Microphthalmia transcription factor as a molecular marker for circulating tumor cell detection in blood of melanoma patients

PURPOSE

Microphthalmia transcription factor (Mitf), which is important in melanocyte development and melanoma growth, was assessed using real-time quantitative reverse transcription-PCR assay to investigate its expression as a marker for circulating melanoma cells in blood and determine the correlation with disease stage and survival in melanoma patients.

EXPERIMENTAL DESIGN

In optimization studies for Mitf, we tested 15 melanoma cell lines, 41 peripheral blood lymphocytes from healthy volunteers, and 21 metastatic melanoma tissues. Blood specimens were procured from 90 patients with stage I (n = 20), stage II (n = 20), stage III (n = 28), and stage IV (n = 22) melanoma. Blood specimens were also obtained at four bleed intervals from 58 patients enrolled in a prospective multicenter trial of biochemotherapy before and after surgical treatment of American Joint Committee on Cancer stage III melanoma.

RESULTS

Under the optimized conditions, Mitf was negative in healthy peripheral blood lymphocytes and positive in all melanoma cell lines and 18 (86%) melanoma tissues. In the 90 patients, the rate of Mitf detection was higher with increasing American Joint Committee on Cancer stage (P < 0.0001). In the 58 patients treated with biochemotherapy and surgery, Mitf detection decreased with treatment (P = 0.019). Mitf detection after treatment was associated with a significantly lower relapse-free (P < 0.0001) and overall (P = 0.001) survival and was a significant independent prognostic factor for relapse-free (risk ratio, 5.63; P = 0.0004) and overall (risk ratio, 5.36; P = 0.005) survival.

CONCLUSIONS

Mitf detection in blood can indicate subclinical metastatic disease and predict treatment outcome in melanoma patients.

Survivin expression by metastatic melanoma predicts poor disease outcome in patients receiving adjuvant polyvalent vaccine

Survivin and livin are members of the inhibitor of apoptosis protein (IAP) family. We hypothesized that elevated expression levels of these 2 IAP genes in resected advanced-stage metastatic melanoma lesions would be associated with poor disease outcome in patients receiving a polyvalent therapeutic cancer vaccine (Canvaxintrade mark). A quantitative real-time RT-PCR (qRT) assay for survivin and livin genes was used to assess mRNA expression in 63 metastatic melanomas obtained during cytoreductive surgery of American Joint Committee on Cancer (AJCC) stage IV melanoma. Nineteen of 63 metastatic melanoma patients received Canvaxin pre- and postoperatively, and 37 patients received only postoperative Canvaxin. Expression of survivin and livin protein was assessed by immunohistochemistry (IHC) and then correlated with mRNA. Survivin mRNA was detected in 62 of 63 (98%) melanoma specimens ranging from 0-5.96 x 10(4) mRNA copies of total RNA. Lower mRNA copy levels of survivin significantly correlated with improved overall survival among the 37 patients who received Canvaxin postoperatively but not preoperatively (log-rank test, p = 0.023). Among patients with low survivin mRNA copies, those who received postoperative Canvaxin did significantly better than patients who received pre- and postoperative Canvaxin (p = 0.003). Livin mRNA was detectable in 60 of 63 (95%) metastatic melanoma specimens but had no significant prognostic utility. These studies demonstrate that lower levels of survivin in recurrent metastatic melanomas are associated with significantly improved survival in patients receiving postoperative adjuvant immunotherapy. Overall, the study indicates survivin expression in metastatic melanomas can significantly influence disease outcome and patient responses to immunotherapy.

Multimarker quantitative real-time PCR detection of circulating melanoma cells in peripheral blood: relation to disease stage in melanoma patients

BACKGROUND

Detection of melanoma cells in circulation may be important in assessing tumor progression. The objective of this study was to develop a specific, reliable multimarker quantitative real-time reverse transcription-PCR (qRT) assay for detecting melanoma cells in patients' blood.

METHODS

We developed qRT assays for the mRNA of four melanoma-associated markers: MART-1, GalNAc-T, PAX-3, and MAGE-A3. In optimization studies, we tested 17 melanoma cell lines and 49 peripheral blood leukocyte (PBL) samples from volunteers. We performed RNA and melanoma cell dilution studies to assess the detection limits and imprecision of the assays. We measured the mRNAs in blood specimens from 94 melanoma patients [American Joint Committee on Cancer (AJCC) stage I, n = 20; II, n = 20; III, n = 32; IV, n = 22].

RESULTS

All markers were frequently detected in melanoma cell lines, whereas none of the markers was detected in PBLs from volunteers. The qRT assay could detect 1 melanoma cell in 10(7) PBLs in the melanoma cell-dilution studies. Markers were detected in 15%, 30%, 75%, and 86% of melanoma patients with AJCC stage I, II, III, and IV disease, respectively. The number of positive markers and AJCC stage were significantly correlated (Spearman correlation coefficient = 0.58; P < 0.0001).

