Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.10.3.1 (tyrosinase)
9,065 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The presence of regional lymph node metastases is one of the most significant prognostic factors for predicting survival in patients with clinical stage I or II cutaneous melanoma. For accurate staging of the primary tumor a sensitive technique is required to detect occult nodal micrometastases. This prospective diagnostic study was designed to evaluate the incidence of nodal micrometastases using nested reverse transcription-polymerase chain reaction (RT-PCR) for tyrosinase in comparison to immunohistochemical examination. Furthermore, the incidence of melanoma micrometastases detected by RT-PCR was analysed in correlation to major prognostic factors. A total of 466 regional lymph nodes from 79 patients with primary cutaneous melanoma (tumor thickness > 0.75 mm) were investigated. In 49 lymph nodes from 31 patients immunohistochemistry demonstrated melanoma metastases. Using tyrosinase RT-PCR, nodal micrometastases were detected in 136 lymph nodes from 52 patients including all lymph nodes positive by immunohistochemical examination. Out of the 417 lymph nodes negative by immunohistochemistry, 87 nodes (21%) were identified to express tyrosinase by the RT-PCR technique. Among the 48 patients negative by immunohistochemical assessment, 21 (44%) had nodal micrometastases (n = 40) using RT-PCR. All 68 lymph nodes from 46 non-melanoma patients serving as negative controls for tyrosinase RT-PCR were negative. The detection of melanocytic nodal micrometastases by tyrosinase RT-PCR is a highly specific method with a sensitivity significantly higher than that achieved by immunohistochemistry (p < 0.0001). Patients with nodal micrometastases identified exclusively by RT-PCR had significantly higher tumor thickness as compared to patients with negative results by RT-PCR (p < 0.01).
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PMID:Lymph node micrometastases of cutaneous melanoma: increased sensitivity of molecular diagnosis in comparison to immunohistochemistry. 969 21

The sentinel node has been reported to be representative for the presence or absence of metastatic melanoma in the draining lymph node basin. In this study, for the first time sentinel nodes and adjoining nonsentinel nodes were analyzed for micrometastatic disease using tyrosinase reverse transcription-polymerase chain reaction (RT-PCR) in comparison with standard immunohistochemistry. Successful identification of the sentinel nodes using a gamma probe-guided surgery was achieved in 73 (92%) of 79 patients with cutaneous stage I and II melanoma (tumor thickness > or =0.75 mm). A total of 794 regional lymph nodes, 148 sentinel nodes, and 646 adjoining nonsentinel nodes were evaluated. Tyrosinase RT-PCR was shown to increase the sensitivity for melanoma cell detection in sentinel nodes significantly (49% positivity) as compared with immunohistochemistry using antibodies against HMB-45 antigen and S-100 protein (18% positivity). Examination of sentinel nodes was highly predictive in determining the presence of regional lymph node micrometastasis by immunohistochemistry (99%) and RT-PCR (89%). Interestingly, detection of nodal micrometastasis by RT-PCR showed a strong positive correlation with tumor thickness of primary cutaneous melanoma. These results suggest the clinical significance and emphasize the importance of tyrosinase RT-PCR for detection of melanoma micrometastasis in sentinel nodes.
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PMID:Detection of melanoma micrometastasis in sentinel nodes by reverse transcription-polymerase chain reaction correlates with tumor thickness and is predictive of micrometastatic disease in the lymph node basin. 1040 6

