Cancer Stem Cells Surface Research Articles

Targeting Hepatic Cancer Stem Cells (CSCs) and Related Drug Resistance by Small Interfering RNA (siRNA).

Tumor recurrence after curative therapy and hepatocellular carcinoma (HCC) cells' resistance to conventional therapies is the reasons for the worse clinical results of HCC patients. A tiny population of cancer cells with a strong potential for self-renewal, differentiation, and tumorigenesis has been identified as cancer stem cells (CSCs). The discovery of CSC surface markers and the separation of CSC subpopulations from HCC cells have been made possible by recent developments in the study of hepatic (liver) CSCs. Hepatic CSC surface markers include epithelial cell adhesion molecules (EpCAM), CD133, CD90, CD13, CD44, OV-6, ALDH, and K19. CSCs have a significant influence on the development of cancer, invasiveness, self-renewal, metastasis, and drug resistance in HCC, and thus provide a therapeutic chance to treat HCC and avoid its recurrence. Therefore, it is essential to develop treatment approaches that specifically and effectively target hepatic stem cells. Given this, one potential treatment approach is to use particular small interfering RNA (siRNA) to target CSC, disrupting their behavior and microenvironment as well as changing their epigenetic state. The characteristics of CSCs in HCC are outlined in this study, along with new treatment approaches based on siRNA that may be used to target hepatic CSCs and overcome HCC resistance to traditional therapies.

Colorectal Cancer Stem Cell Biomarkers: Biological Traits and Prognostic Insights.

Due to self-renewal, differentiation, and limitless proliferation properties, Cancer Stem Cells (CSCs) increase the probability of tumor development. These cells are identified by using CSC markers, which are highly expressed proteins on the cell surface of CSCs. Recently, the therapeutic application of CSCs as novel biomarkers improved both the prognosis and diagnosis outcome of colorectal Cancer. In the present review, we focused on a specific panel of colorectal CSC markers, including LGR5, ALDH, CD166, CD133, and CD44, which offers a targeted and comprehensive analysis of their functions. The selection criteria for these markers cancer were based on their established significance in Colorectal Cancer (CRC) pathogenesis and clinical outcomes, providing novel insights into the CSC biology of CRC. Through this approach, we aim to elevate understanding and stimulate further research for developing effective diagnostic and therapeutic strategies in CRC.

Cancer Stem Cell Metastatic Checkpoints and Glycosylation Patterns: Implications for Therapeutic Strategies

Cancer stem cells (CSCs), found within tumors, are powerful drivers of disease recurrence and metastasis. Their abilities to self-renew and maintain stem-like properties make treatment difficult, as their heterogeneity and metastatic properties can lead to resistance and limit the effectiveness of standard therapies. Given their significance, CSCs are typically isolated based on combinations of markers, which often indicate heterogeneous populations of CSCs. The lack of consensus in cell characterization poses challenges in defining and targeting these cells for effective therapeutic interventions. In this review, we suggest five promising molecules—ABCB5, CD26, CD66c, uPAR, and Trop-2—chosen specifically for their distinct distribution within cancer types and clinical relevance. These markers, expressed at the cell surface of CSCs, could significantly enhance the specificity of cancer stemness characterization. This review focuses on describing their pivotal roles as biomarker checkpoints for metastasis. Additionally, this review outlines existing literature on glycosylation modifications, which present intriguing epitopes aimed at modulating the stability and function of these markers. Finally, we summarize several promising in vivo and clinical trial approaches targeting the mentioned surface markers, offering potential solutions to overcome the therapeutic resistance of CSCs and addressing current gaps in treatment strategies.

Modeling 5-FU-Induced Chemotherapy Selection of a Drug-Resistant Cancer Stem Cell Subpopulation.

