scholarly journals AR mRNA stability is increased with AR-antagonist resistance via 3′UTR variants

2020 ◽  
Vol 9 (1) ◽  
pp. 9-19 ◽  
Author(s):  
D A Dart ◽  
K Ashelford ◽  
W G Jiang
Keyword(s):  
Prostate Cancer ◽  
Cell Lines ◽  
Mrna Stability ◽  
Advanced Prostate Cancer ◽  
Actinomycin D ◽  
Acquired Resistance ◽  
Resistant Cell ◽  
Rna Seq ◽  
Serum Samples ◽  
Mrna Variant

Advanced prostate cancer is often treated with AR antagonists which target the androgen receptor (AR) on which the growth of the tumour depends. Prostate cancer often develops AR-antagonist resistance via a plethora of mechanisms, many of which are as yet unknown, but it is thought that AR upregulation or AR ligand-binding site mutations, may be responsible. Here we describe the production of cell lines based on LNCaP and VCaP, with acquired resistance to the clinically relevant AR antagonists, bicalutamide and enzalutamide. In these resistant cells, we observed, via RNA-seq, that new variants in the 3′UTR of the AR mRNA were detectable and that the levels were increased both with AR-antagonist treatment and with hormonal starvation. Around 20% of AR transcripts showed a 3 kb deletion within the 6.7 kb 3′UTR sequence. Actinomycin D and luciferase fusion studies indicated that this shorter mRNA variant was inherently more stable in anti-androgen-resistant cell lines. Of additional interest was that the AR UTR variant could be detected in the sera of prostate cancer patients in a cohort of serum samples collected from patients of Gleason grades 6–10, with an increasing level correlated to increasing grade. We hypothesise that the shorter AR UTR variant is a survival adaptation to low hormone levels and/or AR-antagonist treatment in these cells, where a more stable mRNA may allow higher levels of AR expression under these conditions.

scholarly journals Efficacy of the CDK4/6 Dual Inhibitor Abemaciclib in EGFR-Mutated NSCLC Cell Lines with Different Resistance Mechanisms to Osimertinib

Cancers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 6
Author(s):  
Silvia La Monica ◽  
Claudia Fumarola ◽  
Daniele Cretella ◽  
Mara Bonelli ◽  
Roberta Minari ◽  
...  
Keyword(s):  
Cell Lines ◽  
Kinase Inhibitor ◽  
Acquired Resistance ◽  
Growth Factor Receptor ◽  
Resistance Mechanisms ◽  
Resistant Cell ◽  
Nsclc Cell ◽  
Dual Inhibitor ◽  
Nsclc Patients ◽  
Egfr Mutated

Abemaciclib is an inhibitor of cyclin-dependent kinases (CDK) 4 and 6 that inhibits the transition from the G1 to the S phase of the cell cycle by blocking downstream CDK4/6-mediated phosphorylation of Rb. The effects of abemaciclib alone or combined with the third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) osimertinib were examined in a panel of PC9 and HCC827 osimertinib-resistant non-small cell lung cancer (NSCLC) cell lines carrying EGFR-dependent or -independent mechanisms of intrinsic or acquired resistance. Differently from sensitive cells, all the resistant cell lines analyzed maintained p-Rb, which may be considered as a biomarker of osimertinib resistance and a potential target for therapeutic intervention. In these models, abemaciclib inhibited cell growth, spheroid formation, colony formation, and induced senescence, and its efficacy was not enhanced in the presence of osimertinib. Interestingly, in osimertinib sensitive PC9, PC9T790M, and H1975 cells the combination of abemaciclib with osimertinib significantly inhibited the onset of resistance in long-term experiments. Our findings provide a preclinical support for using abemaciclib to treat resistance in EGFR mutated NSCLC patients progressed to osimertinib either as single treatment or combined with osimertinib, and suggest the combination of osimertinib with abemaciclib as a potential approach to prevent or delay osimertinib resistance in first-line treatment.

