Improvement of dendritic-based vaccine efficacy against hepatitis B virus–related hepatocellular carcinoma by two tumor-associated antigen gene–infected dendritic cells

Hepatoid adenocarcinoma-Clinicopathological features and molecular characteristics

Hepatoid adenocarcinoma (HAC) is a rare, malignant, extrahepatic tumor with histologic features similar to those of hepatocellular carcinoma. HAC is most often associated with elevated alpha-fetoprotein (AFP). HAC can occur in multiple organs, including the stomach, esophagus, colon, pancreas, lungs, and ovaries. HAC differs greatly from typical adenocarcinoma in terms of its biological aggression, poor prognosis, and clinicopathological characteristics. However, the mechanisms underlying its development and invasive metastasis remain unclear. The purpose of this review was to summarize the clinicopathological features, molecular traits, and molecular mechanisms driving the malignant phenotype of HAC, in order to support the clinical diagnosis and treatment of HAC.

Role of Alpha-Fetoprotein in Hepatocellular Carcinoma Drug Resistance

Hepatocellular carcinoma (HCC) is a major type of primary liver cancer and a major cause of cancer-related deaths worldwide because of its high recurrence rate and poor prognosis. Surgical resection is currently the major treatment measure for patients in the early and middle stages of the disease. Because due to late diagnosis, most patients already miss the opportunity for surgery upon disease confirmation, conservative chemotherapy (drug treatment) remains an important method of comprehensive treatment for patients with middle- and late-stage liver cancer. However, multidrug resistance (MDR) in patients with HCC severely reduces the treatment effect and is an important obstacle to chemotherapeutic success. Alpha-fetoprotein (AFP) is an important biomarker for the diagnosis of HCC. The serum expression levels of AFP in many patients with HCC are increased, and a persistently increased AFP level is a risk factor for HCC progression. Many studies have indicated that AFP functions as an immune suppressor, and AFP can promote malignant transformation during HCC development and might be involved in the process of MDR in patients with liver cancer. This review describes drug resistance mechanisms during HCC drug treatment and reviews the relationship between the mechanism of AFP in HCC development and progression and HCC drug resistance.

Caspase 3 may participate in the anti-tumor immunity of dendritic cells

BACKGROUND

Caspase 3 is not only involved in apoptosis, but also participates in the nonapoptotic functions. Previously, we found that caspase 3 gene knockout mice displayed decreased number of dendritic cells (DCs). However, whether caspase 3 participate in the function of DCs is unclear. Thus, the present study aims to investigate the role of caspase 3 in the maturation and antitumor function of DCs.

METHODS

Caspase 3 gene was overexpressed in DC2.4 cell line through Lentivirus system. The impact of caspase 3 gene overexpression on the biological behavior of DC2.4 cells was determined by CCK-8, colony formation and apoptosis analysis. The impact of caspase 3 gene overexpression on the antigen uptake, maturation, migration, T cell activation of DC2.4 cells was analyzed with phagocytosis, transwell and mixed lymphocyte reaction assay. Tumor growth and tumor infiltrated T cells were also investigated through tumor bearing model.

RESULTS

Caspase 3 gene overexpression could slightly increase the apoptosis of DC2.4 cells. Antigen uptake capability and maturation of DC2.4 cells were significantly promoted through caspases 3 gene overexpression. However, CXCR4 expression on DC2.4 cells and migration of DC2.4 cells were not influenced. Caspase 3 gene overexpression also enhanced the T cell activation and cytotoxicity of activated T cells. Finally, overexpression of caspase 3 gene significantly increased the tumor suppression of DC2.4 cells, accompanied by increased infiltration of CD4⁺ and CD8⁺ Cells in tumor tissue.

CONCLUSION

Caspase 3 gene overexpression could promote maturation and enhance antitumor capability of DC2.4 cells.

Alpha-Fetoprotein and Hepatocellular Carcinoma Immunity

Hepatocarcinoma is one of the most prevalent gastroenterological cancers in the world with less effective therapy. As an oncofetal antigen and diagnostic marker for liver cancer, alpha-fetoprotein (AFP) possesses a variety of biological functions. Except for its diagnosis in liver cancer, AFP has become a target for liver cancer immunotherapy. Although the immunogenicity of AFP is weak and it could induce the immune escapes through inhibiting the function of dendritic cells, natural killer cells, and T lymphocytes, AFP has attracted more attention in liver cancer immunotherapy. By in vitro modification, the immunogenicity and immune response of AFP could be enhanced. AFP-modified immune cell vaccine or peptide vaccine has displayed the specific antitumor immunity against AFP-positive tumor cells and laid a better foundation for the immunotherapy of liver cancer.

