Despite decades of research and successful improvements in diagnosis and therapy, prostate cancer (PC) remains a major challenge. In recent years, it has become clear that PC stem cells (PCSCs) are ...the driving force in tumorigenesis, relapse, metastasis, and therapeutic resistance of PC. In this minireview, we discuss the impact of PCSCs in the clinical practice. Moreover, new therapeutic approaches to combat PCSCs are presented with the aim to achieve an improved outcome for patients with PC.
Transitions between epithelial and mesenchymal phenotypes - the epithelial to -mesenchymal transition (EMT) and its reverse the mesenchymal to epithelial transition (MET) - are hallmarks of cancer ...metastasis. While transitioning between the epithelial and mesenchymal phenotypes, cells can also attain a hybrid epithelial/mesenchymal (E/M) (i.e., partial or intermediate EMT) phenotype. Cells in this phenotype have mixed epithelial (e.g., adhesion) and mesenchymal (e.g., migration) properties, thereby allowing them to move collectively as clusters. If these clusters reach the bloodstream intact, they can give rise to clusters of circulating tumor cells (CTCs), as have often been seen experimentally. Here, we review the operating principles of the core regulatory network for EMT/MET that acts as a "three-way" switch giving rise to three distinct phenotypes - E, M and hybrid E/M - and present a theoretical framework that can elucidate the role of many other players in regulating epithelial plasticity. Furthermore, we highlight recent studies on partial EMT and its association with drug resistance and tumor-initiating potential; and discuss how cell-cell communication between cells in a partial EMT phenotype can enable the formation of clusters of CTCs. These clusters can be more apoptosis-resistant and have more tumor-initiating potential than singly moving CTCs with a wholly mesenchymal (complete EMT) phenotype. Also, more such clusters can be formed under inflammatory conditions that are often generated by various therapies. Finally, we discuss the multiple advantages that the partial EMT or hybrid E/M phenotype have as compared to a complete EMT phenotype and argue that these collectively migrating cells are the primary "bad actors" of metastasis.
Mechanisms of cancer stem cell therapy Akbar Samadani, Ali; Keymoradzdeh, Arman; Shams, Shima ...
Clinica chimica acta,
November 2020, 2020-11-00, Letnik:
510
Journal Article
Recenzirano
•Cancer stem cells (CSCs) are responsible for carcinogenesis and involved in the drug and radiation resistance, metastasis, tumor relapse and also tumor initiation.•mTOR, SHH, NOTCH, and Wnt/ ...β-catering are involved in regulating the CSCs colonies progression and drug resistance and are associated in CSCs targeted cancers therapies.•CSC hypothesis prepares an impressive and significant pattern in clinical oncology and the tumor heterogeneity.•Programming and designing the new and practical methods for correct separation, recognition and target CSCs is a very important note in therapy.
Cancer stem cells (CSCs) are responsible for carcinogenesis and tumorigenesis and are involved in drug and radiation resistance, metastasis, tumor relapse and initiation. Remarkably, they have other abilities such as inheritance of self-renewal and de-differentiation. Hence, targeting CSCs is considered a potential anti-cancer therapeutic strategy. Recent advances in the identification of biomarkers to recognize CSCs and the development of new techniques to evaluate tumorigenic and carcinogenic roles of CSCs are instrumental to this approach. Elucidation of signaling pathways that regulate CSCs colony progression and drug resistance are critical in establishing effective targeted therapies. CSCs play a central key role in immunomodulation, immune evasion and effector immunity, which alters immune system balancing. These include mTOR, SHH, NOTCH and Wnt/β-catering in cancer progression. In this review article, we discuss the importance of these CSCs pathways in cancer therapy.
Cancer stem cell (CSC) biology and tumor immunology have shaped our understanding of tumorigenesis. However, we still do not fully understand why tumors can be contained but not eliminated by the ...immune system and whether rare CSCs are required for tumor propagation. Long latency or recurrence periods have been described for most tumors. Conceptually, this requires a subset of malignant cells which is capable of initiating tumors, but is neither eliminated by immune cells nor able to grow straight into overt tumors. These criteria would be fulfilled by CSCs. Stem cells are pluripotent, immune-privileged, and long-living, but depend on specialized niches. Thus, latent tumors may be maintained by a niche-constrained reservoir of long-living CSCs that are exempt from immunosurveillance while niche-independent and more immunogenic daughter cells are constantly eliminated. The small subpopulation of CSCs is often held responsible for tumor initiation, metastasis, and recurrence. Experimentally, this hypothesis was supported by the observation that only this subset can propagate tumors in non-obese diabetic/scid mice, which lack T and B cells. Yet, the concept was challenged when an unexpectedly large proportion of melanoma cells were found to be capable of seeding complex tumors in mice which further lack NK cells. Moreover, the link between stem cell-like properties and tumorigenicity was not sustained in these highly immunodeficient animals. In humans, however, tumor-propagating cells must also escape from immune-mediated destruction. The ability to persist and to initiate neoplastic growth in the presence of immunosurveillance - which would be lost in a maximally immunodeficient animal model - could hence be a decisive criterion for CSCs. Consequently, integrating scientific insight from stem cell biology and tumor immunology to build a new concept of "CSC immunology" may help to reconcile the outlined contradictions and to improve our understanding of tumorigenesis.
