A pilot clinical study of treatment guided by personalized tumorgrafts in patients with advanced cancer

Patients with many advanced solid cancers have very poor prognosis, and improvements in life expectancy are measured only in months. We have recently reported the remarkable clinical outcome of a patient with advanced, gemcitabine-resistant, pancreatic cancer who was later treated with DNA-damaging agents, on the basis of the observation of significant activity of this class of drugs against a personalized tumorgraft generated from the patient's surgically resected tumor. Here, we extend the approach to patients with other advanced cancers. Tumors resected from 14 patients with refractory advanced cancers were propagated in immunodeficient mice and treated with 63 drugs in 232 treatment regimens. An effective treatment regimen in the xenograft model was identified for 12 patients. One patient died before receiving treatment, and the remaining 11 patients received 17 prospectively guided treatments. Fifteen of these treatments resulted in durable partial remissions. In 2 subjects, no effective treatments were found. Overall, there was a remarkable correlation between drug activity in the model and clinical outcome, both in terms of resistance and sensitivity. The data support the use of the personalized tumorgraft model as a powerful investigational platform for therapeutic decision making and to efficiently guide cancer treatment in the clinic.     

Next generation sequencing of prostate cancer from a patient identifies a deficiency of methylthioadenosine phosphorylase, an exploitable tumor target

Castrate-resistant prostate cancer (CRPC) and neuroendocrine carcinoma of the prostate are invariably fatal diseases for which only palliative therapies exist. As part of a prostate tumor sequencing program, a patient tumor was analyzed using Illumina genome sequencing and a matched renal capsule tumor xenograft was generated. Both tumor and xenograft had a homozygous 9p21 deletion spanning the MTAP, CDKN2, and ARF genes. It is rare for this deletion to occur in primary prostate tumors, yet approximately 10% express decreased levels of methylthioadenosine phosphorylase (MTAP) mRNA. Decreased MTAP expression is a prognosticator for poor outcome. Moreover, it seems that this deletion is more common in CRPC than in primary prostate cancer. We show for the first time that treatment with methylthioadenosine and high dose 6-thioguanine causes marked inhibition of a patient-derived neuroendocrine xenograft growth while protecting the host from 6-thioguanine toxicity. This therapeutic approach can be applied to other MTAP-deficient human cancers as deletion or hypermethylation of the MTAP gene occurs in a broad spectrum of tumors at high frequency. The combination of genome sequencing and patient-derived xenografts can identify candidate therapeutic agents and evaluate them for personalized oncology.     

乳腺癌易感蛋白2的结构和功能

背景乳腺癌易感蛋白2(breast cancer susceptibility protein 2,BRCA2)是由乳腺癌易感基因2编码的一种在维持哺乳动物细胞染色体稳定及DNA损伤生物应答中发挥重要作用的肿瘤抑制因子.许多研究表明BRCA2蛋白与遗传性乳腺癌、卵巢癌及范康尼氏贫血症的发生具有密切关系,猜测其与双链DNA损伤修复有关,但具体作用模型与机制仍不清楚.目的回顾关于BRCA2蛋白结构与DNA损伤修复的研究,明确BRCA2蛋白在双链DNA损伤修复中的作用机制.研究选择选择关于BRCA2蛋白及DNA损伤修复的文献.数据来源进行全面的检索,检索手段包括电子检索、手工检索及个人通信等.数据提取对检索到的BRCA2蛋白及DNA损伤修复的相关研究文章信息进行综述.主要观察指标BRCA2蛋白的结构及其在DNA损伤修复中的作用模型与机制.结果BRCA2蛋白在肿瘤抑制过程中行使重要功能,其C末端DBD中的DNA结合活性与BRC模体中的RAD51蛋白结合活性在双链DNA损伤修复的同源重组过程中起着直接作用.结论BRCA2蛋白在双链DNA损伤修复中发挥重要作用,但其具体过程与整个信号通路仍需进一步研究证实,其有望开发为治疗与DNA损伤相关疾病的新靶点,为其预防康复提供理论依据.     

