Tumors Of Various Origins Research Articles

Inducible Hsp70 as target of anticancer immunotherapy: Identification of HLA-A*0201-restricted epitopes.

The design of a broad application tumor vaccine requires the identification of tumor antigens expressed in a majority of tumors of various origins. We questioned whether the major stress-inducible heat shock protein Hsp70 (also known as Hsp72), a protein frequently overexpressed in human tumors of various histological origins, but not in most physiological normal tissues, constitutes a tumor antigen. We selected the p391 and p393 peptides from the sequence of the human inducible Hsp70 that had a high affinity for HLA-A*0201. These peptides were able to trigger a CTL response in vivo in HLA-A*0201-transgenic HHD mice and in vitro in HLA-A*0201+ healthy donors. p391- and p393-specific human and murine CTL recognized human tumor cells overexpressing Hsp70 in a HLA-A*0201-restricted manner. Tetramer analysis of TILs showed that these Hsp70 epitopes are targets of an immune response in many HLA-A*0201+ breast cancer patients. Hsp70 is a tumor antigen and the Hsp70-derived peptides p391 and p393 could be used to raise a cytotoxic response against tumors of various origins.

Identification and characterisation of GPR100 as a novel human G-protein-coupled bradykinin receptor.

G-protein-coupled receptor 100 (GPR100) was discovered by searching the human genome database for novel G-protein-coupled peptide receptors. Full-length GPR100 was amplified from a cDNA library of the neuroendocrine cell line BON, which is derived from a human pancreas carcinoid. The open-reading frame, present on a single exon, coded for a protein of 374 amino acids with highest sequence identity (43%) to the human orphan somatostatin- and angiotensin-like peptide receptor. The analysis of chromosomal localisation mapped the GPR100 gene to chromosome 1q21.2-q21.3. The stable expression of GPR100 in Chinese hamster ovary cells together with aequorin as calcium sensor and the promiscuous G-protein subunit alpha16 as signal transducer revealed bradykinin and kallidin as effectors to elicit a calcium response. Dose-response curves yielded EC50 values for both ligands in the low nanomolar range, while the respective analogues without arginine at the carboxy-terminus were inactive. Calcium mobilisation was inhibited by the phospholipase C blocker U73122, but not by pertussis toxin, suggesting the involvement of the G-protein subunit alphaq and not alphai or alphao in signal transduction. In line with the main function of kinins as peripheral hormones, we found that GPR100 was expressed predominantly in tissues like pancreas, heart, skeletal muscle, salivary gland, bladder, kidney, liver, placenta, stomach, jejunum, thyroid gland, ovary, and bone marrow, but smaller amounts were also detected in the brain and in cell lines derived from tumours of various origins.

