Establishment and characterization of human ovarian carcinoma cell lines

Five human ovarian carcinoma cell lines cultured from primary and metastatic tumors of Korean patients were characterized. These lines were isolated from two papillary serous cystadenocarcinomas, two endometrioid carcinomas, and one malignant Brenner tumor. It was shown that the growth of these cell lines was stable when cultured after at least 20 passages. Population doubling times varied from 40 to 67 hr. All lines showed high viability and were proven by DNA fingerprinting analysis to be unique. Contamination by mycoplasma or bacteria was excluded. In two lines, SNU-8 and SNU-840, an elevated level of CA125 antigen secretion could be detected, whereas CEA was undetectable in all five lines. Four different mutations in functional and highly conserved regions of the p53 gene were identified in three of our five lines (60%), namely in SNU-119, SNU-251, and SNU-563. Included were two missense mutations, one in-frame 3-base-pair deletion, and one out-of-frame 1-base-pair deletion. It is interesting to note that one of these three lines, SNU-251, presented an additional simultaneous nonsense mutation of the BRCA1 gene and missense mutation of the hMLH1 gene. In its lacking both wild-type alleles of the BRCA1 gene, SNU-251 might serve as an unusual and important in vitro model for studies related to ovarian carcinoma and the BRCA1 gene. It is thus likely that the establishment and characterization of these permanent human ovarian carcinoma cell lines in continuous cultures can provide useful tools for in vitro studies related to human ovarian carcinomas.

Establishment and characterization of 12 uterine cervical-carcinoma cell lines: common sequence variation in the E7 gene of HPV-16-positive cell lines

A total of 12 carcinoma cell lines of the human uterine cervix were established from 5 keratinizing and 5 nonkeratinizing squamous-cell carcinomas, and 2 small-cell carcinomas. Of these, 10 lines grew as adherent cells and 2 as floating aggregates. All lines showed (i) similarity in morphology to the primary tumor from which they were derived; (ii) high viability with relatively long doubling times (48-96 hr); (iii) absence of Mycoplasma and other bacteria, apart from one Mycoplasma-contaminated line; (iv) genetic heterogeneity by DNA-fingerprinting analysis; (v) absence of p53 mutation from exon 4 through 9; and (vi) the presence of HPV DNA sequence. Among the lines, 7 were infected by HPV-16, 3 by HPV-18, 1 by HPV-31, and 1 by HPV-33; the 2 cell lines derived from small-cell carcinomas contained HPV-18. Interestingly, 6 of the 7 cell lines containing HPV-16-type DNA harbored the same alteration of E7 at nucleotide position 647 (amino acid 29, AAT --> AGT, Asn --> Ser), whereas the 3 HPV-18-positive lines did not; 3 cell lines proved to have intact E1/E2 of HPV, suggesting the presence of episomally replicating HPV DNA as well as the integrated form, whereas the other 9 lines were shown to have integrated HPV. Taken together, these cell lines would be very useful for studying the biology of uterine cervical carcinoma.

DNA methylation patterns and sequence transitions of the CpG island of mouse Hprt during early embryogenesis

The timing and pattern of methylation of the CpG island in the X-chromosome gene, Hprt, was examined using bisulfite methods to assess the occurrence of DNA cytosine methylation at the onset of X-chromosome inactivation (XCI). The Hprt sequences were extensively methylated in 4.5 dpc blastocysts, and the levels of methylation progressively decreased to 7.5 dpc. Adult patterns of methylation were established in the embryonic tissues after 7.5 dpc. By contrast, methylation continued to decrease in extraembryonic lineages and at 13.5 days was not detectable on the paternal Hprt sequences in the yolk sac endoderm. In the bisulfite-treated coding strand, numerous G to A transitions and CpTpG methylations were observed that were unique to the methylated or nonmethylated Hprt sequences, respectively, in early development.

X-chromosome inactivation in hybrid embryonic carcinoma cells upon differentiation

We have analyzed Xist expression before and after the differentiation of embryonic carcinoma (EC) cell hybrids to address whether these hybrids undergo X inactivation on differentiation in vitro and whether this process (X inactivation) is random. In this work, we analyzed Xist expression using RT-PCR as a way of monitoring the X-chromosome activity in EC hybrid cells. No Xist expression was observed in OTF9 or in its hybrid cells, indicating that all X chromosomes were active in these cells. In contrast, retinoic acid-induced differentiated cells expressed as high levels of Xist as female primary cells. Polymorphism for HaeIII sites of the amplified Xist cDNA revealed that both Xista and Xistb alleles were expressed in differentiated cell population. These results indicate that X inactivation occurred in a random process during differentiation of OTF9 hybrid cells in vitro.

Establishment and characterization of human gastric carcinoma cell lines

We report 8 newly established gastric-carcinoma cell lines (SNU-216, 484, 520, 601, 620, 638, 668, 719) from Korean patients. Morphologic study was carried out using light and electron microscopes. CEA, alpha FP, and CA 19-9 and TPA in supernatant and in cell lysate were measured by radioimmunoassay. p53 and c-Ki-ras gene mutations were screened and confirmed by sequencing. The cell lines, derived from tumors with moderate differentiation, grew as a diffuse monolayer, and those from tumors with poor differentiation and minimal desmoplasia grew exclusively as non-adherent. Out of the 8 gastric-cancer cell lines, 5 had detectable levels of CEA both in supernatant and in cell lysate; there was no expression or secretion of alpha FP in these cells; 4 cell lines showed high levels of CA 19-9 in cell pellets. All cell lines except SNU-484 had high concentrations of TPA both in cell lysate and in supernatants. p53 mutation was found in 6 cell lines (75%): 2 (SNU-216 and SNU-668) had mutations in exon 6, and other 3 in exon 8. The c-Ki-ras mutation was found in 2 cell lines (25%), SNU-601 and SNU-668. The former showed GGT-to-GAT transition mutation at codon 12, while the latter showed CAA-to-AAA transversion mutation at codon 61. DNA profiles using restriction endonuclease HinfI and polymorphic DNA probes ChdTC-15 and ChdTC-114 showed different unique patterns; which suggests that these cell lines are unique and not cross-contaminated. We believe that the newly characterized gastric-cancer cell lines presented in this paper will provide a useful in vitro model for studies related to human gastric cancer.

