Chronic AMPK inactivation slows SHH medulloblastoma progression by inhibiting mTORC1 signaling and depleting tumor stem cell populations

We show that inactivating AMPK in vivo in a genetic model of medulloblastoma depletes tumor stem cell populations and slows tumor progression. Medulloblastoma, the most common malignant pediatric brain tumor, grows as heterogenous communities comprising diverse types of tumor and stromal cells. We have previously shown that different types of cells in medulloblastomas show different sensitivities to specific targeted therapies. To determine if specific populations depend on AMPK, we analyzed mice with AMPK-inactivated medulloblastomas. We engineered mice with brain-wide, conditional deletion of the AMPK catalytic subunits Prkaa1 and Prkaa2 and conditional expression SmoM2, an oncogenic Smo allele that hyperactivates Sonic Hedgehog (SHH) signaling. We compared the medulloblastomas that formed in these mice to tumors that form in AMPK-intact mice with conditional SmoM2 expression. AMPK-inactivated tumors progressed more slowly, allowing longer event-free survival. AMPK inactivation altered the cellular heterogeneity, determined by scRNA-seq, increasing differentiation, decreasing tumor stem cell populations and reducing glio-neuronal multipotency. Mechanistically, AMPK inactivation altered glycolytic gene expression and decreased mTORC1 pathway activation. Hk2-deletion reproduced key aspects of the AMPK-inactivation phenotype, implicating altered glycolysis in the tumor suppressive effect of AMPK inactivation. Our results show that AMPK inactivation impairs tumor growth through mechanisms that disproportionately affect tumor stem cell populations. As stem cells are intrinsically resistant to current cytotoxic therapy that drives recurrence, finding ways to target these populations may prevent treatment failure. Our data suggest that targeted AMPK inactivation may produce therapeutic effects in tumor stem cell populations refractory to other therapeutic approaches.

TB-3 miR-33a depletion accelerate medulloblastoma generation and invasion

Background and purposes: Lipid metabolism have been shown to be associated with tumorigenicity in various malignancies. The purpose of this study was to investigate the association of miR-33, a key regulator of lipid metabolism, in tumorigenicity and progression of medulloblastoma. Methods: Incidence of medulloblastoma and histopathological findings were compared between ptch1+/- mice and ptch1+/- miR-33a-/- mice. Tumors extracted from these mice were transplanted subcutaneously in nude mice (n=14 for ptch1+/-, n=19 for ptch1+/- miR-33a-/-) and in C57BL/6 mice (n=12 for each). Gene expression profile was compared between tumors from ptch1+/- mice and those from ptch1+/- miR-33a-/- mice. Results: Knockout of miR-33a in ptch1+/- transgenic mouse model increased the incidence of spontaneous generation of medulloblastoma from 34.5% to 84.0% (p< 0.001) at 12 months. Histopathological analysis showed infiltrative tumor borders in ptch1+/- miR-33a-/- tumors as compared with ptch1+/- ones. Tumor formation was observed in 21.4% for ptch1+/- tumors and 68.4% for ptch1+/- miR-33a-/- tumors in nude mice (p= 0.008). It was observed in 0% and 16.7% in immune competent mice. RNA sequencing detected that SCD1 and SREBF1 was upregulated in tumors from miR-33a knockout mice. Discussion: Our results demonstrated that depletion of miR-33a accelerated medulloblastoma generation and invasion. miR-33a may also be important for immune evasion. SCD1, which is reported to play a role in tumor stem cell maintenance and metastasis, can be a potential therapeutic target for medulloblastoma.

A Pan-Cancer Analysis of the KIF Family Gene and their Association with Prognosis, Tumor Microenvironment, and Therapeutic Targets

Background: Recently, studies have shown that kinesins(KIF) play an important role in the occurrence and development of many tumors. However, there is no complete understanding of the role of KIF family in Pan cancer, and its role in the immunity and tumor microenvironment (TME) is unclear.Methods: Based on TCGA database and integrated several R packages, we explored the relationship between the expression of KIF genes and patient survival, immune subtypes, TME, tumor stem cell correlation, and drug sensitivity in cancer.Results: We use nine highly expressed KIF genes(KIF2C, KIF4A, KIF7, KIF11, KIF14, KIF18A, KIF18B, KIF20A, KIF20B) to represent whole KIF family. The change in KIF gene expression was significantly related to overall survival. The nine KIFs' high expression is accompanied by the up-regulation of C1 immune subtype, which is related to cell proliferation and interruption of immune process. Further, KIF gene expression showed significant correlation and cancer cell stemness characteristics. Top25 relevant KIF-drug pairs were displayed according to their P values. We further discussed KIF family influence in Mesothelioma(MESO) and Sarcoma(SARC). The CIBERSORT results manifested that increased level of infiltration of B cells naive, Mast cells resting and NK cells activated could be used as a protective factor to promote survival.Conclusions: Our study supplemented a complete map of the effect of KIF family in Pan cancer. We suggested that KIF family may be a potential target for cancer therapy.