Application of Mesothelin Immunostaining in Tumor Diagnosis

Mesothelin is a differentiation antigen that was first described as the antigenic target of the monoclonal antibody K1. Using this antibody, it was demonstrated that mesothelin is strongly expressed in normal mesothelial cells, mesotheliomas, nonmucinous ovarian carcinomas, and some other malignancies. Immunostaining with the K1 antibody was suggested to be useful in the diagnosis of mesothelioma in the early 1990s. This, however, could not be further explored until recently because of the lack of commercially available anti-mesothelin antibodies. In a recent investigation by this author, all epithelioid mesotheliomas and about 40% of the lung adenocarcinomas reacted with the 5B2 anti-mesothelin antibody, which has only recently become commercially available. It was concluded that immunostaining with this antibody has limited value in discriminating between these conditions. The aim of the current study was to further investigate the potential application of the 5B2 antibody in tumor diagnosis. Mesothelin expression was evaluated in formalin-fixed, paraffin-embedded samples of normal tissues and in 471 tumors of various origins. The carcinomas that most frequently exhibited strong mesothelin reactivity were nonmucinous carcinomas of the ovary (14 of 14 serous, 3 of 3 endometrioid, 6 of 8 clear cell, and 4 of 4 transitional cell carcinoma), and adenocarcinomas of the pancreas (12 of 14), the ampulla of Vater (3 of 3), endometrium (7 of 11), lung (14 of 34), and liver (7 of 19 cholangiocarcinomas). The carcinomas that did not express mesothelin included renal cell carcinomas, hepatomas, carcinomas of the thyroid, adrenal cortical carcinomas, prostatic adenocarcinomas, and carcinoid tumors. All germ cell tumors, with the exception of teratomas, were consistently negative for mesothelin. Because of the strong mesothelin expression in nonmucinous carcinomas of the ovary, but not in a variety of tumors with which these lesions may be confused (eg, clear cell carcinoma of the ovary versus endodermal sinus tumor or renal cell carcinoma, clear cell type; transitional cell carcinoma of the ovary versus TCC of the urinary tract), immunostaining for this marker could be useful in establishing the differential diagnosis. The strong mesothelin expression in the large majority of pancreatic ductal adenocarcinomas (12 of 14), but not in normal pancreas, confirms that this marker may have some diagnostic utility in discriminating between neoplastic and nonneoplastic pancreatic ductal epithelium. The mesothelin expression in about one-third of the cholangiocarcinomas, but not in hepatomas, suggests that this marker may have some utility in distinguishing between these two malignancies when they are poorly differentiated. In the group of small round blue cell tumors, only desmoplastic small round cell tumors exhibited mesothelin positivity (7 of 12). Of the soft tissue tumors, only the epithelial component of biphasic synovial sarcomas (9 of 9) expressed mesothelin. These findings indicate that, in some instances, mesothelin immunostaining can assist in the diagnosis of these tumors. Finally, the strong mesothelin reactivity seen in the adenomatoid tumors (3 of 3) provides further support for a mesothelial derivation for this lesion.

Cancer gene therapy with tissue inhibitors of metalloproteinases (TIMPs).

Matrix metalloproteinases (MMPs) are of crucial importance for the invasive behavior of primary tumors and their metastases. MMP activity is regulated by the four naturally occurring tissue inhibitors of metalloproteinases (TIMPs). It has been shown that overexpression of TIMPs in tumors of various origins leads to reduced tumor growth and formation of metastases. More recently, antitumor efficacy by in vivo gene transfer of TIMPs has been reported in several clinically relevant animal models. This review analyses the therapeutic potential of the TIMPs from a cancer gene therapeutic point of view with particular emphasis on cell culture and in vivo data.

Spectrum of hSNF5/INI1 somatic mutations in human cancer and genotype-phenotype correlations.

The hSNF5/INI1 gene which encodes a member of the SWI/SNF chromatin ATP-dependent remodeling complex, is a new tumor suppressor gene localized on chromosome 22q11.2 and recently shown to be mutated in malignant rhabdoid tumors. We have searched for hSNF5/INI1 mutations in 229 tumors of various origins using a screening method based on denaturing high-performance liquid chromatography. A total of 31 homozygous deletions and 36 point alterations were identified. Point mutations were scattered along the coding sequence and included 15 nonsense, 15 frameshift, three splice site, two missense and one editing mutations. Mutations were retrieved in most rhabdoid tumors, whatever their sites of occurrence, indicating the common pathogenetic origin of these tumors. Recurrent hSNF5/INI1 alterations were also observed in choroid plexus carcinomas and in a subset of central primitive neuroectodermal tumors (cPNETs) and medulloblastomas. In contrast, hSNF5/INI1 point mutations were not detected in breast cancers, Wilms' tumors, gliomas, ependymomas, sarcomas and other tumor types, even though most analyzed cases harbored loss of heterozygosity at 22q11.2 loci. These results suggest that rhabdoid tumors, choroid plexus carcinomas and a subset of medulloblastomas and cPNETs share common pathways of oncogenesis related to hSNF5/INI1 alteration and that hSNF5/INI1 mutations define a genetically homogeneous family of highly aggressive cancers mainly occurring in young children and frequently, but not always, exhibiting a rhabdoid phenotype.

Down-regulation of the MHC class I antigen-processing machinery after oncogenic transformation of murine fibroblasts.

