A first-in-class, first-in-human, phase I trial of p28, a non-HDM2-mediated peptide inhibitor of p53 ubiquitination in patients with advanced solid tumours.

BACKGROUND: This first-in-human, phase I clinical trial of p28 (NSC745104), a 28-amino-acid fragment of the cupredoxin azurin, investigated the safety, tolerability, pharmacokinetics and preliminary activity of p28 in patients with p53(+) metastatic solid tumours. METHODS: A total of 15 patients were administered p28 i.v. as a short infusion three times per week for 4 weeks followed by a 2-week rest under an accelerated titration 3+3 dose escalation design until either a grade 3-related adverse event occurred or the maximum tolerated dose (MTD) was reached. Single-dose and steady-state serum pharmacokinetics were characterised. Assessments included toxicity, best objective response by RECIST 1.1 Criteria, and overall survival. RESULTS: No patients exhibited any dose-limiting toxicities (DLTs), significant adverse events or exhibited an immune response (IgG) to the peptide. The No Observed Adverse Effect Level (NOAEL) and MTD were not reached. Seven patients demonstrated stable disease for 7-61 weeks, three a partial response for 44-125 weeks, and one a complete response for 139 weeks. Three patients are still alive at 158, 140, and 110 weeks post therapy completion. CONCLUSION: p28 was tolerated with no significant adverse events. An MTD was not reached. Evidence of anti-tumour activity indicates a highly favourable therapeutic index and demonstrates proof of concept for this new class of non-HDM2-mediated peptide inhibitors of p53 ubiquitination.

Resveratrol inhibits rhabdomyosarcoma cell proliferation.

Rhabdomysarcoma is the most common soft tissue tumour in children under the age of 15. Although the introduction of multimodal treatment programmes, including chemotherapy, radiation therapy and excision have increased the overall survival, the chemotherapeutic agents currently used for the treatment of rhabdomyosarcoma exhibit considerable toxicity. The aim of this study was to investigate the effects and possible mechanism(s) of action of resveratrol on human embryonal rhabdomyosarcoma (RD) cells. Resveratrol is a natural polyphenolic compound produced in a number of edible plants and has received considerable attention as a potential chemopreventive and/or chemotherapeutic agent against various types of cancers. In the present study, resveratrol was shown to inhibit cell proliferation of RD cells in a dose-dependent manner with an IC50 of 48.1 micromol/l and induce an arrest in the S/G2 phase of the cell cycle. As evident from immunocytochemical data, resveratrol treatment increased the size of the RD cells. Furthermore, resveratrol treatment resulted in a significant downregulation of cyclin B expression as demonstrated by western blot analyses. In conclusion, the present study shows that resveratrol exerts a strong inhibition of rhabdomyosarcoma cell proliferation in part by arresting cells in S/G2 phase of the cell cycle. These findings warrant further investigation to establish potential use of resveratrol as a relatively non-toxic chemotherapeutic agent for the treatment of rhabdomyosarcoma.

The bacterial redox protein azurin induces apoptosis in J774 macrophages through complex formation and stabilization of the tumor suppressor protein p53.

Two redox proteins, azurin and cytochrome c(551) elaborated by Pseudomonas aeruginosa, demonstrate significant cytotoxic activity towards macrophages. Azurin can enter macrophages, localize in the cytosol and nuclear fractions, and induce apoptosis. Two redox-negative mutants of azurin have less cytotoxicity than does wild-type (wt) azurin. Azurin has been shown to form a complex with the tumor suppressor protein p53, a known inducer of apoptosis, thereby stabilizing it and enhancing its intracellular level. A higher level of reactive oxygen species (ROS), generated during treatment of macrophages with wt azurin, correlates with its cytotoxicity. Treatment with some ROS-removing antioxidants greatly reduces azurin-mediated cytotoxicity, thus demonstrating a novel virulence property of this bacterial redox protein.

In vitro transformation of human congenital naevus to malignant melanoma.