Frequent association of alternative splicing of NER, a nuclear hormone receptor gene in cancer tissues

We have detected frequent alternative splicing of a gene that encodes NER, a protein homologous to the retinoic acid receptors, in cancer cells. Western and immunohistochemical analyses disclosed accumulation of a large amount of the aberrant NER product, generated by alternative splicing that caused skipping of an exon corresponding to the DNA-binding domain, in the nucleoli of cells of cancer cell lines and primary cancer tissues. The aberrant protein was detected in 116 of 228 primary cancers developed in various tissues including breast and colon, but was absent in the corresponding normal tissues; it was also detected in 31 of 39 cancer cell lines. This observation may imply that the aberrant NER product has some relation to the development and/or progression of cancers in a variety of human tissues.

Preoperative evaluation of the curative resectability of gastric cancer by abdominal computed tomography and ultrasonography: a prospective comparison study

OBJECTIVES

We compared the ability of preoperative abdominal computed tomography (CT) with that of preoperative abdominal ultrasonography (US) in predicting the extent of tumor growth and the curative resectability of gastric cancer.

METHODS

Abdominal CT and US were done in 95 patients with gastric adeno-carcinoma. The radiologic findings were prospectively compared with surgical and pathologic findings.

RESULTS

The sensitivities of abdominal CT and US in detecting the perigastric lymph node involvement were 26.6% and 20%, respectively. The sensitivity of abdominal CT in predicting the pancreatic invasion (60%) was better than that of abdominal US (20%). However, there were 6 false positive diagnosis of pancreatic invasion by abdominal CT; in contrast, there was no false positive diagnosis of pancreatic invasion by abdominal US. Of 95 patients who underwent surgical exploration, 14 were found to have unresectable tumors because of extragastric organ involvement and distant metastases. Abdominal CT falsely predicted 8 of 14 cases in which curative gastric resection was impossible as resectable. Moreover, abdominal CT falsely predicted 5 of 81 cases in which curative gastric resection was possible as unresectable. Abdominal US falsely predicted 12 of 14 cases in which curative surgery was impossible as resectable.

CONCLUSION

Preoperative abdominal Ct and US did not accurately predict the tumor extent and the curative resectability of the gastric cancer. Especially, abdominal CT finding of pancreatic invasion by gastric cancer should not be a contraindication for surgical exploration.

Cellular uptake and antitumor activity of the new anthracycline analog DA-125 in human cancer cell lines

To predict the clinical usefulness of DA-125, a newly developed doxorubicin analog, we compared its antitumor activity against 20 different human cancer cell lines with that of doxorubicin using the MTT in vitro chemosensitivity test. We also measured and compared the cellular uptake of this drug and doxorubicin in two cancer cell lines and their doxorubicin-resistant sublines. In the MTT test, DA-125 showed lower IC50 values than doxorubicin for 14 of 20 cell lines. DA-125 was more potent than doxorubicin for hepatocellular cancer cells with high mdr 1 expression. Among cancer cells from the stomach and colon, DA-125 was more potent than doxorubicin in 12 of 14 cell lines. We also investigated the cross-resistance of this drug with doxorubicin using four doxorubicin-resistant cancer cell sublines. Except in one cell line, there was very low cross-resistance. Cellular drug-uptake experiments were performed for two gastric cancer cell lines and their doxorubicin-resistant sublines. In this experiment, DA-125 was found to be very rapidly and completely converted to its active metabolite, M1, in the culture media. After this conversion, M1 was incorporated into these cancer cells more rapidly and reached higher intracellular concentrations than doxorubicin, suggesting that DA-125 (as M1) could achieve earlier and higher levels of intracellular accumulation than doxorubicin in its target tissues from the bloodstream. As a possible alternative antineoplastic agent to doxorubicin, DA-125 awaits further evaluation for its antitumor activity and toxicity.

Mutation of p53 gene in hepatocellular carcinoma cell lines with HBX DNA

It has been known that the incidence of p53 mutation is very rare in HBX-positive primary human hepatocellular carcinoma (HCC) tissues. The frequency of p53 mutation, however, in established cell lines with integrated HBV DNA and/or HBX has not been well studied. To know p53 mutational frequency, and to investigate whether the presence of HBX DNA sequence correlates with the absence of p53 mutation in the established HCC cell lines, we studied the p53 mutation and the presence of HBX sequence in 12 recently characterized HCC cell lines. As a result, all 12 (100%) lines showed mutation in the p53 gene. Three (25%) cell lines had transversion of codon 215 while no mutation of codon 249 was found. In contrast with previous reports, although HBX DNA was present in 11 cell lines, p53 mutation had occurred, indicating that the presence of HBX viral DNA does not correlate with a lack of p53 mutation in established HCC cell lines. Our results suggest that the frequency of p53 mutation is extremely high even in HBX DNA positive HCC cell lines.

