恶性黑色素瘤患者ＭＧＭＴ基因启动子甲基化研究

目的　分析中国恶性黑色素瘤患者ＭＧＭＴ启动子甲基化水平和蛋白表达的关系。方法　通过ＭＳ-ＰＣＲ方法检测４４例恶性黑色素瘤患者ＭＧＭＴ启动子甲基化水平,免疫组化法检测ＭＧＭＴ蛋白的表达。结果　４４例恶性黑色素瘤患者的ＭＧＭＴ启动子甲基化率为４０.９％（１８／４４）,ＭＧＭＴ启动子甲基化患者的ＭＧＭＴ蛋白表达率为２７.８％（５／１８）,非甲基化患者的ＭＧＭＴ蛋白表达率为６５.４％（１７／２６）,ＭＧＭＴ启动子甲基化与ＭＧＭＴ蛋白的低表达有相关性（Ｐ＝０.０１４）。结论　在晚期恶性黑色素瘤中ＭＧＭＴ启动子甲基化可能降低ＭＧＭＴ蛋白的表达,提示可以通过分析晚期黑色素瘤患者ＭＧＭＴ基因启动子甲基化状态,预测患者对烷化剂类药物的敏感性,为实现个体化治疗提供理论和实践依据。     

MGMT gene promoter methylation correlates with tolerance of temozolomide treatment in melanoma but not with clinical outcome

Background:

Despite limited clinical efficacy, treatment with dacarbazine or temozolomide (TMZ) remains the standard therapy for metastatic melanoma. In glioblastoma, promoter methylation of the counteracting DNA repair enzyme O⁶-methylguanine-DNA-methyltransferase (MGMT) correlates with survival of patients exposed to TMZ in combination with radiotherapy. For melanoma, data are limited and controversial.

Methods:

Biopsy samples from 122 patients with metastatic melanoma being treated with TMZ in two multicenter studies of the Dermatologic Cooperative Oncology Group were investigated for MGMT promoter methylation. We used the COBRA (combined bisulphite restriction analysis) technique to determine aberrant methylation of CpG islands in small amounts of genomic DNA isolated from paraffin-embedded tissue sections. To detect aberrant methylation, bisulphite-treated DNA was amplified by PCR, enzyme restricted, and visualised by gel electrophoresis.

Results:

Correlation with clinical data from 117 evaluable patients in a best-response evaluation indicated no statistically significant association between MGMT promoter methylation status and response. A methylated MGMT promoter was observed in 34.8% of responders and 23.4% of non-responders (P=0.29). In addition, no survival advantage for patients with a methylated MGMT promoter was detectable (P=0.79). Interestingly, we found a significant correlation between MGMT methylation and tolerance of therapy. Patients with a methylated MGMT promoter had more severe adverse events, requiring more TMZ dose reductions or discontinuations (P=0.007; OR 2.7 (95% CI: 1.32–5.7)). Analysis of MGMT promoter methylation comparing primaries and different metastases over the clinical course revealed no statistical difference (P=0.49).

Conclusions:

In advanced melanoma MGMT promoter, methylation correlates with tolerance of therapy, but not with clinical outcome.     

Adenovirus-based strategies enhance antitumor capability through p53-mediated downregulation of MGMT in uveal melanoma

Uveal melanoma (UM) is an intractable disease with a low survival rates, despite adequate local treatment, as a result of its metastatic characteristics. Thus, new therapeutic strategies, including combinations of novel gene therapy and traditional chemotherapy, are under investigation to improve long-term prognosis. Dacarbazine or DTIC, an alkylating agent which results in DNA methylation, is most commonly used to treat melanoma but the response is very limited. The O6-methylguanine DNA methyl transferase (MGMT), a DNA repair protein, is involved in chemoresistance in DTIC treatment. We previously investigated a combination of oncolytic adenovirus H101 and the alkylating agent DTIC in the treatment of UM cells in vitro and observed a synergistic antitumor effect. In this study, we validated this result and report an enhanced therapeutic effect in vivo. Our findings also demonstrated that the oncolytic adenovirus H101 decreased MGMT levels via accumulation of p53 overcoming DTIC chemoresistance. Therefore, the clinical therapeutic efficacy of DTIC in the treatment of UM might be improved using this adenovirus-based combination therapy.     

Surgical management of liver metastases from uveal melanoma: 16 years' experience at the Institut Curie

Background

Uveal melanoma is characterised by a high prevalence of liver metastases and a poor prognosis.

Aim

To review the evolving surgical management of this challenging condition at a single institution over a 16-year period.

