Effect of sunitinib combined with ionizing radiation on endothelial cells

Whole‑exome sequencing reveals Lewis lung carcinoma is a hypermutated Kras/Nras-mutant cancer with extensive regional mutation clusters in its genome

Lewis lung carcinoma (LLC), as a widely used preclinical cancer model, has still not been genetically and genomically characterized. Here, we performed a whole-exome sequencing analysis on the LLC cell line to elucidate its molecular characteristics and etiologies. Our data showed that LLC originated from a male mouse belonging to C57BL/6L (a transitional strain between C57BL/6J and C57BL/6N) and contains substantial somatic SNV and InDel mutations (> 20,000). Extensive regional mutation clusters are present in its genome, which were caused mainly by the mutational processes underlying the SBS1, SBS5, SBS15, SBS17a, and SBS21 signatures during frequent structural rearrangements. Thirty three deleterious mutations are present in 30 cancer genes including Kras, Nras, Trp53, Dcc, and Cacna1d. Cdkn2a and Cdkn2b are biallelically deleted from the genome. Five pathways (RTK/RAS, p53, cell cycle, TGFB, and Hippo) are oncogenically deregulated or affected. The major mutational processes in LLC include chromosomal instability, exposure to metabolic mutagens, spontaneous 5-methylcytosine deamination, defective DNA mismatch repair, and reactive oxygen species. Our data also suggest that LLC is a lung cancer similar to human lung adenocarcinoma. This study lays a molecular basis for the more targeted application of LLC in preclinical research.

Lycorine inhibits angiogenesis by docking to PDGFRα

Lycorine (Lyc) is a natural alkaloid derived from medicinal plants of the Amaryllidaceae family. Lyc has been reported to inhibit the recurrence and metastasis of different kinds of tumors. However, Lyc’s effect on angiogenesis and its specific mechanism are still not clear. This study was designed to test the antiangiogenesis effect of Lyc and to explore the possible mechanisms. We performed cell experiments to confirm Lyc’s inhibitory effect on angiogenesis and employed sunitinib as a positive control. Moreover, the synergistic effect of Lyc and sunitinib was also explored. Next, we conducted bioinformatics analyses to predict the potential targets of Lyc and verified them by western blotting and immunofluorescence. Molecular docking, kinase activity assays, Biacore assays and cellular thermal shift assays (CETSAs) were applied to elucidate the mechanism by which Lyc inhibited target activity. Lyc inhibited angiogenesis in human umbilical vein endothelial cells (HUVECs). Employing bioinformatics, we found that Lyc’s target was PDGFRα and that Lyc attenuated PDGFRα phosphorylation. We also found that Lyc inhibited PDGFRα activation by docking to it to restrain its activity. Additionally, Lyc significantly inhibited PDGF-AA-induced angiogenesis. This study provides new insights into the molecular functions of Lyc and indicates its potential as a therapeutic agent for tumor angiogenesis.

Radiobiological Studies of Microvascular Damage through In Vitro Models: A Methodological Perspective

Ionizing radiation (IR) is used in radiotherapy as a treatment to destroy cancer. Such treatment also affects other tissues, resulting in the so-called normal tissue complications. Endothelial cells (ECs) composing the microvasculature have essential roles in the microenvironment's homeostasis (ME). Thus, detrimental effects induced by irradiation on ECs can influence both the tumor and healthy tissue. In-vitro models can be advantageous to study these phenomena. In this systematic review, we analyzed in-vitro models of ECs subjected to IR. We highlighted the critical issues involved in the production, irradiation, and analysis of such radiobiological in-vitro models to study microvascular endothelial cells damage. For each step, we analyzed common methodologies and critical points required to obtain a reliable model. We identified the generation of a 3D environment for model production and the inclusion of heterogeneous cell populations for a reliable ME recapitulation. Additionally, we highlighted how essential information on the irradiation scheme, crucial to correlate better observed in vitro effects to the clinical scenario, are often neglected in the analyzed studies, limiting the translation of achieved results.

Impact of Tyrosine Kinase Inhibitors (TKIs) Combined With Radiation Therapy for the Management of Brain Metastases From Renal Cell Carcinoma

Background: Targeted therapy has transformed the outcome for patients with metastatic renal cell carcinoma. Their efficacy and safety have also been demonstrated in brain metastatic RCC. Preclinical evidence suggests synergism of radiation and tyrosine kinase inhibitors. Consequently, several studies have compared their efficacy in the treatment of RCC brain metastases to the era of brain management with surgery/radiation only.

Objectives: We seek to systematically review and meta-analyze the results of those studies that involved comparative intervention groups of brain management; TKIs, and never used TKIs.

Methods and Materials: Online databases (PubMed, EMBASE, Cochrane library, and ClinicalTrials.gov) were searched for comparative studies. Overall survival as the primary outcome of interest, and local brain control, distant control, and adverse events as secondary outcomes of interest were recorded for meta-analysis. Hazard ratios were pooled together using Review Manager 5.3. Fixed effects or random effects model were adopted according to the level of heterogeneity. Subgroup analysis included studies that involved SRS as the local treatment of management.

Results: Overall 7 studies (n = 897) were included for meta-analysis. TKI use was associated with better survival (HR 0.60 [0.52, 0.69], p < 0.00001) and local brain control (HR 0.34 [0.11, 0.98], p = 0.05). SRS subgroup also revealed significantly better survival (HR 0.61 [0.44, 0.83], p = 0.002) and local brain control (HR 0.19 [0.08, 0.45], p = 0.0002). Distant brain control (HR 0.95 [0.67, 1.35], p = 0.79) and brain progression free survival were unaffected (HR 0.94 [0.56, 1.56], p = 0.80). Only one study (n = 376) reported significantly greater 12-months cumulative incidence of radiation necrosis with TKI use within 30 days of SRS (10.9 vs. 6.4%, p = 0.04).

