Valérie Velasco

MED12 Alterations in Both Human Benign and Malignant Uterine Soft Tissue Tumors

The relationship between benign uterine leiomyomas and their malignant counterparts, i.e. leiomyosarcomas and smooth muscle tumors of uncertain malignant potential (STUMP), is still poorly understood. The idea that a leiomyosarcoma could derive from a leiomyoma is still controversial. Recently MED12 mutations have been reported in uterine leiomyomas. In this study we asked whether such mutations could also be involved in leiomyosarcomas and STUMP oncogenesis. For this purpose we examined 33 uterine mesenchymal tumors by sequencing the hot-spot mutation region of MED12. We determined that MED12 is altered in 66.6% of typical leiomyomas as previously reported but also in 11% of STUMP and 20% of leiomyosarcomas. The mutated allele is predominantly expressed in leiomyomas and STUMP. Interestingly all classical leiomyomas exhibit MED12 protein expression while 40% of atypical leiomyomas, 50% of STUMP and 80% of leiomyosarcomas (among them the two mutated ones) do not express MED12. All these tumors without protein expression exhibit complex genomic profiles. No mutations and no expression loss were identified in an additional series of 38 non-uterine leiomyosarcomas. MED12 mutations are not exclusive to leiomyomas but seem to be specific to uterine malignancies. A previous study has suggested that MED12 mutations in leiomyomas could lead to Wnt/β-catenin pathway activation however our immunohistochemistry results show that there is no association between MED12 status and β-catenin nuclear/cytoplasmic localization. Collectively, our results show that subgroups of benign and malignant tumors share a common genetics. We propose here that MED12 alterations could be implicated in the development of smooth muscle tumor and that its expression could be inhibited in malignant tumors.

Molecular apocrine differentiation is a common feature of breast cancer in patients with germline PTEN mutations

IntroductionBreast carcinoma is the main malignant tumor occurring in patients with Cowden disease, a cancer-prone syndrome caused by germline mutation of the tumor suppressor gene PTEN characterized by the occurrence throughout life of hyperplastic, hamartomatous and malignant growths affecting various organs. The absence of known histological features for breast cancer arising in a PTEN-mutant background prompted us to explore them for potential new markers.MethodsWe first performed a microarray study of three tumors from patients with Cowden disease in the context of a transcriptomic study of 74 familial breast cancers. A subsequent histological and immunohistochemical study including 12 additional cases of Cowden disease breast carcinomas was performed to confirm the microarray data.ResultsUnsupervised clustering of the 74 familial tumors followed the intrinsic gene classification of breast cancer except for a group of five tumors that included the three Cowden tumors. The gene expression profile of the Cowden tumors shows considerable overlap with that of a breast cancer subgroup known as molecular apocrine breast carcinoma, which is suspected to have increased androgenic signaling and shows frequent ERBB2 amplification in sporadic tumors. The histological and immunohistochemical study showed that several cases had apocrine histological features and expressed GGT1, which is a potential new marker for apocrine breast carcinoma.ConclusionsThese data suggest that activation of the ERBB2-PI3K-AKT pathway by loss of PTEN at early stages of tumorigenesis promotes the formation of breast tumors with apocrine features.

YWHAE rearrangement identified by FISH and RT-PCR in endometrial stromal sarcomas: genetic and pathological correlations