Increased expression of the insulin-like growth factor I (IGF-I) receptor gene in hepatocellular carcinoma cell lines: implications of IGF-I receptor gene activation by hepatitis B virus X gene product

Hepatitis B virus infection is associated with acute and chronic liver disease and the development of hepatocellular carcinoma (hcc). Several lines of evidence have suggested that hepatitis B virus X protein (HBx), which is a transcriptional trans-activator, plays a role in the process of liver carcinogenesis. We have investigated the expression of insulin-like growth factor I (IGF-I) receptor in human hepatocellular carcinoma cell lines using SNU368 cells containing HBx and SNU387 cells, which lack HBx gene transcript (J-G. Park et al., Int. J. Cancer, 62: 276-282, 1995), in an attempt to understand its possible relationship to the HBx-induced hcc. The binding of 125I-labeled IGF-I to the SNU368 cells was 5-fold higher than that of SNU387 cells. The Scatchard analysis of the binding data revealed a single class binding site for IGF-I with Kd of 7.6 and 8.8 nM and maximum binding capacities of 169 and 33 fmol/10(5) cells, respectively. Therefore, the difference observed in 125I-labeled IGF-I binding between SNU368 and SNU387 cells was due to an increase in the number of IGF-I binding sites with no change in affinity for the IGF-I receptor. An enhanced level of IGF-I receptors in SNU368 cells was also observed by fluorescence-activated cell sorting analysis using a monoclonal antibody against human IGF-I receptor, alpha IR3. The level of IGF-I receptor RNA and the basal IGF-I receptor gene promoter activity in SNU368 cells were 5 and 10 times higher than those observed in SNU387 cells, respectively. To substantiate further that HBx could transactivate the expression of the endogenous IGF-I receptor gene, Hep G2 cells were transiently transfected with a HBx expression vector. The transfection of Hep G2 cells with an HBx expression vector resulted in increased levels of IGF-I receptor RNA, promoter activity, and 125I-labeled IGF-I binding by 2.6-, 2.8-, and 2-fold, respectively. As a result of higher levels of IGF-I receptor, the mitogenic effect of IGFs (IGF-I and IGF-II) on SNU368 cells was 6 times higher than that of SNU387 cells. These results suggest that HBx may play a role in the process of hcc by activating IGF-I receptor gene expression.

The cytotoxicity of psoralidin from Psoralea corylifolia

A cytotoxic coumestan derivative, psoralidin (1), was isolated from the seed of Psoralea corylifolia. The IC50 values of 1 against SNU-1 and SNU-16 carcinoma cell lines were 53 and 203 micrograms/ml, respectively, indicating cytotoxic activity against stomach carcinoma cell lines.

Abrogation of the Fc gamma receptor IIA-mediated phagocytic signal by stem-loop Syk antisense oligonucleotides

The role of Syk kinase in Fc gamma receptor (Fc gamma R) IIA-mediated phagocytosis was examined with two forms of antisense oligodeoxynucleotides (ODNs) designed to hybridize to human Syk mRNA. Monocytes were incubated with linear and stem-loop antisense ODNs targeted to Syk mRNA. When complexed with cationic liposomes, stem-loop Syk antisense ODN with phosphorothioate modification exhibited stability in fetal bovine and human serum. The stem-loop Syk antisense ODN at a concentration of 0.2 microM inhibited Fc gamma RIIA-mediated phagocytosis by 90% and completely eliminated Syk mRNA and protein in monocytes, whereas scrambled-control ODNs had no effect. The Syk antisense ODNs did not change beta-actin mRNA levels and Fc gamma RII cell-surface expression. In addition, stem-loop Syk antisense ODN inhibited Fc gamma RI and Fc gamma RIIIA-mediated phagocytosis. These data indicate the efficacy of stem-loop Syk antisense ODN for targeting and degrading Syk mRNA and protein and the importance of Syk kinase in Fc gamma receptor-mediated phagocytosis. Immunoblotting assay demonstrated that Fc gamma RII tyrosine phosphorylation after Fc gamma RII cross-linking did not change in the absence of Syk protein. These results indicate that Syk kinase is required for Fc gamma RIIA-mediated phagocytic signaling and that Fc gamma RII cross-linking leads to tyrosine phosphorylation of Fc gamma RII independent of Syk kinase.

Experimental study of self-expandable metallic inferior vena caval stent crossing the renal vein in rabbits. Radiologic-pathologic correlation

RATIONALE AND OBJECTIVES

The authors evaluate in the rabbit the radiologic-pathologic changes of the inferior vena cava and the renal vein and the functional changes of the kidneys after placement of a self-expandable metallic stent in the inferior vena cava where the renal vein empties.

METHODS

One self-expandable metallic stent was placed in the inferior vena cava in each of 12 rabbits; the rabbits were divided into four groups of three rabbits each. The inferior vena cava and renal vein were examined angiographically and pathologically at intervals of 1 week, 2 weeks, 1 month, and 3 months. Vena cavography was performed to evaluate changes in the inferior vena cava before and after stenting. Laboratory tests were performed to determine blood urea nitrogen and creatinine levels, and radioisotope renal scans were performed to evaluate possible changes in renal function before and after stenting.

RESULTS

No stent migration was noted in 11 of 12 rabbits; however, migration of the stent to the subdiaphragmatic level was noted in 1 rabbit. All stents were patent angiographically. Statistical analysis showed no significant change in renal function after stenting (blood urea nitrogen, P = 0.9; creatinine P = 0.5). In addition, radioisotope scans revealed no abnormal findings in perfusion and excretion. Pathologic examination of both kidneys showed no abnormal findings. Neointimal proliferation over the stent was first noted at 1 week after the stent was placed, was most prominent at 1 month, and regressed substantially by 3 months.

