Radiation‐induced sarcoma in patients with nasopharyngeal carcinoma

BACKGROUND:

The increasing incidence of radiation‐induced sarcoma (RIS) has become a significant problem that can limit long‐term survival. The objective of the current study was to analyze the clinicopathologic characteristics, treatment outcomes, and prognostic factors of RIS after radiotherapy for nasopharyngeal carcinoma (NPC).

METHODS:

Institutional electronic medical records of patients with NPC who received definitive radiotherapy between February 1964 and 2003 were reviewed. Fifty‐three patients who developed RIS and fulfilled the study criteria were included.

RESULTS:

The median follow‐up after a diagnosis of RIS was 15.5 months (range, 0.4‐90.3 months), and the median latency between radiotherapy for NPC and an RIS diagnosis was 9.3 years (range, 3.2‐26.6 years). Fibrosarcoma was the most frequent histologic type observed, followed by osteosarcoma, and malignant fibrous histiocytoma. The 3‐year overall survival (OS) rate for 49 patients who received treatment was 32.4%, and the median survival was 21.2 months (95% confidence interval, 8.7‐33.8 months). The median OS was 41.3 months, 8.4 months, and 11 months for the complete resection group, the incomplete resection group, and the chemotherapy group, respectively (P<.0001). The only independent predictive factor that was associated with better OS was complete surgical resection.

CONCLUSIONS:

This retrospective study confirmed the rarity and poor prognosis of RIS in patients with NPC. Complete surgical resection was a significant prognostic factor for survival. The authors concluded that long‐term follow‐up is necessary for the early detection of RIS in patients with NPC. Cancer 2010. © 2010 American Cancer Society.     

Role of autophagy in high linear energy transfer radiation‐induced cytotoxicity to tumor cells

Heavy‐ion radiotherapy has a potential advantage over conventional radiotherapy due to improved dose distribution and a higher biological effectiveness in cancer therapy. However, there is a little information currently available on the cellular and molecular basis for heavy‐ion irradiation‐induced cell death. Autophagy, as a novel important target to improve anticancer therapy, has recently attracted considerable attention. In this study, the effect of autophagy induced by high linear energy transfer (LET) carbon ions was examined in various tumor cell lines. To our knowledge, our study is the first to reveal that high‐LET carbon ions could induce autophagy in various tumor cells effectively, and the autophagic level in the irradiated cells increased in a dose‐ and LET‐dependent manner. The ability of carbon ions to inhibit the activation of the PI3K/Akt pathway rose with increasing their LET. Moreover, modulation of autophagy in tumor cells could modify their sensitivity to high‐LET radiation, and inhibiting autophagy accelerated apoptotic cell death, resulting in an increase in radiosensitivity. Our data imply that targeting autophagy might enhance the effectiveness of heavy‐ion radiotherapy.     

Capn4 is induced by and required for Epstein‐Barr virus latent membrane protein 1 promotion of nasopharyngeal carcinoma metastasis through ERK/AP‐1 signaling

Capn4, also known as CapnS1, is a member of the calpain family, which plays a crucial role in maintaining the activity and function of calpain. We previously reported that Capn4 also plays an essential role in the migration of nasopharyngeal carcinoma (NPC) cells through regulation of (MMP‐2) by nuclear factor‐kappa B activation. Epstein‐Barr virus latent membrane protein 1 (LMP1) is closely related to the malignant functions of NPC; however, the relationship between LMP1 and Capn4 in NPC remain unclear. Immunohistochemical studies showed that the level of LMP1 and Capn4 expression was high in both primary and metastatic NPC tissues, with a significantly positive correlation. We further found that LMP1 was able to upregulate the Capn4 promoter in a dose‐dependent way through the C‐terminal activation region (CTAR)1 and CTAR2 domains to activate AP‐1. Moreover, we also found that LMP1 activated AP‐1 through ERK/JNK phosphorylation. These findings indicate that Capn4 coordination with LMP1 promotes actin rearrangement and, ultimately, cellular migration. These results show that Capn4 coordination with LMP1 enhances NPC migration by increasing actin rearrangement involving ERK/JNK/AP‐1 signaling. Therapeutically, additional and more specific LMP1 and Capn4 targeted inhibitors could be exploited to treat NPC.     