Patients and Methods

Between January 1991 and June 2007, among 3873 patients with uveal melanoma, 798 patients had liver metastases. We undertook a detailed retrospective review of their clinical records and surgical procedures. The data was evaluated with both uni- and multivariate statistical analysis for predictive survival indicators.

Results

255 patients underwent surgical resection. The median interval between ocular tumour diagnosis and liver surgery was 68 months (range 19–81). Liver surgery was either microscopically complete (R0; n = 76), microscopically incomplete (R1; n = 22) or macroscopically incomplete (R2; n = 157). The median overall postoperative survival was 14 months, but increased to 27 months when R0 resection was possible.With multivariate analysis, four variables were found to independently correlate with prolonged survival: an interval from primary tumour diagnosis to liver metastases >24 months, comprehensiveness of surgical resection (R0), number of metastases resected (≤4) and absence of miliary disease.

Conclusions

Surgical resection, when possible, is able to almost double the survival and appears at present the optimal way of improving the prognosis in metastatic uveal melanoma. Advances in medical treatments will be required to further improve survival.     

Temozolomide- and fotemustine-induced apoptosis in human malignant melanoma cells: response related to MGMT, MMR, DSBs, and p53

Malignant melanomas are highly resistant to chemotherapy. First-line chemotherapeutics used in melanoma therapy are the methylating agents dacarbazine (DTIC) and temozolomide (TMZ) and the chloroethylating agents BCNU and fotemustine. Here, we determined the mode of cell death in 11 melanoma cell lines upon exposure to TMZ and fotemustine. We show for the first time that TMZ induces apoptosis in melanoma cells, using therapeutic doses. For both TMZ and fotemustine apoptosis is the dominant mode of cell death. The contribution of necrosis to total cell death varied between 10 and 40%. The O⁶-methylguanine-DNA methyltransferase (MGMT) activity in the cell lines was between 0 and 1100 fmol mg⁻¹ protein, and there was a correlation between MGMT activity and the level of resistance to TMZ and fotemustine. MGMT inactivation by O⁶-benzylguanine sensitized all melanoma cell lines expressing MGMT to TMZ and fotemustine-induced apoptosis, and MGMT transfection attenuated the apoptotic response. This supports that O⁶-alkylguanines are critical lesions involved in the initiation of programmed melanoma cell death. One of the cell lines (MZ7), derived from a patient subjected to DTIC therapy, exhibited a high level of resistance to TMZ without expressing MGMT. This was related to an impaired expression of MSH2 and MSH6. The cells were not cross-resistant to fotemustine. Although these data indicate that methylating drug resistance of melanoma cells can be acquired by down-regulation of mismatch repair, a correlation between MSH2 and MSH6 expression in the different lines and TMZ sensitivity was not found. Apoptosis in melanoma cells induced by TMZ and fotemustine was accompanied by double-strand break (DSB) formation (as determined by H2AX phosphorylation) and caspase-3 and -7 activation as well as PARP cleavage. For TMZ, DSBs correlated significantly with the apoptotic response, whereas for fotemustine a correlation was not found. Melanoma lines expressing p53 wild-type were more resistant to TMZ and fotemustine than p53 mutant melanoma lines, which is in marked contrast to previous data reported for glioma cells treated with TMZ. Overall, the findings are in line with the model that in melanoma cells TMZ-induced O⁶-methylguanine triggers the apoptotic (and necrotic) pathway through DSBs, whereas for chloroethylating agents apoptosis is triggered in a more complex manner.     

Gene expression profiling identifies tumour markers potentially playing a role in uveal melanoma development

Microarray is a powerful tool to compare the gene expression of different tumour specimens and cell lines simultaneously and quantitatively. To get a better insight into genes that are involved in uveal melanoma tumorigenesis, we compared the gene expression profiles of 12 different uveal melanoma cell lines with three melanocyte cell cultures obtained from healthy donor eyes. Gene expression profiles were obtained by nylon filter arrays, containing 1176 gene spots related to cancer development. The expression levels of selected genes were validated on cell lines and primary uveal melanomas by real time RT-PCR, and were subsequently included in cluster analysis. Four candidate tumour markers, Laminin Receptor 1, Endothelin 2, Von Hippel Lindau Binding protein 1 and Cullin 2, have been selected from genes that were differentially expressed in the uveal melanoma cell lines compared to the normal uveal melanocytes. In primary uveal melanomas, these four markers could discriminate between two classes of uveal melanoma, which may be indicative of a differential disease process.     