CONCLUSIONS

Multimarker qRT can detect circulating melanoma cells in blood. Measurement of the studied molecular markers in blood may be useful in detection of metastasis and monitoring treatment response of melanoma patients.

Detection of occult metastatic breast cancer cells in blood by a multimolecular marker assay: correlation with clinical stage of disease

Currently, molecular markers offer the unique opportunity to identify occult metastasis in early stage cancer patients not otherwise detected with conventional staging techniques. To date, well-characterized molecular tumor markers to detect occult breast cancer cells in blood are limited. Because breast tumors are heterogeneous in tumor marker expression, we developed a "multimarker" reverse transcription-PCR assay combined with the highly sensitive electrochemiluminescence automated detection system. Breast cancer cell lines (n = 7), primary breast tumors (n = 25), and blood from normal donors (n = 40) and breast cancer patients [n = 65; American Joint Committee on Cancer (AJCC) stages I-IV] were assessed for four mRNA tumor markers: beta-human chorionic gonadotropin (beta-hCG), oncogene receptor (c-Met), beta 1-->4-N-acetylgalactosaminyl-transferase, and a tumor-associated antigen (MAGE-A3). None of the tumor markers were expressed in any normal donor bloods. Breast cancer cell lines and primary breast tumors expressed beta-hCG, c-Met, beta 1-->4-N-acetylgalactosaminyl-transferase, and MAGE-A3 mRNA. Of the 65 breast cancer patient blood samples assessed, 2, 3, 15, 49, and 31% expressed 4, 3, 2, 1, and 0 of the mRNA tumor markers, respectively. At least two markers were expressed in 20% of the blood specimens. The addition of a combination of markers enhanced detection of systemic metastasis by 32%. In patient blood samples, the MAGE-A3 marker correlated significantly with tumor size (P = 0.0004) and AJCC stage (P = 0.007). The combination of beta-hCG and MAGE-A3 mRNA markers correlated significantly with tumor size (P = 0.04), and the marker combination c-Met and MAGE-A3 showed a significant correlation with tumor size (P = 0.005) as well as AJCC stage (P = 0.018). A multimarker reverse transcription-PCR assay that correlates with known clinicopathological prognostic parameters may have potential clinical utility by monitoring tumor progression with a blood test.

Detection of MAGE-A3 in breast cancer patients' sentinel lymph nodes

The detection of occult metastatic breast cancer cells by RT-PCR is limited by the poor specificity of most tumour mRNA markers. MAGE-A3 is a highly specific tumour mRNA marker that is not expressed in non-cancer cells. This study assesses MAGE-A3 mRNA as a molecular marker for the detection of tumour cells in the sentinel lymph nodes (SLN) of breast cancer patients. Serial frozen sections of SLN (n = 121) were obtained from 77 AJCC (American Joint Committee on Cancer) Stage I-IIIA breast cancer patients. MAGE-A3 mRNA analysis of SLN was performed by RT-PCR and Southern blot analysis. Tumour cells were detected in 48 of 121 (40%) SLN from 77 patients by H&E or IHC staining, and 35 of 77 (45%) patients, overall, had histopathologically (H&E and/or IHC) positive SLN. Among histopathologically negative SLN, 28 of 73 (38%) SLN were MAGE-A3 mRNA positive by RT-PCR. Overall, 41 of 77 (53%) patients and 50 of 121 (41%) SLN were positive for MAGE-A3. MAGE-A3 mRNA expression in the SLN occurred more frequently with infiltrating lobular carcinoma (P < 0.001) than with infiltrating ductal carcinoma, adding further evidence of possible phenotypic differences between these 2 subtypes of breast cancer. Due to its high specificity, MAGE-A3 mRNA is a potentially useful marker for detecting breast cancer cells in the SLN. One half of breast tumours expressed MAGE-A3 mRNA, which has important potential implications for antigen-specific targeted immunotherapy.

Microsatellite alterations detected in the serum of early stage breast cancer patients

Breast cancer is the most common malignancy affecting women. Advances in screening have resulted in an increasing trend towards detecting earlier stage tumors associated with a longer disease-free survival. Because of this prolonged latency period, it is critical to identify patients early in their disease course who are at increased risk for recurrence, whereby treatment decisions may be altered accordingly based on more precise information. Molecular markers that demonstrate prognostic importance as well as utility for assessing subclinical disease progression offer one such approach. Specifically, circulating microsatellite alterations that reflect those genetic events occurring in tumors and that can be serially assessed through a minimally invasive procedure are a logistically practical method. In this study, serum was collected preoperatively from 56 patients with early stage breast cancer (AJCC stages I/II) and assessed for loss of heterozygosity (LOH) using 8 microsatellite markers. Twelve (21%) of 56 patients demonstrated LOH in their serum for at least one marker. Histopathologic correlation revealed an association between the presence of circulating LOH in serum and those tumors with increased proliferation indices as characterized by an increased diploid index, elevated MIB-1 fraction, and abnormal ploidy. These findings demonstrate the presence of circulating microsatellite alterations in the serum from patients with early stage breast cancer. The association of known poor prognostic features found in tumors with increased nuclear activity not only suggests a possible etiology for their presence, but also offers a potential blood-based surrogate marker for this disease that may demonstrate clinical utility in long-term follow-up studies.

