LINC00618 facilitates growth and metastasis of hepatocellular carcinoma via elevating cholesterol synthesis by promoting NSUN2-mediated SREBP2 m5C modification.

Dysregulation of cholesterol metabolism is an important feature of cancer development. There are limited reports on the involvement of lncRNAs in hepatocellular carcinoma (HCC) progression via the cholesterol metabolism pathway. The present study explored the effect of LINC00618 on HCC growth and metastasis, and elucidated the underlying mechanisms involved in cholesterol metabolism. Here, we found that LINC00618 expression was upregulated in cancerous tissues from 30 patients with HCC compared to that in adjacent normal tissues. High expression of LINC00618 was detected in metastatic HCC tissues. LINC00618 is predominantly localized in the nucleus and overexpression of LINC00618 facilitated HCC cell proliferation, migration and EMT progression by promoting cholesterol biosynthesis. Mechanistically, the 1-101nt region of LINC00618 bound to NSUN2. LINC00618 inhibited ubiquitin-proteasome pathway-induced NSUN2 degradation. NSUN2 stabilized by LINC00618 increased m5C modification of SREBP2 and promoted SREBP2 mRNA stability in a YBX1-dependent manner, thereby promoting cholesterol biosynthesis in HCC cells. Moreover, mouse HCC xenograft and lung metastasis models were established by subcutaneous and tail vein injections of MHCC97 cells transfected with or without sh-LINC00618. Silencing LINC00618 impeded HCC growth and metastasis. In conclusion, LINC00618 promoted HCC growth and metastasis by elevating cholesterol synthesis by stabilizing NSUN2 to enhance SREBP2 mRNA stability in an m5C-dependent manner.

SNHG1, interacting with SND1, contributes to sorafenib resistance of liver cancer cells by increasing m6A-mediated SLC7A11 expression and promoting aerobic glycolysis.

Aerobic glycolysis plays an important role in multidrug resistance of cancer cells. Here, we screened different expressed lncRNAs associated with sorafenib resistance of liver cancer cells, by intersecting the bioinformatics analyses of TCGA and GEO (the GSE62813 dataset) databases. Our results revealed that the 18 upregulated lncRNAs in the intersection are associated with and enriched in metabolism of small molecule organic acids, suggesting their potential in glycolysis. The lncRNA small nucleolar RNA host gene 1 (Snhg1) was chosen as a potential regulator of aerobic glycolysis in liver cancer cells, for its significant promotion on lactate production. Gain- and loss-of-function experiments mediated by Crispr-Cas9 technique in HepG2 cells indicated that Snhg1 promoted cell proliferation, invasion, sorafenib resistance, and aerobic glycolysis. In the mechanism exploration, we found that Snhg1 can interact with SND1 protein, a famous RNA binding protein and recently identified "Reader" of N6-methyladenosine (m6A). SND1 was demonstrated to be positively regulated by Snhg1 and had similar promoting effects on proliferation, invasion, sorafenib resistance, and aerobic glycolysis of HepG2 cells. SND1 bound with and promoted the expression of SLC7A11, an aerobic glycolysis regulator. Furthermore, either silencing SLC7A11 or blocking aerobic glycolysis with 2-deoxy-d-glucose (2-DG) was able to reverse the promotion of Snhg1 overexpression on malignancy, sorafenib resistance, and aerobic glycolysis of HepG2 cells. Finally, in a liver cancer xenograft mouse model, we found that formed tumors with Snhg1-knocked-down HepG2 cells were more sensitive to sorafenib administration. Altogether, SNHG1 contributes to sorafenib resistance of liver cancer cells by promoting SND1-m6A-SLC7A11-mediated aerobic glycolysis.

LncRNA-p21 suppresses cell proliferation and induces apoptosis in gastric cancer by sponging miR-514b-3p and up-regulating ARHGEF9 expression.

The long non-coding RNA p21 (lncRNA-p21) was a tumor suppressor gene in most cancer types including gastric cancer (GC). We aimed to identify a specific lncRNA-p21-involved pathway in regulating the proliferation and apoptosis of GC cells. A lower lncRNA-p21 expression in tumors was associated with advanced disease stage and predicted worse survival of GC patients. LncRNA-p21 overexpression in GC cell line somatic gastric cancer (SGC)-7901 and human gastric cancer (HGC)-27 suppressed cell proliferation and enhanced apoptosis, while lncRNA-p21 knockdown caused the opposite effects. Through bioinformatics analysis and luciferase-based reporter assays, we identified miR-514b-3p as a sponge target of lncRNA-p21. Cdc42 guanine nucleotide exchange factor 9 (ARHGEF9), functioned as a tumor suppress factor in GC, was found as the downstream target of miR-514-3p, and their expressions were negatively correlated in GC tumor tissues. In addition, like lncRNA-p21 overexpression alone, miR-514-3p inactivation alone also led to decreased proliferation and increased apoptosis in SGC-7901 and HGC-27 cells, which were markedly attenuated by additional ARHGEF9 knockdown. Xenograft SGC-7901 cells with more lncRNA-p21 or ARHGEF9 expressions or with less miR-514-3p expression exhibited obviously slower in vivo growth than the control SGC-7901 cells in nude mice. Our study reveals a novel lncRNA-p21/miR-514b-3p/ARHGEF9 pathway that can be targeted for GC therapy.

