Loss of heterozygosity on the short arm of chromosome 17 is associated with high proliferative capacity and DNA aneuploidy in primary human breast cancer

Loss of heterozygosity (LOH) on the short arm of chromosome 17 (17p) was found in 27 of 52 (52%) previously untreated primary breast cancers. There was a significant correlation between this 17p allelic loss and two parameters associated with aggressive tumor behavior: high cellular proliferative fraction and DNA aneuploidy. These correlations with high cellular proliferative fraction and DNA aneuploidy were not found in tumors with LOH at nine other chromosome locations. The p53 gene, a putative tumor suppressor gene located at 17p13, was examined for aberrations to determine whether it is the target for the 17p LOH in breast cancer. Unlike other types of human cancer, there were no homozygous deletions or rearrangements of the p53 gene, and only 2 of 13 (15%) were mutated in the conserved region where mutational "hot spots" have been previously located. Therefore, we hypothesize that, in breast cancer, either loss or inactivation of gene(s) on chromosome 17p other than the p53 gene or a different mechanism of p53 gene inactivation may be responsible for the observed high labeling index and DNA aneuploidy associated with LOH at 17p.

A relationship between proteinuria and acute tubulointerstitial disease in rats with experimental nephrotic syndrome

The relationship between tubulointerstitial nephritis and proteinuria was characterized in experimental nephrosis in rats. In one group, proteinuria induced by aminonucleoside of puromycin (PAN) was reduced by using an 8% protein diet and adding the angiotensin I-converting enzyme (ACE) inhibitor enalapril to the drinking water. Two control groups were injected with saline and PAN, respectively, and fed a 27% protein diet. The first group had significantly reduced albuminuria and a definite attenuation of tubular cell injury. There was a strong positive correlation between the number of interstitial macrophages and albuminuria. The beneficial effect was reproduced by dietary-protein restriction alone, whereas ACE inhibition alone had an insignificant effect on the degree of proteinuria. Depletion of circulating T lymphocytes in one group of nephrotic rats eliminated interstitial lymphocytes but did not affect interstitial macrophage influx. Inhibition of the in situ proliferation of resident interstitial macrophages by unilateral kidney irradiation failed to change the intensity of the macrophage infiltration. Treatment of rats with sodium maleate produced proximal tubular cell toxicity but interstitial inflammation did not develop, suggesting that the latter is not a nonspecific response to tubular injury. These studies demonstrate a strong relationship between tubulointerstitial nephritis and the severity of proteinuria in experimental nephrosis.

Early and late events in the development of human breast cancer

We hypothesize that early events in the development of at least some human breast cancers involve faulty epithelial-mesenchymal interactions and that the stromal cells themselves play an active role in this abnormal process. In contrast, later events accelerating breast tumor progression may occur in association with genetic changes involving only the malignant epithelial cells. These conclusions arise from a review of the literature, our comparative studies of HA metabolism in fibroblasts cultured from either normal or malignant breast tissues, and from molecular-genetic studies performed on sequential specimens from a single patient and on a wide variety of human breast tumor samples. HA is a proteoglycan component of the ECM which is known to stimulate epithelial cell detachment and motility and is most abundant in fetal and rapidly growing tissues. We find that many breast cancer-derived fibroblasts are stimulated to produce HA in response to TGF-beta under conditions where HA accumulation by normal tissue fibroblasts is almost uniformly inhibited. In a single patient, we had the opportunity to examine three malignant effusions that occurred sequentially to identify genetic changes associated with the later stages of breast cancer progression. Although, common cytogenetic abnormalities were found in all the effusion samples, only the last effusion exhibited a loss of heterozygosity at the c-Ha-ras locus. In this case, the allelic loss correlated with improved growth in vitro of the primary cells and with ability to become a permanently established cell line.(ABSTRACT TRUNCATED AT 250 WORDS)

Overexpression of matrix Gla protein mRNA in malignant human breast cells: isolation by differential cDNA hybridization

Genetic alterations are involved in the development of human breast cancer. We sought to isolate genes that are differentially expressed or suppressed in cultured human breast carcinoma cells as compared to cultured normal human breast epithelial cells by employing differential screening of selected cDNA libraries. Analysis of several clones thus isolated revealed that the matrix Gla protein (MGP) gene is overexpressed in the breast cancer cell line 600 PEI, though is transcribed at lower levels in most other mammary derived cultures. MGP requires vitamin K dependent gamma-carboxylation for its known function and thus can be inhibited by vitamin K antagonists. This raises the possibility that MGP may be among those factors that when inhibited by vitamin K antagonists reduce metastases in experimental models. Among the gene whose transcription is consistently suppressed upon mammary transformation were fibronectin and the type I keratin, K14. Differential cDNA screening therefore is an effective method of identifying genes involved in various aspects of mammary cell transformation.