Genomic analysis of circulating tumor DNA in 3,334 patients with advanced prostate cancer to identify targetable BRCA alterations and AR resistance mechanisms.

2021 ◽  
Vol 39 (6_suppl) ◽  
pp. 25-25
Author(s):  
Hanna Tukachinsky ◽  
Russell Madison ◽  
Jon Chung ◽  
Lucas Dennis ◽  
Bernard Fendler ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Advanced Prostate Cancer ◽  
Acquired Resistance ◽  
Genomic Analysis ◽  
Circulating Tumor Dna ◽  
Resistance Mechanisms ◽  
Cancer Tissue ◽  
Castration Resistant Prostate Cancer ◽  
High Level ◽  
Tumor Dna

25 Background: Comprehensive genomic profiling (CGP) by next-generation sequencing (NGS) of circulating tumor DNA (ctDNA) from plasma provides a minimally invasive method to identify targetable genomic alterations (GAs) and resistance mechanisms in patients with metastatic castration-resistant prostate cancer (mCRPC). The circulating tumor fraction in patients with mCRPC and the clinical validity of GAs detected in plasma remain unknown. We evaluated the landscape of GAs using ctDNA-based CGP and assessed concordance with tissue-based CGP. Methods: Plasma from 3,334 patients with advanced prostate cancer (including 1,674 mCRPC screening samples from the TRITON2/3 trials and 1,660 samples from routine clinical CGP) was analyzed using hybrid-capture-based gene panel NGS assays. Results were compared with CGP of 2,006 metastatic prostate cancer tissue biopsies. Concordance was evaluated in 837 patients with both tissue (archival or contemporaneous) and plasma NGS results. Results: 3,127 patients [94%] had detectable ctDNA. BRCA1/2 were mutated in 295 patients [8.8%]. In concordance analysis, 72/837 [8.6%] patients had BRCA1/2 mutations detected in tissue, 67 [93%] of whom were also identified by ctDNA, and 20 patients were identified using ctDNA but not tissue [23% of all patients identified using ctDNA]. ctDNA detected subclonal BRCA1/2 reversions in 10 of 1,660 [0.6%] routine clinical CGP samples. AR alterations, including amplifications and hotspot mutations, which were detected in 940/2,213 patients [42%]. Rare AR compound mutations, rearrangements, and novel in-frame deletions were identified. Altered pathways included PI3K/AKT/mTOR [14%], WNT/β-catenin [17%], and RAS/RAF/MEK [5%]. Microsatellite instability was detected in 31/2,213 patients [1.4%]. Conclusions: In the largest study of mCRPC plasma samples conducted to date, CGP of ctDNA recapitulated the genomic landscape detected in tissue biopsies, with a high level of agreement in detection of BRCA1/2 alterations. It also identified patients who may have gained somatic BRCA1/2 alterations since archival tissue was collected. ctDNA detected more acquired resistance GAs than tissue, including novel AR-activating variants. The large percentage of patients with rich genomic signal from ctDNA, and the sensitive, specific detection of BRCA1/2 alterations position liquid biopsy as a compelling clinical complement to tissue CGP for patients with mCRPC.

scholarly journals Activation of the ERK Pathway Drives Acquired Resistance to Venetoclax in MM Cell Models

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 21-22
Author(s):  
Chandraditya Chakraborty ◽  
Yan Xu ◽  
Yao Yao ◽  
Eugenio Morelli ◽  
Anil Aktas-Samur ◽  
...  
Keyword(s):  
Board Of Directors ◽  
Cell Lines ◽  
Acquired Resistance ◽  
Gene Set Enrichment Analysis ◽  
Erk Pathway ◽  
Rna Seq ◽  
Intrinsic Resistance ◽  
Private Company ◽  
Advisory Committees ◽  
High Doses

