Correlation between tumor growth delay and expression of cancer and host VEGF, VEGFR2, and osteopontin in response to radiotherapy

The radiation- and chemo-sensitizing capacity of diclofenac can be predicted by a decreased lactate metabolism and stress response

BACKGROUND

An enhanced aerobic glycolysis ("Warburg effect") associated with an increase in lactic acid in the tumor microenvironment contributes to tumor aggressiveness and resistance to radiation and chemotherapy. We investigated the radiation- and chemo-sensitizing effects of the nonsteroidal anti-inflammatory drug (NSAID) diclofenac in different cancer cell types.

METHODS

The effects of a non-lethal concentration of diclofenac was investigated on c-MYC and Lactate Dehydrogenase (LDH) protein expression/activity and the Heat shock Protein (HSP)/stress response in human colorectal (LS174T, LoVo), lung (A549), breast (MDA-MB-231) and pancreatic (COLO357) carcinoma cells. Radiation- and chemo-sensitization of diclofenac was determined using clonogenic cell survival assays and a murine xenograft tumor model.

RESULTS

A non-lethal concentration of diclofenac decreases c-MYC protein expression and LDH activity, reduces cytosolic Heat Shock Factor 1 (HSF1), Hsp70 and Hsp27 levels and membrane Hsp70 positivity in LS174T and LoVo colorectal cancer cells, but not in A549 lung carcinoma cells, MDA-MB-231 breast cancer cells and COLO357 pancreatic adenocarcinoma cells. The impaired lactate metabolism and stress response in diclofenac-sensitive colorectal cancer cells was associated with a significantly increased sensitivity to radiation and 5Fluorouracil in vitro, and in a human colorectal cancer xenograft mouse model diclofenac causes radiosensitization.

CONCLUSION

These findings suggest that a decrease in the LDH activity and/or stress response upon diclofenac treatment predicts its radiation/chemo-sensitizing capacity.

The Radiosensitizing Potentials of Silymarin/Silibinin in Cancer: A Systematic Review

INTRODUCTION

Although radiotherapy is one of the main cancer treatment modalities, exposing healthy organs/tissues to ionizing radiation during treatment and tumor resistance to ionizing radiation are the chief challenges of radiotherapy that can lead to different adverse effects. It was shown that the combined treatment of radiotherapy and natural bioactive compounds (such as silymarin/silibinin) can alleviate the ionizing radiation-induced adverse side effects and induce synergies between these therapeutic modalities. In the present review, the potential radiosensitization effects of silymarin/silibinin during cancer radiation exposure/radiotherapy were studied.

METHODS

According to the PRISMA guideline, a systematic search was performed for the identification of relevant studies in different electronic databases of Google Scholar, PubMed, Web of Science, and Scopus up to October 2022. We screened 843 articles in accordance with a predefined set of inclusion and exclusion criteria. Seven studies were finally included in this systematic review.

RESULTS

Compared to the control group, the cell survival/proliferation of cancer cells treated with ionizing radiation was considerably less, and silymarin/silibinin administration synergistically increased ionizing radiation-induced cytotoxicity. Furthermore, there was a decrease in the tumor volume, weight, and growth of ionizing radiation-treated mice as compared to the untreated groups, and these diminutions were predominant in those treated with radiotherapy plus silymarin/ silibinin. Furthermore, the irradiation led to a set of biochemical and histopathological changes in tumoral cells/tissues, and the ionizing radiation-induced alterations were synergized following silymarin/silibinin administration (in most cases).

CONCLUSION

In most cases, silymarin/silibinin administration could sensitize the cancer cells to ionizing radiation through an increase of free radical formation, induction of DNA damage, increase of apoptosis, inhibition of angiogenesis and metastasis, etc. However, suggesting the use of silymarin/silibinin during radiotherapeutic treatment of cancer patients requires further clinical studies.

Ocular complications with the use of radium-223: a case series

Background

Radium-223 is used for the treatment of osseous metastases in castrate-resistant prostate cancer, and has been shown to increase time to the first skeletal-related event, reduce the rate of hospitalization, and improve quality of life. It is well tolerated, with hematologic toxicity as the main adverse event. Thus far, no ocular complication has been reported in the literature after initial administration of radium-223 with a single case reported of ocular complications after a patient’s second course of radium-223.

Case presentations

We present three cases of ocular complications after the use of radium-223 in patients with metastatic prostatic adenocarcinoma. Ocular complications presented as blurry vision, and formal diagnosis included uveitis and hyphema.

