Carcinofetal human isoferritins

Expression of p43 in breast cancer tissue, correlation with prognostic parameters

Placental isoferritin (PLF) and its unique superheavy chain p43 have been recently described as being synthesized by breast cancer cell lines but not by normal breast epithelial cells. Since previous reports have demonstrated a correlation between the content of 'normal' ferritin in breast cancer tissue and the degree of differentiation and prognosis, we have determined p43 in the cytosol of 122 breast cancer samples by use of the new monoclonal antibody CM-H-9. The synthesis of p43 showed a significantly negative correlation with tumor size (P = 0.0001), histologic grading (P = 0.0038), nuclear pleomorphism (P = 0.0019), rate of mitosis (P = 0.0002), lymphocytic reaction (P = 0.0001) and a significantly direct correlation with estrogen receptor status (P = 0.0009). Although patients with a higher p43 content showed a trend for a better outcome (median follow-up: 61.4 months), an independent influence of the cytosolic p43 content on survival could not be confirmed by a multiple Cox model. Therefore it seems that p43's prognostic impact is linked to the highly significant correlation with features of differentiation although a statistical bias in the Cox model due to the limited number of patients must also be taken into account. On the other hand, the significant correlation of p43 expression with factors for good prognosis was striking and consistent and warrants further research of this tumor product.

Determination of placental ferritin (PLF)-positive lymphocytes in women in early stages of breast cancer

Previous studies have proved that a certain acidic isoform of ferritin is specifically synthesized by the placenta and breast-cancer tissue. In this context it has been further reported that the determination of this so-called placental isoferritin (PLF) on the surface of a subset of peripheral lymphocytes is highly specific and sensitive for early stage breast cancer. By use of the monoclonal antibody CM-H-9 and flow cytometry, the levels of placental ferritin (PLF)-positive cells were determined in 133 female patients undergoing surgical excision of a controversial or highly suspicious lesion of the breast detected by mammography. In addition, 61 healthy blood donors served as controls. Values of PLF-positive cells in breast cancer patients differed significantly from those found in women with benign diseases and healthy controls (3.87% vs. 1.55% and 2.02, respectively; p less than 0.00001). Analysis of prognostic factors in breast cancer patients (tumor size, lymph-node status, menopausal status, estrogen receptor status, histologic grading and grading subfactors) revealed significantly higher levels of PLF-positive cells in lymph-node-negative patients compared with node-positive patients (p less than 0.00001). Furthermore, levels of PLF-positive cells showed a significantly negative correlation with tumor size and nuclear polymorphism. In 15 patients who underwent a guide-wire-directed surgical biopsy for a non-palpable, mammographically suspect lesion, 4 cases of cancer correlated with high values of PLF-positive lymphocytes while only 1 patient with a benign histologic result exhibited more than 4% positive cells.

Placental isoferritin associated p43 antigen correlates with features of high differentiation in breast cancer

Placental isoferritin (PLF), an acidic isoform of ferritin, and its unique superheavy chain p43 have been recently described to be synthesized by breast cancer cell lines but not by normal breast epithelial cells. Since previous reports have demonstrated a correlation between the content of 'normal' ferritin in breast cancer tissue, degree of differentiation, and prognosis, we have tried to evaluate the correlation of p43 in the cytosol of 122 breast cancer samples with commonly applied prognostic factors and features of proliferation and differentiation. In parallel, we investigated the correlation of p43 expression in MCF-7 and T47-D breast cancer cell lines during proliferation induced by estradiol plus fetal calf serum (assessed by 3H-thymidine incorporation), compared to p43 expression in stationary non-stimulated cell cultures. The levels of p43 in breast cancer cytosols correlated significantly negatively with tumor size (p = 0.0001), histologic grading (p = 0.0038), nuclear pleomorphism (p = 0.0019), rate of mitosis (p = 0.0002), and lymphocytic reaction (p = 0.0001), and significantly directly with the estrogen receptor status (p = 0.0009). Although patients with a higher p43 content showed a trend for a better outcome (median follow-up: 61.4 months), an independent influence of the cytosolic p43 content on survival could not be confirmed by a multivariate Cox model. In accordance with the observed negative correlation of features of differentiation vs. p43 expression, induction of proliferation by estradiol plus FCS added to serum-free tissue culture medium correlated with a decrease of p43 synthesis in both cell lines. Expression of p43 in estrogen and FCS-absent media revealed also a decrease in relation to a low spontaneous proliferation. However, the drop of p43 synthesis was significantly stronger in cell lines with estrogen-stimulated proliferation. Our in vitro and cytosol results confirm recent clinical observations describing an inverse correlation of p43 synthesis with the degree of proliferation and differentiation in breast cancer. However, the pathologic mechanisms leading to this phenomenon as well as the negative correlation with lymphocytic infiltration are still unclear and need to be further elucidated.

