Hypoxic tumor-derived exosomal miR-4488 induces macrophage M2 polarization to promote liver metastasis of pancreatic neuroendocrine neoplasm through RTN3/FABP5 mediated fatty acid oxidation.

Tumor-associated macrophages (TAMs) represent a predominant cellular component within the tumor microenvironment (TME) of pancreatic neuroendocrine neoplasms (pNENs). There is a growing body of evidence highlighting the critical role of exosomes in facilitating communication between tumor cells and TAMs, thereby contributing to the establishment of the premetastatic niche. Nonetheless, the specific mechanisms through which exosomes derived from tumor cells influence macrophage polarization under hypoxic conditions in pNENs, and the manner in which these interactions support cancer metastasis, remain largely unexplored. Recognizing the capacity of exosomes to transfer miRNAs that can modify cellular behaviors, our research identified a significant overexpression of miR-4488 in exosomes derived from hypoxic pNEN cells. Furthermore, we observed that macrophages that absorbed circulating exosomal miR-4488 underwent M2-like polarization. Our investigations revealed that miR-4488 promotes M2-like polarization by directly targeting and suppressing RTN3 in macrophages. This suppression of RTN3 enhances fatty acid oxidation and activates the PI3K/AKT/mTOR signaling pathway through the interaction and downregulation of FABP5. Additionally, M2 polarized macrophages contribute to the formation of the premetastatic niche and advance pNENs metastasis by releasing MMP2, thereby establishing a positive feedback loop involving miR-4488, RTN3, FABP5, and MMP2 in pNEN cells. Together, these findings shed light on the role of exosomal miRNAs from hypoxic pNEN cells in mediating interactions between pNEN cells and intrahepatic macrophages, suggesting that miR-4488 holds potential as a valuable biomarker and therapeutic target for pNENs.

Hypoxia exosome derived CEACAM5 promotes tumor-associated macrophages M2 polarization to accelerate pancreatic neuroendocrine tumors metastasis via MMP9.

Exosomes play significant roles in the communications between tumor cells and tumor microenvironment. However, the specific mechanisms by which exosomes modulate tumor development under hypoxia in pancreatic neuroendocrine tumors (pNETs) are not well understood. This study aims to investigate these mechanisms and made several important discoveries. We found that hypoxic exosomes derived from pNETs cells can activate tumor-associated macrophages (TAM) to the M2 phenotype, in turn, the M2-polarized TAM, facilitate the migration and invasion of pNETs cells. Further investigation revealed that CEACAM5, a protein highly expressed in hypoxic pNETs cells, is enriched in hypoxic pNETs cell-derived exosomes. Hypoxic exosomal CEACAM5 was observed to induce M2 polarization of TAM through activation of the MAPK signaling pathway. Coculturing pNETs cells with TAM or treated with hypoxic exosomes enhanced the metastatic capacity of pNETs cells. In conclusion, these findings suggest that pNETs cells generate CEACAM5-rich exosomes in a hypoxic microenvironment, which in turn polarize TAM promote malignant invasion of pNETs cells. Targeting exosomal CEACAM5 could potentially serve as a diagnostic and therapeutic strategy for pNETs.

Identification of EGR4 as a prospective target for inhibiting tumor cell proliferation and a novel biomarker in colorectal cancer.

EGR4 (Early Growth Response 4) is a member of the EGR family, involving in tumorigenesis. However, the function and action mechanism of EGR4 in the pathogenesis of colorectal cancer (CRC) remain unclear. To address this, we assessed the prognosis of CRC based on EGR4 using the Kaplan-Meier plotter tool and tissue microarray. The abundance of immunoinfiltration was evaluated through ssGSEA, TISIDB, and TIMER. In vitro experiments involving knockdown or overexpression of EGR4 were performed, and RNA-sequencing was conducted to explore potential mechanisms. Furthermore, we used oxaliplatin and 5-fluorouracil to validate the impact of EGR4 on chemo-resistance. Pan-cancer analysis and tissue microarray showed that EGR4 was highly expressed in CRC and significantly correlated with an unfavorable prognosis. Moreover, EGR4 expression was associated with immunoinfiltration and cancer-associated fibroblasts in the CRC microenvironment. Functional enrichment demonstrated that high-expressional EGR4 were involved in chromatin and nucleosome assembly. Additionally, EGR4 promoted the proliferation of CRC cells. Mechanistically, EGR4 upregulated TNFα to activate the NF-κB signaling pathway, and its knockdown reduced p65 nuclear translocation. Importantly, combining shEGR4 with oxaliplatin and 5-fluorouracil significantly inhibited CRC proliferation. Taken together, these findings provide new insights into the potential prognosis and therapeutic targets of EGR4 in CRC.