(1) Background: Cancer stem cells (CSCs) are a subpopulation of cells in a tumor that can self-regenerate and produce different types of cells with the ability to initiate tumor growth and dissemination. Chemotherapy resistance, caused by numerous mechanisms by which tumor tissue manages to overcome the effects of drugs, remains the main problem in cancer treatment. The identification of markers on the cell surface specific to CSCs is important for understanding this phenomenon. (2) Methods: The expression of markers CD24, CD44, ALDH1, and ABCG2 was analyzed on the surface of CSCs in two cancer cell lines, MDA-MB-231 and HCT-116, after treatment with 5-fluorouracil (5-FU) using flow cytometry analysis. A machine learning model (ML)-genetic algorithm (GA) was used for the in silico simulation of drug resistance. (3) Results: As evaluated through the use of flow cytometry, the percentage of CD24-CD44+ MDA-MB-231 and CD44, ALDH1 and ABCG2 HCT-116 in a group treated with 5-FU was significantly increased compared to untreated cells. The CSC population was enriched after treatment with chemotherapy, suggesting that these cells have enhanced drug resistance mechanisms. (4) Conclusions: Each individual GA prediction model achieved high accuracy in estimating the expression rate of CSC markers on cancer cells treated with 5-FU. Artificial intelligence can be used as a powerful tool for predicting drug resistance.

An Overview of CD133 as a Functional Unit of Prognosis and Treatment Resistance in Glioblastoma.

Biomarkers for resistance in Glioblastoma multiforme (GBM) are lacking, and progress in the clinic has been slow to arrive. CD133 (prominin-1) is a membrane-bound glycoprotein on the surface of cancer stem cells (CSCs) that has been associated with poor prognosis, therapy resistance, and tumor recurrence in GBM. Due to its connection to CSCs, to which tumor resistance and recurrence have been partially attributed in GBM, there is a growing field of research revolving around the potential role of CD133 in each of these processes. However, despite encouraging results in vitro and in vivo, the biological interplay of CD133 with these components is still unclear, causing a lack of clinical application. In parallel, omic data from biospecimens that include CD133 are beginning to emerge, increasing the importance of understanding CD133 for the effective use of these highly dimensional data sets. Given the significant mechanistic overlap, prioritization of the most robust findings is necessary to optimize the transition of CD133 to clinical applications using patient-derived biospecimens. As a result, this review aims to compile and analyze the current research regarding CD133 as a functional unit in GBM, exploring its connections to prognosis, the tumor microenvironment, tumor resistance, and tumor recurrence.

Putative Cancer Stem Cell Markers are Frequently Expressed by Melanoma Cells in Vitro and in Situ but are also Present in Benign Differentiated Cells.

Currently, there remains an incomplete view of cancer stem cells (CSCs) in solid tumours. We studied a panel of putative CSC surface markers (ALDH1A1, ABCG2, CD44v7/8, CD44v10, CD133, CD271, and Nestin) in 40 established melanoma cell lines and four early-passage melanoma strains by flow cytometry. We additionally examined 40 formalin-fixed paraffin-embedded melanoma tissues using immunofluorescence microscopy. This was compared with their expression in healthy skin, normal differentiated melanocytes and fibroblasts. Most of the putative CSC markers were expressed by both melanoma cell lines and tissues. When present, these proteins were expressed by the majority of cells in the population. However, the expression of these markers by cells in healthy skin sections, normal differentiated melanocytes, and fibroblasts revealed that differentiated non-malignant cells also expressed CSC markers indicating that they lack of specificity for CSCs. Culturing cell lines under conditions more characteristic of the tumour microenvironment upregulated CSC marker expressions in a proportion of cell lines, which correlated with improved cell growth and viability. The testing of melanoma cell lines (n = 40), early-passage cell strains (n = 4), and melanoma tissues (n = 40) showed that several putative CSC markers (ALDH1A1, ABCG2, CD44v7/8, CD44v10, CD133, CD271, and Nestin) are commonly present in a large proportion of melanoma cells in vitro and in situ. Further, we showed that these putative markers lack specificity for CSCs because they are also expressed in differentiated non-malignant cell types (melanocytes, fibroblasts, and skin), which could limit their use as therapeutic targets. These data are consistent with the emerging notion of CSC plasticity and phenotype switching within cancer cell populations.

Effect of microserum environment stimulation on extraction and biological function of colorectal cancer stem cells