Epithelial-mesenchymal transition induced cancer-stem-cell-like characteristics in hepatocellular carcinoma.

Hepatocellular carcinoma in China accounts for half of the world's incidence. Both epithelial-mesenchymal transition (EMT) and cancer stem cells (CSCs) are thought to be involved in tumor malignant progression. However, the relationship between EMT and CSCs is still unclear. Bioinformatics analysis was performed to evaluate the relationship between EMT and CSCs. The EMT and CSC regulatory mechanism was investigated through Transwell, wound-healing, sphere formation, colony-forming, and western blotting assays. Immunofluorescence and immunoprecipitation were used to study the interaction of hypoxia inducible factor 1α (HIF-1α) /Notch1. Immunohistochemical study was applied to investigate the expression pattern in the process of hepatocellular carcinogenesis and development. In our present study, bioinformatics results indicate that the expression of EMT-related molecules is correlated with CSCs. In vitro studies indicated that EMT activation could induce CSC characteristics. Notch1 was confirmed to mediate the process of EMT-induced CSCs through the interaction with HIF-1α directly. Our findings indicate that EMT could induce CSC-like characteristics, which is mediated by HIF-1α-upregulated Notch intracellular domain expression.

microRNA-219-5p inhibits epithelial-mesenchymal transition and metastasis of colorectal cancer by targeting lymphoid enhancer-binding factor 1.

Aberrant expression of microRNAs (miRs) has been shown to play a critical role in the pathogenesis and progression of tumors. microRNA-219-5p (miR-219-5p) has been reported to be abnormally expressed in some types of human tumors. However, the mechanism between miR-219-5p and colorectal cancer (CRC) metastasis remains unclear. In the present study, miR-219-5p was found to be downregulated in CRC tissue compared with matched normal tissue. Through luciferase reporter assay, we demonstrated lymphoid enhancer-binding factor 1 (LEF1) as a direct target of miR-219-5p. Overexpression of miR-219-5p could inhibit motility, migration and invasion of CRC cells, and inhibit epithelial-mesenchymal transition (EMT). Furthermore, silencing LEF1 phenocopied this metastasis-suppressive function. The recovery experiment showed that re-expression of LEF1 rescued this suppressive effect on tumor metastasis and reversed the expression of EMT markers caused by miR-219-5p. Additionally, we demonstrated that miR-219-5p exerted this tumor-suppressive function by blocking activation of the AKT and ERK pathways. Finally, a nude mice experiment showed that miR-219-5p reduced the lung metastasis ability of CRC cells. Taken together, our findings indicate that miR-219-5p inhibits metastasis and EMT of CRC by targeting LEF1 and suppressing the AKT and ERK pathways, which may provide a new antitumor strategy to delay CRC metastasis.

Anti-Inflammatory Terpenoids from the Rhizomes of Shell Ginger.

Shell ginger (Alpinia zerumbet) is a perennial ornamental plant of ginger native to East Asia, which can be used as a flavoring agent in food or beverage, as well as a traditional Chinese medicine. In this study, a total of 37 terpenoids, including 7 new compounds, zerumin D1 to zerumin D7 (2, 3, 28-30, 36, and 37), and 5 new naturally occurring compounds, zerumin D10 to zerumin D14 (9, 12, 15, 20, and 24), were isolated and identified from the rhizomes of shell ginger. Compound 3 was an unprecedented variant labdane diterpenoid featuring a unique 6/7/6/3 tetracyclic cyclic ether system in its side chain. The anti-inflammatory activities of the isolated terpenoids were assessed in RAW 264.7 macrophages stimulated by lipopolysaccharide (LPS). Compound 4 significantly inhibited the production of nitric oxide with an IC50 value of 5.4 µM. Further investigation revealed that compounds 2 and 3 may inhibit the nuclear translocation of NF-κB, thus suppressing the expression of IL-6, IL-1ß, iNOS, and COX-2 to exert the anti-inflammatory effects.

Polycomb complex protein BMI-1 promotes invasion and metastasis of pancreatic cancer stem cells by activating PI3K/AKT signaling, an ex vivo, in vitro, and in vivo study.

Cancer stem cell theory indicates cancer stem cells are the key to promote tumor invasion and metastasis. Studies showed that BMI-1 could promote self-renew, differentiation and tumor formation of CSCs and invasion/metastasis of human cancer. However, whether BMI-1 could regulate invasion and metastasis ability of CSCs is still unclear. In our study, we found that up-regulated expression of BMI-1 was associated with tumor invasion, metastasis and poor survival of pancreatic cancer patients. CD133+ cells were obtained by using magnetic cell sorting and identified of CSCs properties such as self-renew, multi-differentiation and tumor formation ability. Then, we found that BMI-1 expression was up-regulated in pancreatic cancer stem cells. Knockdown of BMI-1 expression attenuated invasion ability of pancreatic cancer stem cells in Transwell system and liver metastasis capacity in nude mice which were injected CSCs through the caudal vein. We are the first to reveal that BMI-1 could promote invasion and metastasis ability of pancreatic cancer stem cells. Finally, we identified that BMI-1 expression activating PI3K/AKT singing pathway by negative regulating PTEN was the main mechanism of promoting invasion and metastasis ability of pancreatic CSCs. In summary, our findings indicate that BMI-1 could be used as the therapeutic target to inhibiting CSCs-mediated pancreatic cancer metastasis.