Hypoxia upregulating ACSS2 enhances lipid metabolism reprogramming through HMGCS1 mediated PI3K/AKT/mTOR pathway to promote the progression of pancreatic neuroendocrine neoplasms.

BACKGROUND: Pancreatic neuroendocrine neoplasms (pNENs) are relatively rare. Hypoxia and lipid metabolism-related gene acetyl-CoA synthetase 2 (ACSS2) is involved in tumor progression, but its role in pNENs is not revealed. This study showed that hypoxia can upregulate ACSS2, which plays an important role in the occurrence and development of pNENs through lipid metabolism reprogramming. However, the precise role and mechanisms of ACSS2 in pNENs remain unknown. METHODS: mRNA and protein levels of ACSS2 and 3-hydroxy-3-methylglutaryl-CoA synthase1 (HMGCS1) were detected using quantitative real-time PCR (qRT-PCR) and Western blotting (WB). The effects of ACSS2 and HMGCS1 on cell proliferation were examined using CCK-8, colony formation assay and EdU assay, and their effects on cell migration and invasion were examined using transwell assay. The interaction between ACSS2 and HMGCS1 was verified by Co-immunoprecipitation (Co-IP) experiments, and the functions of ACSS2 and HMGCS1 in vivo were determined by nude mouse xenografts. RESULTS: We demonstrated that hypoxia can upregulate ACSS2 while hypoxia also promoted the progression of pNENs. ACSS2 was significantly upregulated in pNENs, and overexpression of ACSS2 promoted the progression of pNENs and knockdown of ACSS2 and ACSS2 inhibitor (ACSS2i) treatment inhibited the progression of pNENs. ACSS2 regulated lipid reprogramming and the PI3K/AKT/mTOR pathway in pNENs, and ACSS2 regulated lipid metabolism reprogramming through the PI3K/AKT/mTOR pathway. Co-IP experiments indicated that HMGCS1 interacted with ACSS2 in pNENs. Overexpression of HMGCS1 can reverse the enhanced lipid metabolism reprogramming and tumor-promoting effects of knockdown of ACSS2. Moreover, overexpression of HMGCS1 reversed the inhibitory effect of knockdown of ACSS2 on the PI3K/AKT/mTOR pathway. CONCLUSION: Our study revealed that hypoxia can upregulate the lipid metabolism-related gene ACSS2, which plays a tumorigenic effect by regulating lipid metabolism through activating the PI3K/AKT/mTOR pathway. In addition, HMGCS1 can reverse the oncogenic effects of ACSS2, providing a new option for therapeutic strategy.

FOXA2-initiated transcriptional activation of INHBA induced by methylmalonic acid promotes pancreatic neuroendocrine neoplasm progression.

Pancreatic neuroendocrine neoplasms (PanNENs) are a group of highly heterogeneous neoplasms originating from the endocrine islet cells of the pancreas with characteristic neuroendocrine differentiation, more than 60% of which represent metastases when diagnosis, causing major tumor-related death. Metabolic alterations have been recognized as one of the hallmarks of tumor metastasis, providing attractive therapeutic targets. However, little is known about the molecular mechanism of metabolic changes regulating PanNEN progression. In this study, we first identified methylmalonic acid (MMA) as an oncometabolite for PanNEN progression, based on serum metabolomics of metastatic PanNEN compared with non-metastatic PanNEN patients. One of the key findings was the potentially novel mechanism of epithelial-mesenchymal transition (EMT) triggered by MMA. Inhibin ßA (INHBA) was characterized as a key regulator of MMA-induced PanNEN progression according to transcriptomic analysis, which has been validated in vitro and in vivo. Mechanistically, INHBA was activated by FOXA2, a neuroendocrine (NE) specific transcription factor, which was initiated during MMA-induced progression. In addition, MMA-induced INHBA upregulation activated downstream MITF to regulate EMT-related genes in PanNEN cells. Collectively, these data suggest that activation of INHBA via FOXA2 promotes MITF-mediated EMT during MMA inducing PanNEN progression, which puts forward a novel therapeutic target for PanNENs.

