bims-tucedo Biomed News
on Tumor cell dormancy
Issue of 2022‒01‒02
twenty-two papers selected by
Isabel Puig Borreil
Vall d’Hebron Institute of Oncology

  1. Cancer Res. 2021 Dec 29. pii: canres.1230.2021. [Epub ahead of print]
      Tumor dormancy is a stage in which residual cancer cells remain inactive, but regrowth of dormant cancer cells contributes to recurrence. The complex ecosystem in cancer that promotes cell survival and the factors that eventually overcome growth constraints and result in proliferation remain to be fully elucidated. Doing so may provide new insights and help identify novel strategies to prolong cancer dormancy and prevent disease recurrence. To dissect the molecular pathways and the microenvironments involved in regulation of dormancy, we utilized a novel immunocompetent transgenic model to study minimal residual disease and relapse. This model revealed a significant reorganization of cancer cell structures, stroma, and immune cells with cancer cells showing dormant cell signatures. Single-cell RNA sequencing uncovered remodeling of myeloid and lymphoid compartments. Additionally, the Jagged-1/Notch signaling pathway was shown to regulate many aspects of tumorigenesis, including stem cell development, epithelial-mesenchymal transition, and immune cell homeostasis during minimal residual disease. Treatment with an anti-Jagged-1 antibody inhibited the Jagged-1/Notch signaling pathway in tumor cells and the microenvironment, delaying tumor recurrence. These findings uncover a cascade of regulatory changes in the microenvironment during dormancy and identify a therapeutic strategy to undercut these changes.
  2. Cancer Res. 2021 Dec 29. pii: canres.2342.2021. [Epub ahead of print]
      Dormant cancer cells that survive anti-cancer therapy can lead to cancer recurrence and disseminated metastases that prove fatal in most cases. Recently, specific dormant polyploid giant cancer cells (PGCC) have drawn our attention because of their association with the clinical risk of nasopharyngeal carcinoma (NPC) recurrence, as demonstrated by previous clinical data. In this study, we report the biological properties of PGCC, including mitochondrial alterations, and reveal that autophagy is a critical mechanism of PGCC induction. Moreover, pharmacological or genetic inhibition of autophagy greatly impaired PGCC formation, significantly suppressing metastasis and improving survival in a mouse model. Mechanistically, chemotherapeutic drugs partly damaged mitochondria, which then produced low ATP levels and activated autophagy via the AMPK-mTOR pathway to promote PGCC formation. Analysis of the transcriptional and epigenetic landscape of PGCC revealed overexpression of RIPK1, and the scaffolding function of RIPK1 was required for AMPK-mTOR pathway-induced PGCC survival. High numbers of PGCCs correlated with shorter recurrence time and worse survival outcomes in NPC patients. Collectively, these findings suggest a therapeutic approach of targeting dormant PGCCs in cancer.
  3. EMBO Mol Med. 2021 Dec 27. e11814
      Resistance to BRAF/MEK inhibitor therapy in BRAFV600 -mutated advanced melanoma remains a major obstacle that limits patient benefit. Microenvironment components including the extracellular matrix (ECM) can support tumor cell adaptation and tolerance to targeted therapy; however, the underlying mechanisms remain poorly understood. Here, we investigated the process of matrix-mediated drug resistance (MMDR) in response to BRAFV600 pathway inhibition in melanoma. We demonstrate that physical and structural cues from fibroblast-derived ECM abrogate anti-proliferative responses to BRAF/MEK inhibition. MMDR is mediated by drug-induced linear clustering of phosphorylated DDR1 and DDR2, two tyrosine kinase collagen receptors. Depletion and pharmacological targeting of DDR1 and DDR2 overcome ECM-mediated resistance to BRAF-targeted therapy. In xenografts, targeting DDR with imatinib enhances BRAF inhibitor efficacy, counteracts drug-induced collagen remodeling, and delays tumor relapse. Mechanistically, DDR-dependent MMDR fosters a targetable pro-survival NIK/IKKα/NF-κB2 pathway. These findings reveal a novel role for a collagen-rich matrix and DDR in tumor cell adaptation and resistance. They also provide important insights into environment-mediated drug resistance and a preclinical rationale for targeting DDR signaling in combination with targeted therapy in melanoma.
