Promotes Cancer Stem Cell Research Articles

Abstract B036: WEE1 confers resistance to PD-1 blockade via hyperactivation of the AKT signaling pathway

Abstract Immune checkpoint blockade (ICB) has revolutionized cancer treatment, but resistance limits its clinical effectiveness. Therefore, understanding immune resistance mechanisms and identifying predictive markers are essential. Our transcriptomic analysis of PD-1 blockade-treated patients and non-responsive tumor models identifies WEE1 as a key resistance factor, promoting cancer stem cell (CSC)-like traits and immune resistance phenotypes including low T cell infiltrated into tumor and anti-apoptotic properties to cytotoxic T cells (CTLs). WEE1 drives AKT hyperactivation, enhancing expression of resistance factors such as CYCLIN A which contributes to CSC-like properties, and the anti-apoptotic molecule MCL-1, while also reducing T cell infiltration via CXCL10 downregulation. This signaling axis is conserved across various cancers. Notably, WEE1 inhibition sensitizes tumors to ICB by disrupting these refractory properties and reinvigorating antitumor immunity. These findings underscore the novel role of WEE1 in driving immune resistance and CSC-like characteristics, supporting the use of WEE1 inhibitors as a strategy to overcome resistance to anti-PD-1 therapy. Citation Format: Hyo-Jung Lee, Suyeon Kim, Eunho Cho, Tae Woo Kim. WEE1 confers resistance to PD-1 blockade via hyperactivation of the AKT signaling pathway [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr B036.

Deciphering colorectal cancer radioresistance and immune microrenvironment: unraveling the role of EIF5A through single-cell RNA sequencing and machine learning.

Radiotherapy (RT) is a critical component of treatment for locally advanced rectal cancer (LARC), though patient response varies significantly. The variability in treatment outcomes is partly due to the resistance conferred by cancer stem cells (CSCs) and tumor immune microenvironment (TiME). This study investigates the role of EIF5A in radiotherapy response and its impact on the CSCs and TiME. Predictive models for preoperative radiotherapy (preRT) response were developed using machine learning, identifying EIF5A as a key gene associated with radioresistance. EIF5A expression was analyzed via bulk RNA-seq and single-cell RNA-seq (scRNA-seq). Functional assays and in vivo experiments validated EIF5A's role in radioresistance and TiME modulation. EIF5A was significantly upregulated in radioresistant colorectal cancer (CRC) tissues. EIF5A knockdown in CRC cell lines reduced cell viability, migration, and invasion after radiation, and increased radiation-induced apoptosis. Mechanistically, EIF5A promoted cancer stem cell (CSC) characteristics through the Hedgehog signaling pathway. Analysis of the TiME revealed that the radiation-resistant group had an immune-desert phenotype, characterized by low immune cell infiltration. In vivo experiments showed that EIF5A knockdown led to increased infiltration of CD8+ T cells and M1 macrophages, and decreased M2 macrophages and Tregs following radiation therapy, thereby enhancing the radiotherapy response. EIF5A contributes to CRC radioresistance by promoting CSC traits via the Hedgehog pathway and modulating the TiME to an immune-suppressive state. Targeting EIF5A could enhance radiation sensitivity and improve immune responses, offering a potential therapeutic strategy to optimize radiotherapy outcomes in CRC patients.

TESC associated with poor prognosis enhances cancer stemness and migratory properties in liver cancer

Liver cancer stem cells (LCSCs) are responsible for recurrence, metastasis, and drug resistance in liver cancer. However, the genes responsible for inducing LCSCs have not been fully identified. Based on our previous study, we found that tescalcin (TESC), a calcium-binding EF hand protein that plays a crucial role in chromatin remodeling, transcriptional regulation, and epigenetic modifications, was up-regulated in LCSCs of spheroid cultures. By searching the Cancer Genome Atlas, International Cancer Genome Consortium, Human Protein Atlas, and Kaplan–Meier Plotter databases, we found that TESC expression was significantly elevated in liver cancer compared with that in normal liver tissue and was predictive of a decreased overall survival rate. Multivariate Cox analysis revealed TESC to be an independent prognostic factor for survival. High TESC expression was positively associated with cancer stem cell pathways, cancer stem cell surface markers, stemness transcription factors, epithelial–mesenchymal transition (EMT) factors, immune checkpoint proteins, and various cancer-related biological processes in liver cancer. Furthermore, TESC was implicated as promoting cancer stem cell properties through its influence on EMT. We demonstrated that TESC is a novel stemness-related gene that can serve as an independent prognostic factor for liver cancer.