Multiple myeloma (MM) is a hematological malignancy characterized by various genetic abnormalities including translocations involving the IgH gene at 14q32. Amongst these, t(11;14) is one of the most common translocations. Recent clinical data suggests a significant impact of Venetoclax, a small molecule inhibitor of BCL2, in this subgroup of MM patients, representing the first example of personalized medicine in MM and opening a wide range of research aiming at elucidating its mechanism of action. However, despite the initial positive response to the drug, a significant proportion of patients eventually develop resistance and relapse. To delineate the mechanisms that contribute to the development of an acquired drug-tolerant/resistance phenotype, we modeled the response to Venetoclax in 2 MM cell lines (KMS27 and KMS-12PE with IC50 of 35.47nM and 3.64nM, respectively). Whereas the vast majority of cells plated into 96-well plates were killed within a few days of exposure to a high dose of drug concentration, we detected a small fraction of viable, largely quiescent cells, which were expanded by culturing them in high doses of Venetoclax. We successfully generated 4 independent clones from each cell line, that were single cell-cloned with continued growth in the presence of high doses of Venetoclax. These clones labelled as drug-tolerant expanded persisters (DTEP) were investigated for the mechanisms driving drug tolerance and resistance against Venetoclax. First, we observed that altered expression of apoptotic regulators were associated with Venetoclax resistance in DTEP cells. We indeed observe a significant increase in the anti-apoptotic proteins MCL1 and BCL-XL in DTEP clones, which translated in our observation of improved sensitivity to MCL1 and BCL-xL inhibitors (S63845 and A-1155463 respectively). We performed both whole genome sequencing (WGS) and RNA-seq to evaluate if DTEP cells undergo transcriptional adaptation via genomic or epigenomic regulation and transcriptional reprograming during development of acquired drug resistance. While, WGS analysis didn't show any significant differences between parental and resistant clones, transcriptomic analysis showed both shared and unique transcriptome signatures in the DTEP clones. Gene set enrichment analysis (GSEA) of the common significantly modulated genes in the resistant clones revealed that the genes belonging to the PKA-ERK-CREB pathway were significantly upregulated in resistant clones, while apoptotic genes were downregulated compared to parental cells. Western blot analysis confirmed activation of ERK and the downstream target cAMP response element-binding (CREB) gene in resistant clones; and importantly treatment with the ERK inhibitor U0126 rescued the resistance to Venetoclax, providing a synergistic activity in resistant clones but not in parental cells, with decreased cell viability and increased apoptotic cell death. To evaluate if the ERK pathway was also associated with intrinsic resistance to Venetoclax, we assessed a panel of 24 MM cell lines and then calculated Pearson correlation coefficients between the measured drug activity and individual gene expression levels (by RNA-seq) across all cell lines and subjected the resulting rank-ordered gene list to GSEA. This analysis showed that mechanisms driving the DTEP phenotype are different from those associated with the intrinsic resistance to Venetoclax. RNA processing and splicing pathways were strongly enriched, with high expression of these genes correlating with increased sensitivity. Moreover, among the genes correlated with a resistant phenotype, we observed that the gene G0S2 was significantly downregulated in the resistant cell lines. G0S2 is a tumor suppressor gene that binds and inhibits BCL2. Interestingly, we observed that while G0S2 is downregulated in MM compared to normal plasma cells, t(11:14) patients have a higher expression. We are now in the process of validating G0S2 in MM and its contribution to Venetoclax sensitivity in MM. In conclusion, we here provide evidences of molecular mechanisms of acquired resistance to Venetoclax with activation of the ERK pathway as one of the prime targets. Combining Venetoclax with ERK inhibitor may therefore prevent or overcome the acquired resistance to Venetoclax observed in MM patients. Disclosures Fulciniti: NIH: Research Funding. Munshi:C4: Current equity holder in private company; OncoPep: Consultancy, Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties; BMS: Consultancy; Adaptive: Consultancy; Legend: Consultancy; Amgen: Consultancy; AbbVie: Consultancy; Karyopharm: Consultancy; Takeda: Consultancy; Janssen: Consultancy. Anderson:Oncopep and C4 Therapeutics.: Other: Scientific Founder of Oncopep and C4 Therapeutics.; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Sanofi-Aventis: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Millenium-Takeda: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees.

