Faculty Bibliography

Carney complex is a syndrome that may include cardiac and mucocutaneous myxomas, spotting skin pigmentation, and endocrine lesions. Many patients with Carney complex have been shown to have a stop codon mutation in the PRKAR1A gene in the 17q22-24 region. Here we present the case of a 57 year-old man with multiple skin lesions and cardiac myxomas. Histology of the skin lesions showed lentigenous melanocytic hyperplasia and cutaneous myxomas, confirming the diagnosis of Carney complex. Lesional and control normal tissue from the patient were identified and sequenced for the PRKAR1A gene. A germline missense mutation was identified at exon 1A. This is the first report of this mutation, and one of the few reported missense mutation associated with Carney complex. This finding strengthens the argument that there are alternative ways in which the protein kinase A 1-alpha subunit plays a role in tumorigenesis

ABSTRACT: BACKGROUND: The goal of our study was to investigate the molecular underpinnings associated with the relatively aggressive clinical behavior of prostate cancer (PCa) in African American (AA) compared to Caucasian American (CA) patients using a genome-wide approach. METHODS: AA and CA patients treated with radical prostatectomy (RP) were frequency matched for age at RP, Gleason grade, and tumor stage. Array-CGH (BAC SpectralChip2600) was used to identify genomic regions with significantly different DNA copy number between the groups. Gene expression profiling of the same set of tumors was also evaluated using Affymetrix HG-U133 Plus 2.0 arrays. Concordance between copy number alteration and gene expression was examined. A second aCGH analysis was performed in a larger validation cohort using an oligo-based platform (Agilent 244K). RESULTS: BAC-based array identified 27 chromosomal regions with significantly different copy number changes between the AA and CA tumors in the first cohort (Fisher's exact test, P < 0.05). Copy number alterations in these 27 regions were also significantly associated with gene expression changes. aCGH performed in a larger, independent cohort of AA and CA tumors validated 4 of the 27 (15%) most significantly altered regions from the initial analysis (3q26, 5p15-p14, 14q32, and 16p11). Functional annotation of overlapping genes within the 4 validated regions of AA/CA DNA copy number changes revealed significant enrichment of genes related to immune response. CONCLUSIONS: Our data reveal molecular alterations at the level of gene expression and DNA copy number that are specific to African American and Caucasian prostate cancer and may be related to underlying differences in immune response

BACKGROUND: Sorafenib monotherapy in patients with metastatic melanoma was explored in this multi-institutional phase II study. In correlative studies the impact of sorafenib on cyclin D1 and Ki67 was assessed. METHODOLOGY/PRINCIPAL FINDINGS: Thirty-six patients treatment-naive advanced melanoma patients received sorafenib 400 mg p.o. twice daily continuously. Tumor BRAF(V600E) mutational status was determined by routine DNA sequencing and mutation-specific PCR (MSPCR). Immunohistochemistry (IHC) staining for cyclin D1 and Ki67 was performed on available pre- and post treatment tumor samples. The main toxicities included diarrhea, alopecia, rash, mucositis, nausea, hand-foot syndrome, and intestinal perforation. One patient had a RECIST partial response (PR) lasting 175 days. Three patients experienced stable disease (SD) with a mean duration of 37 weeks. Routine BRAF(V600E) sequencing yielded 27 wild-type (wt) and 6 mutant tumors, whereas MSPCR identified 12 wt and 18 mutant tumors. No correlation was seen between BRAF(V600E) mutational status and clinical activity. No significant changes in expression of cyclin D1 or Ki67 with sorafenib treatment were demonstrable in the 15 patients with pre-and post-treatment tumor samples. CONCLUSIONS/SIGNIFICANCE: Sorafenib monotherapy has limited activity in advanced melanoma patients. BRAF(V600E) mutational status of the tumor was not associated with clinical activity and no significant effect of sorafenib on cyclin D1 or Ki67 was seen, suggesting that sorafenib is not an effective BRAF inhibitor or that additional signaling pathways are equally important in the patients who benefit from sorafenib. TRIAL REGISTRATION: Clinical Trials.gov NCT00119249