ALKBH5 enhances lipid metabolism reprogramming by increasing stability of FABP5 to promote pancreatic neuroendocrine neoplasms progression in an m6A-IGF2BP2-dependent manner.

The process of post-transcriptional regulation has been recognized to be significantly impacted by the presence of N6-methyladenosine (m6A) modification. As an m6A demethylase, ALKBH5 has been shown to contribute to the progression of different cancers by increasing expression of several oncogenes. Hence, a better understanding of the key targets of ALKBH5 in cancer cells could potentially lead to the development of new therapeutic targets. However, the specific role of ALKBH5 in pancreatic neuroendocrine neoplasms (pNENs) remains largely unknown. Here, we demonstrated that ALKBH5 was up-regulated in pNENs and played a critical role in tumor growth and lipid metabolism. Mechanistically, ALKBH5 over-expression was found to increase the expression of FABP5 in an m6A-IGF2BP2 dependent manner, leading to disorders in lipid metabolism. Additionally, ALKBH5 was found to activate PI3K/Akt/mTOR signaling pathway, resulting in enhanced lipid metabolism and proliferation abilities. In conclusion, our study uncovers the ALKBH5/IGF2BP2/FABP5/mTOR axis as a mechanism for aberrant m6A modification in lipid metabolism and highlights a new molecular basis for the development of therapeutic strategies for pNENs treatment.

Down-regulated FTO and ALKBH5 co-operatively activates FOXO signaling through m6A methylation modification in HK2 mRNA mediated by IGF2BP2 to enhance glycolysis in colorectal cancer.

BACKGROUND: N6-methyladenosine (m6A) modification is the most abundant reversible methylation modification in eukaryotes, and it is reportedly closely associated with a variety of cancers progression, including colorectal cancer (CRC). This study showed that activated lipid metabolism and glycolysis play vital roles in the occurrence and development of CRC. However, only a few studies have reported the biological mechanisms underlying this connection. METHODS: Protein and mRNA levels of FTO and ALKBH5 were measured using western blot and qRT-PCR. The effects of FTO and ALKBH5 on cell proliferation were examined using CCK-8, colony formation, and EdU assays, and the effects on cell migration and invasion were tested using a transwell assay. m6A RNA immunoprecipitation (MeRIP) and RNA-seq was used to explore downstream target gene. RIP was performed to verify the interaction between m6A and HK2. The function of FTO and ALKBH5 in vivo was determined by xenograft in nude mice. RESULTS: In this study, FTO and ALKBH5 were significantly down-regulated in CRC patients and cells both in vivo and in vitro in a high-fat environment. Moreover, FTO and ALKBH5 over-expression hampered cell proliferation both in vitro and in vivo. Conversely, FTO and ALKBH5 knockdown accelerated the malignant biological behaviors of CRC cells. The mechanism of action of FTO and ALKBH5 involves joint regulation of HK2, a key enzyme in glycolysis, which was identified by RNA sequencing and MeRIP-seq. Furthermore, reduced expression of FTO and ALKBH5 jointly activated the FOXO signaling pathway, which led to enhanced proliferation ability in CRC cells. IGF2BP2, as a m6A reader, positively regulated HK2 mRNA in m6A dependent manner. Additionally, down-regulation of FTO/ALKBH5 increased METTL3 and decreased METTL14 levels, further promoting CRC progression. CONCLUSION: In conclusion, our study revealed the FTO-ALKBH5/IGF2BP2/HK2/FOXO1 axis as a mechanism of aberrant m6A modification and glycolysis regulation in CRC.

FAM201A encodes small protein NBASP to inhibit neuroblastoma progression via inactivating MAPK pathway mediated by FABP5.

Increasing evidence indicates that long non-coding RNA (lncRNA) is one of the most important RNA regulators in the pathogenesis of neuroblastoma (NB). Here, we found that FAM201A was low expressed in NB and a variety of gain and loss of function studies elucidated the anti-tumor effects of FAM201A on the regulation of proliferation, migration and invasion of NB cells. Intriguingly, we identified the ability of FAM201A to encode the tumor-suppressing protein, NBASP, which interacted with FABP5 and negatively regulated its expression. In vivo assays also revealed NBASP repressed NB growth via inactivating MAPK pathway mediated by FABP5. In conclusion, our findings demonstrated that NBASP encoded by FAM201A played a tumor-suppressor role in NB carcinogenesis via down-regulating FABP5 to inactivate the MAPK pathway. These results extended our understanding of the relationship of lncRNA-encoded functional peptides and plasticity of tumor progression.

