Cancer prevention by adult‐onset calorie restriction after infant exposure to ionizing radiation in B6C3F1 male mice

Children are especially sensitive to ionizing radiation and chemical carcinogens, and limiting their cancer risk is of great public concern. Calorie restriction (CR) is a potent intervention for suppressing cancer. However, CR is generally not appropriate for children. This study, therefore, examined to see if adult‐onset CR influences the lifetime cancer risk in mice after early‐life exposure to ionizing radiation. Infant male mice (1‐week‐old) were exposed to 3.8 Gy X‐rays, fed a control 95 kcal/week or CR 65 kcal/week diet from 7 weeks of age (adult stage), and their lifespan and tumor development were assessed. Irrespective of CR, X‐rays shortened lifespan by 38%, and irrespective of irradiation CR extended lifespan by 20%. Thymic lymphoma (TL) and early‐occurring non‐TL were induced by radiation. The liver and Harderian gland were more susceptible to radiation‐induced tumors than the lungs and non‐thymic lymphoid tissues (late occurring). CR reduced the risk of hepatocellular carcinoma, late‐occurring non‐TL, lung tumor, Harderian tumor, and hemangioma but had less impact on TL and early‐occurring non‐TL. Most notably, the effects of X‐rays on induction of lung tumors, late‐occurring non‐TL and hemangioma were essentially canceled by CR. The ability of CR to prevent late‐occurring tumors was the same for non‐irradiated and irradiated mice, indicating that the mechanism by which CR influences cancer is independent of irradiation. Our results indicate that adult‐onset CR significantly inhibits late‐occurring tumors in a tissue‐dependent manner regardless of infant radiation exposure.     

Metabolic syndrome and hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most rapidly increasing cause of cancer death in the United States. Although many risk factors for HCC are well defined, including hepatitis B virus (HBV), hepatitis C virus (HCV), and alcohol, most series have indicated that 5% to 30% of patients with HCC lack a readily identifiable risk factor for their cancer. The majority of “cryptogenic” HCC in the United States is attributed to nonalcoholic fatty liver disease (NAFLD), a hepatic manifestation of the metabolic syndrome. The metabolic syndrome is a constellation of problems that includes insulin resistance, obesity, hypertension, and hyperlipidemia. Increasingly, components of the metabolic syndrome are being linked to various forms of cancer with respect to both increased risk of disease and worsened outcome. In this review, the authors focused on the relation between metabolic syndrome and HCC. They investigated the increased risks of HCC among individuals with features of metabolic syndrome, potentially worsened cancer outcomes in these patients, possible pathogenic mechanisms to explain these relations, and treatment options for those with NAFLD and its progressive counterpart, nonalcoholic steatohepatitis. It is predicted that metabolic syndrome will lead to large increases in the incidence of HCC over the next decades. A better understanding of the relation between these 2 diseases ultimately should lead to improved screening and treatment options for patients with HCC. Cancer 2009. © 2009 American Cancer Society.     

A suppressive role of ionizing radiation-responsive miR-29c in the development of liver carcinoma via targeting WIP1

Hepatocellular carcinoma (HCC) is the third most common cause of cancer-related deaths worldwide, and it has been linked to radiation exposure. As a well-defined oncogene, wild-type p53-induced phosphatase 1 (WIP1) plays an inhibitory role in several tumor suppressor pathways, including p53. WIP1 is amplified and overexpressed in many malignancies, including HCC. However, the underlying mechanisms remain largely unknown. Here, we show that low-dose ionizing radiation (IR) induces miR-29c expression in female mouse liver, while inhibiting its expression in HepG2, a human hepatocellular carcinoma cell line which is used as a model system in this study. miR-29c expression is downregulated in human hepatocellular carcinoma cells, which is inversely correlated with WIP1 expression. miR-29c attenuates luciferase activity of a reporter harboring the 3′UTR binding motif of WIP1 mRNA. Ectopic expression of miR-29c significantly represses cell proliferation and induces apoptosis and G1 arrest in HepG2. In contrast, the knockdown of miR-29c greatly enhances HepG2 cell proliferation and suppresses apoptosis. The biological effects of miR-29c may be mediated by its target WIP1 which regulates p53 activity via dephosphorylation at Ser-15. Finally, fluorescence in situ hybridization (FISH) and immunohistochemical analyses indicate that miR-29c is downregulated in 50.6% of liver carcinoma tissues examined, whereas WIP1 is upregulated in 45.4% of these tissues. The expression of miR-29c inversely correlates with that of WIP1 in HCC. Our results suggest that the IR-responsive miR-29c may function as a tumor suppressor that plays a crucial role in the development of liver carcinoma via targeting WIP1, therefore possibly representing a target molecule for therapeutic intervention for this disease.     

