scholarly journals SATB2 induction of a neural crest mesenchyme-like program drives invasion and drug resistance in melanoma

2020 ◽  
Author(s):  
Maurizio Fazio ◽  
Ellen van Rooijen ◽  
Michelle Dang ◽  
Glenn van de Hoek ◽  
Julien Ablain ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Neural Crest ◽  
Transcriptional Regulators ◽  
Human Melanoma ◽  
Drug Resistant ◽  
Transcriptional Program ◽  
Transcriptional Rewiring ◽  
Transcriptional Adaptation ◽  
Invadopodia Formation

Recent genomic and scRNA-seq analyses of melanoma identified common transcriptional states correlating with invasion or drug resistance, but failed to find recurrent drivers of metastasis. To test whether transcriptional adaptation can drive melanoma progression, we made use of a zebrafish mitfa:BRAFV600E;tp53-/- model, in which malignant progression is characterized by minimal genetic evolution. We undertook an overexpression-screen of 80 epigenetic/transcriptional regulators and found neural crest-mesenchyme developmental regulator SATB2 to accelerate aggressive melanoma development. Its overexpression induces invadopodia formation and invasion in zebrafish tumors and human melanoma cell lines. SATB2 binds and activates neural crest-regulators, including pdgfab and snai2. The transcriptional program induced by SATB2 overlaps with known MITFlowAXLhlgh and AQP1+NGFR1high drug resistant states and functionally drives enhanced tumor propagation and resistance to Vemurafenib in vivo. Here we show that melanoma transcriptional rewiring by SATB2 to a neural crest mesenchyme-like program can drive invasion and drug resistance in endogenous tumors.

scholarly journals SATB2 induction of a neural crest mesenchyme-like program drives melanoma invasion and drug resistance

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Maurizio Fazio ◽  
Ellen van Rooijen ◽  
Michelle Dang ◽  
Glenn van de Hoek ◽  
Julien Ablain ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Neural Crest ◽  
Transcriptional Regulators ◽  
Human Melanoma ◽  
Drug Resistant ◽  
Transcriptional Program ◽  
Transcriptional Rewiring ◽  
Transcriptional Adaptation ◽  
Invadopodia Formation

Recent genomic and scRNA-seq analyses of melanoma demonstrated a lack of recurrent genetic drivers of metastasis, while identifying common transcriptional states correlating with invasion or drug resistance. To test whether transcriptional adaptation can drive melanoma progression, we made use of a zebrafish mitfa:BRAFV600E;tp53-/- model, in which malignant progression is characterized by minimal genetic evolution. We undertook an overexpression-screen of 80 epigenetic/transcriptional regulators and found neural crest-mesenchyme developmental regulator SATB2 to accelerate aggressive melanoma development. Its overexpression induces invadopodia formation and invasion in zebrafish tumors and human melanoma cell lines. SATB2 binds and activates neural crest-regulators, including pdgfab and snai2. The transcriptional program induced by SATB2 overlaps with known MITFlowAXLhigh and AQP1+NGFR1high drug-resistant states and functionally drives enhanced tumor propagation and resistance to Vemurafenib in vivo. In summary, we show that melanoma transcriptional rewiring by SATB2 to a neural crest mesenchyme-like program can drive invasion and drug resistance in autochthonous tumors.

scholarly journals How Neural Crest Transcription Factors Contribute to Melanoma Heterogeneity, Cellular Plasticity, and Treatment Resistance

2021 ◽  
Vol 22 (11) ◽  
pp. 5761
Author(s):  
Anja Wessely ◽  
Theresa Steeb ◽  
Carola Berking ◽  
Markus Vincent Heppt
Keyword(s):  
Drug Resistance ◽  
Neural Crest ◽  
Physiological Function ◽  
Acquired Resistance ◽  
Treatment Resistance ◽  
Transcriptional Regulators ◽  
Disease Stage ◽  
Cellular Plasticity ◽  
Embryonic Origin ◽  
Promote Disease Progression