WTAP activates MAPK signaling through m6A methylation in VEGFA mRNA-mediated by YTHDC1 to promote colorectal cancer development.

N6-methyladenosine modification, especially Wilms tumor 1-associated protein (WTAP), is reportedly associated with a variety of cancers, including colorectal cancer (CRC). Angiogenesis also plays an important role in the occurrence and development of CRC. However, only a few studies have reported the biological mechanisms underlying this connection. Therefore, tissue microarray and public database were used to explore WTAP levels in CRC. Then, WTAP was down-regulated and over-expressed, respectively. CCK8, EdU, colony formation, and transwell experiments were performed to study the role of WTAP in CRC. Combined RNA sequencing and m6A RNA immunoprecipitation (MeRIP) sequencing, we found downstream molecules VEGFA. Moreover, a tube formation assay was executed for tumor angiogenesis. Finally, a subcutaneous tumorigenesis assay in nude mice was used to examine the tumor-promoting effect of WTAP in vivo. In the present study, WTAP was significantly upregulated in CRC cells and patients with CRC. Moreover, higher WTAP expression was observed in the TCGA and CPATC databases in CRC tissues. WTAP over-expression exacerbates cell proliferation, migration, invasion, and angiogenesis. Conversely, WTAP knockdown inhibited the malignant biological behavior of CRC cells. Mechanistically, WTAP positively regulated VEGFA, as identified using RNA sequencing and MeRIP sequencing. Moreover, we identified YTHDC1 as a downstream effector of the YTHDC1-VEGFA axis in CRC. Furthermore, increased WTAP expression activated the MAPK signaling pathway, which led to enhanced angiogenesis. In conclusion, our study revealed that the WTAP/YTHDC1/VEGFA axis promotes CRC development, especially angiogenesis, suggesting that it may act as a potential biomarker of CRC.

Methylmalonic acid promotes colorectal cancer progression via activation of Wnt/ß-catenin pathway mediated epithelial-mesenchymal transition.

BACKGROUND: It has been manifested in several studies that age-related metabolic reprogramming is associated with tumor progression, in particular, colorectal cancer (CRC). Here we investigated the role of upregulated metabolites of the aged serum, including methylmalonic acid (MMA), phosphoenolpyruvate (PEP), and quinolinate (QA), in CRC. METHODS: Functional assays including CCK-8, EdU, colony formation and transwell experiments were used to ascertain which upregulated metabolite of elderly serum was related to tumor progression. RNA-seq analysis was conducted to explore the potential mechanisms of MMA-induced CRC progression. Subcutaneous tumorigenesis and metastatic tumor models were constructed to verify the function of MMA in vivo. RESULTS: Among three consistently increased metabolites of the aged sera, MMA was responsible for tumorigenesis and metastasis in CRC, according to functional assays. The promotion of Epithelial-mesenchymal transition (EMT) was observed in CRC cells treated with MMA, on the basis of protein expression of EMT markers. Moreover, combined with transcriptome sequencing, Wnt/ß-catenin signaling pathway was activated in CRC cells treated with MMA, which was verified by western blot and qPCR experiments. Furthermore, animal assays demonstrated the pro-proliferation and promotion of metastasis role of MMA in vivo. CONCLUSION: We have identified that age-dependent upregulation of MMA in serum promoted the progression of CRC via Wnt/ß-catenin signaling pathway mediated EMT. These collective findings provide valuable insights into the vital role of age-related metabolic reprogramming in CRC progression and propose a potential therapeutic target for elderly CRC.

FABP5 suppresses colorectal cancer progression via mTOR-mediated autophagy by decreasing FASN expression.

Lipid metabolism plays an important role in the occurrence and development of cancer, in particular, digestive system tumors such as colon cancer. Here, we investigated the role of the fatty acid-binding protein 5 (FABP5) in colorectal cancer (CRC). We observed marked down-regulation of FABP5 in CRC. Data from functional assays revealed inhibitory effects of FABP5 on cell proliferation, colony formation, migration, invasion as well as tumor growth in vivo. In terms of mechanistic insights, FABP5 interacted with fatty acid synthase (FASN) and activated the ubiquitin proteasome pathway, leading to a decrease in FASN expression and lipid accumulation, moreover, suppressing mTOR signaling and facilitating cell autophagy. Orlistat, a FASN inhibitor, exerted anti-cancer effects both in vivo and in vitro. Furthermore, the upstream RNA demethylase ALKBH5 positively regulated FABP5 expression via an m6A-independent mechanism. Overall, our collective findings offer valuable insights into the critical role of the ALKBH5/FABP5/FASN/mTOR axis in tumor progression and uncover a potential mechanism linking lipid metabolism to development of CRC, providing novel therapeutic targets for future interventions.