Understanding the role of miRNAs in cervical cancer pathogenesis and therapeutic responses.

Cervical cancer (CC) is the most common cancer in women and poses a serious threat to health. Despite familiarity with the factors affecting its etiology, initiation, progression, treatment strategies, and even resistance to therapy, it is considered a significant problem for women. However, several factors have greatly affected the previous aspects of CC progression and treatment in recent decades. miRNAs are short non-coding RNA sequences that regulate gene expression by inhibiting translation of the target mRNA. miRNAs play a crucial role in CC pathogenesis by promoting cancer stem cell (CSC) proliferation, postponing apoptosis, continuing the cell cycle, and promoting invasion, angiogenesis, and metastasis. Similarly, miRNAs influence important CC-related molecular pathways, such as the PI3K/AKT/mTOR signaling pathway, Wnt/β-catenin system, JAK/STAT signaling pathway, and MAPK signaling pathway. Moreover, miRNAs affect the response of CC patients to chemotherapy and radiotherapy. Consequently, this review aims to provide an acquainted summary of onco miRNAs and tumor suppressor (TS) miRNAs and their potential role in CC pathogenesis and therapy responses by focusing on the molecular pathways that drive them.

Retraction Note: Platelet-derived growth factor receptor-α and -β promote cancer stem cell phenotypes in sarcomas

Retraction Note: Platelet-derived growth factor receptor-α and -β promote cancer stem cell phenotypes in sarcomas

Abstract 5877: Disulfiram and its metal complexes reversed hypoxia induced stemness and synergized with first line drugs in primary patient derived pancreatic ductal adenocarcinoma cells

Abstract Pancreatic ductal adenocarcinoma (PDAC) has a dismal 5-year survival rate (12%) and is predicted to become the second leading cause of cancer related deaths by 2030. The main treatment option for advanced PDAC, gemcitabine (GEM) and nab-paclitaxel (PAC) chemotherapy, has limited efficacy due to adverse toxicities and chemoresistance. Extensive desmoplasia in the PDAC microenvironment induces hypoxia that drives epithelial to mesenchymal transition (EMT) and promotes cancer stem cells (CSCs) leading to metastasis and acquired resistance. Drugs that target CSCs and EMT to overcome chemoresistance could improve patient outcome. Disulfiram (DSF), an FDA approved anti alcoholism drug, has excellent anticancer activity on chelation with Cu2+/Zn2+ ions to form the anticancer metabolites, Copper or Zinc Diethyldithiocarbamate (CuDDC or ZnDDC). The anticancer application of the current oral version of DSF is prevented by its short plasma half-life (< 4 minutes) and separate administration of oral Cu/Zn supplement leading to bioavailability issues. A stable, long circulating, injectable formulation of DSF, CuDDC or ZnDDC may overcome these pharmacokinetic issues. In this study albumin was used to develop soluble, stable and homogenous CuDDC and ZnDDC nanoparticles (Alb-CuDDC, Alb-ZnDDC) and their efficacy was compared with free DSF-Cu in a panel of normoxic, hypoxic and spheroid cultures of patient PDAC cells derived from primary, circulating and metastatic sites. Hypoxia and spheroid cultures of PDAC cells were highly resistant to GEM and PAC and had increased expression of CSC markers such as ALDH, CD133, ABCG2 and CA9. Alb-CuDDC and Alb-ZnDDC were cytotoxic to all PDAC cells (IC50s ~300 nM and ~7000 nM, respectively) in normoxia and hypoxia and synergized with GEM and PAC. While DSF-Cu and Alb-CuDDC significantly reduced the expression of CSC markers and inhibited sphere reformation and migration of PDAC cells, Alb-ZnDDC was less effective in inhibiting these features. Therefore, the ability of PDAC cells to acquire resistance to Alb-ZnDDC was investigated. After long term exposure (> 4 months) to increasing doses of each drug (DSF-Cu, Alb-CuDDC and Alb-ZnDDC), PANC1 and BXPC3 PDAC cells acquired resistance only to Alb-ZnDDC. PANC1ZR6 and BXPC3ZR5 resistant cells showed increased expression of CSC markers and significant cross-resistance to PAC and GEM suggesting multidrug resistance. Importantly, no cross-resistance to Alb-CuDDC or DSF-Cu was observed, suggesting alternative mechanisms for Alb-ZnDDC. RNA sequencing is underway to identify potential mechanisms involved. To conclude, albumin formulation improved the solubility and stability of DSF-metal complexes. Alb-CuDDC targets CSCs and overcomes resistance in PDAC, similar to free DSF-Cu. Alb-ZnDDC may have alternative mechanisms which are yet to be elucidated. Citation Format: Benjamin J. Small, Ogechi Nkeonye, Vinodh Kannappan, Shalini Kumarasamy, Kate Butcher, Karim Azar, Gowtham Rajendran, Yoshitha Lakshmanan Lakshmanan, Mark Morris, Christopher Heeschen, Yaohe Wang, Weiguang Wang. Disulfiram and its metal complexes reversed hypoxia induced stemness and synergized with first line drugs in primary patient derived pancreatic ductal adenocarcinoma cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5877.

