A GM-CSF and CD40L bystander vaccine is effective in a murine breast cancer model

Suppression of the malignancy of mammary tumor in mice model by inactivated preparation of Mycobacterium obuense

Breast cancer (BC) is a significant cause of global mortality in women. This study was aimed to evaluate the immune-activation of malignant BC via the administration of attenuated Mycobacterium obuense. For this purpose, an in vivo model was developed with BALB/c mice. Mice were injected with 2.00 × 10⁶ 4T1 cells with breast tumor cell line. Forty-two mice were equally divided into control as well as low dose (0.20 mg 100 µL^-1) and high dose (0.50 mg 100 µL^-1) groups of M. obuense to investigate gene expression in the antitumor effects of M. obuense. In one group, paclitaxel was administrated as a choice drug in BC treatment. Antitumor manners were characterized by cytotoxicity against tumor target cells, size of the tumor and the expression of some BC metastatic genes together with pathology. The MTT assay demonstrated that different concentrations of both low and a high dose of bacteria did present no cytotoxicity effect on 4T1 cells. According to our findings, M. obuense significantly repressed tumor growth. M. obuense downregulated the expression of collagen type I alpha 1 (COLIA1), cFos, alkaline phosphatase (ALP), claudin 3 (cldn3), and conversely, activated transcription factor 4 (ATF4) and Twist related protein-1 (Twist1). All these alternations induced a decrease in the migratory and invasive capabilities of BC. The result of pathology was indicative of tumor regression in the paclitaxel and HK- M. obuense -recipient group. Thus, it seems most likely that M. obuense might impinge upon cell growth and metastatic behavior of malignant cells exerting anti-tumor activity in BC.

Cry1Ac Protoxin Confers Antitumor Adjuvant Effect in a Triple-Negative Breast Cancer Mouse Model by Improving Tumor Immunity

The Cry1Ac protoxin from Bacillus thuringiensis is a systemic and mucosal adjuvant, able to confer protective immunity in different infection murine models and induce both Th1 and TCD8+ cytotoxic lymphocyte responses, which are required to induce antitumor immunity. The Cry1Ac toxin, despite having not being characterized as an adjuvant, has also proved to be immunogenic and able to activate macrophages. Here, we investigated the potential antitumor adjuvant effect conferred by the Cry1Ac protoxin and Cry1Ac toxin in a triple negative breast cancer (TNBC) murine model. First, we evaluated the ability of Cry1Ac proteins to improve dendritic cell (DC) activation and cellular response through intraperitoneal (i.p.) coadministration with the 4T1 cellular lysate. Mice coadministered with the Cry1Ac protoxin showed an increase in the number and activation of CD11c+MHCII- and CD11c+MHCII+^low in the peritoneal cavity and an increase in DC activation (CD11c+MHCII+) in the spleen. Cry1Ac protoxin increased the proliferation of TCD4+ and TCD8+ lymphocytes in the spleen and mesenteric lymph nodes (MLN), while the Cry1Ac toxin only increased the proliferation of TCD4+ and TCD8+ in the MLN. Remarkably, when tested in the in vivo TNBC mouse model, prophylactic immunizations with 4T1 lysates plus the Cry1Ac protoxin protected mice from developing tumors. The antitumor effect conferred by the Cry1Ac protoxin also increased specific cytotoxic T cell responses, and prevented the typical tumor-related decrease of T cells (TCD3+ and TCD4+) as well the increase of myeloid-derived suppressor cells (MDSC) in spleen. Also in the tumor microenvironment of mice coadministered twice with Cry1Ac protoxin immunological improvements were found such as reductions in immunosupressive populations (T regulatory lymphocytes and MDSC) along with increases in macrophages upregulating CD86. These results show a differential antitumor adjuvant capability of Cry1Ac proteins, highlighting the ability of Cry1Ac protoxin to enhance local and systemic tumor immunity in TNBC. Finally, using a therapeutic approach, we evaluated the coadministration of Cry1Ac protoxin with doxorubicin. A significant reduction in tumor volume and lung metastasis was found, with increased intratumoral levels of tumor necrosis factor-α and IL-6 with respect to the vehicle group, further supporting its antitumor applicability.

The Role of the Tumor Microenvironment in Developing Successful Therapeutic and Secondary Prophylactic Breast Cancer Vaccines

Breast cancer affects roughly one in eight women over their lifetime and is a leading cause of cancer-related death in women. While outcomes have improved in recent years, prognosis remains poor for patients who present with either disseminated disease or aggressive molecular subtypes. Cancer immunotherapy has revolutionized the treatment of several cancers, with therapeutic vaccines aiming to direct the cytotoxic immune program against tumor cells showing particular promise. However, these results have yet to translate to breast cancer, which remains largely refractory from such approaches. Recent evidence suggests that the breast tumor microenvironment (TME) is an important and long understudied barrier to the efficacy of therapeutic vaccines. Through an improved understanding of the complex and biologically diverse breast TME, it may be possible to advance new combination strategies to render breast carcinomas sensitive to the effects of therapeutic vaccines. Here, we discuss past and present efforts to advance therapeutic vaccines in the treatment of breast cancer, the molecular mechanisms through which the TME contributes to the failure of such approaches, as well as the potential means through which these can be overcome.