亚砷酸联合电离辐射作用于肝癌细胞株HepG2后对多药耐药基因MRP1和凋亡相关基因caspase3表达的影响

目的:探究亚砷酸联合电离辐射作用于肝癌细胞株HepG2后对多药耐药基因MRP1和凋亡相关基因caspase 3表达的影响.方法:采用Hoechest染色法检测亚砷酸处理、照射处理及联合处理对细胞凋亡的影响.采用qRT-PCR及Western-blot检测不同处理后HepG2细胞中MRP1和caspase 3的表达水平.结果:亚砷酸联合电离辐射可显著诱导细胞凋亡,显著增强caspase 3的表达,显著降低MRP1的表达.结论:亚砷酸联合电离辐射可通过增加caspase 3的表达诱导HepG2细胞凋亡,并有可能通过下调多药耐药基因MRP1的表达来降低肝癌细胞的耐药性.     

亚砷酸联合电离辐射作用于肝癌细胞株 HepG2 的实验观察

目的：探讨亚砷酸对肝癌细胞株HepG2的放疗增敏作用.方法：采用细胞培养及传代方法,加入不同浓度亚砷酸,48h后用四唑盐实验（MTT）法检测肝癌细胞株HepG2的抑制率.不同剂量6兆伏X射线照射肝癌细胞株,48h后用平板克隆形成实验观察存活分数.结果：在一定浓度范围内（1.25-10mg/ml）,亚砷酸对HepG2细胞增殖的抑制呈浓度依赖性;亚砷酸联合放疗能降低HepG2细胞存活分数,可以使细胞存活曲线的D0值从单纯放疗组的1.94降至1.75,放射增敏比为1.38.结论：亚砷酸对肝癌细胞株HepG2具有放疗增敏作用.     

肝细胞肝癌伴门静脉/下腔静脉癌栓接受与不接受放射治疗的比较

目的探讨肝细胞肝癌患者伴门静脉和或下腔静脉癌栓接受外放射治疗的疗效。方法回顾总结近8年180例原发性肝细胞肝癌伴门静脉和或下腔静脉癌栓患者,其中66例接受直线加速器外放疗作为放疗组,114例未接受外放疗作为对照组,放疗组与对照组间影响患者的主要预后因素除肿瘤标志物有差别外,其他因素无明显差别。放疗组放疗方法为常规分割,局部放疗癌栓,放射治疗剂量介于36～60Gy(中位50Gy)。放射治疗中及治疗后随访肝功能、影像学检查和生存情况。应用Cox回归模型,多因素分析比较两组的生存期。结果66例癌栓患者接受外放射治疗,22例(33.3%)患者癌栓完全缓解,16例(24.2%)部分缓解,26例(39.4%)稳定,2例(3.1%)进展;1年生存率27.9%,中位生存期7.3个月。对照组1年生存率为12.3%,中位生存期为4个月。多因素回归分析显示,外放射治疗显示出很强的保护因素(RR=0.408,P<0.001)。放疗组病人生存情况与甲胎蛋白水平无关;但与γ-GT水平、肝内病灶单多发、癌栓存在的部位有关。死亡原因多为肝内肿瘤未控制导致肝衰。对照组下腔静脉系统癌栓患者生存情况比门静脉癌栓患者差,相反,放疗组下腔静脉癌栓患者的生存情况好于门静脉癌栓患者。结论结合外放射治疗可明显延长肝细胞肝癌伴有门静脉和或下腔静脉癌栓患者的生存期,肝内原发肿瘤灶为单发的癌栓患者,放射治疗更能延长其生存期。     

