FOXF2 Regulates PRUNE2 Transcription in the Pathogenesis of Colorectal Cancer.

Background: Forkhead box F2, a member of the Forkhead box transcription factor superfamily, plays an important role in several types of cancer. However, the mechanisms of Forkhead box F2 in the progression of colorectal cancer remain unclear. PRUNE2 is closely associated with prostate cancer, neuroblastoma, glioblastoma, and melanoma. The relationship between Forkhead box F2 and PRUNE2 in colorectal cancer remains unknown. Method: We investigated the effects of Forkhead box F2 upregulation on colorectal cancer cell behavior in vitro using Cell Counting Kit-8, colony formation, flow cytometry, Transwell, reverse transcription quantitative polymerase chain reaction and Western blot analyses. Nude mouse xenografts were established to investigate the effect of Forkhead box F2 upregulation on the growth of colorectal cancer cells. Dual-luciferase reporter assays were performed to confirm the Forkhead box F2 regulation of PRUNE2 transcription. A series of in vitro assays was performed in cells with Forkhead box F2 upregulation and PRUNE2 knockdown to elucidate the function and regulatory effects of Forkhead box F2 on PRUNE2 transcription in colorectal cancer. Results: Forkhead box F2 was downregulated in colorectal cancer tissues compared with adjacent tissues. Forkhead box F2 overexpression significantly suppressed the proliferation and invasion of colorectal cancer cells in vitro and in vivo. Moreover, Forkhead box F2 directly targeted PRUNE2 to promote its transcription in colorectal cancer cells. Furthermore, PRUNE2 mediated the Forkhead box F2-regulated proliferation and invasion of colorectal cancer cells. Additionally, we demonstrated a significant positive correlation between Forkhead box F2 and PRUNE2 mRNA levels in colorectal cancer tissues. Conclusion: These results indicated that Forkhead box F2 and PRUNE2 in combination may serve as a prognostic biomarker for colorectal cancer and that Forkhead box F2 upregulation inhibits the proliferation and invasion of colorectal cancer cells by upregulating PRUNE2.

Histone chaperone FACT complex coordinates with HIF to mediate an expeditious transcription program to adapt to poorly oxygenated cancers.

Cancer cells adapt to hypoxia through HIFs (hypoxia-inducible factors), which initiate the transcription of numerous genes for cancer cell survival in the hypoxia microenvironment. In this study, we find that the FACT (facilitates chromatin transcription) complex works cooperatively with HIFs to facilitate the expeditious expression of HIF targets for hypoxia adaptation. Knockout (KO) of the FACT complex abolishes HIF-mediated transcription by impeding transcription elongation in hypoxic cancer cells. Interestingly, the FACT complex is post-translationally regulated by PHD/VHL-mediated hydroxylation and proteasomal degradation, in similar fashion to HIF-1/2α. Metabolic tracing confirms that FACT KO suppresses glycolytic flux and impairs lactate extrusion, leading to intracellular acidification and apoptosis in cancer cells. Therapeutically, hepatic artery ligation and anti-angiogenic inhibitors adversely induce intratumoral hypoxia, while co-treatment with FACT inhibitor curaxin remarkably hinders the growth of hypoxic tumors. In summary, our findings suggest that the FACT complex is a critical component of hypoxia adaptation and a therapeutic target for hypoxic tumors.

A VDAC1-mediated NEET protein chain transfers [2Fe-2S] clusters between the mitochondria and the cytosol and impacts mitochondrial dynamics.

Mitochondrial inner NEET (MiNT) and the outer mitochondrial membrane (OMM) mitoNEET (mNT) proteins belong to the NEET protein family. This family plays a key role in mitochondrial labile iron and reactive oxygen species (ROS) homeostasis. NEET proteins contain labile [2Fe-2S] clusters which can be transferred to apo-acceptor proteins. In eukaryotes, the biogenesis of [2Fe-2S] clusters occurs within the mitochondria by the iron-sulfur cluster (ISC) system; the clusters are then transferred to [2Fe-2S] proteins within the mitochondria or exported to cytosolic proteins and the cytosolic iron-sulfur cluster assembly (CIA) system. The last step of export of the [2Fe-2S] is not yet fully characterized. Here we show that MiNT interacts with voltage-dependent anion channel 1 (VDAC1), a major OMM protein that connects the intermembrane space with the cytosol and participates in regulating the levels of different ions including mitochondrial labile iron (mLI). We further show that VDAC1 is mediating the interaction between MiNT and mNT, in which MiNT transfers its [2Fe-2S] clusters from inside the mitochondria to mNT that is facing the cytosol. This MiNT-VDAC1-mNT interaction is shown both experimentally and by computational calculations. Additionally, we show that modifying MiNT expression in breast cancer cells affects the dynamics of mitochondrial structure and morphology, mitochondrial function, and breast cancer tumor growth. Our findings reveal a pathway for the transfer of [2Fe-2S] clusters, which are assembled inside the mitochondria, to the cytosol.