Dendritic Cells in Anticancer Vaccination: Rationale for Ex Vivo Loading or In Vivo Targeting

Dendritic cells (DCs) have shown great potential as a component or target in the landscape of cancer immunotherapy. Different in vivo and ex vivo strategies of DC vaccine generation with different outcomes have been proposed. Numerous clinical trials have demonstrated their efficacy and safety in cancer patients. However, there is no consensus regarding which DC-based vaccine generation method is preferable. A problem of result comparison between trials in which different DC-loading or -targeting approaches have been applied remains. The employment of different DC generation and maturation methods, antigens and administration routes from trial to trial also limits the objective comparison of DC vaccines. In the present review, we discuss different methods of DC vaccine generation. We conclude that standardized trial designs, treatment settings and outcome assessment criteria will help to determine which DC vaccine generation approach should be applied in certain cancer cases. This will result in a reduction in alternatives in the selection of preferable DC-based vaccine tactics in patient. Moreover, it has become clear that the application of a DC vaccine alone is not sufficient and combination immunotherapy with recent advances, such as immune checkpoint inhibitors, should be employed to achieve a better clinical response and outcome.

CD40L-adjuvanted DNA vaccine carrying EBV-LMP2 antigen enhances anti-tumor effect in NPC transplantation tumor animal

CD40L, a costimulatory molecule for dendritic cells (DCs) and B cells, can serve as an adjuvant for enhancing the specific immune response induced by DNA vaccine carrying tumor-associated antigens. In this study, we investigated the potential of CD40L as an adjuvant to enhance the anti-tumor effect mediated by a DNA vaccine based on the Epstein-Barr virus-latent membrane protein 2 (EBV-LMP2) antigen. The plasmids capable of expressing the fusion protein EBV-LMP2-CD40L were constructed. Expression vector pVAX1 and plasmid expressing the individual antigen EBV-LMP2 were used as control groups. These plasmids were used to immunize female BALB/c mice (4-6 weeks old) at days 0, 7 and 14. The results suggest that immunization with DNA vaccines carrying fusion gene EBV-LMP2-CD40L can induce specific immunity more effectively than the plasmid expression individual antigen EBV-LMP2. In order to evaluate the anti-tumor effect of this DNA vaccine, we constructed a tumor bearing mouse model. After immunization, the tumor bearing mouse model, DNA vaccination with EBV-LMP2-CD40L plasmid significantly inhibited tumor growth in the tumor bearing mouse model and enhanced the tumor inhibition rate. This study demonstrated that encoding the EBV-LMP2 tumor antigen within an EBV-LMP2-CD40L DNA vaccine generates an effective antitumor response against EBV tumor, which may be a promising method to improve the antitumor immunity of DNA vaccine.

Long Noncoding RNA FOXC2-AS1 Predicts Poor Survival in Breast Cancer Patients and Promotes Cell Proliferation

Breast cancer (BC) is the most common malignant tumor in women. Recently, long noncoding RNAs (lncRNAs) have been proposed as critical regulators in biological processes, including tumorigenesis. FOXC2-AS1, a single antisense oligonucleotide RNA transcribed from the negative strand of forkhead box protein C2 (FOXC2), has been identified as an oncogene in osteosarcoma. In the present study, we investigated the prognosis value and biological role of FOXC2-AS1 in BC. Our findings revealed that FOXC2-AS1 was significantly increased in BC tissues and cell lines, and Kaplan–Meier survival analysis indicated that a high level of FOXC2-AS1 was associated with poor prognosis of BC patients. Loss of function revealed that silenced FOXC2-AS1 significantly suppressed the proliferation ability, and flow cytometric analysis illustrated the influence of FOXC2-AS1 on cell cycle and apoptosis rate. Finally, we found that cyclin D1, cyclin D2, and cyclin D3 were all partly positively modulated by FOXC2-AS1 in BC. Collectively, FOXC2-AS1 may serve as a promising prognostic biomarker and therapeutic target for BC patients.

Upregulation of lncRNA CASC2 Suppresses Cell Proliferation and Metastasis of Breast Cancer via Inactivation of the TGF-β Signaling Pathway

Breast cancer is one of the major malignancies with a mounting mortality rate in the world. Long noncoding RNA (lncRNA) cancer susceptibility candidate 2 (CASC2) has been identified to regulate the initiation and progression of multiple tumorous diseases according to previous studies. However, its biological role has been rarely reported in breast cancer. In the present study, lncRNA CASC2 was found to be significantly downregulated in breast cancer tissues and cell lines using real-time quantitative PCR. Furthermore, gain-of-function assays demonstrated that overexpression of lncRNA CASC2 significantly repressed breast cancer cell proliferation and metastasis. Moreover, CASC2 induced cell cycle arrest and much more early apoptosis of breast cancer. Additionally, based on the above research, we illustrated that inactivation of the TGF-β signaling pathway was involved in the function of lncRNA CASC2. Collectively, lncRNA CASC2 was a key factor in the tumorigenesis and malignancy of breast cancer, suggesting it may possibly be a potential therapy target for the treatment of breast cancer.