Feasibility of using interpolated contours of targets and organs at risk in intensity‐modulated radiation therapy treatment planning for advanced‐stage nasopharyngeal carcinoma

To assess the dosimetric effect of using interpolated contours in planning intensity‐modulated radiation therapy (IMRT) for advanced T‐stage nasopharyngeal carcinoma. The present study focused on T3–T4 tumours where the proximity of targets to neurological organs poses a stringent test on the feasibility of such an approach. Contours of targets and organs were delineated on CT images of 2.5‐mm interval and a reference IMRT plan was generated. An investigative (INV) IMRT plan was then generated with the same planning protocol, but based on interpolated contours that replaced deleted contours on alternate slices. The reference and INV plans were compared. Regarding target coverage, all targets in the INV plans met the acceptance criteria except for the PTV in one case. Regarding organs, the mean dose to 1% volume of the brainstem and spinal cord in the INV plans were kept below their dose limits. No significant differences in the mean doses to others organs were found. Satisfactory target coverage and protection of critical organs to a degree similar to full‐scale contouring could be achieved with use of interpolated contours. The saving in manpower time for contouring is expected to significantly improve the throughput of the IMRT planning process.     

Role of p115RhoGEF in the regulation of extracellular Ca2+‐induced choline kinase activation and prostate cancer cell proliferation

Ca²⁺ is a ubiquitous cellular signal which plays a central role in the regulation of cell function. To understand aberrant signaling through the Ca²⁺‐sensing receptor (CaR) in prostate cancer cells, we compared expression of CaR signaling components in human nonmalignant prostate epithelial cells and several prostate cancer cell lines, as well as normal human prostate and prostate tumor specimens. We found that levels of the CaR, Gα₁₂ and p115RhoGEF expression are significantly up‐regulated in more tumorigenic prostate cancer cells and prostate tumor specimens. By silencing CaR, Gα₁₂, p115RhoGEF or choline kinase (ChoK) expression, analyzing the change in lipid profiles, blocking signaling pathways using chemical inhibitors, and co‐immunoprecipitating the relevant signaling proteins, we demonstrate that p115RhoGEF, a regulator of G protein signaling (RGS) with GAP activity for Gα_12/13 and with guanine nucleotide exchange activity for the small G protein Rho, plays an important role in the regulation of Ca‐induced ChoK activation and cell proliferation in more tumorigenic prostate cancer cell lines. The results demonstrate an important role of p115RhoGEF in prostate tumorigenesis and provide a potential target of cancer therapeutics.     

Gabapentin for the treatment of pain syndrome related to radiation‐induced mucositis in patients with head and neck cancer treated with concurrent chemoradiotherapy

BACKGROUND:

This retrospective study evaluated the efficacy of gabapentin for the treatment of pain syndromes related to radiation‐induced mucositis in patients with head and neck cancers treated with concurrent chemoradiation.

METHODS:

Data from 42 patients with head and neck malignancies treated with concurrent chemoradiotherapy using an intensity‐modulated radiotherapy technique were analyzed. Gabapentin was initiated in the second week of radiotherapy. Opiates were prescribed in addition to gabapentin as clinically indicated to obtain adequate pain control.

RESULTS:

At a median dose of 2700 mg/day of gabapentin, only 33% and 55% of patients required additional low‐dose narcotic medications for pain control during the third and fourth week of treatment, respectively, despite exhibiting a grade 2 or higher mucositis in 71% and 86% of the patients, respectively. Furthermore, during the last weeks of treatment, 71% of the patients required additional low‐dose opiates for adequate pain control, despite the presence of grade 2 or higher mucositis in 95% and 100% of patients at Weeks 5 and 6, respectively. Only 1 patient had a treatment‐related interruption of >3 days during chemoradiotherapy.

CONCLUSIONS:

Gabapentin appears to be promising in reducing the need for high total doses of opioids and avoiding unplanned treatment interruptions for patients with head and neck malignancies treated with concurrent chemoradiotherapy and should be further evaluated prospectively in controlled clinical trials. Cancer 2010. © 2010 American Cancer Society.     

