Synnöve Staff

Mutations in BRIP1 confer high risk of ovarian cancer

Ovarian cancer causes more deaths than any other gynecologic malignancy in developed countries. Sixteen million sequence variants, identified through whole-genome sequencing of 457 Icelanders, were imputed to 41,675 Icelanders genotyped using SNP chips, as well as to their relatives. Sequence variants were tested for association with ovarian cancer (N of affected individuals = 656). We discovered a rare (0.41% allelic frequency) frameshift mutation, c.2040_2041insTT, in the BRIP1 (FANCJ) gene that confers an increase in ovarian cancer risk (odds ratio (OR) = 8.13, P = 2.8 × 10−14). The mutation was also associated with increased risk of cancer in general and reduced lifespan by 3.6 years. In a Spanish population, another frameshift mutation in BRIP1, c.1702_1703del, was seen in 2 out of 144 subjects with ovarian cancer and 1 out of 1,780 control subjects (P = 0.016). This allele was also associated with breast cancer (seen in 6/927 cases; P = 0.0079). Ovarian tumors from heterozygous carriers of the Icelandic mutation show loss of the wild-type allele, indicating that BRIP1 behaves like a classical tumor suppressor gene in ovarian cancer.

Multiple molecular mechanisms underlying trastuzumab and lapatinib resistance in JIMT-1 breast cancer cells

Trastuzumab plays an important role in breast cancer therapy. However, a significant fraction of patients do not respond to therapy or they tend to develop resistance shortly after beginning therapy. Although some resistance mechanisms have been described, it is unclear whether these mechanisms can coexist. In this study, we analyzed the resistance mechanisms in the breast cancer cell line JIMT-1, a model of intrinsic trastuzumab resistance. We compared the JIMT-1 cell line with a panel of eight HER-2 positive breast cancer cell lines. All cell lines were characterized for the phosphatidylinositol 3-kinase (PIK3CA) mutation status, expression levels of the phosphatase and tensin homolog on chromosome 10 (PTEN) and neuregulin-1 (NRG1) mRNA, HER-2 gene copy number, and protein expression. The results were correlated to the sensitivity to trastuzumab and lapatinib as well as the potency of trastuzumab-mediated antibody-dependent cellular cytotoxicity (ADCC) evoked by trastuzumab. JIMT-1 cells showed several co-existing drug resistance mechanisms, including an activating mutation of the PIK3CA gene, low expression of PTEN, high expression of NRG1, and relatively low expression of HER-2 receptor protein (despite gene amplification). All these features were present at variable levels in other cell lines, whereas JIMT-1 was unique in displaying all these factors at the same time. Unexpectedly, ADCC reaction by normal lymphocytes was equally strong in all HER-2 positive cell lines, without any correlation to molecular markers or direct sensitivity to the drugs. Resistance to trastuzumab and lapatinib is probably caused by several co-existing molecular mechanisms. Direct sensitivity to trastuzumab and lapatinib was not correlated with ADCC.

Characterization of a Novel Breast Carcinoma Xenograft and Cell Line Derived from a BRCA1 Germ-Line Mutation Carrier

A human tumor xenograft (L56Br-X1) was established from a breast cancer axillary lymph node metastasis of a 53-year-old woman with a BRCA1 germ-line nonsense mutation (1806C>T; Q563X), and a cell line (L56Br-C1) was subsequently derived from the xenograft. The xenograft carries only the mutant BRCA1 allele and expresses mutant BRCA1 mRNA but no BRCA1 protein as determined by immunoprecipitation or Western blotting. The primary tumor, lymph node metastasis, and xenograft were hypodiploid by DNA flow cytometry, whereas the cell line displayed an aneuploidy apparently developed via polyploidization. Cytogenetic analysis, spectral karyotyping, and comparative genomic hybridization of the cell line revealed a highly complex karyotype with numerous unbalanced translocations. The xenograft and cell line had retained a somatic TP53 missense mutation (S215I) originating from the primary tumors, as well as a lack of immunohistochemically detectable expression of steroid hormone receptors, epidermal growth factor receptor, human epidermal growth factor receptor 2 (HER-2), and keratin 8. Global gene expression analysis by cDNA microarrays supported a correlation between the expression profiles of the primary tumor, lymph node metastasis, xenograft, and cell line. We conclude that L56Br-X1 and L56Br-C1 are useful model systems for studies of the pathogenesis and new therapeutic modalities of BRCA1-induced human breast cancer.

