Immunizations With IFNγ Secreting Tumor Cells can Eliminate Fully Established and Invasive Rat Gliomas

Intratumorally implanted mesenchymal stromal cells potentiate peripheral immunotherapy against malignant rat gliomas

Bone marrow-derived mesenchymal stromal cells (MSCs) target glioma extensions and micro-satellites efficiently when implanted intratumorally. Here, we report that intratumoral implantation of MSCs and peripheral immunotherapy with interferon-gamma (IFNγ) producing tumor cells improve the survival of glioma-bearing rats (54% cure rate) compared to MSC alone (0% cure rate) or immunotherapy alone (21% cure rate) by enforcing an intratumoral CD8(+) T cell response. Further analysis revealed that the MSCs up-regulate MHC classes I and II in response to IFNγ treatment in vitro and secrete low amounts of immunosuppressive molecules prostaglandin E2 and interleukin-10.

IFNγ in combination with IL-7 enhances immunotherapy in two rat glioma models

Peripheral immunization, using a combination of interferon-gamma (IFNγ)- and interleukin-7 (IL-7)-producing tumor cells, eradicated 75% of pre-established intracerebral N32 rat glioma tumors, and prolonged survival in the more aggressive RG2 model. Rats immunized with IFNγ- and IL7-transduced N32 cells displayed increases in IFNγ plasma levels and proliferating circulating T cells when compared with rats immunized with N32-wild type cells. Following irradiation, the expression of MHC I and II was high on N32-IFNγ cells, but low on RG2-IFNγ cells. In conclusion, IFNγ and IL-7 immunizations prolong survival in two rat glioma models.

Inhibition of cyclooxygenase-2 enhances immunotherapy against experimental brain tumors

Glioblastoma multiforme is the most common and aggressive malignant brain tumor in humans, and the prognosis is very poor despite conventional therapy. Immunotherapy represents a novel treatment approach, but the effect is often weakened by release of immune-suppressive molecules such as prostaglandins. In the current study, we investigated the effect of immunotherapy with irradiated interferon-γ (IFN-γ)-secreting tumor cells and administration of the selective cyclooxygenase-2 (COX-2) inhibitor parecoxib as treatment of established rat brain tumors. COX-2 inhibition and immunotherapy significantly enhanced the long-term cure rate (81% survival) compared with immunotherapy alone (19% survival), and there was a significant increase in plasma IFN-γ levels in animals treated with the combined therapy, suggesting a systemic T helper 1 immune response. COX-2 inhibition alone, however, did neither induce cure nor prolonged survival. The tumor cells were identified as the major source of COX-2 both in vivo and in vitro, and unmodified tumor cells produced prostaglandin E(2) in vitro, while the IFN-γ expressing tumor cells secreted significantly lower levels. In conclusion, we show that immunotherapy of experimental brain tumors is greatly potentiated when combined with COX-2 inhibition. Based on our results, the clinically available drug parecoxib may be added to immunotherapy against human brain tumors. Furthermore, the discovery that IFN-γ plasma levels can be used to determine the ongoing in vivo immune response has translational potential.

Chemotherapeutic candidate inducing immunological death of human tumor cell lines

The immunological death induction by EY-6 on the human tumor cell lines was screened. Human colon carcinoma (HCT15, HCT116), gastric carcinoma (MKN74, SNU668), and myeloma (KMS20, KMS26, KMS34) cells were died by EY-6 treatment with dose-dependent manner. CRT expression, a typical marker for the immunological death, was increased on the EY-6-treated colorectal and gastric cancer cells. Interestingly, the effects on the myeloma cell lines were complicated showing cell line dependent differential modulation. Cytokine secretion from the EY-6 treated tumor cells were dose and cell-dependent. IFN-γ and IL-12 secretion was increased in the treated cells (200% to over 1000% of non-treated control), except HCT116, SNU668 and KMS26 cells which their secretion was declined by EY-6. Data suggest the potential of EY-6 as a new type of immuno-chemotherapeutics inducing tumor-specific cell death. Further studies are planned to confirm the efficacy of EY-6 including in vivo study.

