Search

Cumulative studies have established the significance of transfer RNA-derived small RNA (tsRNA) in tumorigenesis and progression. Nevertheless, its function and mechanism in pancreatic cancer metastasis remain largely unclear. Here, we screened and identified tiRNA-Val-CAC-2 as highly expressed in pancreatic cancer metastasis samples by tsRNA sequencing. We also observed elevated levels of tiRNA-Val-CAC-2 in the serum of pancreatic cancer patients who developed metastasis, and patients with high levels of tiRNA-Val-CAC-2 exhibited a worse prognosis. Additionally, knockdown of tiRNA-Val-CAC-2 inhibited the metastasis of pancreatic cancer in vivo and in vitro, while overexpression of tiRNA-Val-CAC-2 promoted the metastasis of pancreatic cancer. Mechanically, we discovered that tiRNA-Val-CAC-2 interacts with FUBP1, leading to enhanced stability of FUBP1 protein and increased FUBP1 enrichment in the c-MYC promoter region, thereby boosting the transcription of c-MYC. Of note, rescue experiments confirmed that tiRNA-Val-CAC-2 could influence pancreatic cancer metastasis via FUBP1-mediated c-MYC transcription. These findings highlight a potential novel mechanism underlying pancreatic cancer metastasis, and suggest that both tiRNA-Val-CAC-2 and FUBP1 could serve as promising prognostic biomarkers and potential therapeutic targets for pancreatic cancer., (© 2024. The Author(s).)

The molecular mechanism of glioblastoma (GBM) radiation resistance remains poorly understood. The aim of this study was to elucidate the potential role of Melanophilin (MLPH) O-GlcNAcylation and the specific mechanism through which it regulates GBM radiotherapy resistance. We found that MLPH was significantly upregulated in recurrent GBM tumor tissues after ionizing radiation (IR). MLPH induced radiotherapy resistance in GBM cells and xenotransplanted human tumors through regulating the NF-κB pathway. MLPH was O-GlcNAcylated at the conserved serine 510, and radiation-resistant GBM cells showed higher levels of O-GlcNAcylation of MLPH. O-GlcNAcylation of MLPH protected its protein stability and tripartite motif containing 21(TRIM21) was identified as an E3 ubiquitin ligase promoting MLPH degradation whose interaction with MLPH was affected by O-GlcNAcylation. Our data demonstrate that MLPH exerts regulatory functions in GBM radiation resistance by promoting the NF-κB signaling pathway and that O-GlcNAcylation of MLPH both stabilizes and protects it from TRIM21-mediated ubiquitination. These results identify a potential mechanism of GBM radiation resistance and suggest a potential therapeutic strategy for GBM treatment., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

Aberrant hyperactivation of the Hippo pathway effector YAP/TEAD complex causes tissue overgrowth and tumorigenesis in various cancers, including endometrial cancer (EC). The transcription factor SOX17 (SRY [sex-determining region Y]-box 17) is frequently mutated in EC; however, SOX17 mutations are rare in other cancer types. The molecular mechanisms underlying SOX17 mutation-induced EC tumorigenesis remain poorly understood. Here, we demonstrate that SOX17 serves as a tumor suppressor to restrict the proliferation, migration, invasion, and anchorage-independent growth of EC cells, partly by suppressing the transcriptional outputs of the Hippo-YAP/TEAD pathway. SOX17 binds to TEAD transcription factors through its HMG domain and attenuates the DNA-binding ability of TEAD. SOX17 loss by inactivating mutations leads to the malignant transformation of EC cells, which can be reversed by small-molecule inhibitors of YAP/TEAD or cabozantinib, an FDA-approved drug targeting the YAP/TEAD transcriptional target AXL. Our findings reveal novel molecular mechanisms underlying Hippo-YAP/TEAD pathway-driven EC tumorigenesis, and suggest potential therapeutic strategies targeting the Hippo-YAP/TEAD pathway in SOX17-mutated EC., (© 2022. The Author(s), under exclusive licence to Springer Nature Limited.)