Histopathologic parameters of the primary tumor, such as Breslow's tumor thickness and Clark's level of invasion are the current basis for prognostic classifications of primary cutaneous melanoma. Once patients develop regional node metastasis, histopathologic features of the primary melanoma no longer contribute significantly to survival prediction. In this tumor stage, the extent of lymph node involvement is the main prognostic factor. This study addresses the question whether application of a highly sensitive molecular biology assay for detection of submicroscopic melanoma cells in sentinel lymph nodes may be suitable to improve melanoma staging. One hundred and sixteen patients with primary cutaneous melanoma with a total of 214 sentinel lymph nodes were enrolled. Sentinel lymph nodes were analyzed by histopathology including immunohistochemistry and by reverse transcription-polymerase chain reaction for tyrosinase. Patients were examined for tumor recurrences during a follow-up period of 19 mo (median). Disease-free survival probabilities were calculated and independent prognostic factors were determined by multivariate analysis. Using histopathology, micrometastatic nodal involvement was detected in 15 patients (13%). Of the 101 patients with histopathologically negative sentinel lymph nodes, 36 were reclassified by positive tyrosinase reverse transcription-polymerase chain reaction and 65 patients were still negative by reverse transcription-polymerase chain reaction. Recurrences were observed in 23 (20%) of 116 patients. These tumor recurrences were demonstrated in 10 patients (67%) with histopathologically positive sentinel lymph nodes, in nine patients (25%) with submicroscopic tumor cells detected by reverse transcription-polymerase chain reaction, and in four patients (6%) negative by both methods. The differences in recurrence rates were statistically significant (p = 0.01). In a multivariate analysis, histopathologic and reverse transcription-polymerase chain reaction status of the sentinel lymph node were demonstrated to be the only significant prognostic factors for predicting disease-free survival. Tyrosinase reverse transcription-polymerase chain reaction for the detection of minimal residual melanoma in sentinel lymph nodes is a powerful tool to determine patients who are at increased risk for subsequent metastasis. Moreover, a group of patients with high tumor thickness was identified by negative reverse transcription-polymerase chain reaction to be at low risk for recurrent disease. These data may have an impact on future tumor classifications of primary cutaneous melanoma.
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PMID:Examination of regional lymph nodes by sentinel node biopsy and molecular analysis provides new staging facilities in primary cutaneous melanoma. 1073 66

Advances in the understanding of the biology and treatment of melanoma have moved the care of melanoma patients into an increasingly multidisciplinary environment. Surgeons must understand these advances because they will often be responsible for directing the overall care of these patients. Most patients with melanomas more than 1 mm in diameter and no evidence of metastatic disease should be offered SLNB to more accurately stage them and direct decisions about participation in postoperative adjuvant therapy trials. Until the results of the MSLT are known, the effect of SLNB and ELND on outcome remains unknown. SLNs should be analyzed with serial sectioning and immunohistochemistry to avoid missing micro-metastatic disease. Based on the results of the ECOG-1684 trial, the FDA approved IFN-alpha 2b for the adjuvant treatment of melanoma patients with thick primary tumors (> 4 mm) or resected nodal disease. IFN-alpha 2b treatment is expensive and potentially toxic. The data from ECOG-1684 do not support the use of IFN-alpha 2b in patients with node-negative disease. In light of the ECOG-1690 trial results, the role of high-dose IFN-alpha 2b in the management of patients with resected nodal disease is considerably less clear. Any recommendations for treatment with high-dose IFN-alpha 2b should be made only after weighing the costs, side effects, and potential benefits for individual patients. Numerous, less toxic, promising, adjuvant immunotherapeutic strategies have been developed and are being tested in multicenter, prospective, randomized trials. These strategies include GMK, PMCV, and Melacine. If the results of any of these trials show a survival advantage compared with placebo or equivalent survival compared with IFN-alpha 2b, these immunotherapeutic agents will become the adjuvant treatment of choice for patients with resected high-risk melanoma. RT-PCR detection of tyrosinase in SLNs can identify patients with submicroscopic nodal disease who may be at increased risk for recurrence or death from melanoma. An ongoing, prospective, randomized trial will determine whether patients with histologically negative but RT-PCR-positive SLNs will benefit from lymphadenectomy or adjuvant IFN-alpha 2b therapy. RT-PCR can also identify minimal residual disease in peripheral blood and bone marrow from patients with high-risk melanoma, but RT-PCR analysis of peripheral blood and bone marrow is still experimental, and procedural details need to be standardized and prospectively validated in large patient groups before its use can be considered the standard of care.
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PMID:Melanoma. A multidisciplinary approach for the general surgeon. 1083 8

