Project description:Chronic myeloid leukemia (CML) epitomizes successful targeted therapy, with 86% of patients in the chronic phase treated with tyrosine kinase inhibitors (TKIs) attaining remission. However, resistance to TKIs occurs during treatment, and patients with resistance to TKIs progress to the acute phase called Blast Crisis (BC), wherein the survival is restricted to 7-11 months. About 80 % of patients in BC are unresponsive to TKIs. This issue can be addressed by identifying a molecular signature which can predict resistance in CML-CP prior to treatment as well as by delineating the molecular mechanism underlying resistance. Herein, we report genomic analysis of CML patients and imatinib-resistant K562 cell line to achieve the same. WGS was performed on imatinib-sensitive and -resistant K562 cells. Library preparation was done by 30x WGS KAPA PCR-Free v2.1 kit, and Illumina HiSeq X sequencer was used for 2 x 150 bp paired-end sequencing. Our study identified accumulation of aberrations on chromosomes 1, 3, 7, 16 and 22 as predictive of occurrence of resistance. Further, recurrent amplification in chromosomal region 8q11.2-12.1 was detected in highly resistant K562 cells as well as CML patients. The genes present in this region were analyzed to understand molecular mechanism of imatinib resistance.
Project description:Drug resistance invariably limits the clinical efficacy of targeted therapy with kinase inhibitors against cancer. We found that targeted therapy with BRAF, ALK, or EGFR inhibitors induces a complex network of secreted signals in drug-stressed melanoma and lung adenocarcinoma cells. This therapy-induced secretome (TIS) stimulates the outgrowth, infiltration and metastasis of drug-resistant cancer clones in the tumour. Additionally, the TIS supports the survival of drug-sensitive cells, contributing to incomplete tumour regression. We used transcriptomic analysis of sensitive tumour cells and xenograft tumours treated with vehicle, vemurafenib, or crizotinib to identify the transcriptional drivers and to dissect the TIS in melanoma (A375, Colo800, UACC62) and lung adenocarcinoma (H3122). In addition, we utilize cell type–specific mRNA purification by translating ribosome affinity purification (TRAP) to identify pathways that are up-regulated in resistant cells (A375R) in response to the regressing tumour microenvironment.
Project description:The host range of African trypanosomes is influenced by innate protective molecules in the blood of primates. A subfraction of human high-density lipoprotein (HDL) containing apolipoprotein A-I, apolipoprotein L-I, and haptoglobin-related protein is toxic to Trypanosoma brucei brucei but not the human sleeping sickness parasite Trypanosoma brucei rhodesiense. It is thought that T. b. rhodesiense evolved from a T. b. brucei-like ancestor and expresses a defense protein that ablates the antitrypanosomal activity of human HDL. To directly investigate this possibility, we developed an in vitro selection to generate human HDL-resistant T. b. brucei. Here we show that conversion of T. b. brucei from human HDL sensitive to resistant correlates with changes in the expression of the variant surface glycoprotein (VSG) and abolished uptake of the cytotoxic human HDLs. Complete transcriptome analysis of the HDL-susceptible and -resistant trypanosomes confirmed that VSG switching had occurred but failed to reveal the expression of other genes specifically associated with human HDL resistance, including the serum resistance-associated gene (SRA) of T. b. rhodesiense. In addition, we found that while the original active expression site was still utilized, expression of three expression site-associated genes (ESAG) was altered in the HDL-resistant trypanosomes. These findings demonstrate that resistance to human HDLs can be acquired by T. b. brucei. Keywords: Trypanosoma, VSG, antigenic switching, HDL-resistance
Project description:Sub2, part of the mRNA QC system, was knocked down using RNAi. Total RNA was extracted and sequenced at BGI at three timepoints; zero, 24 and 48 hours post induction.