Malignant transformation is often associated with genetic alterations providing tumor cells with mechanisms for escape from immune surveillance. Human and murine tumors of various origin as well as in vitro models of viral and oncogenic transformation express reduced levels of major histocompatibility complex (MHC) class I antigens resulting in decreased sensitivity to MHC class I-restricted cytotoxic T lymphocyte (CTL)-mediated lysis. We here investigate whether the suppressed MHC class I surface expression of ras-transformed fibroblasts is due to dysregulation of the genes of the antigen-processing machinery, the peptide transporters TAP-1 and TAP-2 and the proteasome subunits LMP-2 and LMP-7, and whether it can be restored by gene transfer. In comparison to parental NIH3T3 cells, the ras oncogenic transformants revealed reduced TAP and LMP mRNA expression and impaired function of these genes, leading to deficient peptide transport and peptide loading of MHC class I molecules resulting in instable expression of the MHC class I complex on the cell surface. Enhanced H-2 surface expression due to stabilization of the MHC class I complex could be achieved by culturing ras transformants at low, unphysiological temperature (26 degrees C) or by loading these cells with either exogenous human beta2-microglobulin or MHC class I-binding peptide alone or in combination. Furthermore, interferon-gamma treatment was capable to enhance the expression of TAP, LMP and MHC class I molecules in both parental as well as ras-transformed fibroblasts. Stable transfection of the human TAP-1 cDNA into ras transformants caused a partial reconstitution of the peptide transport and an enhancement of the MHC class I surface expression, whereas the level of MHC class I biosynthesis was not affected by TAP-1 overexpression in parental cells. Together these results point to the existence of an association between oncogenic transformation and deficiencies in the MHC class I antigen-restricted immunosurveillance, suggesting intervention strategies involving specific MHC class I-binding peptides or transfection of the LMP and/or TAP genes to overcome the expression of the immune escape phenotype.

Monoclonal antibody U36, a suitable candidate for clinical immunotherapy of squamous-cell carcinoma, recognizes a CD44 isoform.

At present, tumor-targeting with monoclonal antibodies (MAbs) is among the most promising novel adjuvant-therapy modalities for the treatment of patients with minimal residual disease of head-and-neck squamous-cell carcinoma (HNSCC). For this purpose we developed MAb U36, recognizing a 200-kDa antigen expressed on the outer cell surface of squamous-cell carcinomas and their normal counterparts. Clinical radioimmunoscintigraphy (RIS) and biodistribution studies have shown that the MAb-U36-defined antigen is a suitable target molecule for antibody-based therapy of head-and-neck cancer. In the present study we further characterized the antigen by cDNA cloning. The cDNA was isolated by expression cloning in COS-7 cells. Sequence analysis and database searching revealed that the MAb-U36-defined antigen is identical to the squamous-cell-specific CD44 splice variant epican. The epitope recognized by MAb U36 was mapped by screening overlapping synthetic peptides of the epican-specific region encoded by exon 7-11 (v3-v7), and appeared to be located in the v6 domain. The applicability of MAb U36 for targeting human tumors of various origin expressing the CD44v6 domain is discussed.

Monoclonal antibody U36, a suitable candidate for clinical immunotherapy of squamous‐cell carcinoma, recognizes a CD44 isoform

At present, tumor-targeting with monoclonal antibodies (MAbs) is among the most promising novel adjuvant-therapy modalities for the treatment of patients with minimal residual disease of head-and-neck squamous-cell carcinoma (HNSCC). For this purpose we developed MAb U36, recognizing a 200-kDa antigen expressed on the outer cell surface of squamous-cell carcinomas and their normal counterparts. Clinical radioimmunoscintigraphy (RIS) and biodistribution studies have shown that the MAb-U36-defined antigen is a suitable target molecule for antibody-based therapy of head-and-neck cancer. In the present study we further characterized the antigen by cDNA cloning. The cDNA was isolated by expression cloning in COS-7 cells. Sequence analysis and database searching revealed that the MAb-U36-defined antigen is identical to the squamous-cell-specific CD44 splice variant epican. The epitope recognized by MAb U36 was mapped by screening overlapping synthetic peptides of the epican-specific region encoded by exon 7–11 (v3–v7), and appeared to be located in the v6 domain. The applicability of MAb U36 for targeting human tumors of various origin expressing the CD44v6 domain is discussed. © 1996 Wiley-Liss, Inc.