Conclusions

Documentation of adverse events is exceedingly important due to the high incidence of metastatic prostate cancer and increasing interest for the use of radium-223 in other osteoblastic disease. The authors postulate that these ocular complications may be a result of radiation’s potential effect on neovascularization, polypharmacy, or the biomolecular effects of radium-223 on integral signaling proteins, potentially coupled with poor underlying ocular health.

Key radioresistance regulation models and marker genes identified by integrated transcriptome analysis in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a malignancy that is endemic to China and Southeast Asia. Radiotherapy is the usual treatment, however, radioresistance remains a major reason for failure. This study aimed to find key radioresistance regulation models and marker genes of NPC and clarify the mechanism of NPC radioresistance by RNA sequencing and bioinformatics analysis of the differences in gene expression profiles between radioresistant and radiosensitive NPC tissues. A total of 21 NPC biopsy specimens with different radiosensitivity were analyzed by RNA sequencing. Differentially expressed genes in RNA sequencing data were identified using R software. The differentially expressed gene data derived from RNA sequencing as well as prior knowledge in the form of pathway databases were integrated to find sub‐networks of related genes. The data of RNA sequencing with the GSE48501 data from the GEO database were combined to further search for more reliable genes associated with radioresistance of NPC. Survival analyses using the Kaplan–Meier method based on the expression of the genes were conducted to facilitate the understanding of the clinical significance of the differentially expressed genes. RT‐qPCR was performed to validate the expression levels of the differentially expressed genes. We identified 1182 differentially expressed genes between radioresistant and radiosensitive NPC tissue samples. Compared to the radiosensitive group, 22 genes were significantly upregulated and 1160 genes were downregulated in the radioresistant group. In addition, 10 major NPC radiation resistance network models were identified through integration analysis with known NPC radiation resistance‐associated genes and mechanisms. Furthermore, we identified three core genes, DOCK4, MCM9, and POPDC3 among 12 common downregulated genes in the two datasets, which were validated by RT‐qPCR. The findings of this study provide new clues for clarifying the mechanism of NPC radioresistance, and further experimental studies of these core genes are warranted.

223-Radium for metastatic osteosarcoma: combination therapy with other agents and external beam radiotherapy

Background

Bone-seeking radiopharmaceuticals can deposit radiation selectively to some osteosarcoma tumours because of the bone-forming nature of this cancer.

Objectives

This is the first report of using 223-radium, an alpha-emitting calcium analogue with a high therapeutic index, in combination therapy with other agents in 15 patients with metastatic osteoblastic osteosarcoma.

Methods

Candidates for alpha-radiotherapy if ^99mTc-MDP bone scan had avid bone-forming lesions and no therapy of higher priority (eg, definitive surgery). Monthly 223-radium infusions (1.49 μCi/kg or 55.13 kBq/kg) were given.

Results

The median infusion number was three and the average time to progression was 4.3 months for this cohort receiving 223-radium+other agents. Agents provided during 223-radium included (1) drugs to reduce skeletal complications: monthly denosumab (n=13) or zolendronate (n=1); (2) agents with antivascular endothelial growth factor activity, pazopanib (n=8) or sorafenib (n=1), (3) alkylating agents: oral cyclophosphamide (n=1) or ifosfamide, given as a 14-day continuous infusion (n=1, two cycles), (4) high-dose methotrexate (n=1), pegylated liposomal doxorubicin (n=1); and (5) two other combinations: nivolumab and everolimus (n=1) and rapamycin and auranofin (n=1). Radiation therapy, including stereotactic body radiotherapy (SBRT), was also given to 11 patients concurrently with 223-radium (n=2), after 223-radium completion (n=3), or both concurrently and then sequentially for other sites (n=6). After 223-radium infusions, patients without RT had a median overall survival of 4.3 months compared with those with SBRT and/or RT, who had a median overall survival of 13.5 months.

Conclusion Although only 1/15 of patients with osteoblastic osteosarcoma still remain alive after 223-radium, overall survival

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.

Combining Radiotherapy With Anti-angiogenic Therapy and Immunotherapy; A Therapeutic Triad for Cancer?