Orlistat Induces Ferroptosis in Pancreatic Neuroendocrine Tumors by Inactivating the MAPK Pathway.

Background: Orlistat is an antiobesity drug approved by the US Food and Drug Administration (FDA) with potential antitumor activity against a few malignant tumors, however, whether orlistat affects the progression of pancreatic neuroendocrine tumors (pNETs) remains unknown. Methods: Protein and mRNA levels of FASN were measured using western blotting (WB) and qRT-PCR. The effects of FASN and orlistat on cell proliferation were examined using CCK-8, colony formation, and EdU assays. The effects of FASN and orlistat on cell migration and invasion were tested using a transwell assay. A lipid peroxidation assay was used to explore the effects of orlistat on ferroptosis. The function of orlistat in vivo was determined by xenograft in nude mice. Results: Based on the results of WB and qRT-PCR, FASN was significantly up-regulated in pNET cell lines and public database indicated increased expression of FASN correlated with poor prognosis for patients with pNET. CCK-8, colony formation, and EdU assays showed that knockdown of FASN or treatment with orlistat suppressed the proliferation of pNET cells. The transwell assay indicated that the knockdown of FASN or treatment with orlistat inhibited the migration and invasion of pNET cells. WB and the peroxidation assay showed that orlistat induced ferroptosis in pNET cells. Moreover, orlistat was also found to inhibit the MAPK pathway in pNETs. Furthermore, orlistat showed excellent anti-tumor effects in xenografts in nude mice. Conclusion: Altogether, our study demonstrates that orlistat inhibits the progression of pNETs by inducing ferroptosis mediated by inactivation of the MAPK signaling pathway. Therefore, orlistat is a promising candidate for the treatment of pNETs.

FABP5 regulates lipid metabolism to facilitate pancreatic neuroendocrine neoplasms progression via FASN mediated Wnt/ß-catenin pathway.

Pancreatic neuroendocrine neoplasms (pNENs) are among the most frequently occurring neuroendocrine neoplasms (NENs) and require targeted therapy. High levels of fatty acid binding protein 5 (FABP5) are involved in tumor progression, but its role in pNENs remains unclear. We investigated the mRNA and protein levels of FABP5 in pNEN tissues and cell lines and found them to be upregulated. We evaluated changes in cell proliferation using CCK-8, colony formation, and 5-ethynyl-2'-deoxyuridine assays and examined the effects on cell migration and invasion using transwell assays. We found that knockdown of FABP5 suppressed the proliferation, migration, and invasion of pNEN cell lines, while overexpression of FABP5 had the opposite effect. Co-immunoprecipitation experiments were performed to clarify the interaction between FABP5 and fatty acid synthase (FASN). We further showed that FABP5 regulates the expression of FASN via the ubiquitin proteasome pathway and both proteins facilitate the progression of pNENs. Our study demonstrated that FABP5 acts as an oncogene by promoting lipid droplet deposition and activating the WNT/ß-catenin signaling pathway. Moreover, the carcinogenic effects of FABP5 can be reversed by orlistat, providing a novel therapeutic intervention option.

Novel insights into the interplay between m6A modification and programmed cell death in cancer.

N6-methyladenosine (m6A) methylation, the most prevalent and abundant RNA modification in eukaryotes, has recently become a hot research topic. Several studies have indicated that m6A modification is dysregulated during the progression of multiple diseases, especially in cancer development. Programmed cell death (PCD) is an active and orderly method of cell death in the development of organisms, including apoptosis, autophagy, pyroptosis, ferroptosis, and necroptosis. As the study of PCD has become increasingly profound, accumulating evidence has revealed the mutual regulation of m6A modification and PCD, and their interaction can further influence the sensitivity of cancer treatment. In this review, we summarize the recent advances in m6A modification and PCD in terms of their interplay and potential mechanisms, as well as cancer therapeutic resistance. Our study provides promising insights and future directions for the examination and treatment of cancers.

