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The major function of Insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2) is to regulate cell metabolism. However, emerging evidence indicates that IGF2BP2 plays a role in cancer, but the underlying mechanism is largely unknown. Here we showed that upregulation of IGF2BP2 is associated with poor outcomes of pancreatic cancer patients and suppression of IGF2BP2 inhibits cell proliferation. We further showed that IGF2BP2 regulates lncRNA DANCR. Ectopic expression IGF2BP2 enhances, whereas knockdown (KD) or knockout (KO) of IGF2BP2 suppresses DANCR expression. Moreover, in vivo RNA precipitation and reciprocal RNA immunoprecipitation revealed that IGF2BP2 interacts with DANCR. DANCR promotes cell proliferation and stemness-like properties. Experiments with xenograft models revealed that while ectopic expression of DANCR promotes, DANCR KO suppresses tumor growth. Mechanistically, DANCR is modified at N6-methyladenosine (m6A) and mutagenesis assay identified that adenosine at 664 of DANCR is critical to the interaction between IGF2BP2 and DANCR where IGF2BP2 serves a reader for m6A modified DANCR and stabilizes DANCR RNA. Together, these results suggest that DANCR is a novel target for IGF2BP2 through m6A modification, and IGF2BP2 and DANCR work together to promote cancer stemness-like properties and pancreatic cancer pathogenesis.

Background The conversion from estrogen-dependent to estrogen-independent state of ER+ breast cancer cells is the key step to promote resistance to endocrine therapies. Although the crucial role of MAPK/ERK signaling pathway in estrogen-independent breast cancer cell growth is well established, the underlying mechanism is not fully understood. Methods In this study, we profiled lncRNA expression against a focused group of lncRNAs selected from lncRNA database. CRISPR/Cas9 was employed to knockout (KO) linc-RoR in MCF-7 cells, while rescue experiments were carried out to re-express linc-RoR in KO cells. Colony formation and MTT assays were used to examine the role of linc-RoR in estrogen-independent growth and tamoxifen resistance. Western blot and qRT-PCR were used to determine the change of protein and lncRNA levels, respectively. The expression of DUSP7 in clinical specimens was downloaded from Oncomine ( www.oncomine.org ) and the dataset from Kaplan-Meier Plotter ( http://kmplot.com ) was used to analyze the clinical outcomes in relation to DUSP7. Results We identified that linc-RoR functions as an onco-lncRNA to promote estrogen-independent growth of ER+ breast cancer. Under estrogen deprivation, linc-RoR causes the upregulation of phosphorylated MAPK/ERK pathway which in turn activates ER signaling. Knockout of linc-RoR abrogates estrogen deprivation-induced ERK activation as well as ER phosphorylation, whereas re-expression of linc-RoR restores all above phenotypes. Moreover, we show that the ERK-specific phosphatase Dual Specificity Phosphatase 7 (DUSP7), also known as MKP-X, is involved in linc-RoR KO-induced repression of MAPK/ERK signaling. Interestingly, linc-RoR KO increases the protein stability of DUSP7, resulting in repression of ERK phosphorylation. Clinical data analysis reveal that DUSP7 expression is lower in ER+ breast cancer samples than that in ER- breast cancer. Moreover, downregulation of DUSP7 expression is associated with poor patient survival. Conclusion Taken together, these results suggest that linc-RoR promotes estrogen-independent growth and activation of MAPK/ERK pathway of breast cancer cells by regulating the ERK-specific phosphatase DUSP7. Thus, this study might help not only in establishing a role for linc-RoR in estrogen-independent and tamoxifen resistance of ER+ breast cancer, but also suggesting a link between linc-RoR and MAPK/ERK pathway.

