Cellular basis of induced alpha-fetoprotein synthesis by hepatocytes of adult mouse after hepatotoxic injury and partial hepatectomy

Serum AFP levels in patients suffering from 47 different types of cancers and noncancer diseases

Alpha-fetoprotein (AFP) is a glycoprotein and belongs to the gene family of serum albumins. The serum AFP levels were found to be elevated in the sera of liver cancer patients in 1964 and were subsequently developed and used as a liver cancer biomarker. However, elevated serum AFP levels have been observed in patients suffering from other cancer and noncancer diseases. Up to date, a systematic comparison of the serum AFP levels in different diseases has not been reported. In current study, 66,682 clinical lab test results of serum AFP levels from healthy individuals and patients with 47 different types of diseases during the past 5 years were retrieved and analyzed. Based on the mean (SD), median, and p (-Log₁₀p) values, we found that patients suffering from liver, breast, esophagus, cervical, pancreatic, endometrial, gastric, lung, rectum cancers in addition to noncancer diseases cirrhosis, nephrotic syndrome, and gastritis had significantly (p<0.05) increased, whereas patients suffering from multiple myeloma, Wilms' tumor, and other 22 types of noncancer diseases had significantly decreased median serum AFP levels than that of healthy controls. Moreover, patients with liver cancer, cirrhosis, lymphoma, bone fracture, and Wilms' tumor had highest mean serum AFP levels and the biggest SD values. In summary, the increased serum AFP levels were most evident but not specific for liver cancer patients. The potential clinical use of the increased or decreased serum AFP levels for other types of cancer and noncancer diseases and the molecular mechanisms behind our current findings need to be investigated.

Mouse alpha-fetoprotein gene 5' regulatory elements are required for postnatal regulation by raf and Rif

The mouse alpha-fetoprotein (AFP) gene is expressed at high levels in the yolk sac and fetal liver and at low levels in the fetal gut. AFP synthesis decreases dramatically shortly after birth to low levels that are maintained in the adult liver and gut. AFP expression can be reactivated in the adult liver upon renewed cell proliferation such as during liver regeneration or in hepatocellular carcinomas. Previously, two unlinked genetic loci that modulate postnatal AFP levels were identified. The raf locus controls, at least in part, basal steady-state AFP mRNA levels in adult liver. Rif influences the extent of AFP mRNA induction during liver regeneration. Transgenic mice were used to examine the role of 5' AFP regulatory regions in raf- and Rif-mediated control. A fragment of the AFP 5' region containing enhancer element I, the repressor, and the promoter was linked to the mouse class I H-2Dd structural gene. We demonstrate that this hybrid AFP-Dd transgene is expressed in the appropriate tissues. In addition, it is postnatally repressed and reactivated during liver regeneration in parallel with the endogenous AFP gene. Therefore, proper transcriptional control does not require the AFP structural gene. Furthermore, the AFP 5' control region is sufficient to confer raf and Rif responsiveness to the linked H-2Dd structural gene, suggesting that raf and Rif act at the level of transcriptional initiation.

Mouse alpha-fetoprotein gene 5' regulatory elements are required for postnatal regulation by raf and Rif

The mouse alpha-fetoprotein (AFP) gene is expressed at high levels in the yolk sac and fetal liver and at low levels in the fetal gut. AFP synthesis decreases dramatically shortly after birth to low levels that are maintained in the adult liver and gut. AFP expression can be reactivated in the adult liver upon renewed cell proliferation such as during liver regeneration or in hepatocellular carcinomas. Previously, two unlinked genetic loci that modulate postnatal AFP levels were identified. The raf locus controls, at least in part, basal steady-state AFP mRNA levels in adult liver. Rif influences the extent of AFP mRNA induction during liver regeneration. Transgenic mice were used to examine the role of 5' AFP regulatory regions in raf- and Rif-mediated control. A fragment of the AFP 5' region containing enhancer element I, the repressor, and the promoter was linked to the mouse class I H-2Dd structural gene. We demonstrate that this hybrid AFP-Dd transgene is expressed in the appropriate tissues. In addition, it is postnatally repressed and reactivated during liver regeneration in parallel with the endogenous AFP gene. Therefore, proper transcriptional control does not require the AFP structural gene. Furthermore, the AFP 5' control region is sufficient to confer raf and Rif responsiveness to the linked H-2Dd structural gene, suggesting that raf and Rif act at the level of transcriptional initiation.

