Location, location, location: the BRMS1 protein and melanoma progression

The metastasis suppressor, BRMS1, has been demonstrated to cause dramatic regression of metastatic lesions without blocking orthotopic tumor growth. The role of BRMS1 is well-documented for several non-melanoma malignancies, such as breast cancer, ovarian cancer and non-small-cell lung cancer. However, its role in melanoma is just beginning to be understood, with a recent article by Slipicevic et al. highlighting the levels of expression of BRMS1 in benign nevi, primary and metastatic melanoma samples. Their findings emphasize that the intracellular location of BRMS1 protein (cytoplasmic or nuclear), appears to have a significant impact upon the metastatic capacity of melanoma cells. Interestingly, this selective localization translates into a statistically significant decrease in the relapse-free period in melanoma patients, further associated with a thicker Breslow's depth of primary melanomas. However, and more importantly, this study begins to define a clearer role for BRMS1 in melanoma that is strictly dependent upon its cellular location, with nuclear expression associated with invasive and metastatic capacity and cytoplasmic expression resulting in repressive effects upon progression and metastasis

Mitf-Mdel, a novel melanocyte/melanoma-specific isoform of microphthalmia-associated transcription factor-M, as a candidate biomarker for melanoma

<p>Abstract</p> <p>Background</p> <p>Melanoma incidence is on the rise and advanced melanoma carries an extremely poor prognosis. Treatment options, including chemotherapy and immunotherapy, are limited and offer low response rates and transient efficacy. Thus, identification of new melanocyte/melanoma antigens that serve as potential novel candidate biomarkers in melanoma is an important area for investigation.</p> <p>Methods</p> <p>Full length MITF-M and its splice variant cDNA were cloned from human melanoma cell line 624 mel by reverse transcription polymerase chain reaction (RT-PCR). Expression was investigated using regular and quantitative RT-PCR in three normal melanocytes (NHEM), 31 melanoma cell lines, 21 frozen melanoma tissue samples, 18 blood samples (pheripheral blood mononuclear cell; PBMC) from healthy donors and 12 non-melanoma cancer cell lines, including three breast, five glioma, one sarcoma, two kidney and one ovarian cancer cell lines.</p> <p>Results</p> <p>A novel splice variant of MITF-M, which we named MITF-Mdel, was identified. The predicted MITF-Mdel protein contains two in frame deletions, 56- and 6- amino acid deletions in exon 2 (from V32 to E87) and exon 6 (from A187 to T192), respectively. MITF-Mdel was widely expressed in melanocytes, melanoma cell lines and tissues, but almost undetectable in non-melanoma cell lines or PBMC from healthy donors. Both isoforms were expressed significantly higher in melanoma tissues than in cell lines. Two of 31 melanoma cell lines expressed only one isoform or the other.</p> <p>Conclusion</p> <p>MITF-Mdel, a novel melanocyte/melanoma-specific isoform of MITF-M, may serve as a potential candidate biomarker for diagnostic and follow-up purposes in melanoma.</p

Successful removal of a giant intrathoracic lipoma: a case report and review of the literature

We report a case of a 44-year old female who presented to her physician complaining of mild dyspnea. A follow-up chest X-ray and chest computed tomography scan revealed a giant bilateral intrathoracic mass, filling the right thoracic cavity and extending across the anterior mediastinum into the left chest cavity. This large mass caused a marked shift in the midline structures, displacing the heart to the left hemi-thorax. The patient underwent surgical removal of the thoracic and breast mass, with histologic examination confirming the diagnosis of a giant intrathoracic lipoma, weighing 4,320 grams and measured 34 × 28 × 11 cm. It is the largest intrathoracic lipoma documented in the modern literature

