人端粒酶逆转录酶启动子在裸鼠中增强人喉癌对基因放射治疗的敏感性

目的 探索人端粒酶逆转录酶启动子(hTERTp)介导自杀基因辣根过氧化酶(HRP)-吲哚乙酸(IAA)系统联合射线,对相同来源而放射敏感性不同的人喉癌移植瘤模型的治疗作用.方法 建立相同来源而放射敏感性不同的人喉癌(Hep-2和Hep-2R细胞)移植瘤模型,并分为联合治疗组(A组和AR组)、基因治疗组(B组和BR组)、单纯放射组(C组和CR组)和对照组(D组和DR组).瘤内注射脂质体包裹的质粒phTERTp-HRP,腹腔内注射IAA从并联合放疗30 Gy,观察对移植瘤生长的抑制作用.应用原位末端转移酶标记技术(TUNEL)检测肿瘤细胞的凋亡情况;应用AP法检测瘤内HRP蛋白的表达.结果 裸鼠移植瘤生长以联合治疗组最慢,以对照组最快.A组的肿瘤抑制率为54.8%,B组为10.0%,C组为31.9%,AR组为52.7%,BR组为24.8%,CR组为17.0%.A组和AR组可见大量肿瘤细胞坏死和凋亡,凋亡指数分别为16.6%±1.3%和17.6%±1.3%,高于其他组(P<0.05).B组的HRP蛋白表达率(21.9%±5.7%)低于BR组和(33.3%±8.9%),辐射诱导后,A组和AR组的HRP蛋白表达率分别增加2.1和1.6倍(P<0.05).结论 在不同放射敏感性的喉癌移植瘤模型中,hTERTp能被射线诱导,并根据瘤内端粒酶活性增强HRP基因的表达.hTERTp·HRP-IAA系统通过诱导肿瘤细胞凋亡和引起细胞坏死,抑制裸鼠移植瘤生长,并与射线协同作用,起到放射增敏作用.     

射线联合嵌合启动子介导的自杀基因对肿瘤细胞的靶向杀伤作用

目的 探讨放射线联合新型嵌合启动子介导辣根过氧化物酶/吲哚乙酸(HRP/IAA)自杀基因系统特异高效的抗肿瘤作用.方法 构建含有4个串联放射反应元件CArG、含或不含巨细胞病毒(CMV)启动子的人端粒酶逆转录酶嵌合启动子,筛选肿瘤特异性及放射诱导性强的嵌合启动子,下游连接自杀基因辣根过氧化物酶(HRP),检测放射线联合基因治疗对肿瘤细胞HeLa、A549和MHCC97增殖及凋亡的影响.结果 人胚肺成纤维细胞MRC-5中C4-hTC嵌合启动子的活性(0.1±0.0)明显低于肿瘤细胞株HeLa、A549和MHCC97(0.6±0.0、1.1±0.1和1.0±0.1,P＜0.01),经过6 Gy射线诱导后,这种差异更加显著(活性分别为0.2±0.1、1.7±0.2、2.3±0.2和2.3±0.1,P＜0.01).在肿瘤细胞株HeLa、A549和MHCC97中,嵌合启动子C4-hTC-HRP携带的自杀基因系统SER值分别为2.64、2.75和2.82,显著高于单纯hTERT启动子.在肿瘤细胞中,除阴性对照质粒pGL3-control-Luc外,自杀基因与放射治疗相联合对肿瘤细胞的生长抑制明显高于单一治疗方法,而联合组中pC4-hTC-HRP/IAA系统与放射联合的生长抑制作用最显著,对HeLa、A549和MHCC97细胞的生长抑制率分别为67.3%、69.0%和64.6%.在肿瘤细胞中,除阴性对照质粒pGL3-control-Luc外,联合组诱导的早期凋亡率明显高于单一治疗方法组,其中pC4-hTC-HRP/IAA系统与放射联合诱导的凋亡率最高,HeLa、A549和MHCC97细胞凋亡率分别为39.6%、33.0%和33.2%.结论 新型嵌合启动子C4-hTC具有良好的肿瘤特异性及放射诱导性,放射线联合基因治疗对肿瘤细胞具有特异高效的杀伤作用,在肿瘤的基因放疗中具有较强的应用潜力.