Abstract 3037: Sex-specific differences in Yap1 and Cd276 function and expression regulate medulloblastoma progression and immune evasion

Abstract Unveiling the molecular mechanisms underlying sex-specific differences in cancer initiation, progression and treatment outcomes will provide novel insights that will advance cancer research and clinical care. This study highlights an unexpected, sex-biased role of the oncogene Yap1 in SHH medulloblastoma (MB). We discovered that Yap1 deletion in SmoM2-driven SHH MB significantly prolongs survival in male but not female mice. Using an integrated multi-omics approach, we show that YAP1 promotes cancer stem cell maintenance through concurrent transcriptional activation of stemness genes, such as Sox2, and repression of differentiation genes such as NeuroD1 and Zic1/2. Interestingly, while Yap1 is essential for maintaining cancer stem cells in both sexes, it plays a more critical role in immune evasion in males. Specifically, YAP1 regulates the expression of an immune checkpoint molecule Cd276 to suppress T cell function. Blocking CD276 or deleting Yap1 is sufficient to significantly reverse T cell suppression in males but not females. Furthermore, YAP1 direct targets of transcriptional regulation, including CD276, predicts survival in male but not female patients across multiple human cancers, suggesting that our findings have broader implications beyond medulloblastomas and is conserved across species. This study provides compelling evidence for male-biased susceptibility to Yap1 inhibition and uncovers the YAP1-CD276 axis as a sexually diverse pathway in T cell suppression in tumors. Citation Format: Nourhan Abdelfattah, Sivaraman Natarajan, Han Nhat Tran, Jose Maldonado, Rachael McMinimy, Hannah Borland, Shu-hsia Chen, Fernando Camargo, James Olson, Joshy George, Kyuson Yun. Sex-specific differences in Yap1 and Cd276 function and expression regulate medulloblastoma progression and immune evasion [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3037.

Abstract 762: The combination of EPA and naproxen suppresses colon tumorigenesis via altering the TME, and promoting epithelial maturation in cancerous crypts