Carcinosarcoma of the breast: two case reports and review of the literature

Carcinosarcoma of the breast, often referred to as metaplastic carcinoma of the breast, is a rare malignancy with two distinct cell lines described as a breast carcinoma of ductal type with a sarcoma-like component. Clinically, carcinosarcoma of the breast is an aggressive breast cancer. The prognosis for carcinosarcoma of the breast is less favorable compared to more common types of breast cancer such as infiltrating ductal or lobular carcinoma. Currently, the evaluation of breast carcinoma includes hormone receptor analysis of the tumor tissue, with those positive for estrogen or progesterone responding better to both hormonal and chemotherapy

Identification of a Mutated Fibronectin As a Tumor Antigen Recognized by CD4+T Cells: Its Role in Extracellular Matrix Formation and Tumor Metastasis

CD4+ T cells play an important role in orchestrating host immune responses against cancer, particularly by providing critical help for priming and extending the survival of CD8+ T cells. However, relatively little is known about major histocompatibility complex class II–restricted human tumor antigens capable of activating CD4+ T cells. Here, we describe the identification of a mutated fibronectin (FN) as a tumor antigen recognized by human histocompatibility leukocyte antigen-DR2–restricted CD4+ T cells. Deoxyribonucleic acid (DNA) sequencing analysis indicated that this gene contains a mutation that results in the substitution of lysine for glutamic acid and gives rise to a new T cell epitope recognized by CD4+ T cells. Tumor cells harboring the mutant FN resulted in the loss of FN matrix formation and the gain of metastatic potential based on the migration pattern compared with that of tumor cells that express wild-type FN. Additional experiments using cell lines stably expressing the mutated FN cDNA demonstrated that the point mutation in FN was responsible for the loss of FN staining in extracellular matrices and the enhancement of tumor cell migration. These findings represent the first demonstration that a mutated gene product recognized by CD4+ T cells is directly involved in tumor metastasis, which indicates the importance of CD4+ T cells in controlling the spread of tumor cells to distant anatomic sites

The gene expression profiles of primary and metastatic melanoma yields a transition point of tumor progression and metastasis

<p>Abstract</p> <p>Background</p> <p>The process of malignant transformation, progression and metastasis of melanoma is poorly understood. Gene expression profiling of human cancer has allowed for a unique insight into the genes that are involved in these processes. Thus, we have attempted to utilize this approach through the analysis of a series of primary, non-metastatic cutaneous tumors and metastatic melanoma samples.</p> <p>Methods</p> <p>We have utilized gene microarray analysis and a variety of molecular techniques to compare 40 metastatic melanoma (MM) samples, composed of 22 bulky, macroscopic (replaced) lymph node metastases, 16 subcutaneous and 2 distant metastases (adrenal and brain), to 42 primary cutaneous cancers, comprised of 16 melanoma, 11 squamous cell, 15 basal cell skin cancers. A Human Genome U133 Plus 2.0 array from Affymetrix, Inc. was utilized for each sample. A variety of statistical software, including the Affymetrix MAS 5.0 analysis software, was utilized to compare primary cancers to metastatic melanomas. Separate analyses were performed to directly compare only primary melanoma to metastatic melanoma samples. The expression levels of putative oncogenes and tumor suppressor genes were analyzed by semi- and real-time quantitative RT-PCR (qPCR) and Western blot analysis was performed on select genes.</p> <p>Results</p> <p>We find that primary basal cell carcinomas, squamous cell carcinomas and thin melanomas express dramatically higher levels of many genes, including <it>SPRR1A/B</it>, <it>KRT16/17</it>, <it>CD24</it>, <it>LOR</it>, <it>GATA3</it>, <it>MUC15</it>, and <it>TMPRSS4</it>, than metastatic melanoma. In contrast, the metastatic melanomas express higher levels of genes such as <it>MAGE</it>, <it>GPR19</it>, <it>BCL2A1</it>, <it>MMP14</it>, <it>SOX5</it>, <it>BUB1</it>, <it>RGS20</it>, and more. The transition from non-metastatic expression levels to metastatic expression levels occurs as melanoma tumors thicken. We further evaluated primary melanomas of varying Breslow's tumor thickness to determine that the transition in expression occurs at different thicknesses for different genes suggesting that the "transition zone" represents a critical time for the emergence of the metastatic phenotype. Several putative tumor oncogenes (<it>SPP-1</it>, <it>MITF</it>, <it>CITED-1</it>, <it>GDF-15</it>, <it>c-Met</it>, <it>HOX </it>loci) and suppressor genes (<it>PITX-1</it>, <it>CST-6</it>, <it>PDGFRL</it>, <it>DSC-3</it>, <it>POU2F3</it>, <it>CLCA2</it>, <it>ST7L</it>), were identified and validated by quantitative PCR as changing expression during this transition period. These are strong candidates for genes involved in the progression or suppression of the metastatic phenotype.</p> <p>Conclusion</p> <p>The gene expression profiling of primary, non-metastatic cutaneous tumors and metastatic melanoma has resulted in the identification of several genes that may be centrally involved in the progression and metastatic potential of melanoma. This has very important implications as we continue to develop an improved understanding of the metastatic process, allowing us to identify specific genes for prognostic markers and possibly for targeted therapeutic approaches.</p

