Detection of melanoma cells in peripheral blood by means of reverse transcriptase and polymerase chain reaction

Detection of Circulating Prostate Cancer Cells Using Real Time Rt – Pcr: Our Experience

PCR (Polymerase Chain Reaction) has revolutionized molecular genetics and continues to be applied to many fields of medicine and biology. We used nested real time RT – PCR to detect circulating prostate cells in patients affected by prostate cancer, in order to evaluate a possible clinical role of this technique. We present our initial experience.

New developments in the staging of melanoma

As the incidence of melanoma increases, so does the search for new staging techniques that may provide important prognostic information and aid in the detection of early metastatic disease. The application of molecular techniques may provide powerful new tools in this search. This review summarizes recent findings obtained by means of conventional RT-PCR, cDNA arrays, and proteomics in the investigation of human melanoma. The molecular tools discussed in this review demonstrate how global transcript and protein analysis might contribute not only to the staging of melanoma, but may hold great promise in improving the diagnosis and treatment of this disease.

RT-PCR tyrosinase expression in the peripheral blood of melanoma patients

Controversial data are reported in the literature concerning the role of peripheral blood tyrosinase messenger RNA reverse transcription PCR analysis in melanoma patient management. Some papers assess the clinical relationship between tyrosinase expression and disease outcome, while others address the high degree of variability in the positive rate percentage and demonstrate the transient shedding of melanoma cells in the bloodstream. An overview of the current knowledge about the applications and limitations of tyrosinase analysis compared with other biologic markers is presented herein. Tyrosinase expression should not be considered as a tumor burden-related marker in the peripheral blood, but rather as a measure of the potential increased risk of metastatic spreading. In this view, reverse transcription PCR gains a clinical significance when sequential determinations are performed during follow-up, whereas the evaluation of a single sample, either positive or negative, does not bring any additional clinical information.

Prognostic significance of detecting micrometastases by tyrosinase RT/PCR in sentinel lymph node biopsies: lessons from 322 consecutive melanoma patients

This prospective study was performed to determine the prognostic value of tyrosinase mRNA detection in sentinel lymph nodes (SLN) of melanoma patients. About 847 SLNs from 322 consecutive patients were assessed by histopathology and immunohistochemistry as well as tyrosinase-reverse transcriptase-polymerase chain reaction (RT/PCR) for the presence of micrometastases. The results were correlated with the prognostic parameters employing a multivariate analysis after a median follow-up of 37 months. Histopathological analysis revealed metastases in 34/322 patients (10.6%). Among the 288 patients with histopathologically negative SLN, tyrosinase-mRNA was detected in 39 patients. A relapse of the tumour occurred in 44.1% of the patients with histopathologically positive SLN, in 25.6% with histopathologically negative, but tyrosinase-RT/PCR-positive SLN, and 8.0% with "double-negative" SLN. A multivariate analysis identified tumour thickness, the histopathological SLN status, and the ulceration of the primary tumour as independent prognostic factors. Thus, by assessing tyrosinase mRNA in the SLN of melanoma patients, we identified a subgroup with histopathologically negative, but Tyr-RT-PCR-positive SLN who have a high risk of disease relapse.

The Use of Real-Time Reverse Transcription-PCR for Prostate-Specific Antigen mRNA to Discriminate between Blood Samples from Healthy Volunteers and from Patients with Metastatic Prostate Cancer

PURPOSE

A clinical role for nonquantitative reverse transcription-PCR (RT-PCR) using prostate-specific antigen in blood samples from patients with prostate cancer remains undefined. Assay variation and detection of prostate-specific antigen mRNA illegitimate transcription may explain inconsistent results between studies. Defining levels of prostate-specific antigen mRNA expression in blood samples from healthy volunteers and patients with prostate cancer would allow cutoffs to be established to distinguish the two groups.

EXPERIMENTAL DESIGN

Quantitative real-time RT-PCR for prostate-specific antigen mRNA was established and levels of prostate-specific antigen mRNA measured in bloods samples from healthy volunteers (n=21) and patients with localized (n=27) and metastatic (n=40) prostate cancer.

RESULTS

Levels of prostate-specific antigen mRNA were significantly higher in blood samples from patients with metastatic prostate cancer than in blood samples from patients with localized prostate cancer (P <0.001) or in blood samples from healthy volunteers (P <0.01); levels between patients with localized prostate cancer and healthy volunteers were no different. Assay sensitivity to detect patients with metastatic prostate cancer was 68% with specificity of 95%. In patients with newly diagnosed metastatic prostate cancer, monitoring response to hormonal therapy was possible with this assay. No correlation between levels of prostate-specific antigen mRNA and serum prostate-specific antigen protein levels was found, suggesting that prostate-specific antigen mRNA and serum prostate-specific antigen protein levels reflect different features of prostate cancer, i.e., circulating tumor cells and total tumor bulk, respectively.

CONCLUSIONS

Quantitative RT-PCR discriminates patients with metastatic prostate cancer from healthy volunteers and patients with localized prostate cancer but cannot discriminate patients with localized prostate cancer from healthy volunteers. A role for quantitative RT-PCR has been identified in the assessment and monitoring of patients with metastatic prostate cancer.

Detection of Melanoma Cells in Sentinel Lymph Nodes by Reverse Transcriptase-Polymerase Chain Reaction: Prognostic Significance

BACKGROUND

Recently reverse transcriptase-polymerase chain reaction (RT-PCR) has been proposed as a new sensitive method for the detection of submicroscopic melanoma nodal metastases. Sentinel lymph node (SLN) status is considered the most important prognostic factor for melanoma patients. Thus, in recent years, melanoma research has been focused on identifying new molecular markers of micrometastases.

METHODS

In this study, 129 SLNs were collected and analyzed by RT-PCR for tyrosinase and melanoma inhibitory activity (MIA) messenger RNA (mRNA) expression. RESULTS from PCR analysis were then compared with those obtained by hematoxylin and eosin and immunohistochemistry and related to progression of disease.

RESULTS

MIA gene expression was positive by RT-PCR in 27% of the tyrosinase-positive SLNs. When the correlation between tyrosinase and/or MIA mRNA expression and disease-free survival was evaluated by the Kaplan-Meier exact test, there was a statistically significant correlation between simultaneous tyrosinase and MIA gene expression in SLNs and progression of disease.

CONCLUSIONS

RT-PCR analysis for both MIA and tyrosinase mRNA may identify a subset of melanoma patients with a worse prognosis whom the routine methods, such as histology and immunohistochemistry, fail to identify because of the poor sensitivity of these methods.

Ganglioside-based vaccines and anti-idiotype antibodies for active immunotherapy against cancer

This review shall present an update in anticancer ganglioside-based immunotherapies, with particular emphasis on molecular vaccines and anti-idiotype mAbs produced by the Center of Molecular Immunology (Havana, Cuba). The project comprises vaccines of N-acetyl or N-glycolylneuraminic acid GM3 ganglioside incorporated into very small proteoliposomes and anti-idiotype antibodies to glycolylated gangliosides. Development of these vaccine preparations from preclinical models of melanoma, breast and lung cancer to human investigation is summarized. A brief discussion on the progress and limitations of present-day clinical trials and future prospects is also included.