MYBL2 accelerates epithelial-mesenchymal transition and hepatoblastoma metastasis via the Smad/SNAI1 pathway.

Hepatoblastoma (HB) accounts for the majority of hepatic malignancies in children. Although the prognosis of patients with HB has improved in past decades, metastasis is an indicator of poor overall survival. Herein, we applied single-cell RNA sequencing to explore the transcriptomic profiling of 25,264 metastatic cells isolated from the lungs of two patients with HB. The transcriptomes uncovered the heterogeneity of malignant cells after metastatic lung colonization, and these cells had varied expression signatures associated with the cell cycle, epithelial-mesenchymal plasticity, and hepatic differentiation. Single-cell regulatory network inference and clustering (SCENIC) was utilized to identify the co-expressed transcriptional factors which regulated and represented the different cell states. We further screened the key factor by bioinformatics analysis and found that MYBL2 upregulation was significantly associated with metastasis and poor prognosis. The relationship between ectopic MYBL2 and metastasis was subsequently proved by immunohistochemistry (IHC) of HB tissues, and the functions of MYBL2 in promoting proliferation, migration, and epithelial-to-mesenchymal transition (EMT) were verified by in vitro and in vivo assays. Importantly, the levels of Smad2/3 phosphorylation and SNAI1 expression were increased in MYBL2-transfected cells. Consequently, these results indicated that the MYBL2-controlled Smad/SNAI1 pathway induced EMT and promoted HB tumorigenesis and metastasis.

Downregulation of MEG3 and upregulation of EZH2 cooperatively promote neuroblastoma progression.

Neuroblastoma (NB), an embryonic tumour originating from sympathetic crest cells, is the most common extracranial solid tumour type in children with poor overall prognosis. Accumulating evidence has demonstrated the involvement of long non-coding RNA (lncRNA) in numerous biological processes and their associations with embryonic development and multiple diseases. Ectopic lncRNA expression is linked to malignant tumours. Previous studies by our team indicate that MEG3 attenuates NB autophagy through inhibition of FOXO1 and epithelial-mesenchymal transition via the mTOR pathway in vitro. Moreover, MEG3 and EZH2 negatively regulate each other. In present study, we first collected 60 NB tissues and 20 adjacent tissues for Quantitative real-time polymerase chain reaction (Q-PCR) experiments and performed clinical correlation analysis of the results. At the same time, nude mice were used for subcutaneous tumour formation to detect the effect of MEG3 in vivo. Two NB cell lines, SK-N-AS and SK-N-BE(2)C, were overexpressed MEG3 and rescued with EZH2 and then were subjected to proliferation, migration, invasion, apoptosis and autophagy experiments. RNA-binding protein immunoprecipitation (RIP) and Co-Immunoprecipitation (Co-IP) experiments were performed to explore the molecular mechanism of MEG3 and EZH2 interaction. Q-PCR revealed that MEG3 expression was negatively correlated with INSS stage and risk grade of NB. Moreover, MEG3 overexpression was associated with inhibition of NB growth in vivo. MEG3 exerted an anti-cancer effect via stimulatory effects on EZH2 ubiquitination leading to its degradation. Conversely, EZH2 interacted with DNMT1 and HDAC1 to induce silencing of MEG3. The EZH2 inhibitor, DZNep, and HDAC inhibitor, SAHA, displayed synergistic activity against NB. Combined treatment with DZNep and SAHA inhibited proliferation, migration and invasion of NB through suppression of the PI3K/AKT/mTOR/FOXO1 pathway. In conclusion, downregulation of MEG3 and upregulation of EZH2 forms a feedback loop that concertedly promotes the development of NB. Combined blockage of EZH2 and HDAC1 with the appropriate inhibitors may therefore present an effective treatment strategy for NB cases with low MEG3 and high EZH2 expression.

m6A Modification: A Double-Edged Sword in Tumor Development.

Modification of m6A, as the most abundant mRNA modification, plays diverse roles in various biological processes in eukaryotes. Emerging evidence has revealed that m6A modification is closely associated with the activation and inhibition of tumor pathways, and it is significantly linked to the prognosis of cancer patients. Aberrant reduction or elevated expression of m6A regulators and of m6A itself have been identified in numerous tumors. In this review, we give a description of the dynamic properties of m6A modification regulators, such as methyltransferases, demethylases, and m6A binding proteins, and indicate the value of the balance between these proteins in regulating the expression of diverse genes and the underlying effects on cancer development. Furthermore, we summarize the "dual-edged weapon" role of RNA methylation in tumor progression and discuss that RNA methylation can not only result in tumorigenesis but also lead to suppression of tumor formation. In addition, we summarize the latest research progress on small-molecule targeting of m6A regulators to inhibit or activate m6A. These studies indicate that restoring the balance of m6A modification via targeting specific imbalanced regulators may be a novel anti-cancer strategy.

