Pituitary adenomas may develop sporadically or as part of the multiple endocrine neoplasia type 1 (MEN 1) syndrome. The gene responsible for MEN 1 syndrome was recently identified and cloned. Low rates of MEN 1 gene mutations and deletions have been reported in sporadic pituitary adenomas. To elucidate the role of the MEN 1 gene in the pathogenesis of MEN 1-associated pituitary tumors, we examined pituitary adenomas from 11 MEN 1 patients for the presence of 11q13 allelic loss. Ten of the 11 pituitary tumors were informative by PCR-based loss of heterozygosity analysis. Using a combination of family pedigree analysis and restriction analysis directed at the mutated allele in 8 of the 10 informative cases, it was demonstrated in all 8 cases that it is the wild-type allele that undergoes deletion. All 11 tumors, 4 of which were growth hormone secreting, were additionally analyzed for mutation in the Gs alpha subunit (gsp) gene. None of the tumors (0 of 11 tumors) revealed a gsp gene mutation. Therefore, genetic alterations of the MEN 1 gene seem to play a dominant role in MEN 1-associated pituitary tumorigenesis, whereas gsp gene mutations do not seem to be a frequent event in either growth hormone-secreting or other types of MEN 1-associated pituitary tumors. These results suggest that MEN 1-associated pituitary tumors develop via genetic pathways that differ from those of most sporadic pituitary tumors.
CTCF is a candidate tumor suppressor gene encoding a multifunctional transcription factor. Surprisingly for a tumor suppressor, the levels of CTCF in breast cancer cell lines and tumors were found elevated compared with breast cell lines with finite life span and normal breast tissues. In this study, we aimed to investigate the possible cause for this increase in CTCF content and in particular to test the hypothesis that up-regulation of CTCF may be linked to resistance of breast cancer cells to apoptosis. For this purpose, apoptotic cell death was monitored following alterations of CTCF levels induced by transient transfection and conditional knockdown of CTCF in various cell lines. We observed apoptotic cell death in all breast cancer cell lines examined following CTCF down-regulation. In addition, overexpression of CTCF partially protected cells from apoptosis induced by overexpression of Bax or treatment with sodium butyrate. To elucidate possible mechanisms of this phenomenon, we used a proteomics approach and observed that levels of the proapoptotic protein, Bax, were increased following CTCF down-regulation in MCF7 cells. Taken together, these results suggest that in some cellular contexts CTCF shows antiapoptotic characteristics, most likely exerting its functions through regulation of apoptotic genes. We hypothesize that CTCF overexpression may have evolved as a compensatory mechanism to protect breast cancer cells from apoptosis, thus providing selective survival advantages to these cells. The observations reported in this study may lead to development of therapies based on selective reduction of CTCF in breast cancer cells.
<p>Efficacy and determinants of response to osimertinib and savolitinib combination among osimertinib-resistant EGFR-mutant NSCLC PDX models with spatially and temporally heterogenous MET pathway activation. Tumor growth inhibition studies in <i>MET</i> polysomy (<b>A</b>) and <i>MET</i> amplified (<b>B</b>) PDXs. Dashed vertical lines delineate when treatment was stopped. Asterisks signify statistical significance between osimertinib and savolitinib combination and osimertinib alone treatment arms. <i>P</i> values were calculated by <i>t</i> test. <i>P</i> values < 0.05 were considered significant. <b>C,</b> Association between response to osimertinib and savolitinib combination and IHC features (phospho-MET, c-MET), copy number and FISH parameters (number of <i>MET</i> copies and <i>MET/CEP7</i> ratio). Response is defined as >25 days until reaching tumor size endpoint in osimertinib and savolitinib combination compared with osimertinib treatment alone. Individual circles represent a unique tumor for each represented PDX model. <b>D,</b> Representative c-MET and phospho-MET IHC images of PDX tumors with and without response to osimertinib and savolitinib combination. Scale bars, 50 µm.</p>
<div>Abstract<p>MET pathway activation is one of the most common mechanisms of resistance to osimertinib in <i>EGFR</i>-mutant non–small cell lung cancer (NSCLC). We previously demonstrated spatial and temporal heterogeneity in MET pathway activation upon osimertinib resistance in <i>EGFR</i>-mutant NSCLC; however, the functional relevance of these findings is unclear. Here, we generated 19 patient-derived xenografts (PDX) from 9 patients with multi-region and temporal sampling of osimertinib-resistant tumor tissue from patients with <i>EGFR</i>-mutant NSCLC. MET pathway activation was a putative mechanism of osimertinib resistance in 66% (<i>n</i> = 6/9) patients from whom PDXs were generated. Significant spatial and temporal heterogeneity in MET pathway activation was evident. Osimertinib-resistant PDXs with <i>MET</i> amplification by FISH (defined as <i>MET/CEP7</i> ratio ≥2.0 or mean <i>MET</i> ≥ 6.0 copies/cell) and high-level phospho-MET, but not c-MET expression, had better responses to osimertinib and savolitinib combination than to osimertinib alone. <i>MET</i> polysomy tumors by FISH from both PDXs and patients had evidence of subclonal phospho-MET expression. Select <i>MET</i> polysomy PDX tumors with phospho-MET expression responded better to osimertinib and savolitinib combination than <i>MET</i> polysomy PDX tumors without phospho-MET expression. Our results suggest osimertinib and savolitinib combination is most effective for osimertinib-resistant <i>EGFR</i>-mutant tumors with MET pathway activation as evidenced by phospho-MET. As subclonal <i>MET</i> amplification may be evident in <i>MET</i> polysomy tumor progression, <i>MET</i> polysomy warrants close clinical follow-up with phospho-MET IHC in parallel with FISH diagnostic.</p>Significance:<p>Using a novel cohort of <i>in vivo</i> PDX models of MET pathway activation with acquired resistance to osimertinib in EGFR-mutant lung cancer, we demonstrate that phospho-MET may be a clinically relevant assay to guide treatment selection with osimertinib and savolitinib combination. In addition, our work shows that patients with <i>MET</i> polysomy tumors may have subclonal <i>MET</i> amplification and therefore require close follow up for the use of osimertinib and savolitinib combination.</p></div>