Polymerase chain reaction based assay to detect allelic loss in human DNA: loss of beta-interferon gene in chronic myelogenous leukemia

We have developed a polymerase chain reaction (PCR) based technique to detect allelic loss. In this differential PCR a target gene and a reference gene are coamplified in the same reaction vessel. The ratio of the intensity of the two resultant bands is an indication of relative gene dosage. This procedure is sensitive in that gene copy ratios of 2:1 and 3:2 (reference: target gene) can readily be detected. Using this differential PCR, we have examined 64 cases of chronic myelogenous leukemia (CML) for the loss of the beta 1-interferon gene, a relatively common event in certain human leukemias and lymphomas. Only one patient who was Philadelphia chromosome positive and who was in blast crisis exhibited allelic loss of the beta-interferon gene. Thus despite deletions at the beta-interferon locus in the CML cell line, K562, this perturbation is rarely seen in primary CML samples.

Mutations of the ras protooncogenes in chronic myelogenous leukemia: a high frequency of ras mutations in bcr/abl rearrangement-negative chronic myelogenous leukemia

Seventy cases of chronic myelogenous leukemia (CML) were analyzed for the presence of ras mutations using polymerase chain reaction (PCR), oligonucleotide hybridization, and direct PCR sequencing. All cases had preceding cytogenetic and bcr rearrangement studies. Aberrant ras genes were detected in none of 39 patients with Philadelphia (Ph) chromosome or bcr/abl rearrangement positive chronic-phase CML and in only 1 of 18 patients in blast crisis, suggesting that ras mutations have little or no role in initiation or progression of common CML. Seven of 13, or 54% of patients with bcr/abl rearrangement negative chronic phase CML (atypical CML) harbored mutations in ras, however. This high incidence of ras mutations, together with the absence of bcr/abl rearrangement, provides evidence that atypical CML is an entity that is molecularly distinct from common CML. Moreover, the clinical characteristics and the high frequency of ras mutations suggest that atypical CML may constitute a subset of the myelodysplastic syndrome and may be best classified as a variant of chronic myelomonocytic leukemia (CMML).

Bifunctional oligonucleotide probes synthesized using a novel CPG support are able to detect single base pair mutations

A novel multifunctional controlled pore glass, MF-CPG (Fig. 1), has been synthesized and used to incorporate 3' terminal primary aliphatic amines into synthetic oligonucleotides. MF-CPG consists of a unique succinic acid linking arm which possesses both a masked primary amine for label attachment and a dimethoxytrityl protected hydroxyl for nucleotide chain elongation. Using MF-CPG, we have devised a simple and convenient technique to attach non-radioactive labels to the 3' terminus of oligonucleotides. Bifunctional probes can then be constructed by 32P labeling the 5' terminus with T4 kinase and gamma 32P-ATP. Using such bifunctional oligonucleotide probes in conjunction with polymerase chain reaction (PCR) amplification, we were able to detect single base substitutions in a target segment of the human H-ras protooncogene employing either functionality. Our technique thus expands the potential applications for oligonucleotides as hybridization probes.

Detection of amplified oncogenes by differential polymerase chain reaction

Oncogene amplification has been found in a variety of human cancers and may have prognostic importance. Therefore, techniques which facilitate detection of gene amplification could have wide applicability. We have devised a sensitive, rapid, and non-radioactive procedure for detecting alterations in gene copy number based on the polymerase chain reaction (PCR). In this technique, called differential PCR, a target gene and a single-copy reference gene are co-amplified by PCR in the same reaction vessel. The level of target gene amplification is reflected in the ratio between the two resulting PCR-product bands. We show that this method can detect as low as two-fold amplification of specific target genes. Furthermore, amplification of neu and the epidermal growth factor receptor gene could be detected in as few as 100 breast carcinoma cells or in single sections of formalin-fixed, embedded material.

Effects of c-myc overexpression on the growth characteristics of MCF-7 human breast cancer cells

Amplification and overexpression of the c-myc protooncogene have been observed in 22 to 32% of primary human breast cancers, yet the exact role of this gene in mammary tumor progression is unclear. We sought to elucidate this role by overexpressing cloned myc genes in the human breast carcinoma cell line MCF-7. We found that augmented myc RNA levels were associated with slower in vitro growth rates, but that estrogen receptor levels, the requirement for estrogen for in vivo growth in castrated athymic nude mice, and sensitivity to the antiestrogen, tamoxifen were not altered. Furthermore, chemosensitivity to the cytotoxic agent, Adriamycin, was not affected. Lastly, overexpression of a transfected myc gene did not suppress endogenous myc levels unlike the findings in lymphoma cells. Thus our data suggest that the effect of augmented myc expression in human breast cancer cells is complex and may not induce more malignant patterns of growth as has been suggested for other human cancers.