    Keywords:  DDR; NF-κB2; extracellular matrix; melanoma; therapeutic resistance
  4. Drug Resist Updat. 2021 Dec 16. pii: S1368-7646(21)00057-1. [Epub ahead of print] 100797
      Despite an increasing arsenal of anticancer therapies, many patients continue to have poor outcomes due to the therapeutic failures and tumor relapses. Indeed, the clinical efficacy of anticancer therapies is markedly limited by intrinsic and/or acquired resistance mechanisms that can occur in any tumor type and with any treatment. Thus, there is an urgent clinical need to implement fundamental changes in the tumor treatment paradigm by the development of new experimental strategies that can help to predict the occurrence of clinical drug resistance and to identify alternative therapeutic options. Apart from mutation-driven resistance mechanisms, tumor microenvironment (TME) conditions generate an intratumoral phenotypic heterogeneity that supports disease progression and dismal outcomes. Tumor cell metabolism is a prototypical example of dynamic, heterogeneous, and adaptive phenotypic trait, resulting from the combination of intrinsic [(epi)genetic changes, tissue of origin and differentiation dependency] and extrinsic (oxygen and nutrient availability, metabolic interactions within the TME) factors, enabling cancer cells to survive, metastasize and develop resistance to anticancer therapies. In this review, we summarize the current knowledge regarding metabolism-based mechanisms conferring adaptive resistance to chemo-, radio-and immunotherapies as well as targeted therapies. Furthermore, we report the role of TME-mediated intratumoral metabolic heterogeneity in therapy resistance and how adaptations in amino acid, glucose, and lipid metabolism support the growth of therapy-resistant cancers and/or cellular subpopulations. We also report the intricate interplay between tumor signaling and metabolic pathways in cancer cells and discuss how manipulating key metabolic enzymes and/or providing dietary changes may help to eradicate relapse-sustaining cancer cells. Finally, in the current era of personalized medicine, we describe the strategies that may be applied to implement metabolic profiling for tumor imaging, biomarker identification, selection of tailored treatments and monitoring therapy response during the clinical management of cancer patients.
    Keywords:  Cancer metabolism; Glycolysis; Intratumor heterogeneity; Metabolic plasticity; Oxidative phosphorylation; Therapy resistance; Tumor microenvironment
  5. Cancer Res. 2021 Dec 29. pii: canres.2101.2021. [Epub ahead of print]
      Squamous cell carcinoma driven by human papillomavirus (HPV) is more sensitive to DNA-damaging therapies than its HPV-negative counterpart. Here we show that p16, the clinically utilized surrogate for HPV positivity, renders cells more sensitive to radiation via a ubiquitin-dependent signaling pathway, linking high levels of this protein to increased activity of the transcription factor SP1, increased HUWE1 transcription, and degradation of ubiquitin-specific protease 7 (USP7) and TRIP12. Activation of this pathway in HPV-positive disease led to decreased homologous recombination (HR) and improved response to radiation, a phenomenon that can be recapitulated in HPV-negative disease using USP7 inhibitors in clinical development. This p16-driven axis induced sensitivity to PARP inhibition and potentially leads to "BRCAness" in head and neck squamous cell carcinoma (HNSCC) cells. Thus, these findings support a functional role for p16 in HPV-positive tumors in driving response to DNA damage, which can be exploited to improve outcomes in both HPV-positive and HPV-negative HNSCC patients.
  6. Gastroenterology. 2021 Dec 27. pii: S0016-5085(21)04165-2. [Epub ahead of print]
      BACKGROUND & AIMS: N6-methyladenosine (m6A) governs the fate of RNAs through m6A readers. Colorectal cancer (CRC) exhibits aberrant m6A modifications and expression of m6A regulators. However, how m6A readers interpret oncogenic m6A methylome to promote malignant transformation remains to be illustrated.METHODS: Ythdf1 knockout mouse was generated to determine the effect of Ythdf1 in CRC tumorigenesis in vivo. Multiomic analysis of RNA-sequencing, m6A methylated RNA immunoprecipitation sequencing, YTHDF1 RNA immunoprecipitation sequencing and proteomics were performed to unravel targets of YTHDF1 in CRC. The therapeutic potential of targeting YTHDF1-m6A-ARHGEF2 was evaluated using siRNA encapsulated by lipid nanoparticles (LNP).