Conclusions: TKIs use in combination with SRS is safe and effective for treating RCC brain metastases. Larger randomized controlled trials are warranted to validate the results.

Overall survival and response to radiation and targeted therapies among patients with renal cell carcinoma brain metastases

OBJECTIVE

The object of this retrospective study was to investigate the impact of targeted therapies on overall survival (OS), distant intracranial failure, local failure, and radiation necrosis among patients treated with radiation therapy for renal cell carcinoma (RCC) metastases to the brain.

METHODS

All patients diagnosed with RCC brain metastasis (BM) between 1998 and 2015 at a single institution were included in this study. The primary outcome was OS, and secondary outcomes included local failure, distant intracranial failure, and radiation necrosis. The timing of targeted therapies was recorded. Multivariate Cox proportional-hazards regression was used to model OS, while multivariate competing-risks regression was used to model local failure, distant intracranial failure, and radiation necrosis, with death as a competing risk.

RESULTS

Three hundred seventy-six patients presented with 912 RCC BMs. Median OS was 9.7 months. Consistent with the previously validated diagnosis-specific graded prognostic assessment (DS-GPA) for RCC BM, Karnofsky Performance Status (KPS) and number of BMs were the only factors prognostic for OS. One hundred forty-seven patients (39%) received vascular endothelial growth factor receptor (VEGFR) tyrosine kinase inhibitors (TKIs). Median OS was significantly greater among patients receiving TKIs (16.8 vs 7.3 months, p < 0.001). Following multivariate analysis, KPS, number of metastases, and TKI use remained significantly associated with OS.The crude incidence of local failure was 14.9%, with a 12-month cumulative incidence of 13.4%. TKIs did not significantly decrease the 12-month cumulative incidence of local failure (11.4% vs 14.5%, p = 0.11). Following multivariate analysis, age, number of BMs, and lesion size remained associated with local failure. The 12-month cumulative incidence of radiation necrosis was 8.0%. Use of TKIs within 30 days of SRS was associated with a significantly increased 12-month cumulative incidence of radiation necrosis (10.9% vs 6.4%, p = 0.04).

CONCLUSIONS

Use of targeted therapies in patients with RCC BM treated with intracranial SRS was associated with improved OS. However, the use of TKIs within 30 days of SRS increases the rate of radiation necrosis without improving local control or reducing distant intracranial failure. Prospective studies are warranted to determine the optimal timing to reduce the rate of necrosis without detracting from survival.

Combination of novel systemic agents and radiotherapy for solid tumors - part I: An AIRO (Italian association of radiotherapy and clinical oncology) overview focused on treatment efficacy

Over the past century, technologic advances have promoted the evolution of radiation therapy into a precise treatment modality allowing for the maximal administration of dose to tumors while sparing normal tissues. In parallel with this technological maturation, the rapid expansion in understanding the basic biology and heterogeneity of cancer has led to the development of several compounds that target specific pathways. Many of them are in advanced steps of clinical development for combination treatments with radiotherapy, and can be incorporated into radiation oncology practice for a personalized approach to maximize the therapeutic gain. This review describes the rationale for combining novel agents with radiation, and provides an overview of the current landscape focused on treatment efficacy.

Radiotherapy and Vascular Endothelial Growth Factor Receptor-Tyrosine Kinase Inhibitors in Renal Cancer

Treatment of metastatic renal cell carcinoma (mRCC) has seen substantial progress over the last decade. A number of targeted therapies have been shown to improve clinical outcome. Vascular endothelial growth factor receptor (VEGFR)-tyrosine kinase inhibitors (TKIs) are an effective option in treating mRCC. RCC is traditionally perceived to be a radioresistant malignancy with a limited role of radiotherapy (RT) in the management of localized disease. While RCC appears to be radioresistant using conventionally fractionated RT, preclinical data suggest increased radiosensitivity when an ablative, hypofractionated schedule is used. RT is a common treatment for metastases; therefore, it is important to understand how best to use the combination of RT with targeted therapies. Preclinical studies have suggested that the combination of anti-angiogenic drugs with RT enhances the therapeutic effect compared with ionizing radiation alone. However, clinical data gave rise to warnings due to an increased incidence of severe gastrointestinal side effects. This article reviews the literature behind the preclinical and clinical data of the combination of RT with VEGFR-TKIs currently approved for RCC (sunitinib, sorafenib, pazopanib, and axitinib), with a focus on dose schedules as well as efficacy and toxicity.

Radiotherapy for Brain Metastases From Renal Cell Carcinoma in the Targeted Therapy Era: The University of Rochester Experience

OBJECTIVES

Radiotherapy remains the standard approach for brain metastases from renal cell carcinoma (RCC). Kinase inhibitors (KI) have become standard of care for metastatic RCC. They also increase the radiosensitivity of various tumor types in preclinical models. Data are lacking regarding the effect of KIs among RCC patients undergoing radiotherapy for brain metastases. We report our experience of radiotherapy for brain metastatic RCC in the era of targeted therapy and analyzed effects of concurrent KI therapy.