Upregulation of caveolin‐1 and CD147 expression in nasopharyngeal carcinoma enhanced tumor cell migration and correlated with poor prognosis of the patients

Expression of caveolin‐1 (Cav‐1) and extracellular matrix metalloproteinase inducer (EMMPRIN/CD147) and their prognostic significance were analyzed in archive NPC samples. Cav‐1 and CD147 were overexpressed in 49.48% (96/194) and 59.39% (117/197) of NPC, respectively. Both Cav‐1 and CD147 expression levels correlated significantly with metastasis (p = 0.025 and 0.017, respectively) and a lower 5‐year survival rate (p = 0.02 and 0.0009, respectively). In addition, Cav‐1 expression levels correlated significantly with local recurrence (p = 0.038). Multivariate Cox regression analysis indicated that combination of high Cav‐1 and CD147 expression was a significant, independent prognosis predictor in patients with NPC (HR = 2.135; p = 0.006). Functional studies revealed that overexpression of Cav‐1 promoted secretion of MMP‐3 and MMP‐11 (active) proteins, as well as an increase in the migratory ability of CNE1 and CNE2 cells, while siRNA‐mediated silencing of Cav‐1 or CD147 led to reduced levels of MMP‐3 and MMP‐11(active) secretion, and reduced migration capacity of CNE1 and CNE2 cells. We observed a positive correlation between Cav‐1 and CD147 expression in NPC (ρ = 0.330, p = 0.000), CD147 protein levels were upregulated in Cav‐1 overexpressing CNE1 and CNE2 cells, whereas siRNA‐mediated silencing of Cav‐1 led to the downregulation of CD147 expression. Our results indicate that Cav‐1 and CD147 overexpression predict poor NPC prognosis and enhanced tumor cell migration, which is associated with MMP‐3 and MMP‐11 (active) secretion. © 2009 UICC     

Blockade of MEK signaling potentiates 5‐Aza‐2′‐deoxycytidine‐induced apoptosis and upregulation of p21waf1 in acute myelogenous leukemia cells

We have recently reported that the mitogen‐activated protein kinase/ERK kinase (MEK) inhibitor AZD6244 (ARRY‐142886) strikingly potentiated the effects of histone deacetylase inhibitor to induce growth arrest and apoptosis of acute myelogeneous leukemia (AML) cells in association with enhanced upregulation of p21^waf1. This study examined the effects of the MEK inhibitor on the action of DNA methyltransferase inhibitor 5‐Aza‐2′‐deoxycytidine (5‐AzadC), another epigenetic agent in AML cells. AZD6244 significantly potentiated the ability of 5‐AzadC to induce growth arrest and apoptosis of NB4, and freshly isolated AML cells. In parallel, 5‐AzadC induced expression of p21^waf1 in AML cells, which was potently enhanced in the presence of AZD6244. Further studies explored the molecular mechanisms by which 5‐AzadC induced expression of p21^waf1 and found that a low dose of 5‐AzadC (1 μM) induced acetylation of histone H3 on the p21^waf1 gene promoter; however, higher dose of this compound (3 or 5 μM) potently induced DNA damage as assessed by expression of γH2AX, in NB4 cells. These effects were strikingly enhanced by concomitant blockade of MEK signaling. Furthermore, knock‐down of p21^waf1 by the siRNA rescued NB4 cells from 5‐AzadC‐mediated growth inhibition. Taken together, combination of 5‐AzadC and the MEK inhibitor may be useful for treatment of individuals with a subset of AML. © 2009 UICC     

Time‐dependent changes in proliferation,DNA damage and clock gene expression in hepatocellular carcinoma and healthy liver of a transgenic mouse model

