An updated and validated model for predicting the performance of a biological control agent for the oriental migratory locust

BACKGROUND

The oriental migratory locust is a major crop pest across eastern and south-eastern Asia. Metarhizium anisopliae is an effective biopesticide agent used for locust control, but its performance is temperature dependent, and thus can be more variable than chemical pesticide performance. To predict biopesticide performance for the control of the oriental migratory locust, we adapted a previous temperature-dependent model and validated it using field trial data. To increase the applicability of this model, we explored the use of readily available temperature variables, as well as our own satellite-derived canopy temperature variable, to run the model.

RESULTS

Compared to collected in situ temperature data, our canopy temperature variable most accurately represented the ambient temperature experienced by the locust. When the biopesticide performance model was run using this canopy temperature and compared to field trials results, the model predictions were more accurate than when the model was run with the other temperature variables. The accuracy of the biopesticide performance model was impacted by vegetation cover, but across the areas most associated with locust oviposition, growth and migration, the model predictions were satisfactorily accurate to guide biopesticide operational use.

CONCLUSION

We validated the model in six provinces in China, representing the three agro-ecological zones largely representative of the oriental migratory locust problem areas in China, Thailand, Cambodia and Vietnam. Whilst further validation work is needed, this model could be used in these countries to assess, at a fine spatial scale, the appropriateness of M. anisopliae for controlling the oriental migratory locust. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Influence of oestradiol and tamoxifen on oestrogen receptors-alpha and -beta protein degradation and non-genomic signalling pathways in uterine and breast carcinoma cells

Tamoxifen acts as an oestrogen antagonist in the breast reducing cell proliferation, but in the uterus as an oestrogen agonist resulting in increased cell proliferation. Tamoxifen exerts its tissue-specific effects through the oestrogen receptors (ERalpha or ERbeta). The levels and functions of the two ERs affect the response of the target tissue to oestrogen and tamoxifen. We examined the control of ER stability in breast and uterine cell lines using western blotting and RT-PCR. In MCF-7 breast-derived cells, ERalpha and ERbeta proteins were rapidly degraded via the proteasome pathway in response to oestradiol; conversely tamoxifen stabilised both receptors. In Ishikawa uterine-derived cells, oestradiol and tamoxifen stabilised ERalpha but led to degradation of ERbeta by the proteasome pathway. Further investigations showed that oestradiol induced activation of the non-genomic ERalpha/Akt signalling pathway in MCF-7 cells. We have demonstrated that the alternative Erk signalling pathway is activated in Ishikawa cells following oestradiol treatment in the absence of an active proteasome pathway and therefore increased levels of ERbeta. In conclusion, our data have demonstrated tamoxifen or oestradiol control of ER subtype stability and that non-genomic activation of transcription pathways is cell specific.

Short-term dosing of alpha-hydroxytamoxifen results in DNA damage but does not lead to liver tumours in female Wistar/Han rats

It is now generally accepted that activation of tamoxifen occurs as a result of metabolism to alpha-hydroxytamoxifen. In this study, alpha-hydroxytamoxifen was given to female Wistar/Han rats (0.103 or 0.0103 mmol/kg, intraperitoneally, daily for 5 days). This resulted in liver DNA damage, determined by (32)P-post-labelling, of 3333 +/- 795 or 343 +/- 68 adducts/10(8) nucleotides, respectively (mean +/- SD, n = 4). Following HPLC separation, the retention times of the major alpha-hydroxytamoxifen DNA adducts were similar to those seen following the administration of tamoxifen. However, after rats were treated with alpha-hydroxytamoxifen (0.103 mmol/kg) for 5 days and the animals kept for up to 13 months, no liver tumours developed (0/7 rats), even with phenobarbital promotion (0/5 rats). GST-P foci were detected in the liver, but only after 13 months was their number or area significantly increased over the corresponding controls. When alpha-hydroxytamoxifen was given to female lambda/lacI transgenic rats (0.103 mmol/kg orally for 10 days) and the animals killed 46 days later, there was an approximate 1.8-fold increase in mutation frequency but no significant increase in G:C to T:A transversions as described after tamoxifen treatment. It is concluded that DNA damage alone, resulting from the short-term administration of alpha-hydroxytamoxifen, is not sufficient to initiate liver tumours even with phenobarbital promotion. As with tamoxifen, long-term exposure may be required to allow promotion and progression of transformed cells.

Chemoprevention of breast cancer by tamoxifen: risks and opportunities

The antiestrogen tamoxifen is widely used in the adjuvant therapy of breast cancers in women and helps to prevent the occurrence of breast tumors in healthy women. However, epidemiological studies have shown tamoxifen treatment to be associated with a 2- to 5-fold increased risk of endometrial cancer. In rats but not in mice, long-term administration of tamoxifen results in an increase in hepatocellular carcinomas. Mechanistically, this occurs through metabolic activation of the drug, mainly by the CYP3A family, to an electrophilic species, that causes DNA damage in target tissues, and subsequently leads to gene mutations. It is controversial whether low levels of DNA damage occur in human uterine tissues, and there is no evidence that this can be causally related to the mechanisms of carcinogenesis. In healthy women, the risk:benefits for the use of tamoxifen is in part related to the risk of developing breast cancer. The results from the carcinogenicity studies in rats do not predict the likelihood that women will develop liver cancer or indeed cancers in other organs. The mechanism of endometrial cancer in women remains unresolved, but the experience with tamoxifen has highlighted the potential problems that need to be addressed in the assessment of future generations of selective estrogen receptor modulators.

Association of tamoxifen biliary excretion rate with prior tamoxifen exposure and increased mdr1b expression

ATPase transporter proteins are commonly found in the hepatocyte canalicular membrane. Some of these, in particular the multidrug resistance (mdr1b) gene, have been previously demonstrated to be inducible genes. In this study, we found that tamoxifen induced expression of the mdr1b gene in the liver up to 40-fold after 14 days' exposure to tamoxifen in the diet at a concentration of 420 ppm. As tamoxifen and its metabolites are primarily excreted into the bile, we investigated if the increased expression of mdr1b in the liver following tamoxifen exposure had any effect on its excretion in rats. We found that the excretion of tamoxifen and its metabolites into bile was increased from 8 +/- 1% to 51 +/- 18% (mean +/- SD) of an administered dose of 180 nmol/kg over a collection period of 3 hr in rats that had received tamoxifen (35 mg/kg) orally for 12 days (plus a 3-day rest) prior to the experiment. These data suggest that prolonged treatment with tamoxifen may result in lower serum and tumour concentrations, due to a self-mediated enhancement of excretion via mdr1b gene-encoded P-glycoprotein. This may have implications for other drugs sharing the same route of excretion and co-administered with tamoxifen.