Abstract：

Objective To explore the synergistic anti-tumor effect of radiotherapy and horseradish peroxidase/prodrug indole-3-acetic acid (HRP/IAA) gene therapy system using chimeric hTERT promoter responsive to ionizing radiation.Methods The synthetic hTERT promoters containing four tandem-repeat copies of radio-inducible CArG elements, and the chimeric promoter containing cytomegalovirus (CMV)early promoter were both constructed.The activities of the chimeric promoters in cancer cell lines ( HeLa,A549, and MHCC97 ) and normal cell line ( MRC-5 ) were detected using luciferase reporter gene expression analysis after a 60 Co γ-irradiation treatment at a series of doses (a single dose of 0 to 10 Gy).The anti-tumor effect of combining irradiation with HRP/IAA gene-directed enzyme prodrug therapy system controlled by the chimeric promoter was tested by colony formation assay, cell counting and apoptosis analysis.Results The chimeric promoters were ineffective in normal human cells, even after irradiation, but the expression of luciferase gene in tumor cells was significantly higher.The activity of the chimeric promoter in MRC-5 cells was 22.3%, 12.9% and 13.6% of that in HeLa, A549 and MHCC97 cells, respectively.After irradiation,the ratios were 11.7%, 8.7% and 8.8%, respectively.Furthermore, the chimeric promoters could successfully induce the expression of luciferase gene following different doses of radiation, with maximal inducible activity seen after 6 Gy irradiation.The chimeric promoter containing four tandem-repeat copies of radio-inducible CArG elements and CMV early promoter showed the highest activity with 6 Gy irradiation.The relative luciferase activities in HeLa, A549 and MHCC97 cells were 1.7 ± 0.2, 2.3 ± 0.2 and 2.3±0.1, respectively.The chimeric promoter mediated suicide gene therapy system could increase radiosensitivity in different cancer cells.Compared with the control system, it plus irradiation showed stronger cell proliferation inhibition, 67.3% vs.26.1% in HeLa, 69.0% vs.28.3% in A549, 64.6% vs.20.8% in MHCC97 cells, and also higher apoptosis-inducing effect, 39.6% vs.14.2% in HeLa, 33.0% vs.12.4%in A549, and 33.2% vs.14.2% in MHCC97 cells.Conclusions Chimeric promoter containing hTERT promoter, CArG elements and CMV promoter preserve the tumor-specificity in telomerase-positive tumor cells, and irradiation-responsive to low dose of radiation.The suicide gene therapy using this promoter plus radiotherapy show a strong anti-tumor effect in vitro.It is expected to have a good potential for future application in gene radiotherapy.     

ERp57 modulates STAT3 activity in radioresistant laryngeal cancer cells and serves as a prognostic marker for laryngeal cancer

Although targeting radioresistant tumor cells is essential for enhancing the efficacy of radiotherapy, the signals activated in resistant tumors are still unclear. This study shows that ERp57 contributes to radioresistance of laryngeal cancer by activating STAT3. Increased ERp57 was associated with the radioresistant phenotype of laryngeal cancer cells. Interestingly, increased interaction between ERp57 and STAT3 was observed in radioresistant cells, compared to the control cells. This physical complex is required for the activation of STAT3 in the radioresistant cells. Among STAT3-regulatory genes, Mcl-1 was predominantly regulated by ERp57. Inhibition of STAT3 activity with a chemical inhibitor or siRNA-mediated depletion of Mcl-1 sensitized radioresistant cells to irradiation, suggesting that the ERp57-STAT3-Mcl-1 axis regulates radioresistance of laryngeal cancer cells. Furthermore, we observed a positive correlation between ERp57 and phosphorylated STAT3 or Mcl-1 and in vivo interactions between ERp57 and STAT3 in human laryngeal cancer. Importantly, we also found that increased ERp57-STAT3 complex was associated with poor prognosis in human laryngeal cancer, indicating the prognostic role of ERp57-STAT3 regulation. Overall, our data suggest that ERp57-STAT3 regulation functions in radioresistance of laryngeal cancer, and targeting the ERp57-STAT3 pathway might be important for enhancing the efficacy of radiotherapy in human laryngeal cancer.     