Incidence of activating ras oncogene mutations associated with primary and metastatic human breast cancer

To test the hypothesis that ras activation is involved in the final stages of breast cancer progression, we analyzed tumor DNA derived from 60 different patients and extracted from 40 invasive primary breast tumors, seven lymph node and skin metastases, nine metastatic effusions, and five established breast cancer cell lines. The polymerase chain reaction technique was used to amplify DNA fragments containing Kirsten-(Ki-), Harvey-(Ha-), and N-ras codons 12, 13, and 61 which were then probed on slot-blots with labeled synthetic oligomers to detect nonconservative single base mutations. Activating mutations were found in one of 40 primary tumors (Ki-ras codon 13), zero of seven lymph node and skin metastases, one of nine metastatic effusions (Ki-ras codon 12), and two of five cell lines (Ki-ras codons 12 and 13). These results indicate that activating ras mutations are rarely involved in either the initiation or metastatic progression of human breast cancer.

Molecular lesions involved in the progression of a human breast cancer

Specific genetic alterations are observed in human breast cancer, but little is known about when these occur in the evolution of the disease. Three breast cancer effusions that occurred sequentially in a single patient were examined. Common cytogenic abnormalities were found in all effusion samples suggesting a single progenitor metastatic cell. Only the last effusion, however, exhibited a mutation of the c-K-ras gene and a loss of heterozygosity at the c-H-ras locus. These specific genetic abnormalities detected in the last effusion was correlated with improved in vitro growth of the primary cells, and with the ability to establish breast cancer cell lines. Thus a mutant ras gene and the loss of heterozygosity at the c-H-ras locus were associated with a more aggressive tumor phenotype occurring late in the course of this patient's disease and not with the initiation of the primary breast cancer, or in the establishment of metastases.

Estrogen-induced post-transcriptional modulation of c-myc proto-oncogene expression in human breast cancer cells

The effects of estradiol (E2) on c-myc proto-oncogene expression were studied in the estrogen receptor (ER)-positive human breast cancer cell line, MCF-7. A biphasic modulation in c-myc mRNA levels occurs during the first 24 h of E2 (1 nM) exposure and in the absence of changes in MCF-7 culture growth, with transcript levels rising 4-6-fold within 1 h, returning to near base-line level after 3-6 h, and increasing again after 24 h of exposure. In contrast, the growth-inhibiting antiestrogen, tamoxifen (1 microM), reduces c-myc to 20% of the pretreatment level within 3-6 h of exposure, and this early decline is followed by a gradual return toward base-line level after continuous 72-h treatment. In ER-negative cells there is no change in c-myc expression following E2 exposure. MCF-7 nuclear runon assays show that c-myc transcription rates remain unchanged from base line for 24 h after E2 administration; as well, cycloheximide inhibition of protein synthesis superinduces c-myc expression and prevents E2 modulation of transcript levels. These results indicate that post-transcriptional modulation of c-myc by E2 is mediated by a labile degradative protein or otherwise dependent on active protein synthesis. We also developed MCF/nm and MCF/dm sublines by transfecting normal cells with human c-myc exons 2-3, transcriptionally driven by a retroviral long terminal repeat. Expression of the transfected c-myc genes in these sublines remains constant and elevated 10-fold, while transcript levels from the endogenous proto-oncogene continue to be modulated by E2. These findings suggest that in ER-positive breast cancer cells, E2 can modulate c-myc mRNA levels by a post-transcriptional mechanism that depends on gene sequences upstream from c-myc exon 2.

Percutaneous nephrostomy in conjunction with ESWL in treatment of nephrolithiasis