Pre-S2 Mutant-Induced Mammalian Target of Rapamycin Signal Pathways as Potential Therapeutic Targets for Hepatitis B Virus-Associated Hepatocellular Carcinoma

Chronic hepatitis B virus (HBV) infection is a major risk factor for hepatocellular carcinoma (HCC). Pre-S2 mutant represents an HBV oncoprotein that is accumulated in the endoplasmic reticulum (ER) and manifests as type II ground glass hepatocytes (GGHs). Pre-S2 mutant can induce ER stress and initiate multiple ER stress-dependent or -independent cellular signal pathways, leading to growth advantage of type II GGH. Importantly, the mammalian target of rapamycin (mTOR) signal pathways are consistently activated throughout the liver tumorigenesis in pre-S2 mutant transgenic mice and in human HCC tissues, leading to hepatocyte proliferation, metabolic disorders, and HCC tumorigenesis. In this review, we summarize the pre-S2 mutant-induced mTOR signal pathways and its implications in HBV-related HCC tumorigenesis. Clinically, the presence of pre-S2 mutant exhibits a high resistance to antiviral treatment and carries a high risk of HCC development in patients with chronic HBV infection. Targeting at pre-S2 mutant-induced mTOR signal pathways may thus provide potential strategies for the prevention or therapy of HBV-associated HCC.

Promising new strategies for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common causes of cancer death worldwide. It usually arises based on a background of chronic liver diseases, defined as the hypercarcinogenic state. The current treatment options for HCC ranging from locoregional treatments to chemotherapies, including sorafenib, effectively regulate the limited sizes and numbers of the nodules. However, these treatments remain unsatisfactory because they have insufficient antitumor effects on the large and numerous nodules associated with HCC and because of a high recurrence rate in the surrounding inflamed liver. To develop novel and promising therapies with higher antitumor effects, recent progress in identifying molecular targets and developing immunological procedures for HCC are reviewed. The molecular targets discussed include the intracellular signaling pathways of protein kinase B/mammalian target of rapamycin and RAS/RAF/mitogen-activated protein kinase, Wnt/β-catenin and glutamine synthetase, insulin-like growth factor, signal transducer and activator of transcription 3, nuclear factor-κB and telomerase reverse transcriptase, and c-MET. Immunological studies have focused mainly on target identification, T cells, natural killer cells, dendritic cells, natural killer T cells, and vaccine development.

The attenuated hepatocellular carcinoma-specific Listeria vaccine Lmdd-MPFG prevents tumor occurrence through immune regulation of dendritic cells

Immunotherapy is a promising treatment for liver cancer. Here, we tested the ability of the attenuated hepatocellular carcinoma-specific Listeria vaccine (Lmdd-MPFG) to treat hepatocellular carcinoma (HCC) in a mouse model. Immunization with the vaccine caused a strong anti-tumor response, especially in mice reinfused with dendritic cells (DCs). In mice that were also administered DCs, tumor suppression was accompanied by the strongest cytotoxic T lymphocyte response of all treatment groups and by induced differentiation of CD4+ T cells, especially Th17 cells. Additionally, the Lmdd-MPFG vaccine caused maturation of DCs in vitro. We demonstrated the synergistic effect of TLR4 and NLRP3 or NOD1 signaling pathways in LM-induced DC activation. These results suggest that the Lmdd-MPFG vaccine is a feasible strategy for preventing HCC.

Dendritic cells pulsed with Hsp70 and HBxAg induce specific antitumor immune responses in hepatitis B virus-associated hepatocellular carcinoma

Previous studies have drawn attention to dendritic cell (DC) vaccines; particularly the application of the tumor-associated antigen-targeted DC vaccine. The present study analyzed DCs derived from a normal individual and pulsed the cells with heat shock protein 70 peptide (Hsp70) and/or hepatitis B virus x antigen (HBxAg), a hepatocellular carcinoma (HCC)-associated antigen. It was then investigated whether this method of vaccination induced strong therapeutic antitumor immunity. The results revealed that the Hsp70/HBxAg complex-activated phenotype improves the functional maturation of DCs compared with using Hsp70 or HBxAg alone. Compared with either Hsp70 or HBxAg alone, matured DCs pulsed with the Hsp70/HBxAg complex stimulated a high level of autologous T-cell proliferation and induced HCC-specific cytotoxic T lymphocytes, which specifically killed HCC cells through a major histocompatibility complex class I mechanism. These results indicated that a vaccination therapy using DCs co-pulsed with the Hsp70/HBxAg complex is an effective strategy for immunotherapy and may offer a useful approach to protect against HCC.

