Cancer Stem Research Articles

Dauricine attenuates Oct4/sonic hedgehog co-activated stemness and induces reactive oxygen species-mediated mitochondrial apoptosis via AKT/β-catenin signaling in human neuroblastoma and glioblastoma stem-like cells.

Neuroblastoma and glioblastoma are primary malignant tumors of the nervous system, with frequent relapse and limited clinical therapeutic drugs. The failure of their treatment is due to the tumor cells exhibiting cancer stem-like cells (CSLCs) properties. Octamer binding transcription factor 4 (Oct4) is involved in mediating CSLCs, our previous work found that Oct4-driven reprogramming of astrocytes into induced neural stem cells was potentiated with continuous sonic hedgehog (Shh) stimulation. In this study, we aimed to study the importance of Oct4 and Shh combination in the stemness properties induction of neuroblastoma and glioblastoma cells, and evaluate the anti-stemness effect of dauricine (DAU), a natural product of bis-benzylisoquinoline alkaloid. The effect of Oct4 and Shh co-activation on cancer stemness was evaluated by tumor spheres formation model and flow cytometry analysis. Then the effects of DAU on SH-SY5Y and T98-G cells were assessed by the MTT, colony formation, and tumor spheres formation model. DAU acts on Oct4 were verified using the Western blotting, MTT, and so on. Mechanistic studies were explored by siRNA transfection assay, Western blotting, and flow cytometry analysis. We identified that Shh effectively improved Oct4-mediated generation of stemness in SH-SY5Y and T98-G cells, and Oct4 and Shh co-activation promoted cell growth, the resistance of apoptosis. In addition, DAU, a natural product, was found to be able to attenuate Oct4/Shh co-activated stemness and induce cell cycle arrest and apoptosis via blocking AKT/β-catenin signaling in neuroblastoma and glioblastoma, which contributed to the neuroblastoma and glioblastoma cells growth inhibition by DAU. In summary, our results indicated that the treatment of DAU may be served as a potential therapeutic method in neuroblastoma and glioblastoma.

Androgen receptor promotes cell stemness via interacting with co-factor YAP1 in gastric cancer

Cancer stem cells (CSCs) have been proposed to explain tumor relapse and chemoresistance in various types of cancers, and androgen receptor (AR) has been emerged as a potential regulator of stemness in cancers. However, the underlying mechanism of AR-regulated CSCs properties and chemoresistance in gastric cancer (GC) remains unknown. Here, we shown that AR is upregulated in GC tissues and correlates with poor survival rate and CSCs phenotypes of GC patients. According to our experimental data, overexpression of AR upregulated the expression of CSCs markers and this was consistent with the result concluded from data analysis that the expression of AR was positively correlated with CD44 in GC patients. In addition, AR overexpression obviously enhanced the tumor sphere formation ability and chemoresistance of GC cells in vitro. Whereas these effects were attenuated by inhibition of AR. These results were further validated in vivo that MGC-803 cells overexpressing AR had stronger properties to initiate gastric tumorigenesis than the control cells, and inhibition of AR increased the chemosensitivity of GC cells. Mechanically, AR upregulated CD44 expression by directly binding to its promoter region and Yes-associated protein 1 (YAP1) served as the co-factor of AR, which was demonstrated by the fact that the promoting effects of AR on GC cells stemness were partially counteracted by YAP1 knockdown. Thus, this study revealed that AR facilitates CSCs properties and chemoresistance of GC cells via forming complex with YAP1and indicates a potential therapeutic approach to GC patients.