Increased chondroitin sulphate proteoglycan expression (B5 immunoreactivity) in metastases of uveal melanoma

Background: Metastatic uveal melanoma has a poor prognosis andlimited therapeutic options. Proteoglycans are involved in tumorcell invasion and metastatic behavior. The mAbB5 stains a chondroitinsulphate proteoglycan (CSPG) on cutaneous melanoma cells. Here,we compare the B5-staining of CSPG in primaries and metastasesof uveal melanoma. Material and methods: Immunohistopathological staining was performedin 15 cutaneous and 39 uveal melanoma samples. A score for intracellularand surface staining was established. B5 staining was comparedin primaries and metastases of uveal melanoma using Student'st-test. Results: Eight of 11 (73%) uveal melanoma metastases were positivefor B5-staining whereas only 5 of 28 (18%) primary uveal melanomasamples were B5-positive (P < 0.001). Nine of 15 cutaneousmelanoma samples (60%) were B5-positive without significantdifference between primary and metastatic lesions. Surface stainingwas found both on uveal melanoma metastases and cutaneous melanomas. Conclusions: CSPG was expressed significantly more often inmetastases than in primaries of uveal melanoma. It potentiallymay be one factor associated with metastatic spread. Furtherstudies are needed to determine its use as prognostic factor.The mAbB5 may also be a promising tool for immunotherapy dueto its strong staining of CSPG on the surface of cutaneous andmetastatic uveal melanoma cells. Key words: uveal melanoma, ocular melanoma, chondroitin sulphate proteoglycan, immunotherapy, immunohistochemistry     

Expression and prognostic significance of iNOS in uveal melanoma

Uveal melanoma (UM) is the most common primary intraocular tumor in adults. Disease metastasis occurs in half of the patients and is uniformly fatal despite systemic therapy. Inducible nitric oxide synthase (iNOS) is associated with disease progression in various malignancies including cutaneous melanoma. In this retrospective cohort, we examined the prognostic value of iNOS in UM by performing immunohistochemistry on paraffin‐embedded sections of primary tumors (90 patients) and matched primary and metastatic hepatic tumors (19 patients) with complete histopathological and clinical data. We show that iNOS is expressed in UM (57% of the patients) and high iNOS levels significantly (p = 0.04; hazard ratio (HR) = 2.3) predict disease‐specific survival (DSS) as assessed by Kaplan‐Meier analysis and univariate Cox's proportional hazards regression model. Furthermore, high iNOS expression in the UM primary tissue was significantly associated with metastatic disease and vice versa. Expression of iNOS in hepatic metastases significantly (p = 0.02) predicted a shortened survival as assessed by Kaplan‐Meier analysis. However, iNOS did not appear to be a significant (p = 0.16; HR = 1.9) factor in the multivariate Cox's regression analysis performed together with the clinical parameters tumor diameter, tumor cell type, and tumor location in which only tumor diameter predicted DSS. In conclusion, iNOS predicts DSS in UM and may play a role in disease progression but it is not an independent prognostic factor.     

Local environmental influences on uveal melanoma: vitreous humor promotes uveal melanoma invasion, whereas the aqueous can be inhibitory

BACKGROUND: Uveal melanomas of the choroid and ciliary body are aggressive tumors causing the death of approximately 50% of patients. In contrast, iris melanomas only infrequently metastasize; why these differences exist is not known. The local environment can regulate cancer growth and development, and it is probable the aqueous and vitreous humors have an important role in regulating uveal melanoma behavior. METHODS: To explore this possibility cultures of uveal melanoma were exposed to aqueous and vitreous and the effects investigated using invasion and proliferation assays. ChemiArrays (Chemicon International, Temecula, Calif) were performed to determine which regulatory factors might influence the process. RESULTS: The vitreous universally promoted uveal melanoma invasion, whereas the aqueous mainly had no effect or was inhibitory. Tumor location, and the baseline invasion of the melanoma, affected the ability of aqueous and vitreous from different patients to regulate invasive behavior. Proliferation was not significantly altered as a result of exposure to the aqueous or vitreous. The ability of the humors to regulate uveal melanomas may involve TIMP-2, TIMP-3, and TGF-beta2, as high expression was found by ChemiArray analysis and there were differences in the levels of the regulators in the aqueous compared with the vitreous. CONCLUSIONS: The findings suggest that in situ uveal melanoma development reflects an interaction between the tumor and the environment of the eye. Exposure to the aqueous would therefore contribute to the benign nature of iris melanomas, whereas potential interaction with the vitreous appears to promote the aggressive behavior of posterior uveal melanomas.     