scholarly journals Dissecting Mechanisms of Melanoma Resistance to BRAF and MEK Inhibitors Revealed Genetic and Non-Genetic Patient- and Drug-Specific Alterations and Remarkable Phenotypic Plasticity

Cells ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 142 ◽  
Author(s):  
Mariusz L. Hartman ◽  
Malgorzata Sztiller-Sikorska ◽  
Anna Gajos-Michniewicz ◽  
Malgorzata Czyz
Keyword(s):  
Phenotypic Plasticity ◽  
Cell Lines ◽  
Mapk Pathway ◽  
Acquired Resistance ◽  
Resistance Mechanisms ◽  
Genetic Alterations ◽  
Resistant Cell ◽  
Cross Resistance ◽  
Preclinical Model ◽  
Development Of Resistance

The clinical benefit of MAPK pathway inhibition in BRAF-mutant melanoma patients is limited by the development of acquired resistance. Using drug-naïve cell lines derived from tumor specimens, we established a preclinical model of melanoma resistance to vemurafenib or trametinib to provide insight into resistance mechanisms. Dissecting the mechanisms accompanying the development of resistance, we have shown that (i) most of genetic and non-genetic alterations are triggered in a cell line- and/or drug-specific manner; (ii) several changes previously assigned to the development of resistance are induced as the immediate response to the extent measurable at the bulk levels; (iii) reprogramming observed in cross-resistance experiments and growth factor-dependence restricted by the drug presence indicate that phenotypic plasticity of melanoma cells largely contributes to the sustained resistance. Whole-exome sequencing revealed novel genetic alterations, including a frameshift variant of RBMX found exclusively in phospho-AKThigh resistant cell lines. There was no similar pattern of phenotypic alterations among eleven resistant cell lines, including expression/activity of crucial regulators, such as MITF, AXL, SOX, and NGFR, which suggests that patient-to-patient variability is richer and more nuanced than previously described. This diversity should be considered during the development of new strategies to circumvent the acquired resistance to targeted therapies.

scholarly journals Resistance to SL-401 in AML and BPDCN Is Associated with Loss of the Diphthamide Synthesis Pathway Enzyme DPH1 and Is Reversible By Azacitidine

Blood ◽  
2017 ◽  
Vol 130 (Suppl_1) ◽  
pp. 797-797 ◽  
Author(s):  
Jason Stephansky ◽  
Katsuhiro Togami ◽  
Mahmoud Ghandi ◽  
Joan Montero ◽  
Nick vonEgypt ◽  
...  
Keyword(s):  
Cell Lines ◽  
De Novo ◽  
Phase 1 ◽  
Acquired Resistance ◽  
Survival Advantage ◽  
Target Cells ◽  
Rna Seq ◽  
Adp Ribosylation ◽  
Synergistic Cytotoxicity ◽  
Resistant Cells