METHODS

We retrospectively analyzed 25 consecutive patients who received radiotherapy for brain metastases from RCC with whole-brain radiotherapy (WBRT), stereotactic radiosurgery (SRS), or both. Kaplan-Meier rates of overall survival (OS) and brain progression-free survival (BPFS) were calculated and univariate analyses performed.

RESULTS

Lower diagnosis-specific graded prognostic assessment (DS-GPA) score and multiple intracranial metastases were associated with decreased OS and BPFS on univariate analysis; DS-GPA is also a prognostic factor on multivariate analysis. There was no significant difference in OS or BPFS for SRS compared with WBRT or WBRT and SRS combined. The concurrent use of KI was not associated with any change in OS or BPFS.

CONCLUSIONS

This hypothesis-generating analysis suggests among patients with brain metastatic RCC treated with the most current therapies, those selected to undergo SRS did not experience significantly different survival or control outcomes than those selected to undergo WBRT. From our experience to date, limited in patient numbers, there seems to be neither harm nor benefit in using concurrent KI therapy during radiotherapy. Given that most patients progress systemically, we would recommend considering KI use during brain radiotherapy in these patients.

Cardiovascular diseases related to ionizing radiation: The risk of low-dose exposure (Review)

Traditionally, non-cancer diseases are not considered as health risks following exposure to low doses of ionizing radiation. Indeed, non-cancer diseases are classified as deterministic tissue reactions, which are characterized by a threshold dose. It is judged that below an absorbed dose of 100 mGy, no clinically relevant tissue damage occurs, forming the basis for the current radiation protection system concerning non-cancer effects. Recent epidemiological findings point, however, to an excess risk of non-cancer diseases following exposure to lower doses of ionizing radiation than was previously thought. The evidence is the most sound for cardiovascular disease (CVD) and cataract. Due to limited statistical power, the dose-risk relationship is undetermined below 0.5 Gy; however, if this relationship proves to be without a threshold, it may have considerable impact on current low-dose health risk estimates. In this review, we describe the CVD risk related to low doses of ionizing radiation, the clinical manifestation and the pathology of radiation-induced CVD, as well as the importance of the endothelium models in CVD research as a way forward to complement the epidemiological data with the underlying biological and molecular mechanisms.

Radiation-Therapeutic Agent Clinical Trials: Leveraging Advantages of a National Cancer Institute Programmatic Collaboration

A number of oncology phase II radiochemotherapy trials with promising results have been conducted late in the overall experimental therapeutic agent development process. Accelerated development and approval of experimental therapeutic agents have stimulated further interest in much earlier radiation-agent studies to increase the likelihood of success in phase III trials. To sustain this interest, more forward-thinking preclinical radiobiology experimental designs are needed to improve discovery of promising radiochemotherapy plus agent combinations for clinical trial testing. These experimental designs should better inform next-step radiation-agent clinical trial dose, schedule, exposure, and therapeutic effect. Recognizing the need for a better strategy to develop preclinical data supporting radiation-agent phase I or II trials, the National Cancer Institute (NCI)-Cancer Therapy Evaluation Program (CTEP) and the NCI-Molecular Radiation Therapeutics Branch of the Radiation Research Program have partnered to promote earlier radiobiology studies of CTEP portfolio agents. In this Seminars in Radiation Oncology article, four key components of this effort are discussed. First, we outline steps for accessing CTEP agents for preclinical testing. Second, we propose radiobiology studies that facilitate transition from preclinical testing to early phase trial activation. Third, we navigate steps that walk through CTEP agent strategic development paths available for radiation-agent testing. Fourth, we highlight a new NCI-sponsored cooperative agreement grant supporting in vitro and in vivo radiation-CTEP agent testing that informs early phase trial designs. Throughout the article, we include contemporary examples of successful radiation-agent development initiatives.

Assessment of tumor response to radiation and vascular targeting therapy in mice using quantitative ultrasound spectroscopy

PURPOSE

It is now recognized that the tumor vasculature is in part responsible for regulating tumor responses to radiation therapy. However, the extent to which radiation-based vascular damage contributes to tumor cell death remains unknown. In this work, quantitative ultrasound spectroscopy (QUS) methods were used to investigate the acute responses of tumors to radiation-based vascular treatments.

METHODS

Tumor xenografts (MDA-MB-231) were treated with single radiation doses of 2 or 8 Gy alone, or in combination with pharmacological agents that modulate vascular radiosensitivity. The midband fit, the slope, and the 0-MHz intercept QUS parameters were obtained from a linear-regression fit to the averaged power spectrum of frequency-dependent ultrasound backscatter and were used to quantify acute tumor responses following treatment administration. Power spectrums were extracted from raw volumetric radio-frequency ultrasound data obtained before and 24 h following treatment administration. These parameters have previously been correlated to tumor cell death. Staining using in situ end labeling, carbonic anhydrase 9 and cluster of differentiation 31 of tumor sections were used to assess cell death, oxygenation, and vasculature distributions, respectively.

RESULTS

Results indicate a significant midband fit QUS parameter increases of 3.2 ± 0.3 dBr and 5.4 ± 0.5 dBr for tumors treated with 2 and 8 Gy radiation combined with the antiangiogenic agent Sunitinib, respectively. In contrast, tumors treated with radiation alone demonstrated a significant midband fit increase of 4.4 ± 0.3 dBr at 8 Gy only. Preadministration of basic fibroblast growth factor, an endothelial radioprotector, acted to minimize tumor response following single large doses of radiation. Immunohistochemical analysis was in general agreement with QUS findings; an R(2) of 0.9 was observed when quantified cell death was correlated with changes in midband fit.