Relationship of uveal and cutaneous malignant melanoma in persons with multiple primary tumors

Uveal and cutaneous melanomas differ in tumor biology, immunophenotypes and the demographic correlates of their occurrence. As a means to examine the possibility of some shared etiologic factors, we wished to learn if the 2 cancers occurred in the same individual more often than would be expected by chance. Data from the Surveillance, Epidemiology and End Results (SEER) program from 1973-1998 were utilized for this purpose. The number of persons who went on to develop a second melanoma was compared to that expected based on the incidence of each type of melanoma in the general population, after adjusting for age, sex, calendar year and residence. Given an initial cutaneous melanoma, there was a 10-fold increased risk of developing a second cutaneous melanoma (95% confidence interval [CI] = 9.4-10.6). Persons with uveal melanoma went on to develop cutaneous melanoma 4.6 times (95% CI = 2.9-6.8) more often than the population at large. In contrast, persons with cutaneous melanoma were not subsequently diagnosed with uveal melanoma at an appreciably elevated rate (standardized incidence ratio [SIR] = 1.4; 95% CI = 0.5-3.0). While these data offer some support for the hypothesis that uveal and cutaneous melanomas have 1 or more etiologies in common, the lack of symmetry in the pattern of second uveal and second cutaneous melanomas remains unexplained.     

Oncogenic GNAQ mutations are not correlated with disease-free survival in uveal melanoma

Background:

Recently, oncogenic G protein alpha subunit q (GNAQ) mutations have been described in about 50% of uveal melanomas and in the blue nevi of the skin.

Methods:

GNAQ exon 5 was amplified from 75 ciliary body and choroidal melanoma DNAs and sequenced directly. GNAQ mutation status was correlated with disease-free survival (DFS), as well as other clinical and histopathological factors, and with chromosomal variations detected by FISH and CGH.

Results:

Of the 75 tumour DNA samples analysed, 40 (53.3%) harboured oncogenic mutations in GNAQ codon 209. Univariate and multivariate analysis showed that GNAQ mutation status was not significantly correlated with DFS.

Conclusion:

The GNAQ mutation status is not suitable to predict DFS. However, the high frequency of GNAQ mutations may render it a promising target for therapeutic intervention.     

Absence of the MGMT protein as well as methylation of the MGMT promoter predict the sensitivity for temozolomide

Background:

The DNA repair protein O⁶-methylguanine-DNA methyltransferase (MGMT) can cause resistance to the alkylating drug temozolomide (TMZ). The purpose of this study was to determine the relationship between the MGMT status, determined by means of several techniques and methods, and the cytotoxic response to TMZ in 11 glioblastoma multiforme (GBM) cell lines and 5 human tumour cell lines of other origins.

Methods:

Cell survival was analysed by clonogenic assay. The MGMT protein levels were assessed by western blot analysis. The MGMT promoter methylation levels were determined using methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) and quantitative real-time methylation-specific PCR (qMSP). On the basis of the results of these techniques, six GBM cell lines were selected and subjected to bisulphite sequencing.

Results:

The MGMT protein was detected in all TMZ-resistant cell lines, whereas no MGMT protein could be detected in cell lines that were TMZ sensitive. The MS-MLPA results were able to predict TMZ sensitivity in 9 out of 16 cell lines (56%). The qMSP results matched well with TMZ sensitivity in 11 out of 12 (92%) glioma cell lines. In addition, methylation as detected by bisulphite sequencing seemed to be predictive of TMZ sensitivity in all six cell lines analysed (100%).

Conclusion:

The MGMT protein expression more than MGMT promoter methylation status predicts the response to TMZ in human tumour cell lines.     

Association of specific chromosome alterations with tumour phenotype in posterior uveal melanoma

Posterior uveal melanomas have recurrent alterations of chromosomes 1, 3, 6 and 8. In particular, changes of chromosomes 3 and 8 occur in association, appear to characterize those tumours with a ciliary body component, and have been shown to be of prognostic significance. The relevance of other chromosome alterations is less certain. We have performed cytogenetic analysis on 42 previously untreated primary posterior uveal melanomas. Of interest was the observation that as tumour size increased the involvement of specific chromosome changes, and the amount of chromosome abnormalities likewise increased. Loss, or partial deletions, of the short arm of chromosome 1 were found to associate with larger ciliary body melanomas; typically, loss of the short arm resulted from unbalanced translocations, the partners of which varied. Trisomy of chromosome 21 occurred more often in ciliary body melanomas, whilst rearrangements of chromosomes 6 and 11 were primarily related to choroidal melanomas. Our results imply that alterations of chromosome 1 are important in the progression of some uveal melanomas, and that other chromosome abnormalities, besides those of chromosomes 3 and 8, are associated with ocular tumours of particular locations.     