Abstract SL-401 is a novel targeted therapy comprised of recombinant interleukin 3 (IL3) fused to a truncated diphtheria toxin (DT) payload. SL-401 delivers DT to cells expressing the IL3 receptor (CD123). After internalization, DT catalyzes ADP ribosylation of eukaryotic elongation factor 2 (eEF2), blocking protein synthesis and killing target cells. SL-401 is currently in clinical trials for CD123+ cancers, including acute myeloid leukemia (AML) and blastic plasmacytoid dendritic cell neoplasm (BPDCN). Other than CD123 expression, the determinants of response are largely unknown. Our goal was to study mechanisms of de novo and acquired resistance to inform combination strategies and enhance the efficacy of SL-401. In 16 AML and BPDCN patients enrolled in a phase 1-2 trial, we did not see decreased expression of CD123 by flow cytometry during or after SL-401. To study alternative resistance mechanisms, we generated 3-6 independent SL-401 resistant clones from each of 4 CD123+ AML (THP1, NOMO1, EOL1) or BPDCN (CAL1) cell lines. We treated cells with the LD95 (lethal dose to 95%), retreating upon recovery. All lines developed >2-3 log resistance to SL-401 within 28 days. All resistant clones maintained CD123 surface expression, consistent with what we observed in patients. Using confocal microscopy, we saw that a fluorescently tagged SL-401 was internalized equally in resistant and parental cells. SL-401 resistant cells were also resistant to full length DT, suggesting that the mechanism of resistance involved DT rather than IL3 binding/internalization. We performed whole transcriptome RNA-sequencing and whole exome sequencing (WES) on parental and SL-401 resistant cells. There were no recurrent acquired DNA mutations. However, in RNA-seq the most downregulated gene in 6 independent clones from 2 lines was DPH1 (FC -7.5, FDR<0.0001). DPH1 is the first enzyme in a cascade that converts histidine 715 on eEF2 to diphthamide, the direct target for ADP ribosylation by DT. Decreased expression of DPH1 was confirmed in the 6 resistant clones by qRT-PCR, and in 3 clones from an additional line. Across 33 cell lines and subclones there was an inverse linear correlation between DPH1 level and SL-401 IC50 (P=0.0005). To validate this finding in patients, we performed paired RNA-seq on CD45+CD123+ sorted blasts from 2 AMLs pre & post 2 cycles of SL-401. Both patients' AMLs had reduced DPH1 after exposure to SL-401 (mean -2.1 fold). To determine if loss of DPH1 was sufficient to confer de novo resistance to SL-401, we generated THP1, NOMO1, and CAL1 cells stably expressing the Cas9 nuclease and transduced them with 1 of 4 DPH1-targeting or 2 non-targeting CRISPR sgRNAs co-expressing GFP. Four days after infection at titers that achieve ~20% GFP+ cells, we treated with the LD95 of SL-401. We observed a survival advantage for DPH1 sgRNA-transduced cells (2.9 fold increase in GFP+ cells, P<0.0001) and decreased apoptosis measured by AnnexinV positivity, compared to GFP- cells in the same cultures. By contrast, there was no survival advantage for cells transduced with control sgRNAs. These data suggest that DPH1 loss is sufficient to mediate SL-401 resistance in AML and BPDCN. Pseudomonas toxin (PT) also targets eEF2 on diphthamide, and PT resistance in a B-ALL cell line has been associated with DPH1 loss via reversible promoter CpG DNA methylation (Hu, Leuk Res 2013). Therefore, we tested the DNA methyltransferase inhibitor azacitidine in combination with SL-401 and observed synergistic cytotoxicity, in naïve (combination index (CI) = 0.45; <1 indicates synergy) and SL-401 resistant (CI = 0.55) cells. Most strikingly, 4-week pulsatile treatment with non-lethal "epigenetic" doses of azacitidine (300 nM 2d on/2d off) fully reversed SL-401 resistance in 6 CAL1 and THP1 clones that were insensitive at baseline (Figure). Controls grown in vehicle or with weekly SL-401 challenge showed no reversion, suggesting that azacitidine had a specific sensitizing effect. Restoration of SL-401 sensitivity was accompanied by an increase in DPH1 expression compared to resistant clones. In summary, we found that DPH1 is a biomarker of SL-401 activity and acquired resistance, and resistance is reversible by azacitidine. Based on these data, we have initiated a multicenter phase 1 trial of the combination of SL-401 and azacitidine in patients with AML or MDS (NCT03113643), with correlative laboratory studies designed to explore these hypotheses. Disclosures vonEgypt: Stemline Therapeutics: Employment. Lindsay: Stemline Therapeutics: Employment. Brooks: Stemline Therapeutics: Employment, Equity Ownership, Patents & Royalties. Lane: Stemline Therapeutics: Research Funding; N-of-one: Consultancy.

