Histone deacetylase inhibitors prevent activation-induced cell death and promote anti-tumor immunity

The poor efficacy of the in vivo anti-tumor immune response has been partially attributed to ineffective T-cell responses mounted against the tumor. Fas-FasL-dependent activation-induced cell death (AICD) of T cells is believed to be a major contributor to compromised anti-tumor immunity. The molecular mechanisms of AICD are well-investigated, yet the possibility of regulating AICD for cancer therapy remains to be explored. In this study, we show that histone deacetylase inhibitors (HDACIs) can inhibit apoptosis of CD4⁺ T cells within the tumor, thereby enhancing anti-tumor immune responses and suppressing melanoma growth. This inhibitory effect is specific for AICD through suppressing NFAT1-regulated FasL expression on activated CD4⁺ T cells. In gld/gld mice with mutation in FasL, the beneficial effect of HDACIs on AICD of infiltrating CD4⁺ T cells is not seen, confirming the critical role of FasL regulation in the anti-tumor effect of HDACIs. Importantly, we found that the co-administration of HDACIs and anti-CTLA4 could further enhance the infiltration of CD4⁺ T cells and achieve a synergistic therapeutic effect on tumor. Therefore, our study demonstrates that the modulation of AICD of tumor-infiltrating CD4⁺ T cells using HDACIs can enhance anti-tumor immune responses, uncovering a novel mechanism underlying the anti-tumor effect of HDACIs.

Are changes in HLA Ags responsible for leukemia relapse after HLA-matched allogeneic hematopoietic SCT?

Loss of heterozygosity (LOH) has been shown to be associated with leukemia relapse after haploidentical transplantation. Whether such changes are an important cause of relapse after HLA-matched transplantation remains unclear. We retrospectively HLA-typed leukemic blasts for 71 patients with AML/myelodysplastic syndrome obtained from stored samples, and the results were compared with those obtained at diagnosis and/or before the transplant. No LOH or any other changes in HLA Ag were found in any of the samples tested post transplant as compared with pretransplant specimens. One patient had LOH in HLA class I Ag (HLA-A,-B and -C); however, these changes were present in the pretransplant sample indicating that they occurred before the transplant. We concluded that, in contrast with haploidentical transplantation, HLA loss does not have a major role as a mechanism of relapse after allogeneic transplantation with a closely HLA-matched donor.

Metal-carbonyl organometallic polymers, PFpP, as resists for high-resolution positive and negative electron beam lithography

Metal-carbonyl organometallic polymers, PFpP, can function as high-resolution resists for electron beam lithography.

Phase II randomized study of whole-brain radiation therapy with or without concurrent temozolomide for brain metastases from breast cancer

BACKGROUND

To improve the therapeutic index of whole-brain radiation therapy (WBRT) in the treatment of brain metastases (BM) from breast cancer, we investigated the efficacy and safety of WBRT combined with temozolomide (TMZ) in this population.

PATIENTS AND METHODS

This phase II multicenter prospective randomized study included patients with newly diagnosed intraparenchymal BMs from breast cancer, unsuitable for surgery or radiosurgery. All patients received conformal WBRT (3 Gy × 10-30 Gy), with or without concomitant TMZ administered at a dosage of 75 mg/m(2)/day during the irradiation period. The primary end point was objective response rate (ORR) 6 weeks after the end of treatment, defined as a partial or complete response on systematic brain MRI (modified WHO criteria). Secondary end points were progression-free survival (PFS) and overall survival (OS), neurologic symptoms, and tolerability.

RESULTS

Between February 2008 and November 2010, 100 patients were enrolled in the study (50 in the WBRT + TMZ arm, 50 in the WBRT arm). Median age was 55 years (29-79). Median follow-up was 9.4 months [1.0-68.1]. ORRs at 6 weeks were 36% in the WBRT arm and 30% in the WBRT + TMZ arm (NS). In the WBRT arm, median PFS was 7.4 months and median OS was 11.1 months. In the WBRT + TMZ arm, median PFS was 6.9 months and median OS was 9.4 months. Treatment was well tolerated in this arm: the most common ≥grade 2 acute toxicity was reversible lymphopenia.

CONCLUSION

WBRT combined with TMZ did not significantly improve local control and survival in patients with BMs from breast cancer. CLINICALTRIALS.GOV: NCT00875355.

