Project description:Whole exome sequencing was performed on set of 48 DNA samples obtained from 16 EGFR mutated NSCLC patients whose tumors progressed following EGFR-TKI treatment. The DNA samples included baseline biopsy, rebiopsy and blood from the same patient. By comparing the variants in rebiopsy tumors and baseline tumors we aim to understand the genomic alterations responsible for the development of EGFR-TKI resistance in NSCLC patients.
Project description:Starting with H3122 cells, which harbor the EML4-ALK E13;A20 fusion and are known to be sensitive to ALK tyrosine kinase inhibitors, we generated isogenic pairs of ALK TKI sensitive and ALK TKI resistant cell lines using established methods (see Chmeliecki, J et al Science Trans Med 2011). We modeled resistance against the currently FDA approved ALK TKI, crizotinib (also called PF-1066). We also modeled resistance against a novel more potent ALK inhibitor, X-376 (ref: Lovly, CM et al Cancer Research 2011). We compared gene expression profiles between the 'parental' (ALK TKI sensitive) H3122 cells and the drug resistant cells (H3122 CR for Crizotinib resistant cells and H3122 XR for X-376 resistant cells).
Project description:In this report, we revealed that branched chain amino acid transaminase 1 (BCAT1) is highly enriched in both mouse and human TKI-resistant CML cells. Leukemia was almost completely abrogated upon BCAT1 knockdown during transplantation in a BCR-ABLT315I-induced murine TKI-resistant CML model . Moreover, knockdown of BCAT1 led to a dramatic decrease in the proliferation of TKI-resistant human leukemia cell lines. BCAA/BCAT1 signaling enhanced the phosphorylation of CREB, which is required for maintenance of TKI-resistant CML cells. Importantly, blockade of BCAA/BCAT1 signaling efficiently inhibited leukemogenesis both in vivo and in vitro.
Project description:Lung adenocarcinoma cells harboring epidermal growth factor receptor (EGFR) mutations are sensitive to EGFR tyrosine kinase inhibitors (TKIs). Prolonged cancer treatment will induce the development of acquired resistance to EGFR TKI. To gain insight into the molecular mechanisms of EGFR-TKIs resistance, we generate EGFR-TKI-resistant HCC827-8-1 cells to be analyzed by microarray with their parental HCC827cells.
Project description:Chronic myeloid leukaemia (CML) is a clonal haemopoietic stem cell (HSC) disorder associated with the BCR-ABL oncogene, which encodes a constitutively active tyrosine kinase. We have demonstrated the existence of CML HSC which are resistant to the tyrosine kinase inhibitors (TKI). We have hypothesised that CML stem cells are dependent on key survival pathways that are induced by TKI treatment. In order to elucidate these key survival pathways, we have investigated the transcriptional differences between CML stem/progenitor cells (CD34+38-) treated with TKIs (imatinib, dasatinib and nilotinib) at different time points (8 hours and 7 days, in the absence of growth factors) and by carrying out RNA profiling for the different populations. CD34+38- cells were isolated from chronic phase patient samples. >100ng of total RNA was amplified prior to analysis that was carried out with Affymetrix Human Gene 1.0 ST array.
Project description:In mammalian cells, gene copy number is tightly controlled to maintain gene expression and genome stability. However, a near-universal molecular feature across cancer types is oncogene amplification, which promotes cancer progression by dramatically increasing the copy number and expression of tumor-promoting genes. For example, in tyrosine kinase inhibitor (TKI)-resistant lung adenocarcinoma (LUAD), oncogene amplification occurs in over 40% of patients’ tumors. Despite the prevalence of oncogene amplification in TKI-resistant tumors, the mechanisms facilitating oncogene amplification are not fully understood. Here, we find that LUAD tumors exhibit a unique chromatin signature demarcated by strong CTCF and cohesin deposition in drug-naïve tumors, which correlates with the boundaries of oncogene amplicons in TKI-resistant LUAD cells. Throughout the acquisition of TKI resistance, we identified a global chromatin priming effect, marked by a dynamic increase of H3K27Ac, cohesin loading, and inter-TAD interactions, which occurs before the onset of oncogene amplification. Furthermore, we have identified that the protein METTL7A, which was previously reported to localize to the ER and inner nuclear membrane, has a novel chromatin regulatory function in binding to amplified oncogenes and regulating cohesin recruitment and inter-TAD interactions. Surprisingly, we discovered that METTL7A remodels the chromatin landscape prior to any noticeable oncogene copy number gains. Furthermore, while METTL7A depletion has little effect on drug-naïve cells, METTL7A depletion prevents the formation of TKI resistant-clones, highlighting the specific role of METTL7A as cells are acquiring resistance. In summary, we discovered an unexpected mechanism required for the acquisition of TKI resistance regulated by a largely uncharacterized factor, METTL7A. This discovery sheds new light into maintenance of oncogene copy number and paves the way to the development of new therapeutics for preventing TKI resistance in LUAD.