Tumor-initiating Stem Cell-like Cells Research Articles

Abstract 2457: NANOG bindsPRC2 to reprogram metabolismandpromotelabel-retaining populationin experimental mouse and clinical carcinoma

Abstract Background: Alcohol and HCV synergistically promote hepatocarcinogenesis. Our previous studies indicated that this synergistic effect of HCV and alcohol was mediated by TLR4, which increases the expression of NANOG, a transcription factor important for the stemness of TICs. Our recent studies further indicated that NANOG could repress mitochondrial oxidative phosphorylation (OXPHOS) genes to support the self-renewal and drug resistance of tumor-initiating stem cell-like cells (TICs), leading to relapse and metastasis (Chen et al., Cell Metabolism). In addition, approximately 39% of HCV-alcohol-associated HCCs have mutations in ARID1A, a component of the chromatin remodeling complex SWI/SNF. Hypothesis: The efficacy of the combined FAOi and PRC2 inhibition (PRC2i) therapy relies on activation of cell death signaling. Aims: We (1) tested if NANOG together with the PRC2 complex inhibits OXPHOS and generates TICs in the presence of ARID1A mutations; (2) tested if specific genetic alterations and NANOG cooperate to generate different classes of TICs for the development of HCC; (3) tested if ARID1A mutations with NANOG induction generate TICs. Methods: We transduced LPCs with a lentiviral vector that expresses mCherry and used the CRISPR/Cas9 system to target Arid1a or Ctnnb1. EZH2, SUZ12 and EED were silenced in patient-derived TICs (with or without ARID1A mutations). Surviving cells are subjected to the spheroid formation assay on ultra-low attachment plates for analysis of their self-renewal ability. Results: Mutant Arid1a HCCs with Nanog overexpression caused HCC metastasis to the lung. The humanized FRG mice subjected to alcohol feeding and/or HCV infection developed HCCs, especially in the CTNNB1 or ARID1A mutant hepatoblast groups, six months post-HCV infection and/or alcohol feeding. HCV-infected humanized livers in these mice contained HCV RNA, but not in the UV-irradiated HCV infected group. Conclusion: ARID1A gene loss promotes sorafenib-resistance phenotype and self-renewal through PRC2 complex genes. We demonstrated that sorafenib induced cytochrome c release from mitochondria to cause apoptosis of TICs, that restoration of OXPHOS was overexpressed in TICs. The studies established a novel therapy to overcome the chemoresistance of TICs for HCC treatment. Citation Format: Da-Wei Yeh, Juan Carlos Hernandez, Keigo Machida. NANOG bindsPRC2 to reprogram metabolismandpromotelabel-retaining populationin experimental mouse and clinical carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2457.

Fate and functional roles of Prominin 1+ cells in liver injury and cancer

Prominin 1 (PROM1) is one of a few clinically relevant progenitor markers in human alcoholic hepatitis (AH) and hepatocellular carcinoma (HCC), and mouse liver tumor initiating stem cell-like cells (TICs). However, the origin, fate and functions of PROM1+ cells in AH and HCC are unknown. Here we show by genetic lineage tracing that PROM1+ cells are derived in part from hepatocytes in AH and become tumor cells in mice with diethyl nitrosamine (DEN)-initiated, Western alcohol diet-promoted liver tumorigenesis. Our RNA sequencing analysis of mouse PROM1+ cells, reveals transcriptomic landscapes indicative of their identities as ductular reaction progenitors (DRPs) and TICs. Indeed, single-cell RNA sequencing reveals two subpopulations of Prom1+ Afp– DRPs and Prom1+ Afp+ TICs in the DEN-WAD model. Integrated bioinformatic analysis identifies Discodin Domain Receptor 1 (DDR1) as a uniquely upregulated and patient-relevant gene in PROM1+ cells in AH and HCC. Translational relevance of DDR1 is supported by its marked elevation in HCC which is inversely associated with patient survival. Further, knockdown of Ddr1 suppresses the growth of TICs and TIC-derived tumor growth in mice. These results suggest the importance of PROM1+ cells in the evolution of liver cancer and DDR1 as a potential driver of this process.