Although multiple factors are known to contribute to pancreatic ductal adenocarcinoma (PDAC) progression, the role of long non-coding RNAs (lncRNAs) in PDAC remains largely unknown. In this study, we present data that long intergenic non-coding RNA 346 (LINC00346) functions as a promoting factor for PDAC development. We first show that LINC00346 is highly expressed in pancreatic tumor specimens as compared to normal pancreatic tissue based on interrogation of The Cancer Genome Atlas (TCGA) pancreatic adenocarcinoma dataset. Of significance, this upregulation of LINC00346 is associated with overall survival (OS) and disease-free survival (DFS), respectively. We further show that knockout (KO) of LINC00346 impairs pancreatic cancer cell proliferation, tumorigenesis, migration, and invasion ability. Importantly, these phenotypes can be restored by LINC00346 re-expression in KO cells (i.e., rescue experiment). RNA precipitation assays combined with mass spectrometry analysis indicate that LINC00346 interacts with CCCTC-binding factor (CTCF), a known transcriptional repressor of c-Myc. This interaction between LINC00346 and CTCF prevents the binding of CTCF to c-Myc promoter, relieving the CTCF-mediated repression of c-Myc. Thus, LINC00346 functions as a positive transcriptional regulator of c-Myc. Together, these results suggest that LINC00346 contributes to PDAC pathogenesis by activating c-Myc, and as such, LINC00346 may serve as a potential biomarker and therapeutic target for PDAC.

Selective estrogen receptor modulators (SERMs) such as tamoxifen have proven to be effective in the treatment of estrogen receptor (ER) positive breast cancer. However, a major obstacle for such endocrine therapy is estrogen independent growth, leading to resistance, and the underlying mechanism is not fully understood. The purpose of this study was to determine whether long non-coding RNAs (lncRNAs) are involved in regulation of estrogen independent growth and tamoxifen resistance in ER positive breast cancer. Using a CRISPR/Cas9-based SAM (synergistic activation mediator) library against a focus group of lncRNAs, we identify Lnc-DC as a candidate lncRNA. Further analysis suggests that Lnc-DC is able to reduce tamoxifen-induced apoptosis by upregulation of anti-apoptotic genes such as Bcl2 and Bcl-xL. Furthermore, Lnc-DC activates STAT3 by phosphorylation (pSTAT3 Y705 ), and the activated STAT3 subsequently induces expression of cytokines which in turn activate STAT3, forming an autocrine loop. Clinically, upregulation of Lnc-DC is associated with poor prognosis. In particular, analysis of a tamoxifen-treated patient cohort indicates that Lnc-DC expression can predict the response to tamoxifen. Together, this study demonstrates a previously uncharacterized function of Lnc-DC/STAT3/cytokine axis in estrogen independent growth and tamoxifen resistance, and Lnc-DC may serve as a potential predictor for tamoxifen response.

Background UCA1 is frequently upregulated in a variety of cancers, including CRC, and it can play an oncogenic role by various mechanisms. However, how UCA1 is regulated in cancer is largely unknown. In this study, we aimed to determine whether RNA methylation at N6-methyladenosine (m6A) can impact UCA1 expression in colorectal cancer (CRC). Methods qRT-PCR was performed to detect the level of UCA1 and IGF2BP2 in CRC samples. CRISPR/Cas9 was employed to knockout (KO) UCA1, METTL3 and WTAP in DLD-1 and HCT-116 cells, while rescue experiments were carried out to re-express METTL3 and WTAP in KO cells. Immunoprecipitation using m6A antibody was performed to determine the m6A modification of UCA1. In vivo pulldown assays using S1m tagging combined with site-direct mutagenesis was carried out to confirm the recognition of m6A-modified UCA1 by IGF2BP2. Cell viability was measured by MTT and colony formation assays. The expression of UCA1 and IGF2BP2 in TCGA CRC database was obtained from GEPIA ( http://gepia.cancer-pku.cn ). Results Our results revealed that IGF2BP2 serves as a reader for m6A modified UCA1 and that adenosine at 1038 of UCA1 is critical to the recognition by IGF2BP2. Importantly, we showed that m6A writers, METTL3 and WTAP positively regulate UCA1 expression. Mechanically, IGF2BP2 increases the stability of m6A-modified UCA1. Clinically, IGF2BP2 is upregulated in CRC tissues compared with normal tissues. Conclusion These results suggest that m6A modification is an important factor contributing to upregulation of UCA1 in CRC tissues.