Endometrial stromal sarcomas represent the second most common mesenchymal uterine tumor. The 2003 WHO classification distinguishes low-grade and undifferentiated endometrial stromal sarcomas with different prognoses. Endometrial stromal sarcomas are a genetically heterogeneous group of sarcomas harboring different cytogenetic anomalies. Recently, a fusion between the YWHAE and FAM22A/B genes subsequent to a t(10;17) (q22;p13) has been described in endometrial sarcomas with high-grade histology. We examined YWHAE rearrangements by FISH break-apart and RT-PCR in a series of 27 undifferentiated uterine stromal sarcoma without JAZF1 rearrangements. Immunohistochemistry (IHC) was carried out with a panel of antibodies (estrogen (ER) and progesterone (PR) receptors, CD10, Cyclin D1, β-catenin, p53, and Ki-67). We identified a subgroup of endometrial sarcomas with high-grade histology and uniform morphology harboring YWHAE rearrangements. FISH break-apart was interpretable in 20 cases (74%). Twelve cases (60%) showed <10% of tumor cells with a YWHAE rearrangement, 4 cases (20%) showed between 10 and ≤20%, and 4 (20%) >20%. RT-PCR was tested on 24/27 cases (88%) and 19 cases were interpretable (79%). Five cases (26%) showed a specific fusion transcript YWHAE–FAM22A/B sequence. The best concordance rate between FISH and RT-PCR (94%) was obtained with the threshold of 20% of cells with a YWHAE rearrangement. The YWHAE-rearranged cases showed high-grade morphology with uniform appearance, spindle or round epithelioid cells, low ER and PR, CD10 expression, and a high and diffuse positivity for Cyclin D1, p53, and nuclear β-catenin negativity. Cyclin D1 was the most sensitive marker for high-grade endometrial sarcomas with YWHAE rearrangement. All undifferentiated uterine sarcomas with pleomorphic appearances did not harbor any YWHAE rearrangements, except for one case. Overall, for endometrial sarcoma cases with high-grade morphology we recommend to test for YWHAE rearrangements by FISH break-apart, a cost- and time-efficient method, and to complete the investigation by RT-PCR in borderline cases.

Transgelin is a novel marker of smooth muscle differentiation that improves diagnostic accuracy of leiomyosarcomas: a comparative immunohistochemical reappraisal of myogenic markers in 900 soft tissue tumors.

Immunohistochemical use of myogenic markers serves to define smooth or skeletal muscle differentiation in soft tissue tumors. Establishing smooth muscle differentiation in malignant lesions can be challenging in some cases. We immunohistochemically examined 900 soft tissue tumors selected from the French Sarcoma Group’s archived tissue collection, which contains a large number of leiomyosarcomas. The four most widely used smooth muscle diagnostic markers were evaluated (smooth muscle actin, desmin, h-caldesmon and calponin), and compared with a novel marker, transgelin. The diagnostic performance of each marker was statistically assessed in terms of sensitivity (Se), specificity (Sp), positive predictive value (PPV), negative predictive value (NPV) and accuracy (A), in leiomyosarcomas versus all other sarcomas including gastrointestinal stromal tumors (GIST), and second in leiomyosarcomas versus specific tumor types. In leiomyosarcomas versus all other sarcomas including GIST, transgelin emerged as the best diagnostic marker (Se: 83%, Sp: 82%, PPV: 67%, NPV: 92%, A: 83%), compared with smooth muscle actin (Se: 75%, Sp: 83, PPV: 66%, NPV: 89%, A: 81%), desmin (Se: 45%, Sp: 88%, PPV: 62%, NPV: 79%, A: 75%), h-caldesmon (Se: 50%, Sp: 90%, PPV: 67%, NPV: 81%, A: 78%) and calponin (Se: 76%, Sp: 70, PPV: 52%, NPV: 87%, A: 71%). In leiomyosarcomas compared with other specific tumor types such as undifferentiated pleomorphic sarcoma and myxofibrosarcoma, the accuracy for transgelin varied from 80 to 87% whereas it was lower for all other markers (between 51 and 80%). These results indicate that transgelin could be used in practice as an additional marker useful for decision making, especially in those tumors with incomplete immunophenotypes.

Accumulation of an endogenous tryptophan-derived metabolite in colorectal and breast cancers.

Tumor immune escape mechanisms are being regarded as suitable targets for tumor therapy. Among these, tryptophan catabolism plays a central role in creating an immunosuppressive environment, leading to tolerance to potentially immunogenic tumor antigens. Tryptophan catabolism is initiated by either indoleamine 2,3-dioxygenase (IDO-1/-2) or tryptophan 2,3-dioxygenase 2 (TDO2), resulting in biostatic tryptophan starvation and l-kynurenine production, which participates in shaping the dynamic relationship of the host’s immune system with tumor cells. Current immunotherapy strategies include blockade of IDO-1/-2 or TDO2, to restore efficient antitumor responses. Patients who might benefit from this approach are currently identified based on expression analyses of IDO-1/-2 or TDO2 in tumor tissue and/or enzymatic activity assessed by kynurenine/tryptophan ratios in the serum. We developed a monoclonal antibody targeting l-kynurenine as an in situ biomarker of IDO-1/-2 or TDO2 activity. Using Tissue Micro Array technology and immunostaining, colorectal and breast cancer patients were phenotyped based on l-kynurenine production. In colorectal cancer l-kynurenine was not unequivocally associated with IDO-1 expression, suggesting that the mere expression of tryptophan catabolic enzymes is not sufficiently informative for optimal immunotherapy.

