The molecular mechanism of LncRNA34a-mediated regulation of bone metastasis in hepatocellular carcinoma.

BACKGROUND: Bone metastasis (BM) has long been recognized as a major threat to the quality of life of hepatocellular cancer (HCC) patients. While LncRNA34a (Lnc34a) has been shown to regulate colon cancer stem cell asymmetric division, its effect on HCC BM remains unknown. METHODS: In situ hybridization and quantitative real-time polymerase chain reaction (qRT-PCR) were used to detect the expression of Lnc34a in HCC tissues and cell lines. Ventricle injection model was constructed to explore the effect of Lnc34a on BM in vivo. The methylation of miR-34a promoter and histones deacetylation were examined by using bisulfate-sequencing PCR and chromatin immunoprecipitation assays. RNA pull down and RNA immunoprecipitation were performed to investigated the interaction between Lnc34a and epigenetic regulators. Dual-luciferase reporter assay was conducted to find miR-34a target. The involvement of TGF-ß pathway in the BM from HCC was determined by qRT-PCR, western, and elisa assays. RESULTS: We found that Lnc34a was significantly overexpressed in HCC tissues and associated with BM. Both in vitro and in vivo experiments indicate that the restoration or knockdown of Lnc34a expression in HCC cells had a marked effect on cellular migration, invasion, and metastasis. Mechanistic analyses suggested that Lnc34a epigenetically suppresses miR-34a expression through recruiting DNMT3a via PHB2 to methylate miR-34a promoter and HDAC1 to promote histones deacetylation. On the other hand, miR-34a targets Smad4 via the TGF-ß pathway, followed by altering the transcription of the downstream genes (i.e., CTGF and IL-11) that are associated with BM. CONCLUSIONS: Our study is the first to document the pro-bone metastatic role of Lnc34a in BM of HCC and reveal a novel mechanism for the activation of the TGF-ß signaling pathway in HCC BM, providing evidence of a potential therapeutic strategy in HCC BM.

miR-146a-5p Alleviates Radiation-Induced Liver Fibrosis by Regulating PTPRA-SRC Signaling in Mice.

Patients with hepatobiliary tumors who accept radiotherapy are at risk for radiation-induced liver fibrosis. MicroRNAs (miRNAs) have been implicated in the pathogenesis of radiation-induced liver damage and possess potential as novel biomarkers and therapeutic targets. However, the role of miR-146a-5p in radiation-induced liver fibrosis is less well understood. The current study was designed to evaluate the role of miR-146a-5p in radiation-induced liver fibrosis in mice and to investigate the possible mechanisms involved in miR-146a-5p-mediated effects. The experiments were performed on Institute of Cancer Research (ICR) mice which received fractionated radiation (30 Gy in 5 fractions) to the liver. The results show radiation could induce histopathological changes, liver dysfunction and fibrosis accompanied with decreased miR-146a-5p expression. miR-146a-5p agomir treatment resulted in recovery of liver function and reduced the amount of alpha-smooth muscle actin (α-SMA), collagen 1, protein tyrosine phosphatase receptor type A (PTPRA) and phosphorylated SRC in the livers of irradiated mice. Therefore, our study reveals that miR-146a-5p inhibits the progression of hepatic fibrosis after radiation treatment. And the beneficial role of miR-146a-5p may be relevant to PTPRA-SRC signaling pathway.

Radiation Therapy Promotes Hepatocellular Carcinoma Immune Cloaking via PD-L1 Upregulation Induced by cGAS-STING Activation.

