An investigation into the role of C-terminal tensin-like protein (Cten) in melanomagenesis

C-terminal tensin-like protein (Cten) is a focal adhesion protein with no or limited protein expression in normal tissues, which has recently been reported to be overexpressed and act as an oncoprotein in numerous cancers. Since its expression status in human cutaneous melanoma is currently unknown, I used tissue microarrays and immunohistochemical staining to examine the protein expression of Cten throughout melanoma progression. I found that Cten was significantly up-regulated in dysplastic nevi (DN) compared to normal nevi (NN), and in primary melanoma (PM) compared to both DN and NN. Strong Cten staining was associated with a poorer 5- and 10-year overall and disease-specific survival for PM patients, and was an adverse independent prognostic factor for the 5-year survival of the same patients. In vitro studies using two melanoma cell lines supported these findings and indicated that Cten functions as an oncogene in melanoma. Since relatively little is known about how Cten contributes to tumorigenesis, I next investigated the expression profile of the RhoGAP Deleted in Liver Cancer-1 (DLC1), the only protein known to bind to Cten, in melanomas. Both cytoplasmic and nuclear DLC1 were detected, and both were down-regulated in metastatic melanoma (MM) compared to PM and nevi, with nuclear DLC1 expression additionally being reduced in PM compared to nevi. Both cytoplasmic and nuclear DLC1 were associated with the 5-year overall and disease-specific survival of all melanoma and MM patients, and with the disease-specific 10-year survival of all melanoma patients. Combined analysis of cytoplasmic and nuclear DLC1 revealed that for MM patients, concurrent loss of both cytoplasmic and nuclear DLC1 was associated with the worst survival outcome, with loss of either or both forms being a significant adverse independent prognostic factor for the 5-year survival of all melanoma and MM patients. A preliminary investigation into the relationship between Cten and DLC1 indicated that the effects of Cten on patient survival were dependent on the levels of DLC1, as expected. In summary, I here provide an initial characterization of the expression status and role of Cten in melanomagenesis, and speculate that it functions partly via interactions with the tumour suppressor DLC1.Medicine, Faculty ofMedicine, Department ofExperimental Medicine, Division ofGraduat

Expression of the RNase III enzyme DROSHA is reduced during progression of human cutaneous melanoma

Aberrant expression of miRNAs and their biogenesis factors has been frequently observed in different types of cancer. We recently reported that expression of DICER1 is reduced in metastatic melanoma. Nevertheless, so far very little is known about the expression pattern of other miRNA biogenesis factors in this type of malignancy. Here, we investigated the expression pattern of DROSHA in a large set of melanocytic lesions by tissue microarray and immunohistochemistry (n = 409). We found that nuclear expression of DROSHA is markedly reduced in the early stages of melanoma progression (P = 0.0001) and is inversely correlated with melanoma thickness (P = 0.0001), AJCC stages (P = 0.0001), and ulceration status (P = 0.002). We also confirmed the reduced expression of nuclear DROSHA by a second specific antibody raised against a different region of the DROSHA protein. In addition, we observed that the reduced nuclear expression of DROSHA during melanoma progression is accompanied by an increased cytoplasmic expression of this protein (P = 0.0001). Finally, we found that expression pattern of DROSHA varies from that of DICER1 and concomitant loss of expression of both DICER1 and DROSHA confers the worse outcome for melanoma patients. Our results demonstrate a reduced nuclear expression of DROSHA which further highlights a perturbed miRNA biogenesis pathway in melanoma. In addition, the aberrant subcellular localization of DROSHA indicates possible deregulation in the mechanisms responsible for its proper localization in the nucleus

C-terminal tensin-like protein is a novel prognostic marker for primary melanoma patients.

C-terminal tensin-like protein (Cten) is a focal adhesion protein originally identified as a tumor suppressor in prostate cancer. It has since been found to be overexpressed and function as an oncogene in numerous other cancers, but the expression status of Cten in melanoma is still unknown.Using tissue microarrays containing 562 melanocytic lesions, we evaluated Cten protein expression by immunohistochemistry. The association between Cten expression and patient survival was examined using Kaplan-Meier survival analysis, and univariate and multivariate Cox regression analyses were used to estimate the crude and adjusted hazard ratios.Strong Cten expression was detected in 7%, 24%, 41%, and 46% of normal nevi, dysplastic nevi, primary melanoma, and metastatic melanoma samples, respectively, and Cten expression was found to be significantly higher in dysplastic nevi compared to normal nevi (P = 0.046), and in primary melanoma compared to dysplastic nevi (P = 0.003), but no difference was observed between metastatic and primary melanoma. Cten staining also correlated with AJCC stages (P = 0.015) and primary tumor thickness (P = 0.002), with Cten expression being induced in the transition from thin (<1 mm) to thick (≥1 mm) melanomas. Strong Cten expression was significantly associated with a worse 5-year overall (P = 0.008) and disease-specific survival (P = 0.004) for primary melanoma patients, and multivariate Cox regression analysis revealed that Cten expression was an independent prognostic marker for these patients (P = 0.038 for overall survival; P = 0.021 for disease-specific survival).Our findings indicate that induction of Cten protein expression is a relatively early event in melanoma progression, and that Cten has the potential to serve as a prognostic marker for primary melanoma patients

C-Terminal Tensin-Like Protein Is a Novel Prognostic Marker for Primary Melanoma Patients