Radiotherapy has been used for the treatment of cancer for over a century. Throughout this period, the therapeutic benefit of radiotherapy has continuously progressed due to technical developments and increased insight in the biological mechanisms underlying the cellular responses to irradiation. In order to further improve radiotherapy efficacy, there is a mounting interest in combining radiotherapy with other forms of therapy such as anti-angiogenic therapy or immunotherapy. These strategies provide different opportunities and challenges, especially with regard to dose scheduling and timing. Addressing these issues requires insight in the interaction between the different treatment modalities. In the current review, we describe the basic principles of the effects of radiotherapy on tumor vascularization and tumor immunity and vice versa. We discuss the main strategies to combine these treatment modalities and the hurdles that have to be overcome in order to maximize therapeutic effectivity. Finally, we evaluate the outstanding questions and present future prospects of a therapeutic triad for cancer.

Roles of miR-200 family members in lung cancer: more than tumor suppressors

miRNAs are a class of single-stranded noncoding RNAs, which have no coding potential, but modulate many molecular mechanisms including cancer pathogenesis. miRNAs participate in cell proliferation, differentiation, apoptosis, as well as carcinogenesis or cancer progression, and their involvement in lung cancer has been recently shown. They are suggested to have bidirectional functions on important cancer-related genes so as to enhance or attenuate tumor genesis. Epithelial-mesenchymal transition (EMT) is a fundamental process which contributes to integrity of organogenesis and tissue differentiation as well as tissue repair, organ fibrosis and the progression of carcinoma, and several miRNAs were suggested to form the network regulating EMT in lung cancer, among which, miR-200 family members (miR-200a, miR-200b, miR-200c, miR-429 and miR-141) play crucial roles in the suppression of EMT.

Toll-like receptor 4 and its associated proteins as prognostic factors for HCC treated by post-radiotherapy surgery

Locally advanced hepatocellular carcinoma (HCC) treated by radiotherapy (RT) may be suited for further treatment with surgery. As a critical mediator of the post-RT immune response, Toll-like receptor 4 (TLR4) and its associated proteins may serve as prognostic factors for patients with HCC treated by post-RT surgery. In the present study, a total of 20 patients with HCC treated by post-RT surgery were enrolled. Resected tumor and peritumoral liver tissues were used to construct tissue microarrays that were assessed with immunohistochemical staining for the expression levels of TLR4, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and vascular endothelial growth factor receptor 2 (VEGFR2). The overall (OS) and disease-free (DFS) survival outcomes for each patient were assessed, and the severity of radiation-induced liver diseases (RILDs) was detected. The patients with low TLR4 or TRAIL expression exhibited significantly better OS times than those with high TLR4 (P=0.003) or TRAIL (P=0.007) expression, whereas the median DFS times for patients with low VEGFR2 or TRAIL were significantly longer than those with high VEGFR2 (P=0.003) or TRAIL (P=0.008) expression. No significant differences in OS or DFS times were identified according to the expression of TLR4, VEGFR2 or TRAIL in peritumoral liver tissue, although more severe RILDs were identified in patients with the high expression of these factors in the peritumoral liver tissue post-RT (P<0.05). Therefore, the expression levels of TLR4 and its associated proteins in HCC tumors may be suitable as prognostic factors for patients with HCC treated by post-RT surgery. The inhibition of TLR4, VEGFR2 and TRAIL expression in HCC and non-tumor liver tissue may lessen the severity of RILDs and improve survival outcomes in the future.

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.

Radiation-Induced Enhancement of Antitumor T-cell Immunity by VEGF-Targeted 4-1BB Costimulation

Radiotherapy can elicit systemic immune control of local tumors and distant nonirradiated tumor lesions, known as the abscopal effect. Although this effect is enhanced using checkpoint blockade or costimulatory antibodies, objective responses remain suboptimal. As radiotherapy can induce secretion of VEGF and other stress products in the tumor microenvironment, we hypothesized that targeting immunomodulatory drugs to such products will not only reduce toxicity but also broaden the scope of tumor-targeted immunotherapy. Using an oligonucleotide aptamer platform, we show that radiation-induced VEGF-targeted 4-1BB costimulation potentiated both local tumor control and abscopal responses with equal or greater efficiency than 4-1BB, CTLA-4, or PD1 antibodies alone. Although 4-1BB and CTLA-4 antibodies elicited organ-wide inflammatory responses and tissue damage, VEGF-targeted 4-1BB costimulation produced no observable toxicity. These findings suggest that radiation-induced tumor-targeted immunotherapy can improve the therapeutic index and extend the reach of immunomodulatory agents. Cancer Res; 77(6); 1310-21. ©2017 AACR.