Cancer is a disease consisting of both genetic and epigenetic changes. Although increasing evidence demonstrates that tumour progression entails chromatin-mediated changes such as DNA methylation, the role of histone variants in cancer initiation and progression currently remains unclear. Histone variants replace conventional histones within the nucleosome and confer unique biological functions to chromatin. Here we report that the histone variant macroH2A (mH2A) suppresses tumour progression of malignant melanoma. Loss of mH2A isoforms, histone variants generally associated with condensed chromatin and fine-tuning of developmental gene expression programs, is positively correlated with increasing malignant phenotype of melanoma cells in culture and human tissue samples. Knockdown of mH2A isoforms in melanoma cells of low malignancy results in significantly increased proliferation and migration in vitro and growth and metastasis in vivo. Restored expression of mH2A isoforms rescues these malignant phenotypes in vitro and in vivo. We demonstrate that the tumour-promoting function of mH2A loss is mediated, at least in part, through direct transcriptional upregulation of CDK8. Suppression of CDK8, a colorectal cancer oncogene, inhibits proliferation of melanoma cells, and knockdown of CDK8 in cells depleted of mH2A suppresses the proliferative advantage induced by mH2A loss. Moreover, a significant inverse correlation between mH2A and CDK8 expression levels exists in melanoma patient samples. Taken together, our results demonstrate that mH2A is a critical component of chromatin that suppresses the development of malignant melanoma, a highly intractable cutaneous neoplasm

Background: Skp2, a known oncogene, is overexpressed in several types of tumors and is associated with worse recurrence rate and overall survival in primary melanoma patients. Moreover, the anti-proliferative effects of Skp2 siRNA on various tumor cell lines have prompted the preclinical testing of Skp2 small molecule inhibitors. In this study, we assessed the clinical relevance and molecular mechanism(s) underlying Skp2 overexpression in metastatic melanoma patients. Methods: Skp2 protein levels were measured in 122 metastatic melanoma specimens using immunohistochemistry (IHC), and the association between Skp2 overexpression and post-recurrence survival was examined. Moreover, 22 cell lines (2 normal primary melanocytes, 2 primary immortal melanocytes, 4 primary melanoma cell lines, and 18 metastatic melanoma cell lines) were evaluated for Skp2 genomic amplification using Single Nucleotide Polymorphism (SNP) arrays (Affymetrix 6.0) and Skp2 gene expression using mRNA arrays (Affymetrix U133A 2.0) and quantitative RT-PCR. We also screened 18 cell lines for Skp2 mutation by sequencing. Results: Skp2 overexpression, defined as >25% tumor cells, was associated with shorter 3-yr post-recurrence survival (37%) compared to Skp2 expression <= 25% (55%) (HR=1.89, 95%, CI= 1.04, 3.42, p=0.04). Skp2 overexpression was significantly associated with the site of melanoma metastasis: visceral (n= 12; 89%), lymph node (n=49; 36%), brain (n=15; 14%), and soft-tissue (n=36; 6%) (p<0.001). SNP array revealed genomic amplification at the Skp2 locus in 6 (33%) metastatic cell lines and one primary melanoma cell line. Skp2 genomic amplification was associated with increased transcript expression. No Skp2 mutations were identified. Conclusions: Skp2 protein overexpression is associated with worse prognosis in metastasis in melanoma. Our results also support that gene amplification, rather than a Skp2 gene mutation, may be the major mechanism responsible for Skp2 aberrant expression in metastatic melanoma

Background: Several studies have provided evidence that solid tumors are polyclonal malignancies, an observation which may contribute to difficulties in achieving durable treatment responses. In some patients, molecularly targeted therapies may be compromised due to heterogeneity among tumor subclones. In this study we compared conventional DNA sequencing with a fluorescent-based mutant-specific PCR (MS-PCR) assay to detect the BRAF hotspot mutation V600E in a large panel of patient tumors, including paired primary and metastatic tumors from individual patients. Methods: BRAF MS-PCR and conventional sequencing were performed on DNA from 304 tumors (112 melanoma, 110 ovarian, 82 prostate) to determine the presence of the BRAFV600E hot-spot mutation. Among the melanomas were 18 matched primary and metastatic specimens, and 40 metastatic specimens from 19 patients, each of whom had 2 or more metastases. Results: DNA sequencing detected mutations in 5/110 (4.5%) ovarian tumors, 1/82 (1.2%) prostate tumors, and 36/112 (32%) melanomas. In contrast, the MS-PCR assay detected mutations in 12/110 (11%) ovarian tumors, 15/82 (18%) prostate tumors and 85/112 (76%) melanomas. The presence of contaminating normal tissue was scored for each melanoma sample, but excess normal tissue did not influence the results using either methodology. In all cases mutations detected by sequencing were also detected by MSPCR. Among 18 patients with matched primary and metastatic melanoma, 8/18 (44%) had discordant results including 2 patients with mutant primary tumors and wild-type metastases; among the 19 patients with multiple metastases 5/19 (26%) had discordant (both wild-type and mutant) tumors. Conclusions: Using a highly sensitive BRAF mutation detection method, we observed substantial evidence for heterogeneity within clinical tumor specimens. This was especially true in melanoma samples, where multiple specimens from individual patients differed with respect to the presence of the mutant BRAF allele. These results suggest that failures of molecularly targeted therapies, such as those directed against mutant BRAF, may be due in part to a lack of clonality among the tumors under treatment