Background: C-terminal tensin-like protein (Cten) is a focal adhesion protein originally identified as a tumor suppressor in prostate cancer. It has since been found to be overexpressed and function as an oncogene in numerous other cancers, but the expression status of Cten in melanoma is still unknown. Methods: Using tissue microarrays containing 562 melanocytic lesions, we evaluated Cten protein expression by immunohistochemistry. The association between Cten expression and patient survival was examined using Kaplan-Meier survival analysis, and univariate and multivariate Cox regression analyses were used to estimate the crude and adjusted hazard ratios. Results: Strong Cten expression was detected in 7%, 24%, 41%, and 46 % of normal nevi, dysplastic nevi, primary melanoma, and metastatic melanoma samples, respectively, and Cten expression was found to be significantly higher in dysplastic nevi compared to normal nevi (P = 0.046), and in primary melanoma compared to dysplastic nevi (P = 0.003), but no difference was observed between metastatic and primary melanoma. Cten staining also correlated with AJCC stages (P = 0.015) and primary tumor thickness (P = 0.002), with Cten expression being induced in the transition from thin (&lt;1mm) to thick (≥1mm) melanomas. Strong Cten expression was significantly associated with a worse 5-year overall (P = 0.008) and disease-specific survival (P = 0.004) for primary melanom

Kaplan-Meier analyses for the correlations between primary tumor thickness, Cten expression, and patient survival.

<p>(A) Tumors ≥1mm thick (n=192) were significantly associated with a poorer overall and disease-specific survival for primary melanoma patients compared to tumors <1mm thick (n=79, P < 0.001 for both, log-rank tests). (B) Strong Cten staining was significantly associated with a poorer overall and disease-specific 5-year survival for patients with tumors ≥1mm thick (black lines, P = 0.031 and 0.022, respectively) but not with tumors <1mm thick (gray lines, P = 0.939 and 0.857, respectively). A significant difference was also observed between tumors <1mm thick with neg-mod Cten expression and tumors ≥1mm thick with neg-mod (P = 0.014 and 0.009, respectively) or strong Cten expression (P = 0.001 and <0.001, respectively), and between tumors <1mm thick with strong Cten expression and tumors ≥1mm thick with strong Cten expression (P = 0.007 for both), but not between tumors <1mm thick with strong Cten expression and tumors ≥1mm with neg-mod Cten expression (P = 0.085 and 0.098, respectively, P < 0.001 overall, log-rank tests).</p

Representative images of Cten protein expression at 100x (A-D) and 400x magnification (E-H).

<p>(A, E) Weak Cten staining in normal nevi (NN). (B, F) Moderate Cten staining in dysplastic nevi (DN). (C, G) Strong Cten staining in primary melanoma (PM). (D, H) Strong Cten staining in metastatic melanoma (MM). (I) Correlation between Cten expression and melanoma progression.</p

Kaplan-Meier analysis for the correlation between Cten expression and 5-year survival in 271 primary melanoma patients.

<p>Strong Cten expression was significantly associated with a worse overall and disease-specific 5-year survival for primary melanoma patients (P = 0.008 and 0.004, respectively, log-rank tests).</p

Decreased Expression of Nuclear p300 Is Associated with Disease Progression and Worse Prognosis of Melanoma Patients

<div><p>Background</p><p>Genomic instability due to UV radiation is one of the leading causes for melanoma. Histone acetyltransferase p300 plays an indispensible role in DNA repair and maintenance of genomic integrity. The present study was performed to analyze the correlation between p300 expression, melanoma progression and patient survival.</p><p>Methods</p><p>Tissue microarray and immunohistochemical analysis was employed to study the expression of p300 in melanoma patients. A total of 358 melanoma patients (250 primary melanoma and 108 metastatic melanoma) were used for the study. Kaplan-Meier, univariate and multivariate Cox regression analysis, and receiver-operating characteristic curves, were used to elucidate the prognostic significance of p300 expression.</p><p>Results</p><p>Our results demonstrate that p300 is expressed in both nucleus and cytoplasm but the nuclear expression of p300 is predominant. The progression of disease from dysplastic nevi to primary melanoma and to metastatic melanoma was associated with decreased nuclear and increased cytoplasmic p300 expression. Especially, the loss of nuclear and gain in cytoplasmic p300 was correlated with the progression of melanoma from AJCC stage II to stage III, which requires the migration and metastasis of cancer cells from primary sites to lymph nodes. Similarly, decrease in nuclear, and increase in cytoplasmic p300 expression correlated with worse survival of melanoma patients. Nuclear p300 but not cytoplasmic p300 could predict the patient survival independent of AJCC stage, age and gender.</p><p>Conclusion</p><p>Loss of nuclear p300 expression is an indicator of worse patient survival and is an independent prognostic marker for melanoma.</p></div

p300 is expressed in both nucleus and cytoplasm Silencing of p300 leads to abrogation of p300 expression in both nucleus and cytoplasm.

<p>Cells were grown on cover slips and transfected either with control siRNA (siCtrl) or p300 siRNA (si-p300) and after 48 hrs fixed as described in the methods section. Immunofluorescent staining was performed on the cells grown on cover slips using anti-p300 antibody (green). Nucleus was stained with DAPI (blue).</p

p300 expression in melanoma patients.

<p>(A) Representative images at 100× (upper panel) and 400× (lower panel) magnification of normal nevi (NN) and dysplastic nevi (DN) with strong and primary melanoma (PM) and metastatic melanoma (MM) with weak nuclear p300 staining. (B) Nuclear p300 staining is significantly decreased from normal and dysplastic nevi to melanoma by Kruskal-Wallis test. (C) Percentage of strong p300 staining in nuclei is significantly decreased from normal and dysplastic nevi to melanoma by χ² test. (D) Cytoplasmic p300 staining is significantly increased from nevi to melanoma as studied by Kruskal-Wallis test. (E) Percentage of strong cytoplasmic staining is significantly increased from nevi to melanoma by χ² test. **<i>P</i><.01, ***<i>P</i><.001.</p