Interactions between osteopontin and vascular endothelial growth factor: Implications for cancer

For this comprehensive review, 257 publications with the keywords "osteopontin" or "OPN" and "vascular endothelial growth factor" or "VEGF" in PubMed were screened (time frame from year 1996 to year 2014). 37 articles were excluded because they were not focused on the interactions between these molecules, and papers relevant for transformation-related phenomena were selected. Osteopontin (OPN) and vascular endothelial growth factor (VEGF) are characterized by a convergence in function for regulating cell motility and angiogenesis, the response to hypoxia, and apoptosis. Often, they are co-expressed or one molecule induces the other, however, in some settings OPN-associated pathways and VEGF-associated pathways are distinct. Their relationships affect the pathogenesis in cancer, where they contribute to progression and angiogenesis and serve as markers for poor prognosis. The inhibition of OPN may reduce VEGF levels and suppress tumor progression. In vascular pathologies, these two cytokines mediate remodeling, but may also perpetuate inflammation and narrowing of the arteries. OPN and VEGF are elevated and contribute to vascularization in inflammatory diseases.

TLR4-dependent immune response promotes radiation-induced liver disease by changing the liver tissue interstitial microenvironment during liver cancer radiotherapy

Liver tissue interstitial fluid (TIF) a special microenvironment around liver cells, which may play a vital role in cell communication during liver injury. Moreover, toll-like receptor 4 (TLR4) is an important trigger of the immune response that may also play a role in liver injuries, including radiation-induced liver disease (RILD). Therefore, the purpose of this study was to identify the roles of the TLR4-dependent immune response and TIFs in RILD after radiation therapy (RT) for liver cancer. This study consisted of two phases, and in the primary phase, the livers of TLR4 mutant (TLR4(-)) and normal (TLR4(+)) mice were irradiated with 30 Gy. TIF was then obtained from mouse livers and assessed by cytokine array analysis 20 days after irradiation, and cytokines in the TIFs, TLR4 and RILD were analyzed. In the second or validation phase, hepatocytes were isolated from TLR4(+) or TLR4(-) mice irradiated with 8 Gy and were co-cultured with TIFs from mouse livers, apoptosis of the hepatocytes was then measured using flow cytometry. We found that severe RILD was accompanied by higher expression of granulocyte macrophage colony-stimulating factor (GM-CSF), tumor necrosis factor-related apoptosis inducing ligand (TRAIL) and vascular endothelial growth factor receptor 2(VEGFR-2) in liver TIFs, from in TLR4(+) mice compared with TLR4(-) mice (P < 0.05). In both TLR4(+) and TLR4(-) hepatocytes, apoptosis after irradiaton was increased significantly after co-culture in TIFs from TLR4(+) mice that had their livers irradiated, compared with TIFs from TLR4(-) mice that had their livers irradiated or TIFs from unirradiated mice (P < 0.05). In summary, these findings indicate that the TLR4-dependent immune response may promote RILD by enhancing the expression of GM-CSF, VEGFR-2 and TRAIL in liver TIFs.

HAb18G/CD147 promotes radioresistance in hepatocellular carcinoma cells: a potential role for integrin β1 signaling

Radiotherapy has played a limited role in the treatment of hepatocellular carcinoma (HCC) due to the risk of tumor radioresistance. A previous study in our laboratory confirmed that CD147 interacts with integrin β1 and plays an important role in modulating the malignant properties of HCC cells. In this study, we further evaluated the role of CD147 in the radioresistance of HCC and as a potential target for improving radiosensitivity. Upon irradiation, the colony formation, apoptosis, cell-cycle distribution, migration, and invasion of SMMC-7721, CD147-knockout SMMC-7721, HepG2, and CD147-knockdown HepG2 cells were determined. A nude mouse xenograft model and a metastatic model of HCC were used to detect the role of CD147 in radioresistance in vivo. Deletion of HAb18G/CD147 significantly enhanced the radiosensitivity of SMMC-7721 and HepG2 cells, and knocking out HAb18G/CD147 in SMMC-7721 cells attenuated irradiation-enhanced migration and invasion. The knockout and antibody blockade of CD147 decreased the tumor growth and metastatic potentials of HCC cells under irradiation. CD147-deleted SMMC-7721 cells showed diminished levels of calpain, cleaved talin, active integrin β1, and decreased p-FAK (Tyr397) and p-Akt (Ser473) levels. FAK and PI3K inhibitors, as well as integrin β1 antibodies, increased the radiation-induced apoptosis of SMMC-7721 cells. Our data provide evidence for CD147 as an important determinant of radioresistance via the regulation of integrin β1 signaling. Inhibition of the HAb18G/CD147 integrin interaction may improve the efficiency of radiosensitivity and provide a potential new approach for HCC therapy.