B-373 The Development of a Logic-Gate Probe to Investigate Hypoxia in Cancer Stem Cells

Abstract Background Cancer stem cells (CSCs) represent only a small fraction of the tumor population, yet they present a profound challenge to cancer treatment. CSCs contribute to tumor complexity via their unique ability to self-renew, develop into multiple lineages, and maintain an unchecked proliferation potential. To identify CSCs, the cytoprotective enzyme aldehyde dehydrogenase 1A1 (ALDH1A1) is a well-annotated biomarker of cancer stemness which is associated with a poor prognosis in patients with gastric and lung cancers when overexpressed. Within CSCs, ALDH1A1 functions to regulate oxidative stress by transforming biological aldehydes into their corresponding non-toxic carboxylic acid counterparts and further is linked to the retinaldehyde signaling pathway. Beyond this enzyme, oxygen availability within the tumor microenvironment (TME) can also influence stemness properties. Specifically, hypoxia, is required to maintain the CSC phenotype by prolonging the undifferentiated state. Methods To study the mechanistic underpinnings of complex relationship in vivo new technologies are needed as current approaches are insufficient. Indeed, probes have been developed to study ALDH1A1 and hypoxia in parallel, however, imaging approaches lack the requisite resolution to ensure they are reporting on the same CSC population. To this end, we have designed a powerful logic-gate probe that links the reporters of ALDH1A1 activity and oxygenation in a unique manner such that different readouts will result (color of light) depending on the TME environment. Results Our lab has previously developed a near-infrared hypoxia-sensing fluorescent probe that is fundamental to our current logic-gate design. This component has been validated in 4T1 murine breast cancer cells, to yield a 1.6-fold increase in ratiometric fluorescence response when incubated under hypoxic conditions as compared to its normoxic controls. Additionally, the ALDH1A1 sensing component has been validated via purified enzyme to yield an increase in bioluminescent signal enabling its use for future in vivo studies. Conclusion This technology has important clinical implications to understand the mechanistic underpinnings between oxygenation and cancer stemness. Further research is being conducted to further test the hypothesis that metformin (anticancer drug) kills cancer by altering oxygen metabolism which in turn depletes the CSC population. Furthermore, this probe has far-reaching implications in monitoring novel therapeutic cancer treatment.

Knockdown of BAP31 Downregulates Galectin-3 to Inhibit the Wnt/β-Catenin Signaling Pathway to Modulate 5-FU Chemosensitivity and Cancer Stemness in Colorectal Cancer.

Increased stemness is causally linked to the development of chemoresistance in cancers. B-cell receptor-associated protein 31 (BAP31) has been identified to play an oncogenic role in many types of cancer. However, the role of BAP31 in 5-fluorouracil (5-FU) chemosensitivity and stemness of colorectal cancer (CRC) is still unknown. The aim of this study was to investigate the biological function and molecular mechanism of BAP31 in regulating 5-FU chemosensitivity and stemness. The correlation between BAP31 expression and 5-FU chemosensitivity was examined using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide and colony formation assays. Cancer stemness was analyzed using tumor sphere formation and Western blot assays. Western blot and immunofluorescence analyses of the knockdown cell lines were performed to explore the possible mechanisms. Finally, we investigated the function of BAP31 by constructing xenograft nude mouse models in vivo. In this study, we demonstrated that BAP31 was increased in CRC cells, and knockdown of BAP31 reduced the half maximal inhibitory concentration (IC50) of 5-FU, while this effect was reversed by overexpression of BAP31. In addition, knockdown of BAP31 substantially reduced the stemness of CRC cells in vitro. Consistently, knockdown of BAP31 significantly suppressed the tumorigenicity and stemness of CRC in vivo. The functional study further suggested that knockdown of BAP31 downregulated galectin-3 to inhibit the accumulation of β-catenin, which in turn repressed the transcription of downstream target genes (c-MYC, SOX2) of the Wnt/β-catenin signaling pathway. Knockdown of BAP31 reduced stemness by inhibiting the Wnt/β-catenin signaling pathway to increase 5-FU chemosensitivity. Importantly, intrabodies against BAP31 suppressed tumor growth and enhanced the antitumor effects of 5-FU in vivo. Therefore, using intrabodies against BAP31 may be a strategy for improving the antitumor effect of 5-FU in CRC.