microRNA-26a represses pancreatic cancer cell malignant behaviors by targeting E2F7

Dysregulation of microRNAs (miRNAs) exerts key roles in the development of pancreatic cancer (PCa). miR-26a is reportedly a tumor suppressor in cancers. However, whether miR-26a modulates PCa progression is poorly understood. Here, we found that miR-26a was down-regulated in PCa. Overexpressed miR-26a suppressed PCa cell proliferation, colony formation, and tumor stem cell properties. Mechanically, the transcription factor E2F7 is a downstream target of miR-26a. miR-26a decreased E2F7 expression through binding to the 3’-untranslated region (UTR) of E2F7. Decreased miR-26a in PCa tissues was inversely correlated with E2F7. The inhibitory effects of miR-26a in PCa were reversed by E2F7 overexpression. Consistently, the knockout of E2F7 further significantly inhibited the growth of PCa cells combined with miR-26a overexpression. Further study revealed that E2F7 bound the promoter of vascular endothelial growth factor A (VEGFA), a key factor in angiogenesis, and transcriptionally activated the expression of VEGFA. miR-26a overexpression attenuated the effects of E2F7 on VEGFA promotion. Our results uncovered the novel function of miR-26a/E2F7/VEGFA in PCa, making miR-26a a possible target for PCa treatment.

Effect of the Neddylation Inhibitor Pevonedistat on Normal Hematopoietic Stem Cell Subsets and Immune Cell Composition