Project description:Reliable clinical tests for predicting cancer chemotherapy response are not available and individual markers failed to correctly predict resistance against anticancer agents. We hypothesized that gene expression patterns attributable to chemotherapy-resistant cells can be used as a classification tool for chemoresistance and provide novel candidate genes involved in anthracycline resistance mechanisms. We contrasted the expression profiles of 4 different human tumor cell lines of gastric, pancreatic, colon and breast origin and of their counterparts resistant to the topoisomerase inhibitors daunorubicin or doxorubicin. We also profiled the sensitive parental cells treated with doxorubicin for 24h. We interrogated Affymetrix HGU133A and U95A arrays independently. We applied two independent methods for data normalization and used Prediction Analysis of Microarrays (PAM) for feature selection. In addition, we established data sets related to drug resistance by using a “virtual array” composed of features represented on both types of oligonucleotide arrays. We identified 71 candidate genes associated with doxorubicine/daunorubicine resistance. To validate the microarray data, we also analyzed the expression of 12 selected genes by quantitative RT-PCR or immunocytochemistry, respectively. While the comparison of drug-sensitive versus drug-resistant cells yields candidates associated with drug resistance, the 24h treatment of sensitive parental cells produced a distinct transcriptional profile related to short-term drug effects. Keywords: cell type comparison See Summary. Note: this series includes Affymetrix HGU95A chips (difference between resistant and parental cell lines).
Project description:Human African trypanosomiasis, endemic to sub-Saharan Africa, is invariably fatal if untreated. Its causative agent is the protozoan parasite Trypanosoma brucei. Eflornithine is used as a first line treatment for human African trypanosomiasis, but there is a risk that resistance could thwart its use, even when used in combination therapy with nifurtimox. Eflornithine resistant trypanosomes were selected in vitro and subjected to biochemical and genetic analysis. The resistance phenotype was verified in vivo. Here we report the molecular basis of resistance. While the drug's target, ornithine decarboxylase, was unaltered in resistant cells and changes to levels of metabolites in the targeted polyamine pathway were not apparent, the accumulation of eflornithine was shown to be diminished in resistant lines. An amino acid transporter gene, TbAAT6 (Tb927.8.5450), was found to be deleted in two lines independently selected for resistance. Ablating expression of this gene in wildtype cells using RNA interference led to acquisition of resistance while expression of an ectopic copy of the gene introduced into the resistant deletion lines restored sensitivity, confirming the role of TbAAT6 in eflornithine action. Eflornithine resistance is easy to select through loss of a putative amino acid transporter, TbAAT6. The loss of this transporter will be easily identified in the field using a simple PCR test, enabling more appropriate chemotherapy to be administered.
Project description:African trypanosomes cause human African trypanosomiasis and animal African trypanosomiasis. They are transmitted by tsetse flies in sub-Saharan Africa. Although most famous for their mechanisms of immune evasion by antigenic variation, there have been recent important studies that illuminate important aspects of the biology of these parasites both in their mammalian host and during passage through their tsetse fly vector. This Primer overviews current research themes focused on these parasites and discusses how these biological insights and the development of new technologies to interrogate gene function are being used in the search for new approaches to control the parasite. The new insights into the biology of trypanosomes in their host and vector highlight that we are in a 'golden age' of discovery for these fascinating parasites.
Project description:Background: Non-coding RNAs have been proved to play an essential role in the development and progression of various cancers. However, the functions and mechanisms of non-coding RNA and mRNA in multi-drug resistance of colorectal cancer have not been fully elucidated.Methods: We performed RNA-sequencing to screen differentially expressed non-coding RNA and mRNA in CRC chemo-resistant and chemo-sensitive cell lines. Results: The results showed that 1779 mRNAs, 64 miRNAs, 11 circRNAs and 295 lncRNAs were common differentially expressed in two chemo-resistant cell lines.Conclusions:The results of the study may provide new theories and therapeutic targets for multi-drug resistance in colorectal cancer.
Project description:V600E being the most common mutation in BRAF, leads to constitutive activation of the MAPK signaling pathway. The majority of V600E BRAF positive melanoma patients treated with the BRAF inhibitor vemurafenib showed initial good clinical responses but relapsed due to acquired resistance to the drug. The aim of the present study was to identify possible biomarkers associated with the emergence of drug resistant melanoma cells. To this end we analyzed the differential gene expression of vemurafenib-sensitive and vemurafenib resistant brain and lung metastasizing melanoma cells. The major finding of this study is that the in vitro induction of vemurafenib resistance in melanoma cells is associated with an increased malignancy phenotype of these cells. Resistant cells expressed higher levels of genes coding for cancer stem cell markers (JARID1B, CD271 and Fibronectin) as well as genes involved in drug resistance (ABCG2), cell invasion and promotion of metastasis (MMP-1 and MMP-2). We also showed that drug-resistant melanoma cells adhere better to and transmigrate more efficiently through lung endothelial cells than drug-sensitive cells. The former cells also alter their microenvironment in a different manner from that of drug-sensitive cells. Biomarkers and molecular mechanisms associated with drug resistance may serve as targets for therapy of drug-resistant cancer.