Genetic analysis of cancer drivers reveals cohesin and CTCF as suppressors of PD-L1.

Immune evasion is a significant contributor to tumor evolution, and the immunoinhibitory axis PD-1/PD-L1 is a frequent mechanism employed to escape tumor immune surveillance. To identify cancer drivers involved in immune evasion, we performed a CRISPR-Cas9 screen of tumor suppressor genes regulating the basal and interferon (IFN)-inducible cell surface levels of PD-L1. Multiple regulators of PD-L1 were identified, including IRF2, ARID2, KMT2D, and AAMP. We also identified CTCF and the cohesin complex proteins, known regulators of chromatin architecture and transcription, among the most potent negative regulators of PD-L1 cell surface expression. Additionally, loss of the cohesin subunit RAD21 was shown to up-regulate PD-L2 and MHC-I surface expression. PD-L1 and MHC-I suppression by cohesin were shown to be conserved in mammary epithelial and myeloid cells. Comprehensive examination of the transcriptional effect of STAG2 deficiency in epithelial and myeloid cells revealed an activation of strong IFN and NF-κB expression signatures. Inhibition of JAK-STAT or NF-κB pathways did not result in rescue of PD-L1 up-regulation in RAD21-deficient cells, suggesting more complex or combinatorial mechanisms at play. Discovery of the PD-L1 and IFN up-regulation in cohesin-mutant cells expands our understanding of the biology of cohesin-deficient cells as well as molecular regulation of the PD-L1 molecule.

Myricetin inhibits interferon-γ-induced PD-L1 and IDO1 expression in lung cancer cells.

Programmed death ligand-1 (PD-L1) and indoleamine 2, 3-dioxygenase 1 (IDO1) are immune checkpoints induced by interferon-γ (IFN-γ) in the tumor microenvironment, leading to immune escape of tumors. Myricetin (MY) is a flavonoid distributed in many edible and medicinal plants. In this study, MY was identified to inhibit IFN-γ-induced PD-L1 expression in human lung cancer cells. It also reduced the expression of IDO1 and the production of kynurenine which is the product catalyzed by IDO1, while didn't show obvious effect on the expression of major histocompatibility complex-I (MHC-I), a crucial molecule for antigen presentation. In addition, the function of T cells was evaluated using a co-culture system consist of lung cancer cells and the Jurkat-PD-1 T cell line overexpressing PD-1. MY restored the survival, proliferation, CD69 expression and interleukin-2 (IL-2) secretion of Jurkat-PD-1 T cells suppressed by IFN-γ-treated lung cancer cells. Mechanistically, IFN-γ up-regulated PD-L1 and IDO1 at the transcriptional level through the JAK-STAT-IRF1 axis, which was targeted and inhibited by MY. Together, our research revealed a new mechanism of MY mediated anti-tumor activity and highlighted the potential implications of MY in tumor immunotherapy.

Prediction and validation of GUCA2B as the hub-gene in colorectal cancer based on co-expression network analysis: In-silico and in-vivo study.

BACKGROUND: Several serious attempts to treat colorectal cancer have been made in recent decades. However, no effective treatment has yet been discovered due to the complexities of its etiology. METHODS: we used Weighted Gene Co-expression Network Analysis (WGCNA) to identify key modules, hub-genes, and mRNA-miRNA regulatory networks associated with CRC. Next, enrichment analysis of modules has been performed using Cluepedia. Next, quantitative real-time PCR (RT-qPCR) was used to validate the expression of selected hub-genes in CRC tissues. RESULTS: Based on the WGCNA results, the brown module had a significant positive correlation (r = 0.98, p-value=9e-07) with CRC. Using the survival and DEGs analyses, 22 genes were identified as hub-genes. Next, three candidate hub-genes were selected for RT-qPCR validation, and 22 pairs of cancerous and non-cancerous tissues were collected from CRC patients referred to the Gastroenterology and Liver Clinic. The RT-qPCR results revealed that the expression of GUCA2B was significantly reduced in CRC tissues, which is consistent with the results of differential expression analysis. Finally, top miRNAs correlated with GUCA2B were identified, and ROC analyses revealed that GUCA2B has a high diagnostic performance for CRC. CONCLUSIONS: The current study discovered key modules and GUCA2B as a hub-gene associated with CRC, providing references to understand the pathogenesis and be considered a novel candidate to CRC target therapy.

