these genes, we selected nine candidates (CHCHD1, GNB2L1, IPO8, LASP1, RPL27A, RPS12, SOD1, SRSF9, TMBIM6) that were not associated with tumor volume, stage, lymph node involvement or disease progression in array data of 150 patients, for further testing by RT-qPCR. geNorm and NormFinder analyses of RT-qPCR data of 74 patients identified CHCHD1, SRSF9 and TMBIM6 as the most suitable set of reference genes, with stable expression both overall and across patient subgroups with different hypoxia status (ABrix) and clinical parameters. The suitability of the three candidates as reference genes were validated in studies of the hypoxia-induced genes DDIT3, ERO1A, and STC2. After normalizing with CHCHD1, SRSF9 and TMBIM6, the RT-qPCR data of these genes showed a significant correlation with Illumina expression (P<0.001, n=74) and ABrix (P<0.05, n=32), and the STC2 data were associated with clinical outcome, in accordance with the Illumina data. Thus, CHCHD1, SRSF9 and TMBIM6 seem to be suitable reference genes for studying hypoxia-related gene expression in cervical cancer samples by RT-qPCR. STC2 might be a useful prognostic hypoxia biomarker in cervical cancer that warrants further investigation.
Identification and Validation of Reference Genes for RT-qPCR Studies of Hypoxia in Squamous Cervical Cancer Patients.
Specimen part, Cell lineView Samples
Emerging biomarkers based on medical images and molecular characterization of tumor biopsies open up for combining the two disciplines and exploiting their synergy in treatment planning. We compared pretreatment classification of cervical cancer patients by two previously validated imaging- and gene-based hypoxia biomarkers, evaluated the influence of intratumor heterogeneity, and investigated the benefit of combining them in prediction of treatment failure. The imaging-based biomarker was hypoxic fraction, determined from diagnostic dynamic contrast enhanced (DCE)-MR images. The gene-based biomarker was a hypoxia gene expression signature determined from tumor biopsies. Paired data were available for 118 patients. Intratumor heterogeneity was assessed by variance analysis of MR images and multiple biopsies from the same tumor. The two biomarkers were combined using a dimension-reduction procedure. The biomarkers classified 75% of the tumors with the same hypoxia status. Both intratumor heterogeneity and distribution pattern of hypoxia from imaging were unrelated to inconsistent classification by the two biomarkers, and the hypoxia status of the slice covering the biopsy region was representative of the whole tumor. Hypoxia by genes was independent on tumor cell fraction and showed minor heterogeneity across multiple biopsies in 9 tumors. This suggested that the two biomarkers could contain complementary biological information. Combination of the biomarkers into a composite score led to improved prediction of treatment failure (HR:7.3) compared to imaging (HR:3.8) and genes (HR:3.0) and prognostic impact in multivariate analysis with clinical variables. In conclusion, combining imaging- and gene-based biomarkers enables more precise and informative assessment of hypoxia-related treatment resistance in cervical cancer, independent of intratumor heterogeneity.
Combining imaging- and gene-based hypoxia biomarkers in cervical cancer improves prediction of chemoradiotherapy failure independent of intratumour heterogeneity.
Specimen partView Samples
We have previously identified a prognostic 31-gene expression signature in locally advanced cervical cancer that is associated with tumor hypoxia and reflected by the dynamic contrast enhanced magnetic resonance (DCE-MR) image parameter ABrix. To bring the signature closer to clinical use, we here aimed to construct a classifier with key signature genes that retained an association to ABrix and separated the patients into groups with different hypoxia status and chemoradiotherapy outcome.
Integrative Analysis of DCE-MRI and Gene Expression Profiles in Construction of a Gene Classifier for Assessment of Hypoxia-Related Risk of Chemoradiotherapy Failure in Cervical Cancer.
Specimen part, Cell lineView Samples
We explored the prognostic impact of the dynamic contrast enhanced MR imaging (DCE-MRI) parameter ABrix in cervical cancer combined with global gene expression data to reveal the underlying molecular phenotype of the parameter and construct a gene signature that reflected ABrix. Based on 78 cervical cancer patients subjected to curative chemoradiotherapy, we identified a prognostic ABrix parameter by pharmacokinetic analysis of DCE-MR images based on the Brix model, where tumors with low ABrix appeared to be most aggressive. Gene set enrichment analysis of 46 tumors with pairwise DCE-MRI and gene expression data showed a significant correlation between ABrix and the hypoxia gene sets, whereas gene sets related to proliferation, radioresistance, and wound healing were not significant. Hypoxia gene sets specific for cervical cancer created in cell culture experiments, including targets of the hypoxia inducible factor (HIF1) and the unfolded protein response (UPR), were the most significant. In the remaining 32 tumors, low ABrix was associated with upregulation of HIF1 protein expression, as assessed by immunohistochemistry, consistent with increased hypoxia. Based on the hypoxia gene sets, a signature of 31 genes that were upregulated in tumors with low ABrix was constructed. This DCE-MRI hypoxia gene signature showed prognostic impact in an independent validation cohort of 109 patients.
Hypoxia-induced gene expression in chemoradioresistant cervical cancer revealed by dynamic contrast-enhanced MRI.