    RESULTS: DNA copy number gain of YTHDF1 is a frequent event in CRC and contributes to its overexpression. High expression of YTHDF1 is significantly associated with metastatic gene signature in patient tumors. Ythdf1 knockout in mice dampened tumor growth in an inflammatory CRC model. YTHDF1 promotes cell growth in CRC cell lines and primary organoids, and lung and liver metastasis in vivo. Integrative multiomics analysis identified RhoA activator ARHGEF2 as a key downstream target of YTHDF1. YTHDF1 binds to m6A sites of ARHGEF2 mRNA, resulting in enhanced translation of ARHGEF2. Ectopic expression of ARHGEF2 restored impaired RhoA signaling, cell growth and metastatic ability both in vitro and in vivo caused by YTHDF1 loss, verifying that ARHGEF2 is a key target of YTHDF1. Finally, ARHGEF2 siRNA delivered by LNP significantly suppressed tumor growth and metastasis in vivo.
    CONCLUSIONS: We identify a novel oncogenic epitranscriptome axis of YTHDF1-m6A-ARHGEF2, which regulates CRC tumorigenesis and metastasis. siRNA-delivering LNP drug validated the therapeutic potential of targeting this axis in CRC.
    Keywords:  ARHGEF2; N6-methyladenosine; YTHDF1; colorectal cancer; nanoparticle
  7. Nat Cancer. 2021 Dec;2(12): 1387-1405
      Secreted extracellular vesicles (EVs) influence the tumor microenvironment and promote distal metastasis. Here, we analyzed the involvement of melanoma-secreted EVs in lymph node pre-metastatic niche formation in murine models. We found that small EVs (sEVs) derived from metastatic melanoma cell lines were enriched in nerve growth factor receptor (NGFR, p75NTR), spread through the lymphatic system and were taken up by lymphatic endothelial cells, reinforcing lymph node metastasis. Remarkably, sEVs enhanced lymphangiogenesis and tumor cell adhesion by inducing ERK kinase, nuclear factor (NF)-κB activation and intracellular adhesion molecule (ICAM)-1 expression in lymphatic endothelial cells. Importantly, ablation or inhibition of NGFR in sEVs reversed the lymphangiogenic phenotype, decreased lymph node metastasis and extended survival in pre-clinical models. Furthermore, NGFR expression was augmented in human lymph node metastases relative to that in matched primary tumors, and the frequency of NGFR+ metastatic melanoma cells in lymph nodes correlated with patient survival. In summary, we found that NGFR is secreted in melanoma-derived sEVs, reinforcing lymph node pre-metastatic niche formation and metastasis.
    Keywords:  CD271; NGFR; cell adhesion; lymph node metastasis; lymphangiogenesis; melanoma metastasis; metastasis mechanisms; p75NTR; pre-metastatic niche formation; small extracellular vesicles
  8. Cancer Res. 2021 Dec 28. pii: canres.2988.2021. [Epub ahead of print]
      Docetaxel-based chemotherapy is a standard-of-care treatment for metastatic prostate cancer (PCa), and chemoresistance remains a major challenge in clinical practice. Recent studies have demonstrated that circular RNAs (circRNAs) play critical roles in the development and progression of PCa. However, the biological roles and potential functions of circRNAs in mediating docetaxel-resistant PCa have yet to be well elucidated. In this study, we analyzed the expression profiles of circRNAs in docetaxel-resistant and -sensitive PCa cells through RNA sequencing and found that expression of circARHGAP29 was significantly upregulated in docetaxel-resistant cell lines and clinical samples. Ectopic expression of circARHGAP29 triggered docetaxel resistance and aerobic glycolysis in PCa cells, which was reduced by silencing circARHGAP29. Moreover, eukaryotic initiation factor 4A3 (EIF4A3), which bound the back-spliced junction site and the downstream flanking sequence of circARHGAP29, induced cyclization and cytoplasmic export of circARHGAP29. circARHGAP29 increased the stability of lactate dehydrogenase A (LDHA) mRNA by strengthening its interaction with insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2), leading to enhanced glycolytic metabolism. In addition, circARHGAP29 interacted with and stabilized c-Myc mRNA and protein, which further increased LDHA expression by facilitating its transcription. These findings reveal the crucial function of circARHGAP29 in PCa glycolysis by increasing and stabilizing LDHA mRNA, providing a promising therapeutic target in docetaxel-resistant PCa.