Detection of melanoma cells in the lymphatic drainage after lymph node dissection in melanoma patients by using two-marker reverse transcriptase-polymerase chain reaction assay

BACKGROUND

The aim of this study was to evaluate the role of melanoma gene expression as a marker of the presence of melanoma cells in lymphatic drainage routinely collected after lymphadenectomy and to correlate reverse transcriptase-polymerase chain reaction (RT-PCR) assay results with recurrence, survival, and prognostic factors.

METHODS

We collected 24-hour postoperative lymphatic drainage samples (between days 2 and 4) from 93 patients with stage III melanoma who underwent radical lymphadenectomy between May 2002 and November 2003. We used RT-PCR assays with primers specific for the tyrosinase and MART-1 (Melan-A) genes. The samples were considered positive if at least one marker was expressed. Median follow-up time was 12.8 months.

RESULTS

In 18 (19.4%) of 93 patients, the RT-PCR assay results were positive: in 8 of 18 for tyrosinase only, in 7 of 18 for MART-1 only, and in 3 of 18 for both markers. We observed a significantly higher recurrence rate in patients with positive RT-PCR results (15 of 18; 83%) than negative results (26 of 75; 35%; P = .0001). Positive results of RT-PCR correlated with the number of involved lymph nodes (P = .0001) and extracapsular extension of nodal metastases (P = .03). We observed significant differences in overall and disease-free survival for RT-PCR-positive and -negative patients in univariate and multivariate analyses.

CONCLUSIONS

We observed positive RT-PCR assay results for melanoma cells in the lymphatic drainages of approximately 20% of patients after lymphadenectomy. This correlated significantly with early recurrence and shorter survival. These results may suggest that the RT-PCR assay could be useful for routinely analyzing postoperatively collected lymphatic drainage in stage III melanoma patients and for predicting disease progression.

Quantitative detection of circulating tumor cells in cutaneous and ocular melanoma and quality assessment by real-time reverse transcriptase-polymerase chain reaction

PURPOSE

Inconsistent reports on the detection of melanoma cells in peripheral blood by reverse transcriptase-PCR (RT-PCR) have resulted in uncertainty on the prognostic value of circulating melanoma cells.

EXPERIMENTAL DESIGN

We developed real-time RT-PCR assays for quantitation of tyrosinase, MelanA/MART1, and gp100 and for porphobilinogen deaminase housekeeping gene. Melanoma tissue (n = 18), peripheral blood samples from healthy donors (n = 21), and patients with cutaneous (n = 122) and uveal (n = 64) melanoma from our institution were analyzed. For quality control, an additional 251 samples from ongoing multicenter studies were compared with in-house samples.

RESULTS

Tyrosinase was not detected in healthy donor blood samples. For the two other markers, cutoff values had to be defined to distinct patient samples from controls. Patients with stage IV uveal and cutaneous melanoma expressed all three markers more frequently and at higher levels in peripheral blood as compared with earlier stages. The variation of expression was 4 logs and correlated with tumor load and serum lactate dehydrogenase. In 2 of 3 uveal melanoma patients, detection of circulating tumor cells preceded the development of liver metastases. The diagnostic sensitivity was optimal in blood samples containing >0.1pg/ microl porphobilinogen deaminase (95.7% of in-house samples and 57.4% of multicenter samples).

CONCLUSIONS

Real-time RT-PCR is able to quantitatively define the quality of a sample and provides quantitative data for melanoma markers. Disparities in the results of previous studies may be attributable to undetected differences in sample quality. The prognostic relevance of this assay is currently under evaluation in several prospective randomized trials.

Serial Follow-Up and the Prognostic Significance of Reverse Transcriptase-Polymerase Chain Reaction—Staged Sentinel Lymph Nodes From Melanoma Patients

Purpose

Reverse transcriptase-polymerase chain reaction (RT-PCR) may provide an extremely sensitive method for detection of occult nodal disease. We evaluated the role of a single-marker RT-PCR assay for tyrosinase mRNA in the detection of melanoma sentinel lymph node (SLN) metastases and correlated the results with long-term clinical outcome.

Patients and Methods

One hundred twelve patients who underwent SLN biopsy for melanoma were prospectively analyzed. SLNs were bivalved, with half of each specimen evaluated by histologic methods and the other half evaluated by nested RT-PCR for tyrosinase.

Results

Fifteen patients (13%) had histologically positive SLNs, all of whom were also positive by RT-PCR (HISTO+/PCR+). Thirty-nine patients (35%) had SLNs that were negative by both histology and RT-PCR (HISTO−/PCR−). Fifty-eight patients (52%) were histologically negative but upstaged with a positive RT-PCR result (HISTO−/PCR+). Initially, at a median follow-up of 42 months, recurrence rates among the three cohorts were statistically different (HISTO+/PCR+, 53%; HISTO−/PCR+, 14%; and HISTO−/PCR−, 0%). However, at a longer median follow-up (67 months), recurrence rates for the HISTO−/PCR+ (24%) and HISTO−/PCR− (15%) groups were no longer statistically different (P = .25). The median time to relapse between the HISTO−/PCR+ and HISTO−/PCR− groups differed by 10 months (31 v 41 months, respectively).

Conclusion

With extended follow-up of patients with histologically negative SLNs, detection of submicroscopic disease by tyrosinase RT-PCR does not define a subgroup that is at higher recurrence risk when compared with patients with RT-PCR–negative SLNs. Future studies evaluating molecular staging will require approximately 5 years of median follow-up to accurately define outcome for patients with occult melanoma metastases.

Molecular detection of circulating tumor cells is an independent prognostic factor in patients with high-risk cutaneous melanoma

Detection of circulating tumor cells (CTCs) might improve current staging procedures by identifying a subgroup of patients with minimal residual disease and thus a higher risk of disease recurrence. Forty patients with > or =2-mm-thick cutaneous melanoma with or without lymph node metastasis were enrolled. After standard radical surgery and adjuvant therapy in case of lymph node metastasis, patients were followed up with routine physical and radiologic assessments as well as serial PCR-based analysis of CTCs using 2 melanoma markers (tyrosinase and Melan-A/Mart-1). After a median follow-up of 30 months, 18 patients had disease recurrence and 28 were PCR-positive before the disease became clinically evident. The sensitivity of the molecular test was 83%. Median time to PCR positivity and median PCR-to-relapse time were 12 and 8 months, respectively. At multivariate analysis, PCR positivity was an independent predictor of disease recurrence (hazard ratio=2.06, 95% CI 1.07-3.35; p=0.03). Among high-risk melanoma patients, serial PCR-based analysis of CTCs can identify a subgroup at higher risk of disease recurrence, with clinically significant advance. Therefore, CTC detection might be employed for the selection of patients for adjuvant treatment and during follow-up for early indication of therapeutic failure.