CONCLUSIONS

The self-expandable metallic stent was relatively well adapted to the inferior vena cava. Renal function was not affected by the inferior vena cava stent, which crossed the orifice of renal vein.

Aspergilloma within intralobar pulmonary sequestration

We report a case of pulmonary aspergilloma which developed within intralobar pulmonary sequestration.

Biology of colorectal and gastric cancer cell lines

Cell lines established from the human colorectal and gastric cancers may provide very useful tools to the study of the disease and to develop and test new therapeutic approaches, and a large bank of well-characterized cell lines should reflect the diversity of tumor phenotypes and provide adequate models for the study of tumor heterogeneity. Colorectal lines are relatively easy to establish, while gastric cancer cell lines remain extremely difficult to propagate in long-term culture, and the number of cell lines is very limited. In this paper, we describe the up-to-date results of the characteristics of our nine colorectal cancer cell lines and four gastric cancer cell lines. Based on culture, xenograft, and ultrastructural morphologies, these cell lines could be subtyped into well-differentiated, moderately differentiated, poorly differentiated, and mucinous carcinomas. Basic properties concerning expression and secretion of antigens, neuroendocrine features, receptor binding of various gastrointestinal hormones and neurotransmitters, cytogenetic studies, gene amplification and expression, and chemosensitivity profiles are described. In particular, a greater number of receptors for hormones and neurotransmitters are expressed on human colorectal cancer cell lines compared to gastric cancer cell lines, raising the possibility that gastrointestinal hormones may have a greater autocrine effect on colon cancer cell growth. Despite major differences in the biology of colorectal cancer and gastric cancer as indicated by clinical studies, the multiple properties that we examined reveals marked similarities between the colorectal and gastric cancer cell lines. However, in vitro chemosensitivity patterns to cytotoxic drugs are very different in colorectal and gastric cell lines. Some of these observations may be due to the relatively low expression of the multidrug-resistance-associated (MDR1) gene in gastric cancer cell lines. In addition, colorectal cancer cell lines express receptors for peptide hormones more frequently.

The molecular dissection of Fc gamma receptor mediated phagocytosis

Because hematopoietic cells express multiple Fc gamma receptor isoforms, the role of the individual Fc gamma receptors in phagocytosis has been difficult to define. Transfection of Fc gamma receptors into COS-1 cells, which lack endogeneous Fc gamma receptors but have phagocytic potential, has proved valuable for the study of individual Fc gamma receptor function. Using this model system, we have established that a single class of human Fc gamma receptor mediates phagocytosis in the absence of other Fc receptors and that isoforms from each Fc gamma receptor class mediate phagocytosis, although the requirements for phagocytosis differ. In investigating the relationship between structure and function for Fc gamma receptor mediated phagocytosis, the importance of the cytoplasmic tyrosines of the receptor or its associated gamma chain has been established. For example, two cytoplasmic YXXL sequences, in a configuration similar to the conserved tyrosine-containing motif found in Ig gene family receptors, are important for phagocytosis by the human Fc gamma receptor, Fc gamma RIIA. Fc gamma RI and Fc gamma RIIIA do not possess cytoplasmic tyrosines but transmit a phagocytic signal through interaction with an associated gamma subunit that contains two YXXL sequences in a conserved motif required for phagocytosis. The human Fc gamma RII isoforms Fc gamma RIIB1 and Fc gamma RIIB2 do not induce phagocytosis and have only a single YXXL sequence. Cross-linking the phagocytic Fc gamma receptors induces tyrosine phosphorylation of either Fc gamma RIIA or the gamma chain, and treatment with tyrosine kinase inhibitors reduces both phagocytosis and phosphorylation of the receptor tyrosine residues. Activation of protein tyrosine kinases follows Fc gamma receptor engagement of IgG-coated cells. The data indicate that coexpression of the protein tyrosine kinase Syk, which is associated with the gamma chain in monocytes/macrophages, is important for phagocytosis mediated by Fc gamma RI and Fc gamma RIIIA. Furthermore, phosphatidylinositol-3 kinase is required for phagocytosis mediated by Fc gamma RIIA as well as for phagocytosis mediated by Fc gamma RI/gamma and Rc gamma RIIIA/gamma.

Effects of corticosteroid and chlorambucil on multiple pulmonary artery aneurysms in Behcet's syndrome. A case report

A patient with Behcet's syndrome in whom multiple pulmonary artery aneurysms were completely resolved after a combined treatment with corticosteroid and chlorambucil is reported.

Determinants of the phagocytic signal mediated by the type IIIA Fc gamma receptor, Fc gamma RIIIA: sequence requirements and interaction with protein-tyrosine kinases

The Fc gamma receptor-associated gamma and zeta subunits contain a conserved cytoplasmic motif, termed the immunoglobulin gene tyrosine activation motif, which contains a pair of YXXL sequences. The tyrosine residues within these YXXL sequences have been shown to be required for transduction of a phagocytic signal. We have previously reported that the gamma subunit of the type IIIA Fc gamma receptor (Fc gamma RIIIA) is approximately 6 times more efficient in mediating phagocytosis than the zeta subunit of Fc gamma RIIIA. By exchanging regions of the cytoplasmic domains of the homologous gamma and zeta chains, we observed that the cytoplasmic area of the gamma chain bearing a pair of the conserved YXXL sequences is important in phagocytic signaling. Further specificity of phagocytic signaling is largely determined by the two internal XX amino acids in the YXXL sequences. In contrast, the flanking amino acids of the YXXL sequences including the seven intervening amino acids between the two YXXL sequences do not significantly affect the phagocytic signal. Furthermore, the protein-tyrosine kinase Syk, but not the related kinase ZAP-70, stimulated Fc gamma RIIIA-mediated phagocytosis. ZAP-70, however, increased phagocytosis when coexpressed with the Src family kinase Fyn. These data demonstrate the importance of the two specific amino acids within the gamma subunit YXXL cytoplasmic sequences in phagocytic signaling and explain the difference in phagocytic efficiency of the gamma and zeta chains. These results indicate the importance of Syk in Fc gamma RIIIA-mediated phagocytosis and demonstrate that ZAP-70 and syk differ in their requirement for a Src-related kinase in signal transduction.