The incidence of melanoma is estimated to be growing at the second fastest rate among all cancers in the United States. The progression of the melanocyte to a malignant melanoma involves various sequential steps: development of benign naevocellular naevus, preneoplastic dysplastic naevus, primary melanoma, and metastatic melanoma. Despite these clearly defined stages, very little is known about the molecular events leading to melanoma progression. We established a human congenital naevus cell line (UISO-CMN-1). UISO-CMN-1 cells were confirmed to have melanocytic origin by S100 immunoreactivity and the presence of melanin granules and melanosomes. UISO-CMN-1 cells, even though they showed structural and numerical abnormalities in karyotype, were non-tumorigenic when transplanted into athymic mice. However, following frequent exposure to ultraviolet C radiation, UISO-CMN-1 cells acquired tumorigenic potential. Transformation of UISO-CMN-1 cells into tumorigenic cells was accompanied by induction of ganglioside-2 expression without any significant changes in cellular ganglioside-3. These transformed and non-transformed UISO-CMN-1 cell lines can serve as excellent research tools for studying the molecular changes associated with melanoma development and progression, and for identifying agents that might prevent development of malignant melanoma.

Betulinic acid reduces ultraviolet-C-induced DNA breakage in congenital melanocytic naeval cells: evidence for a potential role as a chemopreventive agent.

Melanoma transformation progresses in a multistep fashion from precursor lesions such as congenital naevi. Exposure to ultraviolet (UV) light promotes this process. Betulinic acid (BA) was identified by our group as a selective inhibitor of melanoma that functions by inducing apoptosis. The present study was designed to investigate the effect of BA and UV-C (254 nm) on cultured congenital melanocytic naevi (CMN) cells, using the single-cell gel electrophoresis (comet) assay to detect DNA damage. Exposure to UV light induced a 1.7-fold increase in CMN cells (P = 0.008) when compared with controls. When a p53 genetic suppressor element that encodes a dominant negative polypeptide (termed GSE56) was introduced into the CMN cells, the transfected cells were more sensitive to UV-induced DNA breakage. This suggests that p53 can protect against UV-induced DNA damage and subsequent melanoma transformation. Pretreatment with BA (3 microm) for 48 h resulted in a 25.5% reduction in UV-induced DNA breakage in the CMN cells (P = 0.023), but no changes were observed in the transfected cells. However, Western blot analysis revealed no changes in the p53 or p21 levels in BA-treated cells, suggesting that BA might mediate its action via a non-p53 pathway. These data indicate that BA may have an application as a chemopreventive agent in patients with congenital naevi.

A novel use for the comet assay: detection of topoisomerase II inhibitors.

BACKGROUND: The simple and quick comet assay can quantitatively detect DNA cleavage in cells. This study aimed to determine whether the comet assay could be used to detect topoisomerase (topo) II inhibitors. MATERIALS AND METHODS: HT-29 colon cancer cells were pre-incubated with aclarubicin, a topo II antagonist, then treated with topo II poisons: etoposide (VP-16), teniposide (VM-26), 4'-(acridinylamino) methansulfon-m-anisidide (m-AMSA) and adriamycin (doxorubicin). We also tested a topo I poison (camptothecin) and a microtubule depolymerization inhibitor (taxol). RESULTS: Aclarubicin significantly reduced DNA cleavage induced by topo II poisons, but not that induced by camptothecin. In HL-60/MX2 cells (containing no topo II beta and reduced topo II alpha), DNA breakage induced by topo II poisons was lower. Also, aclarubicin antagonized topo I-mediated camptothecin-induced DNA cleavage in these resistant cells. CONCLUSIONS: The comet assay can be used to detect topo II poisons in cultured cells. Also, aclarubicin has a dual topo I and topo II antagonism, with "preferential antagonism" of topo II when topo II beta catalytic activity is normally expressed.

Micropthalmia transcription factor: a new prognostic marker in intermediate-thickness cutaneous malignant melanoma.