Molecular detection of metastatic melanoma cells in cerebrospinal fluid in melanoma patients

Melanoma frequently metastasizes to the central nervous system (CNS). The diagnosis of CNS metastases typically is made following the onset of clinical symptoms. Thus, more sensitive diagnostic approaches are needed to identify subclinical CNS metastases. Currently, standard cytologic analysis of the cerebrospinal fluid (CSF) is limited by its poor sensitivity. A more sensitive assay was therefore developed using multiple reverse transcriptase-polymerase chain reaction (RT-PCR) markers. CSF was collected and assessed by RT-PCR for three known melanoma-associated markers (MAGE-3, MART-1, and tyrosinase) to detect occult metastatic melanoma cells in the CSF of 37 American Joint Committee on Cancer (AJCC) stage IV melanoma patients. Cytologic analysis of CSF was performed on all patients, and immunohistochemistry (IHC) analysis was performed on 33 CSF samples using anti-S100 and anti-HMB-45 antibodies. Only one patient (3%) had tumor-positive CSF cytology and IHC upon entry into the study, whereas 12 patients (32%) were positive for at least one RT-PCR marker. The correlation between CSF RT-PCR positivity of MART-1 and/or MAGE-3 and the development of CNS metastases at 3 mo was significant (p = 0.04). Fifteen of 37 patients (41%) had either positive MRI and/or positive RT-PCR results. Multimarker RT-PCR is more informative and sensitive than cytology/IHC in assessing the CSF of melanoma patients.

Prognostic significance of circulating microsatellite markers in the plasma of melanoma patients

PURPOSE

Multiple genetic alterations including loss of heterozygosity (LOH) occur commonly in melanoma tumors. We demonstrated previously free-circulating DNA microsatellites with LOH in the blood of melanoma patients. These LOH markers in plasma may be useful as surrogates for subclinical disease progression. The purpose of this study was to determine whether the presence of circulating tumor microsatellite markers in the preoperative blood from patients with melanoma has prognostic utility.

EXPERIMENTAL DESIGN

Plasma was analyzed for the presence of LOH at six chromosome regions, which are common for allelic loss in melanoma tumors, in 57 patients undergoing surgical resection of all of the clinically apparent disease.

RESULTS

LOH was detected in 32 of 57 patients (56%). Both LOH incidence and frequency correlated with advancing American Joint Committee on Cancer stage. In patients with American Joint Committee on Cancer stage III, the presence of LOH as an independent variable in preoperative plasma was significantly associated (P = 0.05) with an increased risk of death. Furthermore, LOH at microsatellite marker D1S228 in the plasma of patients with advanced disease correlated significantly (P = 0.0009) with a poorer survival after surgical resection. LOH commonly found in melanoma tumors can be successfully identified in the plasma of a patient, providing a potentially less invasive route for following genetic changes that serve as molecular surrogates for assessing subclinical disease progression.

CONCLUSIONS

This study provides evidence that blood testing for circulating tumor genetic markers may provide valuable prognostic information and guide future therapy.

Ganglioside GM2/GD2 synthetase mRNA is a marker for detection of infrequent neuroblastoma cells in bone marrow

GalNAcbeta1-4(NeuAcalpha2-3)Galbeta1-4Glcbeta1-Cer (GM2)/GalNAcbeta1-4(NeuAcalpha2-8NeuAcalpha2-3)Galbeta1-4Glcbeta1-1Cer (GD2) synthetase [beta-1,4-N-acetyl-galactosaminyl transferase (GalNAc-T)] mRNA, which encodes a key glycosyltransferase for ganglioside GD2 synthesis, was assessed as a molecular marker for detecting metastatic neuroblastoma cells in bone marrow (BM). GalNAc-T mRNA expression by neuroblastoma cell lines (n = 15), primary untreated neuroblastoma tumors (n = 29), morphologically normal BM (n = 22), peripheral blood stem cells (n = 10) from patients with cancers other than neuroblastoma, and blood mononuclear cells from normal donors (n = 17) was assessed by using reverse transcriptase-polymerase chain reaction (RT-PCR) and electrochemiluminescence detection assay (RT-PCR/ECL). BM harvested from 15 neuroblastoma patients was tested before and after ex vivo immunomagnetic bead purging, and results were compared to immunocytological analysis of the same specimens. All neuroblastoma cell lines (mean, 653 x 10(3) ECL units) and primary tumors (mean, 683 x 10(3) ECL units) were positive for significant expression of GalNAc-T mRNA compared to normal blood and BM cells. The RT-PCR/ECL assay could detect GalNAc-T mRNA in 100 pg of total RNA, and in a mixture of one neuroblastoma cell among 10(7) normal BM or blood cells. Eight of 15 autologous BM cells harvested from patients with neuroblastoma had tumor cells detectable by immunocytology, and all 15 were positive for GalNAc-T mRNA. After ex vivo purging, none of the BM cells was immunocytology-positive, but six remained positive by the RT-PCR/ECL assay. GalNAc-T mRNA provides a specific and sensitive molecular marker for RT-PCR/ECL detection of infrequent neuroblastoma cells in BM.