Background3D cancer stem cell (CSC) cultures are widely used as in vitro tumor models. In this study, we determined the effects of enriching HCT116 tumor spheres initially cultured in serum-free medium with different concentrations of serum, focusing on the effect of microserum environment stimulation on extraction and biological function of colorectal cancer stem cells (CCSCs).MethodsCCSCs were enriched in standard serum-free medium and serum-free medium with different concentrations of serum for 1 week. The expression of CSC-associated markers in CCSCs, and the presence and relative proportion of CSCs (CD133/CD44 cell sorting) were then determined to elucidate the effect of the microserum environment on the preservation of CSC-related features. Further, the tumorigenic capacity of CCSCs was evaluated in an immunodeficiency mouse model.ResultsOur data indicated that a significantly greater number of spheres with a greater size range and high viability without drastic alteration in biological and structural features, which maintained self‐renewal potential after sequential passages were formed after serum supplementation. Real-time analysis showed that both serum spheres and serum-free spheres displayed similar expression patterns for key stemness genes. Serum spheres showed higher expression of the CSC surface markers CD133 and CD44 than did CSCs spheres cultured in serum-free medium. Adherent cultures in complete medium could adapt to the serum-containing microenvironment faster and showed higher proliferation ability. The addition of serum induced EMT and promoted the migration and invasion of serum globular cells. Compared with serum-free cells and adherent cells, serum spheres showed higher tumor initiation ability.ConclusionsMicroserum environment stimulation could be an effective strategy for reliable enrichment of intact CCSCs, and a more efficient CSC enrichment method.

Proanthocyanidins inhibited colorectal cancer stem cell characteristics through Wnt/β-catenin signaling.

Cancer stem cells (CSCs) play a key role in tumor cell growth, drug resistance, recurrence, and metastasis. Proanthocyanidins (PC) is widely existed in plants and endowed with powerful antioxidant and anti-aging effects. Interestingly, recent studies have found that PC exhibits the inhibitory effect on tumor growth. However, the role of PC in CSCs of colorectal cancer (CRC) and molecular mechanism remain unclear. CCK-8, colony, and tumorsphere formation assay were used to evaluate cancer cell viability and stemness, respectively. Western blotting was used to detect the protein expression. Tumor xenograft experiments were employed to examine the tumorigenicity of CRC cells in nude mice. PC decreased the proliferation of CRC cells (HT29 and HCT-116), and improved the sensitivity of CRC cells to oxaliplatin (L-OHP), as well as inhibited tumor growth in nude mice. Further studies showed that PC also down-regulated CSCs surface molecular and stemness transcriptional factors, while suppressed the formations of tumorspheres and cell colony in CRC. In addition, PC-impaired proteins expressions of p-GSK3β, β-catenin and DVL1-3. LiCl, an activator of the Wnt/β-catenin signaling, rescued PC-induced downregulation of CSCs markers, and reduction of tumorspheres and cell colony formation abilities in CRC cells. Furthermore, the effects of PC on inhibiting cell proliferation and enhancing L-OHP sensitivity were impaired by LiCl. PC exerted an inhibitory effect on CSCs via Wnt/β-catenin in CRC, and may be a potential new class of natural drug for CRC treatment.

CD24 blockade as a novel strategy for cancer treatment.

The CD24 protein is a heat-stable protein with a small core that undergoes extensive glycosylation. It is expressed on the surface of various normal cells, including lymphocytes, epithelial cells, and inflammatory cells. CD24 exerts its function by binding to different ligands. Numerous studies have demonstrated the close association of CD24 with tumor occurrence and progression. CD24 not only facilitates tumor cell proliferation, metastasis, and immune evasion but also plays a role in tumor initiation, thus, serving as a marker on the surface of cancer stem cells (CSCs). Additionally, CD24 induces drug resistance in various tumor cells following chemotherapy. To counteract the tumor-promoting effects of CD24, several treatment strategies targeting CD24 have been explored, such as the use of CD24 monoclonal antibodies (mAb) alone, the combination of CD24 and chemotoxic drugs, or the combination of these drugs with other targeted immunotherapeutic techniques. Regardless of the approach, targeting CD24 has demonstrated significant anti-tumor effects. Therefore, the present study focuses on anti-tumor therapy and provides a comprehensive review of the structure and fundamental physiological function of CD24 and its impact on tumor development, and suggests that targeting CD24 may represent an effective strategy for treating malignant tumors.

SOX9 knockout decreases stemness properties in colorectal cancer cells.