Phase I trial and tumour localisation of the anti-EGFR monoclonal antibody ICR62 in head and neck or lung cancer

The purpose of this study was to determine the effect of the first rat monoclonal antibody (MAb ICR62) to the epidermal growth factor receptor (EGFR) in a phase I clinical trial in patients with unresectable squamous cell carcinomas. This antibody effectively blocks the binding of EGF, transforming growth factor (TGF)-alpha and HB-EGF to the EGFR, inhibits the growth in vitro of tumour cell lines which overexpress the EGFR and eradicates such tumours when grown as xenografts in athymic mice. Eleven patients with squamous cell carcinoma of the head and neck and nine patients with squamous cell carcinoma of the lung, whose tumours expressed EGFR, were recruited. Groups of three patients were treated with 2.5 mg, 10 mg, 20 mg or 40 mg of ICR62 and a further eight patients received 100 mg. All patients were evaluated for toxicity using WHO criteria. Patients' sera were tested for the clearance of MAb ICR62 and the development of human anti-rat antibodies (HARA). No serious (WHO Grade III-IV) toxicity was observed in patients treated with up to 100 mg of antibody ICR62. Antibody ICR62 could be detected at 4 h and 24 h in the sera of patients treated with 40 mg or 100 mg of ICR62. Only 4/20 patients showed HARA responses (one at 20 mg, one at 40 mg and two at 100 mg doses) and of these only the former two were anti-idiotypic responses. In four patients receiving doses of ICR62 at 40 mg or greater, biopsies were obtained from metastatic lesions 24 h later and examined for the localisation of ICR62 using anti-rat antibody reagent. In these patients we showed the localisation of MAb ICR62 to the membranes of tumour cells; this appeared to be more prominent at the higher dose of 100 mg. On the basis of these data we conclude that MAb ICR62 can be administered safely to patients with squamous cell carcinomas and that it can localise efficiently to metastases even at relatively low doses.

Phosphoinositide-dependent in vitro phosphorylation of profilin by protein kinase C. Phospholipid specificity and localization of the phosphorylation site

Phosphoinositides bind to profilin and regulate actin-based cytoskeletal protein assembly. We report here that profilin is phosphorylated in vitro by protein kinase C (PKC) in the presence of phosphoinositides and micromolar concentrations of calcium. PKC-mediated phosphorylation of profilin was observed only in the presence of phosphoinositides; phosphatidylserine and diacylglycerol (known activators of PKC) and other lipids, including phosphatidic acid and phosphatidylglycerol phosphate, did not activate the phosphorylation. The activation of PKC-mediated phosphorylation of profilin by phosphoinositides was as follows: phosphatidylinositol (PI) 4-phosphate (K(m) = 18 microM) > PI 4,5-bisphosphate (K(m) = 30 microM) > PI (no activation). About 0.5 mol phosphate was incorporated per mol of profilin. Phosphorylation of profilin by PKC was not affected by the presence of various concentrations of actin. Phospho-amino acid analysis showed serine to be the only amino acid phosphorylated. The amino acid sequence of a phosphopeptide from CNBr-digested profilin corresponded to the COOH-terminal peptide of profilin (Ala-Ser-His-Leu-Arg-Ser-Gln-Tyr). Further digestion of this phosphopeptide by trypsin generated two phosphopeptides (Arg-Ser-Gln-Tyr and Ser-Gln-Tyr), thereby confirming that the phosphorylation site was the antepenultimate Ser (Ala-Ser-His-Leu-Arg-Arg-Ser(P)-Gln-Tyr).

Perturbation of hepatocyte nuclear populations induced by iron and polychlorinated biphenyls in C57BL/10ScSn mice during carcinogenesis

The induction of hepatocarcinogenesis by polychlorinated biphenyls (PCBs) in C57BL/10ScSn mice is markedly potentiated by iron. To investigate the effects of iron and PCBs on nuclear populations, C57BL/10ScSn mice received a single dose of iron-dextran (600 mg Fe/kg) and were fed a diet containing 0.01% of the PCBs mixture Aroclor 1254 for up to 6 months. DNA content of isolated nuclei and hepatocytes was estimated by flow cytometry. Cell suspensions and nuclei isolated from Aroclor treated mice after 6 months contained increased diploid (2N) populations compared to controls. In contrast, iron treatment of mice markedly enhanced fractions of octoploid (8N) nuclei by 2 weeks and this effect persisted over the 6 month period. When Aroclor 1254 and iron were administered together there was a synergistic increase in the mononucleated diploid fraction which was significant at 2 weeks and highly significant at 6 months. This became the predominant nuclear effect. At six months, Aroclor 1254 and iron, both alone and in combination, also increased the rate of DNA synthesis in hepatocytes as measured by bromodeoxyuridine (BrdU) incorporation. The chronic polyploidizing effect of iron overload alone was investigated further and shown to be proportional to the dose and was detectable as early as 2 days after 600 mg Fe/kg and 1 week after 150 mg Fe/kg. Polyploidization of nuclei was inhibited by the oral iron chelator CP94. Iron also induced a prolonged reduction in the incidence of binucleated cells. Histologically, nuclear enlargement due to iron was confined to the midzonal region of the liver lobule, whereas iron deposition was greatest in the periportal region. Iron (600 mg/kg) also caused increased nuclear polyploid states in hepatocytes of adult rats and gerbils. Similarly, weanling mice with a dominantly diploid cell population, when treated with iron (300 mg/kg), exhibited a significant shift to a tetraploid (4N) population and a marked increase in proliferation as measured by BrdU incorporation and proliferative cell nuclear antigen (PCNA) detection. These results indicate that Aroclor 1254 and iron induce changes in the mouse hepatocyte population that involve 2N and 8N nuclei respectively. The combination treatment leads to the emergence and proliferation of a mononucleated, diploid population as observed frequently in chemical hepato-carcinogenesis. The reason for the chronic polyploidizing effect of iron is unknown, but may imply both increased DNA synthesis and impairment of nuclear division with implications in human conditions of iron overload.