宁夏地区回族女性散发性乳腺癌易感基因BRCA1/BRCA2突变的研究

摘要：目的：研究宁夏地区回族女性散发性乳腺癌中BRCA1/BRCA2基因 (breast cancer susceptibility gene 1/2)的突变位点及携带情况。 方法：收集60例回族居民乳腺癌石蜡包埋组织标本及15例乳腺小叶增生或纤维腺瘤标本。PCR和DNA直接测序法检测BRCA1基因第2、11和20号外显子和BRCA2基因第11号部分外显子突变情况。 结果：60例乳腺癌BRCA1基因有10例突变,突变率为16.7%,突变位点均位于BRCA1基因。15例对照均未检出突变且淋巴结转移与未转移组间BRCA1基因突变率差异（30.8%与5.9%）有统计学意义（P＜0.05）。 结论：BRCA1基因突变可能与宁夏回族女性乳腺癌发生相关。     

深圳地区乳腺癌患者BRCA1基因突变分析

目的研究BRCA1基因在乳腺癌中的突变情况,探讨BRCA1基因突变与乳腺癌的关系。方法应用PCR—SSCP分析和DNA直接测序法,检测57例乳腺癌BRCA1第2,5,11,18,20和21外显子基因突变情况。结果57例中共检测出7例突变,其中4例为11外显子的错义突变（3232A〉G）,3例为20外显子的拼接点突变（IVS20—68insA〉A）。乳腺癌BRCA1的基因突变率为12．2％（7／57）。结论BRCA1基因突变与乳腺癌有密切关系。     

抑制Smac基因表达对胰腺癌裸鼠移植瘤生长影响的研究

[目的]探讨Smac基因对人胰腺癌裸鼠移植瘤生长的抑制作用.[方法]于裸鼠腋下接种200 μL 107/mL的PANC-1细胞悬液,建立人胰腺癌裸鼠移植瘤模型,将其分为三组：注射PBS液（A组）、转染空载体（B组）、转染Smac基因（C组）,比较三组移植瘤的大小、移植瘤细胞的凋亡率,移植瘤中Smac蛋白表达和微血管密度（MVD）.[结果]与A、B组比较,C组裸鼠移植瘤体积、质量和MVD显著减小;移植瘤细胞的凋亡指数和Smac蛋白的表达率均明显增高,其差异均有统计学意义（P〈0.05）.[结论]脂质体转染Smac基因能抑制人胰腺癌裸鼠移植瘤的生长,可能与该基因诱导胰腺癌细胞凋亡和抑制肿瘤血管形成有关.     

BRCA1基因与乳腺癌的诊断治疗

乳腺癌易感基因1（BRCA1）是乳腺癌的危险因素之一,是迄今为止发现的与乳腺癌发生相关的最重的抑癌基因。其在遗传性乳腺癌患者中具有高的突变率,已成为国外临床评估女性患乳腺癌风险和指导治疗方案选择的重分子标志物。本文主介绍了BRCA1基因的结构和功能;常用BRCA1基因检测方法,如蛋白质截断测试、单链构象多态性检测、变性高效液相色谱分析技术、多重连接探针扩增技术、高分辨率熔解曲线;BRCA1基因在中国乳腺癌人群中突变情况;BRCA1基因在外科治疗和抗肿瘤药物选择方面中的应用等。     

Oncogenic Kras is required for both the initiation and maintenance of pancreatic cancer in mice

Pancreatic cancer is almost invariably associated with mutations in the KRAS gene, most commonly KRASG12D, that result in a dominant-active form of the KRAS GTPase. However, how KRAS mutations promote pancreatic carcinogenesis is not fully understood, and whether oncogenic KRAS is required for the maintenance of pancreatic cancer has not been established. To address these questions, we generated two mouse models of pancreatic tumorigenesis: mice transgenic for inducible KrasG12D, which allows for inducible, pancreas-specific, and reversible expression of the oncogenic KrasG12D, with or without inactivation of one allele of the tumor suppressor gene p53. Here, we report that, early in tumorigenesis, induction of oncogenic KrasG12D reversibly altered normal epithelial differentiation following tissue damage, leading to precancerous lesions. Inactivation of KrasG12D in established precursor lesions and during progression to cancer led to regression of the lesions, indicating that KrasG12D was required for tumor cell survival. Strikingly, during all stages of carcinogenesis, KrasG12D upregulated Hedgehog signaling, inflammatory pathways, and several pathways known to mediate paracrine interactions between epithelial cells and their surrounding microenvironment, thus promoting formation and maintenance of the fibroinflammatory stroma that plays a pivotal role in pancreatic cancer. Our data establish that epithelial KrasG12D influences multiple cell types to drive pancreatic tumorigenesis and is essential for tumor maintenance. They also strongly support the notion that inhibiting KrasG12D, or its downstream effectors, could provide a new approach for the treatment of pancreatic cancer.     