Significance of Plk1 regulation by miR‐100 in human nasopharyngeal cancer

Polo‐like kinase 1 (Plk1) is a critical regulator of many stages of mitosis; increasing evidence indicates that Plk1 overexpression correlates with poor clinical outcome, yet its mechanism of regulation remains unknown. Hence, a detailed evaluation was undertaken of Plk1 expression in human nasopharyngeal cancer (NPC), the cellular effects of targeting Plk1 using siRNA in combination with ionizing radiation (RT) and potential upstream microRNAs (miRs) that might regulate Plk1 expression. Using immunohistochemistry, Plk1 was observed to be overexpressed in 28 of 40 (70%) primary NPC biopsies, which in turn was associated with a higher likelihood of recurrence (p = 0.018). SiPlk1 significantly inhibited Plk1 mRNA and protein expression, and decreased Cdc25c levels in NPC cell lines. This depletion resulted in cytotoxicity of C666‐1 cells, enhanced by the addition of RT, mediated by G2/M arrest, increased DNA double‐strand breaks, apoptosis, and caspase activation. Immunofluorescence demonstrated that the G2/M arrest was associated with aberrant spindle formation, leading to mitotic arrest. In vivo, transfection of C666‐1 cells and systemic delivery of siPlk1 decreased tumour growth. MicroRNA‐100 (miR‐100) was predicted to target Plk1 mRNA, which was indeed underexpressed in C666‐1 cells, inversely correlating with Plk1 expression. Using luciferase constructs containing the 3′‐UTR of Plk1 sequence, we document that miR‐100 can directly target Plk1. Hence, our data demonstrate for the first time that underexpressed miR‐100 leads to Plk1 overexpression, which in turn contributes to NPC progression. Targeting Plk1 will cause mitotic catastrophe, with significant cytotoxicity both in vitro and in vivo, underscoring the important therapeutic opportunity of Plk1 in NPC.     

The effects of graded levels of calorie restriction: I. impact of short term calorie and protein restriction on body composition in the C57BL/6 mouse

Faced with reduced levels of food, animals must adjust to the consequences of the shortfall in energy. We explored how C57BL/6 mice withdrew energy from different body tissues during three months of food restriction at graded levels up to 40% (calorie restriction: CR). We compared this to the response to equivalent levels of protein restriction (PR) without a shortfall in calories. Under CR there was a dynamic change in body mass over 30 days and thereafter it stabilized. The time to reach stability was independent of the level of restriction. At the end of three months whole body dissections revealed differential utilization of the different tissues. Adipose tissue depots were the most significantly utilized tissue, and provided 55.8 to 60.9% of the total released energy. In comparison, reductions in the sizes of structural tissues contributed between 29.8 and 38.7% of the energy. The balance was made up by relatively small changes in the vital organs. The components of the alimentary tract grew slightly under restriction, particularly the stomach, and this was associated with a parallel increase in assimilation efficiency of the food (averaging 1.73%). None of the changes under CR were recapitulated by equivalent levels of PR.     

Inhibition of human esophageal squamous cell carcinomas by targeted silencing of tumor enhancer genes： an overview

Esophageal cancer has been reported as the ninth most common malignancy and ranks as the sixth most frequent cause of death worldwide. Esophageal cancer treatment involves surgery, chemotherapy, radiation therapy, or combination therapy. Novel strategies are needed to boost the oncologic outcome. Recent advances in the molecular biology of esophageal cancer have documented the role of genetic alterations in tumorigenesis. Oncogenes serve a pivotal function in tumorigenesis. Targeted therapies are directed at the unique molecular signature of cancer cells for enhanced efficacy with low toxicity. RNA interference（RNAi） technology is a powerful tool for silencing endogenous or exogenous genes in mammalian cells. Related results have shown that targeting oncogenes with siRNAs, specifically the mRNA, effectively reduces tumor cell proliferation and induces apoptotic cell death. This article will briefly review studies on silencing tumor enhancer genes related to the induction of esophageal cancer.     

亚砷酸联合电离辐射对肝癌细胞株HepG2增殖、迁移及侵袭能力的影响

目的:探究亚砷酸联合电离辐射对肝癌细胞株HepG2增殖、迁移及侵袭能力的影响。方法:采用CCK-8及EdU法检测照射处理、亚砷酸处理及联合处理对HepG2细胞增殖能力的影响;采用Transwell法检测上述处理方法对细胞迁移及侵袭能力的影响。结果:肝癌细胞株HepG2经照射、亚砷酸或联合处理后,与对照组相比,增殖能力减弱,处于S期的细胞比例显著降低;迁移及侵袭能力也受到了显著的抑制,其中联合作用效果最明显。结论:亚砷酸联合电离辐射可显著抑制肝癌细胞的增殖、迁移及侵袭能力。     