Primary structure of the large subunit of trifunctional beta-oxidation complex from pig heart mitochondria

The amino-terminal and internal sequences of the isolated large subunit of trifunctional beta-oxidation complex from pig heart mitochondria were determined by Edman degradation. The results demonstrated that the sequence of this novel beta-oxidation enzyme is identical with the sequence recently reported for a porcine gastrin binding protein that serves as the gastrin receptor on parietal cell surfaces. Evidence is provided to show that it is unlikely that the porcine gastrin binding protein has such a sequence. The data lead us to conclude that the mature large subunit of porcine trifunctional beta-oxidation complex is composed of 727 amino acid residues with a calculated molecular weight of 79,113, while the precursor of this long-chain fatty acid oxidation enzyme has a mitochondrial presequence consisting of 36 residues and a calculated M(r) of 83,099.

Immunotherapy with antibodies to the EGF receptor

A series of rat monoclonal antibodies (MAbs) has been generated against the extracellular domain of the receptor for EGF which block the binding of EGF and TGF alpha to the receptor and inhibit the growth in vitro of a range of carcinoma cell lines that over-express the receptor for EGF. Some of these antibodies were able also to induce the complete regression of xenografts of EGFR-over-expressing tumours when treatment was started, either at the time of tumour inoculation or later when the tumours were established. The most effective of these antibodies was ICR62, which was also able to activate host immune effector functions. We conclude that antibodies which block growth-factor-ligand interaction can have a profound influence on the proliferative capacity of tumour cells in vivo and may have useful clinical application.

The growth-response of human tumor-cell lines expressing the EGF receptor to treatment with EGF and or mabs that block ligand-binding

We have investigated the effect of treatment with epidermal growth factor (EGF) and/or monoclonal antibodies (Mabs) to the epidermal growth factor receptor (EGFR) on the growth in vitro of a number of human tumour cell lines. Mabs ICR10, ICR11, and ICR16 that prevent the binding of both I-125-EGF and I-125-TGFalpha to the EGF receptor were found to inhibit the growth of human tumour cell lines overexpressing the EGF receptor. At high concentrations (5 nM), EGF was also found. to inhibit the growth of HN5, A431 and MDA MB-468 cells whereas the proliferation of SKBR3 and HN6 cells was stimulated. While some of the cell lines (e.g. HN5 and HN6) were very susceptible to growth inhibition by antibodies to the EGFR others, known to secrete autocrine growth factors (e.g. A431 and MDA MB-468), were less affected by these antibodies. Indeed, growth of the latter cell lines was inhibited more effectively by the addition of 5 nM of exogenous EGF than by treatment with 156 nM of the anti-EGFR Mabs ICR16, ICR11, and ICR10. In addition, we show that the growth of HN5 cells, which express very large numbers of EGF receptors (1.4x10(7)/cell), was stimulated at picomolar concentrations of EGF but inhibited at concentrations of EGF in the nanomolar range. Maximal stimulation (25% above control) was observed with the addition of 78 pM EGF to the cultures. The mitogenic effect of low concentrations of EGF and the growth inhibitory effect of nanomolar concentrations of EGF on HN5 cells could be reversed by the addition of 156 nM of the anti-EGFR antibodies. We conclude that growth inhibition can follow from either inhibition of signal transduction by blocking ligand binding to the EGFR or from excess binding of ligand. With tumours that produce significant quantities of autocrine growth factors the latter will compete with the Mabs for binding to the receptor and reduce their effectiveness.

Radioimmunolocalisation in breast cancer using the gene product of c-erbB2 as the target antigen

Lymph node status is still the single most important prognostic factor in breast cancer. Axillary surgery remains the only reliable means of providing this information. This pilot study evaluates using a highly specific radiolabelled monoclonal antibody to provide equivalent information by a non-invasive technique. After optimisation of labelling conditions, our first antibody, ICR12 (against the gene product of c-erbB-2) was evaluated in a mouse model system. Twenty-four hours post i.v. injection the mice were killed and their organs, blood and tumours harvested for counting. Tumour localisation was four times greater than that into normal tissues, reaching 20% injected dose per gram of tumour. Eight patients have had this Tc99m-ICR12. Patient selection was by immunocytochemical staining of fine needle aspirates from the patient's own breast cancer. After intravenous administration of the immunoconjugate, tomographic images were obtained at 24 h. These results were compared to the subsequent histopathological examinations. Three patients acted as normal controls, one patient was negative due to inappropriate sampling, and two patients had strong membrane staining and provided excellent tumour localisation to both breast primary and regional node metastases. A further two patients only had moderate antigen expression on staining and did not localise well. The good performance of this radiolabelled antibody with patients that strongly stain for the antigen encourages the development of this system as both a method of staging breast cancer and a potential means of immunotherapy in this subgroup of patients.

Peptide compositions of the cerebrovascular and senile plaque core amyloid deposits of Alzheimer's disease

The pathological findings of Alzheimer's disease include amyloid deposition in cerebral blood vessels and in senile plaques. Both deposits are known to include peptides that contain a common sequence. Both forms of amyloid were isolated and their peptide compositions were determined. The peptides were resolved by size-exclusion chromatography in 70% formic acid, and reverse-phase chromatography in 60% formic acid, 0-40% acetonitrile. Senile plaque amyloid cores contain about 25% protein, about 70% of which is composed of peptides containing the beta-amyloid sequence. Amino-terminal sequencing of the core amyloid peptides (CAPs) revealed extensive amino-terminal heterogeneity, with variable amounts of blocked amino termini. Matrix-assisted, laser-desorption-time-of-flight mass spectrometry of the CAP mixture revealed an array of peptides the molecular weights of which corresponded to peptides beginning with each of the first 11 amino acids of the beta-peptide sequence and ending with Ala-42 of that sequence. The carboxyl-terminal residues were identified by tandem mass spectrometry of chymotrypsin digests. CAP possessed a minor degree of carboxyl-terminal heterogeneity. Cerebrovascular amyloid peptides (CVAPs) possessed minor degrees of both amino- and carboxyl-terminal heterogeneity. The major CVAP commenced at Asp-1 and ended at Val-40. Minor components of CAP possessed masses of 8000-9000 Da and the same amino-terminal residues as the major components of CAP. They may be precursors to the smaller CAPs. The differences in amino termini and carboxyl termini of CAPs and CVAPs suggest that the two types of amyloid form by different pathways, on which they encounter different proteases.