Targeting the CYP2B 1/cyclophosphamide suicide system to fibroblast growth factor receptors results in a potent antitumoral response in pancreatic cancer models

The CYP2B1/cyclophosphamide (CPA) suicide gene therapy approach has been shown to be highly promising in clinical trials for the treatment of pancreatic cancer. However, delivering the therapeutic gene to a sufficient number of tumor cells able to trigger a complete response remains a challenge. Target-specific delivery of adenovirus to fibroblast growth factor receptors (FGFRs) has been obtained in a variety of tumor models and has been shown to highly increase transduction efficiency. In the present paper we have tested the therapeutic outcome of retargeting the adenoviral vector, Ad-CYP2B1, to FGFRs, using an FGF2-Fab' conjugate, in pancreatic cancer models. First, we show a heterogeneous subcellular distribution of overexpressed FGFR-1 in pancreatic cancer cells. Higher transduction efficiency was observed in five of the six cell lines studied after FGF2-AdGFPLuc infection. Interestingly, an association between FGFR-1 membrane cell expression and viral entry was found. Moreover, tumors injected with FGF2-AdGFPLuc showed enhanced and persistent transgene expression. Importantly, we demonstrate the relevant enhanced cytotoxic effect of the FGF2-Ad-CYP2B]/CPA system in four of the six cell lines studied. Moreover, retargeting Ad-CYP2B1/CPA to FGFRs resulted in a potent antitumoral effect and in an increased survival rate, in two human pancreatic xenograft models. Thus, our results indicate that redirecting adenoviruses to FGFRs highly increases the potency of the suicide system CYP2B1/CPA. Consequently, it may constitute a promising approach to the treatment of patients with pancreatic tumors, in which a high proportion of FGF receptors precisely localize to the plasma membrane.     

Context dependence of checkpoint kinase 1 as a therapeutic target for pancreatic cancers deficient in the BRCA2 tumor suppressor

Inherited mutations in the tumor suppressor BRCA2 are predisposed to pancreatic adenocarcinomas, which carry activating mutations in the KRAS oncogene in more than 95% of cases, as well as frequent TP53 inactivation. Here, we have established an RNA interference (RNAi) screen to identify genes whose depletion selectively inhibits the growth of cells lacking BRCA2, and then studied the effects of the genetic depletion or pharmacologic inhibition of 1 candidate, the checkpoint kinase 1 (CHK1), in the context of pancreatic cancer. Pharmacologic inhibition of CHK1 using small-molecule inhibitors (CHK1i) reduced cell growth in several cell lines depleted of BRCA2. Unexpectedly, these drugs did not suppress the growth of BRCA2-deficient pancreatic cancer cell lines from humans or gene-targeted mice expressing active Kras and trans-dominant inhibitory mutant Trp53. Remarkably, the expression of KRAS(G12V) and TP53(G154V) in BRCA2-depleted HEK293 cells was sufficient to render them resistant to CHK1i (but not to mitomycin C or inhibitors of PARP1). CHK1i sensitivity was restored by gemcitabine, an S-phase genotoxin used to treat pancreatic adenocarcinoma. Thus, the growth-suppressive effect of CHK1 inhibition in BRCA2-mutant tumors can be opposed by concurrent KRAS activation and TP53 mutations typical of pancreatic adenocarcinoma, and CHK1i resistance in this setting can be overcome by gemcitabine. Our findings show that approaches that use potential therapeutic targets for cancer identified in synthetic lethal RNAi screens are affected by the genetic context of specific malignancies and combination therapy with other agents. This concept should be taken into account in the ongoing and future development of targeted cancer therapies.     