Activating RAS mutations are found in a subset of fusion-negative rhabdomyosarcoma (RMS), and therapeutic strategies to directly target RAS in these tumors have been investigated, without clinical success to date. A potential strategy to inhibit oncogenic RAS activity is the disruption of RAS prenylation, an obligate step for RAS membrane localization and effector pathway signaling, through inhibition of farnesyltransferase (FTase). Of the major RAS family members, HRAS is uniquely dependent on FTase for prenylation, whereas NRAS and KRAS can utilize geranylgeranyl transferase as a bypass prenylation mechanism. Tumors driven by oncogenic HRAS may therefore be uniquely sensitive to FTase inhibition. To investigate the mutation-specific effects of FTase inhibition in RMS we utilized tipifarnib, a potent and selective FTase inhibitor, in in vitro and in vivo models of RMS genomically characterized for RAS mutation status. Tipifarnib reduced HRAS processing, and plasma membrane localization leading to decreased GTP-bound HRAS and decreased signaling through RAS effector pathways. In HRAS-mutant cell lines, tipifarnib reduced two-dimensional and three-dimensional cell growth, and in vivo treatment with tipifarnib resulted in tumor growth inhibition exclusively in HRAS-mutant RMS xenografts. Our data suggest that small molecule inhibition of FTase is active in HRAS-driven RMS and may represent an effective therapeutic strategy for a genomically-defined subset of patients with RMS., (© 2022. The Author(s).)

Despite advances in clinical diagnosis and treatment, the prognosis of patients with osteosarcoma (OS) remains poor, and the treatment efficacy has plateaued. Therefore, it is important to identify new therapeutic targets for OS. N 6 -methyladenosine (m 6 A) modification has been reported to participate in tumor malignancy. In this study, functional screening showed that the m 6 A demethylase FTO could be a candidate therapeutic target for OS. Upregulated FTO in OS could predict a poorer prognosis. FTO promoted the growth and metastasis of OS in vitro and in vivo. Methylated RNA immunoprecipitation sequencing (MeRIP-seq) and RNA sequencing (RNA-seq) were performed to identify DACT1 as a potential target of FTO. In vitro assays demonstrated that FTO could reduce the mRNA stability of DACT1 via m 6 A demethylation, which decreased DACT1 expression and further activated the Wnt signaling pathway. The oncogenic effect of FTO on OS was dependent on DACT1. In addition, the m 6 A reader IGF2BP1 was validated to participate in the regulation of DACT1. Entacapone, a conventional drug for Parkinson's disease, was confirmed to suppress OS via m 6 A-mediated regulation through the FTO/DACT1 axis. Our findings demonstrate that FTO may be a novel therapeutic target and that entacapone has preclinical value to be repurposed for OS., (© 2022. The Author(s), under exclusive licence to Springer Nature Limited.)

We recently reported that genetic or pharmacological inhibition of insulin-like growth factor receptor (IGF-1R) slows DNA replication and induces replication stress by downregulating the regulatory subunit RRM2 of ribonucleotide reductase, perturbing deoxynucleotide triphosphate (dNTP) supply. Aiming to exploit this effect in therapy we performed a compound screen in five breast cancer cell lines with IGF neutralising antibody xentuzumab. Inhibitor of checkpoint kinase CHK1 was identified as a top screen hit. Co-inhibition of IGF and CHK1 caused synergistic suppression of cell viability, cell survival and tumour growth in 2D cell culture, 3D spheroid cultures and in vivo. Investigating the mechanism of synthetic lethality, we reveal that CHK1 inhibition in IGF-1R depleted or inhibited cells further downregulated RRM2, reduced dNTP supply and profoundly delayed replication fork progression. These effects resulted in significant accumulation of unreplicated single-stranded DNA and increased cell death, indicative of replication catastrophe. Similar phenotypes were induced by IGF:WEE1 co-inhibition, also via exacerbation of RRM2 downregulation. Exogenous RRM2 expression rescued hallmarks of replication stress induced by co-inhibiting IGF with CHK1 or WEE1, identifying RRM2 as a critical target of the functional IGF:CHK1 and IGF:WEE1 interactions. These data identify novel therapeutic vulnerabilities and may inform future trials of IGF inhibitory drugs., (© 2021. The Author(s).)