靶向HRP/IAA自杀基因系统联合IL-12基因治疗Lewis肺癌的研究

目的:观察人端粒酶逆转录酶(hTERT)启动子驱动辣根过氧化物酶(HRP)/吲哚乙酸(IAA)系统联合白细胞介素-12(IL-12)基因对小鼠Lewis肺癌的疗效。方法:建立Lewis肺癌移植瘤模型,随机分为对照组、HRP组、IL-12组和联合组,分别给予AdCMVGFP、AdhTERTHRP、AdCMVmIL-12单一或联合注射,然后腹腔注射IAA,观察肿瘤生长情况。蛋白质印迹法和ELISA检测瘤组织HRP和IL-12表达;免疫组化检测瘤组织内CD4+、CD8+淋巴细胞浸润情况。结果:与对照组、单一治疗组相比,联合组小鼠肿瘤生长受到显著抑制(联合组vs对照组:P=0.000,9 d;联合组vsHRP组:P=0.005,15 d;联合组vsIL-12组:P=0.046,12 d),生存期显著延长(联合组vs对照组:χ2=9.529,P=0.002;联合组vsHRP组:χ2=9.039,P=0.003;联合组vsIL-12组:χ2=8.595,P=0.003),肿瘤组织广泛坏死,CD4+、CD8+淋巴细胞浸润显著增多。结论:IL-12基因治疗可诱导宿主产生抗肿瘤免疫应答,与靶向HRP/IAA自杀基因系统联合具有...     

Attenuation of telomerase activity by hammerhead ribozyme targeting human telomerase RNA induces growth retardation and apoptosis in human breast tumor cells

Ribozyme possesses specific endoribonuclease activity and catalyzes the hydrolysis of specific phosphodiester bonds, which results in the cleavage of target RNA sequences. Here, we evaluated the ability of hammerhead ribozymes targeting human telomerase RNA (hTR) to inhibit the catalytic activity of telomerase and the proliferation of cancer cells. Hammerhead ribozymes were designed against 7 NUX sequences located in open loops of the hTR secondary structure. We verified the ribozyme specificity by in vitro cleavage assay by using a synthetic RNA substrate. Subsequently, we introduced ribozyme expression vector into human breast tumor MCF-7 cells and assessed the biologic effects of ribozyme. Hammerhead ribozyme R1 targeting the template region of hTR efficiently cleaved hTR in vitro, and stable transfectants of this ribozyme induced the degradation of target hTR RNA and attenuated telomerase activity in MCF-7 cells. Moreover, the ribozyme R1 transfectant displayed a significant telomere shortening and a lower proliferation rate than parental cells. Clones with reduced proliferation capacity showed enlarged senescence-like shapes or highly differentiated dendritic morphologies of apoptosis. In conclusion, the inhibition of telomerase activity by hammerhead ribozyme targeting the template region of the hTR presents a promising strategy for inhibiting the growth of human breast cancer cells.     