Aberrant expression of osteopontin and E-cadherin indicates radiation resistance and poor prognosis for patients with cervical carcinoma

Radiotherapy is the first-line treatment for all stages of cervical cancer, whether it is used for radical or palliative therapy. However, radioresistance of cervical cancer remains a major therapeutic problem. Consequently, we explored if E-cadherin (a marker of epithelial-mesenchymal transition) and osteopontin could predict radioresistance in patients with locally advanced cervical squamous cell carcinoma (LACSCC). Patients were retrospectively reviewed and 111 patients divided into two groups (radiation-resistant and radiation-sensitive groups) according to progression-free survival (PFS). In pretreated paraffin-embedded tissues, we evaluated E-cadherin and osteopontin expression using immunohistochemical staining. The percentage of patients with high osteopontin but low E-cadherin expression in the radiation-resistant group was significantly higher than those in the radiation-sensitive group (p<0.001). These patients also had a lower 5-year PFS rate (p<0.001). Our research suggests that high osteopontin but low E-cadherin expression can be considered as a negative, independent prognostic factor in patients with LACSCC ([Hazard ratios (95% CI) 6.766 (2.940, 15.572)], p<0.001).

Ginsenoside Rg3 enhances radiosensitization of hypoxic oesophageal cancer cell lines through vascular endothelial growth factor and hypoxia inducible factor 1α

Objective

To determine if the pretreatment of hypoxic human oesophageal carcinoma cell lines (EC109, TE1 and KYSE170) with ginsenoside Rg3 (Rg3) increases their radiosensitivity to X-rays.

Methods

The growth inhibitory effect of different Rg3 concentrations was measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) assay. Radiation sensitivity was measured using a clone formation assay and flow cytometry was used to measure the effects of Rg3 on radiation-induced apoptosis. Western blot analysis was used to measure the effects of Rg3 on the levels of hypoxia inducible factor (HIF)-1α and vascular endothelial growth factor (VEGF).

Results

Rg3 inhibited EC109, TE1 and KYSE170 cell growth in a dose- and time-dependent manner. Pretreatment with 10 µmol/ml Rg3 increased EC109, TE1 and KYSE170 radiosensitivity. Rg3 plus radiation significantly increased the apoptosis rate compared with radiation alone. Rg3 also decreased VEGF and HIF-1α protein levels in EC109 cells in a dose-dependent manner. The combination of Rg3 and radiation increased the fragmentation of double-stranded DNA.

Conclusion

Rg3 enhanced the radiosensitivity of human oesophageal carcinoma cell lines cultured under hypoxic conditions possibly by downregulating VEGF and HIF-1α protein levels.

A pilot study on potential plasma hypoxia markers in the radiotherapy of non-small cell lung cancer. Osteopontin, carbonic anhydrase IX and vascular endothelial growth factor

BACKGROUND

Hypoxic radioresistance plays a critical role in the radiotherapy of cancer and adversely impacts prognosis and treatment response. This prospective study investigated the interrelationship and the prognostic significance of several hypoxia-related proteins in non-small cell lung cancer (NSCLC) patients treated by radiotherapy ± chemotherapy.

MATERIAL AND METHODS

Pretreatment osteopontin (OPN), vascular endothelial growth factor (VEGF) and carbonic anhydrase IX (CA IX) plasma levels were determined by ELISA in 55 NSCLC (M0) patients receiving 66 Gy curative-intent radiotherapy or chemoradiation. Marker correlation, association with clinicopathological parameters and the prognostic value of a biomarker combination was evaluated.

RESULTS

All biomarkers were linearly correlated and linked to different clinical parameters including lung function, weight loss (OPN), gross tumor volume (VEGF) and T stage (CA IX). High OPN (p = 0.03), VEGF (p = 0.02) and CA IX (p = 0.04) values were significantly associated with poor survival. Double marker combination additively increased the risk of death by a factor of 2 and high plasma levels of the triple combination OPN/VEGF/CA IX yielded a 5.9-fold risk of death (p = 0.009). The combined assessment of OPN/VEGF/CA IX correlated independently with prognosis (p = 0.03) in a multivariate Cox regression model including N stage, T stage and GTV.

CONCLUSION

This pilot study suggests that a co-detection augments the prognostic value of single markers and that the integration of OPN, VEGF and CA IX into a hypoxic biomarker profile for the identification of patients with largely hypoxic and radioresistant tumors should be further evaluated.