Background Surgery plays an important role in the treatment of neuroblastoma. Perioperative complications may impact the course of neuroblastoma treatment. To date, comprehensive analyses of complications and risk factors have been lacking. Methods Patients with retroperitoneal neuroblastoma undergoing tumor resection were retrospectively analyzed between 2014 and 2021. The data collected included clinical characteristics, operative details, operative complications and postoperative outcomes. Risk factors for perioperative complications of retroperitoneal neuroblastoma were analyzed. Results A total of 571 patients were enrolled in this study. Perioperative complications were observed in 255 (44.7%) patients. Lymphatic leakage (28.4%), diarrhea (13.5%), and injury (vascular, nerve and organ; 7.5%) were the most frequent complications. There were three operation-related deaths (0.53%): massive hemorrhage ( n  = 1), biliary tract perforation ( n  = 1) and intestinal necrosis ( n  = 1). The presence of image-defined risk factors (IDRFs) [odds ratio (OR) = 2.09, P  < 0.01], high stage of the International Neuroblastoma Risk Group staging system (INRGSS) (OR = 0.454, P  = 0.04), retroperitoneal lymph node metastasis (OR = 2.433, P  = 0.026), superior mesenteric artery encasement (OR = 3.346, P  = 0.003), and inferior mesenteric artery encasement (OR = 2.218, P  = 0.019) were identified as independent risk factors for perioperative complications. Conclusions Despite the high incidence of perioperative complications, the associated mortality rate was quite low. Perioperative complications of retroperitoneal neuroblastoma were associated with IDRFs, INRGSS, retroperitoneal lymph node metastasis and vascular encasement. Patients with high-risk factors should receive more serious attention during surgery but should not discourage the determination to pursue total resection of neuroblastoma. 8e95DYrdivwNpNwDkEtfUx Video Abstract (MP4 94289 KB)

Background Malignant rhabdoid tumor of the kidney (MRTK) is a rare renal tumor with poor prognosis. While germline mutations of SMARCB1 are considered to be the primary cause of MRTK, emerging evidence suggests that somatic epigenetic changes also play a vital role in the development and progression of MRTK. YTHDF1, an m6A reader protein, has been implicated in regulation of tumorigenesis by influencing RNA translation and stability in several adult cancers. However, the exploration of the role of YTHDF1 in pediatric cancer, especially MRTK, remains limited. Methods In this study, CRISPR/Cas9 was employed to knockout (KO) YTHDF1 in G401 cells. The impact of YTHDF1 on the cell growth and chemoresistance were assessed using CCK-8 assays. Western blot and qRT-PCR were used to determine the changes in ferroptosis marker gene expression. Additionally, 4D-label free quantitative proteomics was conducted to uncover alterations by YTHDF1 deletion. Results We observed that the deletion of YTHDF1 in the MRTK cell line led to a significant reduction in malignancy-associated characteristics, including decreased cell motility, invasive growth, and chemoresistance. Quantitative proteomic analysis revealed that the glutathione-related signaling pathway was notably affected by YTHDF1 KO. Specifically, YTHDF1 KO resulted in a reduction of both mRNA and protein levels of Glutathione S-Transferase Mu 2 (GSTM2), a phase II metabolizing enzyme responsible for conjugating glutathione to electrophilic compounds. The decrease in GSTM2 levels following YTHDF1 KO increased the susceptibility of MRTK cells to ferroptosis. Notably, overexpression of GSTM2 in YTHDF1 KO cells partially restored the oncogenic phenotype of MRTK cells, underscoring its role in MRTK progression. Conclusions In summary, our findings provide new insights into the molecular mechanisms driving MRTK progression, highlighting YTHDF1 and GSTM2 as potential therapeutic targets for this aggressive pediatric renal tumor. Graphical Abstract YTHDF1 is highly expressed in MRTK cells. YTHDF1 recognizes the m6A modification on GSTM2 mRNA, enhancing its stability. GSTM2 protects MRTK cells against ferroptosis independent of GPX4.

To date, a large number of long non-coding RNAs (lncRNAs) have been recently discovered through functional genomics studies. Importantly, lncRNAs have been shown, in many cases, to function as master regulators for gene expression and thus, they can play a critical role in various biological functions and disease processes including cancer. Although the lncRNA-mediated gene expression involves various mechanisms, such as regulation of transcription, translation, protein modification, and the formation of RNA–protein or protein–protein complexes, in this review, we discuss the latest developments primarily in important cell signaling pathways regulated by lncRNAs in cancer.