Specimen part, Cell line, TreatmentView Samples
Tumor hypoxia levels range from mild to severe and have different biological and therapeutical consequences, but are not easily assessable in patients. We present a method based on diagnostic dynamic contrast enhanced (DCE) magnetic resonance imaging (MRI) that visualizes a continuous range of hypoxia levels in tumors of cervical cancer patients. Hypoxia images were generated using an established approach based on pixel-wise combination of the DCE-MRI parameters e and Ktrans, reflecting oxygen consumption and supply, respectively. An algorithm to retrieve hypoxia levels from the images was developed and validated in 28 xenograft tumors, by comparing the MRI-defined levels with hypoxia levels derived from pimonidazole stained histological sections. We further established an indicator of hypoxia levels in patient tumors based on expression of nine hypoxia responsive genes. A strong correlation was found between these indicator values and the MRI-defined hypoxia levels in 63 patients. Chemoradiotherapy outcome of 74 patients was most strongly predicted by moderate hypoxia levels, whereas more severe or milder levels were less predictive. By combining gene expression profiles and MRI-defined hypoxia levels in cancer hallmark analysis, we identified a distribution of levels associated with each hallmark; oxidative phosphorylation and G2/M checkpoint were associated with moderate hypoxia, and epithelial-to-mesenchymal transition and inflammatory responses with significantly more severe levels. At the mildest levels, interferon response hallmarks, together with stabilization of HIF1A protein by immunohistochemistry, appearred significant. Thus, our method visualizes the distribution of hypoxia levels within patient tumors and has potential to distinguish levels of different prognostic and biological significance.
MRI Distinguishes Tumor Hypoxia Levels of Different Prognostic and Biological Significance in Cervical Cancer.
Cell line, TreatmentView Samples
We performed integrative gene dosage and expression profiling to identify candidate target genes of the prognostic 3p loss in cervical cancer.
Identification of eight candidate target genes of the recurrent 3p12-p14 loss in cervical cancer by integrative genomic profiling.
Specimen part, Cell lineView Samples
The aryl hydrocarbon receptor (AHR) functions in higher organisims in development, metabolism and toxic responses. Its Caenorhabditis elegans (C. elegans) ortholog, AHR-1, facilitates neuronal development, growth and movement. We investigated the effect of AHR mutation on the transcriptional profile of L4 stage C. elegans using RNA-seq and quantitative real-time PCR in order to understand better AHR-1 function at the genomic level. Illumina HiSeq 2000 sequencing yielded 51.1, 61.2 and 54.0 million reads from wild-type controls, ahr-1(ia03) and ahr-1(ju145) mutants, respectively, providing detection of over 18,000 transcripts in each sample. Fourteen transcripts were over-expressed and 125 under-expressed in both ahr-1 mutants when compared to wild-type. Under-expressed genes included soluble guanylate cyclase (gcy) family genes, some of which were previously demonstrated to be regulated by AHR-1. A neuropeptide-like protein gene, nlp-20, and an F-box domain protein gene fbxa-192 and its pseudogenes fbxa-191 and fbxa-193 were also under-expressed. Conserved xenobiotic response elements were identified in the 5'' flanking regions of some but not all of the gcy, nlp-20 and fbxa genes. These results extend previous studies demonstrating control of gcy family gene expression by AHR-1, and furthermore suggest a role of AHR-1 in regulation of a neuropeptide gene as well as pseudogenes. Overall design: One sample was created from each of the following strains: wild-type N2, ahr-1(ia03) mutant and ahr-1(ju145) mutant. In data analysis, each mutant sample was individually compared to the wild-type sample to find differentially expressed genes.
Transcriptional profiling reveals differential expression of a neuropeptide-like protein and pseudogenes in aryl hydrocarbon receptor-1 mutant Caenorhabditis elegans.
Negative-pressure wound therapy (NPWT) is widely used to improve skin wound healing and to accelerate wound bed preparation. Although NPWT has been extensively studied as a treatment for deep wounds, its effect on epithelialization of superficial dermal wounds remains unclear. To clarify the effect of NPWT on reepithelialization, we applied NPWT on split- thickness skin graft donor sites from the first postoperative day (POD) to the seventh POD. Six patients took part in the study and two samples were obtained from each. The first biopsy sample was taken at elective surgery before split-thickness skin grafting and the second one during reepithelialization on the seventh POD. In all 12 samples (eight from four NPWT patients, and four from two control patients) were collected for this study. From each sample, we carried out a comprehensive genome-wide microarray analysis. Data from patients receiving NPWT were compared groupwise with data from those not receiving NPWT.
Gene expression profiling of negative-pressure-treated skin graft donor site wounds.
Treatment, SubjectView Samples
Transgenic C. elegans strains that express human SUMO-1 under the control of pan-neuronal (aex-3) or pan muscular (myo-4) promoters were assayed for gene expression changes.
Overexpression of SUMO perturbs the growth and development of Caenorhabditis elegans.
Specimen partView Samples
In order to clarify the human response of re-epithelialization, we biopsied split-thickness skin graft donor site wounds immediately before and after harvesting, as well as during the healing process 3 and 7 days thereafter. Altogether 25 biopsies from 8 patients qualified for the study. All samples were analysed by genome-wide microarrays. Here we identified the genes associated with normal skin re-epithelialization on time-scale, and organized them by similarities according to their induction or suppression patterns during wound healing.
Human skin transcriptome during superficial cutaneous wound healing.
Specimen partView Samples