Cellular Mechanism of Newly Synthesized Indoledione Derivative-induced Immunological Death of Tumor Cell

BACKGROUND

EY-6 is one of the newly synthesized indoledione derivatives to induce tumor cell-specific cell death. In this study, we investigated the mechanism of immunological death induced by EY-6 at mouse colon cancer cell as well as at the normal immune cell represented by dendritic cell.

METHODS

C57BL/6 mouse syngeneic colon cancer cell MC38 was treated with EY-6, and analyzed by MTT for viability test, flow cytometry for confirming surface expressing molecules and ELISA for detection of cytokine secretion. Normal myeloid-dendritic cell (DC) was ex vivo cultured from bone marrow hematopoietic stem cells of C57BL/6 mice with GM-CSF and IL-4 to analyze the DC uptake of dead tumor cells and to observe the effect of EY-6 on the normal DC.

RESULTS

EY-6 killed the MC38 tumor cells in a dose dependent manner (25, 50 and 100 µM) with carleticulin induction. And EY-6 induced the secretion of IFN-γ but not of TNF-α from the MC38 tumor cells. EY-6 did not kill the ex-vivo cultured DCs at the dose killing tumor cells and did slightly but not significantly induced the DC maturation. The OVA-specific cross-presentation ability of DC was not induced by chemical treatment (both MHC II and MHC I-restricted antigen presentation).

CONCLUSION

Data indicate that the EY-6 induced tumor cell specific and immunological cell death by modulation of tumor cell phenotype and cytokine secretion favoring induction of specific immunity eliminating tumor cells.

Understanding the role of cytokines in Glioblastoma Multiforme pathogenesis

Cytokines play a significant role in cancer diagnosis, prognosis and therapy. The immune system's failure to recognize the malignant tumor cells and mount an effective response may be the result of tumor-associated cytokine deregulation. Glioblastoma Multiforme (GBM) has a characteristic cytokine expression pattern, and abnormalities in cytokine expression have been implicated in gliomagenesis. Within the heterogeneous GBM microenvironment, the tumor cells, normal brain cells, immune cells, and stem cells interact with each other through the complex cytokine network. This review summarizes the current understanding of the functions of key cytokines on GBM, and highlights potential therapeutic applications targeting these cytokines.

IL-10 and TGF-β2 are overexpressed in tumor spheres cultured from human gliomas

Immune-associated cytokines including IL-10 and TGF-β2 are thought to play a crucial role in immunosuppression mediated by gliomas. We have investigated the possibility that glioma stem cells are the major source of these cytokines. Tumor spheres, clonal non-adherent cell colonies derived from a single tumor stem cell, were cultured from surgical specimens of eight glioma patients, including two glioblastoma multiformes (grade IV), one anaplastic oligodendroglioma (grade III) and five anaplastic astrocytomas (grade III). Real-time RT-PCR and immunoassay were used to compare the relative expression levels of IL-10 and TGF-β2 in stem-cell-derived tumor sphere cells (TSCs) and primary cultured glioma cells (PCGCs). TSCs were confirmed to express the brain tumor stem cell marker CD133, and on in vitro differentiation gave rise to cells expressing neuronal or glial markers. RT-PCR and immunoassay revealed that mRNA and protein levels of both IL-10 and TGF-β2 were significantly higher in TSCs than in PCGCs from the same tumor. Interestingly, the degree of overexpression in TSCs, but not in PCGS, appeared to correlate with the pathological grade of the glioma. These findings suggest that glioma stem cells are likely to be the major tumor source of immunosuppressive cytokines and thereby play a crucial role in determining glioma malignancy.

Intratumoral IL-7 delivery by mesenchymal stromal cells potentiates IFNgamma-transduced tumor cell immunotherapy of experimental glioma

The present study reports regression of pre-established experimental rat gliomas as a result of combining peripheral immunization using interferon gamma (IFNgamma) transduced autologous tumor cells with local intratumoral delivery of interleukin 7 (IL-7) by mesenchymal stromal cells. IL-7 alone significantly decreased the tumor area and this effect was enhanced with IFNgamma immunization. A higher density of intratumoral T-cells was observed in animals receiving combined therapies compared to rats receiving either cytokine alone suggesting that the therapeutic effect is dependent on a T-cell response.