Placental isoferritin (PLF) in comparison with MCA and CEA in advanced breast cancer--first data from a pilot study

The development of new and effective marker substances has optimized tumor-marker-guided follow-up programs to monitor generalization of disease and to assess the therapeutic outcome. Isoferritins of placental origin were first determined in the serum of patients with lymphoproliferative disease by way of the recently developed monoclonal antibody CMH-9. We have set up an Austro-Israeli working group and analysed 64 patients in terms of the sensitivity of placental ferritin (PLF) compared with the standard markers carcinoembryonic antigen (CEA) and mucinous-like cancer-associated antigen (MCA) in patients with metastatic breast cancer. We have additionally evaluated the importance of combined marker determination. Analysis of the data in view of site of metastatic spread yielded satisfying results both for PLF (sensitivity 70.4%) as well as MCA (sensitivity 76.9%) for visceral metastases; a combination of these two markers revealed a striking sensitivity of 88.4%, which, however, could not be improved by adding the third marker (CEA). With regard to non-visceral metastases, CEA and MCA were clearly superior.

Monoclonal antibody CM-H-9 detects circulating placental isoferritin in the serum of patients with visceral metastases of breast cancer

The aim of the current pilot study was to determine whether placental isoferritin (PLF) can be detected in the serum of patients with metastatic breast cancer. Sera were obtained from breast cancer patients with metastatic disease (n = 100), from breast cancer with no evidence of disease (n = 70) and from healthy female controls (n = 34). PLF and total serum ferritin levels were independently measured using specific monoclonal antibody ELISAs in a double-blind study. It was found that the mean serum PLF levels were significantly elevated only in patients with visceral metastases (lung, liver, brain) compared with the levels of patients with non-visceral metastases (bone, skin) or with healthy controls. Contrary to this, analysis of total serum ferritin levels did not reveal significant differences between these groups. Considering 0-10 units/ml as a PLF negative result, it was found that PLF was negative in 87.5% of healthy controls and in 96% of breast cancer patients with no evidence of disease. In contrast, PLF was positive in 73% of the patients with visceral metastases and in 29.7% of those with non-visceral metastases. The striking difference between visceral and non-visceral metastases is not yet understood. It could result from a difference in the degree of vascularisation or, alternatively, a difference in the cell types and genes expressed by cells metastasizing to visceral or non-visceral organs.

Ferritin: an expanded role in metabolic regulation

Synthesis of ferritin, a constitutive protein, is increased by iron. This protein is well recognized as a protein which detoxifies, stores and transports iron. The 24 subunits of ferritin assemble to form a protomer of Mr 480,000. This protein shell can sequester up to 4500 g atoms of iron as ferrichydroxyphosphate. Ferritin in vitro and in vivo binds other metal ions such as Cu, Zn, Cd, Pb, Be and Al. Next to Fe it binds large quantities of Be. Therefore, in vitro ferritin protects against and reverses the inhibition by Be of enzymes susceptible to this metal ion. Also, rats pretreated with Fe survive otherwise toxic levels of either pulmonary or intravenous exposure of Be. Liver ferritin from rats injected with Zn contains some of the injected metal ion. Incubation of such ferritin-zinc complex with zinc-requiring apoenzymes restores their activity. Fe(III) of ferritin is released only after its reduction to Fe(II) by a reductant. Incubation of phosphoglucomutase, a phosphoserine containing enzyme with ferritin and a reductant causes irreversible inactivation of the enzyme and removes 70% of its phosphate. Some other phosphoproteins are similarly inactivated but without the loss of the bound phosphate. Thus, uncontrolled release of iron from ferritin, in the presence of a reductant and oxygen can modify several biomolecules and can affect metabolic processes. A subclass of ferritin, acidic isoferritins, have been implicated in leukemia-associated inhibitory activity and has been suggested to inhibit production of Ia+ macrophage progenitors.

Possibly unique subunit(s) of human ferritins responsible for tissue specificity

The biochemical characteristics of human placental and hepatic ferritins were compared. By DEAE cellulose column chromatography, placental ferritin was found to contain more acidic isoferritins, while hepatic ferritin was richer in basic isoferritins. The electrofocusing patterns of subunits revealed that placental ferritin contained at least one unique subunit on the acidic side and might lack one subunit on the basic side as compared with hepatic ferritin. It is hypothesized that microheterogeneities, immunological as well as biochemical, existing between placental and hepatic ferritins cannot be explained merely in terms of different proportions of known acidic and basic subunits, but appear to have resulted from the existence of the unique acidic subunit of placental ferritin and possibly also a unique basic subunit of hepatic ferritin.