Immunotherapy of human tumour xenografts overexpressing the EGF receptor with rat antibodies that block growth factor-receptor interaction

Athymic mice bearing xenografts of human tumours that overexpress the receptor (EGFR) for EGF and TGF alpha have been used to evaluate the therapeutic potential of three new rat monoclonal antibodies (mAbs) directed against two distinct epitopes on the extracellular domain of the human EGFR. The antibodies, ICR16 (IgG2a), ICR62 (IgG2b) and ICR64 (IgG1), have been shown (Modjtahedi et al., 1993) to be potent inhibitors of the growth in vitro of a number of human squamous cell carcinomas because they block receptor-ligand interaction. When given i.p. at 200 micrograms dose, the three antibodies were found to induce complete regression of xenografts of the HN5 tumour if treatment with antibody commenced at the time of tumour implantation (total doses: ICR16, 3.0 mg; ICR62, 1.2 mg; ICR64, 2.2 mg). More importantly when treatment was delayed until the tumours were established (mean diam. 0.5 cm) both ICR16 and ICR62 induced complete or almost complete regression of the tumours. Furthermore, treatment with a total dose of only 0.44 mg of ICR62 was found to induce complete remission of xenografts of the breast carcinoma MDA-MB 468, but ICR16 was less effective at this dose of antibody and only 4/8 tumours regressed completely. ICR16 and ICR62 were poor inhibitors of the growth in vitro of the vulval carcinoma A431, but both induced a substantial delay in the growth of xenografts of this tumour and 4/8 tumours regressed completely in the mice treated with ICR62 (total dose 2.2 mg). Although ICR16 and ICR64 were more effective than ICR62 as growth inhibitors in vitro, ICR62 was found to be substantially better at inducing regression of the tumour xenografts due perhaps to additional activation of host immune effector functions by the IgG2b antibody. We conclude that these antibodies may be useful therapeutic agents that can be used alone without conjugation to other cytotoxic moieties.

Antitumor activity of combinations of antibodies directed against different epitopes on the extracellular domain of the human EGF receptor

The receptor (EGFR) for epidermal growth factor (EGF) and transforming growth alpha (TGF alpha) is often overexpressed in certain types of human malignancy and high levels of expression of the receptor and/or coexpression of growth factors. EGF and TGF alpha have also been correlated with poor prognosis in many patients. We have produced a number of rat monoclonal antibodies (MAbs) against four distinct epitopes on the external domain of the EGF receptor and are currently evaluating their potential for therapeutic use. Nine of these of MAbs were found to inhibit the binding of TGF and EGF to the receptor on tumor cells and these MAbs were able to inhibit the growth in vitro and in vivo of tumor cells that overexpress the EGF receptor. Here, we describe the results of experiments to determine the antitumor activity of combination treatment with two antibodies directed against separate epitopes on the external domain of human EGFR. Our results showed that treatment of human tumor xenografts with a combination of two anti-EGFR MAbs that bind to two distinct epitopes on the external domain of EGF receptor was not as effective as treatment with ICR62 alone, which binds to epitope C on the EGFR and is of IgG2b isotype. A phase I clinical trial with antibody ICR62 is currently underway in Royal Marseden Hospital (UK) in patients with head and neck and lung carcinomas.

Rat MAbs to the product of the c-erbB-2 proto-oncogene for diagnosis and therapy in breast cancer

The product of the c-erbB-2 protooncogene (p185) is a member of the EGF receptor family of transmembrane tyrosine kinases. Amplification of this gene and overexpression of the product has been observed in adenocarcinomas and has been correlated with poor prognosis in patients with breast and ovarian cancer. The very low levels of expression of p185 by normal adult tissues makes the receptor an almost tumor-specific target. We have prepared rat monoclonal antibodies against five distinct epitopes on the external domain of the c-erbB-2 product overexpressed by the breast cancer line BT474. The antibodies bind to the protein core of p185 and stain specifically the membranes in frozen sections of tumors overexpressing the c-erbB-2 product. Three of the antibodies, ICR12 (epitope A), ICR54, and ICR55 (epitope E), also stain the cell membrane in formalin-fixed, paraffin-embedded sections and bind to p185 in Western blots. An investigation of the stability of the antigen-antibody complexes indicates that the majority are not readily internalized by SKOV3 cells growing in vitro. Antibodies ICR12 (IgG2a) and ICR55 (IgG2a), which are directed against separate epitopes on the c-erbB-2 p185, are both of high affinity and immunoreactivity (> 75%) and localize specifically and stably to xenografted breast and ovarian carcinomas growing in athymic mice when labeled with 125I (up to 13% injected dose/g, ICR12 and ICR55) or a range of other radionuclides (up to 20% id/g, ICR12). We conclude that these antibodies may be useful as therapeutic vehicles for targeting radionuclides (imaging and therapy) or enzymes for activating prodrugs (ADEPT).

c-erbB2 protein overexpression in breast cancer as a target for PET using iodine-124-labeled monoclonal antibodies

ICR 12, one of a panel of rat monoclonal antibodies recognizing the external domain of the human c-erb B2 proto-oncogene product, (Styles, 1990) was chosen as a candidate for radiolabeling with 124I for positron emission tomography of selected patients with breast cancer. By using N-bromosuccinimide (NBS), optimal labeling conditions were established using 125I. The labeling efficiency was determined using instant thin-layer chromatography (ITLC) and gel filtration (HPLC). The antibody was then labeled with the positron emitter 124I, and a labeling efficiency of 96% and immunoreactivity of 80%-90% was obtained. The product was stable, with less than 5% of the radiolabel being eluted after six days storage in plasma at 37 degrees C. Immunolocalization studies were performed in athymic mice bearing human breast carcinoma xenografts overexpressing the c-erb B2 gene product using as controls 125I labeled isotype-matched rat antibody, and antigen-negative tumors. Good uptake of 124I-labeled ICR12 was obtained in c-erb B2 expressing tumors (up to 12% injected dose per gram at intervals up to 120 hr), with localization indices of 3.4-6.2. Tumor xenografts of 6 mm diameter were successfully imaged with high resolution at 24, 48 and 120 hr using the RMH/ICR MUP-PET camera. We suggest that 124I-labeled ICR12 is a suitable agent to image and quantify immunolocalization in patients whose tumors overexpress the c-erb B2 proto-oncogene product.