Aurora-A overexpression and aneuploidy predict poor outcome in serous ovarian carcinoma

OBJECTIVE Aurora-A is a potential oncogene and therapeutic target in ovarian carcinoma. It is involved in mitotic events and overexpression leads to centrosome amplification and chromosomal instability. The objective of this study was to evaluate the clinical significance of Aurora-A and DNA ploidy in serous ovarian carcinoma. METHODS Serous ovarian carcinomas were analysed for Aurora-A protein by immunohistochemistry (n=592), Aurora-A copy number by CISH (n=169), Aurora-A mRNA by real-time PCR (n=158) and DNA ploidy by flowcytometry (n=440). RESULTS Overexpression of Aurora-A was found in 27% of the tumors, cytoplasmic overexpression in 11% and nuclear in 17%. The cytoplasmic and nuclear overexpression were nearly mutually exclusive. Both cytoplasmic and nuclear overexpression were associated with shorter survival, high grade, high proliferation index and aberrant p53. Interestingly, only cytoplasmic expression was associated with aneuploidy and expression of phosphorylated Aurora-A. DNA ploidy was associated with poor patient outcome as well as aggressive clinicopathological parameters. In multivariate analysis, Aurora-A overexpression appeared as an independent prognostic factor for disease-free survival, together with grade, stage and ploidy. CONCLUSIONS Aurora-A protein expression is strongly linked with poor patient outcome and aggressive disease characteristics, which makes Aurora-A a promising biomarker and a potential therapeutic target in ovarian carcinoma. Cytoplasmic and nuclear Aurora-A protein may have different functions. DNA aneuploidy is a strong predictor of poor prognosis in serous ovarian carcinoma.

Preservation of nucleic acids and tissue morphology in paraffin-embedded clinical samples: comparison of five molecular fixatives

Formalin fixation preserves tissue morphology at the expense of macromolecule integrity. Freshly frozen samples are the golden standard for DNA and RNA analyses but require laborious deep-freezing and frozen sectioning for morphological studies. Alternative tissue stabilisation methods are therefore needed. We analysed the preservation of nucleic acids, immunohistochemical staining properties and tissue morphology in paraffin-embedded clinical tissue samples fixed with Z7, RCL2, PAXgene, Allprotect and RNAlater. Formalin-fixed and deep-frozen samples were used as controls. Immunohistochemical analyses showed good preservation of antigenicity in all except Allprotect and RNAlater-fixed samples. RNA quality, based on RNA integrity number value by Bioanalyzer, was comparable with freshly frozen samples only in PAXgene-fixed samples. According to quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analyses, RNA from PAXgene samples yielded results similar to freshly frozen samples. No difference between fixatives was seen in DNA analyses (PCR and real-time PCR). In conclusion, PAXgene seems to be superior to other molecular fixatives and formaldehyde.

Multiple copies of mutant BRCA1 and BRCA2 alleles in breast tumors from germ‐line mutation carriers