  9. Clin Cancer Res. 2021 Dec 29. pii: clincanres.2389.2021. [Epub ahead of print]
      PURPOSE: CALGB 80405 compared the combination of first-line chemotherapy with cetuximab or bevacizumab in the treatment of advanced or metastatic colorectal cancer (mCRC). While similar clinical outcomes were observed in the cetuximab-chemotherapy group and the bevacizumab-chemotherapy group, biomarkers could identify patients deriving more benefit from either biologic agent.EXPERIMENTAL DESIGN: In this exploratory analysis, the Angiome, a panel of 24 soluble protein biomarkers were measured in baseline plasma samples in CALGB 80405. Prognostic biomarkers were determined using univariate Cox proportional hazards models. Predictive biomarkers were identified using multivariable Cox regression models including interaction between biomarker level and treatment.
    RESULTS: In the total population, high plasma levels of Ang-2, CD73, HGF, ICAM-1, IL-6, OPN, TIMP-1, TSP-2, VCAM-1, and VEGF-R3 were identified as prognostic of worse progression-free survival (PFS) and overall survival (OS). PlGF was identified as predictive of lack of PFS benefit from bevacizumab (bevacizumab HR = 1.51, 95% CI 1.10-2.06; cetuximab HR = 0.94, 95% CI 0.71-1.25; Pinteraction = 0.0298) in the combined FOLFIRI/FOLFOX regimens. High levels of VEGF-D were predictive of lack of PFS benefit from bevacizumab in patients receiving FOLFOX regimen only (FOLFOX/bevacizumab HR = 1.70, 95% CI 1.19-2.42; FOLFOX/cetuximab HR = 0.92, 95% CI 0.68-1.24; Pinteraction = 0.0097).
    CONCLUSIONS: In this exploratory, hypothesis-generating analysis, the Angiome identified multiple prognostic biomarkers and two potential predictive biomarkers for mCRC patients enrolled in CALGB80405. PlGF and VEGF-D predicted lack of benefit from bevacizumab in a chemo-dependent manner.
  10. Cell Rep. 2021 Dec 28. pii: S2211-1247(21)01671-5. [Epub ahead of print]37(13): 110171
      Macrophages are often prominently present in the tumor microenvironment, where distinct macrophage populations can differentially affect tumor progression. Although metabolism influences macrophage function, studies on the metabolic characteristics of ex vivo tumor-associated macrophage (TAM) subsets are rather limited. Using transcriptomic and metabolic analyses, we now reveal that pro-inflammatory major histocompatibility complex (MHC)-IIhi TAMs display a hampered tricarboxylic acid (TCA) cycle, while reparative MHC-IIlo TAMs show higher oxidative and glycolytic metabolism. Although both TAM subsets rapidly exchange lactate in high-lactate conditions, only MHC-IIlo TAMs use lactate as an additional carbon source. Accordingly, lactate supports the oxidative metabolism in MHC-IIlo TAMs, while it decreases the metabolic activity of MHC-IIhi TAMs. Lactate subtly affects the transcriptome of MHC-IIlo TAMs, increases L-arginine metabolism, and enhances the T cell suppressive capacity of these TAMs. Overall, our data uncover the metabolic intricacies of distinct TAM subsets and identify lactate as a carbon source and metabolic and functional regulator of TAMs.