Liver cell necrosis and regeneration following injections of carbon tetrachloride. Effects of the thyrotropin-releasing hormone and somatostatin

Mice were given 10 micrograms somatostatin or 25 micrograms TRH intraperitoneally 10 min before s.c. injection of 2 or 20 mg CCl4. The extent of liver cell necrosis and nuclear size were measured by the electronic Mini Mop method and the extent of necrosis and nuclear pleomorphism were estimated by a visual linear analogue scale of 100 mm, and compared to plasma concentrations of ASAT and ALAT. Pre-treatment with TRH or somatostatin resulted in significant reduction in the extent of necrosis 24 h after CCl4-injections (25%), with a lowering of ASAT from 13209 +/- 2955 U/l to 5144 +/- 924 after TRH and to 6186 +/- 966 after somatostatin, and of ALAT from 14343 +/- 3209 to 7718 +/- 1727 and 6494 +/- 1253 U/l, respectively. After 3 days the necroses were reduced from 16.5 +/- 1.7% by the Minimop method to 1.4 +/- 0.5% (90%) in mice given CCl4 alone, and from 12.3 +/- 1.7% to 3.8 +/- 1.2% in mice pretreated with TRH, and from 12.3 +/- 1.8% to 3.8 +/- 1.7% (70%) in mice pretreated with somatostatin. The plasma concentrations of ASAT and ALAT were reduced correspondingly. After 5 days no necroses were seen, and the plasma ASAT and ALAT were normal. After 6 months of weekly injections of TRH or somatostatin before 20 mg CCl4 the liver cell nuclear size (10.5 and 9.7 0.3 mu 2) was similar to that after CCl4 alone (9.7 0.3 mu 2), and twice that of controls (4.6-5.4 0.1 mu 2). Liver cell necrosis was not seen. The plasma concentrations of ASAT (131 8.6-162 11.3) and ALAT (98 8-104 9 Iu/l) were similarly 2-3 times those in controls. TRH and somatostatin thus reduced liver cell injury and delayed regeneration after single injections of CCl4. After 6 months of weekly injections no effects were observed.

In situ cellular analysis of alpha-fetoprotein gene expression in regenerating rat liver after partial hepatectomy

Cellular analysis of hepatic alpha-fetoprotein gene expression in normal adult rat and during regeneration induced by partial hepatectomy was performed at the cellular level by in situ hybridization using 35S-labeled complementary DNA probes and immunoperoxidase techniques. In normal adult rat liver sections, a few alpha-fetoprotein mRNA-cDNA hybrids are detected over all hepatocytes. No protein is detected with routine immunoperoxidase methods. However, after in vivo colchicine blockade of alpha-fetoprotein secretion, 10 to 20% alpha-fetoprotein-positive hepatocytes are observed. In regenerating livers, at 2,6 and 24 hr (before and at the time of the peak of DNA synthesis in the periportal zones), a rise of the nuclear signal level is observed selectively in periportal hepatocytes, without modification of the cytoplasmic signal. At 48 hr (when most hepatocytes have completed at least one replicative cycle), almost all hepatocytes throughout the liver lobule display a rise of the nuclear (2- to 3-fold) and cytoplasmic (1.5- to 2-fold) signal level compared to nonoperated rats. These data show that all hepatocytes in the adult liver express a small number of alpha-fetoprotein mRNA sequences; they appear to be translated in protein whose secretion can be blocked by colchicine. The moderate increase in alpha-fetoprotein gene expression induced by liver regeneration takes place in all hepatocytes, in apparently two distinct steps: a very early nuclear accumulation of alpha-fetoprotein mRNA sequences and a late cytoplasmic accumulation of alpha-fetoprotein mRNA molecules.