Bcl-2 expression predicts radiotherapy failure in laryngeal cancer

Early stage laryngeal cancer can be effectively cured by radiotherapy or conservative laryngeal surgery. In the UK, radiotherapy is the preferred first line treatment. However, up to 25% of patients with T2 tumours will demonstrate locally persistent or recurrent disease at the original site, requiring salvage surgery to achieve a definitive cure. Patients experiencing treatment failure have a relatively poor prognosis. A retrospective analysis was conducted consisting of 124 patients with early stage (T1-T2, N0) laryngeal squamous cell carcinoma. In total, 62 patients who failed radiotherapy were matched for T stage, laryngeal subsite and smoking history to a group of 62 patients successfully cured by radiotherapy. Using immunohistochemistry the groups were compared for expression of apoptotic proteins: bcl-2, bcl-X(L), bax, bak and survivin. Radioresistant laryngeal cancer was associated with bcl-2 (P < 0.001) and bcl-X(L) (P = 0.005) expression and loss of bax expression (P = 0.012) in pretreatment biopsies. Bcl-2 has an accuracy of 71% in predicting radiotherapy outcome. The association between expression of bcl-2, bcl-X(L) and bax with radioresistant cancer suggests a potential mechanism by which cancer cells avoid the destructive effects of radiotherapy. Predicting radioresistance, using bcl-2, would allow the clinician to recommend conservative laryngeal surgery as an alternative first line treatment to radiotherapy.     

Increased aldehyde reductase expression mediates acquired radioresistance of laryngeal cancer cells via modulating p53

The main obstacle to cure tumors by radiotherapy has been ascribed to tumor radioresistance. To determine the mechanisms underlying resistance to irradiation, it is essential to compare proteins differentially expressed from radiotherapy-sensitive and -resistant cancer cells. Aldehyde reductase (AKR1A1) was recently identified as increased in radioresistant laryngeal cancer cells by comparative proteomics approach. Here, we provide the mechanism of AKR1A1-mediated radioresistance via p53 regulation in laryngeal cancer cells. AKR1A1 induction was correlated with the radioresistant phenotype of laryngeal cancer HEp-2 cells. AKR1A1 depletion with siRNA significantly enhanced radiation sensitivity of radioresistant HEp-2 cells by promoting radiation-induced cell death and accelerated radiation-mediated inhibition of cell proliferation, without affecting either the PI3K-Akt or MAPK-ERK pathways. Intriguingly, AKR1A1 depletion induced phosphorylation of p53 at serine 15 and G 2/M transition in response to irradiation. We further found that AKR1A1 interacted with p53 and this interaction was dramatically increased in the irradiated radioresistant cells compared with the control cells. AKR1A1 expression also regulated p53 stability in response to irradiation. Furthermore, AKR1A1 depletion only sensitized HCT116 cells expressing p53 to irradiation and not p53-deficient cells. Therefore, our data suggest that radiation-inducible AKR1A1 contributes to acquired radioresistance of laryngeal cancer cells by suppressing p53 activation through inhibitory interaction.     

Radioresistant human lung adenocarcinoma cells that survived multiple fractions of ionizing radiation are sensitive to HSP90 inhibition

Despite the common usage of radiotherapy for the treatment of NSCLC, outcomes for these cancers when treated with ionizing radiation (IR) are still unsatisfactory. A better understanding of the mechanisms underlying resistance to IR is needed to design approaches to eliminate the radioresistant cells and prevent tumor recurrence and metastases. Using multiple fractions of IR we generated radioresistant cells from T2821 and T2851 human lung adenocarcinoma cells. The radioresistant phenotypes present in T2821/R and T2851/R cells include multiple changes in DNA repair genes and proteins expression, upregulation of EMT markers, alterations of cell cycle distribution, upregulation of PI3K/AKT signaling and elevated production of growth factors, cytokines, important for lung cancer progression, such as IL-6, PDGFB and SDF-1 (CXCL12). In addition to being radioresistant these cells were also found to be resistant to cisplatin.HSP90 is a molecular chaperone involved in stabilization and function of multiple client proteins implicated in NSCLC cell survival and radioresistance. We examined the effect of ganetespib, a novel HSP90 inhibitor, on T2821/R and T2851/R cell survival, migration and radioresistance. Our data indicates that ganetespib has cytotoxic activity against parental T2821 and T2851 cells and radioresistant T2821/R and T2851/R lung tumor cells. Ganetespib does not affect proliferation of normal human lung fibroblasts. Combining IR with ganetespib completely abrogates clonogenic survival of radioresistant cells.Our data show that HSP90 inhibition can potentiate the effect of radiotherapy and eliminate radioresistant and cisplatin -resistant residual cells, thus it may aid in reducing NSCLC tumor recurrence after fractionated radiotherapy.     