    Keywords:  TCA cycle break; immunometabolism; immunosuppression; lactate; macrophage metabolism; metabolomics; non-small-cell lung carcinoma; single-cell metabolic profiling; tumor microenvironment; tumor-associated macrophages
  11. Drug Resist Updat. 2021 Dec 16. pii: S1368-7646(21)00056-X. [Epub ahead of print] 100796
      Driver mutations promote initiation and progression of cancer. Pharmacological treatment can inhibit the action of the mutant protein; however, drug resistance almost invariably emerges. Multiple studies revealed that cancer drug resistance is based upon a plethora of distinct mechanisms. Drug resistance mutations can occur in the same protein or in different proteins; as well as in the same pathway or in parallel pathways, bypassing the intercepted signaling. The dilemma that the clinical oncologist is facing is that not all the genomic alterations as well as alterations in the tumor microenvironment that facilitate cancer cell proliferation are known, and neither are the alterations that are likely to promote metastasis. For example, the common KRasG12C driver mutation emerges in different cancers. Most occur in NSCLC, but some occur, albeit to a lower extent, in colorectal cancer and pancreatic ductal carcinoma. The responses to KRasG12C inhibitors are variable and fall into three categories, (i) new point mutations in KRas, or multiple copies of KRAS G12C which lead to higher expression level of the mutant protein; (ii) mutations in genes other than KRAS; (iii) original cancer transitioning to other cancer(s). Resistance to adagrasib, an experimental antitumor agent exerting its cytotoxic effect as a covalent inhibitor of the G12C KRas, indicated that half of the cases present multiple KRas mutations as well as allele amplification. Redundant or parallel pathways included MET amplification; emerging driver mutations in NRAS, BRAF, MAP2K1, and RET; gene fusion events in ALK, RET, BRAF, RAF1, and FGFR3; and loss-of-function mutations in NF1 and PTEN tumor suppressors. In the current review we discuss the molecular mechanisms underlying drug resistance while focusing on those emerging to common targeted cancer drivers. We also address questions of why cancers with a common driver mutation are unlikely to evolve a common drug resistance mechanism, and whether one can predict the likely mechanisms that the tumor cell may develop. These vastly important and tantalizing questions in drug discovery, and broadly in precision medicine, are the focus of our present review. We end with our perspective, which calls for target combinations to be selected and prioritized with the help of the emerging massive compute power which enables artificial intelligence, and the increased gathering of data to overcome its insatiable needs.
    Keywords:  Cancer; Chemotherapy; Chromatin accessibility; Drug discovery; Drug resistance; Epigenetics; Interactome; MAPK; Precision medicine; Single cell; Transcriptomics
  12. Clin Cancer Res. 2021 Dec 29. pii: clincanres.1442.2021. [Epub ahead of print]
      PURPOSE: Extensive work in pre-clinical models has shown that microenvironmental cells influence many aspects of cancer cell behavior, including metastatic potential and their sensitivity to therapeutics. In the human setting, this behavior is mainly correlated with the presence of immune cells. Here, in addition to T cells, B cells, macrophages and mast cells, we identified the relevance of non-immune cell types for breast cancer survival and therapy benefit, including fibroblasts, myoepithelial cells, muscle cells, endothelial cells, and 7 distinct epithelial cell types.DESIGN: Using single-cell sequencing data, we generated reference profiles for all these cell types. We used these reference profiles in deconvolution algorithms to optimally detangle the cellular composition of over 3,500 primary breast tumors of patients that were enrolled in the SCAN-B and MATADOR clinical trials, and for which bulk mRNA sequencing data were available.
    RESULTS: This large data set enables us to identify and subsequently validate the cellular composition of microenvironments that distinguish differential survival and treatment benefit for different treatment regimens in primary breast cancer patients. In addition to immune cells, we have identified that survival and therapy benefit are characterized by various contributions of distinct epithelial cell types.
    CONCLUSIONS: From our study, we conclude that differential survival and therapy benefit of breast cancer patients are characterized by distinct microenvironments that include specific populations of immune and epithelial cells.
