Effect of basic fibroblast growth factor on synthesis/secretion of pS2 protein by human breast cancer cells (MCF-7)

pS2 is an estrogen-induced mRNA species that was originally identified in the breast cancer cell line MCF-7. Exposure of the cells to basic fibroblast growth factor (bFGF) at the concentration of 10-100 ng/ml for 48-72 h resulted in a marked increase in the concentration of pS2 protein in the medium. The polymerase chain reaction with reverse transcriptase revealed that bFGF increased the amount of intracellular pS2 mRNA: immunocytochemical studies showed that exposure to the factor increased the amount of intracellular pS2 protein. Simultaneous addition of cycloheximide with bFGF completely abolished induction of pS2 protein, although it did not affect the induction of pS2 mRNA. Actinomycin D did not affect the stimulatory effect of bFGF on synthesis/secretion of pS2 protein. bFGF effectively abolished decay of the pS2 mRNA level caused by actinomycin D. These results suggest that the induction of the synthesis/secretion of pS2 protein by bFGF occurs at the post-transcriptional level, most probably due to the stabilization of pS2 mRNA. Another finding, that bFGF and estradiol have a synergistic effect on induction of pS2 protein, suggests the possibility that these two inducers act by a different but partly overlapping mechanism.

Dynamic aspects of glutathione metabolism in obstructive jaundice

The dynamic aspects of glutathione metabolism during obstructive jaundice were analyzed in rats. Plasma bilirubin levels increased after ligation of the bile duct, with a concomitant increase in hepatorenal glutathione levels. When the bile duct was recanalized, plasma bilirubin levels rapidly decreased, with a concomitant decrease in hepatorenal glutathione levels. The half-life of hepatic glutathione turnover increased markedly after bile duct obstruction, returning to normal after recanalization of the bile duct. Intravenous administration of a loading dose of bilirubin inhibited the biliary secretion of glutathione in a dose-dependent manner. On the other hand, renal glutathione efflux increased markedly after bile duct obstruction. These observations suggest that glutathione status is significantly affected in obstructive jaundice, predominantly due to the inhibition of hepatic secretion by increased bilirubin.

Two hepatitis C virus glycoprotein E2 products with different C termini

Processing of the boundary region between the putative structural and nonstructural regions of the hepatitis C virus precursor polyprotein was analyzed by in vitro translation using reticulocyte lysate in the presence of canine microsomal membranes. At this boundary in the precursor polyprotein, the most carboxy-terminal of the structural proteins, gp70 (E2), is proximal to the amino terminal of the nonstructural protein p21 (NS2). The presence of a novel microsomal membrane-dependent cleavage site was observed at the region upstream of the amino-terminal end of p21 (NS2) in the precursor polyprotein. The cleavage site was assigned to amino acid residues 746/747 in the hepatitis C virus precursor polyprotein. Inefficient cleavage of this site resulted in the production of two forms of E2 products with different sizes of peptide backbones. Translation and cleavage of various C-terminal deletion constructs established the significance of the C-terminal hydrophobic amino acid sequences of E2 products in membrane anchoring.

Molecular organization of bacteriochlorophyll in chlorosomes of the green photosynthetic bacteriumChloroflexus aurantiacus: Studies of fluorescence depolarization accompanied by energy transfer processes