The history and future of melanoma staging

The evolution and progressive refinement of an internationally accepted melanoma staging system over the last 50 years has resulted in much greater accuracy and increased utility, but the staging process has become more complex and less intuitive. This raises the question of whether melanoma staging should continue to develop with ever-increasing levels of complexity, or whether attempts should be made to produce an alternative system that is simpler and more intuitive. The current, TNM-based American Joint Committee on Cancer (AJCC) staging system for melanoma incorporates only some of the prognostic factors of proven significance. However, the information that is now available about these and other, well-documented prognostic factors allows accurate prediction of an individual melanoma patient's prognosis using a computer-generated estimate. Thus an alternative staging strategy that could be considered in the future would be to use such an estimate to obtain a numerical score for each patient, based on all available information agreed to be of prognostic relevance. A stage grouping could then be assigned on the basis of that score, according to previously determined score ranges for each stage and substage. The advantages of such a system would be that it would allow more reliable comparison of treatment results within and between institutions, and would provide more equivalent stratification groups for patients entering clinical trials of new therapies and those entering adjuvant therapy trials. A further advantage would be that because there would be a direct link between staging and prognostic estimate, such a system would be more readily able to be understood in an intuitive fashion.

The staging of malignant melanoma and the Florida Melanoma Trial

Lymphatic mapping and sentinel lymph node (SLN) biopsy have changed the standard of care for patients with malignant melanoma, by providing a less morbid procedure to obtain the nodal staging information that is critical for therapeutic decisions. Detailed examination of the SLN identifies patients who have an increased risk for recurrence and death. Patients whose melanoma is upstaged with very sensitive assays based on reverse transcriptase polymerase chain reaction technology are better targeted for clinical trials or surgical or adjuvant therapies. In the future, melanoma may be "ultrastaged" by examining the SLNs, peripheral blood, and bone marrow. This may improve identification of patients who are surgically cured of their disease and therefore can be spared the side effects of more radical surgery or the toxicities of adjuvant therapy. The lymphatic mapping procedure is the most accurate way to determine the tumor status of the regional lymph nodes.

Persistent evidence of circulating tumor cells detected by means of RT-PCR for CEA mRNA predicts early relapse: A prospective study in node-negative breast cancer

BACKGROUND

In 100 consecutive patients with node-negative breast cancer who underwent curative surgery, we prospectively tested whether detection of circulating tumor cells in peripheral blood by means of reverse transcription-polymerase chain reaction for carcinoembryonic antigen (CEA) messenger RNA (mRNA) could predict patient outcomes.

METHODS

We performed reverse transcription-polymerase chain reaction in blood samples taken before surgery and in repeat samples taken 2 to 3 weeks after surgery. Univariate and multivariate analyses of relapse-free survival were performed.

RESULTS

Patients with CEA mRNA in preoperative samples had poorer survival rates than those who had no detectable CEA mRNA. The worst survival rate was seen in those with CEA mRNA in both pre- and postoperative samples. Stepwise multivariate analysis selected CEA mRNA expression pattern (P=.001; relative risk=0.69) and histologic tumor grade (P=.002; relative risk=1.35) as independent prognostic factors for disease-free survival.

CONCLUSIONS

Molecular detection of CEA mRNA in both pre- and postoperative blood samples is an independent, negative prognostic factor in patients with node-negative breast cancer undergoing curative surgery.

Circulating tumor cells in patients with solid malignancy treated by high-intensity focused ultrasound

The theoretical possibility that exposure of a solid malignancy to high-intensity focused ultrasound (US), or HIFU, could lead to an increased rate of metastasis still remains. Using reverse transcriptase polymerase chain reaction (RT-PCR), the potential risk of hematogenous dissemination was assessed in HIFU-treated patients with solid malignancy. RT-PCR can demonstrate the presence or absence of specific RNA fragments. On the day before HIFU ablation, 5-mL peripheral blood samples were collected, and again 5 to 7 days after HIFU, from 26 enrolled patients (hepatocellular carcinoma, HCC: 10; osteosarcoma: 16). Total RNA was isolated and RT-PCR was performed to analyze the mRNA expression of (alpha-fetoprotein (AFP) and bone-specific alkaline phosphatase (BALP) genes. Positive AFP mRNA expression was preoperatively detected in 8 of 10 patients with HCC. In the postoperative specimens, positive expression was also detected in 8 of 10 patients. In 2 patients, circulating tumor cells were found preoperatively, but not postoperatively. Conversely, 2 patients with no circulating tumor cells preoperatively were found to have circulating tumor cells after HIFU. Of 16 osteosarcoma patients, 12 patients had circulating tumor cells and 4 had none. After HIFU treatment, 2 of the 12 patients had converted from presence to absence of circulating cells and the remaining 4 patients remained negative. It is concluded that patients undergoing complete HIFU ablation may demonstrate conversion from presence to absence of circulating tumor-specific marker mRNA, and that HIFU would not enhance the potential risk of metastasis in patients with malignant diseases.

Melanoma patient staging: histopathological versus molecular evaluation of the sentinel node

Lymphatic mapping and sentinel lymphadenectomy provide a minimally invasive means of directly determining the status of the regional lymph nodes in all patients who have a primary melanoma >1 mm thick but no clinical evidence of nodal involvement. Since the histological status of the sentinel node (SN) has been shown to be the most important prognostic factor in primary melanoma patients, the World Health Organization has recently recommended that sentinel lymphadenectomy should become the new standard of care for primary melanoma patients. This paper reviews the literature with regards to developments in and the current status of SN evaluation. Developments in the histopathological versus molecular detection of melanoma nodal metastases are reviewed, with specific emphasis on the strengths, limitations and clinical significance of these techniques. Molecular evaluation of the SN offers several advantages over standard histopathological analysis. These include an improved sensitivity, the cost-effective use of multiple markers for the improvement of detection rate and prognosis, as well as being less labour-intensive and costly. Moreover, molecular analysis has the potential to allow estimation of tumour burden. We review the potential causes of technical false-negative and false-positive reverse transcription-polymerase chain reaction (RT-PCR) results and how these could be eliminated by a systematic approach consisting of (i) careful and systematic assay design, which would include efficient tissue homogenization, choice of reagents and molecular markers, primer design and the use of one-stage versus two-stage PCR; (ii) careful optimization of the RT-PCR parameters (in particular the PCR cycle number) through the use of appropriate control tissues; and (iii) aiming for high assay reproducibility and lastly by applying the necessary positive and negative controls with each batch of samples. We also review the significant improvement in patient prognosis and management that has been made possible by the development of sentinel lymphadenectomy and histopathological evaluation of the SN, and compare the clinical (predictive) value of histopathological analysis with that of RT-PCR. Although RT-PCR is able to detect additional, clinically significant SN metastases that are missed by routine histopathology, its current limitation is that it overestimates the number of patients who have clinically significant melanoma metastases. Therefore, we suggest and discuss appropriate steps that need to be taken in order to minimize these false-positives and make this molecular tool more acceptable for routine clinical use.

Additional reverse transcription-polymerase chain reaction of peripheral slices is not superior to analysis of the central slice in sentinel lymph nodes from melanoma patients

BACKGROUND

The status of the sentinel lymph node (SLN) is an important prognostic factor in patients with cutaneous melanoma. Reverse transcription-polymerase chain reaction (RT-PCR) has been used as a sensitive means of detecting tumour cells in SLNs.

OBJECTIVES

To determine whether RT-PCR analysis of the SLN using both the central and the peripheral slices is more sensitive than molecular analysis of the central slice only.