Sp1 Plays a Key Role in Vasculogenic Mimicry of Human Prostate Cancer Cells.

Sp1 transcription factor regulates genes involved in various phenomena of tumor progression. Vasculogenic mimicry (VM) is the alternative neovascularization by aggressive tumor cells. However, there is no evidence of the relationship between Sp1 and VM. This study investigated whether and how Sp1 plays a crucial role in the process of VM in human prostate cancer (PCa) cell lines, PC-3 and DU145. A cell viability assay and three-dimensional culture VM tube formation assay were performed. Protein and mRNA expression levels were detected by Western blot and reverse transcriptase-polymerase chain reaction, respectively. The nuclear twist expression was observed by immunofluorescence assay. A co-immunoprecipitation assay was performed. Mithramycin A (MiA) and Sp1 siRNA significantly decreased serum-induced VM, whereas Sp1 overexpression caused a significant induction of VM. Serum-upregulated vascular endothelial cadherin (VE-cadherin) protein and mRNA expression levels were decreased after MiA treatment or Sp1 silencing. The protein expression and the nuclear localization of twist were increased by serum, which was effectively inhibited after MiA treatment or Sp1 silencing. The interaction between Sp1 and twist was reduced by MiA. On the contrary, Sp1 overexpression enhanced VE-cadherin and twist expressions. Serum phosphorylated AKT and raised matrix metalloproteinase-2 (MMP-2) and laminin subunit 5 gamma-2 (LAMC2) expressions. MiA or Sp1 silencing impaired these effects. However, Sp1 overexpression upregulated phosphor-AKT, MMP-2 and LAMC2 expressions. Serum-upregulated Sp1 was significantly reduced by an AKT inhibitor, wortmannin. These results demonstrate that Sp1 mediates VM formation through interacting with the twist/VE-cadherin/AKT pathway in human PCa cells.

Lysophosphatidic Acid Promotes the Expansion of Cancer Stem Cells via TRPC3 Channels in Triple-Negative Breast Cancer.

Triple-negative breast cancer (TNBC) is a highly aggressive cancer for which targeted therapeutic agents are limited. Growing evidence suggests that TNBC originates from breast cancer stem cells (BCSCs), and elucidation of the molecular mechanisms controlling BCSC proliferation will be crucial for new drug development. We have previously reported that the lysosphingolipid sphingosine-1-phosphate mediates the CSC phenotype, which can be identified as the ALDH-positive cell population in several types of human cancer cell lines. In this study, we have investigated additional lipid receptors upregulated in BCSCs. We found that lysophosphatidic acid (LPA) receptor 3 was highly expressed in ALDH-positive TNBC cells. The LPAR3 antagonist inhibited the increase in ALDH-positive cells after LPA treatment. Mechanistically, the LPA-induced increase in ALDH-positive cells was dependent on intracellular calcium ion (Ca2+), and the increase in Ca2+ was suppressed by a selective inhibitor of transient receptor potential cation channel subfamily C member 3 (TRPC3). Moreover, IL-8 production was involved in the LPA response via the activation of the Ca2+-dependent transcriptional factor nuclear factor of activated T cells. Taken together, our findings provide new insights into the lipid-mediated regulation of BCSCs via the LPA-TRPC3 signaling axis and suggest several potential therapeutic targets for TNBC.

Fatty Acid Binding Protein 6 Inhibition Decreases Cell Cycle Progression, Migration and Autophagy in Bladder Cancers.