Examination was made of changes in fluorescence polarization plane by energy transfer in the chlorosomes of the green photosynthetic bacterium,Chloroflexus aurantiacus. Fluorescence anisotropy in the picosecond (ps) time region was analyzed using chlorosomes suspended in solution as well as those oriented in a polyacrylamide gel. When the main component of BChlc was preferentially excited, the decay of fluorescence anisotropy was found to depend on wavelength. In the chlorosome suspension, the anisotropy ratio of BChlc changed from 0.31 to 0.24 within 100 ps following excitation. In the baseplate BChla region, this ratio decreased to a negative value (-0.09) from the initial 0.14. In oriented samples, the degree of polarization remained at 0.68 for BChlc, and changed from 0.25 to -0.40 for the baseplate BChla by excitation light whose electric vector was parallel to the longest axis of chlorosomes. In the latter case, there was a shift from 0.30 to -0.55 by excitation perpendicular to the longest axis. Time-resolved fluorescence polarization spectra clearly indicated extensive changes in polarization plane accompanied by energy transfer. The directions of polarization plane of emission from oriented samples were mostly dependent on chlorosome orientation in the gel but not on that of the polarization plane of excitation light. Orientations of the dipole moment of fluorescence components was consistent with that of absorption components as determined by the linear dichroism (Matsuura et al. (1993) Photochem. Photobiol. 57: 92-97). A model for molecular organization of BChlc anda in chlorosomes is proposed based on anisotropic optical properties.

Cytokine regulation of PS2 gene expression in mouse astrocytes

Treatment of astrocytes with interleukin (IL)-6, -7 and tumor necrosis factor (TNF)-alpha produced a marked increase in the expression of the pS2 gene, an estrogen-inducible gene originally identified in the human breast cancer cell line MCF-7. The effect of IL-6 and TNF-alpha was completely inhibited by the addition of anti-IL-6 monoclonal antibody and anti-TNF-alpha monoclonal antibody, respectively. During the treatment with IL-6 and TNF-alpha, neither increase in thymidine incorporation nor morphological change was observed. Inhibition of protein synthesis by cycloheximide and inhibition of RNA synthesis by actinomycin D abrogated the stimulatory effect on pS2 mRNA expression of IL-6 and TNF-alpha, suggesting that new protein synthesis as well as new RNA synthesis was required for their action. These results suggest that brain injury trigger pS2 gene expression in astrocytes through the induction of cytokines.

Studies on rat hepatic hydroxysteroid sulfotransferase--immunochemistry, development and pI variants

Rat hepatic hydroxysteroid sulfotransferase with sulfoconjugates androsterone (androsterone-sulfating sulfotransferase) is an oligomer consisting of several subunits with distinct pI values but with the same molecular mass (pI variants). N-terminal amino acid sequences of the pI variants are all identical. The enzyme is exclusively present in the liver, in which its lobular localization is sex-dependent. The localization of the enzyme is markedly different from that of an isoenzyme of phenol sulfotransferase. In weanling and adult female rats, the relative abundance of the pI variants is different. During development from weanling stage to adulthood, the amounts of acidic variants increase, whereas the relative levels of alkaline variants remain constant.

An immunohistochemical study of the distribution of blood group substances and related antigens in primary colorectal carcinomas and metastatic lymph node and liver lesions, using monoclonal antibodies against A, B, H type 2, Le(a), and Le(x) antigens

Using indirect immunoperoxidase staining, we examined the distribution of blood group substances and related antigens, including Le(a), A, B, H type 2, and Le(x), in 87 carcinomas and 42 normal mucosal specimens of colon and rectum, as well as in metastatic lesions of 32 lymph nodes and 9 liver specimens. The compatible expression rate of A/B/H type 2 antigens was 33.3% (3/9) in proximal normal colon, but only 6.1% (2/33) in distal normal colon. Compatible expression was observed in 14 of 25 carcinomas in the proximal colon (56.0%), but these antigens in distal colon cancers reappeared with a high positive rate, 62.9% (39/62). The rate of H type 2 accumulation with the deletion of A and/or B antigens was 6.9% (6/87). Incompatible expression was not observed in colorectal cancer. Le(a) and Le(x) antigens were expressed in normal mucosa and primary carcinoma throughout the colon. Le(a) and Le(x) in primary carcinoma that showed A/B deletion with/without H type 2 accumulation was expressed more than in carcinoma with A/B/H type 2 compatible expression (88.2% vs 71.7% for Le(a); 94.1% vs 88.7% for Le(x), respectively). In 16 of 32 patients (50.0%), A/B/H type 2 antigen expression in metastatic lesions had disappeared or was decreased compared with that in primary carcinoma, followed by metastasis to regional lymph nodes. These results suggested that: (a) A/B/H type 2 blood group substances in the distal colon behave as tumor-associated antigens in colorectal carcinoma. (b) Most frequently, A/B/H type 2 antigens expressed in primary carcinoma were weakened or had disappeared in metastatic lymph nodes. Further investigation of the biological function of carbohydrate chains, such as those of blood group substances and related antigens on cancer cell surfaces may lead to a solution of the problem of the metastatic behavior of tumor cells.

