Identification of SRGAP2 as a potential oncogene and a prognostic biomarker in hepatocellular carcinoma

Ganoderma lucidum (Curtis) P. Karst. Immunomodulatory Protein Has the Potential to Improve the Prognosis of Breast Cancer Through the Regulation of Key Prognosis-Related Genes

Background/Objectives: Breast cancer in women is the most commonly diagnosed and most malignant tumor. Although luminal A breast cancer (LumA) has a relatively better prognosis, it still has a persistent pattern of recurrence. Ganoderma lucidum (Curtis) P. Karst. is a kind of traditional Chinese medicine and has antitumor effects. In this study, we aimed to identify the genes relevant to prognosis, find novel targets, and investigate the function of the bioactive protein from G. lucidum, called FIP-glu, in improving prognosis. Methods: Gene expression data and clinical information of LumA breast cancer patients were downloaded from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. Using bioinformatics methods, a predictive risk model was constructed to predict the prognosis for each patient. The cell counting kit-8 (CCK8) and clone formation assays were used to validate gene function. The ability of FIP-glu to regulate RNA levels of risk genes was validated. Results: Six risk genes (slit-roundabout GTPase-activating protein 2 (SRGAP2), solute carrier family 35 member 2 (SLC35A2), sequence similarity 114 member A1 (FAM114A1), tumor protein P53-inducible protein 11 (TP53I11), transmembrane protein 63C (TMEM63C), and polymeric immunoglobulin receptor (PIGR)) were identified, and a prognostic model was constructed. The prognosis was worse in the high-risk group and better in the low-risk group. The receiver operating characteristic (ROC) curve confirmed the model's accuracy. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses showed that the differentially expressed genes (DEGs) between the high- and low-risk groups were significantly enriched in the immune responses. TMEM63C could promote tumor viability, growth, and proliferation in vitro. FIP-glu significantly regulated these risk genes, and attenuated the promoting effect of TMEM63C in breast cancer cells. Conclusions: SRGAP2, SLC35A2, FAM114A1, TP53I11, TMEM63C, and PIGR were identified as the potential risk genes for predicting the prognosis of patients. TMEM63C could be a potential novel therapeutic target. Moreover, FIP-glu was a promising drug for improving the prognosis of LumA breast cancer.

Differential Expression of MicroRNA MiR-145 and MiR-155 Downstream Targets in Oral Cancers Exhibiting Limited Chemotherapy Resistance

New evidence has suggested that non-coding microRNAs play a significant role in mediating and modulating chemotherapy resistance, particularly among oral cancers. One recent study found that the upregulation of miR-145 and the downregulation of miR-155 strongly correlated with a limited chemotherapy resistance to Cisplatin, 5-Fluorouracil, and Paclitaxel, although the mechanism(s) responsible for these observations remain unidentified. Using commercially available cell lines of oral squamous cell carcinoma, RNA was isolated, converted into cDNA, and subsequently screened for the expression of downstream targets of miR-145 and miR-155 using qPCR. These results demonstrated the upregulation of miR-21, miR-125, miR-133, miR-365, miR-720, and miR-1246, as well as the downregulation of miR-140, miR-152, miR-218, miR-221, and miR-224. This screening also confirmed the differential expression and regulation of mir-145 and miR-155 among the cell lines with limited chemotherapy resistance (SCC15). In addition, several downstream targets of these specific microRNAs were upregulated by all oral cancer cell lines, such as MBTD1 and FSCN1, or downregulated in all cell lines, such as CLCN3, FLI-1, MRTFB, DAB, SRGAP1, and ABHD17C. However, three miR-145 downstream targets were identified in the least chemotherapy-resistant cells, exhibiting the differential upregulation of KCNA4 and SRGAP2, as well as the downregulation of FAM135A, with this expression pattern not detected in any of the other oral cancer cell lines. These data strongly support that the differential regulation of these three downstream targets may be related to the chemosensitivity of this oral cancer cell line. The potential involvement of these targets must be further investigated to determine how and whether mechanisms of these cellular pathways may be involved in the observed lack of chemotherapy resistance. These data may be important to design targets or treatments to reduce chemotherapy resistance and improve patient treatment outcomes.

Axon guidance molecules in liver pathology: Journeys on a damaged passport

BACKGROUND AND AIMS

The liver is an innervated organ that develops a variety of chronic liver disease (CLD). Axon guidance cues (AGCs), of which ephrins, netrins, semaphorins and slits are the main representative, are secreted or membrane-bound proteins that can attract or repel axons through interactions with their growth cones that contain receptors recognizing these messengers. While fundamentally implicated in the physiological development of the nervous system, the expression of AGCs can also be reinduced under acute or chronic conditions, such as CLD, that necessitate redeployment of neural networks.

METHODS

This review considers the ad hoc literature through the neglected canonical neural function of these proteins that is also applicable to the diseased liver (and not solely their observed parenchymal impact).

RESULTS

AGCs impact fibrosis regulation, immune functions, viral/host interactions, angiogenesis, and cell growth, both at the CLD and HCC levels. Special attention has been paid to distinguishing correlative and causal data in such datasets in order to streamline data interpretation. While hepatic mechanistic insights are to date limited, bioinformatic evidence for the identification of AGCs mRNAs positive cells, protein expression, quantitative regulation, and prognostic data have been provided. Liver-pertinent clinical studies based on the US Clinical Trials database are listed. Future research directions derived from AGC targeting are proposed.

CONCLUSION

This review highlights frequent implication of AGCs in CLD, linking traits of liver disorders and the local autonomic nervous system. Such data should contribute to diversifying current parameters of patient stratification and our understanding of CLD.