The mammary ducts create a favourable microenvironment for xenografting of luminal and molecular apocrine breast tumours

There is a paucity of models for hormone receptor‐positive (HR+) breast cancer because of the difficulty of establishing xenografts from these tumours. We show that this obstacle can be overcome by injecting human tumour cells directly into the mammary ducts of immunodeficient mice. Tumours from 31 patients were infected overnight with a lentiviral vector expressing tdTomato and injected through the nipple into the mammary ducts of NOD‐SCID‐IL2RG−/− mice. Tumours formed in the mice in 77% of cases after the first injection (6/8 luminal A, 15/20 luminal B, and 3/3 molecular apocrine). Four luminal A and one molecular apocrine graft were tested in secondary and tertiary grafts: all were successfully passaged in secondary and 4/5 in tertiary grafts. None of the samples engrafted when injected subcutaneously. The morphology, oestrogen receptor (ER), progesterone receptor (PR), androgen receptor (AR), and Ki‐67 profiles of the clinical samples were maintained in the tertiary grafts. We also show that the intraductal approach can be used to test the response to targeted therapy with fulvestrant and palbociclib, using a genetically defined ER+ model. We conclude that the mammary ducts create a microenvironment that is uniquely favourable to the survival and growth of tumours derived from mammary hormone‐sensing cells. This approach opens the door to testing genomically targeted treatment of HR+ tumours in precision medicine programmes. Copyright

Uterine Tumor Resembling Ovarian Sex Cord Tumor (UTROSCT) Commonly Exhibits Positivity With Sex Cord Markers FOXL2 and SF-1 but Lacks FOXL2 and DICER1 Mutations.

Uterine tumor resembling ovarian sex cord tumor (UTROSCT) is a rare neoplasm which morphologically and immunohistochemically exhibits overlap with an ovarian sex cord tumor. Although many of these neoplasms are positive with markers of ovarian sex cord-stromal tumors, staining is often limited and the pathogenesis of UTROSCT is unknown. To further explore the sex cord lineage of UTROSCT, we studied 19 of these neoplasms and examined the expression of 2 recently described markers of ovarian sex cord-stromal tumors, FOXL2, and steroidogenic factor-1. We also undertook FOXL2 and DICER1 mutation analysis in these cases; a somatic missense mutation in codon C134W (402C→G) of FOXL2 gene has been demonstrated in the vast majority (>95%) of ovarian adult granulosa cell tumors and somatic DICER1 mutations are found in approximately 60% of ovarian Sertoli-Leydig cell tumors. Ten of 19 cases (53%) exhibited nuclear immunoreactivity with FOXL2 and 11 of 19 (58%) exhibited nuclear staining with steroidogenic factor-1. Neither FOXL2 nor DICER1 mutations were identified in any case where there was sufficient tumor tissue for analysis (18 and 9 cases, respectively). Despite exhibiting an immunophenotype characteristic of a sex cord-stromal tumor, mutations in FOXL2 and DICER1, the 2 most common mutations hitherto reported in ovarian sex cord-stromal tumors, are not a feature of UTROSCT.

Smooth muscle differentiation identifies two classes of poorly differentiated pleomorphic sarcomas with distinct outcome

The clinical relevance of accurately diagnosing pleomorphic sarcomas has been shown, especially in cases of undifferentiated pleomorphic sarcomas with myogenic differentiation, which appear significantly more aggressive. To establish a new smooth muscle differentiation classification and to test its prognostic value, 412 sarcomas with complex genetics were examined by immunohistochemistry using four smooth muscle markers (calponin, h-caldesmon, transgelin and smooth muscle actin). Two tumor categories were first defined: tumors with positivity for all four markers and tumors with no or incomplete phenotypes. Multivariate analysis demonstrated that this classification method exhibited the strongest prognostic value compared with other prognostic factors, including histological classification. Secondly, incomplete or absent smooth muscle phenotype tumor group was then divided into subgroups by summing for each tumor the labeling intensities of all four markers for each tumors. A subgroup of tumors with an incomplete but strong smooth muscle differentiation phenotype presenting an intermediate metastatic risk was thus identified. Collectively, our results show that the smooth muscle differentiation classification method may be a useful diagnostic tool as well as a relevant prognostic tool for undifferentiated pleomorphic sarcomas.