scholarly journals Identifying Mechanisms Associated with Venetoclax Resistance in Multiple Myeloma (MM)

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 2668-2668
Author(s):  
Yuan Xiao Zhu ◽  
Laura Ann Bruins ◽  
Joseph Ahmann ◽  
Cecilia Bonolo De Campos ◽  
Esteban Braggio ◽  
...  
Keyword(s):  
Cell Line ◽  
Board Of Directors ◽  
Cell Lines ◽  
Acquired Resistance ◽  
Resistant Cell ◽  
Resistant Cell Line ◽  
Sensitive Cell ◽  
Advisory Committees ◽  
Bcl2 Family ◽  
Family Regulation

Abstract Venetoclax (VTX) is a selective small-molecule inhibitor of BCL-2 that exhibits antitumoral activity against MM cells presenting lymphoid features and those with translocation t(11;14). Despite its impressive clinical activity, VTX therapy for a prolonged duration can lead to drug resistance. Therefore, it is important to understand the underlying mechanisms of resistance in order to develop strategies to prevent or overcome resistance. In the present study, we established four VTX resistant human myeloma cell lines (HMCLs) from four sensitive HMCLs, including three with t(11;14), in culture with a stepwise increase in treatment dose with VTX. To identify the molecular basis of acquired VTX resistance, whole exon sequencing (WES), mRNA-sequencing (mRNAseq), and protein expression assays were performed in the four isogenic VTX-sensitive/resistant HMCLs and three MM patients with samples collected before VTX administration and after clinical resistance to the drug. Compared with sensitive cell lines and patient samples collected before VTX administration, mRNAseq analysis identified downregulation of BIM and upregulation of BCLXL in both resistant cell lines and MM cells from relapse patients. Other transcriptional changes detected included upregulation of AURKA, BIRC3, BIRC5, and IL32. Enrichment analysis of differentially expressed genes suggested involvement of PI3K and MAPK signaling, likely associated with cytokines, growth factors (EGF, FGF and IGF family members), and receptor tyrosine kinase (EGF and FGF). Western blot analysis was performed to compare BCL2 family expression in resistant cell lines versus sensitive cell lines and it showed upregulation of BCL2 survival members (such as MCL-1 and BCLXL), and downregulation of pro-apoptotic BH3 members (such as BIM and PUMA). BIM expression was completely lost in one resistant cell line, and introduction of exogenous BIM into this cell line enhanced VTX sensitivity. Interestingly, BCL2 was upregulated in some resistant cell lines generated after a long-term treatment with VTX, suggesting BCL2 expression level may not be suitable as a marker of VTX sensitivity for acquired resistance. Unlike in CLL, BCL2 mutations were not identified through WES in any resistant cell lines or primary patient sample harvested after relapse. While 8 genes were mutated in two resistant samples , no clear mutational pattern emerged . Based on the above, we further tested some specific inhibitors in in vitro or ex vivo cell models to help understanding resistant mechanism and identify strategies to overcome VTX resistance. We found that inhibition of MCL-1, with the compound S68345, substantially enhanced VTX sensitivity in three resistant HMCLs and in primary cells from one relapsed MM patient. A BCLXL inhibitor (A155463) only significantly enhanced VTX sensitivity in one resistant cell line after co-treatment with VTX. Co-treatment of the other three resistant cell lines with VTX, S68345 and A155463 resulted in the most synergistic anti-myeloma activity, suggesting those cell lines are co-dependent on MCL-1, BCLXL, and BCL2 for survival, although they are more dependent on MCL-1. We also found that inhibition of PI3K signaling, IGF1, RTK (EGF and FGF) and AURKA significantly increased VTX sensitivity, partially through downregulation of MCL-1, and BCLXL, and upregulation of BIM. Conventional anti-MM drugs such as dexamethasone, bortezomib and lenalidomide, were shown to have little activity on augmenting VTX sensitivity in most resistant cell lines. In summary, we find that acquired resistance to VTX in MM is largely associated with BCL2 family regulation, including upregulation of survival members such as MCL-1, BCLXL, BCL2, and downregulation of pro-apoptotic members, especially BIM. Our study also indicates that upstream signaling involved in BCL2 family regulation during acquired resistance is likely related to cytokine, growth factor, and/or RTK-induced cell signaling such as PI3K. Co-inhibition of MCL-1, or BCLXL, as well as the upstream PI3K, RTK (FGF and EGF), IGF-1 mediated signaling were effective in overcoming VTX resistance. Disclosures Fonseca: Mayo Clinic in Arizona: Current Employment; Amgen: Consultancy; BMS: Consultancy; Celgene: Consultancy; Takeda: Consultancy; Bayer: Consultancy; Janssen: Consultancy; Novartis: Consultancy; Pharmacyclics: Consultancy; Sanofi: Consultancy; Merck: Consultancy; Juno: Consultancy; Kite: Consultancy; Aduro: Consultancy; OncoTracker: Consultancy, Membership on an entity's Board of Directors or advisory committees; GSK: Consultancy; AbbVie: Consultancy; Patent: Prognosticaton of myeloma via FISH: Patents & Royalties; Scientific Advisory Board: Adaptive Biotechnologies: Membership on an entity's Board of Directors or advisory committees; Caris Life Sciences: Membership on an entity's Board of Directors or advisory committees.