Colorectal cancer (CRC) is a leading cause of death worldwide. SRY-box transcription factor 9 (SOX9) participates in organogenesis and cell differentiation in normal tissues but has been involved in carcinogenesis development. Cancer stem cells (CSCs) are a small population of cells present in solid tumors that contribute to increased tumor heterogeneity, metastasis, chemoresistance, and relapse. CSCs have properties such as self-renewal and differentiation, which can be modulated by many factors. Currently, the role of SOX9 in the maintenance of the stem phenotype has not been well elucidated, thus, in this work we evaluated the effect of the absence of SOX9 in the stem phenotype of CRC cells. We knockout (KO) SOX9 in the undifferentiated CRC cell line HCT116 and evaluated their stemness properties using sphere formation assay, differentiation assay, and immunophenotyping. SOX9-KO affected the epithelial morphology of HCT116 cells and stemness characteristics such as its pluripotency signature with the increase of SOX2 as a compensatory mechanism to induce SOX9 expression, the increase of KLF4 as a differentiation feature, as well as the inhibition of the stem cell markers CD44 and CD73. In addition, SOX9-KO cells gain the epithelial-mesenchymal transition (EMT) phenotype with a significant upregulation of CDH2. Furthermore, our results showed a remarkable effect on first- and second-sphere formation, being SOX9-KO cells less capable of forming high-size-resistant spheres. Nevertheless, CSCs surface markers were not affected during the differentiation assay. Collectively, our findings supply evidence that SOX9 promotes the maintenance of stemness properties in CRC-CSCs.

Quinacrine inhibits HIF-1α/VEGF-A mediated angiogenesis by disrupting the interaction between cMET and ABCG2 in patient-derived breast cancer stem cells

BackgroundBreast cancer stem cells (BCSCs) have a critical role in progression of breast cancer by inducing angiogenesis. Several therapeutic strategies have been designed for the treatment of breast cancer by specifically preventing angiogenesis. But there is a dearth of study regarding the treatment procedure which can specifically target and kill the BCSCs and cause lesser harm to healthy cells of the body. A plant-based bioactive compound Quinacrine (QC) specifically kills cancer stem cells (CSCs) without harming healthy cells and also inhibits cancer angiogenesis but the detailed mechanistic study of its anti-CSCs and anti-angiogenic activity is yet to explore. HypothesisEarlier report showed that both cMET and ABCG2 play an essential role in cancer angiogenesis. Both are present on the cell surface of CSCs and share an identical ATP-binding domain. Interestingly, QC a plant based and bioactive compound which was found to inhibit the function of CSCs marker cMET and ABCG2. These relevant evidence led us to hypothesize that cMET and ABCG2 may interact with each other and induce the production of angiogenic factors, resulting in activation of cancer angiogenesis and QC might disrupt the interaction between them to stop this phenomena. MethodsCo-immunoprecipitation assay, immunofluorescence assay, and western blotting were performed by using ex vivo patient-derived breast cancer-stem-cells (PDBCSCs) and human umbilical vein endothelial cells (HUVECs). In silico study was carried out to check the interaction between cMET and ABCG2 in presence or absence of QC. Tube formation assay using HUVECs and in ovo Chorioallantoic membrane (CAM) assay using chick fertilized eggs were performed to monitor angiogenesis. In vivo patient-derived xenograft (PDX) mice model was used to validate in silico and ex vivo results. ResultsData revealed that in a hypoxic tumor microenvironment (TME), cMET and ABCG2 interact with each other and upregulate HIF-1α/VEGF-A axis to induce breast cancer angiogenesis. In silico and ex vivo study showed that QC disrupted the interaction between cMET and ABCG2 to inhibit the angiogenic response in endothelial cells by reducing the secretion of VEGF-A from PDBCSCs within the TME. Knockdown of cMET, ABCG2 or both, significantly downregulated the expression of HIF-1α and reduced the secretion of pro-angiogenic factor VEGF-A in the TME of PDBCSCs. Additionally, when PDBCSCs were treated with QC, similar experimental results were obtained. ConclusionIn silico, in ovo, ex vivo and in vivo data confirmed that QC inhibited the HIF-1α/VEGF-A mediated angiogenesis in breast cancer by disrupting the interaction between cMET and ABCG2.

Abstract 5048: Combatting pancreatic cancer stem cells by novel titanium peroxides nanoparticles combined with X-ray radiation