Pan cancer characterization of genes whose expression has been associated with LINE-1 antisense promoter activity

BackgroundLong interspersed nuclear element-1 (LINE-1 or L1) comprises 17% of the human genome. As the only autonomous and active retrotransposons, L1 may take part in cancer initiation and progression in some ways. The studies of L1 in cancer mainly focus on the impact of L1 insertion into the new genome locus. The L1 5´ untranslated region (UTR) also contains antisense promoter (ASP) activity, generating L1-gene chimeric transcripts to a neighbor exon. Some of these ASP-associated genes have been reported to be overexpressed in cancer and promote cancer cell growth. However, little is known about overall expression patterns and the roles of L1 ASP-associated genes in human cancers.ResultsL1 ASP-associated genes were frequently dysregulated in cancer and associated with the cell cycle, the PI3K/AKT pathway, and the GTPase signaling pathway. The expression of L1 ASP-associated genes was correlated with tumor patient prognosis. Hub L1 ASP-associated genes CENPU and MCM2 showed a correlation with immune infiltration, clinical T stage, and cancer stemness in pan-cancer. Knockdown of L1 ASP-associated gene LINC00491 resulted in a significant decrease in tumor growth and migration ability.ConclusionsThe expression of L1 ASP-associated genes is significantly dysregulated at the pan-cancer level, which is closely related to the tumor microenvironment, progression, and patient prognosis. Hub genes CENPU and MCM2 are expected to be new tumor diagnostic markers and therapeutic targets.

P09-31: Fludioxonil enhanced the development of the multinucleate-giant cancer cells related to cancer metastasis, chemo-resistance, and cancer stemness as an endocrine-disrupting chemical in triple-negative breast cancer cells

P09-31: Fludioxonil enhanced the development of the multinucleate-giant cancer cells related to cancer metastasis, chemo-resistance, and cancer stemness as an endocrine-disrupting chemical in triple-negative breast cancer cells

Exploration of NPC2 as a Potential Biomarker for Immunotherapy Using RNA-seq and Protein Data - A New Hypothesis.

NPC2 is well known as a player for cholesterol transport. However, the biological role of NPC2 in cancer development and therapy is far from clear. Here, we explore the potential role of NPC2 in prognosis and immunotherapy across multiple cancer types by integrating RNA-seq data from TCGA and GTEx, protein data from CPTAC, and multiple web analysis databases. Expression depiction between tumour and normal tissues indicated that NPC2 is overexpressed in the majority of the most common cancer types, including glioblastoma and pancreatic cancer, two cancers mostly difficult to diagnose and treat. Cancer stemness in glioblastoma is negatively associated with NPC2 level. NPC2 expression is positively correlated with immune cell infiltration and the expression of several immune checkpoints. IDH1 mutation in GBM is negatively correlated with NPC2 level, while a positive correlation has been found between TP53 mutation and NPC2 expression in pancreatic cancer. NPC2 is also correlated with levels of serum biomarkers used for diagnosis of pancreatic cancer.

Machine learning-based integration develops a metabolism-derived consensus model for improving immunotherapy in pancreatic cancer

BackgroundPancreatic cancer (PAC) is one of the most malignant cancer types and immunotherapy has emerged as a promising treatment option. PAC cells undergo metabolic reprogramming, which is thought to modulate...

Vimentin promotes glioma progression and maintains glioma cell resistance to oxidative phosphorylation inhibition.