CONCLUSIONS

Results from QUS analysis presented in this study confirm that acute tumor response is linked to a vascular effect following high doses of radiation therapy. Overall, this is in agreement with previous reports suggesting that acute tumor radiation response is regulated by a vascular-driven response. Data also suggest that Sunitinib may enhance tumor radiosensitivity through a vascular remodeling process, and that QUS may be sensitive to changes in tissue properties associated with vascular remodeling. Finally, the work also demonstrates the ability of QUS methods to monitor response to radiation-based vascular strategies.

Famitinib enhances nasopharyngeal cancer cell radiosensitivity by attenuating radiation-induced phosphorylation of platelet-derived growth factor receptor and c-kit and inhibiting microvessel formation

PURPOSE

Famitinib is a novel tyrosine kinase inhibitor. We investigated the effects of famitinib on the radiosensitivity of human nasopharyngeal carcinoma (NPC) cell radiosensitivity in vitro and in vivo, and explored its possible mechanisms.

MATERIALS AND METHODS

Human nasopharyngeal carcinoma cell line (CNE-2) were treated with famitinib and radiation, and analyzed by3-(4,5-dimethylthaizol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), clonogenic survival assay, and Western blot. A xenograft model using CNE-2 cells was established to analyze the effects of famitinib and radiation on tumor volume and microvessel density (MVD).

RESULTS

Famitinib dose-dependently inhibited CNE-2 cells growth and significantly reduced clonogenic survival (p < 0.05), with a sensitivity enhancement ratio (SER) of 1.45. The tumor inhibition rate of the combined treatment group was 91%, which was significantly higher than the radiation group (35%, p < 0.05) and famitinib group (46%, p < 0.05). Famitinib attenuated radiation-induced phosphorylation of the platelet-derived growth factor receptor (PDGFR) and stem cell factor (c-kit) at 0, 30, 60 min after radiation treatment. Furthermore, radiation combined with famitinib decreased tumor MVD (p < 0.05).

CONCLUSIONS

Famitinib significantly increased CNE-2 cell radiosensitivity in vitro and in vivo by attenuating radiation-induced PDGFR and c-kit phosphorylation and by inhibiting microvessel formation.

Radiation therapy following targeted therapy in oligometastatic renal cell carcinoma

Up to 40% of patients with renal cell carcinoma (RCC) with initially localized disease eventually develop metastasis following nephrectomy. The current standard of care for metastatic RCC (mRCC) is targeted therapy. However, complete response remains rare. A state of oligometastatic disease may exist, in which metastases are present in a limited number of locations; such cases may benefit from metastasis-directed local therapy, based on the evidence supporting resection of limited-volume metastases, allowing for improved disease control. We retrospectively analyzed 7 cases of response of RCC metastases, in patients treated with targeted therapies followed by radiation therapy (RT) of residual metastatic lesions in Paoli-Calmettes Institute (Marseille, France). We analyzed disease response rates, response to sequential strategy, relapse at the irradiated locations and disease evolution. The median follow-up was 34.1 months (range, 19.2-54.5 months). No progression at the irradiated sites was observed. A total of 5 patients had stable disease at the irradiated locations at the last follow-up; 3 remained in complete remission at the assessment, and 2 were stable. Excellent local response and clinical benefit may be achieved without added toxicity. In conclusion, sequential therapeutic strategies with RT following systemic treatment using sunitinib appear to be highly effective in patients with progressive mRCC and prompt the conduction of further confirmatory trials.

Combining radiotherapy with sunitinib: lessons (to be) learned

To improve the efficacy of radiotherapy (RTx), there is a growing interest in combining RTx with drugs that inhibit angiogenesis, i.e., the process of neo-vessel formation out of preexisting capillaries. A frequently used drug to inhibit angiogenesis is sunitinib (Sutent, SU11248), a receptor tyrosine kinase inhibitor that is currently FDA approved for the treatment of several cancer types. The current review presents an overview of the preclinical studies and clinical trials that combined sunitinib with RTx. We discuss the findings from preclinical and clinical observations with a focus on dose scheduling and commonly reported toxicities. In addition, the effects of combination therapy on tumor response and patient survival are described. Finally, the lessons learned from preclinical and clinical studies are summarized and opportunities and pitfalls for future clinical trials are presented.

Anticancer effect of tectochrysin in colon cancer cell via suppression of NF-kappaB activity and enhancement of death receptor expression

Background

Flavonoids are a diverse family of natural phenolic compounds commonly found in fruits and vegetables. Epidemiologic studies showed that flavonoids also reduce the risk of colon cancer. Tectochrysin is one of the major flavonoids of Alpinia oxyphylla Miquel. However, the anti-cancer effects and the molecular mechanisms of tectochrysin in colon cancer cells have not yet been reported. We investigated whether tectochrysin could inhibit colon cancer cell growth at 1, 5, 10 μg/ml. In in vivo study, we injected a tectochrysin treatment dose of 5 mg/kg to each mouse.

Results

Tectochrysin suppressed the growth of SW480 and HCT116 human colon cancer cells. The expression of DR3, DR4 and Fas were significantly increased, and pro-apoptotic proteins were also increased. Tectochrysin treatment also inhibited activity of NF-κB. A docking model indicated that tectochrysin binds directly to the p50 unit. In in vivo, tumor weights and volumes in mice were reduced when treated with tectochrysin. Tectochrysin leads to apoptotic cell death in colon cancer cells through activation of death receptors expression via the inhibition of NF-κB.