Micropthalmia transcription factor (Mitf) is involved in melanocyte development and differentiation. The current study was undertaken to determine whether there is a relationship between Mitf expression and survival in patients with intermediate-thickness (1.0-4.0 mm) melanoma. Original paraffin blocks or slides of the primary tumor were accessible in 63 such patients. Mitf expression was evaluated by immunocytochemistry and analyzed visually. Slides were graded as follows according to the percentage of cells whose nuclei stained positive for Mitf: (a) 0, 0%; (b) +1, 1-25%; (c) +2, 26-50%; (d) +3, 51-75%; and (e) +4, > 75%. Median follow-up was 50 months. Mean thickness was 2.2 +/- 0.7 mm. Mean overall survival was 171.90 +/- 13.12 months. Mean disease-free survival was 168.53 +/- 13.96 months. Fifty-two melanomas (82.5%) stained positive for Mitf. By univariate analysis, mean overall survival and disease-free survival in patients whose melanomas did not express Mitf were 80.89 +/- 17.98 months (median, 51 months) and 71.36 +/- 19.87 months (median, 40 months), respectively. This compares with 187.90 +/- 13.41 months (median, not reached) and 186.78 +/- 13.84 months (median, not reached), respectively, for patients whose melanomas expressed Mitf (P = 0.0086 and P = 0.0054). These findings persisted in multivariate analysis. In addition, patients with > 50% Mitf expression had significantly fewer nodal metastases after node dissection than patients with < or = 50% Mitf expression (P = 0.04). Our data suggest that Mitf may be a new molecular prognostic marker in patients with intermediate-thickness melanoma.

Engineering and characterization of a single-chain antibody fragment (scFV1924) against the human sarcoma-associated antigen p102.

BACKGROUND: Monoclonal Antibody (MAb) 19-24 against the human sarcoma-associated antigen (SAA) p102 was previously characterized, and it demonstrated potential for sarcoma immunodiagnosis and immunotherapy. Due to the limitations of using intact murine MAbs in human clinical settings, we engineered a single-chain antibody fragment of MAb 19-24 (scFV1924). MATERIALS AND METHODS: Monoclonal Antibody (MAb) 19-24 against the human sarcoma-associated antigen (SAA) p102 was previously characterized, and it demonstrated potential for sarcoma immunodiagnosis and immunotherapy. Due to the limitations of using intact murine MAbs in human clinical settings, we engineered a single-chain antibody fragment of MAb 19-24 (scFV1924). RESULTS: The results from competition radioimmunoassay showed that binding of MAb 19-24 to SAA p102 on sarcoma cell membranes was inhibited by scFV1924. CONCLUSIONS: This indicates the potential of further application of the scFV1924 in human sarcoma immunotherapy.

Induction of differentiation by 1alpha-hydroxyvitamin D(5) in T47D human breast cancer cells and its interaction with vitamin D receptors.

The role of the active metabolite of vitamin D, 1,25 dihydroxyvitamin D(3) (1,25(OH)(2)D(3)), in cell differentiation is well established. However, its use as a differentiating agent in a clinical setting is precluded due to its hypercalcaemic activity. Recently, we synthesised a relatively non-calcaemic analogue of vitamin D(5), 1alpha-hydroxyvitamin D(5) (1alpha(OH)D(5)), which inhibited the development of carcinogen-induced mammary lesions in culture and suppressed the incidence of chemically induced mammary carcinogmas in rats. In the present study, we determined the differentiating effects of 1alpha-(OH)D(5) in T47D human breast cancer cells and compared its effects with 1,25(OH)(2)D(3). Cells incubated with either 10 or 100 nM of the analogues inhibited cell proliferation in a dose-dependent manner, as measured by the dimethylthiazolyl-2,5-diphenyltetrazolium bromide (MTT) assay. Similar growth-inhibitory effects were also observed for MCF10(neo) cells. Both vitamin D analogues induced cell differentiation, as determined by induction of casein expression and lipid production. However, MCF10(neo) cells failed to respond to either vitamin D analogue and did not undergo cell differentiation. Since the cell differentiating effect of vitamin D is considered to be mediated via the vitamin D receptor (VDR), we examined the induction of VDR using reverse transcriptase-polymerase chain reaction (RT-PCR) in both cells. The results showed that, in T47D cells, both 1,25(OH)(2)D(3) and 1alpha(OH)D(5) induced VDR in a dose-dependent manner. Moreover, both analogues of vitamin D upregulated the expression of vitamin D response element-chloramphenicol acetyl transferase (VDRE-CAT). These results collectively indicate that 1alpha-(OH)D(5) may mediate its cell-differentiating action via VDR in a manner similar to that of 1,25(OH)(2)D(3).