Tumor-reactive T helper lymphocytes recognize a promiscuous MAGE-A3 epitope presented by various major histocompatibility complex class II alleles

The development of effective T cell-based immunotherapy for cancer requires the identification of antigens capable of inducing both CTL and T helper immune responses. Although CTLs will participate in the antitumor response mainly by exerting their lytic activity on the tumor cells, helper T lymphocytes will be critical for the induction and maintenance of the CTLs. Thus, effective subunit therapeutic vaccines should include both CTL and T helper epitopes from antigens expressed on the tumor cells. The product of the MAGE-A3 gene is an attractive candidate for tumor immunotherapy because it is expressed in the majority of melanomas and in a great proportion of other solid tumors. Although numerous CTL epitopes for the MAGE-A3 antigen have been reported, only a few have been described for helper T cells. Here we show that a synthetic peptide derived from the MAGE-A3 sequence (MAGE-A3(146-160)) was effective in inducing in vitro T helper responses in the context of HLA-DR4 and HLA-DR7 alleles. Most significantly, the peptide-reactive helper T lymphocytes were capable of recognizing various forms of MAGE-A3 antigen (tumor cell lysates, dead/apoptotic tumor cells, or recombinant MAGE-A3 protein), indicating that the T-cell epitope represented by peptide MAGE-A3(146-160) is naturally processed by antigen-presenting cells. These studies are relevant for the design of multi-epitope vaccines for treating MAGE-A3-expressing tumors through the simultaneous stimulation of CTL and T helper lymphocytes.

Molecular clonality of in-transit melanoma metastasis

In-transit melanoma is characterized by an aggressive pattern of recurrence that is associated with a poorer prognosis. Because in-transit melanoma is considered to result from the intralymphatic trapping of melanoma cells between the primary tumor and regional lymph nodes, it provides an excellent model to assess genetic events associated with early metastasis. The hypothesis of this study was to determine whether in-transit metastases are clonal in origin and therefore, may have specific genetic alterations uniquely associated with this disease and the development of early metastasis. This was assessed using loss of heterozygosity (LOH) analysis for specific DNA microsatellite loci. Seventy-nine paraffin-embedded in-transit melanoma lesions from 25 patients (range, 2 to 9 lesions per patient; average, 3.4 lesions per patient) were assessed for LOH using eight microsatellite DNA markers on six chromosomes. In 19 of 25 patients (76%) LOH was demonstrated for at least one marker. The most frequent microsatellite marker demonstrating LOH was D9S157 (56%). Using LOH microsatellite markers to assess intertumor heterogeneity, six of 79 tumors (7.6%) demonstrated different profiles when compared to other lesions from the same patient. In-transit metastases from those patients demonstrating intertumor heterogeneity were further assessed using laser capture microdissection and DNA analysis, and revealed no significant intratumor heterogeneity. In conclusion, LOH was frequently observed in in-transit melanoma metastasis. Based on LOH analysis, in-transit metastases are clonal in origin. The establishment of clinically successful in-transit melanoma metastasis requires specific genetic events that seem to be unique and homogeneous for each patient.

Molecular strategy for detecting metastatic cancers with use of multiple tumor-specific MAGE-A genes

BACKGROUND

The human melanoma-associated antigen family A (MAGE-A) has high specificity and expression in various malignancies, but individual family members are expressed at low frequency in any one particular type of cancer. We therefore developed a method to detect mRNAs from multiple MAGE-A genes in a single reaction.

METHODS

Universal MAGE-A (uMAGE-A) primers and probe were designed to reverse-transcribe, amplify, and detect by electrochemiluminescence (ECL) MAGE-A mRNAs on the Origen Analyzer. The assay was performed on total RNA of melanoma (n = 9 cell lines and 24 tumors), breast cancer (n = 7 and 26), and colorectal cancer (CRC; n = 5 and 12). We also evaluated blood from melanoma (n = 50), breast cancer (n = 16), and CRC (n = 21) patients.