pS2 gene especially expressed in the late G1/S phase of mouse astrocytes

By the reverse transcription-polymerase chain reaction we investigated the localization of pS2 mRNA, which encodes a secreted polypeptide of 60 amino acids with unknown function, in the adult mouse. This method revealed that the expression of pS2 mRNA was not restricted to the stomach as previously reported but was also found in various other tissues such as brain, heart, spleen, and muscle. The pS2 mRNA was additionally detected in astrocytes cultured from the whole brain of the newborn mouse. The pS2 expression in these astrocytes increased with cell growth and sharply declined after the cells reached the stationary phase. In the cells synchronized by the serum deprivation-refeeding technique, the expression of pS2 mRNA was only found at late G1 and S phase. These results suggest that the transcripts of pS2 gene are widely distributed throughout the entire body of the mouse and that they play some important cell cycle-related role in these tissues.

An immunohistochemical employer monoclonal antibodies against Le(a), sialyl Le(a), Le(x), and sialyl Le(x) antigens in primary colorectal, carcinomas and lymph node and hepatic lesions

The immunohistochemical expression of sialylated and non-sialylated forms of both Le(x) and Le(a) were studied in 87 carcinomas and 42 normal mucosal specimens of colon and rectum, as well as in 32 metastatic lymph nodes and 9 hepatic lesions, using an indirect immunoperoxidase staining. Their antigens were expressed in normal mucosa with the following frequencies: Le(a), 95.2% (40/42); sialyl Le(a), 88.1% (37/42); Le(x), 95.2% (40/42); and sialyl Le(x), 17.0% (7/42), whereas in carcinomas, the respective rate of frequency were: 78.2% (68/87); 78.2% (68/87); 90.8% (79/87); and 93.1% (81/87). Sialyl Le(x) antigen showed the highest tumor specificity compared to other antigens. In three normal mucosal specimens and four carcinomas with Le(a-b-) phenotype, the expression of type 1 antigens (Le(a) and sialyl Le(a)) was not consistent, whereas type 2 antigens (Le(x) and sialyl Le(x)) were consistently observed in carcinomas. The staining of type 1 antigens and Le(x) was decreased in metastatic lesions compared with primary carcinomas, whereas sialyl Le(x) antigen had the same positive-staining rate in both. Metastatic carcinoma expressed the sialylated form more predominantly than the non-sialylated form in type 2 antigens whereas the opposite result was observed in type 1 antigens. These results suggested that: (a) sialyl Le(x), defined by monoclonal antibody CSLEX1, may be useful as a tumor-associated antigen in colorectal carcinoma, and (b) the alteration of Lewis-related carbohydrate antigens in cancer cell membranes, including sialylation and/or aberrant glycosylation, may be related to metastatic behavior.

Changes in nerve growth factor content of the submaxillary gland in the genetically dystrophic (mdx) mouse

We evaluated the nerve growth factor (NGF) contents in the submaxillary gland of the mdx mouse, a model for Duchenne muscular dystrophy (DMD), and found that the NGF and NGF mRNA contents in this organ, where extraordinarily high amounts of NGF are synthesized and stored independently of development or maintenance of the nervous system, were markedly elevated in the male mdx mouse at 8 and 11 weeks of age. However, the NGF content of this organ in 4-week-old male mdx mice was lower than that of control mice although statistical significance of difference was not observed. In the mdx female mouse, the submaxillary NGF content was significantly lower than that of the normal mouse at 4 weeks of age, but was similar to that of the normal at 8 and 11 weeks of age. The amounts of epidermal growth factor (EGF), another protein that is known to be sexually and developmentally regulated in the mouse submaxillary gland like NGF, was found to be also significantly increased in this organ of the male mdx mouse at 8 and 11 weeks of age, and to be significantly decreased in that of the female mdx mouse at 4 weeks of age. The parallel changes in NGF and EGF contents during development of the submaxillary gland suggest that the mdx mouse suffers from some abnormality in the development of this organ.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of p53 protein expression and cellular localization in human and hamster pancreatic cancer cell lines