Baicalein Targets GTPase-Mediated Autophagy to Eliminate Liver Tumor-Initiating Stem Cell-Like Cells Resistant to mTORC1 Inhibition.

Drug resistance is a major problem in the treatment of liver cancer. Mammalian Target of Rapamycin 1 (mTORC1) inhibitors have been tested for the treatment of liver cancer based on hyperactive mTOR in this malignancy. However, their clinical trials showed poor outcome, most likely due to their ability to upregulate CD133 and promote chemoresistance. The CD133+ tumor-initiating stem cell-like cells (TICs) isolated from mouse and human liver tumors are chemoresistant, and identification of an approach to abrogate this resistance is desired. In search of a compound that rescinds resistance of TICs to mTORC1 inhibition and improves chemotherapy, we identified baicalein (BC), which selectively chemosensitizes TICs and the human hepatocellular carcinoma (HCC) cell line Huh7 cells but not mouse and human primary hepatocytes. Nanobead pull-down and mass-spectrometric analysis, biochemical binding assay, and three-dimensional computational modeling studies reveal BC's ability to competitively inhibit guanosine triphosphate binding of SAR1B guanosine triphosphatase, which is essential for autophagy. Indeed, BC suppresses autophagy induced by an mTORC1 inhibitor and synergizes cell death caused by mTORC1 inhibition in TIC and Huh7 spheroid formation and in the patient-derived xenograft model of HCC. The BC-induced chemosensitization is rescued by SAR1B expression and phenocopied by SAR1B knockdown in cancer cells treated with a mTORC1 inhibitor. Conclusion: These results identify SAR1B as a target in liver TICs and HCC cells resistant to mTORC1 inhibition.

NANOG-Dependent Metabolic Reprogramming and Symmetric Division in Tumor-Initiating Stem-like Cells.

Alcohol abuse synergistically heightens the development of the third most deadliest cancer hepatocellular carcinoma (HCC) in patients infected with hepatitis C virus (HCV). Ectopically expressed TLR4 promotes liver tumorigenesis in alcohol-fed HCV Ns5a or Core transgenic mice. CD133+/CD49f+tumor-initiating stem cell-like cells (TICs) isolated from these models are tumorigenic have p53 degradation via phosphorylation of the protective protein NUMB and its dissociation from p53 by the oncoprotein TBC1D15. Nutrient deprivation reduces overexpressed TBC1D15 in TICs via autophagy-mediated degradation, suggesting a possible role of this oncoprotein in linking metabolic reprogramming and self-renewal.

CBIO-23. CHARACTERIZATION OF BMP SYSTEM MUTATIONS IN RECURRENT PRIMARY GLIOBLASTOMA PRIMARY CELL CULTURES IN RELATION TO GLIOBLASTOMA INITIATING STEM-LIKE CELLS AND TEMOZOLOMIDE RESISTANCE

Glioblastoma multiforme (GBM) is the most prevalent and aggressive primary brain tumor. Its recurrence and rapidly acquired resistance to current therapies, including treatment with temozolomide (TMZ), results from the rapid expansion of re-emerging Glioblastoma Tumor Initiating stem cell-like Cells (GTICs). Targeted Exome Sequencing (TES) revealed that in such recurrent human GBM missense mutations arise in genes of the Bone Morphogenetic Protein (BMP) system in addition to those of other molecular systems found in primary GBM. To determine in which subpopulation BMP system mutations accumulate, we subjected two GBM primary cultures with a known mutations in ZFYVE16 (A290S) or BMPR1B (K222E) to targeted sequencing after FAC-sorting these cells based on the acknowledged stem cell markers CD44 and CD133. We found that ZFYVE16 (A290S) and BMPR1B (K222E) mutations accumulate within the CD133+/CD44- GTICs. Treatment of the primary culture with the latter mutation, with BMP4 suggests that the response to BMP signals is markedly reduced. Cells from these cultured were also cultured again after FAC-sorting for CD133 and CD44. Surprisingly, after three passages all subpopulations acquired a variation in expression of these markers specific for each patient. This shows that a 2D culture is able to loose and acquire stem cell markers and might resemble the original heterogeneity of the parental tumor more closely than we originally expected. In a separate set of experiments, RNA-sequencing of a TMZ-resistant primary GBM culture (GS295), created during the course of this work, compared to the TMZ-sensitive GS295, shows that several genes of the BMP system (NOGGIN, BMP7, ID1 and GATA3) are differentially expressed. Our results suggest that BMP system mutations tend to accumulate in CD133+ GTICs, that BMP signaling is altered within GBM primary cultures and that several mutated genes of the BMP system may correlate with acquisition of TMZ resistance.