RESULTS

The uMAGE-A mRNA was detectable in 0.01-1 ng of cell line RNA. The identity of the uMAGE-A cDNA products was confirmed by sequencing and polyacrylamide gel electrophoresis. The uMAGE-A assay increased detection of melanoma, breast cancer, and CRC tumor by 13%, 31%, and 25%, respectively, compared with a MAGE-A1 assay, and by 17%, 19%, and 25%, respectively, compared with a MAGE-A3 assay. The uMAGE-A assay detected circulating tumor cells in the blood of melanoma (24%), breast cancer (25%), and CRC (29%) patients.

CONCLUSIONS

The uMAGE-A reverse transcription-PCR/ECL assay provides a practical and sensitive approach for detection of various metastatic cancers in tissues and blood.

Molecular staging of early colon cancer on the basis of sentinel node analysis: a multicenter phase II trial

PURPOSE

Approximately 30% of patients with American Joint Committee on Cancer stage I or II colorectal cancer (CRC) develop systemic disease. We hypothesized that multimarker reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of sentinel lymph nodes (SNs) draining a primary CRC could detect micrometastases not detected by conventional histopathologic analysis.

PATIENTS AND METHODS

In a multi-institutional study, 40 patients with primary CRC underwent dye-directed lymphatic mapping at the time of colon resection. Each dye-stained SN was tagged, and the tumor and regional nodes were resected en bloc. All lymph nodes were examined by conventional hematoxylin and eosin (HE) staining. In addition, each SN was cut into multiple sections for cytokeratin immunohistochemical (CK-IHC) staining and for RT-PCR and electrochemiluminescent detection of three markers: beta-chain human chorionic gonadotropin, hepatocyte growth factor receptor, and universal melanoma-associated antigen. Whenever possible, RT-PCR assay was also performed on primary tumor tissue. The detection sensitivity of individual markers was 10(-3) to 10(-4) microg of RNA and one to five tumor cells in 10(7) lymphocytes of healthy donors.

RESULTS

One to three SNs were identified in each patient. An average of 15 nodes were removed from each CRC specimen. No nonsentinel (untagged) node contained evidence of tumor if all tagged (sentinel) nodes in the same specimen were histopathology tumor-negative. HE staining of SNs identified tumor in 10 patients (25%), and CK-IHC of SNs identified occult micrometastases in four patients (10%) whose SNs were negative by HE. Of the remaining 26 patients with no evidence of SN involvement by HE or CK-IHC, 12 (46%) had positive RT-PCR results. The number of markers expressed in each SN correlated (P <.04) with the T stage of the primary tumor. There was 79% concordance in marker expression for the respective pairs (n = 38) of primary tumor and histopathologically positive SNs, and 86% (12 of 14) concordance between RT-PCR positive and histopathologically positive SNs.

CONCLUSION

Identification and focused examination of the SN is a novel method of staging CRC. CK-IHC and RT-PCR identified occult micrometastases in 53% of patients whose SNs were negative by conventional staging techniques. These ultrasensitive assays of the SN can identify patients who may be at high risk for recurrence of CRC and therefore are more likely to benefit from systemic adjuvant therapy.

The clinical utility of multimarker RT-PCR in the detection of occult metastasis in patients with melanoma

Cutaneous melanoma is characterized by a high propensity for metastasis. Currently, surgical intervention remains the mainstay of therapy. This approach has proven most beneficial when the diagnosis is of early stage primary lesions. Likewise, patients undergoing resection for a solitary site of metastasis have shown a survival advantage. Identification of metastatic disease depends predominantly on radiographic techniques requiring the presence of significant tumor burdens for successful imaging. However, at that time, the role of surgery and/or biochemotherapy may be of limited value. Techniques to identify minimal disease states may permit more accurate assessment of prognosis. The detection of occult tumor cells by RT-PCR in the blood, lymph nodes, and bone marrow of melanoma patients provides one such approach to monitor tumor progression. Single-marker RT-PCR has been used as one such approach but is noted to have limitations in sensitivity and specificity based on the heterogeneity of tumor marker expression among tumors as well as within an individual tumor lesion or among multiple lesions in individual patients. We employed a multimarker reverse transcriptase polymerase chain reaction assay that demonstrates improved sensitivity over a single-marker approach. Currently, the consequences of detecting systemic subclinical metastasis remain unknown pending longer-term follow-up. The detection of occult melanoma cells using molecular techniques in conjunction with known clinicopathologic prognostic factors may provided a novel and efficient approach in monitoring tumor progression and further identify high-risk patients diagnosed early in the disease course.

