Downregulation of B7-H4 in the MHCC97-H hepatocellular carcinoma cell line by arsenic trioxide

Knockdown of liver cancer cell-secreted exosomal PSMA5 controls macrophage polarization to restrain cancer progression by blocking JAK2/STAT3 signaling

INTRODUCTION

Tumor-associated macrophages, a major component of the tumor microenvironment, undergo polarization into M2 macrophages (M2), and thereby exert an immunosuppressive effect to induce cancer metastasis. This study strives to uncover a molecular mechanism underlying this event in hepatocellular carcinoma (HCC).

METHODS

Proteasome subunit alpha 5 (PSMA5) expression in liver hepatocellular carcinoma (LIHC) tissues and its association with LIHC patients were predicted using StarBase. PSMA5 level in human HCC cells was manipulated via transfection. Exosomes were isolated from HCC cells, and internalized into macrophages which were cocultured with HCC cells. Exosome internalization was observed after fluorescence labeling. HCC cell migration and invasion were evaluated by wound healing and Transwell assays. Xenograft assay was performed to investigate the role of PSMA5 in in vitro tumorigenesis. M2 polarization was assessed by enzyme-linked immunosorbent assay, quantitative reverse transcription polymerase chain reaction, and immunohistochemistry. PSMA5 expression in exosomes and Janus Kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) activation in macrophages and tumors were detected by Western blot analysis.

RESULTS

High PSMA5 expression was observed in LIHC tissues and associated with compromised survival of LIHC patients. PSMA5 knockdown inhibited HCC cell migration and invasion. PSMA5 knockdown in HCC cells downregulated PSMA5 level in exosomes from these HCC cells. HCC cell-isolated exosomes were successfully internalized into macrophages, and facilitated M2 polarization and JAK2/STAT3 pathway activation. HCC cell-secreted exosomal PSMA5 knockdown inhibited the exosome-induced effect on macrophages, and attenuated the promotion induced by exosome-treated macrophages on HCC cell migration/invasion and tumorigenesis along with in vivo M2 polarization and JAK2/STAT3 pathway activation.

CONCLUSION

HCC cell-secreted exosomal PSMA5 knockdown hinders M2 polarization to suppress cancer progression by restraining JAK2/STAT3 signaling.

Nanocarrier-based delivery of arsenic trioxide for hepatocellular carcinoma therapy

Hepatocellular carcinoma (HCC) poses a severe threat to human health and economic development. Despite many attempts at HCC treatment, most are inevitably affected by the genetic instability and variability of tumor cells. Arsenic trioxide (ATO) has shown to be effective in HCC. However, time-consuming challenges, especially the optimal concentration in tumor tissue and bioavailability of ATO, remain to be overcome for its transition from the bench to the bedside. To bypass these issues, nanotechnology-based delivery systems have been developed for prevention, diagnosis, monitoring and treatment in recent years. This article is a systematic overview of the latest contributions and detailed insights into ATO-loaded nanocarriers, with particular attention paid to strategies for improving the efficacy of nanocarriers of ATO.

Current status and future directions of hepatocellular carcinoma-targeted nanoparticles and nanomedicine

INTRODUCTION

Hepatocellular carcinoma (HCC) is a major health problem worldwide. Conventional therapies covering either chemotherapy or combination therapy still have sub-optimal responses with significant adverse effects and toxicity. Moreover, tumor cells usually acquire resistance quickly for traditional approaches, limiting their use in HCC. Interest in nanomedicine due to minimal systemic toxicity and a high degree of target-specific drug-delivery have pulled the attention of health scientists in this area of therapeutics.

AREA COVERED

The review covers the incidence and epidemiology of HCC, proposed molecular drug targets, mechanistic approach and emergence of nanomedicines including nanoparticles, lipidic nanoparticles, vesicular-based nanocarrier, virus-like particles with momentous therapeutic aspects including biocompatibility, and toxicity of nanocarriers along with conclusions and future perspective, with an efficient approach to safely cross physiological barriers to reach the target site for treating liver cancer.

EXPERT OPINION

Remarkable outcomes have recently been observed for the therapeutic efficacy of nanocarriers with respect to a specific drug target against the treatment of HCC by existing under trial drugs.