Inactivation of the BRCA1 and BRCA2 breast cancer susceptibility genes has been reported to occur via a germ‐line mutation of one allele and a somatic loss of the remaining wild‐type allele. We investigated the genetic mechanisms behind the second event in breast tumors from 17 BRCA1 and eight BRCA2 germ‐line mutation carriers, as compared with 21 sporadic breast tumors. Microsatellite markers intragenic or in close proximity to both genes were used to analyze imbalances between the mutant and wild‐type alleles. The actual and relative gene copy numbers were scored by fluorescence in situ hybridization (FISH) analysis of tumor cells using locus and centromere specific probes. All but one of the informative BRCA1 and BRCA2 tumors exhibited allelic imbalance and loss of the corresponding wild type allele. In contrast to sporadic tumors, however, where allelic imbalance at the BRCA1 and BRCA2 loci correlated well with relative copy number losses by FISH, a simple reduction to a single copy (average copy number ratio 2:1) was found in only two BRCA1 (12%) and four BRCA2 (50%) tumors. The majority of BRCA1 and BRCA2 tumors showed a copy number reduction (relative to reference probe with ratios 4:2, 3:2, 4:3) at corresponding loci, suggesting that a specific physical deletion of the wild‐type BRCA gene allele has been followed by a duplication of the remaining mutant allele via polyploidization. Several tumors contained multiple copies of BRCA1 and BRCA2 genes without relative copy number changes, implying that loss of wild‐type alleles is executed by alternative mechanisms such as mitotic recombination, non‐disjunctional chromosomal loss with or without reduplication, or by gene conversion. A paradoxical relative copy number gain of the mutant allele was evident in three BRCA1 tumors (18%), which could be of biological relevance if a dominant negative or gain‐of‐function model was ascribed for certain BRCA1 mutants. Our results indicate that complex genetic alterations are operational at the BRCA1 and BRCA2 loci in tumors from genetically predisposed individuals. Genes Chromosomes Cancer 28:432–442, 2000.

Epigenetic analysis of sporadic and Lynch-associated ovarian cancers reveals histology-specific patterns of DNA methylation

Diagnosis and treatment of epithelial ovarian cancer is challenging due to the poor understanding of the pathogenesis of the disease. Our aim was to investigate epigenetic mechanisms in ovarian tumorigenesis and, especially, whether tumors with different histological subtypes or hereditary background (Lynch syndrome) exhibit differential susceptibility to epigenetic inactivation of growth regulatory genes. Gene candidates for epigenetic regulation were identified from the literature and by expression profiling of ovarian and endometrial cancer cell lines treated with demethylating agents. Thirteen genes were chosen for methylation-specific multiplex ligation-dependent probe amplification assays on 104 (85 sporadic and 19 Lynch syndrome-associated) ovarian carcinomas. Increased methylation (i.e., hypermethylation) of variable degree was characteristic of ovarian carcinomas relative to the corresponding normal tissues, and hypermethylation was consistently more prominent in non-serous than serous tumors for individual genes and gene sets investigated. Lynch syndrome-associated clear cell carcinomas showed the highest frequencies of hypermethylation. Among endometrioid ovarian carcinomas, lower levels of promoter methylation of RSK4, SPARC, and HOXA9 were significantly associated with higher tumor grade; thus, the methylation patterns showed a shift to the direction of high-grade serous tumors. In conclusion, we provide evidence of a frequent epigenetic inactivation of RSK4, SPARC, PROM1, HOXA10, HOXA9, WT1-AS, SFRP2, SFRP5, OPCML, and MIR34B in the development of non-serous ovarian carcinomas of Lynch and sporadic origin, as compared to serous tumors. Our findings shed light on the role of epigenetic mechanisms in ovarian tumorigenesis and identify potential targets for translational applications.

Frequent somatic loss of BRCA1 in breast tumours from BRCA2 germ-line mutation carriers and vice versa.

Breast cancer susceptibility genes BRCA1 and BRCA2 are tumour suppressor genes the alleles of which have to be inactivated before tumour development occurs. Hereditary breast cancers linked to germ-line mutations of BRCA1 and BRCA2 genes almost invariably show allelic imbalance (AI) at the respective loci. BRCA1 and BRCA2 are believed to take part in a common pathway in maintenance of genomic integrity in cells. We carried out AI and fluorescence in situ hybridization (FISH) analyses of BRCA2 in breast tumours from germ-line BRCA1 mutation carriers and vice versa. For comparison, 14 sporadic breast tumours were also studied. 8 of the 11 (73%) informative BRCA1 mutation tumours showed AI at the BRCA2 locus. 53% of these tumours showed a copy number loss of the BRCA2 gene by FISH. 5 of the 6 (83%) informative BRCA2 mutation tumours showed AI at the BRCA1 locus. Half of the tumours (4/8) showed a physical deletion of the BRCA1 gene by FISH. Combined allelic loss of both BRCA1 and BRCA2 gene was seen in 12 of the 17 (71%) informative hereditary tumours, whereas copy number losses of both BRCA genes was seen in only 4/14 (29%) sporadic control tumours studied by FISH. In conclusion, the high prevalence of AI at BRCA1 in BRCA2 mutation tumours and vice versa suggests that somatic events occurring at the other breast cancer susceptibility gene locus may be selected in the cancer development. The mechanism resulting in AI at these loci seems more complex than a physical deletion.