Genistein induces apoptosis and topoisomerase II-mediated DNA breakage in colon cancer cells.

The present study was undertaken to determine if (a) genistein induces topo II-mediated DNA damage in HT-29 colon cancer cells; and (b) if this damage is required to induce apoptosis. DNA damage was evaluated using the comet assay. Apoptosis was determined by the ethidium bromide/acridine orange staining technique. DNA breakage was noted within 1 h of treatment. Apoptosis was only induced with high concentrations (>/=60 microM) of genistein. Marked inhibition of HT-29 cell growth was evident at concentrations ranging from 60 to 150 microM. This was associated with a cell cycle arrest at G(2)/M. Similar findings were obtained in SW-620 and SW-1116 colon cancer cell lines. Aclarubicin, a topo II antagonist, reduced genistein-induced DNA breaks but did not reduce apoptosis. These data suggest that, in colon cancer cells, topo II serves as the enzymatic target of genistein. Furthermore, topo II-mediated DNA cleavage is not required for the induction of apoptosis.

Determination of betulinic acid in mouse blood, tumor and tissue homogenates by liquid chromatography-electrospray mass spectrometry.

A rapid and sensitive high-performance liquid chromatography-electrospray MS method has been developed to determine tissue distribution of betulinic acid in mice. The method involved deproteinization of these samples with 2.5 volumes (v/w) of acetonitrile-ethanol (1:1) and then 5 microl aliquots of the supernatant were injected onto a C18 reversed-phase column coupled with an electrospray MS system. The mobile phase employed isocratic elution with 80% acetonitrile for 10 min; the flow-rate was 0.7 ml/min. The column effluent was analyzed by selected ion monitoring for the negative pseudo-molecular ion of betulinic acid [M-H]- at m/z 455. The limit of detection for betulinic acid in biological samples by this method was approximately 1.4 pg and the coefficients of variation of the assay (intra- and inter-day) were generally low (below 9.1%). When athymic mice bearing human melanoma were treated with betulinic acid (500 mg/kg, i.p.), distribution was as follows: tumor, 452.2 +/- 261.2 microg/g; liver, 233.9 +/- 80.3 microg/g; lung, 74.8 +/- 63.7 microg/g; kidney, 95.8 +/- 122.8 microg/g; blood, 1.8 +/- 0.5 microg/ml. No interference was noted due to endogenous substances. These methods of analysis should be of value in future studies related to the development and characterization of betulinic acid.

Molecular prognostic markers in intermediate-thickness cutaneous malignant melanoma.

BACKGROUND: The limitations of morphologic criteria alone in determining the prognosis for a patient with a particular intermediate-thickness primary melanoma have prompted efforts to identify other markers. METHODS: In this study, the authors analyzed expression of p53, beta1 integrin, and beta3 integrin in primary tumors from 111 patients with intermediate-thickness malignant melanoma. RESULTS: Eighty-nine (80%) had detectable p53 protein, 58 (52%) expressed beta1 integrin, and 71 (64%) expressed beta3 integrin. Patients with beta3 positive melanomas were more likely to die of their disease (32 of 71 patients, 45%) than those with beta3 negative tumors (3 of 40 patients, 8%) (P < 0.0001). The number of involved lymph nodes, Clark's level, beta1 integrin expression, thickness, and mitotic rate also had prognostic significance. beta3 integrin was associated with subsequent lung metastases and beta1 integrin with lymph node involvement. CONCLUSIONS: Integrin expression, along with histopathologic criteria, is a prognostic marker for intermediate-thickness malignant melanoma and may indicate the site of subsequent metastasis. These observations may have clinical utility and suggest areas for future investigation.