Bladder cancer (BC) has a high recurrence rate worldwide. The aim of this study was to evaluate the role of fatty acid binding protein 6 (FABP6) in proliferation and migration in human bladder cancer cells. Cell growth was confirmed by MTT and colony formation assay. Western blotting was used to explore protein expressions. Wound healing and Transwell assays were performed to evaluate the migration ability. A xenograft animal model with subcutaneous implantation of BC cells was generated to confirm the tumor progression. Knockdown of FABP6 reduced cell growth in low-grade TSGH-8301 and high-grade T24 cells. Cell cycle blockade was observed with the decrease of CDK2, CDK4, and Ki67 levels in FABP6-knockdown BC cells. Interestingly, knockdown of FBAP6 led to downregulation of autophagic markers and activation of AKT-mTOR signaling. The application of PI3K/AKT inhibitor decreased cell viability mediated by FABP6-knockdown additionally. Moreover, FABP6-knockdown reduced peroxisome proliferator-activated receptor γ and retinoid X receptor α levels but increased p-p65 expression. Knockdown of FABP6 also inhibited BC cell motility with focal adhesive complex reduction. Finally, shFABP6 combined with cisplatin suppressed tumor growth in vivo. These results provide evidence that FABP6 may be a potential target in BC cells progression.

Zinc Status Impacts the Epidermal Growth Factor Receptor and Downstream Protein Expression in A549 Cells.

Zinc has been suggested to play a role in carcinogenesis and tumor progression. Serum zinc levels of lung cancer patients are for example lower than in healthy individuals. The activation and expression of the epidermal growth factor receptor (EGFR), which plays a role in tumor biology, are presumably influenced by zinc. EGFR activation influences cell adhesion and immune escape. This study provides insights into the impacts of zinc on the EGFR activation and expression of downstream proteins such as E-cadherin and PD-L1 in the alveolar carcinoma cell line A549. To model chronic changes in zinc homeostasis, A549 cells were cultured in media with different zinc contents. EGFR surface expression of unstimulated and stimulated A549 cells was determined by flow cytometry. EGFR phosphorylation as well as the protein expression of E-cadherin and PD-L1 were analyzed by Western blot. In our hands, chronic zinc deficiency led to increased EGFR surface expression, decreased E-cadherin protein expression and increased PD-L1 protein expression. Zinc supplementation decreased EGFR surface expression and PD-L1 protein expression. In summary, zinc-deficient A549 cells may display a more malignant phenotype. Thus, future clinical research should further focus on the possible benefits of restoring disturbed zinc homeostasis, especially in lung cancer patients.

CAF-derived exosomes deliver LINC01410 to promote epithelial-mesenchymal transition of esophageal squamous cell carcinoma.

Exosomes mediate cellular communications in cancer by transmitting active molecules. However, the CAFs-derived molecular determinants that regulate esophageal squamous cell carcinoma (ESCC) metastasis have not been fully characterized. The purpose of this study was to investigate the potential roles of exosomal LINC01410 of ESCC cells. The characteristics of exosomes were identified using transmission electron microscope (TEM), Nanoparticle Tracking Analysis (NTA). The expression of LINC01410 and miR-122-5p was analyzed by quantitative real-time polymerase chain reaction (qRT-PCR) assay. The biological roles of LINC01410 in ESCC cells were investigated using transwell assay. Western blot assay was employed to detect protein levels. The potential downstream molecular mechanism of LINC01410 was demonstrated with dual-luciferase reporter assay, RNA immunoprecipitation (RIP) assay and RNA pull down. CAFs promote the metastasis and epithelial-mesenchymal transition (EMT) of ESCC cells. CAFs exert their roles by transferring exosomes to ESCC cells, leading to a significant increase of LINC01410 level in ESCC cells. Mechanically, LINC01410 secreted by CAFs-Exo could contribute to metastasis and EMT by sponging miR-122-5p and increasing PKM2 level in TE-1 and Eca-109 cells. Additionally, LINC01410/miR-122-5p/PKM2 axis affecting ESCC metastasis and EMT in vitro and in vivo.

The epithelial-mesenchymal transition of glioma cells promotes tissue factor expression via the miR200a/ZEB1 axis.