Circulating levels of epithelial membrane antigen in patients with breast or colorectal-cancer

Epithelial membrane antigen (EMA) is expressed by adenocarcinomas of the breast, ovary and colon and has been suggested as a circulating tumour marker. Serum EMA levels were measured in 126 patients, 31 with colorectal cancer, 52 with breast cancer and 43 age matched controls using a competitive binding radioimmunoassay and the rat anti-EMA monoclonal antibody (MAb) ICR2. The EMA levels in the control group varied widely from 90-3240ng/ml with a median value of 570ng/ml. This was not significantly different from the levels in patients with colorectal cancer (60-8530, median 580ng/ml) or those with breast cancer (210-13300, median 655ng/ml). However, the highest EMA levels (>5000ng/ml) were found in patients with cancer. The wide range of EMA levels in the control group prohibit its use for screening.

Prognostic importance of c-erbB-2 expression in breast cancer. International (Ludwig) Breast Cancer Study Group

PURPOSE

To evaluate the prognostic importance of immunocytochemically determined c-erbB-2 overexpression in the primary tumors of patients with breast cancer.

PATIENTS AND METHODS

Primary tumors from 1,506 breast cancer patients (760 node-negative and 746 node-positive) who were treated in the International (Ludwig) Breast Cancer Study Group Trial V were studied. Node-negative patients were allocated randomly to either a single cycle of perioperative chemotherapy (PeCT) or no adjuvant treatment, and node-positive patients received either a prolonged chemotherapy (with tamoxifen for postmenopausal patients) or a single perioperative cycle.

RESULTS

Tumors from 16% of the node-negative patients and 19% of the node-positive patients were found to be c-erbB-2-positive. In both groups c-erbB-2 positivity correlated with negative progesterone receptors (PR), negative estrogen receptors (ER), and high tumor grade. Lobular carcinomas were all negative, and, thus support the view that such tumors represent a defined subtype of breast carcinoma. The expression of c-erbB-2 was prognostically significant for node-positive but not for node-negative patients. However, in both subgroups, the prognostic significance was greater for patients who had received more adjuvant therapy. For node-positive patients, the effect of prolonged-duration therapy on disease-free survival (DFS) was greater for patients without c-erbB-2 overexpression (hazards ratio [HR], = 0.57; 95% confidence interval [CI], 0.46 to 0.72) than for those with c-erbB-2 overexpression (HR, 0.77; 95% CI, 0.51 to 1.16). Similarly, for node-negative patients, the effect of PeCT on DFS was greater for those without c-erbB-2 overexpression (HR, 0.82; 95% CI, 0.61 to 1.09) than for those with c-erbB-2 overexpression (HR, 1.22; 95% CI, 0.66 to 2.25).

CONCLUSION

We conclude that tumors with overexpression of the c-erbB-2 oncogene are less responsive to cyclophosphamide, methotrexate, and fluorouracil (CMF)-containing adjuvant therapy regimens than those with a normal amount of gene product.

Preoperative imaging of colorectal cancers. Targeting the epithelial membrane antigen with a radiation-labeled monoclonal antibody

The epithelial membrane antigen (EMA) is expressed by the majority of colorectal cancers but has not previously been investigated as a target for radiation-labeled monoclonal antibodies (MoAb) in the imaging of patients with colorectal cancer. A rat IgG2a MoAb that recognizes EMA, ICR2, was labeled with Indium-111 (100 megabecquerel per milligram [MBq/mg]MoAb) using the bicyclic anhydride of the chelating agent diethylene triamine pentacetic acid (ccDTPA) and was administered intravenously to 22 patients known to have or thought to have colorectal cancer. Daily gamma camera imaging was performed for 3 days during the time between the administration of the radiation-labeled antibody and surgical procedure. At operation, the biopsies were done of the tumors and the normal colon, and the uptake of radiation-labeled MoAb was measured in a gamma well-counter. Immunocytochemistry for EMA expression also was done on resected tumors. Independent unblinded and blinded reporting was done on all scans. The sensitivity of 111In-ICR2 for detecting cancers preoperatively was 80% and 60%, respectively, on unblinded and blinded reporting, and the corresponding specificity 20% and 60%. The low unblinded specificity was attributable to a false-positive localization in severely dysplastic benign tumors (n = 2) and inflammatory tissue (n = 2). Liver metastases present in three patients were cold relative to normal liver. Lymph node metastases were localized in 1 of 6 patients preoperatively. The mean absolute uptake of 111In-ICR2 in tumor tissue was 7.75 +/- 3.77 x 10(-3) percent of injected dose per gram, and the ratio to normal colon was 2.10 +/- 0.92:1. On immunohistochemistry, EMA was expressed by 16 of the 17 primary cancers, both dysplastic adenomas, and all nodal metastatic deposits. EMA-negative tumors (1 cancer + 1 colonic lipoma) had negative antibody scans, and patients whose tumor was negative or only focally positive for EMA expression had lower tumor/normal colon ratios of radioactivity (1.30 +/- 0.26 versus 2.45 +/- 0.65, P = 0.005) on gamma well-counting of excised specimens. These results suggest a possible role for 111In-ICR2 in the detection of colorectal cancer and metastases but not its liver deposits.