Abstract 4331: Novel Wnt-SCD-LRP5/6 pathway linking liver fibrosis to cancer

Abstract Activated hepatic stellate cells (HSCs) are primarily responsible for the genesis of liver fibrosis which promotes liver tumor development. Stearoyl-CoA desaturase (SCD) which synthesizes monounsaturated fatty acid (MUFA such as oleic acid or palmitoleic acid), is implicated in metabolic syndrome, tumorigenesis and stemness. Indeed, we demonstrate SCD upregulation in both HSCs and liver tumor cells in patients. Further, SCD correlates with the advancing grade of HCC and mortality in patients. However, its causality in tumorigenesis and mesenchyme-tumor crosstalk, and underlying mechanisms, are unknown. The present study aimed to determine whether and how SCD promotes and links liver fibrosis and cancer. In both HSCs and liver tumor-initiating stem cell-like cells (TIC), we reveal that the Wnt effector β-catenin is a potent co-activator for SREBP-1-dependent Scd transcription as demonstrated by promoter-reporter assay and re-ChIP analysis. We also discover β-catenin which drives SCD expression is in turn stabilized by SCD-derived MUFA. To identify molecular targets of MUFA mediating this SCD-β-catenin positive loop, we performed MUFA-nano-beads pull-down assay with TIC lysate, ESI-MS based identification of MUFA interacting proteins, computational docking analysis, co-IP and ribonucleoprotein-IP. These analyses reveal that MUFA is essential for LRP5/6 expression: MUFA interferes Transportin-1 and Ran-1 interaction, resulting in suppressed nuclear import of the mRNA binding protein HuR, HuR cytoplasmic accumulation, and increased HuR binding to and stabilization of Wnt co-receptor Lrp5/6 mRNA. As such, genetic or pharmacologic SCD inhibition reduces cytosolic HuR, LRP5/6 expression, β-catenin stabilization, HSC activation and TIC self-renewal and attenuates liver fibrosis and tumorigenesis in mice. Moreover, conditional genetic ablation of Scd2 in HSCs not only abrogates HSC-mediated promotion of TIC-derived tumorigenesis in a xenograft mouse model but also inhibits DEN-induced liver tumor development in Col1a1-Cre; Scd2flox/flox mice (tumor volume reduced to 21.5 + 7.9 vs. 360.9 + 193 mm3 in Scd2flox/flox mice; tumor multiplicity decreased to 18 + 5.4 vs. 45 + 8.4 in Scd2flox/flox mice, both p<0.05). Collectively, our findings support that a newly disclosed Wnt-SCD-LRP5/6 loop may serve as a novel therapeutic target for liver cancer and underlies a known crosstalk between liver mesenchyme and liver tumor development. Citation Format: Keane Lai, Soo-Mi Kweon, Feng Chi, Edward Hwang, Raymond Wu, Yasuaki Kabe, Ramachandran Murali, Lopa Mishra, James Ntambi, Hidekazu Tsukamoto. Novel Wnt-SCD-LRP5/6 pathway linking liver fibrosis to cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4331. doi:10.1158/1538-7445.AM2017-4331

Stearoyl-CoA Desaturase Promotes Liver Fibrosis and Tumor Development in Mice via a Wnt Positive-Signaling Loop by Stabilization of Low-Density Lipoprotein-Receptor-Related Proteins 5 and 6