Conclusions

Tectochrysin can be a useful agent for the treatment of colon cancer cell growth as well as an adjuvant agent for chemo-resistant cancer cells growth.

Myeloid-Derived Suppressor Cells as an Immune Parameter in Patients with Concurrent Sunitinib and Stereotactic Body Radiotherapy

PURPOSE

The clinical effects of sunitinib on human myeloid-derived suppressor cell (MDSC) subsets and correlation of the T-cell-mediated immune responses and clinical outcomes in patients with oligometastases treated by stereotactic body radiotherapy (SBRT) have been evaluated.

EXPERIMENTAL DESIGN

The numbers of granulocytic and monocytic MDSC subsets, effector T cells, and regulatory T cells in the peripheral blood were evaluated pre- and post-sunitinib treatment and concurrent with SBRT. Correlations between MDSC, Treg, and T-cell responses and clinical outcomes were analyzed.

RESULTS

Patients with oligometastases of various cancer types had elevated granulocytic MDSC and certain subsets of monocytic MDSC population. Sunitinib treatment resulted in a significant reduction in monocytic MDSC, phosphorylated STAT3, and arginase levels in monocytic MDSC (CD33(+)CD14(+)CD16(+)), and an increase in T-cell proliferative activity in cancer patients. Interestingly, the effects of sunitinib on reducing the accumulation and immune-suppressive function of MDSC were significantly correlated with Treg reduction, in responders but not in nonresponding patients. SBRT synergized the therapeutic effects of sunitinib, especially as related to decreased numbers of monocytic MDSC, Treg, and B cells, and augmented Tbet expression in primary CD4 and CD8 T cells. These effects were not observed in patients receiving radiation therapy alone. Most interestingly, the responders, defined by sunitinib-mediated reduction in CD33(+)CD11b(+) myeloid cell populations, tend to exhibit improved progression-free survival and cause-specific survival.

CONCLUSIONS

Sunitinib treatment increased the efficacy of SBRT in patients with oligometastases by reversing MDSC and Treg-mediated immune suppression and may enhance cancer immune therapy to prevent tumor recurrence post-SBRT.

Optimal treatment scheduling of ionizing radiation and sunitinib improves the antitumor activity and allows dose reduction

The combination of radiotherapy with sunitinib is clinically hampered by rare but severe side effects and varying results with respect to clinical benefit. We studied different scheduling regimes and dose reduction in sunitinib and radiotherapy in preclinical tumor models to improve potential outcome of this combination treatment strategy. The chicken chorioallantoic membrane (CAM) was used as an angiogenesis in vivo model and as a xenograft model with human tumor cells (HT29 colorectal adenocarcinoma, OE19 esophageal adenocarcinoma). Treatment consisted of ionizing radiation (IR) and sunitinib as single therapy or in combination, using different dose-scheduling regimes. Sunitinib potentiated the inhibitory effect of IR (4 Gy) on angiogenesis. In addition, IR (4 Gy) and sunitinib (4 days of 32.5 mg/kg per day) inhibited tumor growth. Ionizing radiation induced tumor cell apoptosis and reduced proliferation, whereas sunitinib decreased tumor angiogenesis and reduced tumor cell proliferation. When IR was applied before sunitinib, this almost completely inhibited tumor growth, whereas concurrent IR was less effective and IR after sunitinib had no additional effect on tumor growth. Moreover, optimal scheduling allowed a 50% dose reduction in sunitinib while maintaining comparable antitumor effects. This study shows that the therapeutic efficacy of combination therapy improves when proper dose-scheduling is applied. More importantly, optimal treatment regimes permit dose reductions in the angiogenesis inhibitor, which will likely reduce the side effects of combination therapy in the clinical setting. Our study provides important leads to optimize combination treatment in the clinical setting.

(E)-2,4-Bis(p-hydroxyphenyl)-2-butenal inhibits tumor growth via suppression of NF-κB and induction of death receptor 6

The Maillard reaction products are known to be effective in chemoprevention. Here, we focused on the anti-cancer effects of (E)-2,4-bis(p-hydroxyphenyl)-2-butenal on in vitro and in vivo colon cancer. We analysed the anti-cancer activity of (E)-2,4-bis(p-hydroxyphenyl)-2-butenal on colon cancer cells by using cell cycle and apoptosis analysis. To elucidate it's mechanism, NF-κB DNA binding activity, docking model as well as pull-down assay. Further, a xenograft model of colon cancer was studied to test the in vivo effects of (E)-2,4-bis(p-hydroxyphenyl)-2-butenal. (E)-2,4-Bis(p-hydroxyphenyl)-2-butenal inhibited colon cancer cells (SW620 and HCT116) growth followed by induction of apoptosis in a concentration-dependent manner via down-regulation of NF-κB activity. In docking model as well as pull-down assay, (E)-2,4-bis(p-hydroxyphenyl)-2-butenal directly binds to three amino acid residues of IKKβ, thereby inhibited IKKβ activity in addition to induction of death receptor 6 (DR6) as well as their target apoptotic genes. Finally, (E)-2,4-bis(p-hydroxyphenyl)-2-butenal suppressed anchorage-independent cancer cell growth, and tumor growth in xenograft model accompanied with apoptosis through inhibition of IKKβ/NF-κB activity, and overexpression of DR6. These results suggest that (E)-2,4-bis(p-hydroxyphenyl)-2-butenal inhibits colon cancer cell growth through inhibition of IKKβ/NF-κB activity and induction of DR6 expression.