Induction of protective and therapeutic anti-cancer immunity by using bispecific anti-idiotype antibody G22-I50 for nasopharyngeal carcinoma

Increasing evidence has suggested that bispecific and multivalent antibodies which have more antigen binding sites will improve their immunogenicity. The bispecific anti-idiotype antibody vaccine G22-I50 was obtained through genetic engineering to enhance the immunogenicity of anti-idiotype antibody vaccines G22 and I50. G22-I50 vaccination could induce anti-tumor immunity in the Balb/c mouse model. The protective and therapeutic efficacy of G22-I50 was also evaluated using the hu-PBL-SCID mouse model injected three times with G22-I50, G22, or I50 mixed with Freund's adjuvant. Results demonstrated that the protective anti-tumor effect of G22-I50 could be relevant with the production of Ab3 antibody and activation of CD8(+) cytotoxic T-lymphocytes. In preventive and therapeutic experiments, G22-I50 could reduce tumor size and prolong the survival time of HNE2-bearing mice (p<0.05). Human CD8(+) T lymphocytes infiltrated the tumor sites, and high levels of human IFN-γ, TNF-α, and caspase-3 were also detected in the tumors from G22-I50-vaccinated and -treated mice. Therefore, the bispecific anti-idiotype antibody vaccine G22-I50 can induce strong humoral and cell-mediated immune responses. This vaccine can be potentially applied to prevent and treat nasopharyngeal carcinoma.

Improvement of HBsAg gene-modified dendritic cell-based vaccine efficacy by optimizing immunization method or the application of β-glucosylceramide

Hepatocellular carcinoma (HCC) in China is mostly Hepatitis B virus infection related. The antitumor efficacy of HBsAg gene-modified dendritic cells (DC) has been widely tested both in vitro and in vivo. In this study, we analyzed whether adenoviral vector mediated HBsAg expression would alter cell surface phenotype or autologous T cell stimulating function of mature DCs. Further, the anti-tumor efficacy of pAd-HBsAg-DC-based vaccine was evaluated in mice bearing HBsAg expressing HCC. We also tested whether β-glucosylceramide (β-GC) would enhance the anti-tumor activity of pAd-HBsAg-DC. Results revealed that pAd-HBsAg-DC expressed and secreted HBsAg, while maintaining phenotypic characteristics of mature DCs. Vaccination with pAd-HBsAg-DC conferred specific therapeutic antitumor immunity to animal model bearing HBsAg expressing HCC. The application of β-GC activated mice hepatic NKT cells and enhanced the antitumor activity of pAd-HBsAg-DC. Most importantly, in vivo results showed that the inhibiting effect of pAd-HBsAg-DC vaccination on tumor growth was more significant when applied before tumor inoculation, suggesting that genetically modified DC based therapeutic cancer vaccine may achieve the most optimized antitumor effect when applied before tumor onset, and β-GC may serve as a potent innate immune enhancer for augmenting the antitumor effect of pAd-HBsAg-DC vaccine.

Gene carriers and transfection systems used in the recombination of dendritic cells for effective cancer immunotherapy

Dendritic cells (DCs) are the most potent antigen-presenting cells. They play a vital role in the initiation of immune response by presenting antigens to T cells and followed by induction of T-cell response. Reported research in animal studies indicated that vaccine immunity could be a promising alternative therapy for cancer patients. However, broad clinical utility has not been achieved yet, owing to the low transfection efficiency of DCs. Therefore, it is essential to improve the transfection efficiency of DC-based vaccination in immunotherapy. In several studies, DCs were genetically engineered by tumor-associated antigens or by immune molecules such as costimulatory molecules, cytokines, and chemokines. Encouraging results have been achieved in cancer treatment using various animal models. This paper describes the recent progress in gene delivery systems including viral vectors and nonviral carriers for DC-based genetically engineered vaccines. The reverse and three-dimensional transfection systems developed in DCs are also discussed.