Introduction: Antitumor activity of the neddylation inhibitor pevonedistat has been documented in several hematologic and non-hematologic malignancies. Unexpectedly, Zhou et al (PNAS, 2016) discovered a dose-dependent biphasic effect of pevonedistat in solid tumor cell lines. While micromolar concentrations inhibited tumor cell growth, low nanomolar concentrations significantly increased cell proliferation and tumor stem cell self-renewal both in vitro and in vivo. The effect of low-dose pevonedistat has not yet been explored in the field of hematopoietic stem cell transplantation. Therefore, we evaluated how pevonedistat affects the viabiilty, growth and proportions of CD34 + cell subpopulations. In view of the emerging role of neddylation in the regulation of both innate and adaptive immunity, we also investigated the influence of pevonedistat on T-cell activation to explore a potentially beneficial effect on posttransplant immune complications. Methods and Results: Using the WST-1 assay we confirmed the biphasic effect of pevonedistat on normal mobilized CD34 + cells. Incubation for 72 h with 0.1 µM pevonedistat significantly increased metabolic activity as a surrogate parameter for proliferation, while 1.0 µM pevonedistat showed a cytotoxic effect. We explored the underlying mechanism for the low-dose effect. Since Zhou et al. previously showed that pevonedistat can promote tumor stem cell proliferation by inducing EGFR homodimerization, we used a proximity ligation assay and found that 0.1 µM pevonedistat induced EGFR homodimerization in normal mobilized CD34 + cells, too. In addition to homodimerization, we also looked at phosphorylation at Tyr1068, a marker of EGFR activation. By flow cytometry, we showed that phosphorylation was increased by 0.01 µM and 0.1 µM pevonedistat. Using an ELISA-based transcription assay, we also observed a biphasic effect of pevonedistat on c-Myc expression, which is regarded as a marker of 'stemness'. Incubation with pevonedistat for 72 hrs at 0.01 and 0.1 µM stimulated expression of c-Myc, whereas incubation at 1.0 µM downregulated c-Myc. Fractions of hematopoietic stem and progenitor cell (HSPC) subpopulations were measured in CD34 + cells from cord blood after incubation with 0.01, 0.1 and 1.0 µM pevonedistat. Flow cytometry was performed using antibodies against CD34, CD45RA and CD133, as well as 7-AAD for testing cell viability. Exposure to pevonedistat for 72 hrs at 0.1 µM caused an increase in the number of CD34 + cells compared to vehicle-treated CD34+ cells at 72 h as well as compared to initial number of CD34+ cells, whereas 1.0 µM caused a significant decrease. The absolute number of multipotent progenitors (MPP) (CD34 +CD133 +CD45RA -) remained relatively stable at all concentrations, while lympho-myeloid progenitors (LMPP) (CD34+CD133+CD45RA+) and late progenitors (LP) (CD34+CD133-CD45RA+) increased slightly with 0.1 µM pevonedistat compared with controls. However, a significant decrease in LMPP and LP cell numbers was observed at 1.0 µM. Different concentrations of pevonedistat were tested for their capability to modulate allogeneically stimulated T cell activation in a multi-donor mixed lymphocyte reaction (mdMLR) assay in vitro. Mesenchymal stromal cells (MSCs)-derived extracellular vesicles (MSC-EV) were used as internal immuno-modulatory and non-immuno-modulatory controls in the assay. After 5 days, alterations in the immune cell composition were analyzed by flow cytometry. Pevonedistat was not toxic for MNCs in the mdMLR. However, it decreased the number of activated (CD25high CD54+) CD4+ cells and CD8+ cells. Conclusions: One of the problems in the post-transplant period is a rapid decline in MPP numbers, associated with increased risk of engraftment failure. We showed that low-dose pevonedistat (0.1 µM) is capable of increasing the number of CD34 + cells in vitro while keeping the absolute number of MPPs stable. This finding, together with the observed increase in c-Myc expression, suggests that pevonedistat may help to preserve 'stemness' of CD34+ donor cells, thus supporting engraftment of hematopoietic stem and progenitor cells. Furthermore, the immunosuppressive effects revealed by mdMLR suggest that low-dose pevonedistat may also play a useful immunomodulatory role in the post-transplant setting to potentially reduce the risk of graft-versus-host disease. Figure 1 Figure 1. Disclosures Majidi: Takeda: Research Funding. Germing: Jazz Pharmaceuticals: Honoraria; Bristol-Myers Squibb: Honoraria, Other: advisory activity, Research Funding; Celgene: Honoraria; Novartis: Honoraria, Research Funding; Janssen: Honoraria. Zeiser: Incyte, Mallinckrodt, Novartis: Honoraria, Speakers Bureau. Gattermann: Celgene: Honoraria; Takeda: Research Funding; Novartis: Honoraria.

Cell Differentiation Trajectory-Associated Molecular Classification of Osteosarcoma

This study aims to investigate the differentiation trajectory of osteosarcoma cells and to construct molecular subtypes with their respective characteristics and generate a multi-gene signature for predicting prognosis. Integrated single-cell RNA-sequencing (scRNA-seq) data, bulk RNA-seq data and microarray data from osteosarcoma samples were used for analysis. Via scRNA-seq data, time-related as well as differentiation-related genes were recognized as osteosarcoma tumor stem cell-related genes (OSCGs). In Gene Expression Omnibus (GEO) cohort, osteosarcoma patients were classified into two subtypes based on prognostic OSCGs and it was found that molecular typing successfully predicted overall survival, tumor microenvironment and immune infiltration status. Further, available drugs for influencing osteosarcoma via prognostic OSCGs were revealed. A 3-OSCG-based prognostic risk score signature was generated and by combining other clinic-pathological independent prognostic factor, stage at diagnosis, a nomogram was established to predict individual survival probability. In external independent TARGET cohort, the molecular types, the 3-gene signature as well as nomogram were validated. In conclusion, osteosarcoma cell differentiation occupies a crucial position in many facets, such as tumor prognosis and microenvironment, suggesting promising therapeutic targets for this disease.

A Preclinical Pipeline for Translational Precision Medicine—Experiences from a Transdisciplinary Brain Tumor Stem Cell Project

Efficient transdisciplinary cooperation promotes the rapid discovery and clinical application of new technologies, especially in the competitive sector of oncology. In this review, written from a clinical-scientist point of view, we used glioblastoma—the most common and most aggressive primary brain tumor as a model disease with a largely unmet clinical need, despite decades of intensive research—to promote transdisciplinary medicine. Glioblastoma stem-like cells (GSCs), a special tumoral cell population analogue to healthy stem cells, are considered largely responsible for the progression of the disease and the mediation of therapy resistance. The presented work followed the concept of translational science, which generates the theoretical backbones of translational research projects, and aimed to close the preclinical gap between basic research and clinical application. Thus, this generated an integrated translational precision medicine pipeline model based on recent theoretical and experimental publications, which supports the accelerated discovery and development of new paths in the treatment of GSCs. The work may be of interest to the general field of precision medicine beyond the field of neuro-oncology such as in Cancer Neuroscience.