  13. Cancer Res. 2021 Dec 29. pii: canres.1446.2021. [Epub ahead of print]
      Aberrant activation of nuclear factor-κB (NF-κB) orchestrates a critical role in tumor carcinogenesis; however, the regulatory mechanisms underlying this activation are not fully understood. Here we report that a novel lncRNA Uc003xsl.1 is highly expressed in triple-negative breast cancer (TNBC) and correlates with poor outcomes in TNBC patients. Uc003xsl.1 directly bound nuclear transcriptional factor NF-κB-repressing factor (NKRF), subsequently preventing NKRF from binding to a specific negative regulatory element in the promoter of the NF-κB responsive gene IL8 and abolishing the negative regulation of NKRF on NF-κB-mediated transcription of IL8. Activation of the NF-κB/IL8 axis promoted the progression of TNBC. Trop2-based antibody-drug conjugates have been applied in clinical trials in TNBC. In this study, a Trop2-targeting, redox-responsive nanoparticle was developed to systematically deliver Uc003xsl.1 siRNA to TNBC cells in vivo, which reduced Uc003xsl.1 expression and suppressed TNBC tumor growth and metastasis. Therefore, targeting Uc003xsl.1 to suppress the NF-κB/IL8 axis represents a promising therapeutic strategy for TNBC treatment.
  14. Cell. 2021 Dec 22. pii: S0092-8674(21)01426-4. [Epub ahead of print]
    Immunoprofiler Consortium
      Cancers display significant heterogeneity with respect to tissue of origin, driver mutations, and other features of the surrounding tissue. It is likely that individual tumors engage common patterns of the immune system-here "archetypes"-creating prototypical non-destructive tumor immune microenvironments (TMEs) and modulating tumor-targeting. To discover the dominant immune system archetypes, the University of California, San Francisco (UCSF) Immunoprofiler Initiative (IPI) processed 364 individual tumors across 12 cancer types using standardized protocols. Computational clustering of flow cytometry and transcriptomic data obtained from cell sub-compartments uncovered dominant patterns of immune composition across cancers. These archetypes were profound insofar as they also differentiated tumors based upon unique immune and tumor gene-expression patterns. They also partitioned well-established classifications of tumor biology. The IPI resource provides a template for understanding cancer immunity as a collection of dominant patterns of immune organization and provides a rational path forward to learn how to modulate these to improve therapy.
    Keywords:  Pan Cancer analysis; immune profiling; solid tumor microenvironement; system immunology; tumor immunology; unsupervised clustering
  15. Neuro Oncol. 2021 Dec 29. pii: noab302. [Epub ahead of print]
      BACKGROUND: Glioblastomas are highly resistant to therapy, and virtually all patients experience tumor recurrence after standard-of-care treatment. Surgical tumor resection is a cornerstone in glioblastoma therapy, but its impact on cellular phenotypes in the local post-surgical microenvironment has yet to be fully elucidated.METHODS: We developed a preclinical orthotopic xenograft tumor resection model in rats with integrated 18F-FET PET/CT imaging. Primary and recurrent tumors were subject to bulk and single cell RNA sequencing. Differentially expressed genes and pathways were investigated and validated using tissue specimens from the xenograft model, 23 patients with matched primary/recurrent tumors, and a cohort including 190 glioblastoma patients. Functional investigations were performed in vitro with multiple patient-derived cell cultures.
    RESULTS: Tumor resection induced microglia/macrophage infiltration, angiogenesis as well as proliferation and upregulation of several stem cell related genes in recurrent tumor cells. Expression changes of selected genes SOX2, POU3F2, OLIG2 and NOTCH1 were validated at the protein level in xenografts and early recurrent patient tumors. Single cell transcriptomics revealed presence of distinct phenotypic cell clusters in recurrent tumors which deviated from clusters found in primary tumors. Recurrent tumors expressed elevated levels of pleiotrophin (PTN), secreted by both tumor cells and tumor-associated microglia/macrophages. Mechanistically, PTN could induce tumor cell proliferation, self-renewal and the stem cell program. In glioblastoma patients, high PTN expression was associated with poor overall survival, and identified as an independent prognostic factor.
    CONCLUSION: Surgical tumor resection is an iatrogenic driver of PTN-mediated self-renewal in glioblastoma tumor cells that promotes therapeutic resistance and tumor recurrence.