人端粒酶逆转录酶mRNA在胃癌组织中的定量表达及其与胃癌预后的关系

目的 探讨人端粒酶逆转录酶(hTERT)mRNA在胃癌组织中的表达,及其与胃癌生物学行为和根治术后患者预后的关系.方法 应用荧光定量逆转录聚合酶链反应(RT-PCR)检测89例胃癌根治性切除术后患者的肿瘤组织和阴性切缘组织中hTERT mRNA的表达量,对hTERT mRNA表达量与患者的临床病理参数(年龄、性别、肿瘤大小、肿瘤部位、病理类型、组织分化程度、浸润深度、淋巴结转移情况、pTNM分期及生存期)进行单因素分析,采用Cox模型进行胃癌患者生存的多因素分析.结果 hTERT mRNA在阴性切缘组织中的表达量为11.37±2.15,在胃癌组织中的表达量为16.98±3.56,差异有统计学意义(P<0.05).胃癌组织中hTERT mRNA的表达量与组织学分级、浸润深度、pTNM分期及淋巴结转移呈正相关(P<0.05),与胃癌患者的生存期呈负相关(P<0.01).结论 胃癌组织中hTERT mRNA高表达表明胃癌恶性程度较高且病期较晚,检测胃癌组织中hTERTmRNA的表达水平有助于对胃癌患者的预后做出更准确的判断.胃癌组织中hTERT mRNA的表达量、肿瘤浸润深度和pTNM分期是影响胃癌患者预后的重要因素.

Abstract：

Objective By quantitative detection of telomerase expression, we investigated the relationship between telomerase expression and malignant behavior and prognosis in gastric carcinoma.Methods A real-time quantitative RT-PCR (RQ-PCR) was used to quantify the hTERT mRNA copy numbers in 89 samples of gastric carcinoma and corresponding non-cancerous tissues.The clinicopathological data of enrolled patients such as age, sex, tumor size, tumor site, pathologic type, histodifferentiation,infiltration depth, lymph node metastasis, stage and survival were obtained, and were made one factor analysis of variance and COX regression prognostic analysis with those above mentioned markers.Follow-up was completed as of February 28, 2010.The median follow-up was 24 months.Results hTERT from gastric carcinomas and corresponding non-cancerous tissues was 16.98 ± 3.56 and 11.37 ± 2.15, respectively (P<0.05 ),the telomerase activity in gastric cancer was significantly higher than that in non-cancerous tissue ( P < O.05 ).Telomerase activity showed a positive correlation with depth of invasion, tumor differentiation and nodal metastasis ( P < 0.01 ), and negative correlation with survival.Conclusions Gastric cancer with high hTERT mRNA expression indicates a more malignant potential.Detection of hTERT mRNA in gastric cancer may be useful in a better understanding of invasion, metastasis, as well as prognosis of gastric cancer and provide a more efficient therapy.The quantitative expression of hTERT mRNA, infiltration depth and pTNM stage are significant afactors affecting the prognosis of patients with gastric carcinoma.     