Molecular analysis of 1p36 breakpoints in two Merkel cell carcinomas.

Merkel cell carcinoma (MCC) is a rare aggressive neuroendocrine tumor of the skin. Only little information is available on the genetic alterations occurring in this tumor. Cytogenetic studies thus far have not shown recurrent chromosomal changes, although various structural chromosome 1 rearrangements, including deletions, often leading to loss of distal 1p material appear to be frequent. We report on fluorescence in situ hybridization and loss of heterozygosity analyses of an MCC tumor and MCC cell line UISO. The present study has shown that two distinct regions in the most distal band 1p36 on the short arm of chromosome 1 can be implicated in MCC. One region at 1p36.3 was delineated by a distal deletion in the MCC tumor as a result of an unbalanced translocation, resulting in loss of all markers distal to ENO1. This region was previously shown to be deleted in different tumor types including neuroblastoma. In cell line UISO an insertion in 1p36.2 was identified. The insertion breakpoint indicates a second, more proximal, region on 1p involved in MCC. The insertion breakpoint was mapped within a cluster of repetitive tRNA and snRNA genes and thus could coincide with the constitutional 1p36 breakpoint previously reported in a patient with neuroblastoma.

Plasma c-erbB-2 levels in breast cancer patients: prognostic significance in predicting response to chemotherapy.

PURPOSE: To determine the significance of plasma c-erbB-2 levels to assess the extent of disease spread and to predict the response to chemotherapy in node-positive breast cancer patients. METHODS: We determined plasma levels of c-erbB-2 in 79 stages II and III breast cancer patients who received cyclophosphamide, methotrexate, and flourouracil (CMF)/cyclophosphamide, methotrexate, fluorouracil, vincristine, and prednisone (CMFVP) chemotherapy. All patients had a minimum follow-up of greater than 60 months or until disease recurrence. Plasma samples were obtained before and after chemotherapy. Plasma c-erbB-2 levels were quantified by enzyme-linked immunoassay. c-erbB-2 levels were analyzed in relation to the patients' axillary lymph node status, menopausal status, disease status, disease-free survival (DFS), and steroid receptor status of tumor. RESULTS: Plasma c-erbB-2 levels varied widely in breast cancer patients. In general, when all patients were included in the analyses, plasma c-erbB-2 levels before chemotherapy correlated significantly with the number of positive axillary lymph nodes and with postchemotherapy c-erbB-2 levels. No association was observed between pre- or postchemotherapy c-erbB-2 levels and other variables (patients' age at diagnosis, receptor status of the tumor, or disease status). The prognostic significance of different factors (ie, nodal status [one to three v > three positive nodes], menopausal status [pre- v postmenopausal women], estrogen receptor [ER] status [ER+ v ER-], and pre- and postchemotherapy c-erbB-2 levels) in predicting DFS was determined in all study patients. Among the variables examined, nodal status was the strongest predictor of DFS in these patients. The second most significant prognostic marker was postchemotherapy c-erbB-2 level. Prechemotherapy c-erbB-2 levels showed prognostic significance for DFS in a subset of breast cancer patients (ie, patients with > three positive nodes). Patients with greater than three positive lymph nodes and those with greater than 100 fmol/mL of plasma c-erbB-2 levels before therapy had significantly shorter DFS than did those patients with 100 fmol/mL or less c-erbB-2 levels. CONCLUSION: In breast cancer patients, determination of c-erbB-2 levels before therapy is an important biomarker to assess the extent of disease spread in the lymph nodes. Postchemotherapy c-erbB-2 levels are also a prognostic indicator for DFS in patients who receive chemotherapy. Finally, in a subgroup of patients with greater than three positive nodes, prechemotherapy c-erbB-2 levels are a prognostic marker for response of patients to standard chemotherapy.

Surgery for metastatic melanoma.