靶向高通量测序检测卵巢癌患者易感基因突变与临床特征的相关性研究

目的　探讨卵巢癌易感基因突变与临床特征的关系。方法　采用靶向高通量测序技术对35例卵巢癌患者的外周血进行BRCA1,BRCA2,CHEK2,PALB2,BRIP1,TP53,PTEN,STK11,CDH1,ATM,BARD1,MLH1,MRE11A,MSH2,MSH6,MUTYH,NBN,PMS1,PMS2,RAD50和RAD51C共21种易感基因进行测序,结合临床资料分析基因突变与卵巢癌的相关性。结果　卵巢癌患者多以高级别浆液性卵巢癌晚期为主。35例卵巢癌患者中共检出已知致病突变19例,突变率54.3%,其中BRCA1基因突变7例（20.0%）,BRCA2基因突变4例（11.4%）,RAD51C基因突变2例（5.7%）,CHEK2,ATM,RAD50,MSH2,MRE11A和TP53基因突变各1例。BRCA1/2基因突变和高级别浆液性卵巢癌相关（P=0.034）,和家族史显著相关（P=0.003）,与年龄、FIGO分期无显著相关性（P>0.05）。另外,发现两种新的基因突变,包括BRCA1基因c.438delC和RAD51C基因c.390_391delAA。结论　BRCA1和BRCA2是卵巢癌最主要的胚系突变基因,该基因突变与遗传性卵巢癌显著相关。高通量基因测序技术可有效检测卵巢癌胚系易感基因的突变情况,为卵巢癌的早期诊断和预防提供科学依据。     

肿瘤相关ACTR基因多聚谷氨酰胺通道的编码序列多态性分析

目的：研究ACTR基因(甲状腺激素受体和视黄醛激活因子activator of retinoid and thyroid receptors，或称乳腺癌扩增基因)中多聚谷氨酰胺通道编码序列多态性与乳腺癌之间的关系。方法：107个DNA样本来自乳腺癌细胞系、原发性乳腺癌、BRCA1／BRCA2突变携带者外周血和正常对照人群外周血，应用PCR克隆／测序方法鉴别个体的每一种特异poly Q编码序列。结果：共发现23种特异的poly Q编码序列，肿瘤细胞系和原发性肿瘤组中拥有超过两个特异poly O编码序列的个体比例明显高于正常对照组人群；肿瘤细胞系和原发性肿瘤组中拥有罕见poly Q编码序列的个体比例亦明显高于正常对照组人群，原发性肿瘤组中拥有至少一个小于27个poly Q重复序列的个体比例明显高于BRCA1／BRCA2突变携带者组。结论：本结果提示ACTR基因的poly O编码序列的在体不稳定性可能作用于乳腺癌的致病过程。     

BRCA基因突变卵巢癌的治疗进展

卵巢癌是女性生殖系统肿瘤中最为致命的恶性肿瘤,大多在晚期被诊断出来,这在很大程度上导致了卵巢癌的预后不佳。乳腺癌易感基因(breast cancer susceptibility genes,BRCA)是一种重要的DNA同源修复基因,在正常的细胞DNA修复机制中起主要作用,其突变会导致同源重组缺陷,从而影响基因组的稳定...     

The retinoblastoma tumor suppressor modifies the therapeutic response of breast cancer

The retinoblastoma tumor suppressor (RB) protein is functionally inactivated in the majority of human cancers and is aberrant in one-third of all breast cancers. RB regulates G(1)/S-phase cell-cycle progression and is a critical mediator of antiproliferative signaling. Here the specific impact of RB deficiency on E2F-regulated gene expression, tumorigenic proliferation, and the response to 2 distinct lines of therapy was investigated in breast cancer cells. RB knockdown resulted in RB/E2F target gene deregulation and accelerated tumorigenic proliferation, thereby demonstrating that even in the context of a complex tumor cell genome, RB status exerts significant control over proliferation. Furthermore, the RB deficiency compromised the short-term cell-cycle inhibition following cisplatin, ionizing radiation, and antiestrogen therapy. In the context of DNA-damaging agents, this bypass resulted in increased sensitivity to these agents in cell culture and xenograft models. In contrast, the bypass of antiestrogen signaling resulted in continued proliferation and xenograft tumor growth in the presence of tamoxifen. These effects of aberrations in RB function were recapitulated by ectopic E2F expression, indicating that control of downstream target genes was an important determinant of the observed responses. Specific analyses of an RB gene expression signature in 60 human patients indicated that deregulation of this pathway was associated with early recurrence following tamoxifen monotherapy. Thus, because the RB pathway is a critical determinant of tumorigenic proliferation and differential therapeutic response, it may represent a critical basis for directing therapy in the treatment of breast cancer.     