SP1-Mediated Upregulation of Long Noncoding RNA ZFAS1 Involved in Non-syndromic Cleft Lip and Palate via Inactivating WNT/ß-Catenin Signaling Pathway.

Non-syndromic cleft lip and palate (NSCLP) is one of the most common congenital malformations with multifactorial etiology. Although long non-coding RNAs (lncRNAs) have been implicated in the development of lip and palate, their roles in NSCLP are not fully elucidated. This study aimed to investigate how dysregulated lncRNAs contribute to NSCLP. Using lncRNA sequencing, bioinformatics analysis, and clinical tissue sample detection, we identified that lncRNA ZFAS1 was significantly upregulated in NSCLP. The upregulation of ZFAS1 mediated by SP1 transcription factor (SP1) inhibited expression levels of Wnt family member 4 (WNT4) through the binding with CCCTC-binding factor (CTCF), subsequently inactivating the WNT/ß-catenin signaling pathway, which has been reported to play a significant role on the development of lip and palate. Moreover, in vitro, the overexpression of ZFAS1 inhibited cell proliferation and migration in human oral keratinocytes and human umbilical cord mesenchymal stem cells (HUC-MSCs) and also repressed chondrogenic differentiation of HUC-MSCs. In vivo, ZFAS1 suppressed cell proliferation and numbers of chondrocyte in the zebrafish ethmoid plate. In summary, these results indicated that ZFAS1 may be involved in NSCLP by affecting cell proliferation, migration, and chondrogenic differentiation through inactivating the WNT/ß-catenin signaling pathway.

[Corrigendum] Linc01105 acts as an oncogene in the development of neuroblastoma.

Subsequently to the publication of the above article, the authors have found that Fig. 4A on p. 1532 contained some errors. Owing to mistakes made during the preparation and revision of the manuscript, the invasion assay data images selected to show both the 'Control' and 'shRNA2' groups of the invasion and migration experiments were derived from the same original sources. A corrected version of the Fig. 4, showing the correct data for the invasion and migration assay experiments with the Control and shRNA2 groups, is shown below. These inadvertent errors did not affect the conclusions reported in this paper, and all the authors agree with this Corrigendum. The authors thank the editor of Oncology Reports for presenting them with the opportunity to publish this Corrigendum, and apologize to the editor and to the readership of the journal for any inconvenience caused. [the original article was published in Oncology Reports 42: 1527-1538, 2019; DOI: 10.3892/or.2019.7257].

USP7 promotes hepatoblastoma progression through activation of PI3K/AKT signaling pathway.

BACKGROUND: Hepatoblastoma (HB) is an embryonic solid tumor and the most common primary malignant liver tumor in children. HB usually occurs in infants and children. Although treatment diversity is increasing, some patients still have very poor prognosis. Many studies have investigated USP7 inhibitors for tumors. Using database information, we found that USP7 is highly expressed in HB. METHODS: Lentivirus-mediated USP7 knockdown and overexpression was performed in HB cell lines HepG2 and Huh6. CCK8 and transwell assays were used to determine cell viability and metastasis. Flow cytometry was used to study cell cycle and apoptosis. Levels of proteins were detected using western blots. RESULTS: Downregulation of USP7 resulted in significant decrease in cell proliferation, clonal formation, and cell migration and invasion. With overexpression of USP7, cellular malignant behavior increased. Cell cycle assays showed that USP7 knockdown inhibited G1 to S phase transition in the cell cycle. Upregulation of USP7 promoted the transition. Animal experiments showed USP7 facilitated tumor growth in vivo. Western blots indicated that USP7 may affect HB tumorigenesis through the PI3K/AKT signaling pathway. Furthermore, USP7 inhibitor P5091 inhibited HB development and PI3K/AKT pathway. CONCLUSION: USP7 upregulation contributed to HB genesis and development through the PI3K/AKT signaling pathway. USP7 could be a potential target for future HB treatment.