Metabolic control in cancer cells

LncRNA AC026401.3 interacts with OCT1 to intensify sorafenib and lenvatinib resistance by activating E2F2 signaling in hepatocellular carcinoma

Multitargeted kinase inhibitors (MKIs) including sorafenib and lenvatinib, are applied for first-line treatment for inoperable hepatocellular carcinoma (HCC) patients, but the therapeutic effect is limited because of drug resistance. Therefore, we sought potential biomarkers to indicate sorafenib and lenvatinib resistance in HCC. In this article, we report a novel long non-coding RNA (lncRNA), AC026401.3, in promoting sorafenib and lenvatinib resistance of HCC cells. AC026401.3 is upregulated in HCC tissues and is positively relevant to HCC patients with large tumor size, cancer recurrence, advanced TNM stage, and poor prognosis. AC026401.3 knockdown or knockout enhances the sensitivity of HCC cells to sorafenib and lenvatinib, respectively. Moreover, AC026401.3 upregulates the expression of the transcription factor E2F2. Mechanistically, AC026401.3 interacts with OCT1 and promotes the recruitment of OCT1 to the promoter region of E2F2, intensifying sorafenib and lenvatinib resistance in HCC by activating the transcription of E2F2. In conclusion, our results reveal that lncRNA AC026401.3 is a risk factor for HCC patients by enhancing sorafenib and lenvatinib resistance of HCC cells, and targeting the AC026401.3-OCT1-E2F2 signaling axis would be a promising strategy for HCC therapeutics.

Reprogramming lipid metabolism as potential strategy for hematological malignancy therapy

Hematological malignancies are one of the most lethal illnesses that seriously threaten human life and health. Lipids are important constituents of various biological membranes and substances for energy storage and cell signaling. Furthermore, lipids are critical in the normal physiological activities of cells. In the process of the lethal transformation of hematological malignancies, lipid metabolism reprogramming meets the material and energy requirements of rapidly proliferating and dividing tumor cells. A large number of studies have shown that dysregulated lipid metabolism, commonly occurs in hematological malignancies, mediating the proliferation, growth, migration, invasion, apoptosis, drug resistance and immune escape of tumor cells. Targeting the lipid metabolism pathway of hematological malignancies has become an effective therapeutic approach. This article reviews the oncogenic mechanisms of lipid metabolism reprogramming in hematological malignancies, including fatty acid, cholesterol and phospholipid metabolism, thereby offering an insight into targeting lipid metabolism in the treatment of hematological malignancies.

CDK4: a master regulator of the cell cycle and its role in cancer

The cell cycle is regulated in part by cyclins and their associated serine/threonine cyclin-dependent kinases, or CDKs. CDK4, in conjunction with the D-type cyclins, mediates progression through the G₁ phase when the cell prepares to initiate DNA synthesis. Although Cdk4-null mutant mice are viable and cell proliferation is not significantly affected in vitro due to compensatory roles played by other CDKs, this gene plays a key role in mammalian development and cancer. This review discusses the role that CDK4 plays in cell cycle control, normal development and tumorigenesis as well as the current status and utility of approved small molecule CDK4/6 inhibitors that are currently being used as cancer therapeutics.

Low E2F2 activity is associated with high genomic instability and PARPi resistance

The E2F family, classically known for a central role in cell cycle, has a number of emerging roles in cancer including angiogenesis, metabolic reprogramming, metastasis and DNA repair. E2F1 specifically has been shown to be a critical mediator of DNA repair; however, little is known about DNA repair and other E2F family members. Here we present an integrative bioinformatic and high throughput drug screening study to define the role of E2F2 in maintaining genomic integrity in breast cancer. We utilized in vitro E2F2 ChIP-chip and over expression data to identify transcriptional targets of E2F2. This data was integrated with gene expression from E2F2 knockout tumors in an MMTV-Neu background. Finally, this data was compared to human datasets to identify conserved roles of E2F2 in human breast cancer through the TCGA breast cancer, Cancer Cell Line Encyclopedia, and CancerRx datasets. Through these methods we predict that E2F2 transcriptionally regulates mediators of DNA repair. Our gene expression data supports this hypothesis and low E2F2 activity is associated with a highly unstable tumor. In human breast cancer E2F2, status was also correlated with a patient's response to PARP inhibition therapy. Taken together this manuscript defines a novel role of E2F2 in cancer progression beyond cell cycle and could impact patient treatment.

Integrated TCGA analysis implicates lncRNA CTB-193M12.5 as a prognostic factor in lung adenocarcinoma

Background

Lung cancer is a malignant tumor with the highest incidence and mortality around the world. Recent advances in RNA sequencing technology have enabled insights into long non-coding RNAs (lncRNAs), a previously largely overlooked species in dissecting lung cancer pathology.

Methods

In this study, we used a comprehensive bioinformatics analysis strategy to identify lncRNAs closely associated with lung adenocarcinoma, using the RNA sequencing datasets collected from more than 500 lung adenocarcinoma patients and deposited at The Cancer Genome Atlas (TCGA) database.

Results

Differential expression analysis highlighted lncRNAs CTD-2510F5.4 and CTB-193M12.5, both of which were significantly upregulated in cancerous specimens. Moreover, network analyses showed highly correlated expression levels of both lncRNAs with those of differentially expressed protein-coding genes, and suggested central regulatory roles of both lncRNAs in the gene co-expression network. Importantly, expression of CTB-193M12.5 showed strong negative correlation with patient survival.

Conclusions

Our study mined existing TCGA datasets for novel factors associated with lung adenocarcinoma, and identified a largely unknown lncRNA as a potential prognostic factor. Further investigation is warranted to characterize the roles and significance of CTB-193M12.5 in lung adenocarcinoma biology.

Electronic supplementary material

The online version of this article (10.1186/s12935-018-0513-3) contains supplementary material, which is available to authorized users.

The other side of the coin: the tumor-suppressive aspect of oncogenes and the oncogenic aspect of tumor-suppressive genes, such as those along the CCND-CDK4/6-RB axis

Although cancer-regulatory genes are dichotomized to oncogenes and tumor-suppressor gene s, in reality they can be oncogenic in one situation but tumor-suppressive in another. This dual-function nature, which sometimes hampers our understanding of tumor biology, has several manifestations: (1) Most canonically defined genes have multiple mRNAs, regulatory RNAs, protein isoforms, and posttranslational modifications; (2) Genes may interact at different levels, such as by forming chimeric RNAs or by forming different protein complexes; (3) Increased levels of tumor-suppressive genes in normal cells drive proliferation of cancer progenitor cells in the same organ or tissue by imposing compensatory proliferation pressure, which presents the dual-function nature as a cell-cell interaction. All these manifestations of dual functions can find examples in the genes along the CCND-CDK4/6-RB axis. The dual-function nature also underlies the heterogeneity of cancer cells. Gene-targeting chemotherapies, including that targets CDK4, are effective to some cancer cells but in the meantime may promote growth or progression of some others in the same patient. Redefining "gene" by considering each mRNA, regulatory RNA, protein isoform, and posttranslational modification from the same genomic locus as a "gene" may help in better understanding tumor biology and better selecting targets for different sub-populations of cancer cells in individual patients for personalized therapy.