Expression of the FLT4/VEGFR3 receptor tyrosine kinase encoding gene in hepatic tumors

The FLT4/VEGFR3 tyrosine kinase receptor belongs to a class of receptors for growth factors of the vascular endothelial growth factor family and is important for the biology of lymphatic endothelium. It may play an important role in tumor growth. We have looked for the expression of the FLT4 gene in tumors of various origins. FLT4 expression was not found except in some particular type of tumors: mouse hepatic tumors but not cell lines were shown to expressed Flt4 at a high frequency while Flt4 mRNA was absent or weakly expressed in normal liver, suggesting that Flt4 de novo expression in liver nonparenchymal cells participates in tumor development of this tissue.

Quantitation of Angiogenesis in the Chick Chorioallantoic Membrane Model Using Fractal Analysis

Objective quantitation of new vascular growth in angiogenesis assays has been difficult to achieve. The aim of this study was to test the potential applicability of fractal geometry to objectively quantify angiogenesis in the chick chorioallantoic membrane (CAM). To accomplish this, vascular growth in normal (NC) and tumor grafted (TGC) CAM was compared. Samples of human tumors of various origins acquired from biopsy specimens were grafted to CAMs at Days 6–12 of incubation. Images of 6- to 16-day NC and 10- to 17-day TGC were acquired and the box-counting method was used to estimate fractal dimension (Df). Vascular density (ρv) was derived from box counts. For NC,Dfand ρvincreased steadily from Days 6 to 14, peaked, and began to decrease by Day 15. Results from TGC showed thatDfand ρvsurrounding tumor grafts varied from those of NC. Complexity and density indices were calculated as amount of change inDfand ρvbetween TGC and NC of the same age, respectively. Based on these indices, differences in the angiogenic response elicited by various tumors were readily detected. Our results suggest that differences inDfand ρv, in both the temporal and spatial senses, are accurate and repeatable measures of vascular growth and may be useful for objective quantitation of the angiogenic response.

Immunohistochemical assessment of human microsomal epoxide hydrolase in primary and secondary liver neoplasm: a quantitative approach.

1. Epoxide hydrolases form an enzyme family involved in the metabolism of a variety of xenobiotics including cytostatic drugs and carcinogens. Whether human microsomal epoxide hydrolase--one of the main members of the epoxide hydrolase family--is expressed in neoplasia of the liver has been the subject of a controversial discussion. 2. We therefore developed a quantitative immunohistochemical assay and monitored epoxide hydrolase expression in hepatocellular carcinomas (HCC, n = 20), cholangio-cellular carcinomas (CCC, n = 2) and liver metastases (n = 57) of tumours of various origins, and compared the expression intensities and patterns to normal liver tissue. 3. In normal liver tissue microsomal epoxide hydrolase displays expression of the constitutive type with non-zonal staining of all hepatocytes. 4. When using a quantitative immunohistochemical approach statistically significant differences in microsomal epoxide hydrolase expression were observed between normal tissue, hepatocellular carcinoma and liver metastases (mean optical density 2.35, 1.63 and 0.21 respectively, p = 2.9, 6.3 and 18.9). These data indicate differential expression in different types of liver neoplasm. 5. As microsomal epoxide hydrolase is involved in metabolism of different xenobiotics our findings may have implications for tumour progression.