PURPOSE: Radiation therapy (RT) is one of the main treatments for patients with unresectable hepatocellular carcinoma (HCC). Emerging evidence indicates that the cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS) stimulator of interferon gene (STING) pathway is crucial in RT-induced antitumor immune responses. Here, we discovered that activation of the cancer cell-intrinsic cGAS-STING pathway mediated immune cloaking after RT-induced DNA damage. METHODS AND MATERIALS: Key regulatory proteins in the cGAS-STING signaling pathway in human and murine HCC cell lines were knocked out or down using CRISPR and CRISPR-associated protein 9 or small interfering RNA. The underlying mechanism of immune cloaking and clinical significance of cGAS-STING-induced programmed cell death ligand 1 (PD-L1) expression were studied with both ex vivo analyses and in vitro experiments. RESULTS: RT upregulated PD-L1 in patients with HCC, which correlated with poor survival. RT activated cGAS-STING, increasing immune-checkpoint PD-L1 expression in human and mouse liver cancer cells. Ionizing radiation activated the STING-TANK-binding kinase 1 (TBK1)-interferon regulatory factor 3 (IRF3) innate immune pathway, leading to PD-L1 upregulation in HCC cells and inhibiting cytotoxic T-lymphocyte activity and protecting tumor cells from immune-mediated eradication. Knockdown of cGAS, STING, TBK1, and IRF3 reversed the antitumor effect of cytotoxic T-lymphocyte-mediated cytotoxicity after ionizing radiation in vitro or in vivo. RT potentiated the antitumor effect of programmed cell death protein 1 and PD-L1 axis blockade and augmented cytotoxic T-cell (CTL) infiltration in HCC tumors in immunocompetent mice. CD8 depletion compromised the synergetic antitumor effect of combined RT and anti-PD-L1 blockade, demonstrating that CD8+ CTLs are required for antitumor immunity induced by combination therapy. CONCLUSIONS: Our results identified an immune-cloaking mechanism for RT-activated, innate immune cGAS-STING and suggested that RT enhances HCC immunotherapy.

Pre/Post-Treatment Dynamic of Inflammatory Markers Has Prognostic Value in Patients with Small Hepatocellular Carcinoma Managed by Stereotactic Body Radiation Therapy.

PURPOSE: The neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) are inflammatory indexes that may reflect immune response to tumors and prognosis. We investigated the prognostic values of pre-treatment and post-treatment NLR and PLR and changes in those ratios in patients with small hepatocellular carcinoma (sHCC) treated with stereotactic body radiation therapy (SBRT). PATIENTS AND METHODS: Sixty patients who received SBRT were retrospectively reviewed. NLR and PLR were calculated by division of neutrophil and platelet counts, respectively, by lymphocyte counts. Independent factors for progression-free survival (PFS) and overall survival (OS) were determined by the Kaplan-Meier method, log-rank test, and Cox multivariate regression. Hazard ratios (HRs) and 95% confidence intervals (CIs) were also calculated. RESULTS: The median follow-up was 36.9 (range: 4.1-73.5) months. Median PFS was 21.4 (range: 1.8-66.9) months. The 1-year and 2-year PFS rates were 76.7% and 55.0%, respectively. The 1-year and 2-year OS rates were 95.0% and 78.3%, respectively. In multivariate analysis, post-treatment PLR ≥263.0 indicated both poor PFS (HR: 3.70; 95% CI: 1.07-12.76, p=0.038) and OS (HR: 3.23; 95% CI: 1.01-9.11, p=0.043) for sHCC patients treated with SBRT. In addition, the presence of hepatitis infection and a low level of red blood cell count were also proved to be significantly associated with patients' poor prognosis (p<0.05 for each). Post-treatment increase in NLR ≥2.7-fold was shown to be a negative independent predictor of inferior OS (HR: 3.43; 95% CI: 1.14-10.38, p=0.029). CONCLUSION: High post-treatment PLR and change in NLR ≥2.7-fold were associated with poor prognosis in patients treated with SBRT and might be considered as reliable and independent prognostic biomarkers for patients with sHCC.

Association Between Circulating Lymphocyte Populations and Outcome After Stereotactic Body Radiation Therapy in Patients With Hepatocellular Carcinoma.