Zeaxanthin induces Nrf2-mediated phase II enzymes in protection of cell death

Zeaxanthin (Zea) is a major carotenoid pigment contained in human retina, and its daily supplementation associated with lower risk of age-related macular degeneration. Despite known property of Zea as an antioxidant, its underlying molecular mechanisms of action remain poorly understood. In this study, we aim to study the regulation mechanism of Zea on phase II detoxification enzymes. In normal human retinal pigment epithelium cells, Zea promoted the nuclear translocation of NF-E2-related factor 2 (Nrf2) and induced mRNA and protein expression of phase II enzymes, the induction was suppressed by specific knockdown of Nrf2. Zea also effectively protected against tert-butyl hydroperoxide-induced mitochondrial dysfunction and apoptosis. Glutathione (GSH) as the most important antioxidant was also induced by Zea through Nrf2 activation in a time- and dose-dependent manner, whereas the protective effects of Zea were decimated by inhibition of GSH synthesis. Finally, Zea activated the PI3K/Akt and MAPK/ERK pathway, whereas only PI3K/Akt activation correlated with phase II enzymes induction and Zea protection. In further in vivo analyses, Zea showed effects of inducing phase II enzymes and increased GSH content, which contributed to the reduced lipid and protein peroxidation in the retina as well as the liver, heart, and serum of the Sprague–Dawley rats. For the first time, Zea is presented as a phase II enzymes inducer instead of being an antioxidant. By activating Nrf2-mediated phase II enzymes, Zea could enhance anti-oxidative capacity and prevent cell death both in vivo and in vitro.

Multiplex RT-PCR detection and distribution of four apple viruses in China

Apple trees are natural hosts of four economically important virus species in China. We used a simple, sensitive multiplex RT-PCR protocol with an internal control to simultaneously detect and differentiate four apple viruses: apple chlorotic leaf spot virus (ACLSV), apple mosaic virus (ApMV), apple stem pitting virus (ASPV), and apple stem grooving virus (ASGV). This multiplex RT-PCR could be used as an alternative to other routinely used detection methods. We used this protocol to evaluate the occurrence and distribution of the four apple viruses in China. The four viruses were widely distributed throughout the main apple production region of China, including Heilongjiang, Liaoning, Hebei, Beijing, Henan, Shanxi, Shaanxi, Shandong, Gansu, Ningxia, Xinjiang, Sichuan, and Yunnan. The four viruses, ApMV, ASPV, ASGV, and ACLSV, were present in 80.1%, 65.1%, 73.7%, and 69.7% of the samples, respectively. Two or more of the viruses were detected in most of the infections. The most frequent virus combinations were ApMV + ASGV + ASPV + ACLSV with an incidence of 27.22%, followed by ApMV + ASGV + ACLSV (14.37%), ApMV + ASGV + ASPV (12.54%), and ASGV + ApMV (11.01%). The incidence of the ASPV + ACLSV combination was the lowest (0.61%). This is the first extensive survey conducted in China for monitoring the four apple viruses, which provides important information for apple virus distribution and management in China.

Abstract P6-11-01: A randomized phase II clinical trial of whole-brain radiation therapy plus concomitant temozolomide in treatment of brain metastases from breast cancer: Six-month follow-up results

Background: Despite of therapeutics progress in advanced breast cancer, brain metastases occurrence remain a frequent and delicate situation. The efficacy of whole-brain radiation therapy (WBRT), still considered as the standard local treatment in case of multiple brain metastases, is limited. Recently, several phase II studies have shown some efficacy of the association of WBRT and temozolomide (TMZ), an oral alkylating agent already known as a radiosensitizer, with improved brain control rate (44 to 96%). Patients with breast cancer were underrepresented and none of these trials have studied this combined treatment issue in this specific population. The aim of this study was to assess the efficacy and safety of WBRT combined with temozolomide in the treatment of brain metastases from breast cancer.

Materials and Methods: A prospective randomized multicenter phase II study was developed, using a modified two-stage Fleming design. Patients with newly diagnosed intraparenchymal brain metastases from breast cancer, not suitable for surgery nor radiosurgery, were included. All patients received conformational WBRT (3 Gy x 10 to 30 Gy). They were randomized to WBRT plus concomitant TMZ administered 75 mg/m2/day during radiation period versus WBRT alone. The primary endpoint was radiologic objective response at six weeks after the end of treatment, defined as a partial or complete response on systematic brain MRI (WHO modified criteria). We also evaluated neurologic symptoms, tolerance, safety, progression free survival (PFS) and overall survival (OS) as secondary endpoints. A longer clinical-brain MRI follow-up was planned, each three months during a two-year period. All of the patients gave their written informed consent to be part of the study, which was approved by the local committee.