Stearoyl-CoA desaturase (SCD) synthesizes monounsaturated fatty acids (MUFAs) and has been associated with the development of metabolic syndrome, tumorigenesis, and stem cell characteristics. We investigated whether and how SCD promotes liver fibrosis and tumor development in mice. Rodent primary hepatic stellate cells (HSCs), mouse liver tumor-initiating stem cell-like cells (TICs), and human hepatocellular carcinoma (HCC) cell lines were exposed to Wnt signaling inhibitors and changes in gene expression patterns were analyzed. We assessed the functions of SCD by pharmacologic and conditional genetic manipulation in mice with hepatotoxic or cholestatic induction of liver fibrosis, orthotopic transplants of TICs, or liver tumors induced by administration of diethyl nitrosamine. We performed bioinformatic analyses of SCD expression in HCC vs nontumor liver samples collected from patients, and correlated levels with HCC stage and patient mortality. We performed nano-bead pull-down assays, liquid chromatography-mass spectrometry, computational modeling, and ribonucleoprotein immunoprecipitation analyses to identify MUFA-interacting proteins. We examined the effects of SCD inhibition on Wnt signaling, including the expression and stability of low-density lipoprotein-receptor-related proteins 5 and 6 (LRP5 and LRP6), by immunoblot and quantitative polymerase chain reaction analyses. SCD was overexpressed in activated HSC and HCC cells from patients; levels of SCD messenger RNA (mRNA) correlated with HCC stage and patient survival time. In rodent HSCs and TICs, the Wnt effector β-catenin increased sterol regulatory element binding protein 1-dependent transcription of Scd, and β-catenin in return was stabilized by MUFAs generated by SCD. This loop required MUFA inhibition of binding of Ras-related nuclear protein 1 (Ran1) to transportin 1 and reduced nuclear import of elav-like protein 1 (HuR), increasing cytosolic levels of HuR and HuR-mediated stabilization of mRNAs encoding LRP5 and LRP6. Genetic disruption of Scd and pharmacologic inhibitors of SCD reduced HSC activation and TIC self-renewal and attenuated liver fibrosis and tumorigenesis in mice. Conditional disruption of Scd2 in activated HSCs prevented growth of tumors from TICs and reduced the formation of diethyl nitrosamine-induced liver tumors in mice. In rodent HSCs and TICs, we found SCD expression to be regulated by Wnt-β-catenin signaling, and MUFAs produced by SCD provided a forward loop to amplify Wnt signaling via stabilization of Lrp5 and Lrp6 mRNAs, contributing to liver fibrosis and tumor growth. SCD expressed by HSCs promoted liver tumor development in mice. Components of the identified loop linking HSCs and TICs might be therapeutic targets for liver fibrosis and tumors.

TLR4-dependent tumor-initiating stem cell-like cells (TICs) in alcohol-associated hepatocellular carcinogenesis.

Alcohol abuse predisposes individuals to the development of hepatocellular carcinoma (HCC) and synergistically heightens the HCC risk in patients infected with hepatitis C virus (HCV). The mechanisms of this synergism have been elusive until our recent demonstration of the obligatory role of ectopically expressed TLR4 in liver tumorigenesis in alcohol-fed HCV Ns5a or Core transgenic mice. CD133+/CD49f+ tumor-initiating stem cell-like cells (TICs) isolated from these models are tumorigenic in a manner dependent on TLR4 and NANOG. TICs' tumor-initiating activity and chemoresistance are causally associated with inhibition of TGF-β tumor suppressor pathway due to NANOG-mediated expression of IGF2BP3 and YAP1. TLR4/NANOG activation causes p53 degradation via phosphorylation of the protective protein NUMB and its dissociation from p53 by the oncoprotein TBC1D15. Nutrient deprivation reduces overexpressed TBC1D15 in TICs via autophagy-mediated degradation, suggesting a possible role of this oncoprotein in linking metabolic reprogramming and self-renewal.

Alcohol, TLR4-TGF-β antagonism, and liver cancer.