Abstract Introduction: Colorectal cancer (CRC) is a leading cause of cancer-associated mortality. Our recent study in Pirc rats revealed that the combination of eicosapentaenoic acid and sodium naproxen exhibited additive tumor protection. While the results from this preclinical study were impressive, showing tumor suppression in excess of 95%, potential mechanisms underlying this tumor protection remain unclear. The purpose of this study was to determine the transcriptomic changes resulting in the tumor suppression afforded by the combination of EPA and naproxen supplementation in the diet. Methods: Six week-old Pirc rats were fed either a control AIN-93G diet, or AIN-93G diet supplemented with 2% EPA combined with 200 ppm naproxen, for a total of 20 weeks. Global transcriptomic analysis was performed using RNA sequencing (RNA-Seq) of colon tumors and tumor-adjacent normal tissue from 26-week-old Pirc rats. 100-bp paired-end sequencing was performed on an Illumina NovaSeq to a depth of 25 million reads per sample. Reads were trimmed with Trimmomatic-v0.39, and reads were mapped to the mRatBN7.2.105 rat reference genome using HISAT2. Differentially expressed genes were calculated using DESeq2, and gene set enrichment analysis (GSEA) were performed using Rstudio. Results: DESeq2 identified 809 differentially expressed genes (DEGs, 2-fold change > 1, FDR < 0.05) between large tumors from AIN-93G fed rats versus suppressed tumors from rats fed the combination of EPA and naproxen (490 up-regulated, 319 down-regulated). GSEA analysis revealed activation of inflammatory pathways including IL-17 signaling, JAK-STAT signaling, complement activation, cytokine signaling, ribosome biogenesis, and cell cycle were enriched in untreated control. In contrast, suppressed tumors from animals supplemented with EPA and naproxen were enriched in pathways including negative regulation of Wnt signaling, cell fate specification, ion channel complexes, and nutrient absorption. Furthermore, suppressed tumors shared significant GSEA pathway overlap with normal tissue, leading us to believe the combination of EPA and naproxen may be preventing tumorigenesis in part by maintaining cells in a differentiated state. Conclusion and Future directions: Inflammation plays a key role in tumorigenesis and promoting cancer stem cell niches in tumors. According to our analysis, the combination of EPA and naproxen attenuated cancer-associated inflammation and reduced proliferation in part by augmenting tumor differentiation. Future studies will utilize single-nuclei RNA-Seq (snRNA-Seq) to determine at a single cell resolution the transcriptomic changes of epithelial and stromal populations within the TME. This work was supported by National Cancer Institute task order 75N91019F00132. Citation Format: Ryan Beach, Michael Martinez, Vignesh Gunasekharan, Daniel W. Rosenberg. The combination of EPA and naproxen suppresses colon tumorigenesis via altering the TME, and promoting epithelial maturation in cancerous crypts [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 762.

Low-Dose Sorafenib Promotes Cancer Stem Cell Expansion and Accelerated Tumor Progression in Soft Tissue Sarcomas.

The cancer stem cell (CSC) hypothesis postulates that heterogeneous human cancers harbor a population of stem-like cells which are resistant to cytotoxic therapies, thus providing a reservoir of relapse following conventional therapies like chemotherapy and radiation (RT). CSCs have been observed in multiple human cancers, and their presence has been correlated with worse clinical outcomes. Here, we sought to evaluate the impact of drug dosing of the multi-tyrosine kinase inhibitor, sorafenib, on CSC and non-CSCs in soft tissue sarcoma (STS) models, hypothesizing differential effects of sorafenib based on dose and target cell population. In vitro, human cancer cell lines and primary STS from surgical specimens were exposed to escalating doses of sorafenib to determine cell viability and expression of CSC marker aldehyde dehydrogenase (ALDH). In vivo, ALDHbright CSCs were isolated, exposed to sorafenib, and xenograft growth and survival analyses were performed. We observed that sarcoma CSCs appear to paradoxically respond to the tyrosine kinase inhibitor sorafenib at low doses with increased proliferation and stem-like function of CSCs, whereas anti-viability effects dominated at higher doses. Importantly, STS patients receiving neoadjuvant sorafenib and RT on a clinical trial (NCT00864032) showed increased CSCs post therapy, and higher ALDH scores post therapy were associated with worse metastasis-free survival. These data suggest that low-dose sorafenib may promote the CSC phenotype in STS with clinically significant effects, including increased tumor growth and higher rates of metastasis formation in sarcoma patients.