Abstract
BACKGROUND. The prognosis of glioblastoma (GBM) treated with standard-of-care regimens remains very poor with a median time to recurrence of 7-9 months, and a median survival of 15-18 ...months. GBMs contain a small, but resilient population of cancer stem cells (CSCs) that contribute to tumor initiation, maintenance, and therapy resistance. For these reasons, its is extremely important to determine the sensitivity of CSCs to chemotherapeutic agents, with the intent of identifying more effective treatment protocols which would then translate into improved clinical survival. METHODS. We have used a novel CLIA and CAP-accredited Cancer Stem Cell Cytotoxicity Assay (ChemoID) to guide treatment for 55 Grade III and Grade IV glioma patients with the most efficacious chemotherapy treatments from a panel of FDA approved drugs or their combinations. Patients were evaluated by MRI scans and response was assessed according to RANO criteria. RESULTS: We report here a prospective clinical investigation using the ChemoID assay to measure the sensitivity and resistance of CSCs and bulk of tumor cells cultured from 55 GBM clinical specimens challenged with several chemotherapy agents, which were also correlated to the clinical response of the treated patients, independently of other biomarkers. The median recurrence time was 15 months for patients with a sensitive (>40% cell kill) CSCs test versus only 6 months for patients with a resistant CSCs test. CONCLUSIONS. The data suggests that GBM patients treated with CSC Cytotoxicity Assay-guided responsive drugs have delayed time to recurrence and the assay has the potential to help tailor chemotherapy choices to improve clinical outcomes.
Abstract
BACKGROUND
Profound heterogeneity has severely hampered therapeutic advancements in glioblastoma (GBM). Remarkably, GBM exhibits broad clinical and histopathologic overlaps suggesting the ...presence of a common regulatory state. The GBM state embodies restructuring of the master regulatory gene network (MRGN) forced by founding mutations and perpetuated in subclones of GBM stem-like cells (GSC). Successful targeting and altering of the MRGN promise to circumvent the heterogeneity.
METHODS
To decipher the common MRGN in GSC, we applied a robust AI suite, NETZEN, that integrates deep neural networks with gene network-based ranking to the reference GBM network generated using TCGA’s entire GBM RNAseq dataset and a dataset containing > 30 diverse GSC and paired GBM differentiated cell lines, 6 normal astrocyte and 3 normal neuronal precursor cell lines. To develop a gene therapy against the MRGN, we performed a screen of a rAAV capsid library using GBM patient-derived orthotopic xenografts (PDX) to identify capsid variants with specific tropism for GBM cells to deliver shRNA-based cassettes.
RESULTS
We discovered a putative MRGN in GSC, anchored by developmentally restricted master regulators (MR). To confirm its critical role, we deconstructed it using shRNA in a panel of PDX and uniformly observed attenuated tumor growth and mortality compared to controls (p < 0.05 in all lines). More notably, when normal astrocytes were forced to reconstruct the MRGN, transformation into GSC-like cells occurred, as measured by single-cell analysis, sphere formation in vitro, and most importantly, development of lethal infiltrating brain tumors in 15/15 mice. Finally, selected novel AAV capsids with 10-40-fold higher specificity for GBM cells were utilized in a shRNA-based AAV platform to target key MR in the validated MRGN.
CONCLUSIONS
The GBM state is established by a developmental subnetwork permitting a first-of-its-kind, heterogeneity-agnostic AAV-based treatment approach. This AI-directed R&D program can be expanded to target other cancers.
Abstract
Glioblastoma (GBM) is a dismal disease and despite optimal treatment, long-term survival remains uncommon. Molecular classification revealed three distinct GBM subgroups and has helped to ...shine light on the tumor’s inter/intratumoral heterogeneity. Interestingly, recent evidence shows plasticity between these subtypes in which the proneural (PN) glioma stem-like cells undergo transition into the more aggressive mesenchymal (MES) subtype leading to therapeutic resistance. Extracellular vesicles (EVs) are considered a heterogeneous group of membrane-limited vesicles secreted by nearly every cell. In the context of GBM, these biological nanoparticles act as multifunctional signaling complexes and play an important role in intercellular communication allowing cancer cells to exchange information with each other, the tumor microenvironment, and distant cells. We show that MES cells derived EVs modulate PN cells to increase migratory potential, stemness, invasiveness, aggressiveness, and therapeutic resistance by inducing mesenchymal transition through NF-KB/STAT3 signaling. Furthermore, we shine light on the role of EVs derived from irradiated GBM cells and their potential impact on microglia and resulting treatment resistance.