Cutaneous melanoma represents one of the deadliest types of skin cancer. The prognosis strongly depends on the disease stage, thus early detection is crucial. New therapies, including BRAF and MEK inhibitors and immunotherapies, have significantly improved the survival of patients in the last decade. However, intrinsic and acquired resistance is still a challenge. In this review, we discuss two major aspects that contribute to the aggressiveness of melanoma, namely, the embryonic origin of melanocytes and melanoma cells and cellular plasticity. First, we summarize the physiological function of epidermal melanocytes and their development from precursor cells that originate from the neural crest (NC). Next, we discuss the concepts of intratumoral heterogeneity, cellular plasticity, and phenotype switching that enable melanoma to adapt to changes in the tumor microenvironment and promote disease progression and drug resistance. Finally, we further dissect the connection of these two aspects by focusing on the transcriptional regulators MSX1, MITF, SOX10, PAX3, and FOXD3. These factors play a key role in NC initiation, NC cell migration, and melanocyte formation, and we discuss how they contribute to cellular plasticity and drug resistance in melanoma.

scholarly journals The Ribosomal Protein L28 Gene Is Involved in Sorafenib Resistance in Hepatocellular Carcinoma

2021 ◽  
Author(s):  
Yi Shi ◽  
Xiaojiang Wang ◽  
Qiong Zhu ◽  
Gang Chen
Keyword(s):  
Hepatocellular Carcinoma ◽  
Drug Resistance ◽  
Hepg2 Cells ◽  
Cell Model ◽  
Resistant Cell ◽  
Drug Resistant ◽  
Resistant Gene ◽  
Key Genes ◽  
Resistant Cells

Abstract Background: Sorafenib is the first molecular-targeted drug for the treatment of advanced hepatocellular carcinoma (HCC). However, its treatment efficiency decreases after a short period of time because of the development of drug resistance. This study investigates the role of key genes in regulating sorafenib-resistance in hepatocellular carcinoma and elucidates the mechanism of drug resistance. Methods: The HCC HepG2 cells were used to generate a sorafenib-resistant cell model by culturing the cells in gradually increasing concentration of sorafenib. RNA microarray was applied to profile gene expression and screen key genes associated with sorafenib resistance. Specific targets were knockdown in sorafenib-resistant HepG2 cells for functional studies. The HCC model was established in ACI rats using Morris hepatoma3924A cells to validate selected genes associated with sorafenib resistance in vivo. Results: The HepG2 sorafenib-resistant cell model was successfully established. The IC50 of sorafenib was 9.988mM in HepG2 sorafenib-resistant cells. A total of 35 up-regulated genes were detected by expression profile chip. High-content screening technology was used and a potential drug-resistant gene RPL28 was filtered out. After knocking down of RPL28 in HepG2 sorafenib-resistant cells, the results of cell proliferation and apoptosis illustrated that RPL28 is the key drug-resistant gene in the cells. Furthermore, it was found that both RNA and protein expression of RPL28 increased in HepG2 sorafenib-resistant specimens of Morris Hepatoma rats. In addition, the expression of functional proteins Ki-67 increased in sorafenib-resistant cells. Conclusion: Our study suggested that RPL28 was a key gene for sorafenib resistance in HCC both in vitro and in vivo.

Potential Role of Dual NF-κB and Oxidative Stress Pathway Inhibitor, OT-304 as a Novel Drug Resistance-Reversing Agent.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 4211-4211
Author(s):  
Shaker A. Mousa ◽  
Ghanshyam Patil ◽  
Abdelhadi Rebbaa
Keyword(s):  
Oxidative Stress ◽  
Drug Resistance ◽  
Tumor Cells ◽  
Genetic Alterations ◽  
Potential Candidate ◽  
Drug Resistant ◽  
P Glycoprotein ◽  
And Oxidative Stress