    Keywords:  Glioblastoma; Pleiotrophin; Recurrence; Self-renewal; Tumor resection
  16. Nat Cancer. 2021 Apr;2(4): 400-413
      The addition of HER2-targeted agents to neoadjuvant chemotherapy has dramatically improved pathological complete response (pCR) rates in early-stage, HER2-positive breast cancer. Nonetheless, up to 50% of patients have residual disease after treatment, while others are likely overtreated. Here, we performed multiplex spatial proteomic characterization of 122 samples from 57 HER2-positive breast tumors from the neoadjuvant TRIO-US B07 clinical trial sampled pre-treatment, after 14-21 d of HER2-targeted therapy and at surgery. We demonstrated that proteomic changes after a single cycle of HER2-targeted therapy aids the identification of tumors that ultimately undergo pCR, outperforming pre-treatment measures or transcriptomic changes. We further developed and validated a classifier that robustly predicted pCR using a single marker, CD45, measured on treatment, and showed that CD45-positive cell counts measured via conventional immunohistochemistry perform comparably. These results demonstrate robust biomarkers that can be used to enable the stratification of sensitive tumors early during neoadjuvant HER2-targeted therapy, with implications for tailoring subsequent therapy.
  17. Cell Rep. 2021 Dec 28. pii: S2211-1247(21)01681-8. [Epub ahead of print]37(13): 110181
      The EGFR/Erk pathway is triggered by extracellular ligand stimulation, leading to stimulus-dependent dynamics of pathway activity. Although mechanical properties of the microenvironment also affect Erk activity, their effects on Erk signaling dynamics are poorly understood. Here, we characterize how the stiffness of the underlying substratum affects Erk signaling dynamics in mammary epithelial cells. We find that soft microenvironments attenuate Erk signaling, both at steady state and in response to epidermal growth factor (EGF) stimulation. Optogenetic manipulation at multiple signaling nodes reveals that intracellular signal transmission is largely unaffected by substratum stiffness. Instead, we find that soft microenvironments decrease EGF receptor (EGFR) expression and alter the amount and spatial distribution of EGF binding at cell membranes. Our data demonstrate that the mechanical microenvironment tunes Erk signaling dynamics via receptor-ligand interactions, underscoring how multiple microenvironmental signals are jointly processed through a highly conserved pathway that regulates tissue development, homeostasis, and disease progression.
    Keywords:  MAP kinase; morphodynamics; receptor tyrosine kinase; signaling dynamics; tissue mechanics
  18. Cell. 2021 Dec 18. pii: S0092-8674(21)01427-6. [Epub ahead of print]
      Non-small cell lung cancers (NSCLCs) harboring KEAP1 mutations are often resistant to immunotherapy. Here, we show that KEAP1 targets EMSY for ubiquitin-mediated degradation to regulate homologous recombination repair (HRR) and anti-tumor immunity. Loss of KEAP1 in NSCLC induces stabilization of EMSY, producing a BRCAness phenotype, i.e., HRR defects and sensitivity to PARP inhibitors. Defective HRR contributes to a high tumor mutational burden that, in turn, is expected to prompt an innate immune response. Notably, EMSY accumulation suppresses the type I interferon response and impairs innate immune signaling, fostering cancer immune evasion. Activation of the type I interferon response in the tumor microenvironment using a STING agonist results in the engagement of innate and adaptive immune signaling and impairs the growth of KEAP1-mutant tumors. Our results suggest that targeting PARP and STING pathways, individually or in combination, represents a therapeutic strategy in NSCLC patients harboring alterations in KEAP1.