Melittin radiosensitizes esophageal squamous cell carcinoma with induction of apoptosis in vitro and in vivo

Currently, unresectable esophageal squamous cell carcinoma (ESCC) is primarily treated by chemoradiotherapy. However, the outcome has not improved significantly because of radioresistance of cancer cells. This study aimed to determine the radiosensitizing effect of melittin, a novel component of bee venom, in ESCC. ESCC cell lines were irradiated with or without melittin. Cell proliferation was detected by Cell Counting Kit 8 assay. Radiosensitization was evaluated by clonogenic survival assay. Cell apoptosis was detected by flow cytometry. Results show that melittin potently sensitized ESCC cells to radiation with a sensitization enhancement ratio of 1.15-1.42. Radiosensitization was accompanied with enhanced apoptosis and regulated by apoptosis proteins. The results were confirmed by in vivo studies on tumor-bearing xenografts. In summary, these results provide support that melittin may be a potentially promising radiosensitizer in ESCC radiation therapy.

Enhanced Anti-Cancer Effect of Snake Venom Activated NK Cells on Lung Cancer Cells by Inactivation of NF-κB

In the present study, we investigated anti-cancer effect of snake venom activated NK cells (NK-92MI) in lung cancer cell lines. We used snake venom (4 μg/ml) treated NK-92MI cells to co-culture with lung cancer cells. There was a further decrease in cancer cell growth up to 65% and 70% in A549 and NCI-H460 cell lines respectively, whereas 30–40% was decreased in cancer cell growth by snake venom or NK-92MI alone treatment. We further found that the expression of various apoptotic proteins such as that Bax, and cleaved caspase-3 as well as the expression of various death receptor proteins like DR3, DR4 and Fas was also further increased. Moreover, consistent with cancer cell growth inhibition, the DNA binding activity of NF-κB was also further inhibited after treatment of snake venom activated NK-92MI cells. Thus, the present data showed that activated NK cells could further inhibit lung cancer cell growth.

Sunitinib administered prior to radiotherapy in patients with non-resectable glioblastoma: results of a phase II study

Sunitinib is a tyrosine kinase inhibitor with direct anti-tumor and anti-angiogenesis activity targeting VEGFR 1-2, PDGFR α-β, c-kit, bFGF, (CSF-1), FLT3 and RET. The present trial examined the activity of sunitinib in 12 patients with newly diagnosed, non-resectable glioblastoma. Patients (≤75 years of age with performance status [PS] ≥2 and minimental status [MMS] ≥25) were treated post-biopsy with sunitinib 37.5 mg daily for 8 weeks pre-radiotherapy, during radiotherapy (60 Gy, 6 weeks) and post-radiotherapy until disease progression. The primary endpoints were overall response rate (ORR; RANO criteria) after 8 weeks of sunitinib and patient tolerance. Secondary endpoints were percentage of patients free of neurological deterioration pre-radiotherapy, percentage of patients completing radiotherapy, progression-free survival (PFS), overall survival (OS), and 1-year survival. A Simon 2-stage design (12 →20) based on ORR was applied to calculate the number of patients needed to detect at least 10 % response with α error of 0.05 and β error of 0.10. The trial was closed because it did not meet minimal activity criteria. ORR was 0 % with only 1/12 patients (8.3 %) achieving stable disease after sunitinib treatment. No patient showed reduction in gadolinium enhancement. The most frequent G3/4 toxicities were fatigue (24.9 %) and diarrhea (16.6 %); one patient died of a CNS hemorrhage; 10/12 patients (83.3 %) deteriorated neurologically before radiation therapy; median PFS was 7.7 weeks (95 % CI: 7.2-8.2); median OS was 12.8 weeks (95 % CI: 0.5-23.8 weeks); 1-year survival was 0 %. Sunitinib has no activity as monotherapy in glioblastoma, and further investigation of its efficacy in this setting is unwarranted.

Co-culture with NK-92MI cells enhanced the anti-cancer effect of bee venom on NSCLC cells by inactivation of NF-κB

In the present study we experimented on a multimodal therapeutic approach, such as combining chemotherapy agent (Bee venom) with cellular (NK-92MI) immunotherapy. Previously bee venom has been found to show anti-cancer effect in various cancer cell lines. In lung cancer cells bee venom showed an IC(50) value of 3 μg/ml in both cell lines. The co-culture of NK-92MI cell lines with lung cancer cells also show a decrease in viability upto 50 % at 48 h time point. Hence we used bee venom treated NK-92MI cells to co-culture with NSCLC cells and found that there is a further decrease in cell viability upto 70 and 75 % in A549 and NCI-H460 cell lines respectively. We further investigated the expression of various apoptotic and anti-apoptotic proteins and found that Bax, cleaved caspase-3 and -8 were increasing where as Bcl-2 and cIAP-2 was decreasing. The expression of various death receptor proteins like DR3, DR6 and Fas was also increasing. Concomitantly the expression of various death receptor ligands (TNFalpha, Apo3L and FasL) was also increasing of NK-92MI cells after co-culture. Further the DNA binding activity and luciferase activity of NF-κB was also inhibited after co-culture with bee venom treated NK-92MI cell lines. The knock down of death receptors with si-RNA has reversed the decrease in cell viability and NF-κB activity after co-culture with bee venom treated NK-92MI cells. Thus this new approach can enhance the anti-cancer effect of bee venom at a much lower concentration.

Sunitinib effects on the radiation response of endothelial and breast tumor cells

BACKGROUND

Endothelial cells are suggested regulators of tumor response to radiation. Anti-vascular targeting agents can enhance tumor response by targeting endothelial cells. Here, we have conducted experiments in vitro to discern the effects of radiation combined with the anti-angiogenic Sunitinib on endothelial (HUVEC) and tumor (MDA-MB-231) cells, and further compared findings to results obtained in vivo.