The effect of circulating antigen and radiolabel stability on the biodistribution of an indium labelled antibody

This study has investigated two of the main problems with radiolabelled antibody imaging, the formation of circulating immune complexes (I.C.) and the non specific binding of radiolabel to the antibody molecule. Patients undergoing immunoscintigraphy with 111In labelled monoclonal antibody ICR2 were divided into three groups who received either the radiolabelled antibody alone (control, n = 12), the radiolabelled antibody which was incubated with the chelating agent diethylene triamine pentacetic acid (DTPA) prior to size exclusion chromatography (n = 6) or whose injectate was treated with DTPA and cold MAb administered intravenously prior to radiolabelled MAb administration (n = 6). Radiolabelled antibody uptake in abdominal organs was measured by region of interest analysis using a gamma camera with online computer and that in tumour and normal tissues by gamma well counting of biopsies. Circulating antigen and immune complex was measured by high pressure liquid chromatography (HPLC). The sensitivity of tumour imaging and the tumour uptake of radiolabelled antibody was not significantly different between the groups. Patients with high circulating antigen levels developed high levels of circulating immune complex but also had high tumour uptakes of radiolabelled antibody. Administration of cold MAb increased the splenic, but did not effect the tumour uptake of radiolabelled antibody and only minimally reduced levels of circulating immune complex. Chelate administration reduced the urinary excretion of radioactivity but increased the liver uptake of radioactivity. These results have shown that successful antibody imaging can be carried out despite high levels of circulating antigen, that large doses of unlabelled antibody are required to prevent immune complex formation and that removal of non specifically bound 111In does not reduce the liver uptake of radioactivity.

Purification and tissue level of the beta-amyloid peptide precursor of rat brain

The beta-amyloid peptide precursor (beta-APP) exists in brain tissue as a membrane-associated protein extractable with 1% Triton X-100. beta-APP has been purified to near homogeneity by the following procedure: 1) anion exchange chromatography, 2) affinity chromatography on heparin agarose, and 3) immunoaffinity adsorption on matrix-bound antibodies directed to a synthetic peptide corresponding to the last 24 amino acids of the cDNA derived amino acid sequence of beta-APP. Conditions were chosen to minimize denaturation of the protein. The identity of the protein was confirmed by its immunoreactivity with antisera directed to five subsequences derived from the cDNA sequence. The amino-terminal sequence of beta-APP was found to be Leu-Glu-Val-Pro-Thr-Asp-Gly-Asn-Ala-Gly-Leu-Leu-Ala-Glu-Pro, which commences at residue 18 of the cDNA-derived primary structure. The procedure resulted in a 2000-fold purification of beta-APP. The purified protein migrated on polyacrylamide gels as a doublet of apparent molecular mass 100-120 kDa, although the predicted molecular mass of its constituent amino acids is 76 kDa. beta-APP clearly behaves anomalously in gel electrophoresis. The beta-APP content of rat brain amounted to 46 micrograms/g tissue. The half-life of the protein was calculated to be about 10 h, which is 30 times as long as that observed by others in transfected PC-12 cells. We conclude that transfected cell systems may not be adequate models for beta-APP processing.

Detailed investigation of the diagnostic value in tumour histopathology of ICR.2, a new monoclonal antibody to epithelial membrane antigen

The production and detailed immunostaining properties of a new rat monoclonal antibody (ICR.2) to epithelial membrane antigen are reported. The antibody was selected for its ability to compete with the polyclonal antiserum (M7), used in the original immunohistological studies, in order that it might serve as a direct replacement in diagnosing epithelial tumours. Most of the staining reactions on normal tissues were identical to those previously reported with M7 but there were some important differences. They included: positivity of renal and adrenal capsular fibroblasts, perineurium, some myoepithelial and smooth muscle cells, occasional osteoblasts and squamous and thyroid follicular epithelium in the normal state. The intercellular canaliculi of sweat glands and secretory canaliculi of gastric oxyntic cells were clearly demonstrated. These staining reactions could be obtained with M7 when a sensitive detection system was used although the results were usually weak and inconsistent. Nearly all adenosquamous and transitional carcinomas were positive. The remaining tumours fell into three major groups: (1) those which were consistently or nearly consistently negative--melanoma, seminoma, rhabdomyosarcoma, alveolar soft part sarcoma, adrenal cortical carcinoma, granulocytic sarcoma, paraganglioma, non-Hodgkin's lymphoma. Hodgkin's disease and embryonal carcinoma: (2) those which were either negative or positive with distinctive patterns of staining--basal cell carcinoma, embryonal tumours: and (3) non-epithelial tumours that were consistently positive--epithelioid sarcoma, synovial sarcoma, osteosarcoma, chordoma and myeloma--or positive in a significant minority of cases--leiomyosarcoma, malignant fibrous histiocytoma, clear cell sarcoma of tendon sheath, various neuroectodermal tumours.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of occult nodal metastases in patients with colorectal carcinoma

Immunohistochemical study may be used for detecting micrometastases by their expression of tumor-associated antigens. In 48 specimens of colorectal cancer from 47 patients, 49 of 249 lymph nodes (median, five per patient; range, 2-11) examined by light microscopic study contained tumor deposits. Sections of all lymph nodes were also examined by immunohistochemical study for carcinoembryonic antigen (CEA) and epithelial membrane antigen (EMA) expression using the indirect immunoperoxidase staining method. All 49 lymph node metastases (100%) from 20 patients stained positively for CEA and 45 (92%) expressed EMA. Of the 200 lymph nodes without metastases on light microscopic examination, anti-CEA revealed a single micrometastasis in a patient staged as Dukes' B. No additional metastases were detected with anti-EMA. In this series of patients immunohistochemical study has, therefore, influenced the histologic staging in only one patient (2%) and thus does not offer a significant benefit over conventional histologic staging.

Comparative study of carcinoembryonic antigen and epithelial membrane antigen expression in normal colon, adenomas and adenocarcinomas of the colon and rectum

The heterogeneous nature of tumour antigen expression may require selection of monoclonal antibodies on an individual patient or tumour basis to allow adequate tumour localisation. Carcinoembryonic antigen (CEA) and epithelial membrane antigen (EMA) expression has not previously been compared in colorectal cancer patients. Sections of cancer (n = 52), adjacent normal colon (n = 45), synchronous adenomas (n = 11) and nodal metastases (n = 49) were examined by indirect immunoperoxidase staining in 51 consecutive patients with colorectal cancer using monoclonal antibodies to CEA and EMA. The percentage of cells with positive staining in the primary tumours was graded 1: less than 25%, 2: 25-49%, 3: 50-75%, 4 greater than 75%. All primary colorectal cancers expressed CEA and 43 of 52 expressed EMA (83%). Grading showed CEA greater than EMA in 39, equal in 11 and less in two. Well differentiated cancers were more frequently graded three or four for CEA staining (23 of 27) than moderately differentiated cancers (11 of 22) (p less than 0.01). Equivalent figures for EMA were four of 27 and three of 22 (not significant) (NS) although the majority (86%) were graded 1 and 2. Grade 1 CEA expression was found in six of 15 proximal and only two of 37 distal lesions (p less than 0.01, chi 2 test) while for EMA equivalent figures were three of 15 and six of 37 (NS). Nodal deposits all expressed CEA and 45 of 49 expressed EMA (92%); 29 of 45 normal colon sections showed CEA expression (64%) as did all adenomas. EMA was not expressed by normal colon or adenomas. These results suggest that EMA expression is more specific but less sensitive than CEA for colonic cancer and is independent of tumour differentiation and site. Thus selecting monoclonal antibodies to CEA or EMA based on tumour biopsies may allow improved tumour localisation for imaging or therapy in patents with colorectal cancer.