MACC1 Regulates LGR5 to Promote Cancer Stem Cell Properties in Colorectal Cancer

Colorectal cancer (CRC) is one of the leading causes of cancer-related deaths worldwide. The high mortality is directly associated with metastatic disease, which is thought to be initiated by colon cancer stem cells, according to the cancer stem cell (CSC) model. Consequently, early identification of those patients who are at high risk for metastasis is crucial for improved treatment and patient outcomes. Metastasis-associated in colon cancer 1 (MACC1) is a novel prognostic biomarker for tumor progression and metastasis formation independent of tumor stage. We previously showed an involvement of MACC1 in cancer stemness in the mouse intestine of our MACC1 transgenic mouse models. However, the expression of MACC1 in human CSCs and possible implications remain elusive. Here, we explored the molecular mechanisms by which MACC1 regulates stemness and the CSC-associated invasive phenotype based on patient-derived tumor organoids (PDOs), patient-derived xenografts (PDXs) and human CRC cell lines. We showed that CD44-enriched CSCs from PDO models express significantly higher levels of MACC1 and LGR5 and display higher tumorigenicity in immunocompromised mice. Similarly, RNA sequencing performed on PDO and PDX models demonstrated significantly increased MACC1 expression in ALDH1(+) CSCs, highlighting its involvement in cancer stemness. We further showed the correlation of MACC1 with the CSC markers CD44, NANOG and LGR5 in PDO models as well as established cell lines. Additionally, MACC1 increased stem cell gene expression, clonogenicity and sphere formation. Strikingly, we showed that MACC1 binds as a transcription factor to the LGR5 gene promoter, uncovering the long-known CSC marker LGR5 as a novel essential signaling mediator employed by MACC1 to induce CSC-like properties in human CRC patients. Our in vitro findings were further substantiated by a significant positive correlation of MACC1 with LGR5 in CRC cell lines as well as CRC patient tumors. Taken together, this study indicates that the metastasis inducer MACC1 acts as a cancer stem cell-associated marker. Interventional approaches targeting MACC1 would potentially improve further targeted therapies for colorectal cancer patients to eradicate CSCs and prevent cancer recurrence and distant metastasis formation.

A positive feedback between PDIA3P1 and OCT4 promotes the cancer stem cell properties of esophageal squamous cell carcinoma

BackgroundIncreasing evidence has indicated that long non-coding RNAs (lncRNAs) have been proven to regulate esophageal cancer progression. The lncRNA protein disulfide isomerase family A member 3 pseudogene 1 (PDIA3P1) has been shown to promote cancer stem cell properties; however, its mechanism of action remains unclear. In this study, we investigated the regulation of esophageal cancer stem cell properties by the interaction of PDIA3P1 with proteins.MethodsThe GEPIA2 and Gene Expression Omnibus databases were used to analyze gene expression. PDIA3P1 expression in human esophageal squamous cell carcinoma (ESCC) tissues and cell lines was detected by quantitative real-time polymerase chain reaction (qRT-PCR). Loss-of-function experiments were performed to determine the effects of PDIA3P1 on ESCC cell proliferation, migration, and invasion. The sphere formation assay, number of side population cells, and CD271 + /CD44 + cells were detected by flow cytometry to identify the cancer stem cell properties. RNA immunoprecipitation (RIP), RNA pull-down, co-immunoprecipitation (co-IP), dual luciferase reporter, and cleavage under targets and tagmentation (CUT&Tag) assays were performed to elucidate the underlying molecular mechanisms.ResultsPDIA3P1 expression was upregulated in ESCC cell lines and tissues. Functionally, higher PDIA3P1 expression promoted cell proliferation, invasion, and metastasis and inhibited apoptosis in esophageal cancer. Importantly, PDIA3P1 promoted cancer stem cell properties in ESCC. Mechanistically, PDIA3P1 interacted with and stabilized octamer-binding transcription factor 4 (OCT4) by eliminating its ubiquitination by the ubiquitinating enzyme WW domain-containing protein 2 (WWP2). Moreover, as a transcription factor, OCT4 bound to the PDIA3P1 promoter and promoted its transcription.ConclusionsOur research revealed a novel mechanism by which a positive feedback loop exists between PDIA3P1 and OCT4. It also demonstrated that the PDIA3P1-WWP2-OCT4 loop is beneficial for promoting the cancer stem cell properties of ESCC. Owing to this regulatory relationship, the PDIA3P1-WWP2-OCT4-positive feedback loop might be used in the diagnosis and prognosis, as well as in the development of novel therapeutics for esophageal cancer.