METHODS

Eighty-three SLNs from 59 patients with primary cutaneous melanoma were identified by SLN mapping. All SLNs were bisected along their longitudinal axis to produce two equal halves. One half was used for histology and immunohistochemistry, and the other was analysed by RT-PCR for tyrosinase and MelanA. Parallel to the longitudinal axis, one central slice (approximately 2 mm in thickness) was cut manually. This central slice was used for our standard RT-PCR protocol. In the current study, up to eight additional peripheral slices (each approximately 2 mm in thickness) were cut parallel to the existing cut surface. These peripheral slices were analysed by additional RT-PCR.

RESULTS

Standard RT-PCR of the central slice yielded positive results in 34 of 59 patients (57%). Additional RT-PCR of peripheral slices demonstrated positive findings in six additional patients (10%) who were initially negative by standard RT-PCR of the central slice. In detail, seven of those 34 patients positive by standard RT-PCR of the central slice had positive histological findings. In each of these seven patients, RT-PCR was positive both in the central slice as well as in the peripheral slices. The remaining 27 patients with positive RT-PCR results of the central slice showed negative histological findings. Only nine (33%) of these 27 patients had a positive RT-PCR also in the peripheral slices. Finally, all 25 patients with negative RT-PCR results in the central slice showed negative histological findings. Six of these patients (24%) revealed positive RT-PCR results on the analysis of peripheral slices. However, three of these patients expressed only MelanA but not tyrosinase. Thirty lymph nodes from 24 nonmelanoma patients served as negative controls for RT-PCR. In three of these 24 patients (13%) expression of MelanA but not tyrosinase was detected by RT-PCR.

CONCLUSIONS

Molecular analysis of peripheral slices yielded six additional patients (10%) positive by RT-PCR who were initially negative by standard RT-PCR of the central slice. However, three of these six patients were found to express only MelanA but not tyrosinase. As MelanA expression was also found in 13% of control lymph nodes, positive MelanA expression alone in SLNs of melanoma patients requires cautious interpretation in order to avoid false-positive findings. Thus, additional molecular processing of peripheral slices did not significantly increase the number of patients with RT-PCR-positive SLNs.

Endogenous immune response to early- and intermediate-stage melanoma is correlated with outcomes and is independent of locoregional relapse and standard prognostic factors

BACKGROUND

Standard prognostic factors, including precise staging of the regional lymph nodes, cannot accurately determine which early-stage melanomas will metastasize. The immune response to a 90-kd tumor-associated antigen correlates with occult nodal disease and survival of patients receiving vaccine therapy for melanoma. We hypothesized that this response might have prognostic significance independent of standard prognostic features.

STUDY DESIGN

Patients with primary melanomas 1.01 to 2.00 mm and tumor-negative regional lymph nodes were identified. Group 1 comprised 50 patients who died of metastases within 7 years after complete surgical treatment; group 2 comprised 50 patients who were matched with group 1 for six standard prognostic features but who lived at least 10 years without recurrence. Postoperative sera were analyzed for an immune complex to TA90 and for immunoglobulin-G and immunoglobulin-M antibodies against TA90.

RESULTS

Median thickness of the primary melanoma was 1.40 +/- 0.31 mm and 1.42 +/- 0.32 mm in groups 1 and 2, respectively; median Clark's level of invasion was III in both groups, and 26 patients in each group had ulcerated primaries. Median TA90-IC level and rate of TA90-IC positivity (optical density greater than 0.410) were 0.557 +/- 0.43 and 82%, respectively, in group 1 and 0.305 +/- 0.15 and 18%, respectively, in group 2 (p < 0.001). The anti-TA90 IgM level was significantly elevated in 12% of group 1 (median titer 1:150) and 62% of group 2 (median titer 1:800) (p < 0.001). There was no significant difference in anti-TA90 IgG levels between the two groups.

CONCLUSIONS

A positive TA90-IC level and absence of an anti-TA90 IgM response correlate with distant metastasis when melanoma is low risk or intermediate risk by standard prognostic factors.

Detection of tyrosinase and tyrosinase-related protein 1 sequences from peripheral blood of melanoma patients using reverse transcription-polymerase chain reaction

BACKGROUND

malignant melanoma has one of the highest rates of metastasis. Unlike other solid cancers, no sensitive tumor markers or laboratory tests that can provide information of the risk of metastasis and predict the prognosis have yet been established.

OBJECTIVE

the study was done to establish a RT-PCR sensitive and specific enough to detect melanocyte-specific transcripts from peripheral blood cells.

METHODS

peripheral white blood cells were collected from 30 healthy donors and 43 melanoma patients. Melanocyte-specific tyrosinase (TYR) and tyrosinase-related protein 1 (TYRP1) were selected as targets of RT-PCR. The sensitivity of detection using SK-mel-23 melanoma cells and rates of false-positiveness using non-melanoma blood were compared between single-step PCR and nested PCR. Analysis of melanoma blood samples was carried out by the single-step PCR.

RESULTS

the nested RT-PCR amplified the TYR and TYRP1 sequences from 14 and 2 of the 30 healthy bloods, respectively. However, the single-step RT-PCR did not amplify TYR or TYRP1 sequences from any of the healthy controls. Our single-step RT-PCR detected 1.7 and 0.8 SK-mel-23 melanoma cells per ml blood for TYR and TYRP1, respectively. Overall, TYR mRNA was detected in 15 of the 43 melanoma patients (34.9%), and TYRP1 mRNA in 16 of the 43 (37.2%). The specificities of detection of TYR and TYRP1 were 83.3 and 88.9%, respectively.

CONCLUSION

our single-step RT-PCR for TYR and TYRP1 mRNAs is more specific than the previous nested RT-PCR for TYR and applicable to detect circulating melanoma cells.

Tyrosinase expression in the peripheral blood of stage III melanoma patients is associated with a poor prognosis: a clinical follow-up study of 110 patients

The aim of this study is to define the relationship between the tyrosinase expression in the peripheral blood and the clinical course of the disease in stage III disease-free melanoma patients after radical lymph node dissection. RT-PCR techniques were used to identify tyrosinase mRNA in 110 patients; a total of 542 blood samples were investigated. In all, 54 patients (49%) showed at least one positive result; 13 patients (11.8%) showed baseline positive results: six became negative thereafter, whereas seven showed follow-up positive results until disease progression occurred. One or more positive determinations were found during follow-up in 41 patients with negative baseline tyrosinase. No correlation was found between baseline results and the relapse rate or disease-free survival (DFS), whereas a significant correlation was found between positive tyrosinase results and disease recurrence during follow-up. In fact, 72.9% of positive patients relapsed, but only 19.3% of negative cases did so. The median interval between the positive results and the clinical demonstration of the relapse was 1.9 months (range 1-6.6). Disease-free survival multivariate analysis selected, as independent variables, Breslow thickness (P=0.05), lymph node involvement according to the AJCC classification (P=0.05) and tyrosinase expression (P=0.0001). In conclusion, RT-PCR tyrosinase mRNA expression is a reliable and reproducible marker associated with a high risk of melanoma progression and we encourage its clinical use in routine follow-up.