Glioma is the most common brain tumor and the main cause of death from primary brain tumors. Due to the limitations of current diagnostic and treatment methods, the prognosis of high-grade glioma is not optimistic and is prone to venous thrombosis. Epithelial-mesenchymal transition (EMT) is a vital step for glioma cells to obtain a highly migratory and invasive cell phenotype. Tissue factor (TF) is the downstream target of several carcinogenic pathways. According to reports, the TF gene is highly methylated and down-regulated in IDH1 mutant gliomas with good prognosis. We aimed to investigate the impact of EMT on the expression of TF in glioma cells, as well as the corresponding mechanism. Our data indicated that the expression level of TF in glioma tissues increased, and was positively correlated with the WHO classification of glioma. After inducing EMT in glioma cells in vitro, TF expression increased significantly, indicating that EMT in glioma cells can promote TF expression. Further studies have shown that the expression level of ZEB1 is positively correlated with the WHO classification of glioma tissues and the expression level of TF in glioma tissues. This study proved that EMT promotes the expression of TF in glioma cells through the miR-200a/ZEB1 axis. In summary, these results indicated that EMT can promote the expression of TF in glioma cells via the miR-200a/ZEB1 axis. For gliomas, TF is related to EMT and has the potential to become an effective target against EMT and thrombotic events.

m6A regulator-mediated methylation modification patterns and tumor immune microenvironment in sarcoma.

BACKGROUND: Studies have shown that the RNA N6-methyladenosine (m6A) modification patterns are extensively involved in the development of multiple tumors. However, the association between the m6A regulator expression patterns and the sarcoma tumor immune microenvironment (TIME) remains unclear. METHODS: We systematically evaluated the m6A regulator expression patterns in patients with sarcoma based on known 23 m6A regulators. Different m6A regulator expression patterns were analyzed using gene set variation analysis and a single-sample gene set enrichment analysis algorithm. According to the results of consensus clustering, we classified the patients into four different clusters. Next, we subjected the four clusters to differential genetic analysis and established m6A-related differentially expressed genes (DEGs). We then calculated the m6A-related DEGs score and constructed the m6A-related gene signature, named m6A score. Finally, the 259 sarcoma samples were divided into high- and low-m6A score groups. We further evaluated the TIME landscape between the high- and low-m6A score groups. RESULTS: We identified four different m6A modification clusters and found that each cluster had unique metabolic and immunological characteristics. Based on the 19 prognosis-related DEGs, we calculated the principal component analysis scores for each patient with sarcoma and classified them into high- and low-m6A score groups. CONCLUSIONS: The m6A regulator expression patterns and complexity of the sarcoma TIME landscape are closely related to each other. Systematic evaluation of m6A regulator expression patterns and m6A scores in patients with sarcoma will enhance our understanding of TIME characteristics.

SNHG8 promotes cell proliferation, migration, and invasion of nasopharyngeal carcinoma cells as an oncogene through miR-588/HMGA2 axis.

Nasopharyngeal carcinoma (NC) poses a threat to the life of patients. Long non-coding RNA (LncRNA) is a novel kind of non-coding RNA, which plays a pivotal role through sponge microRNA (miRNA). Abnormal expression of small nucleolar RNA host gene 8 (SNHG8) is involved in various tumors; however, the role of SNHG8 in NC remains unknown. Quantitative real-time PCR (qRT-PCR) and Western blotting was employed to detect the expression levels of SNHG8, miR-588, and high mobility group A2 (HMGA2). Cell proliferation, migration, and invasion were analyzed by CCK-8 and transwell assays. miR-588 binding sites in SNHG8 were predicted by LncBase analysis. Luciferase reporter and RNA pull-down assay were used to confirm the interaction of SNHG8 and miR-588. SNHG8 was highly expressed in NC cells. The prognosis of the patients with NC in the high expression levels of SNHG8 was poorer than that in the low expression levels. The expression of SNHG8 was closely related to tumor size, TNM stage, and distal metastasis. Knockdown of SNHG8 inhibited cell proliferation, migration, and invasion of NC. SNHG8 targeted miR-588. Inhibition of miR-588 could partially reverse the knockdown of SNHG8 in NC cells, and miR-588 targeted HMGA2. In conclusion, SNHG8 promotes proliferation, migration, and invasion of NC cells through miR-588/HMGA2 in NC as an oncogene.

LINC02362 attenuates hepatocellular carcinoma progression through the miR-516b-5p/SOSC2 axis.