Isolation and characterization of Phycomyces blakesleeanus ferritin

Ferritin was isolated from the fungus Phycomyces blakesleeanus and compared biochemically and immunologically with horse spleen ferritin. Phycomyces and horse spleen ferritins were shown to exhibit similar electrophoretic patterns on polyacrylamide gels. Both preparations yielded an identical single band on sodium dodecyl sulfate-containing polyacrylamide gels. Tryptic digests of Phycomyces ferritin yielded 17 ninhydrin-positive spots as compared to 26 for horse spleen ferritin tryptic digests. Phycomyces ferritin was immunologically unrelated to horse spleen ferritin.

Ferritin, a sensitizing substance in the leucocyte migration inhibition test in patients with malignant lymphoma

The nature of the factor in Hodgkin's disease involved spleen to which many patients with malignant lymphoma react in the leucocyte migration inhibition test has been investigated. Our results suggest that ferritin from Hodgkin's disease involved spleens is antigenically different to that prepared from normal spleen. Isoelectric focusing shows the presence of more acidic 'isoferritins' in ferritin prepared from Hodgkin's disease involved spleen than in that prepared from normal spleen. Further observations using the leucocyte migration inhibition test suggest that sensitization to the abnormal ferritin, acting as an onco-fetal tumour associated substance, may be responsible for the reaction of patients with malignant lymphoma in this test.

Serum ferritin assay

Ferritin is an iron storage protein of high-molecular weight which is primarily present in the liver, spleen, and bone marrow. A very sensitive immunoradiometric assay has been developed which permits determination of serum concentrations in normal persons and in patients with a variety of different disorders. In normal subjects, the serum ferritin concentration correlates very well with total body iron stores as measured by phlebotomy. The serum ferritin concentration is reduced in patients with iron-deficient anemia and is significantly higher in patients who are anemic for other reasons. Subject areas discussed in this review include the details of the immunoradiometric procedure, the sensitivity and accuracy of the assay, factors influencing the assay, values characteristic of a variety of clinical disorders, and the utility of the assay in clinical medicine and public health.

Theoretical mechanisms for synthesis of carcinogen-induced embryonic proteins. I. Alpha-fetoprotein induction by ethionine

The neoplastic cellular phenotype expresses many embryonic features. These features are believed to occur by derepression of embryonic genes during the carcinogenic process. A specific case is the ability of ethionine, a hepatocarcinogen, to induce an embryonic protein known as alpha-fetoprotein. A mechanism is proposed for this derepression process along with supporting evidence. It is hypothesized that the repressor protein for the alpha-fetoprotein gene must be modified (methylated) before it is functional and if for any reason this does not occur, alpha-fetoprotein will be produced. This simple theory can explain a variety of states of the liver cell in which alpha-fetoprotein is expressed namely i) fetal, ii) ethionine-treated, iii) neoplastic, and iv) tyrosinemic liver cells.

Human leukaemia associated antigen (LAA): occurrence and characteristics

Serum leukaemia-associated antigen (LAA) is identified as an oncofetal antigen (or antigens) since it is present in fetal liver and in amniotic fluid. Although it is mainly found in patients with proliferative haematological disorders, particularly acute leukaemias and chronic myelogenous leukaemia, LAA is occasionally present in sera from healthy people. In protein fractionation experiments, LAA behaves as a distinct population of molecules and has the characteristics of an alpha2-beta-globulin, not carrying any lipids. The origin of LAA in haematological disorders is unknown. Its presence does not correlate with high white blood cell count, although antibody to LAA has been raised in animals injected with blast cells from leukaemia patients. LAA is distinct from alpha-fetoprotein, and we have observed a reaction of immunological non-identity between LAA and ferritin. This is of considerable interest since ferritin has been reported to be immunologically closely related to alpha2H-globulin which may occur in the same categories of patients as LAA. It is preliminary concluded that LAA as defined by our antisera may be different from alpha2H-globulin and ferritin.

Alpha-fetoprotein

Despite all the information about AFP presented, a great deal still needs to be discovered especially in pregnancy. Geographical and racial differences remain to be elucidated. Similarly, differences in obstetric population in Helsinki and Baltimore, for example, are only now being studied. Sex differences may exist; Lardinois and associates195 cited a higher level of AFP in male than female fetuses. The important questions that need to be answered are whether AFP assays can help improve the other half of prenatal care- that directed to the fetus- and whether the AFP model can help enhance our understanding of the similarities and differences of fetal and cancer cells.