Abstract Background: Radiotherapy is widely used as the main treatment for multiple malignancies. However, several types of cancers, including pancreatic cancer, show resistance to radiation therapy. The presence of cancer stem cells (CSCs) are the major cause of radiation resistance in pancreatic cancer. Whereas, titanium peroxides nanoparticles (TiOxNPs) which are a modified form of titanium oxide nanoparticles promote enhanced remarkable efficacy of radiation therapy. Therefore, we examined the efficacy of TiOxNPs as radiosensitizers to eradicate pancreatic cancer stem cells. Methods and materials: In vitro, Sphere-forming assay, survival assay, migration, and invasion assay were evaluated after using TiOxNPs prior to radiation exposure to pancreatic cancer cell line. In vivo, tumor-bearing nude mice were injected by TiOxNPs either intratumoral or intravenous one hour prior to radiation treatment, and the tumor volume, body weight, and mice survival was calculated. In addition, proteins-related stemness were measured in vitro and in vivo to evaluate the usage of TiOxNPs as radiosensitizers to pancreatic CSCs. Moreover, we planned to evaluate the mechanism beyond the efficacy of TiOxNPs as radiosensitizers to CSCs by detecting reactive oxygen species (ROS) production, mitochondrial function, and the phosphorylation of some signaling proteins. We found that TiOxNPs combined with ionizing radiation showed anti-cancer effects on radioresistant CSCs both in vitro and in vivo. Results: In vitro, a marked reduction in growth was detected after exposing the TiOxNPs-treated cells to radiation therapy, specifically with a 5Gy dose compared with 2Gy dose. TiOxNPs exhibited a synergistic effect with radiation on pancreatic CSC-enriched spheres by downregulating self-renewal regulatory factors and CSC surface markers. In vivo, we first established an aggressive xenograft by injecting MIA PaCa-2 sphere cells into the flank region of BALB/c nude mice, and found that animals treated with combined TiOxNPs and irradiation showed a dramatic reduction in tumor volume and weight compared to the untreated group. Moreover, combined treatment suppressed epithelial-mesenchymal transition, migration, and invasion properties in primary and aggressive pancreatic cancer cells by reducing the expression of proteins relevant to these processes. Radiosensitizing TiOxNPs suppressed pancreatic xenograft outgrowth after primary or dissociating sphere MIA PaCa-2 cell implantation. It is assumed that synergy is created by inactivating the AKT signaling pathway and producing unbearable amounts of ROS. Conclusion: Our findings showed that using TiOxNPs in combination with radiation might be a favorable therapeutic approach to eradicate pancreatic CSCs. Citation Format: Mohammed Salah, Hiroki Kawaguchi, Hiroaki Akasaka, Yasuyuki Shimizu, Kenta Morita, Yuya Nishimura, Hikaru Kubota, Tomomi Sogawa, Naritoshi Mukumoto, Chiaki Ogino, Ryohei Sasaki. Combatting pancreatic cancer stem cells by novel titanium peroxides nanoparticles combined with X-ray radiation. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5048.

Abstract 4105: Improvement of CD133-specific chimeric antigen receptor T cells by secreting anti-PD-L1 single-chain variable fragment against cholangiocarcinoma

Abstract Cholangiocarcinoma (CCA) is rare but hard-to-treat solid cancer affecting people worldwide. Cancer stem cells (CSCs) in CCA contribute to tumor heterogeneity and resistance to conventional therapies. Thus, CSCs are notable targets for cancer immunotherapy. CD133 is a potential CSC surface marker overexpressed in various cancers. T cell-based immunotherapy, namely chimeric antigen receptor (CAR) T-cell targeting CD133 has shown potential in eradication of some solid tumors including CCA. Nevertheless, anti-tumor function of CAR T cell could be decreased under immunosuppressive tumor microenvironment (TME). Thus, to improve its function under TME, the next-generation of CD133-specific CAR T-cell is required. We therefore constructed two lentiviral vectors containing: (i) anti-CD133 single-chain variable fragment (scFv), 4-1BB costimulatory molecule, and CD3ζ (133CAR), and (ii) anti-CD133 scFv, 4-1BB, and CD3ζ in tandem with anti-PD-L1 scFv (133CARsL). The lentiviruses were transduced to generate CD133-specific CAR T cells expressing the second-generation (133CART) or anti-CD133 CAR with self-secreting anti-PD-L1 scFv (133CARTsL). The latter was able to simultaneously target CD133 and PD-L1 molecules on CCA cells. CCA cells endogenously expressing CD133 and PD-L1 were cocultured with either 133CART or 133CARTsL. In short-term coculture, the antitumor effects of 133CARTsL were not different from that of 133CART. However, in long-term coculture and after tumor re-challenge, 133CARTsL showed lower expression of programmed cell death protein (PD-1) and better cytotoxic function against high CD133 and PD-L1 CCA cells. The higher potential of 133CARTsL with reduced exhaustion profile would offer great promise for application of CD133-targeting CAR T cells in solid tumors. Citation Format: Thanich Sangsuwannukul, Kamonlapat Supimon, Thaweesak Chieochansin, Kornkan Choomee, Jatuporn Sujjitjoon, Mutita Junking, Pa-thai Yenchitsomanus. Improvement of CD133-specific chimeric antigen receptor T cells by secreting anti-PD-L1 single-chain variable fragment against cholangiocarcinoma. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4105.