Investigations concerning the correlation between liver cell proliferation, production of alpha-fetoprotein, and DNA-synthesis of lymphocytes in the spleen of NMRI-mice. An autoradiographic and immunohistochemical study

To obtain more information concerning the correlation between liver cell proliferation, production of alpha-Fetoprotein (AFP) and DNA-synthesis of lymphocytes in the central and peripheral parts of periarteriolar lymphatic sheaths ( PALS ) of the spleen, these parameters were monitored in intervals of 12h after CCl4-poisoning of NMRI-mice using autoradiographic and immunohistochemical methods. The results indicate that synthesis of AFP is not linked closely to proliferation of hepatocytes because in contrast to DNA-synthesis the production of AFP was only detectable in a very small subpopulation of liver parenchymal cells reaching a peak before the majority of hepatocytes was found to enter the S-phase of the cell cycle. Beyond this, in vivo no general suppressive effect of AFP on proliferation of lymphocytes in preferably T-dependent areas of the spleen could be detected since the 3H-TdR-labeling index in these compartments increased, reaching a peak 48h after the maximum of hepatocytes producing AFP had occurred.

Alpha-fetoprotein synthesis in relation to structural peculiarities in postnatal and regenerating mouse liver

The localization of alpha-fetoprotein (AFP) and of antigens of liver-cell plasma membrane (Ag I, Ag II and Ag III) was studied in adult, postnatal and regenerating (CCl4 or paracetamol-treated mouse liver). Ag I, Ag II and Ag III were solubilized by Triton X-100 from ghosts of the mouse liver cells. The purification of antigens was performed by gel filtration on Sephadex G-200 or Ultrogel ACA-54 with subsequent treatment of antigenic fractions eluted from the column with 5% HClO4. Ag I and Ag II are common for liver and some other mouse organs, but Ag III is strictly specific for liver. The Ag I is predominantly found in the region of the bile capillaries. Ag II and Ag III are mainly present on membrane adjoining blood sinusoids. The distribution of these three antigens in newborn mouse liver is quite different from that in adult liver and reflects the specific arrangement of hepatocytes at different stages of development - the acinar structure in newborn liver and the plate structure in the adult organ. During regeneration as well as during postnatal development, AFP has been found in areas of marked tissue rearrangement. In both cases, these areas lose the plasma membrane antigens, especially Ag I - the antigen of bile capillary. The reappearance of Ag I on the surface of liver cells coincides with cessation of AFP synthesis and establishment of definitive plate structure. The possible role of liver plate structure in the regulation of AFP synthesis is discussed.

Oncodevelopmental and hormonal regulation of alpha 1-fetoprotein gene expression

The main features of the oncodevelopmental biology of alpha 1-fetoprotein (AFP) are reviewed. Progress made in the molecular biology of AFP gene regulation is discussed and we present our recent data on the mechanisms of AFP suppression by glucocorticoid hormones. The relationship between AFP gene transcription and cell replication is examined, and it is suggested that the degree of methylation of the AFP gene (or of co-methylated regulatory DNA sequences) conditions its response to hormones.

Distribution of mRNAS of fibrinogen polypeptides and albumin in free and membrane-bound polyribosomes and induction of alpha-fetoprotein mRNA synthesis during liver regeneration after partial hepatectomy

To study the effect of regenerative response of the liver following partial hepatectomy on the synthesis of major plasma proteins (secretory proteins), we have determined the sequence contents and the distribution of albumin and fibrinogen polypeptide mRNAs in rat liver at intervals after partial hepatectomy and sham operation. Using a quantitative technique for the isolation of polyribosomes, we demonstrated that the distribution of RNA between free and membrane-bound polyribosomal fraction was unchanged in these experiments. There was no shift in the polyribosomal population to favor free polyribosomes after partial hepatectomy. However, there was a dramatic increase (5-6-fold) of the fibrinogen polypeptide mRNA concentration during the first 24 h after resection. In contrast, the albumin mRNA concentration decreased (2-3-fold). There were no alpha-fetoprotein mRNA sequences detectable in any liver RNA fraction in these experimental animals. In sham-operated rats with intact livers, similar changes of fibrinogen polypeptide and albumin mRNA concentrations as described in regenerating liver after partial hepatectomy, were observed. These results suggest that albumin and fibrinogen synthesis after partial hepatectomy is reciprocally regulated at the mRNA level and represents a nonspecific acute phase response to surgical trauma.