Alcohol abuse and obesity are two known risk factors for hepatocellular carcinoma (HCC) that also synergistically promote HBV/HCV-related carcinogenesis. TLR4, the receptor for endotoxin, participates in inflammatory processes such as M1 activation of hepatic macrophages in alcoholic liver disease. However, its role in liver carcinogenesis via ectopic expression and activation has only recently been revealed in alcohol/HCV-associated HCC models. Alcohol feeding to mice expressing the HCV Ns5a in a hepatocyte specific manner aggravates liver inflammation via activation of overexpressed TLR4 in the parenchymal cells. Long-term alcohol feeding produces liver tumors in these transgenic mice in a manner dependent on TLR4. From these mice, CD133+/CD49f+ tumor-initiating stem cell-like cells (TICs) have been isolated. These TICs exhibit self-renewal and tumorigenic activities driven by TLR4-dependent upregulation of the stem cell factor NANOG. A defective TGF-β tumor suppressor pathway is identified in the TICs and mediated by NANOG target genes Igf2bp3 and Yap1. This TGF-β pathway antagonism is responsible in part for the TICs' tumorigenic activity and chemoresistance. Conversely, mice with an attenuated TGF-β pathway due to haploinsufficiency of β2-Spectrin, spontaneously develop liver tumors and alcohol feeding increases tumor incidence in a TLR4-dependent manner. This reciprocal antagonism between TLR4 and TGF-β pathways may serve as a novel therapeutic target for HCC.

Abstract 264: Mesenchymal stem cells mediate epithelial-to-mesenchymal transition (EMT) and stemness regulation in pancreatic cancer via Notch signal.

Abstract Cancer associate fibroblasts (CAFs), one of the major components of the cancer stroma, are prominently involved in tumor progression including epithelial to mesenchymal transition (EMT). Recently, bone marrow derived mesenchymal stem cells (MSCs) have been suggested as candidate for the source of tumor-promoting CAFs. We previously demonstrated that side population (SP) cells, which are enriched with so-called tumor initiating stem cell like cells (TISCs), play a pivotal role of local invasion and liver metastasis in pancreatic cancer (Int-J-Cancer 124:2771, 2009). Therefore, we formulated the hypothesis that MSCs regulate SP cells EMT and TISC-like properties such as tumor formation/progression. The AIM of the present study was to examine whether bone marrow-derived MSCs have ability to mediate EMT and/or tumor progression in pancreatic cancer SP cells. METHODS: MSCs were pre-treated with TGF-beta for 3 days. SP or non-SP cells were co-cultured in the presence or absence of TGF-beta-pretreated MSCs (Tb-MSCs) for 3 days. Real-time PCR experiments were performed to quantitate mRNA levels of EMT associated genes as well as so-called stemness related genes. PANC-1 derived SP or non-SP cells were co-injected with Tb-MSCs into NOD/SCID mice, and their tumorigenesity was evaluated. RESULTS: Co-culturing with Tb-MSCs dramatically induced EMT-associated mRNA alterations including suppression of E-cadherin and induction of slug in PANC-1 SP cells. In SP cells but not in non-SP cells, levels of stemness genes including CD133, Oct4, LGR5, were enhanced by co-culturing with Tb-MSCs. Tb-MSCs enhanced in vitro sphere forming activity as well as in vivo tumor formation in SP cells. These alterations including EMT-associated gene modifications and enhanced sphere formation were suppressed by Notch signal inhibition, suggested MSCs-associated regulation of EMT and TISC-like properties are mediated by Notch-signaling. In CONCLUSION, MSCs regulate EMT and they maintain TISC-like properties in pancreatic cancer SP cells via Notch signal-dependent mechanisms. Targeting Notch signaling would appear to be attractive to prevent MSCs and/or stromal cell-associated cancer progression. Citation Format: Ayano Kabashima-Niibe, Hajime Higuchi, Yumi Matsuzaki, Yo Mabuchi, Shinsuke Funakoshi, Masayuki Adachi, Yasuo Hamamoto, Hiromasa Takaishi, Toshifumi Hibi. Mesenchymal stem cells mediate epithelial-to-mesenchymal transition (EMT) and stemness regulation in pancreatic cancer via Notch signal. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 264. doi:10.1158/1538-7445.AM2013-264