Abstract The development of resistance to chemotherapy represents an adaptive biological response by tumor cells that leads to treatment failure and patient relapse. During the course of their evolution (intrinsic resistance) or in response to chemotherapy (acquired resistance), tumor cells may undergo genetic alterations to possess a drug resistant phenotype. Dysregulation of membrane transport proteins and cellular enzymes, as well as altered susceptibility to commit to apoptosis are among the mechanisms that contribute to the genesis of acquired drug resistance. Recently, the development of approaches to prevent and/or to reverse this phenomenon has attracted special interest and a number of drug candidates have been identified. Despite strong effects observed for these candidates in vitro, however, most of them fail in vivo. In the present study, we have identified a novel small molecule inhibitor of dual NF-κB and oxidative stress pathways, OT-304, as a potential candidate to reverse drug resistance. Initial investigations indicate that this compound effectively inhibits proliferation of doxorubicin-sensitive and doxorubicin-resistant cells to the same extent, suggesting that it is capable of bypassing the development of drug resistance. Additional experiments reveal that OT-304 enhances cancer cell sensitivity to doxorubicin and to etoposide, particularly in cells characterized by the over-expression of the drug transporter P-glycoprotein. These findings suggest that either the expression/and or the function of P-glycoprotein could be affected by OT-304. In vivo studies using tumor xenografts in nude mice showed that OT-304 is also capable of preventing the growth of drug resistant cancer cells. This later finding further confirms the role of OT-304 as a drug resistance-reversing agent and warrants further pre-clinical and clinical investigation to determine its efficacy in treating aggressive tumors.

Targeting Myeloma Cells and Their Progenitors By Pim Kinase Inhibition

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 5724-5724
Author(s):  
Shiro Fujii ◽  
Hirokazu Miki ◽  
Asuka Oda ◽  
Keiichiro Watanabe ◽  
Ryota Amachi ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Drug Resistance ◽  
Abc Transporter ◽  
Therapeutic Target ◽  
Bone Lesions ◽  
Drug Resistant ◽  
Acidic Conditions ◽  
Important Therapeutic Target

Abstract Myeloma (MM) cells grow and expand almost exclusively in the bone marrow while creating a cellular microenvironment suitable for MM cell growth and survival (MM niche). In pursuing the molecular mechanisms whereby MM cells gain drug resistance in the “MM niche”, we have found that the serine/threonine kinase Pim-2 is constitutively over-expressed in MM cells, and further up-regulated by co-cultures with bone marrow stromal cells (BMSCs) as well as osteoclasts (Leukemia, 2011), and that Pim-2 is an important therapeutic target in MM for the progression of MM tumor and bone disease (Leukemia, 2014). The ABC transporter BCRP is preferentially expressed in drug resistant MM cells as well as in MM progenitors or stem cells. BCRP has been demonstrated to be phosphorylated by Pim kinases to trigger its dimerization and function; Pim inhibition may suppress the BCRP function to sensitize BCRP-expressing MM cells to chemotherapeutic agents. In the present study we therefore explored whether Pim inhibition is able to target and impair BCRP-expressing drug-resistant MM cells and MM progenitors. We analyzed an ABC transporter activity in BCRP-expressing RPMI8226 and KMS11 cells by intracellular accumulation and retention of BCRP substrates with auto-fluorescence emission, mitoxantrone and doxorubicin, in flow cytometry. Treatment with Pim inhibitors, SMI-16a or SMI-4a, increased the incorporation of these drugs into the MM cells and enhanced their subsequent intracellular retention after 6-hour incubation without these drugs, although BCRP expression on their surface was only marginally affected by the Pim inhibition. Interestingly, acidic conditions up-regulated Pim-2 expression while reducing the accumulation and retention of these drugs in BCRP-expressing RPMI8226 and KMS11 cells. However, the Pim inhibitors efficaciously restored the drug accumulation and retention reduced by extracellular acidification, and enhanced the cytotoxic activity of the BCRP substrate doxorubicin against RPMI8226 cells rather preferentially in acidic conditions. Furthermore, the Pim inhibition minimized the sizes of “side populations”, highly drug-resistant fractions with enhanced BCRP activity, and the ability of colony formation in RPMI8226 and KMS11 cells, which was more marked in acidic conditions. We previously demonstrated the in vivo effects of the Pim inhibitors in human INA-6 cell-bearing SCID-rab MM models and syngeneic mouse MM models with an intra-tibial inoculation of 5TGM1 MM cells (Leukemia, 2014). To further examine the acid-tropism of anti-tumorigenic activity of Pim inhibition, we pretreated murine 5TGM1 MM cells in vitro with or without SMI16a at pH6.8 for 24 hours, and transplanted to the tibiae in mice the same numbers of viable MM cells remaining in each treatment group. Treatment with SMI16a at pH6.8 almost completely abrogated in vivo tumorigenic capacity of 5TGM1 cells, while MM cells without the treatment rapidly grew and expanded in and outside of the tibiae, suggesting targeting clonogenic MM cells by Pim inhibition preferentially in acidic conditions. Taken together, Pim-2 may become an important therapeutic target of drug-resistant BCRP-expressing MM cells and their progenitors which appear to gain more drug resistance in acidic bone lesions. Combinatory treatment with Pim inhibitors warrants further study to overcome drug resistance in MM cells, including their tumorigenic cancer stem cells. Disclosures No relevant conflicts of interest to declare.