MiR-200c increases the radiosensitivity of non-small-cell lung cancer cell line A549 by targeting VEGF-VEGFR2 pathway

MicroRNAs (miRNAs) have been demonstrated to participate in many important cellular processes including radiosensitization. VEGF family, an important regulator of angiogenesis, also plays a crucial role in the regulation of cancer cell radiosensitivity. VEGFR2 mediates the major growth and permeability actions of VEGF in a paracrine/autocrine manner. MiR-200c, at the nexus of epithelial-mesenchymal transition (EMT), is predicted to target VEGFR2. The purpose of this study is to test the hypothesis that regulation of VEGFR2 pathway by miR-200c could modulate the radiosensitivity of cancer cells. Bioinformatic analysis, luciferase reporter assays and biochemical assays were carried out to validate VEGFR2 as a direct target of miR-200c. The radiosensitizing effects of miR-200c on A549 cells were determined by clonogenic assays. The downstream regulating mechanism of miR-200c was explored with western blotting assays, FCM, tube formation assays and migration assays. We identified VEGFR2 as a novel target of miR-200c. The ectopic miR-200c increased the radiosensitivity of A549 while miR-200c down-regulation decreased it. Besides, we proved that miR-200c radiosensitized A549 cells by targeting VEGF-VEGFR2 pathway specifically, thus leading to inhibition of its downstream pro-survival signaling transduction and angiogenesis, and serves as a potential target for radiosensitizition research.

Studies on the role of osteopontin-1 in endometrial cancer cell lines

BACKGROUND

Osteopontin-1 is a well characterized protein in many tumour entities. Multiple roles in the processes invasion, metastasis and angiogenesis of tumours are attributed to osteopontin-1. The putative role of osteopontin-1 has not been characterized for endometrial cancer.

MATERIAL AND METHODS

We investigated multiple endometrial cancer cell lines for osteopontin-1 mRNA- and protein-expression. Osteopontin-1 dependent effects were analysed in vitro by siRNA inhibition.

RESULTS

All endometrial cell lines expressed osteopontin-1. Expression of osteopontin-1 was successfully inhibited by specific siRNA. Cells with reduced osteopontin-1 expression showed decreased migration in the Boyden chamber assay and invasion was reduced in the wound-healing assay. Osteopontin-1 seems to play a role in apoptotic processes of endometrial cancer cells. Inhibition of osteopontin-1 expression was associated with an increased susceptibility for radiation therapy.

CONCLUSION

Osteopontin-1 seems to play a role in endometrial cancer. Inhibition of osteopontin-1 expression leads to a higher susceptibility for radiation therapy. Our results suggest that a reduced expression of osteopontin-1 in endometrial cancer could inhibit the development of invasion and metastasis in these cells.

Regulatory mechanisms and clinical perspectives of miRNA in tumor radiosensitivity

MicroRNA (miRNA) influences carcinogenesis at multiple stages and it can effectively control tumor radiosensitivity by affecting DNA damage repair, cell cycle checkpoint, apoptosis, radio-related signal transduction pathways and tumor microenvironment. MiRNA also efficiently modulates tumor radiosensitivity at multiple levels by blocking the two essential non-homologous end-joining repair and homologous recombination repair pathways in the DNA damage response. It interferes with four radio-related pathways in ionizing radiation, including the PI3-K/Akt, NF-κB, MAPK and TGFβ signaling pathways. Moreover, the regulatory effect of miRNA in radiosensitivity can be enhanced when interacting with various key molecules, including H2AX, BRCA1, ATM, DNA-PK, RAD51, Chk1, Cdc25A, p53, PLK1, HIF-1 and VEGF, which are involved in these processes. Therefore, thoroughly understanding the mechanism of miRNA in tumor radiosensitivity could assist in finding novel targets to improve the radiotherapeutic effects and provide new clinical perspectives and insights for developing effective cancer treatments.

Opportunities and challenges facing biomarker development for personalized head and neck cancer treatment

Head and neck oncologists have traditionally relied on clinical tumor features and patient characteristics to guide care of individual patients. As surgical, radiotherapeutic, and systemic treatments have evolved to become more anatomically precise and mechanistically specific, the opportunity for improved cure and functional patient recovery has never been more promising for this historically debilitating cancer. However, personalized treatment must be accompanied by sophisticated patient selection to triage the application of advanced therapies toward ideal patient candidates. In this monograph, we review current progress, investigative themes, and key challenges facing head and neck cancer biomarker development intended to make personalized head and neck cancer treatment a clinical reality.

