Effects of siRNA targeting BMPR-II on the biological activities of human liver cancer cells and its mechanism

Recent Advances in RNA Interference-Based Therapy for Hepatocellular Carcinoma: Emphasis on siRNA

Even though RNA treatments were first proposed as a way to change aberrant signaling in cancer, research in this field is currently ongoing. The term "RNAi" refers to the use of several RNAi technologies, including ribozymes, riboswitches, Aptamers, small interfering RNA (siRNA), antisense oligonucleotides (ASOs), and CRISPR/Cas9 technology. The siRNA therapy has already achieved a remarkable feat by revolutionizing the treatment arena of cancers. Unlike small molecules and antibodies, which need administration every three months or even every two years, RNAi may be given every quarter to attain therapeutic results. In order to overcome complex challenges, delivering siRNAs to the targeted tissues and cells effectively and safely and improving the effectiveness of siRNAs in terms of their action, stability, specificity, and potential adverse consequences are required. In this context, the three primary techniques of siRNA therapies for hepatocellular carcinoma (HCC) are accomplished for inhibiting angiogenesis, decreasing cell proliferation, and promoting apoptosis, are discussed in this review. We also deliberate targeting issues, immunogenic reactions to siRNA therapy, and the difficulties with their intrinsic chemistry and transportation.

Prioritization of genes involved in endothelial cell apoptosis by their implication in lymphedema using an analysis of associative gene networks with ANDSystem

BACKGROUND

Currently, more than 150 million people worldwide suffer from lymphedema. It is a chronic progressive disease characterized by high-protein edema of various parts of the body due to defects in lymphatic drainage. Molecular-genetic mechanisms of the disease are still poorly understood. Beginning of a clinical manifestation of primary lymphedema in middle age and the development of secondary lymphedema after treatment of breast cancer can be genetically determined. Disruption of endothelial cell apoptosis can be considered as one of the factors contributing to the development of lymphedema. However, a study of the relationship between genes associated with lymphedema and genes involved in endothelial apoptosis, in the associative gene network was not previously conducted.

METHODS

In the current work, we used well-known methods (ToppGene and Endeavour), as well as methods previously developed by us, to prioritize genes involved in endothelial apoptosis and to find potential participants of molecular-genetic mechanisms of lymphedema among them. Original methods of prioritization took into account the overrepresented Gene Ontology biological processes, the centrality of vertices in the associative gene network, describing the interactions of endothelial apoptosis genes with genes associated with lymphedema, and the association of the analyzed genes with diseases that are comorbid to lymphedema.

RESULTS

An assessment of the quality of prioritization was performed using criteria, which involved an analysis of the enrichment of the top-most priority genes by genes, which are known to have simultaneous interactions with lymphedema and endothelial cell apoptosis, as well as by genes differentially expressed in murine model of lymphedema. In particular, among genes involved in endothelial apoptosis, KDR, TNF, TEK, BMPR2, SERPINE1, IL10, CD40LG, CCL2, FASLG and ABL1 had the highest priority. The identified priority genes can be considered as candidates for genotyping in the studies involving the search for associations with lymphedema.

CONCLUSIONS

Analysis of interactions of these genes in the associative gene network of lymphedema can improve understanding of mechanisms of interaction between endothelial apoptosis and lymphangiogenesis, and shed light on the role of disturbance of these processes in the development of edema, chronic inflammation and connective tissue transformation during the progression of the disease.

Promotive effects of bone morphogenetic protein 2 on angiogenesis in hepatocarcinoma via multiple signal pathways

The effects of Bone morphogenetic protein 2 (BMP-2) on the angiogenesis of hepatocellular carcinoma have not yet been observed and its molecular mechanisms is not clear. We first constructed the recombinant lentivirus vectors expressing small hairpin RNA against BMP-2 gene (LV-SH-BMP2) and the recombinant lentivirus vectors over-expressing BMP-2 (overexpression-LV-BMP2), and then the two recombinant lentivirus vectors were respectively transfected into Hep G2 cells. The Hep G2 cells transfected with LV-SH-BMP2 or overexpression-LV-BMP2 were respectively co-cultured with human umbilical vein endothelial cells (HUVECs) to observe the effects of BMP-2 on HUVECs. The effect of BMP-2 on tumor microvessel density (MVD) was examined. The abilities of proliferation, migration and angiogenesis were significantly inhibited in the HUVECs co-cultured with BMP-2 knockdown Hep G2 (all P < 0.05), but significantly enhanced in the HUVECs co-cultured with BMP-2 overexpression Hep G2 (all P < 0.05). MVD was significantly increased in overexpression-LV-BMP2-transfected Hep G2 tumor, but decreased in LV-SH-BMP2-transfected Hep G2 tumors. The protein expressions of VEGF, p-P38, p-ERK, p-AKT, p-m-TOR were significantly increased after BMP-2 over-expression, or significantly decreased after BMP-2 knockdown (all P < 0.05). These results reveal that BMP-2 can enhance HUVEC proliferation, migration and angiogenesis through P38, ERK and Akt/m-TOR pathway.

Effect of siRNA mediated bone morphogenetic protein 7 knockdown on cell proliferation and migration in human hepatoma cell line HepG2

AIM: To investigate the effect of small interfering RNA (siRNA) mediated bone morphogenetic protein 7 (BMP7) knockdown on the proliferation and migration of human hepatoma HepG2 cells.

METHODS: Three pairs of siRNAs targeting BMP7 were transiently transfected into HepG2 cells using TransLipid HL Transfection Reagent. HepG2 cells were divided into five groups including a normal control group, a negative-siRNA group and three transfected groups (transfected with BMP7-siRNA-1, BMP7-siRNA-2, and BMP7-siRNA-3, respectively). The expression of BMP7 mRNA and protein was measured by reverse transcript-polymerase chain reaction (RT-PCR) and Western blot, respectively, and the optimal siRNA sequence for BMP7 silencing was selected. The proliferation and migration of HepG2 cells after transfection were assessed by MTT assay and transwell migration assay, respectively. The expression of apoptosis-related proteins (Bax, Bcl-2, and Caspase3) in each group was determined by Western blot, and the cell cycle was analyzed by flow cytometry.

RESULTS: BMP7-siRNA-3 group demonstrated the lowest level of BMP7 expression among the five groups (P < 0.01). Cell growth was significantly slower in the BMP7-siRNA-3 group than in the control groups 48 h and 72 h after cells were transfected (P < 0.01). The numbers of cell passing the membrane were significantly lower in the BMP7-siRNA-3 group than in the control groups 24 h after cells were transfected (P < 0.01). The expression of Bax and Caspase3 (P < 0.01) was significantly increased after BMP7 silencing, and there was no statistically significant difference in the Bcl-2 expression. Flow cytometery showed that cells were significantly blocked in G₂ phase 48 h after cells were transfected with BMP7-siRNA-3 (P < 0.01).

CONCLUSION: SiRNA mediated BMP7 knockdown can inhibit HepG2 cell proliferation and migration, promote apoptosis and block cells in G₂ phase.