scholarly journals Midkine Mediates Intercellular Crosstalk between Drug-Resistant and Drug-Sensitive Neuroblastoma Cells In Vitro and In Vivo

ISRN Oncology ◽  
2013 ◽  
Vol 2013 ◽  
pp. 1-12
Author(s):  
Fei Chu ◽  
Jessica A. Naiditch ◽  
Sandra Clark ◽  
Yi-Yong Qiu ◽  
Xin Zheng ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Chemotherapy Resistance ◽  
Neuroblastoma Cells ◽  
Cytotoxic Agents ◽  
Drug Resistant ◽  
Wild Type ◽  
Cytoprotective Effect ◽  
Acquired Drug Resistance

Resistance to cytotoxic agents has long been known to be a major limitation in the treatment of human cancers. Although many mechanisms of drug resistance have been identified, chemotherapies targeting known mechanisms have failed to lead to effective reversal of drug resistance, suggesting that alternative mechanisms remain undiscovered. Previous work identified midkine (MK) as a novel putative survival molecule responsible for cytoprotective signaling between drug-resistant and drug-sensitive neuroblastoma, osteosarcoma and breast carcinoma cells in vitro. In the present study, we provide further in vitro and in vivo studies supporting the role of MK in neuroblastoma cytoprotection. MK overexpressing wild type neuroblastoma cells exhibit a cytoprotective effect on wild type cells when grown in a co-culture system, similar to that seen with doxorubicin resistant cells. siRNA knockdown of MK expression in doxorubicin resistant neuroblastoma and osteosarcoma cells ameliorates this protective effect. Overexpression of MK in wild type neuroblastoma cells leads to acquired drug resistance to doxorubicin and to the related drug etoposide. Mouse studies injecting various ratios of doxorubicin resistant or MK transfected cells with GFP transfected wild type cells confirm this cytoprotective effect in vivo. These findings provide additional evidence for the existence of intercellular cytoprotective signals mediated by MK which contribute to chemotherapy resistance in neuroblastoma.

scholarly journals Tirapazamine As a Strategy to Overcome Hypoxia-Induced Drug Resistance in Multiple Myeloma

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 4436-4436
Author(s):  
Barbara Muz ◽  
Pilar De La Puente ◽  
Micah John Luderer ◽  
Farideh Ordikhani ◽  
Abdel Kareem Azab
Keyword(s):  
Multiple Myeloma ◽  
Flow Cytometry ◽  
Drug Resistance ◽  
Cell Survival ◽  
Research Funding ◽  
High Dose ◽  
Drug Resistant ◽  
Hypoxic Conditions