Glioma has been demonstrated as one of the most malignant intracranial tumors and currently there is no effective treatment. Based on our previous RNA-sequencing data for oxidative phosphorylation (OXPHOS)-inhibition resistant and OXPHOS-inhibition sensitive cancer cells, we found that vimentin (VIM) is highly expressed in the OXPHOS-inhibition resistant cancer cells, especially in glioma cancer cells. Further study of VIM in the literature indicates that it plays important roles in cancer progression, immunotherapy suppression, cancer stemness and drug resistance. However, its role in glioma remains elusive. This study aims to decipher the role of VIM in glioma, especially its role in OXPHOS-inhibition sensitivity, which may provide a promising therapeutic target for glioma treatment. The expression of VIM in glioma and the normal tissue has been obtained from The Cancer Genome Atlas (TCGA) database, and further validated in Human Protein Atlas (HPA) and Chinese Glioma Genome Atlas (CGGA). And the single-cell sequencing data was obtained from TISCH2. The immune infiltration was calculated via Tumor Immune Estimation Resource (TIMER), Estimation of Stromal and Immune Cells in Malignant Tumors using Expression Data (ESTIMATE) and ssGSEA, and the Immunophenoscore (IPS) was calculated via R package. The differentiated expressed genes were analyzed including GO/KEGG and Gene Set Enrichment Analysis (GSEA) between the VIM-high and -low groups. The methylation of VIM was checked at the EWAS and Methsurv. The correlation between VIM expression and cancer stemness was obtained from SangerBox. We also employed DepMap data and verified the role of VIM by knocking down it in VIM-high glioma cell and over-expressing it in VIM-low glioma cells to check the cell viability. Vim is highly expressed in the glioma patients compared to normal samples and its high expression negatively correlates with patients' survival. The DNA methylation in VIM promoters in glioma patients is lower than that in the normal samples. High VIM expression positively correlates with the immune infiltration and tumor progression. Furthermore, Vim is expressed high in the OXPHOS-inhibition glioma cancer cells and low in the OXPHOS-inhibition sensitive ones and its expression maintains the OXPHOS-inhibition resistance. In conclusion, we comprehensively deciphered the role of VIM in the progression of glioma and its clinical outcomes. Thus provide new insights into targeting VIM in glioma cancer immunotherapy in combination with the current treatment.

Downregulation of microRNA-326 enhances ZNF322A expression, transcriptional activity and tumorigenic effects in lung cancer.

Zinc finger protein ZNF322A is an oncogenic transcription factor. Overexpression of ZNF322A activates pro-metastasis, cancer stemness, and neo-angiogenesis-related genes to enhance lung cancer progression. However, the upstream regulator of ZNF322A is not well defined. Dysregulation of microRNAs (miRNAs) can mediate cancer cell growth, migration, and invasion to promote tumorigenesis. Here, we uncover the mechanism of miRNA-mediated transcriptional regulation in ZNF322A-driven oncogenic events. ZNF322A harbors several putative miRNA-binding sites in the 3'-untranslated region (UTR). We validated that miR-326 downregulated ZNF322A-3'-UTR luciferase activity and mRNA expression. Furthermore, miR-326 suppressed the expression of ZNF322A-driven cancer-associated genes such as cyclin D1 and alpha-adducin. Reconstitution experiments by ectopic overexpression of ZNF322A abolished miR-326-suppressed cancer cell proliferation and cell migration capacity. Moreover, miR-326 attenuated ZNF322A-induced tumor growth and lung tumor metastasis in vivo. Clinically, the expression of miR-326 negatively correlated with ZNF322A mRNA expression in surgically resected tissues from 120 non-small cell lung cancer (NSCLC) patients. Multivariate Cox regression analysis demonstrated that NSCLC patients with low miR-326/high ZNF322A profile showed poor overall survival. Our results reveal that the deregulated expression of miR-326 leads to hyperactivation of ZNF322A-driven oncogenic signaling. Targeting the miR-326/ZNF322A axis would provide new therapeutic strategies for lung cancer patients.

Promoter hypermethylation of neural-related genes is compatible with stemness in solid cancers

BackgroundDNA hypermethylation is an epigenetic feature that modulates gene expression, and its deregulation is observed in cancer. Previously, we identified a neural-related DNA hypermethylation fingerprint in colon cancer, where most of the top hypermethylated and downregulated genes have known functions in the nervous system. To evaluate the presence of this signature and its relevance to carcinogenesis in general, we considered 16 solid cancer types available in The Cancer Genome Atlas (TCGA).ResultsAll tested cancers showed significant enrichment for neural-related genes amongst hypermethylated genes. This signature was already present in two premalignant tissue types and could not be explained by potential confounders such as bivalency status or tumor purity. Further characterization of the neural-related DNA hypermethylation signature in colon cancer showed particular enrichment for genes that are overexpressed during neural differentiation. Lastly, an analysis of upstream regulators identified RE1-Silencing Transcription factor (REST) as a potential mediator of this DNA methylation signature.ConclusionOur study confirms the presence of a neural-related DNA hypermethylation fingerprint in various cancers, of genes linked to neural differentiation, and points to REST as a possible regulator of this mechanism. We propose that this fingerprint indicates an involvement of DNA hypermethylation in the preservation of neural stemness in cancer cells.