Detection of micrometastases in sentinel lymph nodes from melanoma patients

The technique of sentinel lymph node (SLN) dissection is a reliable predictor of metastatic disease in the lymphatic basin draining the primary melanoma. Reverse transcription-polymerase chain reaction (RT-PCR) is emerging as a highly sensitive technique to detect micrometastases in SLNs, but its specificity has been questioned. A prospective SLN study in melanoma patients was undertaken to compare in detail immunopathological versus molecular detection methods. Sentinel lymphadenectomy was performed on 57 patients, with a total of 71 SLNs analysed. SLNs were cut in slices, which were alternatively subjected to parallel multimarker analysis by microscopy (haematoxylin and eosin and immunohistochemistry for HMB-45, S100, tyrosinase and Melan-A/MART-1) and RT-PCR (for tyrosinase and Melan-A/MART-1). Metastases were detected by both methods in 23% of the SLNs (28% of the patients). The combined use of Melan-A/MART-1 and tyrosinase amplification increased the sensitivity of PCR detection of microscopically proven micrometastases. Of the 55 immunopathologically negative SLNs, 25 were found to be positive on RT-PCR. Notably, eight of these SLNs contained naevi, all of which were positive for tyrosinase and/or Melan-A/MART-1, as detected at both mRNA and protein level. The remaining 41% of the SLNs were negative on both immunohistochemistry and RT-PCR. Analysis of a series of adjacent non-SLNs by RT-PCR confirmed the concept of orderly progression of metastasis. Clinical follow-up showed disease recurrence in 12% of the RT-PCR-positive immunopathology-negative SLNs, indicating that even an extensive immunohistochemical analysis may underestimate the presence of micrometastases. However, molecular analyses, albeit more sensitive, need to be further improved in order to attain acceptable specificity before they can be applied diagnostically.

Tyrosinase RT-PCR as a Supplement to Histology for Detecting Melanoma and Nevus Cells in Paraffin Sections of Sentinel Lymph Nodes

The detection of tyrosinase mRNA in sentinel lymph nodes (SLNs) by reverse transcription polymerase chain reaction (RT-PCR) is a sensitive indicator for the presence of melanoma or nevus cells, but it does not enable a distinction between both. We have established an efficient method for extraction and reverse transcription of tyrosinase mRNA from paraffin sections that permits the close correlation of the RT-PCR results with (immuno)histologic findings in adjacent sections. One hundred fifty-three SLNs and 6 non-SLN specimens originating from 92 melanoma and 4 nonmelanoma patients were studied to test the reliability of this approach. The predictive value of positive RT-PCR results was 0.98 for the presence of melanoma or nevus cells; the corresponding negative predictive value was 0.83. Furthermore, the detection rate of tyrosinase mRNA significantly correlated with tumor burden. Among the 33 melanoma-positive SLNs without nevus cells, positive RT-PCR results were obtained in all specimens with extended peripheral (S2) or deeply invasive (S3) micrometastases but in only 46% of the cases with few localized melanoma cells in the subcapsular zone (S1). Routine (immuno)histologic evaluation alone had missed microclusters of melanoma cells in one SLN and small nevus cell aggregates in six other SLNs. They were detected only during microscopic reexamination caused by a positive RT-PCR result. We conclude that histology and immunohistochemistry remain the indispensable gold standard for the identification of melanoma and nevus cells in SLNs. Additional molecular analyses using adjacent paraffin sections may further improve the diagnostic accuracy by sensitizing and guiding the microscopist's attention.

The detection of tyrosinase mRNA in peripheral blood samples is unlikely to aid in the management of patients with localised malignant melanoma

A number of authors have reported the detection of tyrosinase mRNA in the peripheral blood of patients with malignant melanoma using the reverse transcription polymerase chain reaction (RT-PCR). The precise value of this assay as a prognostic tool, however, remains in doubt. This is particularly so with relation to localised disease, where relatively little data has been accumulated. In this study we analysed the peripheral blood of 50 consecutive patients with primary malignant melanoma referred to a plastic surgical centre with the facility of a pigmented lesion clinic. Samples were analysed from an additional 35 patients with advanced melanoma disease and 35 patients with benign pigmented cutaneous lesions. We were able to identify tyrosinase transcripts in the peripheral blood of only two of 50 patients with localised disease. Of those with more advanced disease, a positive finding was found in three with regional disease and four patients with metastatic spread. Stage of disease was found to correlate significantly with PCR status. No correlation was identified with other prognostic markers or with outcome over a three-year period. This data would support the conclusion that the detection of tyrosinase mRNA in peripheral blood is likely to be of little value as an aid in the management of patients with early malignant melanoma.

Measurement of thyroglobulin mRNA in peripheral blood as an adjunctive test for monitoring thyroid cancer

AIMS

Monitoring treated patients with thyroid cancer for recurrent or metastatic disease is currently based upon the serial measurement of circulating plasma thyroglobulin (Tg) concentrations. However, the clinical usefulness of Tg immunoassays is limited by poor sensitivity and interference from anti-Tg antibodies. This study investigated whether the detection of Tg mRNA in peripheral blood, using reverse transcriptase polymerase chain reaction (RT-PCR), is of value in the biochemical surveillance of patients with thyroid cancer.

METHODS

RNA was extracted from peripheral blood of five normal controls, six patients with abnormal thyroid function tests, and 28 patients who had undergone thyroidectomy for well differentiated thyroid cancer. From each, an 87 bp product from base pair 262 to 348 in the cDNA sequence of the thyroglobulin gene was amplified by RT-PCR.

RESULTS

Tg mRNA was detected in normal individuals and patients with thyroid cancer. In the group of patients studied, identification of metastatic thyroid tissue by radioiodine scanning correlated better with Tg mRNA assay results than with serum Tg concentrations (accuracy 84% v 75%). No interference from circulating Tg antibodies was apparent. In patients studied prospectively over a 12 month period, there was a significant correlation between detectable Tg mRNA in peripheral blood and the presence or absence of metastatic disease, as demonstrated by radioiodine scanning.

CONCLUSIONS

These results suggest that detection of Tg mRNA in blood is a more sensitive marker for metastatic thyroid disease than Tg immunoassay, and appears to be unaffected by the presence of circulating anti-Tg antibodies.

Biomarkers in melanoma: staging, prognosis and detection of early metastases

Currently, melanoma remains a surgical disease since early detection and excision of thin melanomas offers the best chance of a cure. Despite intensive clinical investigation, no effective systemic therapies exist for metastatic melanoma. Sentinel lymph node biopsy has greatly aided the staging and prognostic evaluation of primary cutaneous melanoma, however, approximately a third of patients diagnosed with metastatic melanomas present without prior regional lymph node involvement. Additional prognostic biomarkers exist which help determine the risk of advanced melanoma but the accuracy for each current marker is less than 100%. A greater understanding of the biology of melanomas and the development of new methods to identify patients with early (subclinical) metastatic disease may allow for selective and more effective therapy for patients at-risk for advanced disease. In this paper, current and novel potentially more accurate biomarkers for the staging and prognostic evaluation of melanoma patients, and for the detection of subclinical metastases are reviewed.

The role of molecular staging in malignant melanoma

AIMS

To review the role of tyrosinase RT-PCR in the detection of clinically occult metastatic disease, both within the regional lymph nodes and peripheral blood of patients with malignant melanoma. Secondly, to assess whether the detection of such minimal disease has clinical implications for patients with melanoma.

METHODS

A review of the literature was undertaken by searching the MEDLINE database for the period 1966-2002 without any language restrictions. Keywords included 'Molecular staging of melanoma', 'Reverse transcription polymerase chain reaction', 'Malignant melanoma' and 'Tyrosinase'.