Abstract Introduction: Multiple myeloma (MM) is a lymphoplasmacytic malignancy characterized by the continuous spread of MM cells in and out of the bone marrow (BM). Despite the introduction of novel therapies, cancer patients relapse due to the development of drug resistant cells, which are, at least in part, promoted by hypoxia. Therefore, in this study we aimed to overcome drug resistance in MM by inhibition of the hypoxic responses in these cells. Tirapazamine (TPZ) is a hypoxia-activated pro-drug causing cell apoptosis, which has been shown to improve the outcome of patients with solid tumors when combined with radiotherapy; however, it has not been tested in MM. We used TPZ for the first time in MM to target the drug resistant cancer cells and sensitize them to therapy. Methods: To test the effect of TPZ on tumor survival in vitro, MM cell lines (MM1.s, H929, OPM1, RPMI8226) were exposed to normoxia (21% O2) or hypoxia (1% O2) for 24 hours with different concentrations of TPZ in order to obtain an IC50, and cell survival was assessed using MTT assay. Also, a combination of bortezomib and carfilzomib with or without TPZ was tested on cell survival. For in vivo study, 5 x 106 MM1s-Luc-GFP cells were injected intravenously (IV) into SCID mice and tumor progression was monitored for 3 weeks by bioluminescent imaging. First, we tested the hypoxic status of mice treated with and without a high-dose bortezomib (1.5mg/kg). Pimonidazole (PIM) was injected intraperitoneally (IP) into mice and 4 hours later BM was harvested, stained with anti-PIM-APC antibody and followed by measuring PIM signal in MM1s-GFP+ cells using flow cytometry. Second, we developed drug resistant cells by treating mice with a high-dose bortezomib (1.5mg/kg), and then treated with (1) bortezomib only (0.5mg/kg; n=3), or (2) bortezomib and TPZ (40mg/kg; n=3), all administered IP sequentially twice a week. The number of residual MM1s-GFP+ cells was calculated by flow cytometry. Results: We found that TPZ was active in a dose-dependent manner only in hypoxic conditions in MM cell lines. We showed that residual MM cells in the BM after high-dose bortezomib are hypoxic, as demonstrated by PIM staining. The combination of TPZ with bortezomib and carfilzomib resensitized cancer cells to death in hypoxia, overcoming hypoxia-induced drug resistance in vitro. Moreover, TPZ-treatment in combination with bortezomib further decreased residual MM cells in vivo. Conclusions: We reported that MRD was hypoxic and that TPZ, which was cytotoxic for MM cells only in hypoxic conditions, overcame hypoxia-induced drug resistance in vitro and killed bortezomib-resistant residual MM cells in vivo. This is the first study to show the efficacy of TPZ in MM. This data provides a preclinical basis for future clinical trials testing efficacy of TPZ in MM. Disclosures Azab: Selexys: Research Funding; Karyopharm: Research Funding; Cell Works: Research Funding; Targeted Therapeutics LLC: Other: Founder and owner ; Verastem: Research Funding.

scholarly journals AVA4746, an Orally Available, Clinical Grade Antagonist of Integrin Alpha 4, Sensitizes Pre-B Cell Acute Lymphoblastic Leukemia to Chemotherapy

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 2765-2765 ◽  
Author(s):  
Yongsheng Ruan ◽  
Eun Ji Gang ◽  
Hye-Na Kim ◽  
Chintan Parekh ◽  
Hisham Abdel-Azim ◽  
...  
Keyword(s):  
Overall Survival ◽  
Drug Resistance ◽  
Acute Lymphoblastic Leukemia ◽  
Metabolic Activity ◽  
Research Funding ◽  
Lymphoblastic Leukemia ◽  
Drug Resistant ◽  
Support Research