Acute digital ischemia complicating gemcitabine and carboplatin combination chemotherapy for ovarian cancer.

Sir, We would like to bring to attention a case of a 57-year-old woman, who underwent exploratory laparotomy, total abdominal hysterectomy, bilateral salpingo-oophorectomy and omentectomy for stage IIIC serous ovarian adenocarcinoma. Debulking was suboptimal. Her medical history included medically treated hypercholesterolemia. A right-sided carpal tunnel syndrome (CTS) had been operated on a few years before and the mildly symptomatic left-sided CTS was treated conservatively. There was no previous history of thrombotic events. After first-line standard combination chemotherapy turned out ineffective, second-line combination chemotherapy with gemcitabine and carboplatin was started. During its fifth cycle the patient complained of numbness, swelling and occasional cyanosis of digits II, III and IV of the left hand. During follow-up the digits became painful, cyanosis progressed, and hand surgery consultation was obtained. Aceto-salicylic acid (ASA), 100 mg per day, and the calcium channel blocker felodipine 5 mg per day were started. A selective left hand arteriogram showed a combination of occlusion of both ulnar and II-IV digital arteries (Figure 1). With conservative treatment digital cyanosis started slowly to alleviate. During follow-up the patient developed also deep venous thrombosis (DVT) in a lower extremity. The DVT was treated with subcutaneous low molecular weight heparin, i.e. enoxaparin 1 mg/kg twice daily. Initiation of the enoxaparin treatment for DVT associated with marked clinical improvement of the digital cyanosis. To our knowledge, this is the first report describing gemcitabineassociated digital ischemia in an ovarian cancer patient. Some reports have described digital ischemia as a paraneoplastic phenomenon in metastatic ovarian cancer (1). As a paraneoplastic phenomenon, digital ischemia often manifests bilaterally and responds more likely to anti-cancer than anti-thrombotic therapy. In addition to common side effects such as myelosuppression and skin rash, gemcitabine therapy for ovarian cancer has been associated with certain severe complications such as pulmonary toxicity and hemolytic uremic syndrome, while vascular side-effects may have been underrated (2,3). In other cancers, gemcitabine therapy, especially in combination with carboplatin, has been associated with various vascular complications, such as acute arterial digital ischemia with necrosis, thrombotic microangiopathy, vasculitis, systemic capillary leak and reversible posterior leukoencephalopathy syndromes (4). Our patient had unoperated CTS in the affected hand possibly compromising local arterial microcirculation. In addition, the patient had hypercholesterolemia as a risk factor for peripheral atherosclerosis. These factors, in theory, may have predisposed our patient to acute vascular side effects induced by gemcitabine during combination chemotherapy. Gemcitabine therapy should be administered with caution to ovarian cancer patients carrying any Figure 1. Filling defects in ulnar and II-IV digital arteries are shown in the arteriogram of patient’s left arm. A total occlusion of ulnar artery at the wrist level is indicated by an arrow and a total filling defect in the third digit is indicated by an asterisk.

L1 Cell Adhesion Molecule as a Predictor of Disease-Specific Survival and Patterns of Relapse in Endometrial Cancer.