METHODS

In vitro and in vivo treatments consisted of single dose radiation therapy of 2, 4, 8 or 16 Gy administered alone or in combination with bFGF or Sunitinib. In vitro, in situ end labeling (ISEL) was used to assess 24-hour apoptotic cell death, and clonogenic assays were used to assess long-term response. In vivo MDA-MB-231 tumors were grown in CB-17 SCID mice. The vascular marker CD31 was used to assess 24-hour acute response while tumor clonogenic assays were used to assess long-term tumor cell viability following treatments.

RESULTS

Using in vitro studies, we observed an enhanced endothelial cell response to radiation doses of 8 and 16 Gy when compared to tumor cells. Administering Sunitinib alone significantly increased HUVEC cell death, while having modest additive effects when combined with radiation. Sunitinib also increased tumor cell death when combined with 8 and 16 Gy radiation doses. In comparison, we found that the clonogenic response of in vivo treated tumor cells more closely resembled that of in vitro treated endothelial cells than in vitro treated tumor cells.

CONCLUSION

Our results indicate that the endothelium is an important regulator of tumor response to radiotherapy, and that Sunitinib can enhance tumor radiosensitivity. To the best of our knowledge, this is the first time that Sunitinib is investigated in combination with radiotherapy on the MDA-MB-231 breast cancer cell line.

Variations of circulating endothelial progenitor cells and transforming growth factor-beta-1 (TGF-β1) during thoracic radiotherapy are predictive for radiation pneumonitis

Background

The vascular endothelial cells are important targets of radiotherapy, which may be involved in the pathogenesis of radiation pneumonitis (RP). This study investigated the variations of circulating endothelial progenitor cells (EPCs) and transforming growth factor-beta-1 (TGF-β1) during three-dimensional conformal radiation therapy (3D-CRT) in patients with non–small-cell lung cancer (NSCLC) and analyzed the correlation between these variations with the occurrence of RP.

Patients and methods

From November 2008 to November 2009, eighty-four consecutive patients receiving 3D-CRT for stage III disease were evaluated prospectively. Circulating EPCs and TGF-β1 levels were measured at baseline, every 2 weeks during, and at the end of treatment. RP was evaluated prospectively at 6 weeks after 3D-CRT.

Results

Thirty-eight patients (47.5%) experienced score 1 or more of RP. The baseline levels of EPCs and TGF-β1 were analyzed, no difference was found between patients with and without RP during and after 3D-CRT. By serial measurement of TGF-β1 and EPCs levels, we found that the mean levels of EPCs in the whole population remained stable during radiotherapy, but the mean levels of TGF-β1 increased slowly during radiotherapy. TGF-β1 and EPCs levels were all significantly higher at week 2, week 4 and week 6 in patients with RP than that in patients without RP, respectively. During the period of radiation treatment, TGF-β1 levels began to increase in the first 2 weeks and became significantly higher at week 6 (P < 0.01). EPCs levels also began to increase in the first 2 weeks and reached a peak at week 4. Using an ANOVA model for repeated-measures, we found significant associations between the levels of TGF-β1 and EPCs during the course of 3D-CRT and the risk of developing RP (P < 0.01). Most of the dosimetric factors showed a significant association with RP.

Conclusion

Early variations of TGF-β1 and EPCs levels during 3D-CRT are significantly associated with the risk of RP. Variations of circulating TGF-β1 and EPCs levels during 3D-CRT may serve as independent predictive factors for RP.

Trial registration

Trials registration number: 20070618

Differential response to acute low dose radiation in primary and immortalized endothelial cells

PURPOSE

The low dose radiation response of primary human umbilical vein endothelial cells (HUVEC) and its immortalized derivative, the EA.hy926 cell line, was evaluated and compared.

MATERIAL AND METHODS

DNA damage and repair, cell cycle progression, apoptosis and cellular morphology in HUVEC and EA.hy926 were evaluated after exposure to low (0.05-0.5 Gy) and high doses (2 and 5 Gy) of acute X-rays.

RESULTS

Subtle, but significant increases in DNA double-strand breaks (DSB) were observed in HUVEC and EA.hy926 30 min after low dose irradiation (0.05 Gy). Compared to high dose irradiation (2 Gy), relatively more DSB/Gy were formed after low dose irradiation. Also, we observed a dose-dependent increase in apoptotic cells, down to 0.5 Gy in HUVEC and 0.1 Gy in EA.hy926 cells. Furthermore, radiation induced significantly more apoptosis in EA.hy926 compared to HUVEC.

CONCLUSIONS

We demonstrated for the first time that acute low doses of X-rays induce DNA damage and apoptosis in endothelial cells. Our results point to a non-linear dose-response relationship for DSB formation in endothelial cells. Furthermore, the observed difference in radiation-induced apoptosis points to a higher radiosensitivity of EA.hy926 compared to HUVEC, which should be taken into account when using these cells as models for studying the endothelium radiation response.