We compared the expression of p53 protein in four human pancreatic cancer cell lines (HPAF, CD11, CD18 and PANC-1) and four hamster pancreatic cancer cell lines (PC-1, PC-1.2, PC-1.0 and H2T) by the monoclonal antibodies PAb421 and PAb240. PAb421 reacted with all human pancreatic cancer cell lines but not with the hamster cells. PAb240, on the other hand, reacted with all human and hamster pancreatic cancer cell lines in immunoblotting and in immunocytochemistry. However, immunoprecipitation with PAb240 was detected only in human cell lines HPAF, CD11 and CD18 cells but not in PANC-1 or in any of the hamster cell lines. During exponential growth, immunoreactivity was detected mainly in the nucleus of PC-1, PC-1.2 and PANC-1 cells (nuclear type) and in both the nucleus and the cytoplasm of PC-1.0, H2T, HPAF, CD11 and CD18 cells (diffuse type). At the confluence, the expression of p53 was decreased in most of the human cell lines as was proliferative cell nuclear antigen. After incubation with 1 mM hydroxyurea, cells with nuclear p53 expression did not show an altered cellular distribution of p53 protein, whereas cells with a diffuse type of localization pattern showed an increase in the nuclear staining. On the other hand, cytoplasmic immunoreactivity was found in PC-1.0, PC-1, PC-1.2, HPAF, CD11 and CD18 cells that were treated with 100 ng/ml of nocodazole. After heat stress with 1 h incubation at 42 degrees C, p53 protein was detected in the cytoplasm and nucleolus of all cell lines. After 24-48 h incubation at 37 degrees C, this change in cellular distribution of p53 in response to heat stress was reverted to a preheat stress pattern. The overall results suggest that neither the p53 of PANC-1 nor the hamster pancreatic cancer cell lines are immunoprecipitated with the PAb240. It appears that cell cycle and heat stress are two of the factors that influence cellular localization of p53 protein in both human and hamster pancreatic cancer cells.

Immunohistochemical expression of sialyl Lex antigen in relation to survival of patients with colorectal carcinoma

BACKGROUND

The alterations of carbohydrate chains in cancer cell membrane can be related, not only to the formation of tumor-associated antigens, but also to cell biologic significance. There is, furthermore, a possibility of their relationship to tumor metastatic behavior and subsequent survival of patients with cancer. Recent clinical studies elucidated that a carbohydrate antigen, sialyl Lex, is a useful tumor marker in colorectal cancer. However, the sialyl Lex antigen immunoreactivity in colorectal carcinoma in relation to patient survival is unknown. The aim of the study was to elucidate whether sialyl Lex expression in tumors was correlated with patient survival.

METHODS

Immunohistochemical expression of sialyl Lex antigen, as detected by monoclonal antibody CSLEX1, was studied in 175 specimens of primary colorectal carcinoma from 120 patients who received radical surgery.

RESULTS

The positive expression of sialyl Lex was observed in 87 of 120 patients (72.5%). There was no statistically significant association between the negative or positive of sialyl Lex and clinicopathologic factors, excluding Dukes stage and histologic type. The difference between overall 5-year survival of patients with sialyl Lex-negative tumors and that of patients with sialyl Lex-positive tumors (81.2% versus 60.6%) was statistically significant (P = 0.0263). In proportion to staining intensity that was expressed as a score based on the percentage of the total field stained positive with CSLEX1, 5-year survival of patients indicated a worse outcome (P = 0.0113). The prognostic value was then studied in a Cox regression model. Dukes stage had the strongest association with patient survival, whereas sialyl Lex expression was found to be the second-ranking parameter.