Tumor-Derived Exosomal miR-29b Reduces Angiogenesis in Pancreatic Cancer by Silencing ROBO1 and SRGAP2

Background. Exosomal miR-29b reportedly plays a role during cancer metastasis. However, its exact function and underlying mechanism during pancreatic cancer (PC) have not been investigated. Methods. Exosomes from PC cells were prepared and identified. Transmission electron microscopy (TEM) and confocal microscopy were used to examine structural characteristics of the exosomes and verify their internalization by human umbilical vein endothelial cells (HUVECs). The tube formation and migration abilities of HUVECs were detected. VEGF content was assessed by ELISA. GW4869 was used to suppress exosome release. Luciferase reporter assays were performed to verify the predicted interaction of miR-29b with ROBO1 and SRGAP2 mRNA. Results. Exosomal miRNA-29b was differentially expressed in the conditioned medium of PC cells. Exosomes from PC cells were verified by TEM and western blotting. Treatment with the exosomal inhibitor (GW4869) prevented an increase in miR-29b expression and recused the reduced VEGF expression and tube formation and migration abilities of HUVECs cocultured with BxPC3 and AsPC-1 cells that overexpressed miR-29b. Furthermore, the downregulation of ROBO1 and SRGAP2 in cocultured HUVECs was also reduced after additional treatment with GW4869. After incubation with miR-29b exosomes, HUVECs had lower VEGF concentrations and reduced migration and tube formation rates; however, those effects were eliminated by subsequent transfection with the miR-29b inhibitor. Luciferase reporter assays verified the interaction of miR-29b with ROBO1 and SRGAP2. That interaction was also supported by rescue assays showing that overexpression of ROBO1 and SRGAP2 also reduced the antiangiogenic effect of exosomal miR-29b in HUVECs. Conclusion. Exosomal miR-29b originating from PC cells protected HUVECs from PC cell-induced angiogenesis by attenuating ROBO1 and SRGAP2 expression. Our findings suggest a strategy for treating PC.

SRGAP2 controls colorectal cancer chemosensitivity via regulation of mitochondrial complex I activity

Mitochondrial respiration and metabolism play an important role in the occurrence and development of colorectal cancer (CRC). In this study, we identified a functional pool of SLIT-ROBO Rho GTPase-activating protein 2 (SRGAP2) in the mitochondria of CRC cells as an important regulator of CRC chemosensitivity. We found that SRGAP2 levels were increased in CRC cells in comparison to normal colorectal cells. Loss of mitochondrial SRGAP2 led to significant decrease in mitochondrial respiration and strongly sensitized the CRC cells to chemotherapy drugs. Mechanistically, SRGAP2 physically interacts with mitochondrial complex I and positively modulates its activity. In particular, chemosensitization upon SRGAP2 loss was phenocopied by the treatment of complex I inhibitor. Thus, our results demonstrate that SRGAP2 functions as a key regulator of CRC chemosensitivity, identifying SRGAP2 as a promising therapeutic target to enhance the efficacy of chemotherapy in CRC.

Integrated transcriptome and in vitro analysis revealed anti-proliferative effect of sodium perborate on hepatocellular carcinoma cells

BACKGROUND

Hepatocelular carcinoma is one of the leading cancer types with no effective cure as poor prognosis is still a challenging aspect. Thus, alternative therapeutics are necessary to control hepatocelular carcinoma. Boron derivatives such as boric acid (BA), sodium perborate tetrahydrate (SPT) and sodium pentaborate pentahydrate (NaB) have been discovered to have anti-cancer effect. This study investigated the anti-proliferative effects of SPT against hepatocelular carcinoma (HCC) using in vitro and transcriptome approaches.

METHODS

Cytotoxic level of SPT on cell survival were detected using MTS assay. The apoptotic cell death and cell cycle arrest was determined using Annexin V/PI and cell cycle assay, respectively. Transcriptome analysis was performed using RNA-seq, followed by functional and KEGG pathway enrichment analysis. qPCR was used to validate the different genes.

RESULTS

SPT treated HepG2 and Hep3B cells induced cytotoxicity having IC₅₀ values of 1.13 mM and 0.91 mM, respectively. SPT caused mitotic arrest in G₀/G₁ phase at 48 h and subsequent apoptotic cell death. RNA-seq revealed a total number of 822 and 1075 differentially expressed genes (DEGs) which after SPT treatment in HepG2 and Hep3B cells, respectively. Functional and KEGG pathway enrichment results suggested that there are several genes involved to induce apoptosis related pathways. The DEGs in p53 signaling pathway may have closely relationships to the cells apoptosis caused by SPT treatment. qPCR results validated dynamic changes in p53 signaling pathway, DNA replication and cell cycle related genes, such as CDKN1A, SERPINE1, PMAIP1, MCM3, MCM5 and MCM6.

CONCLUSION

In vitro experiments and RNA-seq analysis show anti-proliferative and apoptotic effect of SPT in HCC cells. Further studies might help in understanding the molecular mechanisms of SPT.

The emerging roles of srGAPs in cancer

GTPase activating proteins (GAPs) were initially considered as the inhibitors of cell signaling pathways because of their nature to activate the intrinsic GTPase activity of the RhoGTPases. But recent studies of dysregulated GAPs in many cancers such as glioblastoma, colorectal cancer, breast cancer, and renal cancer have elucidated the important roles of GAPs in carcinogenesis and GAPs have been shown to perform multiple nonconventional functions in different contexts. We have discussed the recent developments in the roles played by different types of srGAPs (SLIT-ROBO Rho GTPase-activating proteins) in cancer.