Application of AlDeSense to Stratify Ovarian Cancer Cells Based on Aldehyde Dehydrogenase 1A1 Activity.

Relapse after cancer treatment is often attributed to the persistence of a subpopulation of tumor cells known as cancer stem cells (CSCs), which are characterized by their remarkable tumor-initiating and self-renewal capacity. Depending on the origin of the tumor (e.g., ovaries), the CSC surface biomarker profile can vary dramatically, making the identification of such cells via immunohistochemical staining a challenging endeavor. On the contrary, aldehyde dehydrogenase 1A1 (ALDH1A1) has emerged as an excellent marker to identify CSCs, owing to its conserved expression profile in nearly all progenitor cells including CSCs. The ALDH1A1 isoform belongs to a superfamily of 19 enzymes that are responsible for the oxidation of various endogenous and xenobiotic aldehydes to the corresponding carboxylic acid products. Chan et al. recently developed AlDeSense, an isoform-selective "turn-on" probe for the detection of ALDH1A1 activity, as well as a non-reactive matching control reagent (Ctrl-AlDeSense) to account for off-target staining. This isoform-selective tool has already been demonstrated to be a versatile chemical tool through the detection of ALDH1A1 activity in K562 myelogenous leukemia cells, mammospheres, and melanoma-derived CSC xenografts. In this article, the utility of the probe was showcased through additional fluorimetry, confocal microscopy, and flow cytometry experiments where the relative ALDH1A1 activity was determined in a panel of five ovarian cancer cell lines.

Cancer Stem Cells in Hepatocellular Carcinoma: Intrinsic and Extrinsic Molecular Mechanisms in Stemness Regulation.

Hepatocellular carcinoma (HCC) remains the most predominant type of liver cancer with an extremely poor prognosis due to its late diagnosis and high recurrence rate. One of the culprits for HCC recurrence and metastasis is the existence of cancer stem cells (CSCs), which are a small subset of cancer cells possessing robust stem cell properties within tumors. CSCs play crucial roles in tumor heterogeneity constitution, tumorigenesis, tumor relapse, metastasis, and resistance to anti-cancer therapies. Elucidation of how these CSCs maintain their stemness features is essential for the development of CSCs-based therapy. In this review, we summarize the present knowledge of intrinsic molecules and signaling pathways involved in hepatic CSCs, especially the CSC surface markers and associated signaling in regulating the stemness characteristics and the heterogeneous subpopulations within the CSC pool. In addition, we recapitulate the effects of crucial extrinsic cellular components in the tumor microenvironment, including stromal cells and immune cells, on the modulation of hepatic CSCs. Finally, we synopsize the currently valuable CSCs-targeted therapy strategies based on intervention in these intrinsic and extrinsic molecular mechanisms, in the hope of shedding light on better clinical management of HCC patients.

Targeting Cancer Stem Cells: Therapeutic and diagnostic strategies by the virtue of nanoparticles.

Cancer stem cells (CSCs) are the subpopulation of cells present within a tumor with the properties of self-renewing, differentiating, and proliferating. Owing to the presence of ATP-binding cassette drug pumps and increased expression of anti-apoptotic proteins, the conventional chemotherapeutic agents have failed to eliminate CSCs resulting in relapse and resistance of cancer. Therefore, to obtain long-lasting clinical responses and avoid the recurrence of cancer, it is crucial to develop an efficient strategy targeting CSCs by either employing a differentiation therapy or specifically delivering drugs to CSCs. Several intracellular and extracellular cancer specific biomarkers are overexpressed by CSCs and are utilized as targets for the development of new approaches in the diagnosis and treatment of CSCs. Moreover, several nanostructured particles, alone or in combination with current treatment approaches, have been used to improve the detection, imaging, and targeting of CSCs, thus addressing the limitations of cancer therapies. Targeting CSC surface markers, stemness-related signaling pathways, and tumor microenvironmental signals has improved the detection and eradication of CSCs and, therefore, tumor diagnosis and treatment. This review summarizes a variety of promising nanoparticles targeting the surface biomarkers of CSCs for the detection and eradication of tumor-initiating stem cells, used in combination with other treatment regimens.