Hepatocellular carcinoma (HCC) is one of the most death-related cancers worldwide. Identifying cancer-associated genes and uncovering the vital molecular mechanisms of HCC progression contribute greatly to the prognosis and novel therapeutic strategies for HCC patients. Although lncRNAs have been proved to be critical modulators of various cellular processes, the functions of lncRNAs in HCC progression are just emerging. Here, we found that a long non-coding RNA (lncRNA) named LINC02362, whose biological effects have yet been unveiled in cancers, was associated with a better prognosis in patients with HCC. Gain-of-function analyses showed that LINC02362 inhibited the survival, migration, invasion and epithelial-to-mesenchymal transition (EMT) of HCC cells. Moreover, miR-516b-5p was enriched as a target of LINC02362, which functioned as a sponge to regulate the endogenous levels of miR-516b-5p. Furthermore, we confirmed that SOSC2 served as a downstream target gene which was negatively controlled by miR-516b-5p. Importantly, a series of rescue experiments indicated that the tumor-suppressive effects of LINC02362 were achieved through the modulation of the miR-516b-5p/SOSC2 axis. In summary, we identified LINC02362 as a candidate tumor-inhibitory lncRNA that might serve as a biomarker for the prognosis of HCC and a promising therapeutic agent for patients with HCC.

Kruppel-like factor 2 acts as a tumor suppressor in human retinoblastoma.

Krüppel-like factor 2 (KLF2) belongs to the KLF family of zinc-finger transcription factors and mediates the occurrence and progression of various cancers. However, little is known about its expression pattern and biological role in retinoblastoma (RB). In the present study, we showed that KLF2 was markedly downregulated in human RB tissue compared with retina. KLF2 overexpression significantly inhibited RB cell proliferation and decreased proliferating cell nuclear antigen (PCNA) expression. Subsequently, we confirmed that KLF2 arrested cells at the G1-S phase transition, accompanied by the upregulation of p21 and downregulation of CyclinD1, as well as the activation of mitochondria-mediated apoptosis in RB cells. In addition, KLF2 overexpression contributed to suppressing RB cell migration and invasion by downregulating matrix metallopeptidase 9 (MMP9). On the contrary, KLF2 downregulation promoted RB cells proliferation, migration and invasion. Notably, the KLF2 expression pattern was opposite to that of C-X-C chemokine receptor 4 (CXCR4) in the two RB cell lines, KLF2 overexpression significantly decreased CXCR4 expression, silencing KLF2 had the opposite effect. Furthermore, dual-luciferase reporter and chromatin immunoprecipitation (ChIP) assays confirmed that KLF2 directly bound to the CXCR4 promoter and negatively regulated its expression in RB cells. Collectively, our results suggested that KLF2 function as a tumor suppressor in RB and may represent a potential therapeutic target for RB.

Panax notoginseng saponins induce apoptosis in retinoblastoma Y79 cells via the PI3K/AKT signalling pathway.

This study aimed to investigate the effects of Panax notoginseng saponins (PNS) on the proliferation, apoptosis, and PI3K/AKT signalling pathways of retinoblastoma Y79 cells to explore the possible mechanism of action of PNS on retinoblastoma. The effects of PNS and carboplatin on the proliferation of Y79 cells were examined using cell counting kit-8 assay. And the apoptosis rate, the mRNA and protein levels of apoptosis-related genes and the expression of PI3K/AKT pathway protein were assessed. PNS effectively inhibited the proliferation (P < 0.05) and increased apoptosis of Y79 cells (P < 0.05). Compared with the negative control, the Y79 cells treated with PNS had significantly increased (P < 0.05) mRNA and protein expression of Bax, caspase-3, caspase-8, and caspase-9 and elevated levels of cleaved caspase-3, cleaved caspase-8, and cleaved caspase-9 proteins (P < 0.05). The mRNA and protein expression of the apoptosis suppressor gene Bcl-2 was inhibited (P < 0.05), while the Bax/Bcl-2 values of the cells in the drug group were significantly higher than those in the negative group (P < 0.01). After treatment with PNS, the total protein expression of PI3K and AKT1 in the Y79 cells did not show significant differences compared with the negative group (P > 0.05), although the expression of phosphorylated proteins p-PI3K, p-AKT (Thr308), p-AKT (Ser473), and p-mTOR were significantly reduced (P < 0.05). Meanwhile, the antagonist protein of the pathway phosphatase and tensin homologue deleted on chromosome 10 (PTEN) expression was increased (P < 0.01). Cellular alterations following inhibition of the PI3K/AKT pathway using LY294002 were similar to those of PNS, the proliferation of Y79 cells was also inhibited, and cell apoptosis increased (P < 0.001). The expression of Bax, caspase-3, caspase-8, caspase-9, and activation proteins cleaved caspase-3, cleaved caspase-8, and cleaved caspase-9 was also significantly higher than that in the negative control (P < 0.05). Bcl-2 protein expression was decreased (P < 0.01), and the Bax/Bcl-2 ratio was higher than that in the negative control (P < 0.001). Overall, we demonstrated that PNS effectively inhibited the proliferation and promoted the apoptosis of retinoblastoma Y79 cells. The apoptosis-promoting effect of PNS may involve the inhibition of the PI3K/AKT signalling pathway, which subsequently regulates the expression of apoptosis-related genes.