Various histopathological techniques have been developed in order to improve the detection of micrometastasis in the regional lymph nodes of patients with malignant melanoma. Our standard histopathological examination of lymph nodes included haematoxylin and eosin (H & E) staining and immunohistochemistry (IH) using antibodies to HMB-45 and S-100 proteins of three paraffin sections at one level. In addition, lymph nodes were examined by molecular biological methods using tyrosinase reverse transcription-polymerase chain reaction (RT-PCR). In this study, we investigated the use of step sections and IH in lymph nodes regarded as negative by standard histopathology but positive by tyrosinase RT-PCR, suggesting the presence of tumour cells. In a series of 76 consecutive patients with stage I and II cutaneous melanoma, a total of 156 regional lymph nodes were examined by H & E staining, IH and tyrosinase RT-PCR. All lymph nodes were bisected along their long axis for separate evaluation. In 21 patients, at least one lymph node in the regional nodal basin reported as tumour-negative by standard histopathology was demonstrated to express tyrosinase (total number of nodes = 33). These 33 lymph nodes were re-examined by H & E and IH at 10 additional levels of the paraffin block. Only one lymph node from one patient had occult melanoma cells in deeper levels detected exclusively by IH. Six out of 20 patients with positive findings exclusively on tyrosinase RT-PCR developed tumour recurrences during a median follow-up of 34 months. We therefore conclude that additional step sectioning with IH does not significantly increase the detection of tumour-positive lymph nodes. Patients with melanoma cells detected exclusively by RT-PCR, however, were shown to be at increased risk for tumour recurrence.
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PMID:Does intensive histopathological workup by serial sectioning increase the detection of lymph node micrometastasis in patients with primary cutaneous melanoma? 1125 16

Sentinel node (SN) mapping and biopsy seems at present the best way to assess the nodal status in cutaneous melanoma without removing the lymphatic chain. The procedure is minimally invasive, safe and low cost, and allows selection of patients who can benefit from elective node dissection. From March 1997 up to July 1999 we examined 112 SNs excised after lymphatic mapping from 95 patients (48 males and 47 females) with stage I cutaneous melanoma affecting the trunk or limbs. Of these, 88 SNs from 74 patients were submitted to polymerase chain reaction (PCR) in order to detect tyrosinase mRNA. A new antibody (anti-tyrosinase, Clone T311, IgG2a type, Lab Vision Corporation) was used to detect nodal micrometastases. The search for micrometastases was histologically positive in 15 SNs and negative in 97. The 88 SNs examined using molecular biology were positive in 40 cases and negative in 48. In 28 only the PCR was positive. The new antibody used to detect micrometastases was shown to be very useful. Cases positive on both conventional histology and PCR were Clark level II or more and were thicker than 0.6 mm. No difference with regard to site or sex was observed. Lymphoedema and hypersensitivity reactions, nor the inability to work, did not occur. Only patients with histologically proven micrometastases underwent elective node dissection. Cases positive only on molecular biology were submitted to close follow-up.
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PMID:Detection of nodal micrometastases using immunohistochemistry and PCR in melanoma of the arm and trunk. 1193 Jan 11

Nodal nevi represent a potential diagnostic pitfall in the analysis of lymph nodes. They may be confused with metastatic melanoma or carcinoma. Although several morphologic guidelines exist for the recognition of nodal nevi, on occasion immunohistochemical studies may be helpful for diagnosis, especially when melanocytes extend into the lymph node parenchyma. To learn more about the immunohistochemical profile of nodal nevi we examined 15 nodal nevi for the expression of S-100 protein, gp100 (HMB-45), Melan-A/MART-1 (A103), and tyrosinase (T311), and we studied the expression of Ki-67 (MIB-1) in nodal nevi and 40 melanoma metastases (35 lymph node and five cutaneous metastases). All nodal nevi were homogeneously immunoreactive for S-100 protein, tyrosinase, and Melan-A/MART-1. Two nodal nevi were focally positive for gp100. Fourteen of 15 nodal nevi were completely negative for Ki-67. One large cellular nodal nevus showed nuclear labeling in <0.2% of melanocytes. All metastases showed MIB-1 labeling. However, the percentage of labeled tumor cells varied widely, ranging from 2% to 80%. These results demonstrate that MIB-1 and HMB-45 are helpful reagents for the distinction of nodal nevi from melanoma. Immunohistochemistry for S-100 protein, Melan-A/MART-1, or tyrosinase facilitates the recognition of melanocytes but does not distinguish between nodal nevus and metastatic melanoma.
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PMID:Expression of melanocyte differentiation antigens and ki-67 in nodal nevi and comparison of ki-67 expression with metastatic melanoma. 1236 50