The use of percutaneous nephrostomies (PCNs) in 1456 patients (1660 kidneys) treated with extracorporeal shock-wave lithotripsy (ESWL) was evaluated. In this group, 138 PCNs (130 patients) were performed in 133 kidneys. Forty-seven percent of PCNs were placed in patients with staghorn calculi; 24% were for stones in the renal pelvis, and 20% for ureteral stones. The most common indication for PCN was fever and obstruction (57%). In 15%, the indications were failure to decompress an obstructed system from a retrograde direction, clogged double-J ureteral stents, and perforation of the ureter. Prophylactic PCN placement in the treatment of staghorn calculi and large stones in the renal pelvis accounted for 12%. Five percent were placed for miscellaneous other reasons, and for 11% there was no documentation of the indication because they were placed before the patients came to our center. Localization of the collecting system for optimal placement of PCN is unique in ESWL patients because the residual stone fragments provide natural contrast. This eliminates the need for administration of contrast material in 50% of the patients. Twenty-six percent of PCN tracts were subsequently used for other procedures (e.g., percutaneous nephrolithotomy, fragment irrigation, ureteral stone manipulation). Bleeding complications from PCN occurred in 7%. Other minor complications occurred in 12% of cases. PCN is a useful adjuvant to ESWL treatment of kidney stones. Although its major use is to relieve urinary tract obstruction, it is also used as a preliminary step in planning other percutaneous interventional procedures. This is particularly the case in the treatment of large bulky stones in the renal pelvis and staghorn calculi.

Immunoneutralization of somatostatin and neurotensin: effect on gastric acid secretion

Cell lines producing monoclonal antibodies to somatostatin and neurotensin, designated S-10 and NT-C5, respectively, have recently been generated. The purpose of the present immunoneutralization study in urethan-anesthetized gastric fistula rats is 1) to examine the ability of these antibodies to block the inhibitory effect of their target peptides on meal-stimulated gastric acid secretion and 2) to use these antibodies as probes to determine whether somatostatin and/or neurotensin are involved in the inhibition of gastric acid secretion produced by intraduodenal, intra-ileal, and intracolonic fat infusions. The results demonstrate that both S-10 and NT-C5 successfully bound exogenous somatostatin and neurotensin in vivo. S-10 but not NT-C5 prevented the inhibition of gastric acid secretion produced by intraduodenal fat. NT-C5 but not S-10 prevented the inhibition of gastric acid secretion produced by intra-ileal fat. Neither S-10 nor NT-C5 prevented the inhibition of gastric acid secretion produced by intracolonic fat. We conclude that somatostatin is associated with proximal and neurotensin with distal small bowel intestinal fat-induced inhibition of gastric acid secretion.

Oncogene v-src transforms and establishes embryonic rodent fibroblasts but not diploid human fibroblasts

The conversion of cells from a normal phenotype to full malignancy apparently requires multiple genetic events. Efforts to reconstruct multistep tumorigenesis in cell culture have shown that two types of oncogenes (typified by HRAS and MYC) can cooperate to elicit complete transformation. Transformation of embryonic rodent cells by single oncogenes is reputed either not to occur or to require specialized circumstances. It has not been known how the large group of oncogenes that encode protein-tyrosine kinases might fit into this scheme. We now report that v-src, a prototype for the kinase oncogenes, can convert rat embryo fibroblasts to a fully transformed and tumorigenic phenotype when the gene is expressed vigorously. By contrast, v-src had no demonstrable effect on diploid human fibroblasts. Our results sustain the view that it is possible for at least some oncogenes to achieve a potency sufficient for unilateral tumorigenesis.

Transforming genes in chronic myelogenous leukemia

Chronic myelogenous leukemia (CML) is a hematopoietic malignancy characterized by an indolent chronic phase that invariably leads to a "blast crisis" indistinguishable from acute leukemia. Using a sensitive assay based on gene transfer and tumorigenesis, we sought evidence that damage to protooncogenes might figure in the progression from the chronic to the blast phase of CML. Seven of the 12 patients with CML examined in this manner harbored transforming genes. Mutations in RAS protooncogenes were detected in the leukemic cells from 1 of 6 chronic-phase patients, and 3 of 6 blast-crisis patients. In addition, a presently unidentified transforming gene (neither RAS nor RAF) was detected in 1 patient with chronic phase and 1 with blast crisis. Our data indicate that mutations in RAS genes may play diverse roles in the pathogenesis of CML.

The enhanced transfer of drug-resistant genes in NIH-3T3 cells transformed by the EJras oncogene

The spontaneous transfer of drug resistance genes has been shown to take place between cultured mammalian NIH-3T3 cells and occurs with a hierarchy of transfer efficiencies, transformed cells being more efficient than non-transformed cells. This experiment was accomplished by co-cultivating two NIH-3T3 sublines, each transfected by standard plasmid methods with a different drug resistance gene, subjecting the mixed population to double selection by adding both drugs to the mixed cell culture, and isolating single cells which were resistant to both drugs. The genes used were the neo gene and gpt gene which conferred resistance to the drugs G418 and mycophenolic acid, respectively. DNA analysis confirmed the presence of both resistance genes in the cells which were resistant to both drugs. The mechanism of this gene transfer was by cell fusion rather than by chromosomal DNA uptake. The efficiency of gene transfer, as indicated by the number of double-resistant colonies standardized by number of cells cultured, was much higher between two sublines of cells transformed by the EJras oncogene than between one transformed and one non-transformed subline, which in turn was higher than between two non-transformed sublines. The higher efficiency of gene transfer between the transformed cells also occurred when these cells were injected into nude mice, thus demonstrating that the same process occurred in vivo. It would appear that drug resistance genes may be transferred spontaneously in cultured mammalian cells by cell fusion, and that transformed cells have a higher efficiency of gene transfer compared to non-transformed cells.