CONCLUSIONS

When examining the expression of sialyl Lex antigen, as detected by monoclonal antibody CSLEX1, clinically useful information for patient survival after radical resection of colorectal cancer is given.

Elevation of tumor-associated carbohydrate antigens in patients with diffuse panbronchiolitis

We investigated the serum levels of the tumor-associated carbohydrate antigens sialyl SSEA-1 (SLX) and sialyl Lewis(a) (CA19-9) in patients with diffuse panbronchiolitis (DPB) and other nonmalignant lung diseases. Both antigens were high in the serum and bronchoalveolar lavage fluid (BALF) of patients with DPB, bronchiectasis (BE), idiopathic pulmonary fibrosis (IPF), and interstitial pneumonia associated with collagen vascular disease (CVD). Markedly high levels of the antigens were demonstrated in the serum and BALF from patients with DPB. An immunohistochemical study of open-lung biopsy specimens from patients with DPB indicated that these antigens were selectively expressed on the bronchiolar epithelial cells and mucinous exudates in airspaces. Low-dose, long-term erythromycin (EM) treatment was recently reported to be effective for DPB, and we investigated its influence on serum and BALF antigen levels in DPB patients. Antigen levels in both serum and BALF decreased after EM treatment, with improvement of symptoms and laboratory data, and there was a significant correlation between the reduction in the SLX level in serum and neutrophil percentage in BALF pre- and post-EM treatment. Our result suggests that secreted carbohydrate antigens from the bronchiolar epithelium in DPB may appear in the serum as a result of airway damage in the lower respiratory tract, and serum levels of the antigens may be decreased by a reduction in neutrophils in BALF after EM treatment.

UDP-GalNAc:Fuc alpha 1-2Gal alpha 1-3GalNAc transferase activity in hamster pancreatic cancers and in normal hamster alimentary tissues

Ductal adenocarcinomas induced by N-nitrosobis(2-oxopropyl)amine treatment in Syrian hamsters produce blood group-A antigen, which is not present in normal hamster pancreas. To understand the underlying mechanism of A antigen neoexpression in pancreatic cancer cells, we examined the activity of UDP-GalNAc:Fuc alpha 1-2Gal alpha 1-3GalNAc transferase (A-transferase), the enzyme responsible for blood group-A antigen production. The specific activity of A-transferase in the pancreatic cancers was approximately 8 nmol/mg protein/h in membrane preparations, 0.3 nmol/mg protein/h in whole cell extracts, and undetectable in normal hamster pancreas. Significant A-transferase activity was found in normal tissues expressing blood group-A antigen. Although both normal (gastric antrum, colon) and pancreatic cancer cells showed similar enzymatic characteristics (optimal pH, substrate affinity, optimal [Mn2+]), there was a difference in the requirement for divalent cations. The A-transferase in cancer cells showed a more stringent requirement for Mn2+. These results suggest that A-transferase is activated during nitrosamine-induced pancreatic carcinogenesis, which results in the neoexpression of blood group-A antigen. The difference in divalent cation requirements between A-transferase activities of cancer and normal cells may indicate that there are multiple A-transferases present in hamster tissues.

Glycan structure of blood group-A antigen in hamster normal tissues and pancreatic cancers

Pancreatic cancers induced by N-nitrosobis(2-oxopropyl)amine in Syrian hamsters produce blood group A antigen. The glycan structure of the blood group A antigen-bearing glycoproteins purified from pancreatic cancer cells has been shown previously to be bound to Asn-linked complex oligosaccharides. Because blood group A antigen has usually been described as being on Ser/Thr-linked glycans, the distribution and glycan-protein linkage of the antigen were examined in normal hamster tissues in comparison with the findings on pancreatic cancer cells. The gastrointestinal tract, excluding the small intestine, expressed blood group A antigen. The liver, pancreas, and gallbladder did not show blood group A reactivity. Blood group A antigen in the proximal gastrointestinal tract was resistant to peptide N-glycosidase F digestion, which cleaves Asn-linked glycans from core proteins. Blood group A antigen was peptide N-glycosidase F sensitive in membrane preparations from pancreatic cancers. In the colon, this antigen was only partially removed by peptide-N-glycosidase F. These results demonstrate a difference in the structure of blood group A antigen-associated glycan between pancreatic cancers and normal hamster gastrointestinal tissues.