Characterization of cell lines established from human hepatocellular carcinoma

We characterized 8 human hepatocellular-carcinoma cell lines established from the primary tumors of Korean patients. All lines showed substrate adherence and one line from anaplastic tumor also grew as floating aggregates. Most cultured cells maintained many morphological characteristics of the original tumors from which they were derived. Doubling times varied from 34 to 72 hr. All lines showed relatively high viability and were not contaminated with Mycoplasma or bacteria. All lines showed aneuploidy and were proven to be unique by DNA fingerprinting analysis. Hepatitis-B-virus (HBV) DNA was integrated in the genomes of all lines. Two of the cell lines (SNU-354, SNU-368) showed expression of HBV and HBVx (HBx) transcripts. SNU-354 strongly expressed albumin, and SNU-368 expressed transferrin and insulin-like growth factor II. No lines produced alpha-fetoprotein at the RNA and protein level. These cell lines represent useful tools for in vitro studies related to hepatocellular carcinoma.

Overexpression of phospholipase C-gamma 1 in colorectal carcinomas is associated with overexpression of factors that bind its promoter

The 5'-upstream sequence of the phospholipase C-gamma 1 (PLC-gamma 1) gene contains several transcriptional regulatory regions. We have studied one of the regions (-551 to -480, named GPE1) which exhibits a strong positive regulatory activity. GPE1 stimulated the transcription when fused to heterologous TATA element in an orientation-dependent manner. The region between -536 and -470 was identified as the protein binding site in GPE1 by the DNase I footprinting method. Electrophoretic mobility shift assays with several competitors revealed three protein binding sites in this region, designated as GES1, GES2, and GES3. The binding sites were -535 GGAGGGGGCG -524, -512 TGTCACTCA -504, and -491 CAATCCA -485, respectively. Mutational analyses suggested that GPE1 binding proteins cooperate with each other to activate the transcription of the PLC-gamma 1 gene. Additionally, immunoblot analyses revealed that the level of PLC-gamma 1 expression was considerably higher in 9 of 11 colorectal carcinomas than in adjacent normal colorectal tissues. In 7 of 9 cases of colorectal carcinomas which express higher level of PLC-gamma 1, the DNA binding activities to GES1, GES2, and GES3 sites also increased when compared with normal tissues. These results suggest that the GPE1 binding proteins might be attributed to the elevated expression of PLC-gamma 1 in colorectal carcinomas and may play important roles in proliferation of colorectal carcinoma cells.

Induction of phagocytosis by a protein tyrosine kinase

The transmission of extracellular signals to cellular targets by many noncatalytic surface receptors is dependent on interaction between cytoplasmic protein tyrosine kinases (PTKs) and tyrosine-containing sequences in the cytoplasmic domain of the receptor or an associated subunit. Isoforms of each of the three classes of the noncatalytic Fc gamma receptors, Fc gamma RI, Fc gamma RII, and Fc gamma RIII, are able to transmit a phagocytic signal in transfected COS-1 cells. Both Fc gamma RI and Fc gamma RIIIA require the gamma subunit for this signaling event. The protein tyrosine kinase Syk dramatically enhances phagocytosis mediated by both these receptors and increases the number of cells able to mediate phagocytosis. Two gamma chain cytoplasmic YXXL sequences are required for this effect. The action of Syk is less pronounced on the phagocytic Fc gamma RII receptor, Fc gamma RIIA, which does not require the gamma chain for phagocytosis. However, Syk allows phagocytosis by the nonphagocytic Fc gamma RII receptor Fc gamma RIIB2, which contains only a single YXXL sequence, when an additional tyrosine-containing sequence, YMTL, is introduced. These studies indicate that the efficiency of phagocytosis is markedly enhanced by the presence of a specific protein tyrosine kinase.

Structure/function relationships of Fc gamma receptors in phagocytosis

An important function of Fc gamma receptors is the ingestion or phagocytosis of IgG sensitized cells. It has been difficult to clearly define the individual function of each receptor in phagocytosis because hematopoietic cells express multiple Fc gamma receptor isoforms. To examine this issue, an in-vitro model system in COS-1 cells has been developed. When transfected with an appropriate Fc gamma receptor, COS-1 cells which lack endogeneous Fc receptors, ingest IgG-sensitized cells. Using this model, a single class of human Fc gamma receptor in the absence of other Fc receptors was observed to mediate phagocytosis. Furthermore, isoforms from each Fc gamma receptor class can mediate phagocytosis although the requirements for phagocytosis differ. Investigation of the relationship between structure and function for Fc receptor-mediated phagocytosis established the importance of the cytoplasmic tyrosines of the receptor or its associated gamma chains. For example, two cytoplasmic YXXL sequences, in a configuration similar to the conserved tyrosine containing motif found in immunoglobulin gene family receptors, are important for phagocytosis by the human Fc gamma receptor, Fc gamma RIIA. Fc gamma RI and Fc gamma RIIIA do not possess cytoplasmic tyrosines, but transmit a phagocytic signal through interaction with an associated gamma-subunit which contains two YXXL sequences in a conserved motif required for phagocytosis. The human Fc gamma RII isoforms, Fc gamma RIIB2, do not induce phagocytosis and have only a single YXXL sequence. Crosslinking of the phagocytic Fc gamma receptors induces tyrosine phosphorylation of either Fc gamma RIIA or the gamma chain and treatment with tyrosine kinase inhibitors reduces both phagocytosis and phosphorylation of the receptor tyrosine residues. The protein tyrosine kinase Syk, which is associated with the gamma chain in monocytes/macrophages, dramatically enhances phagocytosis mediated by Fc gamma RI and Fc gamma RIIIA and also induces non-phagocytic Fc gamma RI or Fc gamma RIIIA expressing cells to acquire phagocytic capability.