Pharmacogenetics of anticancer drug sensitivity in pancreatic cancer

Chemotherapy has produced unsatisfactory results in pancreas cancer and novel approaches, including treatment tailoring by pharmacogenetic analysis and new molecular-targeted drugs, are required. The scarcity of effective therapies may reflect the lack of knowledge about the influence of tumor-related molecular abnormalities on responsiveness to drugs. Advances in the understanding of pancreas cancer biology have been made over the past decade, including the discovery of critical mutations in oncogenes (i.e., K-Ras) as well as the loss of tumor suppressor genes, such as TP53 and p16(INK4). Other studies showed the dysregulation of the expression of proteins involved in the control of cell cycle, proliferation, apoptosis, and invasiveness, such as Bcl-2, Akt, mdm2, and epidermal growth factor receptor. These characteristics might contribute to the aggressive behavior of pancreatic cancer and influence response to treatment. Indeed, the inactivation of p53 may explain the relative resistance to 5-fluorouracil, whereas Bcl-2 overexpression is associated with reduced sensitivity to gemcitabine. However, the future challenge of pancreas cancer chemotherapy relies on the identification of molecular markers that help in the selection of drugs best suited to the individual patient. Recent pharmacogenetic studies focused on genes encoding proteins directly involved in drug activity, showing the role of thymidylate synthase and human equilibrative nucleoside transporter-1 as prognostic factor in 5-fluorouracil- and gemcitabine-treated patients, respectively. Finally, inhibitors of signal transduction and angiogenesis are under extensive investigation, and several prospective trials have been devoted to this area. Pharmacogenetics is likely to play a central role in the personalization of treatment, to stratify patients based on their likelihood of response to both standard agents (i.e., gemcitabine/nucleoside transporters) and targeted treatments (i.e., epidermal growth factor receptor gene mutations and/or amplification and tyrosine kinase inhibitors), Thus, molecular analysis should be implemented in the optimal management of the patient affected by pancreatic adenocarcinoma.     

RCAS-mediated retroviral gene delivery: a versatile tool for the study of gene function in a mouse model of pancreatic cancer

Pancreatic cancer is one of the most common causes of cancer death in Western civilization and the 5-year survival rate is below 5%. To improve the prognosis of pancreatic cancer, there is the need to develop effective nonsurgical treatment options for the disease. In particular, in vivo models to validate potential targets at the genetic level are required. In this study we demonstrate that RCAS-mediated retroviral gene transfer into orthotopic pancreatic cancer tumor grafts is feasible. Furthermore, we show effective RCAS-dependent RNA interference in vivo. We validate in vivo bioluminescence imaging as a reliable tool to monitor tumor progression of orthotopic pancreatic cancer transplants longitudinally. In addition, we show that restoring expression of the tumor suppressor p53 by RCAS-mediated gene transfer and knockdown of the epidermal growth factor receptor by RCAS-dependent RNA interference impairs orthotopic pancreatic tumor growth in vivo. In conclusion, these data demonstrate that combining in vivo bioluminescence imaging with RCAS-mediated gene or short hairpin RNA transfer is a new model to investigate gene function in pancreatic cancer grafts and allows validation of potential new drug targets in vivo.     

The effect of endostatin and gemcitabine combined with HIFU on the animal xenograft model of human pancreatic cancer

Objective

To investigate the influence of the recombinant human endostatin and gemcitabine combined with HIFU on the mouse xenograft model of pancreatic cancer.

Methods

Use human pancreatic cancer cell line PANC-1 to set up the mouse xenograft model, then randomized into four arms. Each arm was treated with gemcitabine, endostatin, gemcitabine combined with endostatin and normal saline respectively. Observe the volume of the tumor, the serum VEGF level and MVD in the tumor tissue among the different arms. All mice were treated with HIFU, then pathological examination was done.

Results

The tumor volume, serum VEGF level and MVD in the combined-therapy arm are all lower than the monotherapy arms and the control arm. The coagulation necrosis occurred in tumors after HIFU treatment.

