Impact of Sustained Transforming Growth Factor-β Receptor Inhibition on Chromatin Accessibility and Gene Expression in Cultured Human Endometrial MSC

Endometrial mesenchymal stem cells (eMSC) drive the extraordinary regenerative capacity of the human endometrium. Clinical application of eMSC for therapeutic purposes is hampered by spontaneous differentiation and cellular senescence upon large-scale expansion in vitro. A83-01, a selective transforming growth factor-β receptor (TGFβ-R) inhibitor, promotes expansion of eMSC in culture by blocking differentiation and senescence, but the underlying mechanisms are incompletely understood. In this study, we combined RNA-seq and ATAC-seq to study the impact of sustained TGFβ-R inhibition on gene expression and chromatin architecture of eMSC. Treatment of primary eMSC with A83-01 for 5 weeks resulted in differential expression of 1,463 genes. Gene ontology analysis showed enrichment of genes implicated in cell growth whereas extracellular matrix genes and genes involved in cell fate commitment were downregulated. ATAC-seq analysis demonstrated that sustained TGFβ-R inhibition results in opening and closure of 3,555 and 2,412 chromatin loci, respectively. Motif analysis revealed marked enrichment of retinoic acid receptor (RAR) binding sites, which was paralleled by the induction of RARB, encoding retinoic acid receptor beta (RARβ). Selective RARβ inhibition attenuated proliferation and clonogenicity of A83-01 treated eMSC. Taken together, our study provides new insights into the gene networks and genome-wide chromatin changes that underpin maintenance of an undifferentiated phenotype of eMSC in prolonged culture.

Abstract A2: Cells of origin of the different subtypes of lung cancer

Lung cancer is the leading cause of cancer death worldwide. Five-year lung cancer survival is only 15% and lung cancer is responsible for more deaths than prostate, colon, pancreas, and breast cancers combined.

Understanding the cellular and molecular mechanism at the origin of lung cancer will generate great insights for better management of the disease. However, the lack of cell surface markers to identify and isolate early progenitor or stem cells in the normal lung represents a gap of knowledge that needs to be filled to identify cells of origin of lung cancers. By macroscopic isolation of different morphological region of the human lung and staining with cell surface markers, we have isolated distinct cell subpopulations by flow cytometry. Interestingly, these markers are expressed in some types of lung cancers but not others. We are characterizing the different subpopulations by immunostaining of cytospun cells and evaluating their in vitro colony formation capacity. In order to address potential cells of origin for the different lung tumor subtypes, gene signatures of the different normal epithelial subpopulations will be compared to the gene expression profiles of lung carcinomas available from public database.

These cell surface markers may be critical tools to identify stem/progenitor cells in the normal lung that could be the cell of origin of one type of lung cancer and not others.

Effect of thromboplastin and coagulometer interaction on the precision of the International Normalised Ratio

AIMS

To examine the magnitude of thromboplastin and coagulometer interactions on the precision of International Normalised Ratio (INR) values when the manufacturers' recommended instrument specific International Sensitivity Index (ISI) values are adopted for the INR calculation.

METHODS

The variability of INR values obtained from four automated phototopical coagulometers frequently used in North American laboratories was studied. When used with five commercial thromboplastins of moderate to high sensitivity (ISI values 0.92-1.97), 20 prothrombin time results were generated for each of a population of 98 patients on established warfarin treatment.

RESULTS

The mean INR values of the patients ranged from 2.05 to 2.81, depending on which reagent/coagulometer combination was used. Within patient variation increased as the median INR value increased. The mean coefficient of variation of within patient INR values was 10%; the mean coefficient of variation of the prothrombin time results in seconds and prothrombin time ratio were 21 and 18%, respectively.

CONCLUSIONS

There was considerable bias in the estimated ISI values of the thromboplastins compared with the manufacturers' instrument specific ISI value. Despite this apparent imperfection, our study clearly showed that the INR is preferable to other prothrombin time reporting formats for assessing the degree of anticoagulation for patients on warfarin treatment.