DOT1L promotes expression of CD44 through the Wnt/β-catenin signaling pathway in early gastric carcinoma.

To assess telomere silencing 1-like (DOTIL) gene expression within gastric cancer (GC) tissues as well as its function of promoting cancer stem cell (CSC)-mediated epithelial-mesenchymal switching, tissue samples from 8 patients each in 3 stages (normal, low-grade intraepithelial neoplasia (LGIN), as well as early gastric carcinoma (EGC)) were collected for whole-exome sequencing, which revealed differentially expressed genes (DEGs). The DEGs and their prognostic value were verified through TCGA and GTEx analyses. We also verified the role of DOT1L in EGC development. We collected samples from three patients each with LGIN and EGC for single-cell sequencing. We conducted single-cell transcriptomic analysis, DEG analysis, cell‒cell interaction analysis, and pseudotime analysis using R language. Sites and levels of DOT1L, CD44 and DOT1L expression were verified by IF. We found 703 deleterious mutation sites in the LGIN group and 389 deleterious mutation sites in the EGC group. The LGIN as well as EGC categories exhibited increased levels of DOT1L expression compared to the standard category (P<0.05) in TCGA and GTEx. DOT1L also correlated significantly with TMB (P=8.45E-06), MSI (P=0.001), and tumor proliferation index (P=7.17E-09) in the TCGA and GTEx datasets. In single cells, we found that DOT1L promotes CD44 expression via the Wnt/β-catenin signaling pathway and the development for stemness properties within GC. In addition, we found that DOT1L, CD44 and CTNNB1 colocalize and correlate positively. In conclusion, one important CSC regulator in GC, DOT1L may be crucial in coordinating the expression of genes specific to a certain lineage during MSC development.

Wnt/β-catenin Signaling in Lung Cancer: Association with Proliferation, Metastasis, and Therapy Resistance.

The capacity of cancer cells for abnormal growth and metastasis has made it difficult to find a cure for tumor. Both males and females suffer from lung tumors, and physicians still deem them incurable. The initiation and development of lung tumors can be forced by genomic mutations. Wnt is a critical pathway for regulating growth, differentiation and migration. However, its oncogenic function has been observed in lung cancer. Wnt is able to increase the proliferation of lung tumors. The metastasis potential of lung tumors can be accelerated by Wnt/EMT axis. Overexpression of Wnt/β-catenin prevents chemotherapy-mediated cell death in lung tumors. This pathway promotes cancer stem cell features in lung tumors which induce radioresistance. Anti-cancer agents, such as curcumin, are able to inhibit Wnt in lung tumor treatment. Wnt interaction with other factors in lung tumors is essential in controlling biological behavior, and non-coding RNA transcripts are the most well-known ones. It can be concluded from the current study that Wnt is an important regulator of lung tumorigenesis, and the translation of these findings into the clinic is vital.

The CK2/ECE1c Partnership: An Unveiled Pathway to Aggressiveness in Cancer

The endothelin-1 (ET1) peptide has a pathological role in the activation of proliferation, survival and invasiveness pathways in different cancers. ET1’s effects rely on its activation by the endothelin-converting enzyme-1 (ECE1), which is expressed as four isoforms, differing only in their cytoplasmic N-terminuses. We already demonstrated in colorectal cancer, glioblastoma, and preliminarily lung cancer, that the isoform ECE1c heightens aggressiveness by promoting cancer stem cell traits. This is achieved through a non-canonical ET1-independent mechanism of enhancement of ECE1c’s stability upon CK2-dependent phosphorylation at S18 and S20. Here, a K6 residue is presumably responsible for ECE1c ubiquitination as its mutation to R impairs proteasomal degradation. However, how phosphorylation enhances ECE1c’s stability and how this translates into aggressiveness are still open questions. In this brief report, by swapping residues to either phospho-mimetic or phospho-resistant amino acids, we propose that the N-terminus may also be phosphorylated at Y5 and/or T9 by an unknown kinase(s). In addition, N-terminus phosphorylation may lead to a blockage of K6 ubiquitination, increasing ECE1c’s stability and presumably activating the Wnt/β-catenin signaling pathway. Thus, a novel CK2/ECE1c partnership may be emerging to promote aggressiveness and thus become a biomarker of poor prognosis and a potential therapeutic target for several cancers.