CONCLUSIONS

Detection of tyrosinase RT-PCR positive cells within the peripheral blood correlates with the clinical stage of malignant melanoma, the primary tumour thickness and other known prognostic indicators. Positive tyrosinase RT-PCR is associated with a reduction of disease-free survival and overall survival. Current studies demonstrate a higher rate of recurrence in RT-PCR positive patients with clinical stage II and III disease. Implications of a positive result within the regional lymph nodes are less well defined. A significant correlation has been demonstrated between positive results and increasing primary melanoma thickness. However, a large number of false-positive results have been demonstrated, due to benign naevi and schwann cells, which may hamper any statistically significant conclusions being reached.

Detection of multiple melanoma-associated markers in melanoma cell lines by RT in situ PCR

New surgical oncology techniques, such as lymphatic mapping and sentinel node biopsy, require precise identification of the presence of even very small numbers of tumor cells. The gold standard for such analysis remains microscopic assessment of tissue sections, stained conventionally or by immunohistochemistry for appropriate tumor markers. This approach is limited by sampling constraints and requires a high degree of expertise from the microscopist. Recent studies have demonstrated a subgroup of patients whose sentinel nodes are negative on microscopy, but whose nodes yield an enhanced signal for melanoma markers when evaluated by RT-PCR. These enhanced signals reflect a mixture of signal sources, including small numbers of melanoma cells and cells other than melanoma cells that express the relevant markers(s). Because the preparative techniques for RT-PCR destroy the structural integrity of the tissues and disrupt individual cells, the exact cellular source of enhanced signal from a tissue cannot be demonstrated by conventional RT-PCR. RT in situ PCR, in which the RT-PCR technique is applied on a tissue section, does identify the cells that are the source of signal. We have attempted to optimize this interesting approach and have applied it to the detection of relevant melanoma markers in tissue culture lines.

Limitations of the immunocytochemical detection of isolated tumor cells in frozen samples of bone marrow obtained from melanoma patients

We report on a case of a 70-year-old woman with an ocular melanoma, which was diagnosed and treated 14 years ago. The patient was referred to the hospital with a suspected lymphoma. Cytological examination of bone marrow proved a marked infiltration with melanoma cells. Because detection of isolated tumor cells in the bone marrow of patients with various types of tumors was shown to be of prognostic significance and since current tumor-staging techniques are unable to detect single disseminated tumor cells or small aggregates of tumor cells, which might be the seed for subsequent metastatic relapse, we therefore evaluated the feasibility of immunocytochemical screening of bone marrow aspirates of 36 melanoma patients in different clinical stages using three monoclonal antibodies against melanoma-associated antigens in comparison with 43 non-melanoma control patients. Two of these antibodies (HMB45 and NKI-beteb) are directed against the melanoma antigen gp100/pmel17, whereas the third one (TA99) recognizes gp75/Tyrosinase-related protein 1 (TRP-1). None of the patients demonstrated a macroscopic bone marrow infiltration as was present in our patient with metastatic ocular melanoma. Seven (20.6%) of the 34 eligible melanoma patients presented with cells in the bone marrow positive for one or more of the above-mentioned melanosomal markers. Four of the positive patients were clinically free of tumors by the time of puncture, whereas the remaining 3 patients showed overt metastases in the subcutaneous fat (2 patients) and the brain (1 patient). On the other hand, 20 (66%) of the 29 patients with negative bone marrow findings also presented with clinical advanced disease with overt metastasis in the skin, lymph node, spleen, liver, lung, bone and brain. In conclusion, immunocytochemical screening of bone marrow samples is a feasible procedure that allows the detection of micrometastatic tumor cells in a subset of melanoma patients. Massive invasion of bone marrow with melanoma cells is a rare event even in far-advanced metastatic stages and no clear correlation between tumor load and bone marrow infiltration could be established.

Detection of circulating melanoma cells by a two-marker polymerase chain reaction assay in relation to therapy

Malignant melanoma is one of the most rapidly increasing cancer types, and patients with metastatic disease have a very poor prognosis. Detection of metastatic melanoma cells in circulation may aid the clinician in assessing tumor progression, metastatic potential, and response to therapy. Tyrosinase is a key enzyme in melanin biosynthesis. The gene is actively expressed in melanocytes and melanoma cells. Melan A is a differentiation antigen that is expressed in melanocytes. The presence of these molecules in blood is considered a marker for circulating melanoma cells. In this study, we analyzed the usefulness of this marker combination in evaluating the response to therapy in the blood of 30 patients with malignant melanoma. Circulating cells were detected by a reverse-transcriptase-polymerase-chain reaction. The tyrosinase expression was observed in 9 (30%) patients and Melan A in 19 (63.3%) patients before therapy. Following treatment, the tyrosinase mRNA was detected in only one patient, while Melan A transcripts were still present in 14 patients. We suggest that this molecular assay can identify circulating melanoma cells that express melanoma-associated antigens and may provide an early indication of therapy effectiveness.

Prognostic value of circulating melanoma cells detected by reverse transcriptase-polymerase chain reaction

PURPOSE

Factors that are predictive of prognosis in patients who are diagnosed with malignant melanoma (MM) are widely awaited. Detection of circulating melanoma cells (CMCs) by reverse transcriptase-polymerase chain reaction (RT-PCR) has recently been postulated as a possible negative prognostic factor. Two main questions were addressed: first, whether the presence of CMCs, defined as the patient being positive for any of the three markers, had a prognostic role; and second, what the predictive value of each individual marker was.

PATIENTS AND METHODS

A consecutive series of 200 melanoma patients observed between January 1997 and December 1997, with stage of disease ranging from I to IV, was analyzed by semiquantitative RT-PCR. Tyrosinase, p97, and MelanA/MART1 were used as markers to CMCs on baseline peripheral blood samples. Progression-free survival (PFS) was used as a unique end point and was described by the product limit method. Multivariable analysis was applied to verify whether the auspicated prognostic value of these markers was independent of the stage of disease, and a subgroup analysis was performed that excluded patients with stage IV disease.

RESULTS

Overall, 32% (64 of 200) of patients progressed, and a median PFS of 52 months in the whole series was observed. The presence of CMCs and the markers individually or combined was predictive of prognosis in the univariate analysis but did not provide additional prognostic information to the stage of disease in multivariable models. In the subgroup analysis of stage (ie, I-III subgroup), similar results were observed.

CONCLUSION

Detection of CMCs in peripheral blood samples at the time of MM diagnosis by semiquantitative RT-PCR does not add any significant predictive value to the stage of disease. Thus, this approach should not be used in clinical practice, and further studies are required to determine its usefulness.

Detection of micrometastatic cells in breast cancer by RT-pCR for the mammaglobin gene

The detection of circulating cancer cells in the bone marrow (BM) and peripheral blood (PB) of patients with solid tumors may be useful for disease staging. To this aim, we evaluated the expression of the mammaglobin gene by reverse transcriptase polymerase chain reaction (RT-PCR) in 60 patients with breast cancer. Moreover, several controls were examined to test the specificity of this marker. The positive cases included 23.6% of the patients with and 9% of those without metastasis. Only 4/60 negative controls analyzed were positive by PCR. Our results show high specificity and a good correlation with disease status.