    Keywords:  BRCAness; EMSY; KEAP1; NSCLC; PARP inhibitors; STING agonsts; immune evasion; interferon; lung cancer; ubiquitination
  19. J Biol Chem. 2021 Dec 22. pii: S0021-9258(21)01334-X. [Epub ahead of print] 101524
      RNA binding protein RBM28 (RBM28), as a nucleolar component of spliceosomal small nuclear ribonucleoproteins (snRNPs), is involved in the nucleolar stress response. Whether and how RBM28 regulates tumor progression remain unclear. Here, we report that RBM28 is frequently overexpressed in various types of cancer and that its upregulation is associated with a poor prognosis. Functional and mechanistic assays revealed that RBM28 promotes the survival and growth of cancer cells by interacting with the DNA binding domain of tumor suppressor p53 to inhibit p53 transcriptional activity. Upon treatment with chemotherapeutic drugs (e.g., adriamycin), RBM28 is translocated from the nucleolus to the nucleoplasm, which is likely mediated via phosphorylation of RBM28 at Ser122 by DNA checkpoint kinases 1 and 2 (Chk1/2), indicating that RBM28 may act as a nucleolar stress sensor in response to DNA damage stress. Our findings not only reveal RBM28 as a potential biomarker and therapeutic target for cancers, but also provide mechanistic insights into how cancer cells convert stress signals into a cellular response linking the nucleolus to regulation of the tumor suppressor p53.
    Keywords:  Chk1; Chk2; RBM28; nucleolar stress; p53; phosphorylation
  20. Mol Cell. 2021 Dec 20. pii: S1097-2765(21)01038-8. [Epub ahead of print]
      Ferroptosis is a unique type of non-apoptotic cell death resulting from the unrestrained occurrence of peroxidized phospholipids, which are subject to iron-mediated production of lethal oxygen radicals. This cell death modality has been detected across many organisms, including in mammals, where it can be used as a defense mechanism against pathogens or even harnessed by T cells to sensitize tumor cells toward effective killing. Conversely, ferroptosis is considered one of the main cell death mechanisms promoting degenerative diseases. Emerging evidence suggests that ferroptosis represents a vulnerability in certain cancers. Here, we critically review recent advances linking ferroptosis vulnerabilities of dedifferentiating and persister cancer cells to the dependency of these cells on iron, a potential Achilles heel for small-molecule intervention. We provide a perspective on the mechanisms reliant on iron that contribute to the persister cancer cell state and how this dependency may be exploited for therapeutic benefits.
  21. Cancer Cell. 2021 Dec 16. pii: S1535-6108(21)00660-7. [Epub ahead of print]
      In a recent publication in Nature, Zhang et al. report that foreign antigen stimulation elicits bountiful changes in lymphatic metabolite production-changes that include B cells secreting GABA, which reprograms macrophages and limits T cell cytotoxicity. This signifies a new mechanism by which B cells regulate immune suppression and facilitate tumor progression.
  22. Proc Natl Acad Sci U S A. 2022 Jan 04. pii: e2112491119. [Epub ahead of print]119(1):
      Brain metastases are a leading cause of death in patients with breast cancer. The lack of clinical trials and the presence of the blood-brain barrier limit therapeutic options. Furthermore, overexpression of the human epidermal growth factor receptor 2 (HER2) increases the incidence of breast cancer brain metastases (BCBM). HER2-targeting agents, such as the monoclonal antibodies trastuzumab and pertuzumab, improved outcomes in patients with breast cancer and extracranial metastases. However, continued BCBM progression in breast cancer patients highlighted the need for novel and effective targeted therapies against intracranial metastases. In this study, we engineered the highly migratory and brain tumor tropic human neural stem cells (NSCs) LM008 to continuously secrete high amounts of functional, stable, full-length antibodies against HER2 (anti-HER2Ab) without compromising the stemness of LM008 cells. The secreted anti-HER2Ab impaired tumor cell proliferation in vitro in HER2+ BCBM cells by inhibiting the PI3K-Akt signaling pathway and resulted in a significant benefit when injected in intracranial xenograft models. In addition, dual HER2 blockade using anti-HER2Ab LM008 NSCs and the tyrosine kinase inhibitor tucatinib significantly improved the survival of mice in a clinically relevant model of multiple HER2+ BCBM. These findings provide compelling evidence for the use of HER2Ab-secreting LM008 NSCs in combination with tucatinib as a promising therapeutic regimen for patients with HER2+ BCBM.
    Keywords:  HER2; brain metastasis; neural stem cells; tucatinib