<p>Heterogeneity in MET polysomy and MET amplification in osimertinib-resistant EGFR-mutant NSCLC. <b>A,</b> Representative phospho-MET IHC (several are reused from <a href="#fig2" target="_blank">Fig. 2D</a>), MET FISH images and MET FISH scoring from PDXs with <i>MET</i> polysomy. <b>B,</b> Representative phospho-MET IHC, MET FISH images and MET FISH scoring from longitudinally collected tumor samples from patient LAT006 at first progression on osimertinib, second progression after osimertinib rechallenge, and upon further progression on chemoimmunotherapy. Scale bars, 50 µm.</p>
<p>Phospho-MET expression is an indicator of MET activity post-osimertinib treatment; and proposed clinical flow diagram for treating <i>EGFR</i>-mutant NSCLC with evidence of <i>MET</i> pathway activation after osimertinib resistance. Representative phospho-MET IHC, <i>MET</i> FISH images and <i>MET</i> FISH scoring from pre- and post-osimertinib resistant tumors from patient LAT028 (multiple spatially heterogenous post-osimertinib resistant tumors shown; <b>A</b>) and from patient LAT021 (<b>B</b>). Scale bars, 50 µm. <b>C,</b> Clinical flow diagram for osimertinib-resistant <i>EGFR</i>-mutant NSCLC with evidence of MET pathway activation.</p>
Abstract We report a novel group of clinically aggressive spinal cord ependymomas characterized by Grade III histology, MYCN amplification, an absence of NF2 alterations or other recurrent pathogenic mutations, and a unique methylation classifier profile. Seven cases were found to have MYCN amplification in the course of routine mutational profiling of 552 patients with central nervous system tumors between December 2016 and July of 2019 and an eighth patient was identified from an unrelated set of cases. Methylation array analysis revealed that none of the 8 cases clustered with any of the nine previously described ependymoma methylation subgroups, and 7 of 8 formed their own tight unique cluster. Histologically all cases showed grade III features, and all demonstrated aggressive clinical behavior. These findings are presented in the context of data from three other studies describing similar cases. Therefore, a combined total of 27 MYCN amplified spinal cord ependymoma cases have now been reported in the literature, warranting their consideration as a distinctive subtype of spinal cord ependymoma (SP-EPN-MYCN) with their unique molecular characteristics and aggressive clinical behavior.
// Anish Thomas 1 , Yuanbin Chen 1 , Seth M. Steinberg 2 , Ji Luo 3 , Svetlana Pack 4 , Mark Raffeld 4 , Zied Abdullaev 4 , Christine Alewine 5 , Arun Rajan 1 , Giuseppe Giaccone 6 , Ira Pastan 5 , Markku Miettinen 4 , Raffit Hassan 1 1 Thoracic and GI Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA 2 Biostatistics and Data Management Section, Center for Cancer Research, National Institutes of Health, Bethesda, MD, USA 3 Laboratory of Cancer Biology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA 4 Laboratory of Pathology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA 5 Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA 6 Lombardi Cancer Center, Georgetown University, Washington DC, USA Correspondence to: Raffit Hassan, e-mail: hassanr@mail.nih.gov Keywords: mesothelin, non-small cell lung cancer, KRAS, EGFR Received: January 12, 2015 Accepted: February 24, 2015 Published: April 13, 2015 ABSTRACT Mesothelin is a cell surface glycoprotein which is highly expressed in several epithelial cancers and may have a role in cell adhesion and metastases. In this study, we used prospectively obtained clinical and pathological data to characterize mesothelin expression in advanced lung adenocarcinoma. Tissue was obtained from patients who underwent molecular profiling of potentially actionable genes on a trial of molecular profiling and targeted therapies in advanced thoracic malignancies. We immunohistochemically evaluated the intensity, and the percentage of cells expressing mesothelin in 93 advanced lung adenocarcinomas. The evaluation was blinded for molecular data and outcome. Mutations of EGFR, KRAS, BRAF, AKT1, PIK3CA and HER2 were assessed by pyrosequencing; HER2 amplification and ALK translocation were assessed by fluorescence in situ hybridization. 53% of advanced lung adenocarcinomas expressed mesothelin to some degree; high mesothelin expression, defined as mesothelin positivity in more than 25% of cells, was found in 24% of patients. High mesothelin expression was associated with inferior survival (median 18.2 months vs. 32.9 months; P = 0.014). High mesothelin expression was strongly associated with mutant KRAS ( P < 0.0001) and wild-type EGFR ( P = 0.002). Our results provide strong rationale to explore anti-mesothelin targeted therapies in advanced lung adenocarcinoma especially in the KRAS -mutant subgroup.
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