Mef Nilbert

A specific translocation, t(12;14)(q14–15; q23–24), characterizes a subgroup of uterine leiomyomas☆

We have cytogenetically investigated short-term cultures initiated from 34 uterine leiomyomas, all of which were histologically completely benign. Clonal chromosome abnormalities were detected in five cases, a normal female complement in 22, whereas, in the remaining seven tumors no karyotype could be established. Apparently identical reciprocal translocations, t(12;14)(q14-15;q23-24), were found as the sole abnormality in four tumors. The fifth abnormal case contained a t(2;14)(p11;p11). We conclude that chromosome aberrations may be found in myomas of the uterus, and that t(12;14)(q14-15;q23-24) characterizes a subset of these tumors.

The predictive value of KRAS, NRAS, BRAF, PIK3CA and PTEN for anti-EGFR treatment in metastatic colorectal cancer: A systematic review and meta-analysis

Abstract Background. In metastatic colorectal cancer, mutation testing for KRAS exon 2 is widely implemented to select patients with wild-type tumors for treatment with the monocloncal anti-EGFR antibodies cetuximab and panitumumab. The added predictive value of additional biomarkers in the RAS-RAF-MAPK and PI3K-AKT-mTOR pathways in colorectal cancer is uncertain, which led us to systematically review the impact of alterations in KRAS (outside of exon 2), NRAS, BRAF, PIK3CA and PTEN in relation to the clinical benefit from anti-EGFR treatment. Methods. In total, 22 studies that include 2395 patients formed the basis for a meta-analysis on alterations in KRAS exons 3 and 4, NRAS, BRAF, and PIK3CA and PTEN and outcome of anti-EGFR treatment. Odds ratios for objective response rate (ORR) and hazard ratios (HR) for progression-free survival (PFS) and overall survival (OS) were calculated. Results. Mutations in KRAS exons 3 and 4, BRAF, PIK3CA and non-functional PTEN (mutations or loss of protein expression) significantly predicted poor ORR (OR = 0.26, OR = 0.29, OR = 0.39, and OR = 0.41, respectively). Significantly shorter PFS applied to mutations in KRAS exons 3 and 4 (HR = 2.19), NRAS (HR = 2.30) and BRAF (HR = 2.95) and non-functional PTEN (HR = 1.88). Significantly shorter OS applied to mutations in KRAS exons 3 and 4 (HR = 1.78), NRAS (HR = 1.85), BRAF (HR = 2.52), PIK3CA (HR = 1.43) and alterations in PTEN (HR = 2.09). Conclusions. Meta-analysis suggests that mutations in KRAS exons 3 and 4, NRAS, BRAF and PIK3CA and non-functional PTEN predict resistance to anti-EGFR therapies and demonstrates that biomarker analysis beyond KRAS exon 2 should be implemented for prediction of clinical benefit from anti-EGFR antibodies in metastatic colorectal cancer.

Diagnostic and prognostic gene expression signatures in 177 soft tissue sarcomas: hypoxia-induced transcription profile signifies metastatic potential

BackgroundSoft tissue sarcoma (STS) diagnosis is challenging because of a multitude of histopathological subtypes, different genetic characteristics, and frequent intratumoral pleomorphism. One-third of STS metastasize and current risk-stratification is suboptimal, therefore, novel diagnostic and prognostic markers would be clinically valuable. We assessed the diagnostic and prognostic value of array-based gene expression profiles using 27 k cDNA microarrays in 177, mainly high-grade, STS of 13 histopathological subtypes.ResultsUnsupervised analysis resulted in two major clusters – one mainly containing STS characterized by type-specific genetic alterations and the other with a predominance of genetically complex and pleomorphic STS. Synovial sarcomas, myxoid/round-cell liposarcomas, and gastrointestinal stromal tumors clustered tightly within the former cluster and discriminatory signatures for these were characterized by developmental genes from the EGFR, FGFR, Wnt, Notch, Hedgehog, RAR and KIT signaling pathways. The more pleomorphic STS subtypes, e.g. leiomyosarcoma, malignant fibrous histiocytoma/undifferentiated pleomorphic sarcoma and dedifferentiated/pleomorphic liposarcoma, were part of the latter cluster and were characterized by relatively heterogeneous profiles, although subclusters herein were identified. A prognostic signature partly characterized by hypoxia-related genes was identified among 89 genetically complex pleomorphic primary STS and could, in a multivariate analysis including established prognostic markers, independently predict the risk of metastasis with a hazard ratio of 2.2 (P = 0.04).ConclusionDiagnostic gene expression profiles linking signaling pathways to the different STS subtypes were demonstrated and a hypoxia-induced metastatic profile was identified in the pleomorphic, high-grade STS. These findings verify diagnostic utility and application of expression data for improved selection of high-risk STS patients.

