acriflavine and Glioma

Glioblastomas have been historically difficult to treat with poor long-term survival. With novel strategies focused on targeting hypoxia-inducible factor (HIF) regulatory pathways, recent evidence has shown that Acriflavine (ACF) can effectively target glioma invasiveness and recurrence. However, local delivery of ACF and its combinatory effects with Temozolomide (TMZ) and radiation therapy (XRT) have not yet been optimized. In this study we test a novel polymeric matrix that can gradually release ACF at the tumor bed site in combination with systemic TMZ and XRT. In vitro cytotoxicity assays of ACF in combination with TMZ and XRT were performed on rodent and human cell lines with CCK-8 and flow cytometry. In vitro drug release was measured and intracranial safety was assessed in tumor-free animals. Finally, efficacy was assessed in an intracranial gliosarcoma model and combination therapy with TMZ and XRT evaluated. Combination therapy of ACF, TMZ, and XRT was able to reduce cell viability and induce apoptosis in glioma cells. In vitro and in vivo release of ACF was measured in benchtop and animal models. Efficacy was established in an in vivo gliosarcoma model in which intracranial ACF (p < 0.01) significantly improved median survival and the combination therapy of ACF, TMZ and XRT (p < 0.01) significantly improved median survival and led to long-term survival (LTS). We provide evidence that ACF, combined with TMZ and XRT, led to LTS in an intracranial model of rat gliosarcoma. These findings, in combination with the use of a novel polymeric matrix that allows more gradual drug delivery, constitute a first step in the translation of this novel strategy to human use.

Topics: Absorbable Implants; Acriflavine; Animals; Apoptosis; Brain Neoplasms; Cell Line, Tumor; Cell Survival; Combined Modality Therapy; Drug Implants; Glioma; Polymers; Radiotherapy Dosage; Rats; Rats, Inbred F344; Survival Rate; Temozolomide; Xenograft Model Antitumor Assays

Tumor progression, limited efficacy of current standard treatments, and the rise in patient mortality are associated with gene expression caused by the synergistic action of intratumoral hypoxia and HIF-1α activation. For this reason, recent investigations have focused on HIF-targeting therapeutic agents, with encouraging preclinical and clinical results in solid tumors. Here we describe the efficacy of a HIF-1α inhibitor, Acriflavine, and demonstrate its potency against brain cancer. This safe antibacterial dye induces cell death and apoptosis in several glioma cell lines, targets HIF-1α-mediated pathways, and decreases the level of PGK1, VEGF and HIF-1α in vitro and in vivo. Administered locally via biodegradable polymers, Acriflavine provides significant benefits in survival resulting in nearly 100% long term survival, confirmed by MRI and histological analyses. This study reports preclinical evidence that this safe, small molecule can contribute to brain tumor therapy and highlights the significance of HIF-1α-targeting molecules.

Topics: Acriflavine; Animals; Apoptosis; Brain; Brain Neoplasms; Cell Line, Tumor; Drug Delivery Systems; Fluorescent Dyes; Glioma; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; Rats, Inbred F344

Tumor-associated macrophages (TAMs) are enriched in gliomas and help create a tumor-immunosuppressive microenvironment. A distinct M2-skewed type of macrophages makes up the majority of glioma TAMs, and these cells exhibit pro-tumor functions. Gliomas contain large hypoxic areas, and the presence of a correlation between the density of M2-polarized TAMs and hypoxic areas suggests that hypoxia plays a supportive role during TAM recruitment and induction. Here, we investigated the effects of hypoxia on human macrophage recruitment and M2 polarization. We also investigated the influence of the HIF inhibitor acriflavine (ACF) on M2 TAM infiltration and tumor progression in vivo. We found that hypoxia increased periostin (POSTN) expression in glioma cells and promoted the recruitment of macrophages. Hypoxia-inducible POSTN expression was increased by TGF-α via the RTK/PI3K pathway, and this effect was blocked by treating hypoxic cells with ACF. We also demonstrated that both a hypoxic environment and hypoxia-treated glioma cell supernatants were capable of polarizing macrophages toward a M2 phenotype. ACF partially reversed the M2 polarization of macrophages by inhibiting the upregulation of M-CSFR in macrophages and TGF-β in glioma cells under hypoxic conditions. Administering ACF also ablated tumor progression in vivo. Our findings reveal a mechanism that underlies hypoxia-induced TAM enrichment and M2 polarization and suggest that pharmacologically inhibiting HIFs may reduce M2-polarized TAM infiltration and glioma progression.

Topics: Acriflavine; Animals; Antineoplastic Agents; Brain Neoplasms; Cell Adhesion Molecules; Cell Communication; Cell Plasticity; Cell Proliferation; Chemotaxis; Cytokines; ErbB Receptors; Glioma; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; Macrophages; Male; Mice, Inbred BALB C; Mice, Nude; Phosphatidylinositol 3-Kinase; Receptors, Granulocyte-Macrophage Colony-Stimulating Factor; RNA Interference; Signal Transduction; THP-1 Cells; Time Factors; Transfection; Transforming Growth Factor alpha; Transforming Growth Factor beta; Tumor Burden; Tumor Hypoxia; Tumor Microenvironment; Up-Regulation