TRIM21 promotes tumor progression and cancer stemness in cervical squamous cell carcinoma

BackgroundThe ubiquitin ligase family member triplex motif protein 21 (TRIM21), which is involved in the proliferation, metastasis, and selective death of tumor cells, is crucial in the ubiquitination of a number of tumor marker proteins. As research progresses, more studies demonstrate that TRIM21 expression levels can be used to predict cancer prognosis. However, it is unclear how exactly TRIM21 contributes to cervical squamous carcinoma. MethodsImmunohistochemistry, Western Blot, and q-PCR were utilized to determine the expression level of TRIM21 in 113 patients with CESC removed by stage I surgery at Xijing Hospital from 2018 to 2023 using paraffin-embedded tumor tissues and 12 pairs of fresh tumor tissues and their paracancerous tissues. Log-rank analysis using SPSS 23.0 was performed for prognosis and survival analysis using univariate/multifactorial analysis. CCK-8, wound-healing and Scratch assay verified that TRIM21 promoted cell proliferation, migration and invasion. The effect of overexpression and knockdown of TRIM21 on tumor stemness was examined using sphere-forming assay and Western Blot. Finally, we constructed a xenograft model to observe the effect of TRIM21 on tumorigenesis in Si Ha cell lines in vivo. ResultsTRIM21 expression is greater in CESC tissues than in paracancerous tissues, according to immunohistochemical data. Similarly, at the protein and mRNA levels, we verified this conclusion using Western-Blotting and q-PCR. Prognostic and OS analysis showed that TRIM21 expression levels are associated with individual prognostic factors. CCK-8, Wound healing, Transwell, and Sphere-forming tests all demonstrated that TRIM21 overexpression enhances Ca Ski cell proliferation, migration, invasion, and stemness. TRIM21 knockdown in Si Ha inhibited tumor cell proliferation, migration, invasion, and stemness. The experimental results of xenograft models demonstrated that TRIM21 knockdown in Si Ha cells inhibited tumor development. ConclusionTRIM21 is a poor predictor of prognosis for cervical squamous cell carcinoma and might open up new avenues for investigation into therapeutic targets.

Selenium modulates AR/IGF-1R/EGFR and TROP2 signaling pathways and improves anticancer efficacy in murine mammary carcinoma 4T1

The micronutrient selenium (Se) has been shown to exert potential anticancer properties. This study aimed to evaluate the effects of Se (in Se yeast form) on the selenoproteins (SELENO), AR/IGF-1R/EGFR, PI3K/Akt/mTOR and Ras/Raf/ERK cascades, and immune checkpoint blockade in TNBC murine 4T1 cells. We also assessed the effects of combination treatment with chemotherapeutic doxorubicin and Se on trophoblast cell surface antigen 2 (TROP2) levels. Compared with the control groups, cells incubated with Se (0.25, 0.5, 0.75, 1.0, 1.5 µg Se/mL) have lower viability, raised intracellular Se concentrations and SELENO expression, and higher malondialdehyde products in a dose-dependent manner. Se induced the inactivation of AR/IGF-1R/EGFR and downregulation of the PI3K/Akt/mTOR and Ras/Raf/ERK signaling molecules. Se-treated cells also exhibited decreased mitochondrial membrane potential, reduced levels of the cell cycle regulatory protein cyclin D1, cancer stemness, metastatic and EMT-related markers, and increased apoptosis. Subsequently, Se treatment significantly suppressed PD-1/PD-L1 and CTLA-4 mRNA levels and proteins. Doxorubicin decreased 4T1 cell viability and TROP2 expression levels, but the addition of Se to doxorubicin contributed to further reductions. Similar responses to Se treatment were also observed in the human MDA-MB-231 and MCF-7 breast cancer cells. These results show that Se upregulates SELENO and anti-AR/IGF-1R/EGFR signaling in TNBC cells, thus inducing oxidative stress-dependent apoptosis and cell cycle arrest, stemness, EMT, and metastasis, as well as blocking the immune checkpoint molecules. TROP2 down-regulation with Se is also a potential anti-TNBC therapeutic target.