Fluorescence Detection of Cancer Stem Cell Markers Using a Sensitive Nano-Aptamer Sensor.

Antigen CD133 is a glycoprotein present on the surface of cancer stem cells (CSCs), which is a key molecule to regulate the fate of stem cells and a functional marker of stem cells. Herein, a novel fluorescence “turn-on” nano-aptamer sensor for quantifying CD133 was designed using hybridization between CD133-targeted aptamers and partially complementary paired RNA (ssRNA), which were modified on the surface of quantum dots (QDs) and gold nanoparticles (AuNPs), respectively. Owing to the hybridization of aptamers and ssRNA, the distance between QDs and AuNPs was shortened, which caused fluorescence resonance energy transfer (FRET) between them, and the florescence of QDs was quenched by AuNPs. When CD133 competitively replaced ssRNA and was bound to aptamers, AuNPs-ssRNA could be released, which led to a recovery of fluorescent signals of QDs. The increase in the relative value of fluorescence intensity was investigated to linearly correlate with the CD133 concentration in the range of 0–1.539 μM, and the detection limit was 6.99 nM. In confocal images of A549 cells, the CD133 aptamer sensor was further proved applicable in lung cancer cell samples with specificity, precision, and accuracy. Compared with complicated methods, this study provided a fresh approach to develop a highly sensitive and selective detection sensor for CSC markers.

Abstract 6218: Oncolytic Seneca Valley virus (SVV-001) overcomes checkpoint inhibitor resistance and demonstrates a systemic anti-tumor immune response in a syngeneic pancreatic cancer murine model

Abstract Here we evaluated the efficacy of Seneca Valley Virus (SVV), an oncolytic virus in the Picornaviridae family, in combination with checkpoint inhibitors (CPI) using the CPI-resistant murine syngeneic pancreatic tumor model Pan02. SVV, serendipitously identified in 2001, is an extremely tumor selective and potent oncolytic virus for a variety of solid human cancers, primarily due to the expression of the receptor of SVV, TEM8, being selectively expressed on the surface of malignant cancer cells and cancer stem cells within a variety of solid tumors. SVV has been tested in three clinical trials of patients having neuroendocrine neoplasms as a single intravenous dose monotherapy. Despite this, the results were encouraging with patients having evidence of clinical benefit and only one DLT was reported in the 76 patients treated. Recent data have demonstrated that some oncolytic viruses can enhance efficacy in preclinical models and in clinical trials when the oncolytic virus was injected intratumorally in combination with systemic administration of a CPI(s). The mechanism is primarily believed to be due to the oncolytic virus enhancing T cell infiltration and fostering an anti-tumor immune response. SVV was injected intra-tumorally in Pan02 tumors along with aPD1and/or aCTLA4. SVV reversed any resistance to CPIs and enhanced efficacy over CPI(s) alone resulting in complete cures in >83% of mice with primary and abscopal tumors. SVV plus aPD1+aCTLA4 resulted in 5 of 6 mice cured of their primary tumor. The animals were challenged on their contralateral flank with Pan02 to evaluate systemic and abscopal immune effects. All mice (5/5) that cleared the primary Pan02 tumor also eradicated the abscopal secondary tumors. Control treated Pan02 tumor-bearing mice were all sacrificed due to tumor burden by day 70 (median survival <50 days). Control animals treated with aPD1+aCTLA4 showed transient tumor regressions but these animals all grew large tumors, requiring sacrifice. In contrast, the SVV+aPD1+aCTLA4 primary tumors were eliminated within 44 days and these animals remain tumor-free out to >110+ days. Contralateral tumors were eradicated in all 5 animals that rejected the primary tumor, demonstrating potent systemic immunity. In the control aPD1+aCTLA4 group, only one animal with contralateral tumor showed prolonged tumor regression. SVV treatment caused increases in T-cell infiltration; the combination of SVV+aPD1+aCTLA4 showing the highest infiltration. Phenotypic and gene expression analyses of infiltrating cells will be presented. These studies serve as a foundation for translating SVV oncolytic virotherapy combined with anti-PD-1 and anti-CTLA4 antibodies in patients with neuroendocrine neoplasms with a clinical trial anticipated to begin in H1, 2021. Citation Format: Paul L. Hallenbeck, Sunil Chada. Oncolytic Seneca Valley virus (SVV-001) overcomes checkpoint inhibitor resistance and demonstrates a systemic anti-tumor immune response in a syngeneic pancreatic cancer murine model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6218.