Molecular staging of cancers hold the promise of being more accurate compared with routine histology, particularly with regard to determining regional-nodal status. With newer reverse transcriptase-PCR (RT-PCR)-based assays, sensitivities reported are as high as identifying one cancer cell in a background of a million normal cells. Although this sensitivity is 100-times what the human eye can differentiate under the microscope, the new challenge becomes determining the relevance of this low-volume disease in the regional basin, in particular, the sentinel lymph node (SLN). Patients with melanomas greater than 0.75 mm in tumor thickness participated in a research study that examined their SLNs with routine histology, immunhistochemical staining and a RT-PCR assay based on the tyrosinase probe. A total of 311 patients were involved in the study and patients whose SLN were negative from all three assays for metastatic disease had a good survival, with a 92% disease-free survival (DFS) and a 97% overall survival (OS) regardless of the tumor thickness or the ulceration status of the primary melanoma. Patients upstaged with the RT-PCR assay had a significantly decreased DFS and OS compared with patients who were SLN negative. Patients who had enough tumor burden in the SLN that allowed their metastatic disease to be identified with routine histology had a 48% recurrence rate at 5 years. A recently published meta-analysis confirmed that molecular staging of the SLN in melanoma contains important prognostic information. Micrometastatic disease missed by routine histology in the SLN in melanoma patients is clinically relevant disease. Molecular staging has the potential of providing a more accurate staging in the SLN, for prognostication and directing adjuvant therapies.
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PMID:Molecular staging for patients with malignant melanoma. 1802 Sep 32

Nineteen patients with stage IV melanoma were treated in an escalating dose, phase 1 trial of a DNA plasmid vaccine pSEM. The plasmid encoded T-cell epitopes from differentiation antigens Melan-A/melanoma antigen recognized by T cells (MART)-1 and tyrosinase, encompassing amino acids 26-35 and 31-70 from Melan-A/MART-1, and 1-9 as well as 369-377 from tyrosinase. End points of the trial were safety, tolerability, and melanoma antigen-specific immunity by tetramer assay. Intralymph nodal infusions of the vaccine were given 4 times, every 2 weeks over 96 hours each to groin lymph nodes. Vaccine doses were 500, 1000, and 1500 microg of DNA per infusion. Disease evaluation was performed 8 weeks after treatment initiation. The vaccine was well tolerated, with only grade I/II toxicity observed and no dose limiting toxicity at the highest dose of 1500 microg per infusion. Immune response defined prospectively was seen in 4/19 patients, and 5/19 had evidence of preexisting immunity to Melan-A/MART-1. No immune responses to tyrosinase was seen. There was a correlation between time to progression (TTP) and Melan-A/MART-1 immunity (preexisting or induced) for all patients. There was no association between TTP and immune competence assayed by ex vivo polyclonal stimulation of peripheral blood mononuclear cells. No clinical responses were seen. DNA plasmid pSEM vaccine was well tolerated when administered intranodally by 96-hour infusion to patients with stage IV melanoma, and was immunogenic, but did not induce regression of established disease. The association of TTP with preexisting or induced Melan-A immunity supports future attempts to induce potent immunity to this antigen.
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PMID:Phase 1 trial of intranodal injection of a Melan-A/MART-1 DNA plasmid vaccine in patients with stage IV melanoma. 1848 91

Evidence for the in vitro lymphocyte response against autologous melanoma has been accumulating over the past 10 years, leading to the identification of numerous melanoma-associated antigens recognised by T cells. These antigens are targets for specific immunotherapy protocols. However, their expression is heterogeneous during tumour progression and may contribute to therapeutic escape mechanisms and disease progression. This study was designed to chart the importance of these escape mechanisms, and to assess the relationship between gene expression and the clinical profile (especially survival data) of patients with melanoma. We studied the expression of certain melanoma genes in tissue biopsies from 202 patients using reverse transcriptase-polymerase chain reaction (RT-PCR). The evaluated genes were Melan-A, tyrosinase, Na-17A, MAGE-1, MAGE-3 and Ny-ESO-1. We then correlated the results to the patients' survival data. 202 samples (cutaneous, nodal and visceral biopsies) were analysed by RT-PCR. No relationship was found between clinical data and gene expression. No relationship was found between survival data and gene expression, when samples of all stages were combined in the analysis. However, interactions between gene expression and disease stage were significant. When stage III samples alone were considered, MAGE-3 expression alone or in association with the expression of the other tumour-specific genes was found to be significantly associated with a higher disease-free survival (respectively, P = 0.0349; 0.007). Our results provided no evidence for a relationship between gene expression and clinical data, or between gene expression and survival data. However, with regard to certain sub-groups, such as stage III samples, tumour gene expression was significantly associated with survival.
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PMID:Melanoma gene expression and clinical course. 1932 32


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