Exploring the glycolytic cross-talk genes between inflammatory bowel disease and colorectal cancer

Patients with inflammatory bowel disease (IBD) have a higher risk of developing colorectal cancer (CRC). Glycolysis is involved in the development of both IBD and CRC. However, the mechanisms and outcomes of glycolysis shared between IBD and CRC remain unclear. This study aimed to explore the glycolytic cross-talk genes between IBD and CRC integrating bioinformatics and machine learning. With WGCNA, LASSO, COX, and SVM-RFE algorithms, P4HA1 and PMM2 were identified as glycolytic cross-talk genes. The independent risk signature of P4HA1 and PMM2 was constructed to predict the overall survival rate of patients with CRC. The risk signature correlated with clinical characteristics, prognosis, tumor microenvironment, immune checkpoint, mutants, cancer stemness, and chemotherapeutic drug sensitivity. CRC patients with high risk have increased microsatellite instability, tumor mutation burden. The nomogram integrating risk score, tumor stage, and age showed high accuracy for predicting overall survival rate. In addition, the diagnostic model for IBD based on P4HA1 and PMM2 showed excellent accuracy. Finally, immunohistochemistry results showed that P4HA1 and PMM2 were significantly upregulated in IBD and CRC. Our study reveals the presence of glycolytic cross-talk genes P4HA1 and PMM2 between IBD and CRC. This may prove to be beneficial in advancing research on the mechanism of development of IBD-associated CRC.

LINC00853 contributes to tumor stemness of gastric cancer through FOXP3-mediated transcription of PDZK1IP1

BackgroundThe incidence and mortality of gastric cancer (GC) are high worldwide. Tumor stemness is a major contributor to tumorigenesis and development of GC, in which long non-coding RNAs (lncRNAs) are deeply involved. The purpose of this study was to investigate the influences and mechanisms of LINC00853 in the progression and stemness of GC.MethodsThe level of LINC00853 was assessed based on The Cancer Genome Atlas (TCGA) database and GC cell lines by RT-PCR and in situ hybridization. An evaluation of biological functions of LINC00853 including cell proliferation, migration, and tumor stemness was conducted via gain-and loss-of-function experiments. Furthermore, RNA pull-down and RNA immunoprecipitation (RIP) assay were utilized to validate the connection between LINC00853 and the transcription factor Forkhead Box P3 (FOXP3). Nude mouse xenograft model was used to identify the impacts of LINC00853 on tumor development.ResultsWe identified the up-regulated levels of lncRNA-LINC00853 in GC, and its overexpression correlates with poor prognosis in GC patients. Further study indicated that LINC00853 promoted cell proliferation, migration and cancer stemness while suppressed cell apoptosis. Mechanistically, LINC00853 directly bind to FOXP3 and promoted FOXP3-mediated transcription of PDZK1 interacting protein 1(PDZK1IP1). Alterations of FOXP3 or PDZK1IP1 reversed the LINC00853-induced biological effects on cell proliferation, migration and stemness. Moreover, xenograft tumor assay was used to investigate the function of LINC00853 in vivo.ConclusionsTaken together, these findings revealed the tumor-promoting activity of LINC00853 in GC, expanding our understanding of lncRNAs regulation on GC pathogenesis.

Prolyl 4-hydroxylase P4HA1 Mediates the Interplay Between Glucose Metabolism and Stemness in Pancreatic Cancer Cells.