Alpha-fetoprotein: cellular origin of a biological marker in rat liver under various experimental conditions

Alpha1-fetoprotein (AFP) was detected by serological, light and electron microscopic methods in various experimental models. These included (a) liver regeneration after partial hepatectomy or CCl4 intoxication (mouse and rat); (b) liver intoxication by high doses of N-nitrosomorpholine (NNM) and chemical induction of hepatomas (rat). AFP levels varied greatly according to the animal species and strains used. Low and high AFP-producing species and strains were distinguished. In liver regeneration after hepatectomy or CCl4 intoxication, cellular AFP was found in the cytoplasm of hepatocytes. In NNM-intoxicated livers, elevated AFP levels were associated with proliferation of canalicular epithelial cells in which AFP was localized. In early stages of hepatocarcinogenesis, significant AFP increase occurred after high-dose carcinogen feeding and AFP was also localized in proliferating canalicular epithelial cells. On low-dose NNM feeding, no cellular AFP was detected unless hepatomas had developed. At the stage of malignant conversion, distinct AFP staining and non-AFP staining hepatocellular carcinomas appeared in livers.

Elevation of serum alpha-fetoprotein in anemic patients

Alpha-fetoprotein (AFP) is present in the serum of normal healthy adults; an increase in level has been found as a rule in patients with diseases that can affect the liver. In the course of routine examination, we encountered a moderate increase in serum AFP in some patients with acute bleeding anemia, not accompanied by elevation of serum transaminase levels. We examined the relationship between anemia and serum AFP levels, using CIS kits for the assay. The least detectable concentration of below 0.25 ng/ml, which was two standard deviations outside the value obtained for the zero-dose response, was measurable by a two-step incubation: pre-incubation of serum and antiserum followed by addition of [125I]AFP and further incubation. The mean AFP level in 75 normal control sera was 2.4 1.6 ng/ml. There was a significant increase in the mean value of serum AFP levels in acutely anemic patients with no evidence of liver involvement. The increase was moderate, many of the patient samples being within the normal range. The reticulocyte counts did not correlate with the elevated AFP levels, indicating low significance of extra-hepatic AFP synthesis. A moderate increase in AFP production might occur in acutely anemic patients with no detectable hepatic cell damage.

Laminin and fibronectin in cell adhesion: enhanced adhesion of cells from regenerating liver to laminin

Laminin, a basement membrane glycoprotein isolated from cultures of mouse endodermal cells and rat yolk sac carcinoma cells, promoted the attachment of liver cells obtained from regenerating mouse liver. Cells from normal mouse liver attached readily to dishes coated with fibronectin but attached poorly to surfaces coated with laminin. Both proteins efficiently promoted the attachment of cells from livers undergoing regeneration. After regeneration, the attachment to laminin returned to the low levels found in animals not subjected to partial hepatectomy but attachment to fibronectin remained high. Immunofluorescent staining of sections of normal liver with antilaminin revealed the presence of laminin in or adjacent to the walls of the bile ducts and blood vessels. After induction of regeneration by partial hepatectomy, increased amounts of laminin appeared in the sinusoidal areas. After carbon tetrachloride poisoning, staining for laminin was especially pronounced in the necrotic and postnecrotic areas around the central veins. This additional expression of laminin was transient. It reached a maximum around 5--6 days after the injury and then gradually disappeared. These findings show that laminin is an adhesive protein. The increase of laminin in regenerating liver and the adhesiveness of cells from such livers to laminin suggest a role for laminin in the maintenance of a proper tissue organization during liver regeneration.