Interleukin-4 and -5 as modulators of nerve growth factor synthesis/secretion in astrocytes

To examine the regulation of nerve growth factor (NGF) gene expression with respect to neural trauma, we examined the effects of T cell-derived lymphokines on NGF synthesis/secretion in cultured mouse astrocytes. Interleukin (IL)-4 and IL-5 significantly increased the amount of NGF secreted by astrocytes, whereas IL-2, IL-3, and IL-6 had no significant effect. IL-4 and IL-5 produced marked increases in NGF mRNA levels in astrocytes as demonstrated by the reverse transcription-polymerase chain reaction (RT-PCR) method. The effect of IL-4 and IL-5 was greater in quiescent astrocytes than in growing cells. Neither increase in thymidine incorporation nor any morphological change was observed during the treatment with IL-4 and IL-5. The stimulatory effect of IL-4 and IL-5 on NGF synthesis was completely inhibited by the addition of anti-IL-4 monoclonal antibody and anti-IL-5 monoclonal antibody, respectively. The results indicate that IL-4 and IL-5 specifically trigger a cascade of events to regulate NGF synthesis in astrocytes, independent of cell growth.

Production of scatter factor-like activity by a nitrosamine-induced pancreatic cancer cell line

Two hamster pancreatic cancer cell lines, PC-1 and PC1.0, established from N-nitrosobis(2-oxopropyl)amine-induced pancreatic ductal/ductular adenocarcinomas exhibit different growth patterns. PC-1 cells, which produce well differentiated adenocarcinomas in vitro after allogeneic inoculation, form cell aggregates and characteristic island-like structures in vitro. PC1.0 cells, which produce poorly differentiated tumors in vivo, form dispersed colonies in vitro. Conditioned medium prepared from PC1.0 cells inhibits PC-1 cells from forming island-like colonies. The conditioned medium also prevents several human pancreatic carcinoma cell lines, HPAF, CD11 and CD18, from forming compact colonies. These properties are similar to those described previously as scatter factors. The scatter factor-like activity is heat-labile, acid-stable, non-dialyzable, trypsin sensitive and unaffected by reducing agents. The activity is not suppressed by addition of heparin, and it does not bind to heparin. In addition, the scatter phenomenon is not reproduced by acidic or basic fibroblast growth factor, epidermal growth factor or transforming growth factor-beta 1. Based on these findings, it appears that the scattering activity produced by PC1.0 cells differs from the scatter factors that have been identified in other systems.

Relationship between blood group-A antigen expression and malignant potential in hamster pancreatic cancers

The loss of expression of the ABH blood group antigens is suggested to be associated with more aggressive behavior of cancers. We have compared the growth behaviors of two hamster pancreatic cancer cell lines with different blood group-A expressions. PC-1.0 cells, which expressed blood group-A antigen poorly, showed a faster growth in vitro and in vivo when implanted into the pancreas of homologous animals, whereas PC-1.2 cells, all of which express the antigen, had a slower growth rate both in vitro and in vivo. PC-1.0 also tended to metastasize, whereas PC-1.2 cells grew primarily locally. The allografts of both PC-1.2 cells (PC-1.2AG) and PC-1.0 cells (PC-1.0AG) and the metastases of PC-1.0 cells expressed blood group A antigen in a similar rate. There was no significant difference in the number of A-antigen positive cells (A+) between the PC-1.2AG and PC-1.0AG, although the expression of A antigen in PC-1.0AG showed a greater heterogeneity. The combined immunohistochemistry and autoradiography did not show any significant differences in the labeling index of A+ or A- cells between the two allografts. Thus, the results indicate that blood group A antigen expression is unrelated to malignancy in this model. The faster growth rate of PC-1.0 cells may be due to their shorter cell cycle.