Overexpression of theMET/HGF receptor in ovarian cancer

The MET oncogene encodes the receptor for Hepatocyte Growth Factor/Scatter Factor, a unique growth factor that induces not only proliferation of epithelial cells, but also cell motility and invasiveness. DNA level and expression of the Met/HGF receptor gene were examined with Southern- and Western-blot analyses, respectively, in human ovary, benign ovarian tumors and epithelial ovarian carcinomas. The Met/HGF receptor was detectable in the surface epithelium of normal ovary. The level of expression was unchanged in benign ovarian tumors of various origins. Fourteen out of 67 malignant carcinomas (20%) showed a 3- to 10-fold increase in expression. In 5 additional cases the Met/HGF protein was overexpressed over 50-fold. This represents a total of 28% of cases. Overexpression was not associated with MET gene amplification. Overexpressing tumors belonged to different histotypic variants, but showed a well-differentiated phenotype. Clinically, overexpression was associated with disease at any pathologic stage, but was significantly correlated with premenopausal status of patients. These data suggest that expression of the Met/HGF receptor may add a selective growth advantage to a narrow subset of differentiated ovarian cancers in premenopausal patients.

Expression of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 in undifferentiated nasopharyngeal carcinoma (lymphoepithelioma) and in malignant epithelial tumors

Immunoreactivity for intercellular adhesion molecule-1 (ICAM-1) and for vascular cell adhesion molecule-1 (VCAM-1), two adhesion molecules of the immunoglobulin (Ig) superfamily, was tested and measured on tissue sections from 16 undifferentiated nasopharyngeal carcinomas (U-NPC), 12 keratinizing squamous cell carcinomas (SCCs) of the head and neck region, and 54 malignant epithelial tumors of various origin. Neoplastic cells of all cases of U-NPC were diffusely and intensely stained for ICAM-1 and VCAM-1. Moreover, ICAM-1 messenger RNA (mRNA) and VCAM-1 mRNA were detected by Northern blot analysis of RNA extracts from two tumors. In the other epithelial tumors focal or diffuse staining for ICAM-1 was observed in 40 cases (66%), whereas reactivity for VCAM-1 was detected in a single case of metastatic undifferentiated carcinoma of unknown origin. The biopsy specimens of U-NPC showed variable infiltration by leukocytes, which were positive for the intergrins lymphocyte function antigen-1 (LFA-1) and alpha-4/beta-1, the corresponding ligands for ICAM-1 and VCAM-1. The possibility that ICAM-1 and VCAM-1 on neoplastic cells may favor the intratumoral recruitment of leukocytes in a way similar to that occurring in crypt epithelium of the palatine tonsil is discussed.

Induction and down-regulation of PLK, a humanserine/threonine kinase expressed in proliferating cells andtumors.

We have identified the nucleotide sequence of the cDNA encoding the human counterpart of the mouse gene Plk (polo-like kinase). The sequence of the human gene, PLK, predicts a serine/threonine kinase of 603 aa. Expression of PLK mRNA appeared to be strongly correlated with the mitotic activity of cells. Resting peripheral lymphocytes did not express the gene at all. When primary T cells were activated by phytohemagglutinin, a high level of PLK transcripts resulted within 2-3 days. In some cases, addition of interleukin 2 to these cells increased the expression of PLK mRNA further. In contrast, primary cultures of human peripheral macrophages, which were not dividing under the culture conditions applied, showed very little or no PLK mRNA. Stimulation of these cells by bacterial lipopolysaccharide, an inducer of several cytokines in macrophages, totally abrogated the expression of PLK mRNA. In line with a function of PLK mRNA expression in mitotically active cells is our finding that six immortalized cell lines examined expressed the gene. In A-431 epidermoid carcinoma cells this expression was down-regulated by serum starvation and enhanced after serum was added again. Tumors of various origin (lung, colon, stomach, smooth muscle, and esophagus as well as non-Hodgkin lymphomas) expressed high levels of PLK transcripts in about 80% of the samples studied, whereas PLK mRNA was absent in surrounding tissue, except for colon. The only normal tissues where PLK mRNA expression was observed were colon and placenta, both known to be mitotically active. No PLK transcripts were found in normal adult lung, brain, heart, liver, kidney, skeletal muscle, and pancreas. In Northern blot experiments with RNA from lymphocytes which were treated with phytohemagglutinin and cycloheximide, PLK transcripts were not detectable, suggesting that PLK is not an early growth-response gene.