HCG18 Participates in Vascular Invasion of Hepatocellular Carcinoma by Regulating Macrophages and Tumor Stem Cells

ObjectivesTo identify key genes involved in vascular invasion in hepatocellular carcinoma (HCC), to describe their regulatory mechanisms, and to explore the immune microenvironment of HCC.MethodologyIn this study, the genome, transcriptome, and immune microenvironment of HCC were assessed by using multi-platform data from The Cancer Genome Atlas (n = 373) and GEO data (GSE149614). The key regulatory networks, transcription factors and core genes related to vascular invasion and prognosis were explored based on the CE mechanism. Survival analysis and gene set enrichment were used to explore pathways related to vascular invasion. Combined with single-cell transcriptome data, the distribution of core gene expression in various cells was observed. Cellular communication analysis was used to identify key cells associated with vascular invasion. Pseudo-temporal locus analysis was used to explore the regulation of core genes in key cell phenotypes. The influence of core genes on current immune checkpoint therapy was evaluated and correlations with tumor stem cell scores were explored.ResultsWe obtained a network containing 1,249 pairs of CE regulatory relationships, including 579 differential proteins, 28 non-coding RNAs, and 37 miRNAs. Three key transcription factors, ILF2, YBX1, and HMGA1, were identified, all regulated by HCG18 lncRNA. ScRNAseq showed that HCG18 co-localized with macrophages and stem cells. CIBERSORTx assessed 22 types of immune cells in HCC and found that HCG18 was positively correlated with M0 macrophages, while being negatively correlated with M1 and M2 macrophages, monocytes, and dendritic cells. Cluster analysis based on patient prognosis suggested that regulating phenotypic transformation of macrophages could be an effective intervention for treating HCC. At the same time, higher expression of HCG18, HMGA1, ILF2, and YBX1 was associated with a higher stem cell score and less tumor differentiation. Pan cancer analysis indicated that high expression of HCG18 implies high sensitivity to immune checkpoint therapy.ConclusionHCG18 participates in vascular invasion of HCC by regulating macrophages and tumor stem cells through three key transcription factors, YBX1, ILF2, and HMGA1.

MSX2 represses tumor stem cell phenotypes within oral squamous cell carcinomas via SOX2 degradation

Oral squamous cell carcinoma (OSCC) is the sixth malignancy in the world with high incidence. The MSX2 (muscle segment homeobox 2)–Sry-related high-mobility box 2 (SOX2) signaling pathway plays a significant role in maintaining cancer stem cells, which are the origin of malignancy, leading to unfavorable outcomes in several carcinomas. This study aims to elucidate the mechanisms through which the MSX2–SOX2 pathway controls the cancer stem cell-like characterization in OSCC. The results showed that MSX2 was remarkably downregulated in OSCC and that the MSX2 expression level was related to unfavorable outcomes in patients with OSCC. Meanwhile, the MSX2 expression level was lower in the CD44+/CD24− population than in the other populations of OSCC cells. The OSCC2 cells exhibited decreased percentage of CD44+/CD24− cells, owing to MSX2 overexpression but increased owing to MSX2 knockdown. Moreover, a negative correlation was observed between MSX2 expression and is SOX2 transcriptional levels in different populations within the OSCC cell lines. Regarding the loss and gain of function, cancer stem cell phenotypes such as tumor globular formation, CD44+ subpopulation cells, and stem cell-associated gene expression were enhanced by MSX2 knockdown in OSCC CD44+/CD24− cells but decreased by MSX2 overexpression in other OSCC populations. However, these events were counteracted by the co-knockdown or SOX2 overexpression. Cells with MSX2 overexpression or knockdown formed smaller or bigger cancers in vivo, thereby showing a lower or a higher tumor incidence, respectively. Thus, our results confirm that MSX2 has a tumor suppression effect on the cancer stem cell phenotypes of OSCC and indicate that the MSX2–SOX2 signaling pathway could be a useful target for OSCC treatment.