Functional interleukin-4 receptor and interleukin-2 receptor common gamma chain in human gastric carcinoma: a possible mechanism for cytokine-based therapy

Interleukin (IL)-2 and IL-4 play a critical role in the regulation of the immune response. Yet both of the receptors for these cytokines have been found on nonhematopoietic cells, including human gastric carcinoma cell lines and tissue specimens. IL-4 causes G1 phase cell cycle arrest of gastric carcinoma; the effect directly correlates with the expression of IL-4 receptor (IL-4R) and is seen within 48 hours after treatment. Cells lacking IL-4R are unaffected by IL-4. We examined signal transduction pathways employed by IL-4 that may account for cell cycle arrest of an established human gastric carcinoma cell line, CRL 1739. Western blot analysis was performed on CRL 1739 cultured in the presence of IL-4 (500 U/ml). Cells were lysed, protein extracted, and electroblotted; blots were then probed with murine mono-clonal antibodies to specific intracellular proteins. Western blotting of CRL 1739 with antiphosphotyrosine antibody (4G10) demonstrated multiple (140 kDa and 65 kDa) phosphoproteins seen only in IL-4-treated CRL 1739. Immunoprecipitation and blotting of CRL 1739 with specific secondary antibodies demonstrated that the 140 kDa phosphoprotein was IL-4R", the 65kDa phosphoprotein was IL-2Rgc, the 130 kDa phosphoprotein was Janus kinase (JAK1), and the 116 kDa phosphoprotein was JAK3. Reverse transcription-polymerase chain reaction with specific primers demonstrated that multiple human gastric tumor specimens expressed IL-4R" and IL-2Rgc but did not express the leukocyte marker CD45. These results suggest that human gastric carcinomas may express functional cytokine receptors, including the IL-2Rgc commonly found in association with the lymphocyte IL-2R. These receptors may represent novel targets for directing cytokine-based therapy.

Microsatellite analysis of melanoma lesions using (CA)13 oligonucleotides as an internal probe

The accurate assessment of microsatellite loci on specific chromosome regions for loss of heterozygosity (LOH) is important to identify potential tumor suppressor gene locations and recently correlations to clinicopathology of tumors. Analysis of microsatellite markers usually requires performing polymerase chain reaction (PCR) with labeled primers. This often leads to spurious PCR products that make interpretations of specific PCR bands difficult. Assessment of LOH by radiolabeled PCR is not always easy to interperet when there are multiple bands present, multiple markers and specimens are being assessed, and in multiplex LOH PCR. We describe an approach to accurately verify PCR-based LOH in which labeled PCR primers are not needed to detect allele expression. Specificity is determined by using a digoxigenin-labeled oligonucleotide (CA)13 as an internal specific probe for hybridization. Because the majority of di-nucleotide microsatellite markers contain the sequence of (CA)n or (GT)n repeats, this (CA)n probe is highly versatile. Forty cutaneous melanoma biopsies from advanced stage patients were assessed using the oligonucleotide probe at five chromosome regions (1q, 6q, 9p, 10q, 11q). The LOH frequency in informative cases varied from 33% to 47% in which chromosome 6q was the highest followed closely by 11q. We observed a higher frequency of LOH in the 6q (47%) and 11q (41%) compared to previously reported studies using the probe technique. This new approach was also demonstrated to be efficient in multiplex-PCR to detect LOH in melanomas. Using the probe hybridization approach it was demonstrated that in advanced cutaneous melanomas LOH are quite frequently expressed on 5 different chromosome regions.

Induction of melanoma-associated antigen systemic immunity upon intratumoral delivery of interferon-gamma retroviral vector in melanoma patients

A total of 17 patients with metastatic melanoma were treated with intratumoral interferon-gamma (IFN-gamma) retroviral vector in a phase I clinical trial. A cycle of treatment consisted of five daily injections every 2 weeks. Patients were divided into two treatment arms that involved a single course (one cycle) of treatment (group I; n = 9) and multiple cycles (six cycles) of treatment (group II; n = 8). Patients received intratumoral injections of IFN-gamma (10(7) plaque-forming units/mL administered at 0.3, 0.5, and 1.0 mL per cohort of patients). All patients receiving multiple injections either maintained stable disease (n = 5) or achieved a partial or complete response (n = 3) of the injected lesion, whereas in patients receiving a single cycle of treatment, only one of nine patients had a response. Patients were assessed for immunoglobulin G antibody (Ab) responses to the melanoma-associated antigens (MAA) tyrosinase, gp100, TRP-2, and MAGE-A1 by affinity enzyme-linked immunosorbent assay. Anti-MAGE-A1 and tyrosinase Ab were significantly elevated from baseline (day 0) to week 16 during treatment (P = .005; P = .002, respectively) in patients who received multiple injections. Patients undergoing treatment who had a clinical response (stable disease or better) also had significantly more elevated Ab responses to a greater number of MAA (P = .0004). The induction of systemic Ab responses to multiple MAA also correlated with systemic clinical responses. These studies suggest that multiple anti-MAA Ab responses are associated with clinical responses to IFN-gamma retroviral treatment and may be used as surrogate response markers.