The enhancement of radiosensitivity in human esophageal carcinoma cells by thalidomide and its potential mechanism

To investigate the effects of thalidomide on the radiosensitivity of human esophageal cancer cells (TE1 cells) and the potential mechanism underlying these effects. The effects of thalidomide on proliferation of TE1 cells were determined by Methyl thiazolyl tetrazolium assay. The multitarget click model was used to delineate the survival curve using a colony-forming assay, and the radiosensitivity was determined after TE1 cells were treated by thalidomide and/or X-ray radiation. The cell cycle was detected using flow cytometry. Our results are as follows: thalidomide alone suppressed the proliferation of TE1 cells in a dose- and time-dependent manner. The suppressive effects were enhanced by prolonged duration or elevated concentration of thalidomide. However, thalidomide did not affect the cell cycle of TE1 cells. The expression of vascular endothelial growth factor (VEGF) mRNA and protein was suppressed after treatment with thalidomide alone in a dose-dependent manner. Synergistic suppressive effects on VEGF expression were observed after administration of thalidomide and X-ray exposure. In conclusion, thalidomide was able to enhance the radiosensitivity of TE1 cells in vitro, which could be closely related to its suppressive effects on the expression of VEGF in TE1 cells, but had no obvious effects on the cell cycle.

Genetic variations in VEGF and VEGFR2 and glioblastoma outcome

Vascular endothelial growth factor (VEGF) and its receptors (VEGFR) are central components in the development and progression of glioblastoma. To investigate if genetic variation in VEGF and VEGFR2 is associated with glioblastoma prognosis, we examined blood samples from 154 glioblastoma cases collected in Sweden and Denmark between 2000 and 2004. Seventeen tagging single nucleotide polymorphisms (SNPs) in VEGF and 27 in VEGFR2 were genotyped and analysed, covering 90% of the genetic variability within the genes. In VEGF, we found no SNPs associated with survival. In VEGFR2, we found two SNPs significantly associated to survival, namely rs2071559 and rs12502008. However, these results are likely to be false positives due to multiple testing and could not be confirmed in a separate dataset. Overall, this study provides little evidence that VEGF and VEGFR2 polymorphisms are important for glioblastoma survival.

Effects of osteopontin inhibition on radiosensitivity of MDA-MB-231 breast cancer cells

Background

Osteopontin (OPN) is a secreted glycophosphoprotein that is overexpressed in various tumors, and high levels of OPN have been associated with poor prognosis of cancer patients. In patients with head and neck cancer, high OPN plasma levels have been associated with poor prognosis following radiotherapy. Since little is known about the relationship between OPN expression and radiosensitivity, we investigated the cellular and radiation induced effects of OPN siRNA in human MDA-MB-231 breast cancer cells.

Methods

MDA-MB-231 cells were transfected with OPN-specific siRNAs and irradiated after 24 h. To verify the OPN knockdown, we measured the OPN mRNA and protein levels using qRT-PCR and Western blot analysis. Furthermore, the functional effects of OPN siRNAs were studied by assays to assess clonogenic survival, migration and induction of apoptosis.

Results

Treatment of MDA-MB-231 cells with OPN siRNAs resulted in an 80% decrease in the OPN mRNA level and in a decrease in extracellular OPN protein level. Transfection reduced clonogenic survival to 42% (p = 0.008), decreased the migration rate to 60% (p = 0.15) and increased apoptosis from 0.3% to 1.7% (p = 0.04). Combination of OPN siRNA and irradiation at 2 Gy resulted in a further reduction of clonogenic survival to 27% (p < 0.001), decreased the migration rate to 40% (p = 0.03) and increased apoptosis to 4% (p < 0.005). Furthermore, OPN knockdown caused a weak radiosensitization with an enhancement factor of 1.5 at 6 Gy (p = 0.09) and a dose modifying factor (DMF₁₀) of 1.1.

Conclusion

Our results suggest that an OPN knockdown improves radiobiological effects in MDA-MB-231 cells. Therefore, OPN seems to be an attractive target to improve the effectiveness of radiotherapy.

High dose-per-fraction irradiation of limited lung volumes using an image-guided, highly focused irradiator: simulating stereotactic body radiotherapy regimens in a small-animal model

PURPOSE

To investigate the underlying biology associated with stereotactic body radiotherapy (SBRT), both in vivo models and image-guided, highly focal irradiation systems are necessary. Here, we describe such an irradiation system and use it to examine normal tissue toxicity in a small-animal model at lung volumes similar to those associated with human therapy.