OBJECTIVE The aim was to study the association of L1 cell adhesion molecule (L1CAM) expression with the outcome of patients with endometrial cancer, especially with regard to conventional risk variables, and to compare the patterns of relapse in L1CAM-positive and -negative cancers. METHODS This was a retrospective study of 805 women. The Kaplan-Meier method and univariate and multivariate Cox regression models were applied for survival analyses. Missing data were replaced using multiple imputation. The median follow-up time was 51 months (range, 1-98). RESULTS One hundred twenty-one (15.0%) cases were L1CAM positive. L1CAM positivity was associated with high stage (I vs II-IV) (odds ratio [OR], 2.3), lymph node involvement (OR, 2.9), poor differentiation (OR, 6.1), non-endometrioid histology (OR, 9.9), lymphovascular space invasion (OR, 2.8), cervical stromal invasion (OR, 1.8), positive peritoneal cytology (OR, 4.1), and age older than 65 years (OR, 2.8). The frequencies of deep myometrial invasion (50% or deeper), tumor size 2 cm or greater, and body mass index 30 kg/m2 or greater were not significantly different between L1CAM-positive and -negative cases. L1CAM predicted poor disease-specific survival in endometrioid (P < 0.0001) but not in non-endometrioid carcinomas (P = 0.934). The negative impact of L1CAM on outcome was confirmed in a Cox multivariate disease-specific survival analysis. Univariate survival analyses in the different ESMO-ESGO-ESTRO endometrial cancer risk groups showed an association between L1CAM positivity and poor outcome in intermediate (hazard ratio, 12) and high-risk advanced metastatic (hazard ratio, 2.0) groups. Extra-abdominal relapses were more frequent in L1CAM-positive (13.2%) than L1CAM-negative (1.9%) stage I endometrioid carcinomas (P < 0.0001), whereas other site-specific relapses in local cancers were L1CAM independent. CONCLUSIONS L1CAM is associated with the occurrence of poor prognostic variables and predicts advanced disease in endometrial cancer. L1CAM predicts extra-abdominal relapses and poor survival in endometrioid endometrial cancer, but seems not to be a prognostic factor in non-endometrioid carcinomas.Objective The aim was to study the association of L1 cell adhesion molecule (L1CAM) expression with the outcome of patients with endometrial cancer, especially with regard to conventional risk variables, and to compare the patterns of relapse in L1CAM-positive and -negative cancers. Methods This was a retrospective study of 805 women. The Kaplan–Meier method and univariate and multivariate Cox regression models were applied for survival analyses. Missing data were replaced using multiple imputation. The median follow-up time was 51 months (range, 1–98). Results One hundred twenty-one (15.0%) cases were L1CAM positive. L1CAM positivity was associated with high stage (I vs II–IV) (odds ratio [OR], 2.3), lymph node involvement (OR, 2.9), poor differentiation (OR, 6.1), non-endometrioid histology (OR, 9.9), lymphovascular space invasion (OR, 2.8), cervical stromal invasion (OR, 1.8), positive peritoneal cytology (OR, 4.1), and age older than 65 years (OR, 2.8). The frequencies of deep myometrial invasion (50% or deeper), tumor size 2 cm or greater, and body mass index 30 kg/m2 or greater were not significantly different between L1CAM-positive and -negative cases. L1CAM predicted poor disease-specific survival in endometrioid (P < 0.0001) but not in non-endometrioid carcinomas (P = 0.934). The negative impact of L1CAM on outcome was confirmed in a Cox multivariate disease-specific survival analysis. Univariate survival analyses in the different ESMO–ESGO–ESTRO endometrial cancer risk groups showed an association between L1CAM positivity and poor outcome in intermediate (hazard ratio, 12) and high-risk advanced metastatic (hazard ratio, 2.0) groups. Extra-abdominal relapses were more frequent in L1CAM-positive (13.2%) than L1CAM-negative (1.9%) stage I endometrioid carcinomas (P < 0.0001), whereas other site-specific relapses in local cancers were L1CAM independent. Conclusions L1CAM is associated with the occurrence of poor prognostic variables and predicts advanced disease in endometrial cancer. L1CAM predicts extra-abdominal relapses and poor survival in endometrioid endometrial cancer, but seems not to be a prognostic factor in non-endometrioid carcinomas.