The appearance of distant metastases in a patient with malignant melanoma usually prophesies an early death: median survival is only 5 to 8 months. Surgery definitely can palliate certain patients and lead to a prolongation of life for others. In selected surgical candidates, an isolated nonvisceral metastasis, complete resection with free surgical margins, and a longer disease-free interval all favorably affect prognosis. In such cases, median survival can even approach 10 years, with a 5-year survival of up to 35%. Lung metastases are often incidental findings, but if complete resection can be accomplished, sometimes a median survival of 19 months and a 5-year 25% survival can be seen. Patients rarely survive long-term after brain or gastrointestinal metastases present themselves, but surgical resection extends median survival to about 10 months in this group with a significant improvement in quality of life. General guidelines should be reasonably applied for surgical intervention, with each metastatic melanoma patient given special individual assessment. Little has changed since the topic of the surgical role in metastatic melanoma was last reviewed in this journal by Coit in 1993.

Development of a new metastatic human breast carcinoma xenograft line.

Xenografts originated from human tumours offer the most appropriate research material for in vivo experimental research. However, primary human breast carcinomas are difficult to grow when transplanted in athymic mice: tumour take is less than 15%. Recently, we have achieved 60% tumour take by injecting tumour cell suspensions mixed with Matrigel. Human breast xenografts originated from primary breast carcinoma also frequently show the potential to metastasize spontaneously. In the present study, we generated a human breast carcinoma xenograft line (UISO-BCA-NMT-18) that shows 100% tumorigenicity and 80-100% lung metastasis when transplanted s.c. in athymic mice. We have studied in detail the characteristics of the xenograft and the patient's tumour from which the xenograft line originated. Both the xenograft and the patient's tumour showed intense staining for mutant p53 nuclear protein, and high expression of U-PA, PAI and u-PAR. In vivo growth of the xenograft is stimulated by exogenous supplementation of oestrogen. This xenograft is continuously growing in mice and has shown 80-100% metastasis for the last three successive in vivo passages. This well-characterized, oestrogen-responsive, metastatic breast carcinoma xenograft line will provide excellent research material for metastasis-related research.

Evaluation of newer prognostic markers for adult soft tissue sarcomas.

PURPOSE: In addition to tumor size, grade, location, and the presence of metastases, other factors may be useful in prognostication for adults with soft tissue sarcoma (STS). This study examines the relationship of MDR-1 mRNA, p-glycoprotein (P-gp), Ki-67 expression, and DNA content expression to clinical outcome in adults with STS. PATIENTS AND METHODS: Snap-frozen STS specimens from 65 patients were analyzed and compared with clinical outcomes. Immunohistochemistry was performed for the Ki-67 antigen and P-gp. DNA content was determined using the Feulgen reaction and quantitated using image analysis. MDR-1 mRNA expression was determined using a reverse-transcriptase polymerase chain reaction (RT-PCR)-based assay. RESULTS: P-glycoprotein expression was found by immunohistochemistry in 48% of cases with 5-year overall (54% v 14%, P = .07) and disease-free survival rates (32% v 18%, P = .039) higher in high-grade tumors that did not express P-gp. MDR-1 mRNA was detected in 51% of cases and no patient with high levels of MDR-1 mRNA expression was a long-term survivor. Patients with diploid tumors had significantly better survival than those with nondiploid tumors (51% v 31%, P = .03). High levels of Ki-67 were associated with poorer overall survival (46% v 31%, P = .04). On multivariate analysis, American Joint Committee on Cancer (AJCC) staging, DNA content, Ki-67, and P-gp staining were significant prognostic factors for 5-year overall and disease-free survival. CONCLUSION: P-gp expression, high-level Ki-67 expression, and nondiploid DNA content are independent prognostic indicators that correlate with poor outcomes in STS patients. However, MDR-1 mRNA was not found to be predictive of survival. These newer markers are useful additions to AJCC staging for prognostication for patients with STS. Such markers may be useful in selecting high-risk STS patients who could benefit from systemic adjuvant therapy.