Cisplatin resistance of NSCLC cells involves upregulation of visfatin through activation of its transcription and stabilization of mRNA.

Non-small cell lung cancer (NSCLC) is one of the prevalent and deadly cancers worldwide. Cisplatin (CDDP) has been used as a standard adjuvant therapy for advanced NSCLC patients, while chemoresistance is one of the most challenging problems to limit its clinical application. Our data showed that the expression of visfatin was significantly increased in CDDP resistant NSCLC cells as compared with that in their parental cells, while knockdown of visfatin or its neutralization antibody can restore the CDDP sensitivity of resistant NSCLC cells. The upregulation of visfatin in CDDP resistant NSCLC cells was due to the increased mRNA stability and promoter activity. Further, we found that signal transducer and activator of transcription 3 (STAT3), which was increased in chemoresistant cells, can increase the transcription of visfatin. While tristetraprolin (TTP), which can decease mRNA stability of visfatin, was decreased in chemoresistant cells. Inhibition of STAT3 or over expression of TTP can restore CDDP sensitivity of resistant NSCLC cells. Collectively, our data showed that STAT3 and TTP-regulated expression of visfatin was involved in CDDP resistance of NSCLC cells. It indicated that targeted inhibition of visfatin should be a potential approach to overcome CDDP resistance of NSCLC treatment.

Fructose-1,6-bisphosphatase 2 represses cervical cancer progression via inhibiting aerobic glycolysis through promoting pyruvate kinase isozyme type M2 ubiquitination.

Growing evidence has shown that aerobic glycolysis, as a hallmark of cancer cells, plays a crucial role in cervical cancer. The aim of the study is to uncover whether fructose-1,6-bisphosphatase 2 (FBP2) is involved in cervical cancer progression via the aerobic glycolysis pathway. FBP2 levels were determined by quantitative PCR (qPCR) and western blotting. Cell growth viability and apoptosis were tested by cell counting kit-8 (CCK-8) and flow cytometry assays. Immunoprecipitation assay was applied for the detection of the FBP2 effect on pyruvate kinase isozyme type M2 (PKM2) ubiquitination. FBP2 level was decreased in cervical cancer, which is closely linked to shorter overall survival. FBP2 decreased cell growth and aerobic glycolysis and increased cell apoptosis, as well as decreased PKM2 expression and increased its ubiquitination level. The above-mentioned roles of FBP2 were weakened followed by PKM2 overexpression. FBP2 inhibited cervical cancer cell growth via inhibiting aerobic glycolysis by inducing PKM2 ubiquitination.

Hsp90 regulates the tumorigenic function of tyrosine protein kinase in osteosarcoma.

Despite recent advances in diagnosis and treatment, osteosarcoma remains as the most common bone cancer in children and is associated with poor prognosis. Growing evidence has supported dysregulation of threonine and tyrosine protein kinase (TTK) expression as a hallmark of multiple cancers, however, its function in osteosarcoma remains to be elucidated. In the present study, we found that TTK was frequently overexpressed in osteosarcoma and associated with increased tumour growth and progression. Moreover, using both in vitro and in vivo assays, we provided evidence that TTK level was regulated by a molecular chaperone, heat shock protein 90 (Hsp90). Hsp90 directly interacted with TTK and prevents proteasome-dependent TTK degradation, leading to the accumulation of TTK in osteosarcoma cells. Elevated TTK promoted cancer cell proliferation and survival by activating cell-cycle progression and inhibiting apoptosis. Consistently, depletion of TTK by Hsp90 inhibition induced cell-cycle arrest, generated aneuploidy and eventually resulted in apoptotic cancer cell death. Together, our study revealed an important Hsp90-TTK regulatory axis in osteosarcoma cells to promote cancer cell growth and survival. These findings expand our knowledge on osteosarcoma pathogenesis and offer novel therapeutic options for clinical practice.