Cancer stem cells (CSCs) are profoundly implicated in tumor initiation and progression as well as drug resistance and tumor recurrence of many cancer types, especially pancreatic ductal adenocarcinoma (PDAC). Previously, we revealed that prolyl 4-hydroxylase subunit alpha 1 (P4HA1) enhances the Warburg effect and tumor growth in PDAC. However, the possible connection between P4HA1 and cancer stemness in PDAC remains obscure. In this study, P4HA1-dependent cancer stemness was studied by sphere-formation assay and detection of stemness markers. Glycolytic capacity in cancer stem cells and their parental tumor cells was investigated by glucose uptake, lactate secretion, and expression of glycolytic genes. Glycolysis inhibitors were used to determine the link between cancer stemness and glycolysis. A subcutaneous xenograft model was generated to investigate P4HA1-induced stemness and glycolysis in vivo. We revealed that ectopic expression of P4HA1 increased the stemness of PDAC cells as evidenced by the increased proportion of CD133+ cells, elevated sphere-formation ability, and the upregulated levels of cancer stemness-related proteins (SOX2, OCT4, and NANOG). Blocking tumor glycolysis with 2-Deoxy-D-glucose (2-DG) or a selective inhibitor of glucose transporter 1 (STF-31) significantly reduced the stem properties of PDAC cells, suggesting that P4HA1-induced glycolysis was essential for the stem-like phenotype of PDAC cells. In addition, in vivo study reaffirmed a promotive effect of P4HA1 on tumor glycolysis and cancer stemness. Collectively, our findings suggest that P4HA1 not only affects tumor metabolic reprogramming but also facilitates cancer stemness, which might be exploited as a vulnerable target for PDAC treatment.

First report of the occurrence of Pestalotiopsis sp. on blueberry in Bulgaria – morphology and pathogenicity - (short communication)

The cultivation of blueberry (Vaccinium sp.) in Bulgaria has increased in recent years, but the knowledge of its diseases is almost nonexistent. During monitoring for the sanitary status of blueberry crops in Southern Bulgaria (Plovdiv region), symptoms of stem cancer, twigs necrotic lesions, leaf spots and low vigour were observed on 3-year-old Duke cv. Four isolates were obtained from damaged stems and leaves and were single-spored. The isolates were recognized as Pestalotiopsis sp. according to the cultural characteristics of the fungal colony (colony color and the presence of fruiting bodies) and morphological characteristics of conidia (color, length, width, number and size of the apical and basal appendages). In a controlled experiment, the representative isolate was pathogenic to the Duke cv. Based on morphological characteristics and pathogenicity, this study is the first report of the Pestalotiopsis sp. associated with cancer stem and leaf spots on blueberries in Bulgaria.

GSK3β-driven SOX2 overexpression is a targetable vulnerability in esophageal squamous cell carcinoma.

Esophageal squamous cell carcinoma (ESCC) is one of the deadliest forms of human malignancy that currently lacks approved targeted therapeutics. Accumulating evidence suggests that SOX2 overexpression is a key driving factor for ESCC and various squamous cell carcinoma. Here, through screening a small-molecule kinase inhibitor library, we identified GSK3β as a kinase that is critically required for robust SOX2 expression in ESCC cells. GSK3β did not promote SOX2 transcriptionally but was required for SOX2 protein stability. We demonstrated that GSK3β interacts with and phosphorylates SOX2 at residue S251, which blocks SOX2 from ubiquitination and proteasome-dependent degradation instigated by ubiquitin E3 ligase CUL4ADET1-COP1. Pharmacological inhibition or knockdown of GSK3β by RNA interference selectively impaired SOX2-positive ESCC cell proliferation, cancer stemness, and tumor growth in mouse xenograft model, suggesting that GSK3β promotes ESCC tumorigenesis primarily by driving SOX2 overexpression. GSK3β was found to be frequently overexpressed in clinical esophageal tumors, and there was a positive correlation between GSK3β and SOX2 protein levels. Notably, we found that SOX2 enhanced GSK3β expression transcriptionally, suggesting the existence of a vicious cycle that drives a coordinated GSK3β and SOX2 overexpression in ESCC cells. Finally, we demonstrated in tumor xenograft model that GSK3β inhibitor AR-A014418 was effective in suppressing SOX2-positive ESCC tumor progression and inhibited tumor progression cooperatively with chemotherapeutic agent carboplatin. In conclusion, we uncovered a novel role for GSK3β in driving SOX2 overexpression and tumorigenesis and provided evidence that targeting GSK3β may hold promise for the treatment of recalcitrant ESCCs.