Results: One hundred patients were enrolled between February 2008 and December 2010 (50 in the WBRT + TMZ arm, 50 in the WBRT arm). The median age was 55 [29 -79]. Eighty (80) patients had brain metastases as single secondary localization. About one third of patients had a triple negative breast cancer subtype (38,3% in the association arm and 35,71% in the WBRT alone arm). There were 26,7% and 14,6% of HER2 positive subtype respectively. The median follow-up was 30 months [range 6-60]. At six months from brain metastases diagnosis (three months after the end of the treatment), objective response rate seems better in the WBRT + TMZ arm: 52% versus 40% in the arm WBRT alone but was not statistically significant (p = 0,54). No complete response was observed. In the WBRT + TMZ group, median PFS and OS at six-months were respectively 55,6% [range 46-7 – 66,0] and 67,7% [range 59,1 – 77,6]. No improvement in neurologic symptoms was noticed. In multivariate analysis, initial TNM status was significantly correlated with PFS and OS. The concurrent use of TMZ with WBRT was well-tolerated. The most frequent upper grade II acute toxicity was reversible leucopenia in the association arm.

Conclusion: The addition of temozolomide to WBRT in patients with brain metastases from breast cancer did not improve local control or survival at six months follow-up.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P6-11-01.

Phylogenetic distinction of iNOS and IDO function in mesenchymal stem cell-mediated immunosuppression in mammalian species

Mammalian mesenchymal stem cells (MSCs) have been shown to be strongly immunosuppressive in both animal disease models and human clinical trials. We have reported that the key molecule mediating immunosuppression by MSCs is species dependent: indoleamine 2,3-dioxygenase (IDO) in human and inducible nitric oxide synthase (iNOS) in mouse. In the present study, we isolated MSCs from several mammalian species, each of a different genus, and investigated the involvement of IDO and iNOS during MSC-mediated immunosuppression. The characterization of MSCs from different species was by adherence to tissue culture plastic, morphology, specific marker expression, and differentiation potential. On the basis of the inducibility of IDO and iNOS by inflammatory cytokines in MSCs, the tested mammalian species fall into two distinct groups: IDO utilizers and iNOS utilizers. MSCs from monkey, pig, and human employ IDO to suppress immune responses, whereas MSCs from mouse, rat, rabbit, and hamster utilize iNOS. Interestingly, based on the limited number of species tested, the iNOS-utilizing species all belong to the phylogenetic clade, Glires. Although the evolutionary significance of this divergence is not known, we believe that this study provides critical guidance for choosing appropriate animal models for preclinical studies of MSCs.

Hypoxia induces osteogenesis in rabbit adipose-derived stem cells overexpressing bone morphogenic protein-2

OBJECTIVE

Hypoxic culture potentiates mesenchymal stem cells (MSCs) to survive and secrete various growth factors. Genetically modified stem cells overexpressing bone morphogenic protein-2 (BMP-2) demonstrate strong osteogenic ability. Hence, we investigated the coeffect of hypoxic culture conditions and BMP-2 overexpression on the osteogenic ability of rabbit adipose-derived stem cells (rASCs) in vitro.

MATERIALS AND METHODS

Rabbit adipose-derived stem cells with or without adenoviral-BMP-2 transduction were cultured in hypoxic (1%) and normoxic (21%) conditions. Cell viability, attachment, and proliferation were compared. Real-time PCR amplification of osteogenic and angiogenic genes including alkaline phosphatase (ALP), osteocalcin (OCN), HIF-1α, and vascular endothelial growth factor (VEGF) was performed. Moreover, ALP activity, immunofluorescent staining of OCN, and mineralization assay by alizarin red S quantification and von Kossa staining were conducted.

RESULTS

Cells under hypoxic conditions attached better within 12 h and proliferated faster. While BMP-2 overexpression and hypoxic condition separately elevated the transcription of key osteogenic and angiogenic genes, a cooperative effect was observed to enhance the upregulation of osteogenic as well as angiogenic genes. Identical changes were observed in ALP activity, immunofluorescent staining of OCN, and mineralization assay.

CONCLUSIONS

Hypoxic culture can enhance the osteogenic ability of BMP-2 gene-modified rASCs, which provides a strategy to improve the osteogenesis of rASCs for in vivo bone regeneration.