Reactive oxygen species-inducing titanium peroxide nanoparticles as promising radiosensitizers for eliminating pancreatic cancer stem cells

BackgroundDespite recent advances in radiotherapy, radioresistance in patients with pancreatic cancer remains a crucial dilemma for clinical treatment. Cancer stem cells (CSCs) represent a major factor in radioresistance. Developing a potent radiosensitizer may be a novel candidate for the eradication of pancreatic CSCs.MethodsCSCs were isolated from MIA PaCa-2 and PANC1 human pancreatic cancer cell lines. Titanium peroxide nanoparticles (TiOxNPs) were synthesized from titanium dioxide nanoparticles (TiO2NPs) and utilized as radiosensitizers when added one hour prior to radiation exposure. The antitumor activity of this novel therapeutic strategy was evaluated against well-established pancreatic CSCs model both in vitro and in vivo.ResultsIt is shown that TiOxNPs combined with ionizing radiation exhibit anti-cancer effects on radioresistant CSCs both in vitro and in vivo. TiOxNPs exhibited a synergistic effect with radiation on pancreatic CSC-enriched spheres by downregulating self-renewal regulatory factors and CSC surface markers. Moreover, combined treatment suppressed epithelial-mesenchymal transition, migration, and invasion properties in primary and aggressive pancreatic cancer cells by reducing the expression of proteins relevant to these processes. Notably, radiosensitizing TiOxNPs suppressed the growth of pancreatic xenografts following primary or dissociating sphere MIA PaCa-2 cell implantation. It is inferred that synergy is formed by generating intolerable levels of reactive oxygen species (ROS) and inactivating the AKT signaling pathway.ConclusionsOur data suggested the use of TiOxNPs in combination with radiation may be considered an attractive therapeutic strategy to eliminate pancreatic CSCs.

SYT-SSX1 enhances the invasiveness and maintains stem-like cell properties in synovial sarcoma via induction of TGF-\u03b21/Smad signaling

BackgroundSynovial sarcoma (SS) is a type of soft tissue sarcoma (STS) of undetermined tissue origin, which is characterized by the recurrent pathognomonic chromosomal translocation t (X;18)(p11.2; q11.2). Studies have shown that SS is a malignant tumor originating from cancer stem cells or pluripotent mesenchymal stem cells and may be related to fusion genes. In addition, some studies have indicated that the induction of epithelial–mesenchymal transition (EMT) via the TGF-β1/Smad signaling pathway leads to SS metastasis.MethodsWe analyzed the effects of SYT-SSX1 on the stemness of SS cells via TGF-β1/Smad signaling in vitro. The SYT-SSX1 fusion gene high expression cell was constructed by lentiviral stable transfer technology. SYT-SSX1 and SW982 cells were cultured and tested for sphere-forming ability. The transwell migration assay and flow cytometry were used to assess the migration ability of the sphere cells as well as the expression of CSC-related markers. We treated SYT-SSX1 cells with rhTGF-β1 (a recombinant agent of the TGF-β1 signaling pathway) and SB431542 and observed morphological changes. A CCK-8 experiment and a western blot (WB) experiment were conducted to detect the expression of TGF-β1 signaling pathway- and EMT-related proteins after treatment. The SYT-SSX1 cells were then cultured and their ability to form spheres was tested. Flow cytometry, WB, and quantitative real-time polymerase chain reaction (qRT-PCR) were used to detect the expression of CSC surface markers on SYT-SSX1 sphere cells.ResultsIt was found that SYT-SSX1 has stronger sphere-forming ability, migration ability, and higher expression of CSC-related molecules than SW982 cells. Through treating SYT-SSX1 and SW982 cells with rhTGF-β1 and SB431542, we found that TGF-β1 enhanced the proliferation of cells, induced EMT, and that TGF-β1 enhanced the characteristics of tumor stem cells.ConclusionsOur results suggest that SYT-SSX1 enhances invasiveness and maintains stemness in SS cells via TGF-β1/Smad signaling. These findings reveal an effective way to potentially improve the prognosis of patients with SS by eliminating the characteristics of cancer stem cells (CSCs) during treatment.