Invasion and metastasis are the leading causes of death in patients with breast cancer (BC), and epithelial-mesenchymal transformation (EMT) plays an essential role in this process. Here, we found that Lnc-408, a novel long noncoding RNA (lncRNA), is significantly upregulated in BC cells undergoing EMT and in BC tumor with lymphatic metastases compared with those without lymphatic metastases. Lnc-408 can enhance BC invasion and metastasis by regulating the expression of LIMK1. Mechanistically, Lnc-408 serves as a sponge for miR-654-5p to relieve the suppression of miR-654-5p on its target LIMK1. Knockdown or knockout of Lnc-408 in invasive BC cells clearly decreased LIMK1 levels, and ectopic Lnc-408 in MCF-7 cells increased LIMK1 expression to promote cell invasion. Lnc-408-mediated enhancement of LIMK1 plays a key role in cytoskeletal stability and promotes invadopodium formation in BC cells via p-cofilin/F-actin. In addition, the increased LIMK1 also facilitates the expression of MMP2, ITGB1, and COL1A1 by phosphorylating CREB. In conclusion, our findings reveal that Lnc-408 promotes BC invasion and metastasis via the Lnc-408/miR-654-5p/LIMK1 axis, highlighting a novel promising target for the diagnosis and treatment of BC.

The hostile hypoxic microenvironment takes primary responsibility for the rapid expansion of breast cancer tumors. However, the underlying mechanism is not fully understood. Here, using RNA sequencing (RNA-seq) analysis, we identified a hypoxia-induced long noncoding RNA (lncRNA) KB-1980E6.3, which is aberrantly upregulated in clinical breast cancer tissues and closely correlated with poor prognosis of breast cancer patients. The enhanced lncRNA KB-1980E6.3 facilitates breast cancer stem cells (BCSCs) self-renewal and tumorigenesis under hypoxic microenvironment both in vitro and in vivo. Mechanistically, lncRNA KB-1980E6.3 recruited insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1) to form a lncRNA KB-1980E6.3/IGF2BP1/c-Myc signaling axis that retained the stability of c-Myc mRNA through increasing binding of IGF2BP1 with m6A-modified c-Myc coding region instability determinant (CRD) mRNA. In conclusion, we confirm that lncRNA KB-1980E6.3 maintains the stemness of BCSCs through lncRNA KB-1980E6.3/IGF2BP1/c-Myc axis and suggest that disrupting this axis might provide a new therapeutic target for refractory hypoxic tumors.

Endometrial cancer (EC) is a common gynaecological cancer worldwide. Exosomes, secreted by living cells and detected in various body fluids, can exchange information between organs and compartments to affect cellular functions, such as proliferation, apoptosis, migration and angiogenesis. We hypothesise that plasma exosomal contents are altered during cancer progression and promote cancer growth and angiogenesis by delivering biomolecules to cancer and vascular endothelial cells. In this study, circulating exosomes derived from EC patients and age-matched healthy people were acquired by commercial kits. Cell counting kit-8, Transwell and Matrigel tube formation assays showed that circulating exosomes from EC patients promote EC cell growth and human umbilical vein endothelial cell (HUVEC) angiogenesis. Next, proteomic analysis and ELISA revealed that plasma exosomal lectin galactoside-binding soluble 3 binding protein (LGALS3BP) increased during EC progression. Moreover, to explore the function of exosomal LGALS3BP, we acquired exosomes containing high levels of LGALS3BP by overexpressing LGALS3BP in human embryonic kidney 293 cells, and we demonstrated that highly contained exosomal LGALS3BP contributed to EC cell proliferation and migration and HUVEC functions via the activation of the PI3K/AKT/VEGFA signalling pathway both in vitro and in vivo. Finally, high LGALS3BP expression was observed in human EC tissue, which indicated a poor prognosis. In addition, immunohistochemical analysis of human EC tissues revealed that LGALS3BP expression was correlated with VEGFA expression and blood vessel density. Hence, we proposed that plasma exosomes containing LGALS3BP contributed to EC growth and angiogenesis during EC progression, which also provided a novel perspective on EC diagnosis and prognosis.