Cross-talk of RNA modification "writers" describes tumor stemness and microenvironment and guides personalized immunotherapy for gastric cancer.

RNA modifications, TME, and cancer stemness play significant roles in tumor development and immunotherapy. The study investigated cross-talk and RNA modification roles in the TME, cancer stemness, and immunotherapy of gastric cancer (GC). We applied an unsupervised clustering method to distinguish RNA modification patterns in GC. GSVA and ssGSEA algorithms were applied. The WM_Score model was constructed for evaluating the RNA modification-related subtypes. Also, we conducted an association analysis between the WM_Score and biological and clinical features in GC and explored the WM_Score model's predictive value in immunotherapy. We identified four RNA modification patterns with diverse survival and TME features. One pattern consistent with the immune-inflamed tumor phenotype showed a better prognosis. Patients in WM_Score high group were related to adverse clinical outcomes, immune suppression, stromal activation, and enhanced cancer stemness, while WM_Score low group showed opposite results. The WM_Score was correlated with genetic, epigenetic alterations, and post-transcriptional modifications in GC. Low WM_Score was related to enhanced efficacy of anti-PD-1/L1 immunotherapy. We revealed the cross-talk of four RNA modification types and their functions in GC, providing a scoring system for GC prognosis and personalized immunotherapy predictions.

PCTAIRE Protein Kinase 1 (PCTK1) Suppresses Proliferation, Stemness, and Chemoresistance in Colorectal Cancer through the BMPR1B-Smad1/5/8 Signaling Pathway.

Colorectal cancer (CRC) is the third most common cancer and a leading cause of cancer-related mortality worldwide. Even with advances in therapy, CRC mortality remains high. Therefore, there is an urgent need to develop effective therapeutics for CRC. PCTAIRE protein kinase 1 (PCTK1) is an atypical member of the cyclin-dependent kinase (CDK) family, and the function of PCTK1 in CRC is poorly understood. In this study, we found that patients with elevated PCTK1 levels had a better overall survival rate in CRC based on the TCGA dataset. Functional analysis also showed that PCTK1 suppressed cancer stemness and cell proliferation by using PCTK1 knockdown (PCTK1-KD) or knockout (PCTK1-KO) and PCTK1 overexpression (PCTK1-over) CRC cell lines. Furthermore, overexpression of PCTK1 decreased xenograft tumor growth and knockout of PCTK1 significantly increased in vivo tumor growth. Moreover, knockout of PCTK1 was observed to increase the resistance of CRC cells to both irinotecan (CPT-11) alone and in combination with 5-fluorouracil (5-FU). Additionally, the fold change of the anti-apoptotic molecules (Bcl-2 and Bcl-xL) and the proapoptotic molecules (Bax, c-PARP, p53, and c-caspase3) was reflected in the chemoresistance of PCTK1-KO CRC cells. PCTK1 signaling in the regulation of cancer progression and chemoresponse was analyzed using RNA sequencing and gene set enrichment analysis (GSEA). Furthermore, PCTK1 and Bone Morphogenetic Protein Receptor Type 1B (BMPR1B) in CRC tumors were negatively correlated in CRC patients from the Timer2.0 and cBioPortal database. We also found that BMPR1B was negatively correlated with PCTK1 in CRC cells, and BMPR1B expression was upregulated in PCTK1-KO cells and xenograft tumor tissues. Finally, BMPR1B-KD partially reversed cell proliferation, cancer stemness, and chemoresistance in PCTK1-KO cells. Moreover, the nuclear translocation of Smad1/5/8, a downstream molecule of BMPR1B, was increased in PCTK1-KO cells. Pharmacological inhibition of Smad1/5/8 also suppressed the malignant progression of CRC. Taken together, our results indicated that PCTK1 suppresses proliferation and cancer stemness and increases the chemoresponse of CRC through the BMPR1B-Smad1/5/8 signaling pathway.