MnSb2O6: a polar magnet with a chiral crystal structure

Structural and magnetic chiralities are found to coexist in a small group of materials in which they produce intriguing phenomenologies such as the recently discovered Skyrmion phases. Here, we describe a previously unknown manifestation of this interplay in MnSb(2)O(6), a trigonal oxide with a chiral crystal structure. Unlike all other known cases, the MnSb(2)O(6) magnetic structure is based on corotating cycloids rather than helices. The coupling to the structural chirality is provided by a magnetic axial vector, related to the so-called vector chirality. We show that this unique arrangement is the magnetic ground state of the symmetric-exchange Hamiltonian, based on ab initio theoretical calculations of the Heisenberg exchange interactions, and is stabilized by out-of-plane anisotropy. MnSb(2)O(6) is predicted to be multiferroic with a unique ferroelectric switching mechanism.

The synergistic therapeutic effect of temozolomide and hyperbaric oxygen on glioma U251 cell lines is accompanied by alterations in vascular endothelial growth factor and multidrug resistance-associated protein-1 levels

OBJECTIVE

Temozolomide (TMZ) is an oral alkylating agent widely used in the treatment of refractory glioma. Its efficacy is limited, however, by poor cancer cell penetration and drug resistance. The present study, therefore, aimed to investigate whether hyperbaric oxygen (HBO) may facilitate drug delivery and enhance the anticancer effect of TMZ.

METHODS

Cultured glioma U251 cells were treated with HBO, TMZ, or TMZ + HBO, or were untreated (controls). Rates of growth inhibition, cell death and apoptosis were investigated using the 3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay, propidium iodide staining and flow cytometry, respectively. Protein levels of vascular endothelial growth factor (VEGF) and multidrug resistance-associated protein-1 (MRP-1) were evaluated by enzyme-linked immunosorbent assay.

RESULTS

Compared with TMZ or HBO alone, combined treatment with both therapies synergistically inhibited growth and induced apoptosis and death of cultured glioma U251 cells, which was accompanied by a significant decrease in levels of VEGF and MRP-1.

CONCLUSIONS

TMZ and HBO synergistically induced the apoptosis of glioma cells, possibly through reduced vascularization and inhibition of drug resistance. The combination of TMZ and HBO may be a powerful treatment for malignant glioma.

SU-D-BRB-05: Small Animal Lung Compliance Imaging: Assessment System for Tissue Sensitivity to Radiation Induced Lung Injury

PURPOSE

Recent clinical trials and animal studies have indicated that the tissue sensitivity to radiation induced lung injury (RILI) may be region- specific. In this study, we propose a new 4D cone beam CT (CBCT) basedcompliance imaging method to measure regional pulmonary function change in precisely irradiated small animal under CBCT guidance on small animal radiation research platform (SARRP) to facilitate our understanding of region-specific tissue sensitivity to RILI.

METHODS

Four Sprague-Dawley rats underwent prospective pressure gated 4D CBCT on SARRP. Three animals were selected as control group which underwent a second 4D CBCT scan. The fourth animal was irradiated in the central lung (24 Gy) using 3 × 3 mm collimating cone 2 months prior to the scan. The specific compliance (Csp) was calculated via the real time pressure measurement from the ventilator and displacement field from 3D B-spline image registration between the end of inhale and end of exhale phases from the 4D CBCT scan. The 3D Csp maps from the control animal group were mapped to the irradiated animal as a Csp functional atlas for statistical analysis. We alsoevaluated the repeatability of the Csp measurement on a voxel-by-voxel basis.

RESULTS

No significant Csp difference is found after two month of radiation between the irradiated rat (0.22±0.05) and the functional atlas (0.21±0.07). The observation is consistent with previous publications. The averaged linear correlation coefficient between the voxel-by-voxel Csp measurements from initial and repeat scans in control group is 0.98.

CONCLUSIONS

We proposed a method that uses 4D CBCT based compliance imaging to measure region-specific tissue sensitivity of RILI. We compared the irradiated animal two months after radiation with the control group. Our study shows an excellent robustness of the proposed method for regional lung tissue specific compliance measurement. This work was supported in part by UVa George Amorino Pilot Grant.