Cystatin E/M suppresses legumain activity and invasion of human melanoma

<p>Abstract</p> <p>Background</p> <p>High activity of cysteine proteases such as legumain and the cathepsins have been shown to facilitate growth and invasion of a variety of tumor types. In breast cancer, several recent studies have indicated that loss of the cysteine protease inhibitor cystatin E/M leads to increased growth and metastasis. Although cystatin E/M is normally expressed in the skin, its role in cysteine protease regulation and progression of malignant melanoma has not been studied.</p> <p>Methods</p> <p>A panel of various non-melanoma and melanoma cell lines was used. Cystatin E/M and C were analyzed in cell media by immunoblotting and ELISA. Legumain, cathepsin B and L were analyzed in cell lysates by immunoblotting and their enzymatic activities were analyzed by peptide substrates. Two melanoma cell lines lacking detectable secretion of cystatin E/M were transfected with a cystatin E/M expression plasmid (pCST6), and migration and invasiveness were studied by a Matrigel invasion assay.</p> <p>Results</p> <p>Cystatin E/M was undetectable in media from all established melanoma cell lines examined, whereas strong immunobands were detected in two of five primary melanoma lines and in two of six lines derived from patients with metastatic disease. Among the four melanoma lines secreting cystatin E/M, the glycosylated form (17 kD) was predominant compared to the non-glycosylated form (14 kD). Legumain, cathepsin B and L were expressed and active in most of the cell lines, although at low levels in the melanomas expressing cystatin E/M. In the melanoma lines where cystatin E/M was secreted, cystatin C was generally absent or expressed at a very low level. When melanoma cells lacking secretion of cystatin E/M were transfected with pCST6, their intracellular legumain activity was significantly inhibited. In contrast, cathepsin B activity was not affected. Furthermore, invasion was suppressed in cystatin E/M over-expressing melanoma cell lines as measured by the transwell Matrigel assay.</p> <p>Conclusions</p> <p>These results suggest that the level of cystatin E/M regulates legumain activity and hence the invasive potential of human melanoma cells.</p

Explaining Institutional Change: Why Elected Politicians Implement Direct Democracy

In existing models of direct democratic institutions, the median voter benefits, but representative politicians are harmed since their policy choices can be overridden. This is a puzzle, since representative politicians were instrumental in creating these institutions. I build a model of direct democracy that explains why a representative might benefit from tying his or her own hands in this way. The key features are (1) that voters are uncertain about their representative's preferences; (2) that direct and representative elections are complementary ways for voters to control outcomes. The model shows that some politicians benefit from the introduction of direct democracy, since they are more likely to survive representative elections: direct democracy credibly prevents politicians from realising extreme outcomes. Historical evidence from the introduction of the initiative, referendum and recall in America broadly supports the theory, which also explains two empirical results that have puzzled scholars: legislators are trusted less, but reelected more, in US states with direct democracy. I conclude by discussing the potential for incomplete information and signaling models to improve our understanding of institutional change more generally