METHODS AND MATERIALS

High-dose radiation was delivered to a small volume of the left lung of C3H/HeJCr mice using a small-animal stereotactic irradiator. The irradiator has a collimation mechanism to produce focal radiation beams, an imaging subsystem consisting of a fluorescent screen coupled to a charge-coupled device camera, and a manual positioning stage. Histopathologic examination and micro-CT were used to evaluate the radiation response.

RESULTS

Focal obliteration of the alveoli by fibrous connective tissue, hyperplasia of the bronchiolar epithelium, and presence of a small number of inflammatory cells are the main reactions to low-volume/high-dose irradiation of the mouse lung. The tissue response suggested a radiation dose threshold for early phase fibrosis lying between 40 and 100 Gy. The irradiation system satisfied our requirements of high-dose-rate, small beam diameter, and precise localization and verification.

CONCLUSIONS

We have established an experimental model and image-guided animal irradiation system for the study of high dose per fraction irradiations such as those used with SBRT at volumes analogous to those used in human beings. It will also allow the targeting of specific anatomical structures of the thorax or ultimately, orthotopic tumors of the lung.

Effects of irradiation on tumor cell survival, invasion and angiogenesis

Ionizing irradiation is a widely applied therapeutic method for the majority of solid malignant neoplasms, including brain tumors where, depending on localization, this might often be the only feasible primary intervention.Without doubt, it has been proved to be a fundamental tool available in the battlefield against cancer, offering a clear survival benefit in most cases. However, numerous studies have associated tumor irradiation with enhanced aggressive phenotype of the remaining cancer cells. A cell population manages to survive after the exposure, either because it receives sublethal doses and/or because it successfully utilizes the repair mechanisms. The biology of irradiated cells is altered leading to up-regulation of genes that favor cell survival, invasion and angiogenesis. In addition, hypoxia within the tumor mass limits the cytotoxicity of irradiation, whereas irradiation itself may worsen hypoxic conditions, which also contribute to the generation of resistant cells. Activation of cell surface receptors, such as the epidermal growth factor receptor, utilization of signaling pathways, and over-expression of cytokines, proteases and growth factors, for example the matrix metalloproteinases and vascular endothelial growth factor, protect tumor and non-tumor cells from apoptosis, increase their ability to invade to adjacent or distant areas, and trigger angiogenesis. This review will try to unfold the various molecular events and interactions that control tumor cell survival, invasion and angiogenesis and which are elicited or influenced by irradiation of the tumor mass, and to emphasize the importance of combining irradiation therapy with molecular targeting.

Sublethal total body irradiation leads to early cerebellar damage and oxidative stress

The present study aimed at identifying early damage index in the cerebellum following total body irradiation (TBI). Adult male CD2F1 mice (n=18) with or without TBI challenge (8.5 Gy irradiation) were assessed for histology and expression of selected immunohistochemical markers including malondiadehyde (MDA), 8-hydroxy-2'-deoxyguanosine (8-OHdG), protein 53 (p53), vascular endothelial growth factor receptor 2 (VEGF-R2), CD45, calbindin D-28k (CB- 28) and vesicular glutamate transport-2 (VGLUT2) in cerebellar folia II to IV. Compared to sham-controls, TBI significantly increased vacuolization of the molecular layer. At high magnification, deformed fiber-like structures were found along with the empty matrix space. Necrotic Purkinje cells were identified on 3.5 days after TBI, but not on 1 day. Purkinje cell count was reduced significantly 3.5 days after TBI. Compared with sham control, overall intensities of MDA and 8-OHdG immunoreactivities were increased dramatically on 1 and 3.5 days after TBI. Expression of VEGF-R2 was identified to be co-localized with 8-OHdG after TBI. This validates microvessel endothelial damage. The p53 immunoreactivities mainly deposited in the granular layer and microvessels after TBI and co-localization of the p53 with the CD45, both which were found within the microvessels. After TBI, CB28 expression decreased whereas the VGLUT2 expression increased significantly; Purkinje cells exhibited a reduced body size and deformity of dendritic arbor, delineated by CB28 immunoreactivity. Substantial damage to the cerebellum can be detectable as early as 1- 3.5 days in adult animals following sublethal TBI. Oxidative stress, inflammatory response and calcium neurotoxicity-associated mechanisms are involved in radiation-induced neuronal damage.