Relationships among the cerebral amyloid peptides and their precursors

Alzheimer's disease is characterized by deposits of amyloid in cerebral blood vessels and neuropil. Qualitative analyses of partially purified preparations of these amyloid deposits revealed the presence of a unique polypeptide now often called "beta peptide". This peptide is 40 residues long and it exhibits some amino terminal heterogeneity, which may result from the isolation procedure. The major amyloid peptide comprises at least 30% of the dry mass and 70% of the protein of washed neuritic plaque cores. These results indicate that the major peptide is the predominant proteinaceous component of cores; furthermore, they demonstrate that although cores may contain other substances such as aluminum silicate, polysaccharides, and lipids, amyloid peptide is a major component. More careful analysis reveals that the core amyloid peptide differs significantly from cerebrovascular amyloid peptide. Although the core amyloid peptide is constructed of the same backbone as the cerebrovascular amyloid peptide, it contains modifications that render the amino terminal region uncleavable by Edman degradation or by trypsin. It is unknown whether the lower solubility of core amyloid is related to these modifications. The original impetus for characterizing the differences between the core and cerebrovascular amyloid peptides arose from the question of whether both amyloid peptides were formed by a sequential pathway. Our results showing that core amyloid peptide is more extensively modified than vascular amyloid leads us to conclude that if a sequential pathway exists, vascular amyloid peptide must precede core amyloid peptide. Nevertheless, the discovery that amyloid precursor mRNA is widely and abundantly distributed throughout most tissues tends to discourage such a simple account of the relationship between these forms of amyloid.(ABSTRACT TRUNCATED AT 250 WORDS)

A comparison of carcinoembryonic antigen (CEA) and epithelial membrane antigen (EMA) in human colorectal cancer

The development of monoclonal antibodies (MAbs) to tumour-associated antigens has allowed the successful radioimmunolocalization of a variety of tumours and has provided a basis for targeted therapy. In patients with colorectal cancer, antibodies to CEA have been the most widely used for imaging, but their role in targeted therapy may be inhibited by their reaction with normal tissues and with circulating CEA. Epithelial-membrane antigen (EMA) is expressed by most epithelial tumours, including colorectal cancers, and antibodies to EMA may provide a satisfactory alternative. We therefore compared two high-affinity MAbs, one to CEA (C46) and one to EMA (ICR2), in tissues obtained from 31 patients with cancer (18 primary colonic, 6 nodal metastases and 7 liver metastases), 14 patients with adenomatous polyps and 17 with normal colon. The indirect immunoperoxidase staining reaction was used and the results classified as either positive or negative. A heterogeneous pattern of staining was found for both antibodies. ICR2, the anti-EMA, reacted with slightly fewer colonic cancers than C46, the anti-CEA antibody (83% vs. 100%) and a similar number of metastases. Most noticeable was the minimal reaction of anti-EMA with normal colon (12% vs. 71%) and benign polyps (7% vs. 79%) in comparison to anti-CEA. This would suggest a possible role for ICR2 in the radioimmunolocalization and targeting of colorectal cancer.

The comparative immunoreactivities of brain amyloids in Alzheimer's disease and scrapie

An antibody was raised to a synthetic peptide corresponding to a published sequence for the first 24 residues of a cerebrovascular amyloid peptide (CVAP). Immunohistochemical staining of tissue sections revealed that the antibody bound extensively to cerebrovascular amyloid in Alzheimer disease (AD/SDAT) and Down's syndrome cases. The antibody bound less extensively to neuritic plaques (primitive and mature) and indetectably to neurofibrillary tangles. The antibody did not label scrapie plaques, scrapie-associated fibrils, or Gerstmann-Sträussler syndrome plaques. Immunoblotting experiments showed that the cerebrovascular amyloid peptide epitopes contaminating the neurofibrillary tangle preparations could be extracted with urea, leaving the neurofibrillary tangles intact. These data confirm that the cerebrovascular amyloid peptide is a component of cerebrovascular amyloid, and suggest that its epitopes are also components of neuritic plaque amyloid. The reduced level of immunostaining on amyloid cores in tissue sections suggests that either the cerebrovascular amyloid peptide epitopes are a minor component of amyloid cores, or that their mode of packing or state of processing in amyloid cores renders them relatively inaccessible to the antibody. We also conclude that the cerebrovascular amyloid peptide is not a component of neurofibrillary tangles. The synthetic cerebrovascular amyloid peptide possesses amyloid-like properties: at neutral pH it forms insoluble aggregates consisting of 5-7-nm fibrils, which form red-green birefringent adducts with Congo red and fluoresce with thioflavine S.

Methylated purines formed in DNA by dimethylnitrosamine in rats previously exposed to hepatotoxic and hepatocarcinogenic regimes: effects on the repair of O6-methylguanine

Studies of mammalian systems for the repair of O6-methylguanine in DNA have revealed large differences in the capacities of tissues and cells to perform this function and in the case of rat liver it has been shown that the O6-methylguanine repair system can be stimulated by exposure to hepatotoxic and hepatocarcinogenic regimes. In this report an assessment is made of possible relationships between toxic liver injury, DNA synthesis, cell proliferation and DNA repair by treating Wistar rats with agents selected to provide differing degrees of liver involvement. The effects of long-term (20 week) treatments with acetylaminofluorene (15 mg/kg/day), quinoxaline 1,4-dioxide (10 mg/kg/day), 4-aminobiphenyl-HCl (15 mg/kg/day) and pronethalol (20 mg/kg/day) were assessed, using the same strain of animals in which the original toxicity and carcinogenicity data were obtained. Repair of O6-methylguanine produced in liver DNA by a low, non-toxic dose (2 mg/kg) of [14C]dimethylnitrosamine was increased 3-4-fold throughout the period of treatment with acetylaminofluorene, to a lesser extent by quinoxaline 1,4-dioxide and 4-aminophenyl-HCl and not at all in the case of pronethalol. No evidence was obtained to indicate a direct relationship between O6-methylguanine repair and either the induced hepatotoxicity or the ensuing increased rates of DNA synthesis which occur following exposure to these agents.