Arsenic trioxide-loaded CalliSpheres: In vitro study of drug release and antitumor activity, and in vivo study of pharmacokinetics, treatment efficacy and safety in liver cancer

The aim of the present study was to investigate the arsenic trioxide (ATO) loading/releasing efficiency of CalliSphere beads (CBs), as well as the in vitro anticancer activity, in vivo pharmacokinetics, treatment efficacy and safety of ATO-eluting CBs in liver cancer. The ATO loading and releasing efficiencies in CBs were evaluated. Furthermore, cell viability, invasion, apoptosis, VEGF expression and MMP9 expression were determined in liver cancer cells treated with ATO-eluting CBs or ATO solution. Rabbit liver models were established and underwent TACE with ATO-eluting CBs or ATO/lipiodol emulsion. Subsequently, their ATO pharmacokinetics were determined and macroscopic/microscopic examinations were conducted. In vitro, CB-loaded ATO increased during 40 min with an optimal loading efficiency of 23.0±2.5%, and released ATO rapidly within the first 30 min (31.40±10.0%) then slowed down within the latter 48 h (47.20±4.70%). ATO-eluting CBs exhibited decreased cell viability to some extent and similar invasive cell count, apoptosis rate, VEGF and MMP9 levels compared with ATO solution at various concentrations and time-points. In vivo, ATO concentration was lower in plasma, but higher in tumor tissues, and necrosis was more complete in tumor tissue while milder in normal liver parenchyma after rabbit liver was embolized with ATO-eluting CBs compared with ATO/lipiodol emulsion. ATO-eluting CBs may be a novel and promising therapeutic option in treating liver cancer.

Novel Mechanistic Insights into the Anti-cancer Mode of Arsenic Trioxide

Arsenic, a naturally-occurring toxic element, and a traditionally-used drug, has received a great deal of attention worldwide due to its curative anti-cancer properties in patients with acute promyelocytic leukemia. Among the arsenicals, arsenic trioxide has been most widely used as an anti-cancer drug. Recent advances in cancer therapeutics have led to a paradigm shift away from traditional cytotoxic drugs towards the targeting of proteins closely associated with driving the cancer phenotype. Due to the diverse anti-cancer effects of ATO on different types of malignancies, numerous studies have made efforts to uncover the mechanisms of ATO-induced tumor suppression. From in vitro cellular models to studies in clinical settings, ATO has been extensively studied. The outcomes of these studies have opened doors to establishing improved molecular-targeted therapies for cancer treatment. The efficacy of ATO has been augmented by combination with other drugs. In this review, we discuss recent arsenic-based cancer therapies and summarize the novel underlying molecular mechanisms of the anti-cancer effects of ATO.

Antitumor properties of arsenic trioxide-loaded CalliSpheres® microspheres by transarterial chemoembolization in VX2 liver tumor rabbits: suppression of tumor growth, angiogenesis, and metastasis and elongation of survival

This study aimed to investigate the antitumor effect of arsenic trioxide (ATO)-loaded CalliSpheres^® microspheres (CSM) by transarterial chemoembolization (TACE) in rabbits with VX2 liver tumors. A total of 120 VX2 liver tumor rabbits were randomized into four groups (N = 30 for each group), which received ATO-loaded CSM by TACE (CSM-ATO group), ATO by conventional TACE (cTACE-ATO group), transcatheter arterial embolization using CSM (TAE-CSM group), and saline arterial injection (control group). Five rabbits in each group were sacrificed at 12 h, 3 d, 7 d and 14 d, and then tumor proliferation, apoptosis, and angiogenesis/epithelial-mesenchymal transition (EMT) markers were detected. Tumor volume, metastasis status and ascites were assessed at 14 d. Ten rabbits in each group were observed until death for accumulating survival calculation. Tumor volume and ascites were decreased in the CSM-ATO group compared to the cTACE-ATO and TAE-CSM groups. Pulmonary, abdominal wall and omentum metastases were reduced while accumulating survival was increased in the CSM-ATO group compared to the TAE-CSM group. However, no difference in metastasis foci or survival between the CSM-ATO and cTACE-ATO groups was discovered. Meanwhile, tumor apoptosis was promoted while proliferation was suppressed in the CSM-ATO group compared to the cTACE-ATO and TAE-CSM groups. Additionally, HIF-1α, VEGF and microvessel density were decreased in the CSM-ATO group compared to the cTACE-ATO and TAE-CSM groups. Additionally, twist, N-cadherin, vimentin and MMP-9 were reduced while E-cadherin was enhanced in the CSM-ATO group compared to the cTACE-ATO and TAE-CSM groups. In conclusion, ATO-loaded CSM by TACE suppressed tumor growth, angiogenesis, and metastasis and elongated survival in VX2 liver tumor rabbits.