Abstract Background. Even though remarkable progress has been made in the treatment of childhood acute lymphoblastic leukemia (ALL), salvage of relapse patients remains a challenge. The role of the bone marrow (BM) microenvironment is critical to protect leukemia cells from chemotherapy. The BM microenvironment promotes cell adhesion-mediated drug resistance (CAM-DR) in ALL.We and others have shown that the adhesion molecule integrin α4, referred to hereafter as α4, mediates drug resistance of B-ALL. In our previous studies, we showed that both α4 blockade by natalizumab and inhibition by the small molecule α4 antagonist TBC3486 can sensitize relapsed ALL cells to chemotherapy. However, no α4 targeting therapy is currently clinically available to treat leukemia. Here, we preclinically evaluate a novel non-peptidic small molecule antagonist, AVA4746, which has been safely used in clinical studies, as a potential new approach to combat drug resistant ALL. Method. Six refractory or relapsed primary pre-B ALL cases were used for in vitro studies. Viability was assessed by trypan blue counts or annexin V/7AAD flow cytometric analysis and metabolic activity was evaluated by Cytoscan WST-1 assay. For in vivo evaluation a NOD/SCID IL2Rγ-/- xenograft model of primary pre-B ALL (LAX7R) was used.AVA4746 (15mg/kg) was administered by oral gavage twice a day continuously for 14 days, and vincristine, dexamethasone, L-asparaginase (VDL) was given intraperitoneally (weekly) for 4 weeks. Overall survival was determined by Kaplan-Meier Survival analysis. Results. AVA4746 caused a significant decrease in mean fluorescence intensity (MFI) of α4 expression in six out of six ALL cases at doses of both 5μM and 25μM after 24 hours and 96 hours compared to DMSO control. Interestingly, decreased protein expression of α4 was also observed by Western Blot analysis all six ALL cases. We tested next in two cases (LAX53, ICN13), if AVA4746 de-adheres ALL cells from its counter receptor VCAM-1. The percentages of adherence after treatment with AVA4746 (25μM) were significantly lower than after DMSO treatment (10.3%±4.9% vs. 99.9%±7.6%, p= 0.00007 for LAX7R; 8.1%±1.0% vs. 100.1%±13.6%, p= 0.0003 for LAX53; 9.0%±1.6% vs. 100.0%±14.0%, p=0.0004 for ICN13). AVA4746 was not associated with apoptosis in vitro alone or in combination with chemotherapy (VDL). Metabolic activity as assessed by WST-1 assay was markedly decreased by AVA4746 in two of two ALL cases. AVA4746 also decreased ALL proliferation in two out of two ALL samples tested. In vivo, AVA4746 in combination with VDL chemotherapy treatment led to significant prolongation of overall survival (n=6) compared with the VDL only treated group (n=6) (MST= 78.5 days vs MST= 68 days; P<0.05). There was no significant difference in survival between the PBS control group (n=5) and the AVA4746 mono-treatment group (n=5) (MST=38days vs MST= 38days). Conclusion. We have identified α4 as a central adhesion molecule in CAM-DR of ALL and have shown that AVA-4746, an orally available and specific α4 antagonist, which has been safely used in clinical studies, downregulates α4 in primary ALL and functionally de-adheres them from VCAM-1. Critically, we demonstrated that inhibition of α4 in combination with standard chemotherapy can prolong the survival of NSG mice bearing pre-B ALL. These data support further study of inhibition of α4 using AVA4746 as a novel strategy to treat drug resistant B lineage ALL. Disclosures Bhojwani: Amgen: Other: Blinatumumab global pediatric advisory board 2015. Wayne:Spectrum Pharmaceuticals: Honoraria, Other: Travel Support, Research Funding; Kite Pharma: Honoraria, Other: Travel support, Research Funding; Pfizer: Consultancy, Honoraria, Other: Travel Support; Medimmune: Honoraria, Other: Travel Support, Research Funding; NIH: Patents & Royalties. Kim:Antisense Therapeutics Ltd: Patents & Royalties.

Heterogeneity and Phenotypic Instability of Chemotherapeutic and Immunologic Sensitivity in Murine and Human Melanoma Cell Clones

1992 ◽  
Vol 78 (1) ◽  
pp. 5-9 ◽  
Author(s):  
Rosanna Supino ◽  
Monica Rodolfo ◽  
Mariangela Mariani ◽  
Elena Mapelli
Keyword(s):  
Drug Resistance ◽  
Melanoma Cell ◽  
Drug Sensitivity ◽  
Human Melanoma ◽  
Lak Cells ◽  
Human Melanoma Cell ◽  
Drug Resistant ◽  
Drug Induced ◽  
Resistant Cells

The aim of the present study was to examine the phenotypic heterogeneity of murine and human melanoma cell lines with particular reference to anticancer drug sensitivity, growth pattern and susceptibility to lysis by lymphokine (rIL2) activated killer (LAK cells). Clones selected for a different drug sensitivity were tested to evaluate the stability of such properties after different in vitro passages. A possible relationship between drug sensitivity and LAK susceptibility was also analyzed. The results indicated a high heterogeneity in murine and in human melanoma clones for all the parameters. However, drug sensitivity, which was stable although for only a few passages in an untreated human melanoma, was highly unstable in murine naturally or drug-induced resistant cells. Finally, whereas human drug-resistant clones were sensitive to lysis by LAK cells and an inverse correlation was found with the level of drug resistance, murine clones appeared to be LAK sensitive, and no correlation was found between the level of drug resistance and LAK sensitivity. Our data indicate a different stability in drug response of human and murine cells and a different behaviour of human and murine drug-resistant cells in response to LAK lysis.

