Cells isolated from residual intracranial tumors after treatment express iPSC genes and possess neural lineage differentiation plasticityResearch in context

Background: The goal of this study is to identify and characterize treatment resistant tumor initiating cells (TRTICs) using orthotopic xenografts. Methods: TRTICs were enriched from GBM cell lines using mouse xenografts treated with fractionated doses of radiation and temozolomide. TRTICs were characterized by neurosphere clonogenicity and self-renewal, serial xenotransplantation, differentiation potential, and mRNA & miRNA transcriptomic profiling. We use an unbiased approach to identify antigens encoding TRTIC and glioma stem cells (GSC) populations. Co-culture experiments of TRTIC and differentiated cells were conducted to evaluate the reliance of TRTIC differentiation on the secretome of differentiated cells. Findings: TRTICs acquire stem-like gene expression signatures and increased side population staining resulting from the activation of multi-drug resistance genes. Genetic and functional characterization of TRTICs shows a striking resemblance with GSCs. TRTICs can differentiate towards specific progeny in the neural stem cell lineage. TRTIC-derived tumors display all the histological hallmarks of glioblastoma (GBM) and exhibit a miRNA-transcript and mRNA-transcriptomic profile associated with aggressiveness. We report that CD24+/CD44+ antigens are expressed in TRTICs and patient-derived GSCs. Double positive CD24+/CD44+ exhibit treatment resistance and enhanced tumorigenicity. Interestingly, co-culture experiments with TRTICs and differentiated cells indicated that the regulation of TRTIC differentiation could rely on the secretome in the tumor niche. Interpretation: Radiation and temozolomide treatment enriches a population of cells that have increased iPSC gene expression. As few as 500 cells produced aggressive intracranial tumors resembling patient GBM. CD24+/CD44+ antigens are increased in TRTICs and patient-derived GSCs. The enrichment for TRTICs may result in part from the secretome of differentiated cells. Fund: NIH/NCI 1RC2CA148190, 1R01CA108633, 1R01CA188228, and The Ohio State University Comprehensive Cancer Center. Keywords: Treatment-resistance, Tumor-initiating, Glioma stem cell, CD24high/CD44high, Transcriptome, Neural lineag

Preparation, Biodistribution and Neurotoxicity of Liposomal Cisplatin following Convection Enhanced Delivery in Normal and F98 Glioma Bearing Rats

The purpose of this study was to evaluate two novel liposomal formulations of cisplatin as potential therapeutic agents for treatment of the F98 rat glioma. The first was a commercially produced agent, Lipoplatin TM, which currently is in a Phase III clinical trial for treatment of non-small cell lung cancer (NSCLC). The second, produced in our laboratory, was based on the ability of cisplatin to form coordination complexes with lipid cholesteryl hemisuccinate (CHEMS). The in vitro tumoricidal activity of the former previously has been described in detail by other investigators. The CHEMS liposomal formulation had a Pt loading efficiency of 25 % and showed more potent in vitro cytotoxicity against F98 glioma cells than free cisplatin at 24 h. In vivo CHEMS liposomes showed high retention at 24 h after intracerebral (i.c.) convection enhanced delivery (CED) to F98 glioma bearing rats. Neurotoxicologic studies were carried out in non-tumor bearing Fischer rats following i.c. CED of Lipoplatin TM or CHEMS liposomes or their ‘‘hollow’ ’ counterparts. Unexpectedly, Lipoplatin TM was highly neurotoxic when given i.c. by CED and resulted in death immediately following or within a few days after administration. Similarly ‘‘hollow’’ Lipoplatin TM liposomes showed similar neurotoxicity indicating that this was due to the liposomes themselves rather than the cisplatin. This was particularly surprising since Lipoplatin TM has been well tolerated when administered intravenously. In contrast, CHEMS liposomes and their ‘‘hollow’ ’ counterparts were clinically well tolerated. However, a variety of dos

The antitumor effects of IFN-α are abrogated in a STAT1-deficient mouse

IFN-α activates the signal transducer and activator of transcription (STAT) family of proteins; however, it is unknown whether IFN-α exerts its antitumor actions primarily through a direct effect on malignant cells or by stimulating the immune system. To investigate the contribution of STAT1 signaling within the tumor, we generated a STAT1-deficient melanoma cell line, AGS-1. We reconstituted STAT1 into AGS-1 cells by retroviral gene transfer. The resulting cell line (AGS-1(STAT1)) showed normal regulation of IFN-α–stimulated genes (e.g., H2k, ISG-54) as compared with AGS-1 cells infected with the empty vector (AGS-1(MSCV)). However, mice challenged with the AGS-1, AGS-1(STAT1), and AGS-1(MSCV) cell lines exhibited nearly identical survival in response to IFN-α treatment, indicating that restored STAT1 signaling within the tumor did not augment the antitumor activity of IFN-α. In contrast, STAT1(–/–) mice could not utilize exogenous IFN-α to inhibit the growth of STAT1(+/+) melanoma cells in either an intraperitoneal tumor model or in the adjuvant setting. The survival of tumor-bearing STAT1(–/–) mice was identical regardless of treatment (IFN-α or PBS). Additional cell depletion studies demonstrated that NK cells mediated the antitumor effects of IFN-α. Thus, STAT1-mediated gene regulation within immune effectors was necessary for mediating the antitumor effects of IFN-α in this experimental system

Clonogenic survival of F98 glioma cells following treatment with either free cisplatin or liposomal cisplatin for 4 or 24 h.

<p>Surviving fractions (S.Fs) were determined for the F98 glioma cells treated with (A) CHEMS lipsomes, (B) free cisplatin following a 4 h (•) or 24 h (○) exposure. Each data point represents the mean of 3 replicates ± the standard deviation.</p

Formulations of liposomal cisplatin preparations.

a<p>Hollow liposomes (before cisplatin loading).</p>b<p>Liposome/cisplatin measured immediately after preparation.</p>c<p>After lyophilization, 10 d storage at ambient temperature, and resuspension.</p>d<p>In water.</p>e<p>In 5% dextrose.</p

Comparison of the toxicity against F98 glioma cells of Lipoplatin™ and CHEMS cisplatin liposomes and their “hollow” counterparts.

a<p>F98 glioma cells were exposed to the test agent for 4 hours, following which clonogenic assays were carried.</p>b<p>Surviving fractions were determined following 7 days incubation at 37°C in a CO₂ incubator.</p>*<p>P-value is computed using two-sample t-test.</p