Effects of a fibroblast-derived inhibitor on the growth of normal marrow and leukemic clonogenic cells

Blood cells develop in the bone marrow, controlled by a network of regulatory factors, some of which originate in the stroma. Previously, we found that most fibroblastoid (FB) cells growing in primary cultures of rat marrow bear surface antigens different from those found on FB of certain other tissues. As determined by two monoclonal antibodies (“ST3” and “ST4”), the “marrow type” is ST3 +/ST4 − and releases predominantly a colony-stimulating activity (CSA) into its culture media (CM), whereas the “peripheral type” (e.g. lung) is predominantly ST3 −/ST4 + and produces inhibitory activity in excess of CSA. The studies described here show that this inhibitor also is active on rat leukemic myeloblasts (the BNML cell line), but not on eight other cell lines derived from rat tumors of various origins or on the human-derived leukemic cell lines tested. It was produced without exogenous stimulation, was labile to heat and acid, was not neutralized by antisera to transforming growth factor-beta, beta-interferon, or ferritin, and had an apparent mol wt in the range of 100–120 kD (peak of activity by gel filtration). From the results obtained at this time, we are not able to ascribe this fibroblast-derived activity to any known inhibitor molecule.

S‐100 Protein in Ovarian Tumors

The distribution of S 100 protein in 135 ovarian tumors, of which 127 were epithelial, was investigated using the im‐munoperoxidase method. S 100 protein has been demonstrated previously in tumors of various origins. The present study further revealed its characteristic distribution in common epithelial tumors of the ovary. S 100 protein was present in 69% of serous tumors (benign, 50%; borderline, 100%; malignant, 71%), as well as in the serous elements of serous & mucinous mixed tumors (30%). S 100 protein was also demonstrated in 25% of clear cell carcinomas and 29% of endometrioid carcinomas. Interestingly, none of the mucinous tumors were positive for S 100 protein. In addition, the expression of S‐100 protein by epithelial ovarian tumors was compared with that of CA 125 and carcinoembryonic antigen (CEA). The distribution of S 100 protein was similar to that of CA 125, since both antigens were frequently present in serous tumors, although their expression patterns were different. On the other hand, S 100 protein positive cases were almost negative for CEA or vice versa. Our observations indicate that demonstration of S 100 protein in common epithelial tumors of the ovary and comparison of S‐100 protein distribution with that of CA 125 and CEA may further clarify the characteristics of common epithelial tumors of the ovary.

S-100 protein in ovarian tumors : a comparative immunohistochemical study of 135 cases

The distribution of S-100 protein in 135 ovarian tumors, of which 127 were epithelial, was investigated using the immunoperoxidase method. S-100 protein has been demonstrated previously in tumors of various origins. The present study further revealed its characteristic distribution in common epithelial tumors of the ovary. S-100 protein was present in 69% of serous tumors (benign, 50%; borderline, 100%; malignant, 71%), as well as in the serous elements of serous & mucinous mixed tumors (30%). S-100 protein was also demonstrated in 25% of clear cell carcinomas and 29% of endometrioid carcinomas. Interestingly, none of the mucinous tumors were positive for S-100 protein. In addition, the expression of S-100 protein by epithelial ovarian tumors was compared with that of CA 125 and carcinoembryonic antigen (CEA). The distribution of S-100 protein was similar to that of CA 125, since both antigens were frequently present in serous tumors, although their expression patterns were different. On the other hand, S-100 protein-positive cases were almost negative for CEA or vice versa. Our observations indicate that demonstration of S-100 protein in common epithelial tumors of the ovary and comparison of S-100 protein distribution with that of CA 125 and CEA may further clarify the characteristics of common epithelial tumors of the ovary.

Morphologic diversity of long bone adamantinoma. The concept of differentiated (regressing) adamantinoma and its relationship to osteofibrous dysplasia.