Evaluation of poly-mechanistic antiangiogenic combinations to enhance cytotoxic therapy response in pancreatic cancer

Gemcitabine (Gem) has limited clinical benefits in pancreatic ductal adenocarcinoma (PDAC). The present study investigated combinations of gemcitabine with antiangiogenic agents of various mechanisms for PDAC, including bevacizumab (Bev), sunitinib (Su) and EMAP II. Cell proliferation and protein expression were analyzed by WST-1 assay and Western blotting. In vivo experiments were performed via murine xenografts. Inhibition of in vitro proliferation of AsPC-1 PDAC cells by gemcitabine (10 µM), bevacizumab (1 mg/ml), sunitinib (10 µM) and EMAP (10 µM) was 35, 22, 81 and 6 percent; combination of gemcitabine with bevacizumab, sunitinib or EMAP had no additive effects. In endothelial HUVECs, gemcitabine, bevacizumab, sunitinib and EMAP caused 70, 41, 86 and 67 percent inhibition, while combination of gemcitabine with bevacizumab, sunitinib or EMAP had additive effects. In WI-38 fibroblasts, gemcitabine, bevacizumab, sunitinib and EMAP caused 79, 58, 80 and 29 percent inhibition, with additive effects in combination as well. Net in vivo tumor growth inhibition in gemcitabine, bevacizumab, sunitinib and EMAP monotherapy was 43, 38, 94 and 46 percent; dual combinations of Gem+Bev, Gem+Su and Gem+EMAP led to 69, 99 and 64 percent inhibition. Combinations of more than one antiangiogenic agent with gemcitabine were generally more effective but not superior to Gem+Su. Intratumoral proliferation, apoptosis and microvessel density findings correlated with tumor growth inhibition data. Median animal survival was increased by gemcitabine (26 days) but not by bevacizumab, sunitinib or EMAP monotherapy compared to controls (19 days). Gemcitabine combinations with bevacizumab, sunitinib or EMAP improved survival to similar extent (36 or 37 days). Combinations of gemcitabine with Bev+EMAP (43 days) or with Bev+Su+EMAP (46 days) led to the maximum survival benefit observed. Combination of antiangiogenic agents improves gemcitabine response, with sunitinib inducing the strongest effect. These findings demonstrate advantages of combining multi-targeting agents with standard gemcitabine therapy for PDAC.

Combination of nitric oxide stimulation with high-dose 18F-FDG promotes apoptosis and enhances radiation therapy of endothelial cells

INTRODUCTION

High-dose (18)F-FDG can provide targeted nuclear therapy of cancer. Endothelial cell injury is a key determinant of tumor response to radiotherapy. Here, we tested the hypothesis that activation of endothelial cell glycolytic metabolism with nitric oxide can enhance the therapeutic effect of high-dose (18)F-FDG.

METHODS

Calf pulmonary artery endothelial (CPAE) cells were treated with graded doses of (18)F-FDG. Glycolysis was stimulated by 24 h of exposure to the nitric oxide donor, sodium nitroprusside (SNP). Cell viability was assessed by MTT and clonogenic assays. Apoptosis was evaluated by ELISA of cytosolic DNA fragments and Western blots of cleaved caspase-3.

RESULTS

SNP stimulation (0.1 and 1 mM) augmented CPAE cell (18)F-FDG uptake to 2.6- and 4.6-fold of controls without adverse effects. Treatment with 333 μCi/ml (18)F-FDG alone reduced viable cell number to 35.4% of controls by Day 3. Combining 0.1 mM SNP stimulation significantly enhanced the killing effect, reducing cell numbers to 19.2% and 39.2% of controls by 333 and 167 μCi/ml of (18)F-FDG, respectively. (18)F-FDG also suppressed clonogenic survival to 80.8% and 43.2% of controls by 83 and 167 μCi/ml, which was again intensified by SNP to 59.7% and 21.1% of controls. The cytotoxic effect of (18)F-FDG was attributed to induction of apoptosis as shown by increased cytosolic fragmented DNA and cleaved caspase-3 levels (26.4% and 30.7% increases by 167 μCi/ml). Combining SNP stimulation significantly increased both of these levels to 1.8-fold of control cells.

CONCLUSION

High-dose (18)F-FDG combined with nitric oxide-stimulated glycolysis is an effective method to inhibit endothelial cell survival and promote apoptosis. These results suggest a potential role of this strategy for targeted radiotherapy of angiogenic vasculature.

Anti-cancer effect of bee venom toxin and melittin in ovarian cancer cells through induction of death receptors and inhibition of JAK2/STAT3 pathway

We investigated whether bee venom and melittin, a major component of bee venom, inhibit cell growth through enhancement of death receptor expressions in the human ovarian cancer cells, SKOV3 and PA-1. Bee venom (1-5 μg/ml) and melittin (0.5-2 μg/ml) inhibited the growth of SKOV3 and PA-1 ovarian cancer cells by the induction of apoptotic cell death in a dose dependent manner. Consistent with apoptotic cell death, expression of death receptor (DR) 3 and DR6 was increased in both cancer cells, but expression of DR4 was increased only in PA-1 cells. Expression of DR downstream pro-apoptotic proteins including caspase-3, 8, and Bax was concomitantly increased, but the phosphorylation of JAK2 and STAT3 and the expression of Bcl-2 were inhibited by treatment with bee venom and melittin in SKOV3 and PA-1 cells. Expression of cleaved caspase-3 was increased in SKOV3, but cleaved caspase-8 was increased in PA-1 cells. Moreover, deletion of DR3, DR4, and DR6 by small interfering RNA significantly reversed bee venom and melittin-induced cell growth inhibitory effect as well as down regulation of STAT3 by bee venom and melittin in SKOV3 and PA-1 ovarian cancer cell. These results suggest that bee venom and melittin induce apoptotic cell death in ovarian cancer cells through enhancement of DR3, DR4, and DR6 expression and inhibition of STAT3 pathway.