SU-E-J-192: Static Breath-Hold MRI Based Measurement of Change in Pulmonary Function Following a Course of Radiation Therapy

PURPOSE

Radiation Therapy (RT) induced pulmonary function change may depend on the location, underlying function of that lung prior to radiations, radiation dose/fractionation and other factors. We propose to evaluate the radiation induced pulmonary function change using static breath-hold MRI scans with vascular information and 3D deformable image registration which can provide pulmonary function relative to RT dose on a regional basis.

METHODS

A MRI scan pair near the end of inhale and near the end of exhale with breath hold were acquired for one lung cancer patient before RT and 6 months after RT. The patient was treated with SBRT with 55 Gy to PTVs in the right and the left lung respectively. B-spline based vesselness preserving image registration algorithm was applied to register the MRI pair for the calculation of local lung expansion as a measurement of regional pulmonary function (PF). The PF maps before RT and after RT were then mapped to the planning CT using the same algorithm tuned for MRI-CT registration. The pulmonary function change was calculated via the PF ratio between two MRI pairs.

RESULTS

Strong spatial correlation was found between the irradiated lung region and the region with greatly decreased PF. Based on dose and PFC distribution, no strong determinant factor was found for PF lost in the left lung while the right lung shows that all the lung tissue receiving dose larger than 28 Gy will have a decreased PF.

CONCLUSIONS

We demonstrated a method that uses static breath-hold MRI based lung imaging to evaluate radiation induced pulmonary function change which can be applied to study the dose and the pulmonary function change in a regional basis. This work is supported by NIH grant support 1R21CA144063.

SU-E-J-82: Improvement in Reproducibility of Lung Expansion Measures with Respiratory Effort Correction

PURPOSE

Longitudinal measurements of pulmonary function must account for subject variation when assessing radiation-induced changes. Previously, we reported intra-subject reproducibility of Jacobian-based measures of lung tissue expansion using repeat 4DCT scans prior to radiation therapy without correcting for differences in respiratory effort. In this study, we present two normalization schemes that correct ventilation images for variations in respiratory effort.

METHODS

Two repeat 4DCT image acquisitions were collected before treatment from seven patients. Using a tissue volume preserving deformable image registration algorithm, two Jacobian ventilation maps were computed from separate acquisitions. Two effort normalization strategies were investigated using intermediated inspiration phases upon the principles of equivalent tidal volume (ETV) and equivalent lung volume (ELV). Additional experiments were performed to verify the effectiveness of the ETV method. Scatter plots of two ventilation maps and statistical parameters of Jacobian ratio were compared before and after each effort correction approach.

RESULTS

The scatter plots of the ventilation maps show improvement in measurement reproducibility using either the ETV or ELV effort correction for all but one case. The one case that did not show improvement had a very similar lung volumes and tidal volumes in the two studies, so effort correction was unnecessary. The coefficient of variation (CV) of Jacobian ratio improved by 21±11 percent (mean±standard deviation) after ETV, and improved by 20±17 percent after ELV. Our experimental results on ETV show the decrease of tidal volume difference in two acquisitions improves reproducibility of lung expansion measures.

CONCLUSIONS

ETV and ELV correction methods improve the reproducibility of pulmonary function measurements in subjects that have differences in respiratory effort in the baseline and followup scans. Additional work is needed to investigate whether ETV or ELV is more effective, and to develop alternate regional normalization schemes that can account for difference in lung expansion rates.

Mesenchymal stem cells: a double-edged sword in regulating immune responses

Mesenchymal stem cells (MSCs) have been employed successfully to treat various immune disorders in animal models and clinical settings. Our previous studies have shown that MSCs can become highly immunosuppressive upon stimulation by inflammatory cytokines, an effect exerted through the concerted action of chemokines and nitric oxide (NO). Here, we show that MSCs can also enhance immune responses. This immune-promoting effect occurred when proinflammatory cytokines were inadequate to elicit sufficient NO production. When inducible nitric oxide synthase (iNOS) production was inhibited or genetically ablated, MSCs strongly enhance T-cell proliferation in vitro and the delayed-type hypersensitivity response in vivo. Furthermore, iNOS^−/− MSCs significantly inhibited melanoma growth. It is likely that in the absence of NO, chemokines act to promote immune responses. Indeed, in CCR5^−/−CXCR3^−/− mice, the immune-promoting effect of iNOS^−/− MSCs is greatly diminished. Thus, NO acts as a switch in MSC-mediated immunomodulation. More importantly, the dual effect on immune reactions was also observed in human MSCs, in which indoleamine 2,3-dioxygenase (IDO) acts as a switch. This study provides novel information about the pathophysiological roles of MSCs.