Abstract
Intratumoral heterogeneity is one of the major barriers in the treatment of many tumor types. In glioblastoma (GBM) – the most aggressive brain tumor - survival of patients following ...standard therapy has stagnated to an average of 14 months, largely due to the inherent heterogeneity and phenotypic plasticity. Patient-derived orthotopic xenografts (PDOX) are important tools for preclinical cancer studies. We have shown that they recapitulate histological and molecular features of patient tumors, thus producing more clinically relevant study outcomes when compared to other preclinical models. To understand the impact of treatment on intratumoral heterogeneity and interactions of tumor cells with the microenvironment, we applied single-cell RNA-seq in GBM PDOX models generated from naive and treatment exposed patient tumors. Here we show that PDOX models recapitulate all the major cell types and transcriptional programs reported in GBM patient samples. We demonstrate that GBM tumor cells occur in distinct phenotypic states dictated by microenvironmental cues and treatment-induced pressure. Non-neoplastic cells present within xenografts undergo transcriptomic adaptation similar to the GBM microenvironment in patients. Analysis of treated PDOXs and longitudinal PDOX models derived from patients prior and after treatment allows us to investigate short-term and stable long-term transcriptomic adaptations. We aim to reveal key molecular regulators enhancing tumor cell plasticity and resistance, that could be targeted in combinatory treatments. Our GBM PDOX models provide a platform for high-quality pre-clinical research and an improved clinical relevance in the development and testing of novel therapeutics.
Abstract
INTRODUCTION
Release of exosomes and extracellular vesicles (EV) by glioblastomas plays key roles in modulating the tumor microenvironment and therapeutic response. Studies to date have ...largely focused on the impact of EV and exosomes on the recipient cell. Here, we demonstrate that EV-mediated export of a master-regulatory miRNA has fate-determining impacts on the cell releasing the EVs.
METHODS
microRNA (miRNA) profiling was performed using clinical glioblastoma specimens from the same patients derived pre- and post-standard of care treatment. Mechanism mediating altered miRNA homeostasis were assessed.
RESULTS
While the levels of nearly all miRNAs remained unchanged after standard-of-care treatment, decreased levels of few, select miRNAs were observed, including miR-603. In response to ionizing radiation (IR), but not temozolomide (TMZ), glioblastoma cell lines exhibited a time-dependent decrease in miR-603 levels. While miR-603 biogenesis and degradation remained unchanged after IR, IR induced an increase in EV-mediated export of miR-603. Profiling of miR-603 targets revealed that miR-603 repressed the insulin-like growth factor 1 (IGF1) and IGF1 receptor (IGF1R), genes required to maintain the cancer stem cell (CSC) state, as well as MGMT, the gene encoding a DNA repair protein that detoxifies temozolomide (TMZ) induced DNA damages. IR induced export of miR-603 de-repress IGF1/IGF1R to promote radiation resistance and de-repress MGMT to promote cross-resistance to TMZ and CCNU. Ectopic miR-603 expression overwhelmed cellular capacity for miR-603 export and synergized with the tumoricidal effects of IR and temozolomide (TMZ).
CONCLUSIONS
Radiation stimulated EV-mediated export of miR-603 to facilitate acquired resistance to IR and cross-resistance to DNA alkylating agents.
Abstract
BACKGROUND
The incidence of brain metastases (BM) is tenfold higher than primary brain tumors. BM commonly originate from primary lung, breast, and melanoma tumors with a 90% mortality rate ...within one year of diagnosis. Current standard of care for BM includes surgical resection with concurrent chemoradiation, but does not extend median survival past 16 months, posing a large unmet need to identify novel therapies against BM.
METHODS
From a large in-house biobank of patient-derived BM cell lines, the Singh Lab has generated murine orthotopic patient-derived xenograft (PDX) models of lung, breast, and melanoma BM that recapitulate the stages of BM progression as seen in humans. Using these three PDX models, we identified a population of “pre-metastatic” brain metastasis-initiating cells (BMICs) that are newly arrived in the brain but have yet to form detectable tumors. Pre-metastatic BMICs are not detectable in human patients but are important therapeutic targets with the potential to prevent BM in at-risk patients.
RESULTS
RNA sequencing of pre-metastatic BMICs from all three PDX primary tumor models with subsequent Connectivity Map analysis identified novel compounds that have the potential of killing all three types of BMICs. In particular, we identified two compounds that have selective killing of BMICs in vitro from all three primary tumor cohorts while sparing non-cancerous cells. We further characterized their ability to inhibit the self-renewal and proliferative properties of BMICs. Ongoing in vivo work will investigate the compounds’ preclinical utilities in preventing BM.
CONCLUSION
Identification of novel small molecules that target BMICs could prevent the formation of BM completely and dramatically improve the prognosis of at-risk cancer patients.
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