B7-H4, a promising target for immunotherapy

The coinhibitory molecule B7-H4, an important member of the B7 family, is abnormally expressed in tumors, inflammation and autoimmune diseases. B7-H4 negatively regulates T cell immune response and promotes immune escape by inhibiting the proliferation, cytokine secretion, and cell cycle of T cells. Moreover, B7-H4 plays an extremely important role in tumorigenesis and tumor development including cell proliferation, invasion, metastasis, anti-apoptosis, etc. In addition, B7-H4 has the other biological functions, such as protection against type 1 diabetes (T1D) and islet cell transplantation. Therefore, B7-H4 has been identified as a novel marker or a therapeutic target for the treatment of tumors, inflammation, autoimmune diseases, and organ transplantation. Here, we summarized the expression profiles, physiological and pathological functions, and regulatory mechanisms of B7-H4, the signaling pathways involved, as well as B7-H4-based immunotherapy.

B7-Homolog 4 Promotes Epithelial-Mesenchymal Transition and Invasion of Bladder Cancer Cells via Activation of Nuclear Factor-κB

B7-homolog 4 (B7-H4), a member of the B7 family of costimulatory molecules, has been reported to be upregulated in urothelial cell carcinoma. This study was conducted to explore the biological role of B7-H4 in the aggressiveness of bladder cancer and the associated molecular mechanism. We found that the mRNA and protein levels of B7-H4 were significantly greater in bladder cancer cell lines than in SV-HUC-1 (normal human urothelial cells). Overexpression of B7-H4 significantly promoted bladder cancer cell migration and invasion, whereas knockdown of B7-H4 exerted an opposite effect. However, the growth of bladder cancer cells was not altered by B7-H4 overexpression or knockdown. Overexpression of B7-H4 promoted epithelial–mesenchymal transition (EMT), as evidenced by decreased E-cadherin and increased vimentin expression. The EMT inducers Twist1 and Snail were upregulated by B7-H4 overexpression and downregulated by B7-H4 silencing. Mechanistically, overexpression of B7-H4 induced the activation of NF-κB signaling. Pharmacological inhibition of NF-κB partially prevented B7-H4-mediated bladder cancer cell invasion. Taken together, B7-H4/NF-κB signaling is involved in the EMT and invasion of bladder cancer cells and represents a new candidate target for the treatment of bladder cancer.

Therapeutic Potential of Arsenic Trioxide (ATO) in Treatment of Hepatocellular Carcinoma: Role of Oxidative Stress in ATO-Induced Apoptosis

Hepatocellular carcinoma (HCC), the dominant form of primary liver cancer, is the sixth most common cancer in the world with more than 700,000 people diagnosed annually. Arsenic trioxide (ATO) has been shown to be a potent anticancer agent in various carcinomas, proving particularly effective in the clinical treatment of relapsed and refractory acute promyelocytic leukemia. However, its bioactivity and molecular mechanisms against HCC has not been fully studied. Using human HCC (HepG2) cells as a test model, we studied the effects of ATO and examined the role of oxidative stress (OS) and apoptosis in cytotoxicity. OS biomarkers showed a significant increase (p< 0.05) of malondialdehyde concentrations, and a gradual decrease of antioxidant enzymes (GPx & CAT) activities with increasing ATO doses. Flow cytometry data showed a dose dependent increase in annex in V positive cells and caspase 3 activities. These results were confirmed by data of the DNA laddering assay showing a clear evidence of nucleosomal DNA fragmentation, as well as data from Western blotting showing a significant modulation of specific apoptotic related proteins, including the activation of p53 and p21 expression and the down-regulation of Bcl-2 expression in ATO-treated cells. Taken together, our research demonstrates that ATO has a potential therapeutic effect against HCC, and its cytotoxicity may be mediated via oxidative stress and activation of the mitochondrial or intrinsic pathway of apoptosis.