Purification and analysis of glycoproteins bearing blood group-A determinants from hamster pancreatic ductal adenocarcinomas

Although the hamster pancreas does not express A, B or H blood group antigens, all hamster pancreatic ductal adenocarcinomas induced by treatment with N-nitrosobis(2-oxopropyl)amine express blood group-A antigen. Thus, the acquisition of blood group-A antigen expression in this system is a cancer-associated alteration. We have purified three major blood group-A antigen bearing glycoproteins (gp120, gp135 and gp150) from hamster pancreatic cancer cell membrane preparations using affinity chromatography on DBA (Dolichos biflorus) agglutinin-agarose. When assayed by immunoblotting, gp120 and gp135 showed strong blood group-A reactivity, which was removed by treating membrane samples with peptide-N-glycosidase F. Blood group-A reactivity was unchanged by treatment of the membrane fractions with endoglycosidases F and H. In addition, these two glycoproteins bearing blood group-A antigen also bound L-PHA (Phaseolus vulgaris leucoagglutinin). These results demonstrate that gp120 and gp135 express blood group-A antigen on Asn-linked multi-antennary complex type glycan structures. The gp150 showed weak blood group-A expression. This is the first demonstration of the neoexpression of cancer-associated blood group-A determinants which reside on Asn-linked glycan structures.

Modification of blood group A antigen expression in a pancreatic cancer cell line (PC-1) by inhibitors of N-glycan processing

Pancreatic adenocarcinomas induced in Syrian hamsters by treatment with N-nitrosobis(2-oxopropyl) amine express blood group A antigen, which is absent in normal pancreatic cells. On membrane glycoproteins purified from tumors, blood group A antigen has been found to be expressed on multiantennary Asn-linked complex glycans. In this study, we investigated the effect of inhibitors of Asn-glycan processing on blood group A antigen bearing glycan structures in a cell line (PC-1) established from a primary induced pancreatic cancer. Expression of blood group A antigen on cells and in membrane preparations was blocked by treatment with 1-deoxymannojirimycin, an inhibitor of mannosidase I, but was retained after treatment with swainsonine, an inhibitor of mannosidase II. However, swainsonine treatment altered the glycan structure associated with blood group A antigen from an endoglycosidase H resistant type to a sensitive type, indicating that the blood group A structure might shift from a complex type to a hybrid type glycan by this treatment. These results demonstrate that Asn-linked glycans carry the major blood group A antigens in PC-1 cells.

Expression of pS2 gene in human breast cancer cell line MCF-7 is controlled by retinoic acid

We established a simplified method for the quantitative measurement of pS2 mRNA using the reverse transcriptase-polymerase chain reaction (RT-PCR) method. Expression of the pS2 gene, which is transcriptionally induced by estrogen in breast cancer cell line MCF-7 cells, can be repressed by retinoic acid (RA) in unstimulated cells. The suppressive effect of RA on pS2 mRNA was inhibited by cycloheximide.

Chalcone tetramers, lophirachalcone and alatachalcone, from Lophira alata as possible anti-tumor promoters

Two chalcone tetramers were isolated as inhibitors of Epstein-Barr virus (EBV)-activation induced by a tumor promoter, teleocidin B-4, from a medicinal plant in tropical west Africa, Lophira alata (Ochnaceae). One of them was identified as lophirachalcone. The other, named alatachalcone, was new, and the structure was determined by spectral properties. Both compounds also showed potent inhibitory activities against teleocidin B-4-induced inflammation on mouse ear. In an initiation-promotion experiment on mouse skin, alatachalcone (16 nmol) significantly inhibited tumor promotion caused by 12-O-tetradecanoylphorbol-13-acetate (TPA, 1.6 nmol).