Detection of melanoma seeding during surgical procedures--an RT-PCR based model

AIM

It has long been suggested that malignant cells may be shed into the blood stream during any given surgical procedure for cancer. A number of studies have now reported the detection of occult melanoma cells in peripheral blood using a reverse transcriptase polymerase chain reaction (RT-PCR) based assay. The principal aim of these studies has been to determine a prognostic value for the test and not to evaluate the influence of intervention upon results.

METHODS

In this pilot study we aimed to determine whether the assay could be used as a model to detect cells that are seeded during surgery. Peripheral blood samples were obtained pre- and post-operatively on twenty patients undergoing surgery for malignant melanoma - ten with primary disease and ten undergoing regional lymphadenectomy. A further ten patients undergoing surgery for non-melanoma conditions provided controls.

RESULTS

Using RT-PCR, it was possible to identify tyrosinase transcripts in the peripheral blood of one of ten patients undergoing excision of local disease and four of ten undergoing surgery for regional metastatic disease.

CONCLUSION

It was concluded that this technique does enable detection of a greater percentage of RT-PCR findings post-operatively. This in turn may provide a means for optimizing or comparing surgical techniques and provides a potential guide in the use of adjuvant therapies.

Specificity of tyrosinase and HMB45 PCR in the detection of melanoma metastases in sentinel lymph node biopsies

AIMS

Sentinel lymph node biopsy is an increasingly established procedure in the primary staging of high-risk melanoma patients. However, the laboratory evaluation of sentinel lymph node biopsies is a matter of controversy. The aim of this study was to determine the specificity of polymerase chain reaction (PCR) techniques for the evaluation of lymph nodes with regard to melanoma metastases in comparison with histology and immunohistology.

METHODS AND RESULTS

Sentinel lymph nodes (n = 41) from 29 melanoma patients and 29 lymph nodes from 27 patients without melanoma were analysed by histology (H&E) and immunohistology (Melan A, HMB45). cDNA of these lymph nodes was subjected to LightCycler PCR amplification using primers specific for tyrosinase and HMB45. Two melanoma sentinel lymph nodes contained naevus cells by histology and immunohistology and were therefore excluded from further evaluation. Eight (20.5%) of the remaining 39 melanoma sentinel lymph nodes were positive by histology and immunohistology and tyrosinase PCR, 15.4% (6/39) were positive only by tyrosinase PCR, 2.6% (1/39) were positive only by histology and immunohistology. HMB45 PCR revealed positive results in 7.7% (3/39) sentinel lymph nodes, which were also positive by tyrosinase PCR and histology and immunohistology. Of non-melanoma lymph nodes 13.8% (4/29) and 14.8% (4/27) of non-melanoma patients were positive by tyrosinase PCR but negative by histology and immunohistology and HMB45 PCR. Thus, tyrosinase PCR had a specificity of only 85.2%.

CONCLUSIONS

The specificity of tyrosinase PCR and the sensitivity of HMB45 PCR are too low to recommend these PCR examinations for the guidance of therapy, in particular complete regional lymph node dissection.

Quantitative RT-PCR assessment of melanoma cells in peripheral blood during immunotherapy for metastatic melanoma

Circulating malignant cells in peripheral blood are thought to be precursors and surrogate markers of distant metastases and hence markers of a poor clinical outcome. In this study, we used the detection of MART-1 and tyrosinase (TYR) mRNA with a quantitative reverse transcription-polymerase chain reaction (RT-PCR) assay to identify circulating melanoma cells. Blood samples were obtained from 35 patients with metastatic melanoma before, during and after treatment with interleukin-2, interferon-alpha and cisplatin. In addition, MART-1 and TYR protein was identified by immunohistochemistry in consecutive biopsies from 15 of the patients. Analysis of three daily blood samples for 3 days demonstrated that four out of 11 patients examined were negative for both markers on all occasions, and two patients were positive for both markers on all occasions but one. The remaining five patients showed sporadic low positive results for one or the other of the two markers. By comparing the immunohistochemistry results from consecutive biopsies with the RT-PCR results, we demonstrated that patients with MART-1 and TYR protein in their tumour cells had circulating MART-1 and TYR mRNA in 77% and 54% of the cases, respectively. During treatment, the majority of patients who were positive for MART-1 and TYR mRNA converted to being negative. However, these conversions did not significantly correlate with objective response. The presence of TYR mRNA in one of the first two samples showed a trend towards being an independent prognostic factor for poor survival.

Detection of circulating cells expressing chromogranin A gene transcripts in patients with lung neuroendocrine carcinoma

High grade lung neuroendocrine carcinomas, like small and large cell neuroendocrine carcinomas, pose therapeutic problems. Most initially respond to chemotherapeutic agents, but early relapses are frequent and are resistant to the presently available treatments. Our study reports for the first time the development and evaluation of a test for detecting the presence of circulating tumour cells by measuring chromogranin A gene transcripts with reverse transcriptase-polymerase chain reaction (RT-PCR) and Southern blotting. The test is specific and sensitive (detection of 10 cancer cells/ml blood), and only minimally invasive. Positivity is statistically correlated to high grade neuroendocrine carcinomas and to a poor prognosis with a 3-fold higher lethal risk. The test now needs to be assessed for its usefulness as a tool in the initial staging procedures and follow-up by comparison with the recent immunoradiometric assay (RIA) for detection of chromogranin A in the serum.

Tyrosinase mRNA in blood of patients with melanoma treated with adjuvant interferon

PURPOSE

To evaluate the clinical significance of the detection of circulating melanoma cells in patients treated with adjuvant interferon and to determine their potential value as a marker of interferon response.

PATIENTS AND METHODS

We prospectively analyzed 616 peripheral-blood samples from 120 melanoma patients with stage IIA (n = 33), IIB (n = 22), III (n = 50), or IV (surgically resected) (n = 15) disease receiving adjuvant interferon alfa-2b therapy. Tyrosinase mRNA was assayed by reverse transcriptase polymerase chain reaction (RT-PCR) as a marker of circulating melanoma cells before the start of interferon and every 2 to 3 months thereafter.

RESULTS

With a median follow-up time of 32.3 months (range, 7.1 to 77.5 months), 47 patients (39.8%) relapsed and 31 (26%) died. During adjuvant interferon treatment, 76 patients (64%) had undetected circulating melanoma cells and 44 patients (36%) had a positive RT-PCR result in at least one sample. Actuarial 5-year disease-free survival was 62% in patients with persistently negative RT-PCR during interferon treatment and 38% for patients with positive RT-PCR during interferon (P =.02). Actuarial 5-year overall survival was 75% and 50%, respectively (P =.03).

CONCLUSION

Patients with melanoma and tyrosinase mRNA detected in the blood during adjuvant interferon therapy had a worse prognosis compared with patients with undetected tyrosinase mRNA during treatment. Further investigation into the detection of circulating melanoma cells as a surrogate marker of response to adjuvant interferon therapy is warranted.