Humanization of the mouse mammary gland by replacement of the luminal layer with genetically-engineered preneoplastic human cells

The cell of origin for estrogen receptor α (ERα) positive breast cancer is probably a luminal stem cell in the terminal duct lobular units. To model these cells we have used the murine myoepithelial layer in the mouse mammary ducts as a scaffold upon which to build a human luminal layer. To prevent squamous metaplasia, a common artifact in genetically engineered breast cancer models, we sought to limit activation of the epidermal growth factor receptor (EGFR) during in vitro cell culture before grafting the cells. Human reduction mammoplasty cells were grown in vitro in WIT medium. Epidermal growth factor (EGF) in the medium was replaced with amphiregulin and neuregulin to decrease activation of EGFR and increase activation of EGFR homologs 3 and 4 (ERBB3 and ERBB4). Lentiviral vectors were used to express oncogenic transgenes and fluorescent proteins. Human mammary epithelial cells were mixed with irradiated mouse fibroblasts and matrigel, then injected through the nipple into the mammary ducts of immunodeficient mice. Engrafted cells were visualized by stereomicroscopy for fluorescent proteins and characterized by histology and immunohistochemistry. Growth of normal mammary epithelial cells in conditions favoring ERBB3/4 signaling prevented squamous metaplasia in vitro. Normal human cells were quickly lost after intraductal injection but cells infected with lentiviruses expressing CCND1, MYC, TERT, BMI1 and a short hairpin RNA targeting TP53 were able to engraft and progressively replace the luminal layer in the mouse mammary ducts, resulting in the formation of an extensive network of humanized ducts. Despite expressing multiple oncogenes, the human cells formed a morphologically normal luminal layer. Expression of a single additional oncogene, PIK3CA-H1047R, converted the cells into invasive cancer cells. The resulting tumors were ERα+, Ki67+ luminal B adenocarcinomas that were resistant to treatment with fulvestrant. Injection of preneoplastic human mammary epithelial cells into the mammary ducts of immunodeficient mice leads to replacement of the murine luminal layer with morphologically normal human cells. Genetic manipulation of the injected cells makes it possible to study defined steps in the transformation of human mammary epithelial cells in a more physiological environment than has hitherto been possible.

Expression of Gastrin-Releasing Peptide Receptor (GRPR) in Breast Cancer and its Association with Pathological, Biological and Clinical Parameters: A Study of 1432 Primary Tumors

A growing body of evidence suggests that gastrin-releasing peptide receptor (GRPR) might be a valuable target in breast cancer. To understand which patients can be potential candidates for GRPR-based imaging or targeted therapy, we screened invasive breast cancers by immunohistochemistry for the presence and intensity of GRPR expression. Methods: We explored a tissue microarray of 1,432 primary breast tumors from patients who underwent surgery between 2000 and 2005 at Institut Bergonié, without prior neoadjuvant treatment. We studied associations between GRPR expression and clinical, pathologic, and biologic parameters. The association between GRPR expression and distant metastasis-free interval was also examined. Results: GRPR overexpression was found in 75.8% of the 1,432 tumors and was most strongly associated with estrogen receptor (ER) positivity (GRPR was high in 83.2% of ER-positive and 12% of ER-negative tumors; P < 0.00001). When molecular subtypes of breast cancer were considered, GRPR was overexpressed in 86.2% of luminal A–like tumors, 70.5% of luminal B–like human epidermal growth factor receptor 2 (HER2)–negative tumors, 82.8% of luminal B–like HER2-positive tumors, 21.3% of HER2-enriched tumors, and 7.8% of triple-negative tumors. Importantly, when breast tumors overexpressed GRPR, high GRPR expression was also found in metastatic lymph nodes in 94.6% of cases. Primary tumors with high GRPR expression were associated with lower risk of distant metastases at follow-up in univariate analysis (Log-rank P = 0.0084) but not in multivariate analysis. Hence, the prognostic impact of GRPR was lost when examined within specific molecular subtypes. Conclusion: Because GRPR is overexpressed in a high percentage of ER-positive tumors, GRPR targeting offers wide perspectives for imaging and treatment in patients with ER-positive breast cancer, using recently developed radiolabeled GRPR ligands.