Mutations of the Kirsten-ras proto-oncogene in human preleukaemia

The myelodysplastic syndrome (MDS) or preleukaemia is a haematological disorder characterized by low blood counts, bone marrow cells of abnormal appearance and progression to acute leukaemia in as many as 30% of patients. The distinctive preleukaemic and leukaemic phases of this disease make it an attractive model for neoplastic progression in human tumours. We reasoned that, because dominantly transforming genes (such as mutant alleles of ras proto-oncogenes) are found so frequently in acute leukaemia, the search for these genetic lesions during the clinical course of patients with MDS might give us insight into the function of oncogenes in leukaemogenesis. We report here that bone marrow cells from two of four patients with preleukaemia, and from one patient who progressed to acute leukaemia from MDS, contained a transforming allele of the Ki-ras proto-oncogene. In one preleukaemic patient, a novel mutation in codon 13 of this ras gene was detected in bone marrow cells harvested 1.5 years before the acute leukaemia developed. Our findings provide evidence that ras mutations may be involved in the early stages of human leukaemia.

Inhibition of protein synthesis by monoclonal anti-idiotypic antibody-ricin A chain conjugates in MOPC 315 myeloma cells

Three monoclonal antiidiotypic antibodies (AIA) to MOPC 315 IgA, G3 (IgG2b), A2 (IgG1) and D10 (a hybrid molecule consisting of gamma 1 and gamma 2a heavy chains), were characterized with respect to their binding constants (Ka) to MOPC 315 mouse myeloma cells. The Ka of G3 and A2 was 10(8)/mole; and that of D10 was 3 X 10(7)/mole. The AIA did not bind to a non-immunoglobulin (Ig) producing subclone of MOPC 315 cells (MOPC 315.36). Immunotoxins derived by conjugating ricin A chain (RTA) to G3 and A2 but not to D10 preferentially inhibited protein synthesis in MOPC 315 over MOPC 315.36 cells. These results suggest that the effectiveness of these immunotoxins assessed on the basis of their targeted cytotoxicity against MOPC 315 cells was dependent on the Ka but not on the Ig subclass of the AIA component of the immunotoxin.

Treatment of nasopharyngeal carcinoma with human leukocyte interferon

Nasopharyngeal carcinoma (NPC) is a human neoplasm closely associated with Epstein-Barr virus (EBV). Human leukocyte interferon (IFN) has known antiviral and antineoplastic properties. After initial IFN treatment in one NPC patient demonstrated acceptably low toxicity, 12 additional patients were treated on a protocol with IFN, 10 X 10(6) units intramuscularly (IM) daily for 30 days. IFN did not affect serum anti-EBV antibody titers (IgA and IgG antiviral capsid and early antigens). Of six patients tested, none was found to excrete EBV in saliva before, during, or after IFN. Four patients had measurable tumor regression (two partial responses and two minor responses), three had stable disease, and five patients plus the initial preprotocol patient had progressive disease. Toxicity included fever, fatigue, and myalgias in all patients, thrombocytopenia in two patients, and neutropenia in three patients. Three patients were withdrawn from the study, one each for severe fatigue, neutropenia, and hypotension. This study demonstrates that IFN has sufficient activity in advanced NPC to justify further investigation.

A radioimmunoassay for total captopril in human serum or plasma samples

A radioimmunoassay for the measurement of total captopril in serum and heparinized plasma has been developed. Prior to the assay, serum or heparinized plasma samples are subjected to tri-n-butyl-phosphine reduction followed by N-ethylmaleimide (NEM) derivatization. The assay utilizes in-house NEM-captopril antibody, [125I]NEM-captopril radiolabel and human serum standards. Satisfactory zero binding and sensitivity are obtained after 3 h of incubation at room temperature. Separation of the antibody-bound and free radiolabeled antigen is achieved by employing a polyethylene glycol solution. The assay was shown to have excellent parallelism, recovery, and precision. Cross-reactivities with potentially interfering substances were low.