Transgelin Promotes Glioblastoma Stem Cell Hypoxic Responses and Maintenance Through p53 Acetylation.

Glioblastoma (GBM) is a lethal cancer characterized by hypervascularity and necrosis associated with hypoxia. Here, it is found that hypoxia preferentially induces the actin-binding protein, Transgelin (TAGLN), in GBM stem cells (GSCs). Mechanistically, TAGLN regulates HIF1α transcription and stabilizes HDAC2 to deacetylate p53 and maintain GSC self-renewal. To translate these findings into preclinical therapeutic paradigm, it is found that sodium valproate (VPA) is a specific inhibitor of TAGLN/HDAC2 function, with augmented efficacy when combined with natural borneol (NB) in vivo. Thus, TAGLN promotes cancer stem cell survival in hypoxia and informs a novel therapeutic paradigm.

Hedgehog signaling and the glioma-associated oncogene in cancer radioresistance.

Tumor radioresistance remains a key clinical challenge. The Hedgehog (HH) signaling pathway and glioma-associated oncogene (GLI) are aberrantly activated in several cancers and are thought to contribute to cancer radioresistance by influencing DNA repair, reactive oxygen species production, apoptosis, autophagy, cancer stem cells, the cell cycle, and the tumor microenvironment. GLI is reported to activate the main DNA repair pathways, to interact with cell cycle regulators like Cyclin D and Cyclin E, to inhibit apoptosis via the activation of B-cell lymphoma-2, Forkhead Box M1, and the MYC proto-oncogene, to upregulate cell stemness related genes (Nanog, POU class 5 homeobox 1, SRY-box transcription factor 2, and the BMI1 proto-oncogene), and to promote cancer stem cell transformation. The inactivation of Patched, the receptor of HH, prevents caspase-mediated apoptosis. This causes some cancer cells to survive while others become cancer stem cells, resulting in cancer recurrence. Combination treatment using HH inhibitors (including GLI inhibitors) and conventional therapies may enhance treatment efficacy. However, the clinical use of HH signaling inhibitors is associated with toxic side effects and drug resistance. Nevertheless, selective HH agonists, which may relieve the adverse effects of inhibitors, have been developed in mouse models. Combination therapy with other pathway inhibitors or immunotherapy may effectively overcome resistance to HH inhibitors. A comprehensive cancer radiotherapy with HH or GLI inhibitor is more likely to enhance cancer treatment efficacy while further studies are still needed to overcome its adverse effects and drug resistance.

CDA Formulations to Fulfill Cancer Moonshot and to Win the War on Cancer

The objective of this study is to call for approval of cell differentiation agent (CDA) formulations as the right cancer drugs to save cancer patients. Moonshot was a presidential project to set a classic record of success attributable to the right approach and war on cancer was another presidential project to set a classic record of failure attributable to the wrong approach. Cancer moonshot was brought up by President Biden to urge health profession to rely on right approaches to save cancer patients. Perpetual replication of cancer cells (CCs) is the most outstanding feature of cancer. Naturally, killing of replicating CCs becomes the top choice of cancer establishments to combat cancer. Killing of CCs is actually a wrong approach of cancer therapy, because cancer is caused by wound unhealing due to the collapse of chemo-surveillance, which is a natural mechanism to ensure perfection of wound healing. Killing of CCs by cytotoxic agents promotes cancer stem cells (CSCs) to proliferate in order to repair the damages created by cytotoxic agents, eventually pushing CSCs to reach a high proportion to become unresponsive to further treatments. Killing of CCs is a wrong approach that causes the failure of cancer solution. To save cancer patients, we have to drastically change past practices. Apparently, wound healing process is the right approach of cancer therapy. Induction of terminal differentiation of PSCs is the most critical mechanism of wound healing, which is achieved by differentiation inducers (DIs) and differentiation helper inducers (DHIs). CDA is a collective term of the preparations consisting of different proportions of DIs and DHIs. Therefore, CDA formulations are the best solution of cancer to fulfill cancer moonshot and to win the war on cancer. CDA formulations display the features as pro-wound healing that can eliminate both CSCs and CCs by inducing these cells to undergo terminal differentiation, and to restore the functionality of chemo-surveillance, which is the creation of the nature to prevent the buildup of cells with abnormal MEs. A perfect cancer drug must have the ability to eliminate both CSCs and CCs, and to restore the functionality of chemo-surveillance. CDA formulations fit the description as perfect cancer drugs to fulfill cancer moonshot and to win the war on cancer.