Genomic structure of human mismatch repair gene, hMLH1, and its mutation analysis in patients with hereditary non-polyposis colorectal cancer (HNPCC)

Mutation of hMLH1, a gene involved in DNA mismatch repair, is responsible for some families carrying the hereditary non-polypotic colorectal cancer (HNPCC) syndrome. To establish a basis for presymptomatic diagnosis of HNPCC patients who carry germline mutations in this gene, we determined the exon-intron organization of hMLH1. The results indicated that hMLH1 consists of 19 coding exons spanning approximately 100 kb, and that exons 1-7 contain a region that is highly conserved in the MLH1 and PMS1 genes of yeast. We used PCR-SSCP analysis and DNA sequencing to examine the entire coding region of the MLH1 gene in DNAs of 34 unrelated cancer patients who belong to HNPCC pedigrees. Germline mutations were detectable in eight (24%) of these patients; four of them were missense mutations, one had occurred in an intron where it would affect splicing, and the remaining three were frameshift mutations resulting in truncation of the gene product downstream of the mutation site.

Adult Hirschsprung's disease. Results of the Duhamel's procedure

Eleven patients with adult Hirschsprung's disease were treated at Seoul National University Hospital (SNUH, 8 cases) and Chosun University Hospital (CUH, 3 cases) between 1985 and 1992. Of the 11 patients, seven were male. The age of the patients ranged from 11 to 30 years, and all presented with chronic constipation and recurrent faecal impactions that required periodic enemas and laxatives. The Duhamel's operation, as a single or staged procedure, was performed in all patients. Levels of aganglionosis in 9 patients were confined to the rectosigmoid colon (82%). There were three major post-operative complications. Two patients developed fistula-in-ano at the anastomotic site, and one patient developed ileus. However, these complications resolved with conservative management. The longterm results were excellent except for one patient who developed impotence. The mean frequency of bowel movements was usually once or twice a day without the aid of other treatments. Our results indicate that Duhamel's operation is a highly acceptable procedure in the management of adult Hirschsprung's disease.

Molecular dissection of Fc gamma receptor-mediated phagocytosis

Using an experimental model in COS-1 cells, we have examined the structural requirements for phagocytosis of IgG-sensitized cells by Fc gamma receptors. We have established that isoforms of each of the 3 classes of the Fc gamma receptors, Fc gamma RI, Fc gamma RII and Fc gamma RIII, are able to transmit a phagocytic signal in the absence of the other receptor class. Fc gamma I and Rc gamma RIIIA require a gamma-subunit for this signaling event, but Fc gamma RIIA does not. Fc gamma RIIA and the gamma-subunit associated with Fc gamma RI and Fc gamma RIIIA contain 2 copies of a conserved tyrosine-containing cytoplasmic sequence, YXXL. This sequence is important for phagocytosis and is phosphorylated on tyrosine after receptor ligation. The Fc gamma receptors Fc gamma RIIB1 and Fc gamma RIIB2 which contain only 1 copy of the YXXL cytoplasmic sequence do not include the phagocytosis of IgG-coated cells. Thus, the Fc gamma receptor isoforms differ in their ability to transmit a phagocytic signal. Structure/function studies also indicate that the Fc gamma receptors which induce phagocytosis differ in their requirements for phagocytic signaling.

CpG island promoter region methylation patterns of the inactive-X-chromosome hypoxanthine phosphoribosyltransferase (Hprt) gene

Inactive-X-chromosome genes in mammalian females have methylated CpG islands. We have questioned whether there are variable levels of cytosine methylation at different CpG sites within the island that might indicate the presence of primary sites of methylation which may be critical for the maintenance of gene repression and candidate sites for the initiation of inactivation. To address these questions, we have analyzed the methylation patterns of 32 CpG sites of the X-linked hypoxanthine phosphoribosyltransferase (Hprt) gene on the active and inactive X chromosomes of mouse tissues and cell lines, using genomic sequencing of bisulfite-treated genomic DNA. Cytosine is deaminated by bisulfite, but methylcytosine is not affected. Cell lines that were heterozygous for the Hprt deletion mutation (Hprtb-m3) and a functional Hprt allele were selected with 6-thioguanine. The resulting cell populations uniformly carry the intact Hprt allele on the inactive X chromosome. The methylation of these CpG sites was determined either by the direct sequence analysis of bisulfite-treated and amplified DNA or by the sequence analysis of clones derived from the amplified DNA. No CpG methylation was detected on the active Hprt genes from either males or the active X chromosome of females. On average, 22 CpGs were methylated in the other 50% of female DNA, and the level of methylation at individual sites varied from 42 to 100%. Analysis of the inactive Hprt gene in two cell lines showed that averages of 14 and 18 CpGs were methylated and that the frequency of methylation at 32 individual sites ranged from 3 to 100%. The highest frequency of methylation in cell lines coincided with the sequences flanking transcription initiation sites. These results suggest that methylation patterns are heterogeneous within a tissue and even in clonal cell populations and that specific subsets of CpG sites sustain high methylation frequencies which may be critical for the maintenance of X-chromosome inactivation. The bisulfite method identified which CpG sites were methylated on the inactive X chromosome, and it provided a quantitative estimate of the frequency of methylation of these sites in genomic DNA.