Conclusion

Endostatin and gemcitabine has better effect than gemcitabine or endostatin monotherapy on the animal xenograft model of human pancreatic cancer. HIFU combined with chemotherapy and/or targeted therapy may enhance the effect for pancreatic cancer.     

Long-Range PCR and Next-Generation Sequencing of BRCA1 and BRCA2 in Breast Cancer

Individuals and families carrying mutations in BRCA1 and BRCA2 (BRCA1/2) have a markedly elevated risk of developing breast and ovarian cancers. The first-generation of BRCA1/2 mutation analysis targeted only the coding exons and has implicated protein-truncating mutations (indel, nonsense) in BRCA1/2 inactivation. Recently, heritable breast cancers have also been attributed to other exonic mutations (missense, silent) and mutations in introns and untranslated regions. However, analysis of these alterations has been prohibitively laborious and cost intensive, and the proportion of cases carrying mutations in unscreened regions of BRCA1/2 and other predisposition genes is unknown. We have developed and validated a next-generation sequencing (NGS) approach for BRCA1/2 mutation analysis by applying long-range PCR and deep sequencing. Genomic DNA from familial breast cancer patients (N = 12) were screened and NGS successfully identified all 19 distinct (51 total) BRCA1 and 35 distinct (63 total) BRCA2 sequence alterations detectable by the Sanger sequencing, with no false-negative or positive results. In addition, we report the robust detection of variants from introns and untranslated regions. These results illustrate that NGS can provide comprehensive genetic information more quickly, accurately, and at a lower cost than conventional approaches, and we propose NGS to be a more effective method for BRCA1/2 mutational analysis. Advances in NGS will play an important role in enabling molecular diagnostics and personalized treatment of breast and ovarian cancers.     

Gene therapy based on gemcitabine chemosensitization suppresses pancreatic tumor growth.

Excepting surgical resection, there is no efficient treatment against pancreatic cancer. The chemotherapeutic agent gemcitabine improves the patient's clinical status but survival is not prolonged. The aim of this study was to design a new strategy to render gemcitabine more efficient in the treatment of pancreatic cancer using gene therapy. We have generated a fusion gene (DCK::UMK) combining deoxycytidine kinase (DCK) and uridine monophosphate kinase (UMK), which converts gemcitabine into its toxic phosphorylated metabolite. Antitumor effects of DCK::UMK gene expression were tested in vitro and in vivo in an orthotopic transplantable model of pancreatic cancer established in hamsters. DCK::UMK sensitizes pancreatic cancer cells to gemcitabine by reducing dramatically both in vitro cell viability and in vivo tumor volume. We found that in vivo expression of DCK::UMK resulted in an antitumor bystander effect due to apoptosis of untransduced cells. In vivo intratumoral gene transfer of DCK::UMK using the synthetic carrier PEI induced a potent tumor regression. Taken together, the results show that the fusion gene DCK::UMK sensitizes pancreatic cancer cells to gemcitabine treatment to induce cell death by apoptosis and tumor regression. Intratumoral delivery of the DCK::UMK gene in combination with gemcitabine might be of high interest for pancreatic cancer management.     

Tumor localization and biodistribution with radiolabeled monoclonal antibody against pancreatic cancer in tumor-bearing nude mice.

Nd2 is a murine monoclonal antibody produced against a mucin fraction purified from xenografts of a human pancreatic cancer cell line SW1990. Immunoperoxidase staining showed that the antigen recognized by Nd2 was present in 82.9% of pancreatic cancer tissues but not in tissues of normal pancreas and chronic pancreatitis. However Nd2 antigen was found not to be elevated in the sera of patients with pancreatic cancer. Four days after injection of 111In-Nd2 into athymic nude mice bearing SW1990 xenograft there was a higher accumulation in the tumor compared to 111In-normal mouse IgG1. When these mice were scanned with a gamma camera, labeled Nd2 was shown to accumulate in the tumor rapidly on the 1st day after injection and by the 4th day tumor accumulation was more distinctly visualized than non-specific accumulation in liver. These results indicate that Nd2 has high specificity and reactivity for pancreatic cancer and may have possible applicants in radioimmunodetection or targeting of therapeutic drugs in pancreatic cancer.