Detection of tumor circulating cells by cytokeratin-20 in the blood of patients with granulosa cell tumors

OBJECTIVE

Cytokeratins (CKs) are constituents of the intermediate filaments of epithelial cells which are expressed in various combinations, depending on the epithelial type and the degree of differentiation. Using the reverse transcriptase-polymerase chain reaction (RT-PCR) technique, we recently demonstrated that cytokeratin-20 (CK-20), the most recently discovered cytokeratin, is expressed in endometrial carcinoma tumors, in blood, and in lymph nodes with micrometastases of patients treated for endometrial carcinomas. However, CK-20 expression could not be demonstrated in the endometrium of patients with benign diseases, in peripheral blood, in lymph nodes of healthy subjects, or in normal blood cells. The aim of this study was to examine whether CK-20 expression in blood can be used as a biomarker for the detection of the dissemination of malignant cells in patients treated for granulosa cell tumors (GCTs).

METHODS

In this study, we used RT-PCR to determine the expression of CK-20 in the following groups: (i) blood of patients (n = 14) treated for GCTs, (ii) GCT samples (n = 4); (iii) lymph nodes (n = 2) of patients treated for GCTs; (iv) blood from subjects with benign sex-cord-stromal tumors (n = 2); (v) normal ovaries of two menstruating women (n = 4); (vi) tumor specimens of epithelial ovarian carcinomas (EOCs) (n = 14); and (vii) blood samples (n = 18) and lymph nodes (n = 11) of healthy women.

RESULTS

In Group I, CK-20 was positive in the blood in 86% (12/14) of the patients. In Group II, CK-20 was positive in 100% (4/4) of the GCT samples. In Group III, CK-20 was positive in 100% (2/2) of the lymph nodes examined. In Groups IV and V, CK-20 was negative in 100% (2/2) of the blood samples and in the normal ovarian specimens (4/4) that were examined. In Group VI, CK-20 was positive in 14% (2/14) of nonmucinous EOCs. In Group VII, CK-20 was negative in 100% (18/18) of blood and in (11/11) lymph node specimens (specificity 100%).

CONCLUSIONS

These results indicate that RT-PCR of CK-20, because of its high sensitivity and specificity, is a potential biomarker for detecting metastases in blood and in micrometastases in lymph nodes of patients treated for GCTs.

Application of differential display to identify genes for lung cancer detection in peripheral blood

A blood assay for detection of lung cancer biomarkers could significantly improve cancer patient prognosis and survival rates. Amplified fragment length polymorphism-differential display (AFLP-DD) was used to identify gene transcripts found in lung cancer tissue and the peripheral blood of lung cancer patients. The clones were evaluated for gene expression in lung cancer tissue, peripheral blood of lung cancer patients and healthy volunteers' blood. The isolated gene transcript clones were found to be from the syndecan 1 gene, collagen 1 gene and 2 novel genes. All 4 transcripts were expressed in normal lung tissue, 4 cultured primary lung cells and 6 lung cancer cell lines. RNA was isolated from peripheral blood samples of 69 lung cancer patients. Reverse transcriptase polymerase chain reaction (RT-PCR) was used to test for the presence of cytokeratin 19 and the 4 gene mRNA transcripts in blood RNA. The positive detection rate of at least 1 of the 5 transcripts was 79% for lung adenocarcinoma and 62% for squamous carcinoma. Using RT-PCR, at least 1 of the markers was found in 53% of stage I patients, 100% of stage II, 71% of stage III and 81% of stage IV lung cancer patients. Blood samples from 20 healthy volunteers were also tested, but only 1 of the 5 transcripts was found in 1 patient. These new molecular markers may aid early detection, staging and follow-up of lung cancer patients by RNA isolated from blood.

Preoperative evidence of circulating tumor cells by means of reverse transcriptase-polymerase chain reaction for carcinoembryonic antigen messenger RNA is an independent predictor of survival in non-small cell lung cancer: a prospective study

OBJECTIVE

We conducted a prospective study of 103 consecutive patients with non-small cell lung cancer who underwent a curative lobectomy to test whether circulating tumor cells detected in the peripheral blood by means of reverse transcriptase-polymerase chain reaction of carcinoembryonic antigen messenger RNA is a prognostic indicator independent of tumor stage in patients with non-small cell lung cancer.

METHODS

We assayed for carcinoembryonic antigen messenger RNA by means of reverse transcriptase-polymerase chain reaction in peripheral blood taken at the time of diagnosis before an operation and again 2 to 3 weeks after an operation from patients with non-small cell lung cancer who underwent a curative lobectomy between March 1996 and April 1998. We analyzed the prognostic value of carcinoembryonic antigen messenger RNA expression in the patients with non-small cell lung cancer in a univariate and multivariate manner.

RESULTS

Patients with carcinoembryonic antigen messenger RNA in the preoperative blood samples had a poor survival when compared with those without carcinoembryonic antigen messenger RNA. Of these patients, the worst survival was seen in those with carcinoembryonic antigen messenger RNA in the postoperative blood samples. The multivariate stepwise analysis selected the preoperative carcinoembryonic antigen messenger RNA expression (P =.0004; relative risk, 0.21) and the pathologic stage of disease (P =.0002; relative risk, 1.43) as the independent prognostic factors for survival.

CONCLUSIONS

The molecular detection of carcinoembryonic antigen messenger RNA in the preoperative peripheral blood is an independent prognostic factor in patients with non-small cell lung cancer who undergo a curative operation.

Magnetic bead RT-PCR: establishment of a new method for detecting circulating melanoma cells

This study was performed to detect circulating melanoma cells in peripheral blood using a novel method based on magnetic-activated cell separation (MACS) followed by a nested reverse transcriptase-polymerase chain reaction (RT-PCR) for tyrosinase and MART-1 mRNA. Samples to be tested were enriched for tumour cells either by isolating melanoma cells using two anti-melanoma antibodies (MART-1 and HMB-45) or by CD45 depletion of the non-melanoma cell fraction. The tumour cell-enriched fractions were subjected to mRNA isolation using oligo-deoxythymidylate (oligo-dT) magnetic beads followed by a nested RT-PCR. Sensitivity was assessed by spiking experiments and compared with a commonly used total RNA isolation system previously established in our department. Positive isolation of melanoma cells showed insufficient sensitivity, whereas negative isolation by depletion of leukocytes showed a detection limit of at least one melanoma cell per millilitre of whole blood. In further experiments, the depletion assay was applied to 25 peripheral blood samples of melanoma patients. The preliminary data obtained from the new method indicate a comparable detection rate to the established total RNA extraction method. However, not all the results were concordant. Therefore, future experiments need to be performed with a statistically greater number of patients.

Prognostic value of tyrosinase reverse-transcriptase polymerase chain reaction in metastatic melanoma

BACKGROUND

Circulating tumor cells can now be identified in subjects with metastatic melanoma by using the reverse-transcriptase polymerase chain reaction (RT-PCR) to detect the messenger RNA of tyrosinase, a key enzyme of melanogenesis.

AIM AND METHODS

The aim of this study was to determine whether the detection of positive tyrosinase cells in patients at metastatic stage was associated with a worse evolution. 32 patients were included with metastatic melanoma (AJCC IV).

RESULTS

66% had a positive tyrosinase RT-PCR and a shorter survival compared with patients with a negative RT-PCR, but this difference is not statistically significant. However, a positive test could appear indicative of rapid progression and poor prognosis.

CONCLUSION

The prognostic value of this method could be improved by combining it with PCR of other melanoma markers (Melan A, Mage 3) or assays of serum markers (S 100 protein or lactate dehydrogenase).