Os acromiale associated with rotator cuff impingement: MR imaging of the shoulder

PURPOSE

To evaluate the magnetic resonance (MR) imaging findings of os acromiale in rotator cuff disease.

MATERIALS AND METHODS

Retrospective analysis was performed of 10 shoulder MR studies of 10 patients older than 25 years with os acromiale. The authors subdivided these patients into three types on the basis of seven possible configurations.

RESULTS

Eight of the 10 patients with os acromiale showed failure of fusion between the mesoacromion and meta-acromion (type A), one between the preacromion and mesoacromion (type B), and one between the meta-acromion and basiacromion (type C). Osteophytic lipping was seen at the margins of the acromial gap in nine cases. The os acromiale could be detected on the oblique sagittal image, oblique coronal image, or both, and in each case, there was a lesion in the supraspinatus tendon: tendinitis in four patients and tendon tear in six.

CONCLUSION

Os acromiale can be an important cause of rotator cuff impingement and can be detected with routine MR imaging of the shoulder.

Genetic changes in the transforming growth factor beta (TGF-beta) type II receptor gene in human gastric cancer cells: correlation with sensitivity to growth inhibition by TGF-beta

We have found several genetic changes in the TGF-beta-type II receptor gene in human gastric cancer cell lines resistant to the growth inhibitory effect of TGF-beta. Southern blot analysis showed deletion of the type II receptor gene in two of eight cell lines and amplification in another two lines. The single cell line we studied that is sensitive to growth inhibition by TGF-beta showed no structural abnormalities of the type II receptor gene. Some of the gastric cancer cells resistant to the growth inhibitory effect of TGF-beta express either truncated or no detectable TGF-beta type II receptor mRNAs, whereas the one that retains responsiveness to the growth inhibitory effect of TGF-beta expresses a full-size type II receptor mRNA. Immunoprecipitation followed by Western blot analysis showed parallel changes in TGF-beta type II receptor expression. Our results suggest that one of the possible mechanisms of escape from autocrine or paracrine growth control by TGF-beta during carcinogenesis could involve genetic changes in the TGF-beta type II receptor gene itself or altered expression of its mRNA.

Presymptomatic diagnosis of familial adenomatous polyposis coli

Familial adenomatous polyposis (FAP), an autosomal dominant inherited disease, confers a high risk of colon cancer, and recently the gene responsible for FAP, termed adenomatous polyposis coli (APC) gene, was identified and fully characterized.

PURPOSE

For the presymptomatic diagnosis of FAP, we have performed linkage studies using two polymorphic systems close to or at the APC locus; cytosine-adenine dinucleotide repeat length polymorphism and restriction endonuclease RsaI site polymorphism.

METHODS AND RESULTS

Based on the two polymorphic systems, we have determined the haplotype at the APC locus in 23 individuals of two Korean families with FAP. From these haplotypes of individuals, we could make the diagnosis, whether affected or unaffected, in 74 percent of 31 at-risk persons. To decrease the chance of misdiagnosis caused by recombinant events, the use of haplotypes was better than using one polymorphic system. In addition to polymorphic analysis, we have also searched germline mutations of the APC gene in eight individuals (26 percent of all 31 at risk persons) of another two FAP families which could not be diagnosed definitely by linkage analysis. A 5 base-pairs deletion at codon 1309 was detected in one of the families, and a 5 base-pairs deletion at codon 1185 was also identified in another family by using a ribonuclease protection assay followed by DNA sequencing. From these results, we could diagnose FAP with 100 percent accuracy.

CONCLUSION

Linkage studies by the RsaI site polymorphism and cytosine-adenine repeat length polymorphism as well as the polymerase chain reaction-based sequencing method provide accurate and efficient tools for presymptomatic diagnosis of FAP in their families.

Synthesis and antitumor activity of a series of [2-substituted-4,5-bis(aminomethyl)-1,3-dioxolane]platinum(II) complexes

The synthesis, physical properties, antitumor activity, structure-activity relationships, and nephrotoxicity of a series of [2-substituted-4,5-bis(aminomethyl)-1,3-dioxolane]platinum(II) complexes are described. The 42 platinum(II) complexes having a seven-membered ring structure in this series have been prepared and characterized by 1H NMR, 13C NMR, IR, FAB-MS, and elemental analysis. All members of the series were designed to have a 1,3-dioxolane ring moiety in their carrier ligands to increase water solubility. The solubility of platinum complexes was related to the nature of leaving ligands and 2-substituents in the 4,5-bis(aminomethyl)-1,3-dioxolane carrier ligands. In general, compounds having two different R1 and R2 substituents in the 4,5-bis(aminomethyl)-1,3-dioxolane moiety were more water-soluble than those having the same substituents. Most members of this series showed the excellent antitumor activity against murine L1210 leukemia cells transplanted in mice and were superior to cisplatin and carboplatin. The (4R,5R)-stereoisomer 1a-h exhibited the higher antitumor activity than the corresponding (4S,5S)-stereoisomer 2a-h in the (1,1-cyclobutanedicarboxylato)platinum(II) complexes. The (glycolato)-platinum(II) complexes were highly cytotoxic toward four human stomach cancer cell lines, SNU-1, SNU-5, SNU-16, and NCI-N87, and among them, complexes 3d-g were even more cytotoxic than cisplatin. The (malonato)platinum(II) complex 1m and the (glycolato)platinum(II) complexes 3d-g were selected for further studies based on the greater in vivo and in vitro antitumor activity and desirable physical properties. The complexes 3e-g were almost equally cytotoxic to cisplatin toward human stomach cancer cell lines, KATO-III and MKN-45, and a human non-small cell lung cancer cell line, PC14. In contrast with cisplatin and carboplatin, five complexes selected significantly increased in life span in mice transplanted with cisplatin-resistant L1210 cells. Nephrotoxicity studies in ICR mice indicated that serum BUN and creatinine levels were not elevated when five complexes were given at a dose equal to 1.5 times the optimal dose determined in the in vivo L1210 screening system.