Epigenetic changes that cause dysregulated gene expression during progression of androgen-independent prostate cancer (PCa) and metastatic skeletal lesions remain elusive. Here, we explored the role of histone demethylase NO66 in the pathogenesis of PCa and bone metastasis-related skeletal lesions. Tissue and cDNA microarrays of PCa were analyzed for NO66 mRNA and protein levels. We examined the effects of gain and loss of NO66 function on cell viability, colony formation, migration, invasion, and tumor-induced skeletal lesions in femoral bone. RNAseq and ChIPseq were performed to elucidate NO66-target genes in PCa. We report that NO66 levels were upregulated in advanced primary prostate tumors compared to normal tissue or tumors with low Gleason scores. Forced expression of NO66 promoted cell survival and invasion of PCa cells; whereas, knockdown of NO66 resulted in decreased cell survival and increased sensitivity to docetaxel. NO66-overexpressing PC3 cells implanted into the femoral bone of male SCID mice caused massive bone loss and stimulation of mouse osteoclast-promoting genes, including Dickkopf1, Cathepsin K, Nf-kβ,; and Calcr, suggesting a role for NO66 in tumor growth in bone and osteoclast activity. Combined RNAseq and ChIP-seq revealed that NO66 activates the survival gene MCL1, the invasion-associated genes IGFBP5 and MMP3, the pro-oncogenic genes CTNNB1 and CCND1, and the epigenetic modifier gene KMT2A in androgen-independent PCa. Our findings uncover the role of NO66 as a key oncogenic driver in PCa, causing osteolytic lesions through upstream epigenetic regulation of key genes for survival, invasion and metastasis, and pro-osteoclastic factors.

Constitutive activation of Akt has been found in many types of human cancer, and is believed to promote proliferation and increased cell survival thereby contributing to cancer progression. In this study, we examined Akt phosphorylation on Ser473 and Thr308 in seven IGF-II-overexpressing rhabdomyosarcomas (RMS) cells. All the RMS cell lines tested had high levels of Akt phosphorylation on Thr308, whereas three cell lines (Rh5, Rh18, and CTR) had a much lower level of Akt phosphorylation on Ser473. To determine whether the difference in Akt phosphorylation on Ser473, but not on Thr308, observed among cell lines is a cell-specific phenomenon or due to other factors, which possibly downregulate Akt phosphorylation, we examined expression of PTEN protein, which acts as a negative regulator of the PI3K/Akt signaling pathway through its ability to dephosphorylate phosphatidylinositol 3,4,5-triphosphate (PIP3). The levels of PTEN expression inversely correlate with Akt phosphorylation on Ser473, but not on Thr308. Consistent with this finding, transfection of wild-type PTEN into RMS and mouse myoblast C2C12 cells resulted in reduced Akt phosphorylation on Ser473, but not on Thr308. Our data suggest that Ser473 may be a key target residue for PTEN to modulate the effects of IGF-II on activating the PI3K/Akt pathway in RMS cells. A better understanding of the pathway in RMS will likely contribute to insights into the biology of the RMS tumorigenesis and hopefully lead to novel therapeutic options.