scholarly journals Rho-mediated gene transcription promotes BRAF inhibitor resistance in de-differentiated melanoma cells

2018 ◽  
Author(s):  
SA Misek ◽  
KM Appleton ◽  
TS Dexheimer ◽  
EM Lisabeth ◽  
RS Lo ◽  
...  
Keyword(s):  
Cell Lines ◽  
Gene Transcription ◽  
Melanoma Cell ◽  
Cutaneous Melanoma ◽  
Acquired Resistance ◽  
Rho Kinase ◽  
Braf Inhibitor ◽  
Resistant Cell ◽  
Melanoma Cell Lines

AbstractOver half of cutaneous melanoma tumors have BRAFV600E/Kmutations. Acquired resistance to BRAF inhibitors (BRAFi) remains a major hurdle in attaining durable therapeutic responses. In this study we demonstrate that approximately 50-60% of melanoma cell lines with vemurafenib resistance acquiredin vitroshow activation of RhoA family GTPases. In BRAFi-resistant melanoma cell lines and tumors, activation of RhoA is correlated with decreased expression of melanocyte lineage genes. Using a machine learning approach, we built gene expression-based models to predict drug sensitivity for 265 common anti-cancer compounds. We then projected these signatures onto the collection of TCGA cutaneous melanoma and found that poorly differentiated tumors were predicted to have increased sensitivity to multiple Rho kinase (ROCK) inhibitors. Two transcriptional effectors downstream of Rho, MRTF and YAP1, are activated in the RhoHighBRAFi-resistant cell lines, and resistant cells are more sensitive to inhibition of these transcriptional mechanisms. Taken together, these results support the concept of targeting Rho-regulated gene transcription pathways as a promising therapy approach to restore sensitivity to BRAFi-resistant tumors or as a combination therapy to prevent the onset of drug resistance.

scholarly journals TUBB3 Reverses Resistance to Docetaxel and Cabazitaxel in Prostate Cancer