Hepatocellular carcinoma (HCC) is highly resistant to anticancer therapy and novel therapeutic strategies are needed. Chronotherapy may become a promising approach because it may improve the efficacy of antimitotic radiation and chemotherapy by considering timing of treatment. To date little is known about time‐of‐day dependent changes of proliferation and DNA damage in HCC. Using transgenic c‐myc/transforming growth factor (TGFα) mice as HCC animal model, we immunohistochemically demonstrated Ki67 as marker for proliferation and γ‐H2AX as marker for DNA damage in HCC and surrounding healthy liver (HL). Core clock genes (Per1, Per2, Cry1, Cry2, Bmal 1, Rev‐erbα and Clock) were examined by qPCR. Data were obtained from samples collected ex vivo at four different time points and from organotypic slice cultures (OSC). Significant differences were found between HCC and HL. In HCC, the number of Ki67 immunoreactive cells showed two peaks (ex vivo: ZT06 middle of day and ZT18 middle of night; OSC: CT04 and CT16). In ex vivo samples, the number of γ‐H2AX positive cells in HCC peaked at ZT18 (middle of the night), while in OSC their number remained high during subjective day and night. In both HCC and HL, clock gene expression showed a time‐of‐day dependent expression ex vivo but no changes in OSC. The expression of Per2 and Cry1 was significantly lower in HCC than in HL. Our data support the concept of chronotherapy of HCC. OSC may become useful to test novel cancer therapies.     

Programmed death‐ligand 1 is prognostic factor in esophageal squamous cell carcinoma and is associated with epidermal growth factor receptor

Programmed death‐ligand 1 (PD‐L1) expression either indicates immune inhibitory status or concurrent immune response. Although the relationship between PD‐L1 and clinical outcomes has been studied widely in recent years, its role in prognosis of esophageal squamous cell carcinoma (ESCC) remains unclear. Here, we assessed the significance of PD‐L1 in ESCC and its association with epidermal growth factor receptor (EGFR) and radiation response. We found that PD‐L1 was present both on the surface of tumor cells and tumor‐infiltrating immune cells. Patients with tumor‐infiltrating immune cell PD‐L1 expression had better survival. PD‐L1 expression on immune cells was an independent prognostic factor for patients with ESCC. PD‐L1 expression either on tumor‐infiltrating immune cells or tumor cells was negatively associated with EGFR expression. EGFR/PD‐L1 pairs could separate the survival between EGFR low/PD‐L1 positive and EGFR high/PD‐L1 negative groups. In ESCC cell lines with EGFR high expression, PD‐L1 expression was induced significantly when EGFR signaling was activated by radiation and was dramatically inhibited by an EGFR tyrosine kinase inhibitor. In conclusion, tumor‐infiltrating immune cell PD‐L1 expression is an independent prognostic factor for ESCC, and the association between EGFR and PD‐L1 is vital to determining survival. It is important to consider radiotherapy‐induced imbalance of pro‐tumor and anti‐tumor immune response. A combination of radiotherapy and PD‐L1‐targeted therapy could be a promising therapeutic strategy for ESCC patients.     

MicroRNA‐196a promotes an oncogenic effect in head and neck cancer cells by suppressing annexin A1 and enhancing radioresistance

Radiotherapy is a major treatment modality for head and neck squamous cell carcinoma (HNSCC). Up to 50% of patients with locally advanced disease relapse after radical treatment and there is therefore a need to develop predictive bomarkers for clinical use that allow the selection of patients who are likely to respond. MicroRNA (miRNA) expression profiling of a panel of HNSCC tumours with and without recurrent disease after surgery and radiotherapy detected miR‐196a as one of the highest upregulated miRNAs in the poor prognostic group. To further study the role of miR‐196a, its expression was determined in eight head and neck cancer cell lines. Overexpression of miR‐196a in HNSCC cells, with low endogenous miR‐196a expression, significantly increased cell proliferation, migration and invasion, and induced epithelial to mesenchymal transition. Conversely, miR‐196a knockdown in cells with high endogenous expression levels significantly reduced oncogenic behaviour. Importantly, overexpression of miR‐196a increased radioresistance of cells as measured by gamma H2AX staining and MTT survival assay. Annexin A1 (ANXA1), a known target of miR‐196a, was found to be directly modulated by miR‐196a as measured by luciferase assay and confirmed by Western blot analysis. ANXA1 knockdown in HNSCC exhibited similar phenotypic effects to miR‐196a overexpression, suggesting the oncogenic effect of miR‐196a may at least be partly regulated through suppression of ANXA1. In conclusion, this study identifies miR‐196a as a potential important biomarker of prognosis and response of HNSCC to radiotherapy. Furthermore, our data suggest that miR‐196a and/or its target gene ANXA1 could represent important therapeutic targets in HNSCC.