A review of the clinical, radiologic, and histologic features of 25 cases of long bone adamantinoma is presented. To answer some questions concerning the nature of these tumors, relevant tissue markers were analyzed in seven cases using immunohistochemical assays. This study confirmed the epithelial nature of long bone adamantinomas irrespective of their wide-ranging morphologic patterns that can mimic tumors of various origin. On the basis of distinct radiologic, histologic, and immunohistochemical patterns, a new type of adamantinoma termed "differentiated adamantinoma" could be distinguished from the classic long bone adamantinomas. The diagnostic features characteristic of the differentiated adamantinoma include: patient age (first two decades), intracortical location of the entire lesion, uniform predominance of an osteofibrous dysplasia-like pattern, and scattered positivity of epithelial elements for cytokeratin. We postulate that the predominance of an osteofibrous dysplasia-like pattern in differentiated adamantinoma is the result of a secondary reparative process overgrowing matured and regressing tumor tissue. It is possible that this process may lead to the total elimination of recognizable tumor cells from the lesion. Therefore, osteofibrous dysplasia (ossifying fibroma) of long bones, which has a similar anatomic location, age distribution, and radiologic appearance as differentiated adamantinoma, may, in some cases, represent the evolution of an underlying adamantinoma. Our analysis suggests that long bone adamantinoma could be another member of the unique family of tumors that may regress spontaneously.

Localization of human malignant tumors with radioiodinated recombinant tissue plasminogen activator : Karonen S-L, Aronen H, Liewendahl K, Nikkinen P, Mantyla M, Lindgren J. Division of Nuclear Medicine, Department of Clinical Chemistry, Helsinki University Hospital, 00290 Helsinki. J Nucl Med 1988;29:1194-9

Human recombinant tissue plasminogen activator (tPA), labeled with 131I(1.1 to 6.2 mCi) by the iodogen method, was administered intravenously to 15 patients with various soft-tissue malignant tumors after blocking of thyroidal radioiodine uptake. Gamma camera imaging was performed 4 and 24 hr after injection; three patients were also imaged 5 days following injection. We observed accumulation of radioactivity in primary and secondary lesions in 11 patients. In this preliminary study we did not detect any definite association between the magnitude of uptake and type of tumor. Tumors were usually visualized already after 4 hr but the uptake was more intense at 24 hr. The target-to-nontarget ratios at 24 hr, determined by computer analysis of stored images, varied from less than 1.2 to 2.1. This is the first demonstration of accumulation of radiolabeled tPA in malignant tissue. We do not know the mechanism of the uptake but because tPA is known to be avidly bound to fibrin, a component of the stroma of many malignant tumors, it is possible that [131I]tPA is bound to fibrin rather than taken up by the malignant cell; various possible cell uptake mechanisms are discussed. Due to the relatively early maximal uptake of this radiopharmaceutical it will be possible to substitute 123I for 131I, a possibility suggesting a potential clinical use of radioiodinated tPA for the detection of malignant tumors of various origin.

Epidermal growth factor receptors in cancer tissues of esophagus, lung, pancreas, colorectum, breast and stomach.

The levels of epidermal growth factor (EGF) receptors were investigated in surgically resected tumors of various origins including esophagus (n = 33), lung (n = 14), pancreas (n = 9), colorectum (n = 10), breast (n = 23) and stomach (n = 8). The 125I‐EGF binding capacities of squamous cell carcinomas of esophagus and lung were exceptionally higher than those of the other cancer tissues. Immunohistochemical staining with an anti‐EGF receptor monoclonal antibody detected EGF receptors in the basal cells and parabasal cells of normal esophageal epithelium and in all the cancer cells of squamous cell carcinoma tissues of esophagus and lung. DNA replicating cells were examined by the bromodeoxyuridine staining method and it was found that the basal cells and parabasal cells of normal epithelium and peripheral cells of cancer pearls are proliferating. Contrary to this, a tumor antigen TA‐4, known as a specific marker for squamous carcinoma, was detected in the differentiated cancer cells and in middle‐layer squamous cells. These results strongly suggest that the increase in EGF receptor levels may be associated with the development of human squamous cell cancers of esophagus and lung. Thus, measurement of EGF receptor expression in tumor tissues has diagnostic value and should prove useful for the development of new therapies.