端粒酶催化亚基hTERT在肿瘤治疗中的研究进展

人端粒酶催化亚基hTERT基因转录的从头激活是端粒酶活化的限速步骤，受到多种癌基因和抑癌基因产物的精密调控。构建hTERT启动子调控抗肿瘤基因的逆转录病毒载体，使抗肿瘤基因在端粒酶阳性的肿瘤细胞内定向表达，有望用于肿瘤基因治疗。本文首先简单介绍了hTERT蛋白的结构和表达调控机制，然后对其在肿瘤发生发展中的生物治疗的功能作一简要综述。     

Mucoepidermoid carcinoma of the larynx: a case which responded completely to radiotherapy and a review of the literature

Most laryngeal cancers are squamous cell carcinomas, and adenocarcinomas account for < 1% of cancers of the larynx. Among them, mucoepidermoid carcinoma is extremely rare and there is little agreement about the treatment of this carcinoma. We encountered one patient with mucoepidermoid carcinoma of the bilateral vocal cords (T1bN0M0, Stage 1). For this, most investigators recommended a surgical procedure. However, because of his old age, the early stage and low grade of histopathology, we treated this patient with radiotherapy alone, delivered by accelerated hyperfractionation, which is a more effective strategy for treating radioresistant tumors than conventional irradiation. Following radiotherapy, the tumor disappeared and the patient has been alive and well for more than six years. An old patient with mucoepidermoid carcinoma of the larynx was successfully treated with radiotherapy alone.      

Radioresistant tumor cells are present in head and neck carcinomas that recur after radiotherapy

We determined the in vitro survival parameters of 14 human head and neck squamous cell carcinoma tumor cell lines cultured from patients who suffered local failure after a curative course of radiotherapy. The radiobiological parameters determined included D, D0, n, and surviving fractions at 100, 200, and 300 cGy. When compared to in vitro radiobiological parameters of tumor cells cultured from head and neck cancer patients prior to radiotherapy, human sarcoma cell lines derived from patients not receiving therapeutic radiation, normal human diploid fibroblasts or other human tumor cell lines reported in the literature, the human tumor cells derived from radiotherapy failures are radioresistant.     

hTERT启动子调控的SEA-CD80基因共表达重组腺病毒载体的构建及在不同肿瘤细胞中的表达鉴定

目的：构建肿瘤靶向性葡萄球菌肠毒素 A 和 CD80基因共表达重组腺病毒载体。方法：采用 PCR 技术从质粒 pShuttle - AFP - CD80扩增人 CD80全长 cDNA 片段,克隆至已构建载体 pMD18- T - BIS,取代小鼠CD80 cDNA 片段。重组质粒命名为 pMD18- T - hBIS。经酶切,将 CWV 增强子修饰的人端粒酶反转录酶启动子从已构建载体 pGL3- CWVE - hTP,亚克隆至穿梭质粒 pShuttle2,然后经酶切将片段 hCD80- IRES - SEA从 pMD18- T - hBIS 质粒亚克隆至 CWV 增强子修饰的人端粒酶反转录酶启动子下游,构建质粒 pShuttle2-CE - hTP - hBIS。再与腺病毒骨架质粒 pAdEasy -1共转化 E. coli BJ5183,以获得的重组子（命名为 Ad - CE- hTP - BIS）转染 Ad293细胞制备病毒并纯化。将病毒分别感染人肝癌细胞 H7721、宫颈癌细胞株 Hela 细胞和原代培养的人牙龈成纤维细胞,经免疫荧光染色后,激光共聚焦显微镜观察 SEA 和 CD80在细胞膜的表达情况。结果：重组腺病毒能够使 CD80和 SEA 在人肝癌细胞 H7721、宫颈癌细胞株 Hela 细胞膜上共表达,而在人牙龈成纤维细胞中不表达。结论：成功地构建了多肿瘤靶向性 SEA 和 CD80基因共表达重组腺病毒载体。为应用 SEA 和 CD80基因对人多种肿瘤进行靶向基因治疗奠定了基础。     