SUMOylation regulates Rb hyperphosphorylation and inactivation in uveal melanoma

Small ubiquitin‐like modifier (SUMO)ylation is one of the posttranslational modifications and is implicated in many tumor types. Modulation of SUMOylation can affect tumor progression, but the underlying mechanisms remain unclear. Here, we show that, for the first time, in uveal melanoma (UM), the most common intraocular malignancy in adults, global SUMOylation is upregulated and participates in tumor growth. Inhibition of SUMOylation in UM is sufficient to reduce tumor growth both in vitro and in vivo. Furthermore, we found that retinoblastoma protein (Rb) is a target protein and a critical downstream effector of the upregulated SUMOylation activity in UM. Increased SUMOylation of the Rb protein leads to its hyperphosphorylation and inactivation in UM cells, promoting UM cell proliferation. In summary, our results provide novel insight into the mechanism underlying SUMOylation‐regulated tumor growth in UM.     

Episodic Src activation in uveal melanoma revealed by kinase activity profiling

Background:

The RAS/RAF/MEK/ERK pathway is involved in the balance between melanocyte proliferation and differentiation. The same pathway is constitutively activated in cutaneous and uveal melanoma (UM) and related to tumour growth and survival. Whereas mutant BRAF and NRAS are responsible for the activation of the RAS/RAF/MEK/ERK pathway in most cutaneous melanoma, mutations in these genes are usually absent in UM.

Methods:

We set out to explore the RAS/RAF/MEK/ERK pathway and used mitogen-activated protein kinase profiling and tyrosine kinase arrays.

Results:

We identified Src as a kinase that is associated with ERK1/2 activation in UM. However, low Src levels and reduced ERK1/2 activation in metastatic cell lines suggest that proliferation in metastases can become independent of Src and RAS/RAF/MEK/ERK signalling. Inhibition of Src led to the growth reduction of primary UM cultures and cell lines, whereas metastatic cell line growth was only slightly reduced.

Conclusion:

We identified Src as an important kinase and a potential target for treatment in primary UM. Metastasis cell lines seemed largely resistant to Src inhibition and indicate that in metastases treatment, a different approach may be required.     

NSCLC患者血浆p16和MGMT基因甲基化检测及临床意义

目的：检测非小细胞肺癌（non—small cell lung cancer，NSCLC）患者外周血血浆中p16基因、O^6-甲基乌嘌呤-DNA甲基转移酶（O^6-methylguanine—DNA methyhransferase，MGMT）基因启动子的甲基化状态，探讨p16、MGMT基因启动子的异常甲基化在NSCLC筛查及早期诊断中的意义。方法：利用巢式甲基化特异性聚合酶链反应法检测NSCLC患者外周血血浆p16、MGMT基因启动子的甲基化状态。结果：65例NSCLC血浆样品中分别发现19例（29．23％）p16基因启动子异常甲基化和16例（24．62％）MGMT基因启动子异常甲基化，45例正常对照血浆组未检测到p16、MGMT基因启动子的异常甲基化（P〈0．05），血浆中两基因甲基化检出率与NSCLC的分型及临床分期无明显相关性（P〉0．05）。结论：利用巢式甲基化特异性PCR法检测外周血血浆中p16、MGMT基因启动子的甲基化，可为NSCLC的筛查、早期诊断及预后判断提供有价值的信息。     

Nuclear HER3 is associated with favorable overall survival in uveal melanoma

HER3 is a member of the epidermal growth factor receptor (EGFR) family and is expressed in several types of cancer. Both the cytoplasmic and nuclear appearances of the receptor have been reported. Here, we investigate the expression and subcellular distribution of HER3 in uveal melanoma (UM) cells and tissues and its potential impact on clinical outcome of patients. Paraffin-embedded samples from 128 consecutive UM patients, enucleated without alternative treatment on UM diagnosis, were evaluated for HER3 using immunohistochemistry. Immunoreactivity was scored for frequency, intensity of positive cells, and subcellular distribution. The results were correlated with the established clinicopathological parameters using univariate and multivariate statistical analyses. HER3 expression was shown in 70% of the cases (89/128). This contrasts with the other EGFR family receptors (EGFR, HER2 and HER4) that are infrequently expressed in UM. Surprisingly, HER3 was found to be localized solely in the cell nuclei in 56 cases. The remaining 33 HER3 positive cases showed diffuse distribution (cytoplasmic ± nuclear). Nuclear HER3 was independently correlated with a more favorable overall survival (p = 0.043 and hazard ratio = 0.618) compared to cases with diffuse and/or no HER3. Nuclear localization of HER3 was also confirmed in fresh UM material and in UM cell lines. In conclusion, HER3 is frequently localized solely in the cell nuclei in UM and as such it predicts a more favorable overall survival.