Drug Resistance and Dormancy Represent Reversible Characteristics in Patients' ALL Cells Growing in Mice

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 602-602
Author(s):  
Erbey Ziya Özdemir ◽  
Sarah Ebinger ◽  
Christoph Ziegenhain ◽  
Wolfgang Enard ◽  
Olivier Gires ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Drug Resistance ◽  
Treatment Strategies ◽  
Preclinical Model ◽  
Bone Marrow Niche ◽  
Drug Resistant ◽  
Novel Treatment ◽  
Dormant Cells

Abstract Introduction Drug resistant cells represent a major threat for tumor patients as they might induce relapse and severely decrease disease outcome. Relapse represents a major drawback in patients with acute lymphoblastic leukemia (ALL), the single most frequent malignancy in children. Novel treatment options are intensively desired to remove drug resistant cells, which often additionally display dormancy. Aim We aimed at unraveling basic mechanisms determining drug resistance and dormancy, as basis for developing novel treatment strategies to prevent relapse. Methods Using cutting edge in vivo technology, we performed genetic engineering in the individualized xenograft mouse model of ALL. Primary patients' ALL cells were amplified in mice to generate patient-derived xenograft (PDX) cells. ALL PDX cells were lentivirally transduced to express transgenes. Recombinant luciferase allowed highly sensitive and reliable follow-up of leukemia growth and treatment. Recombinant surface markers enabled an unbiased approach to reliably and effectively enriching minute numbers of PDX cells from mouse bone marrow. Two independent, complementary innovative preclinical in vivo mouse models were established.In the first model, proliferation sensitive dyes allowed identifying and enriching in vivo long-term dormant PDX ALL cells.In the second model, the clinically highly relevant and challenging situation of MRD was mimicked in mice. PDX ALL cells were grown to advanced leukemia stages of above 30 % human blasts in bone marrow, when systemic chemotherapy with conventional cytotoxic drugs was initiated for prolonged periods of time, similar as applied in ALL patients. Chemotherapy reduced advanced leukemia down to 0,1 % or 10-3 leukemia cells in bone marrow, resembling not only complete morphologic remission, but even molecular remission. This novel preclinical model allows for the first time to characterize patients' dormant and MRD cells in detail including functional in vivo assays. Results Using our innovative preclinical model of dormancy, we identified a novel, distinct, rare subpopulation of PDX ALL cells that displayed long term dormancy in vivo. Long-term dormant cells showed significant resistance against drug treatment in vivo, as therapy nearly exclusively targeted proliferating cells. Dormant cells showed stem cell behavior as they initiated leukemia upon re-transplantation into further recipient mice. Long-term dormant cells thus combined the three challenging characteristics of relapse-inducing cells dormancy, drug resistance and stemness with re-growth upon withdrawal of treatment pressure. Using our second novel preclinical model, we isolated a pure, vivid fraction of rare MRD cells. These cells showed drug resistance in vivo and stemness features. We used single cell RNA sequencing to compare the transcriptomes of dormant and MRD populations and found that they were highly similar. Both populations had further similarities with primary high-risk ALL cells and dormant sub-fractions in patients' leukemia samples. Of high relevance for future treatment strategies, both, dormancy and drug resistance revealed transient characteristics in PDX ALL cells. When PDX long-term dormant ALL cells were distracted from their in vivo environment, they started proliferating similarly as their previously highly proliferative counterparts. When in vivo drug resistant PDX ALL cells were retrieved from murine bone marrow, they showed similar drug sensitivity in vitro as their sensitive counterparts. Summary/Conclusion Thus, both in vivo dormancy and drug resistance represent reversible characteristics in ALL cells which might result from the localization of ALL cells in the bone marrow niche. Dissolving ALL cells from their in vivo environment might sensitize them towards treatment. Addressing and inhibiting the interaction between ALL cells and their bone marrow niche might represent an attractive future therapeutic strategy to prevent ALL relapse. Disclosures No relevant conflicts of interest to declare.

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