Targeted Reprogramming of Vitamin B3 Metabolism as a Nanotherapeutic Strategy towards Chemoresistant Cancers.

Cancer-associated fibroblasts (CAFs) promote cancer stem cell (CSC)-mediated chemoresistance and immunosuppressive tumor microenvironment. However, direct depletion of CAFs may increase cancer invasiveness and metastasis. As a generalized strategy against chemoresistant cancers, Gemini-like homotypic targeting nanoparticles (NPs) are designed for two-pronged CAF transformation and cancer cell elimination. The CAF-targeted NPs couple vitamin B3 metabolic reprogramming to epigenetic modulation of secreted pro-stemness and immunosuppressive factors, thereby diminishing CSC and suppressive immune cell populations to enhance cancer cell drug susceptibility and cytotoxic T cell infiltration. In mouse models of breast, liver, pancreatic and colorectal cancers that are resistant to their respective first-line chemotherapeutics, a single dose of hydrogel co-delivering the Gemini-like NPs can rehabilitate chemosensitivity, induce immune activation, and achieve tumor regression. Moreover, it stimulates robust T cell memory for long-term protection against tumor rechallenge. This study thus represents an innovative approach with broad applicability for overcoming cancer chemoresistance.

Pyrroline-5-Carboxylate Reductase-2 Promotes Colorectal Carcinogenesis by Modulating Microtubule-Associated Serine/Threonine Kinase-like/Wnt/β-Catenin Signaling.

Despite significant progress in clinical management, colorectal cancer (CRC) remains the third most common cause of cancer-related deaths. A positive association between PYCR2 (pyrroline-5-carboxylate reductase-2), a terminal enzyme of proline metabolism, and CRC aggressiveness was recently reported. However, how PYCR2 promotes colon carcinogenesis remains ill understood. A comprehensive analysis was performed using publicly available cancer databases and CRC patient cohorts. Proteomics and biochemical evaluations were performed along with genetic manipulations and in vivo tumor growth assays to gain a mechanistic understanding. PYCR2 expression was significantly upregulated in CRC and associated with poor patient survival, specifically among PYCR isoforms (PYCR1, 2, and 3). The genetic inhibition of PYCR2 inhibited the tumorigenic abilities of CRC cells and in vivo tumor growth. Coinciding with these observations was a significant decrease in cellular proline content. PYCR2 overexpression promoted the tumorigenic abilities of CRC cells. Proteomics (LC-MS/MS) analysis further demonstrated that PYCR2 loss of expression in CRC cells inhibits survival and cell cycle pathways. A subsequent biochemical analysis supported the causal role of PYCR2 in regulating CRC cell survival and the cell cycle, potentially by regulating the expression of MASTL, a cell-cycle-regulating protein upregulated in CRC. Further studies revealed that PYCR2 regulates Wnt/β-catenin-signaling in manners dependent on the expression of MASTL and the cancer stem cell niche. PYCR2 promotes MASTL/Wnt/β-catenin signaling that, in turn, promotes cancer stem cell populations and, thus, colon carcinogenesis. Taken together, our data highlight the significance of PYCR2 as a novel therapeutic target for effectively treating aggressive colon cancer.

Unlocking the secrets of cancer stem cells: Immune checkpoint inhibitors face their formidable foes

In this issue of Cell Stem Cell, Beziaud etal.1 show that immunotherapy induces stem-like properties in models of breast cancer. Strikingly, T-cell-derived IFNγ promotes cancer stem cell (CSC) phenotypes, therapy resistance, and metastasis. Targeting BCAT1 downstream offers promise for enhancing immunotherapy outcomes.