端粒酶永生化原始乳腺癌组织来源细胞及其意义

背景与目的：乳腺癌细胞系大部分来源于乳腺癌转移所致的胸水或非原始乳腺癌组织来源，与真正的乳腺癌的生物学性状有很大差异。而仅部分细胞系直接由乳腺癌原代细胞在体外培养条件下成为永生化的细胞系，过表达人端粒酶逆转录酶（hTERT）可使正常人上皮细胞永生化。本研究将通过hTERT转染人原始乳腺癌组织来源的细胞建立永生化乳腺癌细胞系，并研究过表达hTERT对其他基因表达的影响。方法：通过重组逆转录病毒pBABE-hTERT-puro将hTERT基因导人原始乳腺癌组织来源的细胞，建立稳定表达hTERT的永生乳腺癌细胞。再利用微阵列技术检测乳腺癌细胞中hTERT诱导的基因表达改变。结果：Real-TimeRT-PCR证实hTERT转染后的乳腺癌细胞中hTERT过度并稳定表达，为转染前表达量的1400倍以上，并使得被转染的细胞永生化，可以传40～50代以上。微阵列结果进一步证实hTERT在转染后的细胞中过表达，另外，有22个基因在转染后的乳腺癌细胞中上调，未观察到所有细胞株中均下调的基因。结论：过表达hTERT可导致乳腺癌原代细胞的永生化，并对部分基因有上调作用。     

Classification of sensitivity or resistance of cervical cancers to ionizing radiation according to expression profiles of 62 genes selected by cDNA microarray analysis

To identify a set of genes related to radiosensitivity of cervical squamous cell carcinomas and to establish a predictive method, we compared expression profiles of 9 radiosensitive and 10 radioresistant tumors obtained by biopsy before treatment, on a cDNA microarray consisting of 23,040 human genes. We identified 121 genes whose expression was significantly greater in radiosensitive cells than in radioresistant cells, and 50 genes that showed higher levels of expression in radioresistant cells than in radiosensitive cells. Some of these genes had already known to be associated with the radiation response, such as aldehyde dehydrogenase 1 (ALDH1) and X-ray repair cross-complementing 5 (XRCC5) (P<.05, Mann-Whitney test). The validity of the total of 171 genes as radiosensitivity related genes were certified by permutation test (P<.05). Furthermore, we selected 62 genes on the basis of a clustering analysis, and confirmed the validity of these genes with cross-validation test. The cross-validation test also indicates the possibility of making prediction of radiosensitivity for discriminating radiation-sensitive from radiation resistant biopsy samples by predicting score (PS) values calculated from expression values of 62 genes in 19 samples, because the prediction successfully and unequivocally discriminated the radiosensitive phenotype from the radioresistant phenotype in our test panel of 19 cervical carcinomas. The extensive list of genes identified in these experiments provides a large body of potentially valuable information for studying the mechanism(s) of radiosensitivity, and selected 62 genes opens the possibility of providing appropriate and effective radiotherapy to cancer patients.     

Targeting polymerase θ impairs tumorigenesis and enhances radiosensitivity in lung adenocarcinoma

Radioresistance remains a major obstacle to efficacious radiotherapy in non–small-cell lung cancer (NSCLC). DNA replication proteins are novel targets for radiosensitizers. POLQ is a DNA polymerase involved in DNA damage response and repair. We found that POLQ is overexpressed in NSCLC and is clinically correlated with high tumor stage, poor prognosis, increased tumor mutational burden, and ALK and TP5 mutation status; POLQ inhibition impaired lung tumorigenesis. Notably, POLQ expression was higher in radioresistant lung cancer cells than in wild-type cancer cells. Moreover, POLQ expression was further increased in radioresistant cells after radiation. Enhanced radioresistance is through a prolonged G2/M phase and faster repair of DNA damage, leading to reduced radiation-induced apoptosis. Novobiocin (NVB), a POLQ inhibitor, specifically targeted cancer cells. Genetic knockdown of POLQ or pharmacological inhibition by NVB decreased radioresistance in lung adenocarcinoma while causing little toxicity to normal pulmonary epithelial cells. In conclusion, POLQ is a promising and practical cancer-specific target to impair tumorigenesis and enhance radiosensitivity in NSCLC.