Irreversible depression in the ratio of tetraploid:diploid liver nuclei in rats treated with 3'-methyl-4-dimethylaminoazobenzene (3'M)

A reduction in the ratio of tetraploid to diploid liver nuclei has been investigated as an early indicator of hepatocarcinogenesis in the rat using the liver carcinogen 3'-methyl-4-dimethylaminoazobenzene (3'M). In a dose ranging study 3'M was administered by gavage to rats at 5, 12.5 and 25 mg/kg for up to 10 weeks and the following parameters studied: bodyweight gain, dye binding to hepatic protein, nuclear ploidy in liver and histopathology. Significant reduction in bodyweight occurred only with 25 mg/kg; dye binding to protein occurred in a dose-related manner; depression of the percentage of tetraploid nuclei compared with diploids was dose-related and effects were detected even at the lowest dose. These observations were consistent with those from previous studies by other investigators. In a separate experiment 3'M was administered at the maximum tolerated dose (MTD) of 25 mg/kg for 3 weeks, during which time there was a significant reduction in bodyweight gain and a reduction in the ratio of tetraploid:diploid liver nuclei. After cessation of dosing the rate of bodyweight gain returned to normal but there was no corresponding recovery of the ratio of tetraploid:diploid nuclei in the liver. A long-term continuous gavage study at 2.5 mg/kg revealed a time dependent reduction in the ratio of tetraploid:diploid liver hepatocyte nuclei and histopathological changes that included hepatocarcinoma were also observed. There was no correlation between the severity of pathological changes and the change in nuclear ploidy ratio in this experiment and it is concluded that the changes in ploidy ratio are related to the carcinogenic effect of 3'M and are independent of its gross toxicity.

Initiation/promotion versus complete carcinogenicity in the rodent liver

4-N-Pyrrolidinylazobenzene (4N) is a close structural analog of the rodent liver carcinogen 4-dimethylaminoazobenzene (DAB). This structural similarity led us to evaluate it for genotoxic activity in vitro. We observed activity for 4N and DAB in the BHK cell transformation assay and subsequently in the Salmonella mutation assay of Ames. By a curious chance, Scribner, Miller and Miller, probably prompted by the same structural similarity, had synthesized 4N in the 1960s and found it to be noncarcinogenic to the rodent liver using a bioassay test protocol that detected DAB as carcinogenic. These findings were only described following the publication of our observations made in vitro. The conflict that apparently exists between these data can be interpreted in two separate ways. (a) Scribner et al. have suggested that 4N may be a carcinogenic initiator as opposed to a complete carcinogen like DAB. They also suggested that promotion of 4N-treated rodents with phenobarbitone might lead to the production of liver tumors. (b) We have evaluated the simpler concept that the activities observed for 4N in vitro define a carcinogenic potential that is not realized in vivo due to its rapid detoxification, at least in rodents. The first of these explanations implies that pure carcinogenic initiators may form a separate class of genotoxic agents from complete carcinogens, and perhaps of greater interest, that 4N might provide a valuable model compound for the study of carcinogenic promotion in the rodent liver. The second explanation regards potential carcinogenicity as a single property that can be defined in vitro and which may or may not be expressed in vivo depending on the enzymic environments encountered by the test chemical. It is clearly important to evaluate these different propositions in order to aid progress in the study of carcinogenic promotion, especially in the rodent liver. The presentation will describe our recent studies in vitro and in vivo in this connection.

4-Chloromethylbiphenyl (4CMB): a novel mutagen and potential carcinogen

The bacterial mutagenicity and cell transforming properties of the monocyclic alkylating agent benzyl chloride have been compared with those of its biphenyl analogue, 4-chloromethylbiphenyl (4CMB), and it is apparent that the addition of the second benzene ring greatly enhances biological activity. The possible reasons for this enhancement are discussed in relation to similar effects observed when comparing the activities of aniline with its biphenyl analogue, 4-aminobiphenyl (4AB). The marked activity observed for 4CMB, a stable and crystalline solid, suggests that it could prove useful as a direct-acting positive control test chemical for use in short-term mutagenicity tests.

Comparative activity of 4,4'-diaminobiphenyl (benzidine) and its terphenyl analogue, 4,4'-diaminoterphenyl, in two in vitro assays for potential carcinogenicity

The carcinogen 4,4'-diaminobiphenyl (benzidine) has been compared in vitro with its terphenyl analogue 4,4''-diaminoterphenyl using the Salmonella reverse mutation assay and the BHK cell-transformation assay. The responses observed, taken together with a consideration of chemical structures, indicate that the terphenyl compound is a potential carcinogen. These findings may contribute to an understanding of the mechanism of action of benzidine as a carcinogen.

Evaluation in vitro of several pyrrolizidine alkaloid carcinogens: observations on the essential pyrrolic nucleus

Six compounds related to pyrrolizidine alkaloids have been subjected to an in vitro mammalian cell transformation test. Two hepatocarcinogenic alkaloids (retrorsine and monocrotaline) and one synthetic analogue (synthanecine A bis-N-ethylcarbamate) gave positive results while a non-toxic alkaloid (rosmarinine) was negative in the test. Positive results were also given by dehydroretronecine, a secondary pyrrolic alkaloid metabolite, and the closely related synthetic compound 2,3-bishydroxymethyl-1-methylpyrrole. These observations lend support to the hypothesis that a simple alkylating pyrrole is the biologically active chemical agent derived from these alkaloids. The negative transformation response observed for the non-carcinogenic alkaloid rosmarinine establishes that the carcinogenic alkaloids are inducing transformation rather than simply selecting for spontaneous transformants. The mammalian-derived cells used in this study, unlike S. typhimurium, were capable of activating retrorsine in the absence of an auxiliary source of metabolising enzymes (S-9 mix).

Continuous ventilation and oedema

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