Molecular markers in blood as surrogate prognostic indicators of melanoma recurrence

Improvement is needed in the ability to evaluate the prognosis of melanoma patients who are clinically disease-free but likely to develop recurrent metastatic disease. The detection of circulating melanoma cells in blood is a potential surrogate marker of subclinical residual disease. We assessed the prognostic clinical utility of a multimarker melanoma reverse transcriptase-PCR (RT-PCR) assay using blood of 46 patients who were clinically disease-free. All patients were followed up for more than 4 years for disease recurrence. There was a significant correlation between number of RT-PCR markers present in blood and American Joint Committee on Cancer stage (P = 0.009). The number of RT-PCR markers detected in blood was an independent prediction factor of disease recurrence in a Cox proportional hazard model (P = 0.02). A risk factor model using American Joint Committee on Cancer stage and number of positive RT-PCR markers significantly predicted disease recurrence in 2, 3, and 4 years of follow-up. These studies demonstrate that molecular detection of circulating melanoma cells may be of significant prognostic value in determining early disease recurrence and may be useful for stratifying patients for adjuvant therapy.

Molecular detection of metastatic pancreatic carcinoma cells using a multimarker reverse transcriptase-polymerase chain reaction assay

BACKGROUND

The diagnosis of pancreatic carcinoma is often associated with a poor prognosis, because most patients already have advanced disease. A highly sensitive assay to detect the progression of pancreatic carcinoma would be of significant clinical utility. The authors developed multiple tumor mRNA markers for reverse transcriptase-polymerase chain reaction (RT-PCR) to detect metastatic tumor cells in the blood and tissue of patients with American Joint Committee on Cancer (AJCC) Stage II/III or IV pancreatic carcinoma.

METHODS

An RT-PCR plus Southern blot assay was used to detect mRNA of tumor markers in blood and tissues. mRNA expression of the tumor progression markers MET (hepatocyte growth factor receptor gene c-met), GalNAc-T (beta1,4- N-acetyl-galactosaminyl-transferase), and beta-hCG (beta-human chorionic gonadotropin) was evaluated in 9 pancreatic carcinoma cell lines, 13 tumor biopsy specimens, 5 nonmalignant pancreatic tissue specimens, and blood from 33 pancreatic carcinoma patients and 32 healthy donors.

RESULTS

The detection limit of the assay was 1 rhog, 10 rhog, and 10 rhog for MET, GalNAc-T, and beta-hCG mRNA expression, respectively. The pancreatic carcinoma cell lines expressed all three mRNA markers. Of blood specimens from 17 patients with AJCC Stage IV pancreatic carcinoma, 82%, 65%, and 76% were MET, GalNAc-T, and beta-hCG mRNA positive, respectively. Of blood specimens from 16 patients with AJCC Stage II/III disease, 88% were positive for at least 1 mRNA marker.

CONCLUSIONS

A multiple molecular marker assay was developed to detect cancer cells in blood and tissue from patients with different stages of pancreatic carcinoma. The detection of cancer cells in the blood may be used as a marker of pancreatic tumor progression and may be useful in monitoring response to therapy.

PTEN / MMAC1 mutation and frequent loss of heterozygosity identified in chromosome 10q in a subset of hepatocellular carcinomas

Frequent allelic losses on chromosome 10q have been reported in several types of cancers, suggesting the presence of a putative tumor suppressor gene(s) on the chromosomal arm. We examined loss of heterozygosity (LOH) on chromosome 10q in 37 hepatocellular carcinomas (HCC) using eleven dinucleotide microsatellite markers, spanning the entire chromosome arm of 10q. Twelve (32%) out of 37 informative cases showed allelic losses of at least one locus on 10q and eight tumors showed a partial deletion of 10q. Analysis of deletion mapping of these eight cases identified two commonly deleted regions within the distal part of 10q (10q24-q26), a 20-cM interval flanked by D10S597 and D10S216 and a 24-cM interval flanked by D10S216 and D10S590. Moreover, we detected a somatic missense mutation (Met --> Val) of a candidate tumor suppressor gene PTEN / MMAC1, located at 10q23.3, in one HCC with LOH of 10q. Our findings indicated the presence of putative tumor suppressor gene(s) in the distal region of 10q that might be involved in the development and progression of HCC. Inactivation of PTEN / MMAC1 gene located outside the commonly deleted region of 10q might also play an important role in a subset of HCCs.