Involvement of adenomatous polyposis coli (APC)/β-catenin signalling in human breast cancer

We studied the relevance of adenomatous polyposis coli (APC)/beta-catenin signalling in the development of breast cancer by analysing the expression of beta-catenin in 54 primary breast tumours (34 ductal and 20 lobular). We showed that 13% of the tumours exhibited upregulated levels of beta-catenin in the cytosol suggesting that defects in APC/beta-catenin signalling components had lowered the rate of beta-catenin degradation. No mutations were observed in the amino-terminal region of beta-catenin, which comprises conserved serine residues important for phosphorylation-dependent degradation of the protein, but the APC protein was altered in 6% of the tumours. Tyrosine phosphorylation of beta-catenin was detected in only one tumour and could, therefore, not have been responsible for the observed increased levels of this protein. Although 9% of the tumours displayed upregulation of c-MYC protein, there was no correlation with beta-catenin overexpression, suggesting that increased beta-catenin expression is not the major cause of c-myc gene activation in breast cancer. It is imperative that elements that selectively drive the oncogenic activity of beta-catenin in breast cancer be identified.

Characteristic chromosome abnormalities, including rearrangements of 6p, del(7q), +12, and t(12;14), in 44 uterine leiomyomas

SummaryThe cytogenetic analysis of 224 leiomyomas from 138 patients is presented. An insufficient number of mitoses was found in 35 tumors, normal karyotypes in 145, and clonal chromosome aberrations were detected in 44. The three previously identified cytogenetic subgroups were all represented in this series: del(7) (q21.2q31.2) was found in 11, trisomy 12 in five, and t(12;14)(q14-15;q23-24) in one leiomyoma. Rearrangements of 6p, including deletions, inversions, and various translocations, were found in eight tumors, thus delineating a new cytogenetic subgroup of uterine leiomyoma. The remaining 21 karyotypically abnormal tumors had nonrecurrent changes. One leiomyoma had two cytogenetically unrelated clones characterized by del(7)(q21.2 q31.2) and +12. Karyotypic changes in two separate leiomyomas from the same uterus were identified in five patients; in three of them, different anomalies were found in the two tumors, whereas cytogenetically identical aberrations − del(7q) and dic(21;22) − were detected in two macroscopically discrete tumors. These findings suggest that whereas some multiple leiomyomas originate independently, others may be derived from the same neoplastic clone.

Characterization of the 12q13-15 amplicon in soft tissue tumors

Amplification of the genes MDM2, SAS, and CDK4, all located on the long arm of chromosome 12, has recently been demonstrated in human soft tissue tumors. To determine the extent of the amplification unit, we examined 16 soft tissue tumor samples, including pleomorphic liposarcoma, malignant fibrous histiocytoma (MFH), and atypical lipoma, by Southern blot analysis using 13 chromosome 12 probes. All tumors had previously been shown to have 3- to 20-fold amplification of MDM2. In five samples, all MFH, only MDM2 was amplified, whereas in the remaining 11 samples, two to five additional genes were amplified. The amplicon included markers both proximal and distal to MDM2, but was in all but one atypical lipoma confined to the chromosome region 12q13-15. Discontinuous amplicons were found in two of the tumors. This study indicates that MDM2, or possibly an as-yet-unidentified gene in its proximity, is the target gene of the 12q13-15 amplification in soft tissue tumors.