Phase I evaluation of interleukin-2-transfected irradiated allogeneic melanoma for the treatment of metastatic melanoma: appendix 1: protocol.

A cell line (UISO-H-MEL-2) was established from the neoplastic cells of a patient with malignant melanoma during the natural course of the patient's treatment. The melanoma cells express defined MHC Class I histocompatibility determinants including determinants specified by the HLA-A2 Class I allele, along with a common melanoma-associated T-cell epitope derived from the tyrosinase gene. The gene for human interleukin-2 (IL-2) was transduced into the cells with a provirus (pZipNeoSVIL-2), packaged in GP + envAM12 cells. Integration of the IL-2 gene into genomic DNA of the transduced cells and its expression were established. The IL-2-secreting cell line (UISO-H-MEL-2-IL-2) was found to be free of recombinant retroviruses and other infectious agents. The IL-2-secreting cells will be subjected to 5000 rads X-irradiation and administered to 12 informed patients with metastatic malignant melanoma in a Phase I toxicity study. The dose of X-irradiation was sufficient to inactivate one hundred percent of the cells, but insufficient to completely inhibit IL-2 synthesis during a fourteen-day period of analysis. Patients who have failed all standard forms of treatment will become eligible for inclusion in the study if they develop metastatic melanoma, and if their tumor cells express products of the tyrosinase gene. The patients will differ with the cellular immunogen at no less than three of six MHC Class I alleles, but will share identity at the HLA-A2 Class I allele. The patient's antimelanoma immune response to the injected cells will be determined by both in vivo and in vitro parameters. Background studies performed in inbred mice indicate that X-irradiated IL-2-secreting cells that express both melanoma-associated antigens and allogeneic Class I histocompatibility antigens are more antigenic in terms of their capacity to induce an antimelanoma response than X-irradiated IL-2-secreting melanoma cells. Of significance for the future potential of this form of therapy in melanoma patients, the period of survival of mice was established melanoma treated with the IL-2-secreting allogeneic cells was significantly (P < 0.001) longer than that of untreated animals, or animals treated with X-irradiated melanoma cells. An analogous protocol was reviewed and approved by the Recombinant DNA Advisory Committee of the National Institutes of Health.

Molecular cloning and primary characterization of a single-chain antibody against human sarcoma-associated antigen p200.

BACKGROUND: Monoclonal Antibody (MAb) 29-13 reacts with the human sarcoma-associated antigen (SAA) p200. We report here engineering and primary characterization of a single chain antibody (scFV2913). MATERIALS AND METHODS: The scFV2913 recombinant gene, consisting of VH-linker-VK, was constructed with RT-PCR. This gene was cloned and expressed in E. coli. The renatured scFV2913 was used in the immunostaining study. RESULTS: Consistent with its parent MAb 29-13, purified and renatured scFV2913 showed affinity and specificity to the SAA p200 according to the immuno-histochemical staining study of 99 specimens of human sarcomas and other tissues. CONCLUSIONS: Due to its retained specificity and affinity, scFV2913 may be useful in immunodiagnosis and immunotherapy for sarcoma patients.

Overexpression of EGF receptor is associated with spontaneous metastases of a human melanoma cell line in nude mice.

Twelve human melanoma cell lines were analyzed for alterations in the epidermal growth factor receptor (EGFR) gene at the DNA, RNA and protein levels. EGFR expression of the cell lines was then correlated with their previously reported p53 expression, in vivo growth characteristics, and rate of metastases in athymic mice. Northern blot and immunocytochemical analyses demonstrated low to intermediate levels of EGF receptor expression in four cell lines. Overexpression of EGFR was seen in one cell line, UISO-MEL-6. Although no significant statistical difference was observed between in vivo growth of EGFR-positive cell lines versus EGFR-negative cell lines, UISO MEL-6 which also lacked p53 expression, had the fastest in vivo rate of growth and was the only cell line to produce visceral metastases following subcutaneous inoculation in nude mice. Furthermore, EGFR overexpression in UISO-MEL-6 was associated with alterations of the gene at the DNA level.