The Sertoli cell tumor (SCT) of the testis is a sex cord stromal tumor, usually sporadic, rarely associated with genetic syndromes. Much remains unclear about the molecular genetic changes involved in SCT and its histogenesis. Recently, nuclear β-catenin immunostaining has been reported in a case of bilateral SCT, but the molecular basis of the aberrant nuclear β-catenin expression remains uncertain. In the present study, β-catenin immunohistochemical assay and mutational analysis of exon 3 of the CTNNB1 gene by direct sequencing were performed in 14 SCTs, 2 of which had an unfavorable clinical course. Immunohistochemical study showed that β-catenin was located in the cytoplasm of tumor cells in 4 cases (28.6%) and in both the nuclei and the cytoplasm in the remaining 10 cases (71.4%). β-Catenin mutations were detected in 10 of the 14 patients (71.4%) under evaluation. Ten of 10 mutation-carrying cases showed strong nuclear and diffuse cytoplasmic β-catenin immunoreactivity. Seven of the 8 CTNNB1-mutated tumors tested for cyclin D1 displayed diffuse immunoreactivity in the nuclei of tumor cells. We conclude that CTNNB1 exon 3 mutations are likely to be involved in the pathogenesis of male SCT with nuclear accumulation of β-catenin and affect the expression of cyclin D1.

Running title: Gut microbiota implication in response to trastuzumab therapy.

No abstract

The Leydig cell tumour Scaled Score (LeSS): a method to distinguish benign from malignant cases, with additional correlation with MDM2 and CDK4 amplification Aims: To investigate the morphological and molecular characteristics of Leydig cell tumours (LCTs) of the testis for the identification of cases that may metastasise. Methods and results: Six parameters for a predictive model of the metastatic risk were evaluated in 37 benign and 14 malignant LCTs of the testis [LCT Scaled Score (LeSS)]. The tumour size (benign LCTs, mean 13.3 mm; malignant LCTs, mean 44 mm) (P < 0.001) and five other parameters (infiltrative margins, necrosis, vascular invasion, mitotic count, and nuclear atypia) showed significant differences (Wilcoxon's test, P < 0.001). Eight metastatic LCTs and one benign LCT had infiltrative margins. Foci of coagulative necrosis occurred in 10 metastatic LCTs, whereas vascular invasion was identified in nine of 14 metastatic LCTs and none of 37 benign LCTs. Benign LCTs showed <2 mitoses/10 high-power fields (HPFs), whereas a high mitotic count (range, 3-50 mitoses/10 HPFs) was a feature of malignant LCTs. These parameters were selected by use of an inferential analysis based on univariate logistic regression models to develop a score. A LeSS of <4 correctly identified all histologically and clinically benign LCTs. A LeSS of ≥4 correctly identified all malignant LCTs. MDM2 and CDK4 immunostains were applied in all 51 cases: benign LCTs were negative; three of 11 malignant LCTs (27%) showed strong and diffuse immunopositivity and high levels of MDM2 and CDK4 amplification as determined with fluorescence in-situ hybridisation analysis and next-generation sequencing. Conclusion: We provide a new tool, the LeSS, for the prediction of malignant behaviour in LCTs.

This study solved some of the methodological doubts concerning the study of bystander effects by means of the medium transfer technique; moreover it also highlighted some experimental aspects that need to be considered when approaching this sort of experiments.