Radiation therapy for bone metastasis of hepatocellular carcinoma

Background The efficacy of radiation therapy for bone metastasis of hepatocellular carcinoma was examined retrospectively. Methods The effect of radiation therapy for pain and paresis was evaluated in 38 patients who received planned radiation therapy with the total dose ranging from 26 to 60 Gy. The percentage regression of 14 metastatic bone lesions was calculated by using computed tomography: percentage regression=[(pre-radiation therapy tumor volume—postradiation therapy tumor volume)/pre-radiation therapy tumor volume]×100. Results The 1-, 2-, and 5-year survival rates of the 38 patients from the start of the radiation therapy were 30% 18%, and 9.0% respectively. The median survival period was 172 days. Pain relief was obtained in 91% of 44 painful bone metastases. No correlation was observed between the percentage regression and the tumor size. Complete regression of bone metastasis was noted in 6 of 14 patients who could be evaluated with computed tomography. Three of the 6 paiients with complete response have survived for more than 6 years after radiation therapy. Conclusion Radiation therapy is an effective method for palliation of bone metastasis. Although the prognosis of most patients with bone metastasis from hepatocellular carcinoma is poor, some attain longterm survival after treatment.     

Hepatocellular carcinoma with subcutaneous metastasis of the scalp

Background

The majority of subcutaneous metastases from hepatocellular carcinoma (HCC) originate from needle tracks or surgical wound contamination. Non-iatrogenic subcutaneous metastasis from hepatocellular carcinoma was rarely reported.

Case report

A 70-year-old man presented with a mass in his left occipital region of the scalp. The surgical complete resection was performed. The histopathology report of the scalp mass showed a characteristic metastatic HCC. Computed tomography (CT) of the abdomen showed no primary or metastatic lesion in the abdomen; that’s why the adjuvant treatment was not given after the surgery. Five months later, magnetic resonance imaging (MRI) of the brain revealed a 6 × 5.5 cm mass at the left posterior parietal region of the scalp. Second surgery was performed and histopathology of the specimen excised was again metastatic HCC. The external beam radiation therapy (XRT) was administered after the surgery. A follow-up MRI of the brain showed no recurrent disease after 9 months from XRT.

Conclusions

HCCs should be considered in the differential diagnosis of carcinomas metastatic to the skin, even in the absence of liver symptoms.     

Fractionated gamma-irradiation renders tumour cells more responsive to apoptotic signals through CD95.

Signals through the CD95 surface receptor can specifically induce apoptosis. Some tumour cell lines are sensitive to CD95 signals, and insensitive cells can be converted to a sensitive phenotype if given appropriate treatment. To determine whether the apoptotic response of tumour cells to signalling through CD95 might be enhanced by ionizing irradiation, carcinoma cells were treated with either single-dose or fractionated gamma-irradiation. The response to treatment with an agonist anti-CD95 antibody was enhanced by pretreatment with either a single large dose or daily fractionated radiation. Fractionated irradiation induced cumulative and prolonged up-regulation of CD95 expression in cell lines bearing functional p53. Since two of four cell lines exhibiting heightened responsiveness to CD95-mediated signals following fractionated irradiation express mutant p53 and displayed little or no up-regulation of CD95, enhanced responsiveness did not correlate with p53 status and CD95 up-regulation. Continuous inhibition of CD95/CD95-ligand interactions during fractionated irradiation provided no protective effect to cells, arguing that autologous CD95/CD95-ligand interactions did not contribute to the direct lethal effect of irradiation. We conclude that fractionated gamma-irradiation provides an extended period of time when carcinoma cells are more responsive to CD95-mediated signals in vitro.     

The effects of graded levels of calorie restriction: III. Impact of short term calorie and protein restriction on mean daily body temperature and torpor use in the C57BL/6 mouse

A commonly observed response in mammals to calorie restriction (CR) is reduced body temperature (T_b). We explored how the T_b of male C57BL/6 mice responded to graded CR (10 to 40%), compared to the response to equivalent levels of protein restriction (PR) over 3 months. Under CR there was a dynamic change in daily T_b over the first 30–35 days, which stabilized thereafter until day 70 after which a further decline was noted. The time to reach stability was dependent on restriction level. Body mass negatively correlated with T_b under ad libitum feeding and positively correlated under CR. The average T_b over the last 20 days was significantly related to the levels of body fat, structural tissue, leptin and insulin-like growth factor-1. Some mice, particularly those under higher levels of CR, showed periods of daily torpor later in the restriction period. None of the changes in T_b under CR were recapitulated by equivalent levels of PR. We conclude that changes in T_b under CR are a response only to the shortfall in calorie intake. The linear relationship between average T_b and the level of restriction supports the idea that T_b changes are an integral aspect of the lifespan effect.