Molecular detection of metastatic pancreatic carcinoma cells using a multimarker reverse transcriptase-polymerase chain reaction assay

BACKGROUND

The diagnosis of pancreatic carcinoma is often associated with a poor prognosis, because most patients already have advanced disease. A highly sensitive assay to detect the progression of pancreatic carcinoma would be of significant clinical utility. The authors developed multiple tumor mRNA markers for reverse transcriptase-polymerase chain reaction (RT-PCR) to detect metastatic tumor cells in the blood and tissue of patients with American Joint Committee on Cancer (AJCC) Stage II/III or IV pancreatic carcinoma.

METHODS

An RT-PCR plus Southern blot assay was used to detect mRNA of tumor markers in blood and tissues. mRNA expression of the tumor progression markers MET (hepatocyte growth factor receptor gene c-met), GalNAc-T (beta1,4- N-acetyl-galactosaminyl-transferase), and beta-hCG (beta-human chorionic gonadotropin) was evaluated in 9 pancreatic carcinoma cell lines, 13 tumor biopsy specimens, 5 nonmalignant pancreatic tissue specimens, and blood from 33 pancreatic carcinoma patients and 32 healthy donors.

RESULTS

The detection limit of the assay was 1 rhog, 10 rhog, and 10 rhog for MET, GalNAc-T, and beta-hCG mRNA expression, respectively. The pancreatic carcinoma cell lines expressed all three mRNA markers. Of blood specimens from 17 patients with AJCC Stage IV pancreatic carcinoma, 82%, 65%, and 76% were MET, GalNAc-T, and beta-hCG mRNA positive, respectively. Of blood specimens from 16 patients with AJCC Stage II/III disease, 88% were positive for at least 1 mRNA marker.

CONCLUSIONS

A multiple molecular marker assay was developed to detect cancer cells in blood and tissue from patients with different stages of pancreatic carcinoma. The detection of cancer cells in the blood may be used as a marker of pancreatic tumor progression and may be useful in monitoring response to therapy.

Functional interleukin 4 receptor and interleukin 2 receptor common gamma-chain on human non-small cell lung cancers: novel targets for immune therapy

OBJECTIVE

The interleukin 4 receptor has been demonstrated on the surface of human non-small cell lung carcinoma cell lines and tumor specimens. Interleukin 4 causes G1-phase cell-cycle arrest of non-small cell lung cancer cell lines expressing the interleukin 4 receptor; the effect directly correlates with the expression of the interleukin 4 receptor and is seen within 48 hours after treatment. We examined signal transduction pathways used by the interleukin 4 receptor that may account for growth arrest of the cell line LUst but had no effect on another non-small cell lung cancer cell line, SK-MES-1.

METHODS

Western blot analysis was performed on both LUst and SK-MES-1 cell lines cultured in the presence of interleukin 4 (500 U/mL). Cells were lysed, protein extracted, and electroblotted; blots were then probed with murine monoclonal antibodies to specific intracellular proteins.

RESULTS

Western blotting of the cell lines with antiphosphotyrosine antibody (4G10) demonstrated multiple (140 kd, 100-130 kd, and 65 kd) phosphoproteins seen only in the interleukin 4-treated LUst cell line and not observed in the SK-MES-1 cell lines. Immunoprecipitation and blotting of the LUst cell line with specific secondary antibodies demonstrated that the 140-kd phosphoprotein was the interleukin 4 receptor, the 130-kd phosphoprotein was Janus kinase 1, the 116-kd phosphoprotein was Janus kinase 3, and the 65-kd phosphoprotein was the interleukin 2 receptor gamma-chain. Specific binding was not observed in the non-small cell lung cancer cell line SK-MES-1, suggesting that a functional interleukin receptor gamma-chain was not present. Southern blotting with complementary DNA probes to interleukin 2 receptor gamma-chain confirmed the absence of this receptor on cell line SK-MES-1.

CONCLUSIONS

These results suggest that non-small cell lung cancer cells may express functional cytokine receptors, including the interleukin 2 receptor gamma-chain commonly found in association with the lymphocyte interleukin 2 receptor. These receptors may be novel targets for directing cytokine-based immune therapy.

RNA melanoma vaccine: induction of antitumor immunity by human glycoprotein 100 mRNA immunization

An RNA melanoma vaccine was investigated to induce protective immunity in a mouse-melanoma model. LacZ mRNA was synthesized in vitro by pSFV3 expression vector and introduced into the spleen of mice, using HVJ-liposomes. A high level of beta-galactosidase activity was detected for 10 days in mouse spleen. The human melanoma-associated antigen gp100 mRNA was synthesized in vitro by pSFV3 vector and encapsulated in HVJ-liposomes. Immunization by direct injection of the gp100 mRNA HVJ-liposomes into mouse spleen induced both anti-gp100 Ab and CTL responses against B16 melanoma. Immunization by administration of gp100 mRNA into the spleen delayed tumor growth and significantly prolonged survival compared with control treated mice. These preclinical studies demonstrate that an RNA tumor antigen vaccine strategy has potential application for human cancer treatment and prevention.