Pigmented villonodular synovitis: Monoclonality and metastasis—a case for neoplastic origin?

We report a 48-year follow-up of a case of recurrent pigmented villonodular synovitis of the knee. Subcutaneous metastasis to the contralateral thigh was an unusual finding. Histology demonstrated fibroblastic and histiocytic proliferation, as well as increased mitotic activity in recurrent lesions. Cytogenetic analyses demonstrated monoclonality and chromosomal abnormalities. Our findings support a neoplastic origin of this lesion.

Microsatellite instability and expression of MLH1 and MSH2 in carcinomas of the small intestine

Carcinomas of the small intestine are rare, but the risk is greatly increased in patients with hereditary nonpolyposis colorectal cancer (HNPCC) due to an inherited mismatch repair (MMR) gene mutation, most commonly affecting the genes MLH1 or MSH2. Defective MMR is characterized by microsatellite instability (MSI) and loss of MMR protein expression in the tumor tissue. However, a subset of several sporadic tumor types, including about 15% of colon cancers, also evolve through defective MMR.

Evaluation of the tissue microarray technique for immunohistochemical analysis in rectal cancer.

BACKGROUND Immunohistochemical staining for tumor-associated proteins is widely used for the identification of novel prognostic markers. Recently, a tissue-conserving, high-throughput technique, tissue microarray, has been introduced. This technique uses 0.6-mm tissue core biopsy specimens, 500 to 1000 of which are brought into a new paraffin array block, which can be sectioned up to 100 times. METHODS We evaluated the tissue microarray technique for immunohistochemical analysis in 20 rectal cancers. Immunohistochemical staining was performed for the proliferation marker Ki-67 and the tumor suppressor protein p53 in whole tissue sections and in tissue core biopsy specimens. RESULTS The whole tissue sections were assessed by counting all cells in 10 high-power fields (x40), which resulted in a mean fraction of Ki-67-expressing tumor cells of 0.81 (range, 0.54-1.0). p53 expression assessed in whole tissue sections showed nuclear staining in 15 (75%) of 20 rectal carcinomas. For the tissue microarray technique, a median of 3 (range, 3-5) 0.6-mm tissue core biopsy specimens were studied from each of the 20 tumor specimens. The tissue microarray method gave a mean Ki-67 expression of 0.85 (range, 0.50-1.0) in tumor cell nuclei and showed p53 protein expression in the same 15 of 20 tumors as in the whole tissue sections. CONCLUSION We conclude that the tissue microarray technique for immunohistochemical staining in rectal cancer yields staining of good quality and expression data for Ki-67 and p53 comparable to those obtained with whole tissue staining. The feasibility of tissue microarray thus enables time- and tissue-preserving studies of multiple markers in large tumor series.

Ovarian cancer linked to Lynch syndrome typically presents as early-onset, non-serous epithelial tumors.

OBJECTIVE Heredity is a major cause of ovarian cancer and during recent years the contribution from germline mismatch repair (MMR) gene mutations linked to Lynch syndrome has gradually been recognized. METHODS We characterized clinical features, tumor morphology and mismatch repair defects in all ovarian cancers identified in Swedish and Danish Lynch syndrome families. RESULTS In total, 63 epithelial ovarian cancers developed at mean 48 (range 30-79) years of age with 47% being early stage (FIGO stage I). Histologically, endometrioid (35%) and clear cell (17%) tumors were overrepresented. The underlying MMR gene mutations in these families affected MSH2 in 49%, MSH6 in 33% and MLH1 in 17%. Immunohistochemical loss of the corresponding MMR protein was demonstrated in 33/36 (92%) tumors analyzed. CONCLUSION The combined data from our cohorts demonstrate that ovarian cancer associated with Lynch syndrome typically presents at young age as early-stage, non-serous tumors, which implicates that a family history of colorectal and endometrial cancer should be specifically considered in such cases.