Background and Objective: Radiation-induced lymphopenia has a tangible impact on overall survival (OS) in multiple solid tumors. We investigated the association between circulating lymphocyte populations (CLPs) before and after stereotactic body radiation therapy (SBRT) and OS in patients with hepatocellular carcinoma (HCC). Materials and Methods: Seventy-eight HCC patients treated with SBRT between January 2013 and June 2017 were retrospectively analyzed. Baseline and post-treatment total peripheral lymphocyte counts (TPLCs) and values of different CLPs were obtained and analyzed for clinical outcomes. Univariate and multivariate Cox regression analyses were used to explore the independent prognostic factors for patient survival. Results: The one-, two- and three-year OS rates were 94.8, 75.9, and 63.3%, respectively. The mean TPLCs before and 10 days after SBRT were 1.4 × 109/L and 0.7 × 109/L, respectively. The TPLC recovered to its baseline value 1 year after SBRT. Multivariate analysis results revealed that variables, including tumor necrosis factor-alpha (TNF-α) level <5.5 ng/mL and post-treatment TPLC <0.45 × 109/L were independent factors for inferior OS. Further analysis showed that the values of CLPs, including CD3+, CD4+, CD8+, CD19+, and CD16+56+ cells dropped profoundly 10 days after SBRT, among which CD19+ B cell count was mostly depleted and gradually recovered after 2 months. Univariate analysis showed that both baseline and post-treatment TPLC and CLP (except post-treatment B cell) counts were significantly associated with patient OS (p < 0.05 for each). Further stratified analysis performed according to OS at 2 years demonstrated that the CD16+CD56+ NK cell counts remained significantly elevated in patients with better survival (OS > 2 years) compared to those in short-term survivors at 10 days, 1 month, and 2 months after SBRT (p < 0.05 for each). In addition, there were significant differences in TPLC and CD8+ T cell counts in patients with long-term and short-term OS at 2 months after SBRT (p < 0.05). Conclusions: Peripheral lymphopenia after SBRT might be an independent prognostic factor for poorer outcome in HCC patients. Post-treatment lymphocyte subsets, including CD8+ T cell and NK cell counts were also associated with 2-year OS rates.

MicroRNA-146a-5p Attenuates Fibrosis-related Molecules in Irradiated and TGF-beta1-Treated Human Hepatic Stellate Cells by Regulating PTPRA-SRC Signaling.

MicroRNAs (miRNAs) have been shown to play a pivotal role in the pathogenesis and maintenance of liver fibrosis by altering expression of their downstream target genes. However, their role in radiation-induced liver fibrosis has not been assessed in detail. Here, we investigated the role of miR-146a-5p and the target gene in regulation of fibrosis-related markers in the human hepatic stellate cell line LX2. LX2 cells were stimulated with 8 Gy of X rays and various concentrations of TGF-ß1 (0-5 ng/ml). Expression of α-SMA, collagen 1 and miR-146a-5p was evaluated. The MiR-146a-5p target gene predictions were performed using bioinformatics analysis and confirmed by dual-luciferase reporter experiment. The effect of miR-146a-5p and the involved target gene on the expression of these fibrogenic molecules was also assessed. Expression of α-SMA and collagen 1 were upregulated in response to radiation and/or TGF-ß1 treatment and miR-146a-5p levels were altered in LX2 cells. Restoration of miR-146a-5p expression suppressed expression of α-SMA and collagen 1 in irradiated and TGF-ß1-treated LX2 cells. Subsequent mechanism experiments revealed that miR-146a-5p overexpression inhibited PTPRA expression by binding to its 3'-untrans-lated region and reduced SRC activation. In addition, enhancement of PTPRA partially reversed the suppressive effect of miR-146a-5p on α-SMA and collagen 1 expression in LX2 cells. In conclusion, miR-146a-5p may negatively regulate the PTPRA-SRC signaling to inhibit expression of fibrosis-related markers in irradiated and TGF-ß1-stimulated LX2 cells.