2019 ◽  
Vol 20 (16) ◽  
pp. 3936 ◽  
Author(s):  
Yohei Sekino ◽  
Xiangrui Han ◽  
Takafumi Kawaguchi ◽  
Takashi Babasaki ◽  
Keisuke Goto ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Cell Lines ◽  
Resistant Cell ◽  
Pi3k Inhibitor ◽  
Pten Expression ◽  
Cross Resistance ◽  
Pi3k Inhibitor Ly294002 ◽  
Resistant Cells

Recent studies have reported that TUBB3 overexpression is involved in docetaxel (DTX) resistance in prostate cancer (PCa). The aim of this study was to clarify the role of TUBB3 in DTX and cabazitaxel (CBZ) resistance, and cross-resistance between DTX and CBZ in PCa. We analyzed the effect of TUBB3 knockdown on DTX and CBZ resistance and examined the interaction between TUBB3 and PTEN. We also investigated the role of phosphoinositide 3-kinases (PI3K) inhibitor (LY294002) in DTX and CBZ resistance. TUBB3 expression was upregulated in DTX-resistant and CBZ-resistant cells. TUBB3 knockdown re-sensitized DTX-resistant cells to DTX and CBZ-resistant cells to CBZ. Additionally, TUBB3 knockdown re-sensitized DTX-resistant cell lines to CBZ, indicating that TUBB3 mediates cross-resistance between DTX and CBZ. Knockdown of TUBB3 enhanced PTEN expression, and PTEN knockout enhanced TUBB3 expression. LY294002 suppressed TUBB3 expression in DTX-resistant and CBZ-resistant cell lines. LY294002 re-sensitized DTX-resistant cell lines to DTX and CBZ-resistant cell lines to CBZ. These results suggest that TUBB3 is involved in DTX resistance and CBZ resistance. A combination of LY294002/DTX and that of LY294002/CBZ could be potential strategies for PCa treatment.

scholarly journals Efficacy of the CDK7 Inhibitor on EMT-Associated Resistance to 3rd Generation EGFR-TKIs in Non-Small Cell Lung Cancer Cell Lines

Cells ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 2596
Author(s):  
Wonjun Ji ◽  
Yun Jung Choi ◽  
Myoung-Hee Kang ◽  
Ki Jung Sung ◽  
Dong Ha Kim ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Small Cell Lung Cancer ◽  
Cell Lines ◽  
Cell Lung Cancer ◽  
Acquired Resistance ◽  
Resistant Cell ◽  
Small Cell ◽  
Small Cell Lung ◽  
Egfr Tki ◽  
Egfr Tkis

Epithelial to mesenchymal transition (EMT) is associated with resistance during EGFR tyrosine kinase inhibitor (EGFR-TKI) therapy. Here, we investigated whether EMT is associated with acquired resistance to 3rd generation EGFR-TKIs, and we explored the effects of cyclin-dependent kinase 7 (CDK7) inhibitors on EMT-mediated EGFR-TKIs resistance in non-small cell lung cancer (NSCLC). We established 3rd generation EGFR-TKI resistant cell lines (H1975/WR and H1975/OR) via repeated exposure to WZ4002 and osimertinib. The two resistant cell lines showed phenotypic changes to a spindle-cell shape, had a reduction of epithelial marker proteins, an induction of vimentin expression, and enhanced cellular mobility. The EMT-related resistant cells had higher sensitivity to THZ1 than the parental cells, although THZ1 treatment did not inhibit EGFR activity. This phenomenon was also observed in TGF-β1 induced EMT cell lines. THZ1 treatment induced G2/M cell cycle arrest and apoptosis in all of the cell lines. In addition, THZ1 treatment led to drug-tolerant, EMT-related resistant cells, and these THZ1-tolerant cells partially recovered their sensitivity to 3rd generation EGFR-TKIs. Taken together, EMT was associated with acquired resistance to 3rd generation EGFR-TKIs, and CDK7 inhibitors could potentially be used as a therapeutic strategy to overcome EMT associated EGFR-TKI resistance in NSCLC.

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