MDR1 gene expression: its effect on drug resistance to doxorubicin in human hepatocellular carcinoma cell lines

BACKGROUND

Hepatic tumors are resistant to many chemotherapeutic agents. Although elevated MDR1 (also known as PGY1) gene expression has been shown in such tumors, no direct association has been established between the gene expression and multidrug resistance.

PURPOSE

To evaluate the role of the MDR1 gene in the drug resistance of hepatoma, we tested nine human hepatoma cell lines for their expression of the MDR1 gene.

METHODS

We measured the MDR1 messenger RNA (mRNA) expression by RNA slot-blot analysis and by immunocytochemical staining with a P-glycoprotein-specific monoclonal antibody, MRK16. The in vitro chemosensitivity of these cell lines to fluorouracil, doxorubicin, mitomycin C, cisplatin, and etoposide (VP-16) was determined using the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) colorimetric assay. For doxorubicin cytotoxicity, we also tested the potentiating effect of several multidrug resistance-reversing agents.

RESULTS

Slot-blot analysis and immunocytochemistry showed that two cell lines expressed high levels of MDR1 mRNA, one expressed an intermediate level, and all others were low expressors. The MTT assay results showed that all cell lines tested were generally resistant to chemotherapeutic agents. The assay area under the curve (AUC) was within a clinically achievable range only for VP-16 in one of nine cell lines. When the IC50 values were compared among the cell lines, the results revealed a close association with the MDR1 gene expression only for doxorubicin resistance. Verapamil and quinidine lowered the IC50 values of doxorubicin for MDR1-positive cell lines. The lowered assay AUC levels for both reversing agents, however, were still higher than the clinically achievable range.

CONCLUSION

These results indicate that the MDR1 gene probably has a role in doxorubicin resistance in hepatocellular carcinoma and that the resistance can be overcome by some multidrug resistance-reversing agents.

IMPLICATIONS

Some widely used anticancer agents might be ineffective for treating hepatocellular carcinoma in clinical situations even when combined with reversing agents.

Overexpression of phospholipase C-gamma 1 in familial adenomatous polyposis

Phosphoinositide-specific phospholipase C (PLC) isozymes occupy a central role in the signal transduction system by regulating various cellular processes including proliferation and differentiation. In the present study, we examined the contents of PLCs in colorectal adenomas, carcinomas, and normal mucosa obtained from 4 familial adenomatous polyposis patients to find out whether this enzyme plays any role in the pathogenesis of adenomas and/or carcinomas in familial adenomatous polyposis. Radioimmunoassay and immunoblot analysis revealed that in contrast to little difference in PLC-beta 1 and PLC-delta 1 content, a considerably higher level of PLC-gamma 1 was detected in 3 of 4 cases for adenoma and in all cases for carcinoma as compared to normal mucosa. The level of PLC-gamma 1 expression increased from normal mucosa to adenoma, and finally to carcinoma progressively. Immunohistochemical findings also confirmed this observation. Likewise, activity of PLC-gamma 1 was considerably higher in adenomas and carcinomas than in normal mucosa. These results suggest that PLC-gamma 1-mediated signal transduction may play a significant role in the progression of colorectal tumors in patients with familial adenomatous polyposis.

Elevated content of phospholipase C-gamma 1 in colorectal cancer tissues

BACKGROUND

Phospholipase C isozymes (PLC) play a role in ligand-mediated signal transduction for cellular activity, such as proliferation and differentiation. However, the biologic significance of their molecules in carcinogenesis or tumor progression is yet to be determined.

METHODS

Using PLC isozyme-specific antibodies, the relative content of PLC in human colorectal carcinomas and in normal colonic mucosa was examined.

RESULTS

Immunoreactive analysis revealed considerably higher levels of PLC-gamma 1 protein in 15 of 17 colorectal carcinomas and little difference in PLC-beta 1 or PLC-gamma 1 content compared with normal colorectal tissues. By radioimmunoassay and Western blotting, PLC-gamma 1 showed three-fold to fourfold more expression in carcinomas than that in normal tissues.

CONCLUSION

Although factors that might influence the level of PLC-gamma 1 expression in colorectal carcinomas still remain obscure, the fact that most colorectal carcinomas display elevated levels of PLC-gamma 1 expression implies that PLC-gamma 1 may play an important role in proliferation of colorectal carcinoma cells.

Genetic instability in pancreatic cancer and poorly differentiated type of gastric cancer

To examine genetic instability during carcinogenesis, we screened 171 carcinomas of the breast, liver, proximal colon, stomach, pancreas, uterine cervix, and ovary for replication error at four microsatellite marker loci on chromosome 2, 3, and 17. A significantly high incidence of genetic instability was observed in pancreatic (6 of 9 tumors) and gastric cancers (22 of 57 cases). In other types of carcinoma, the incidence of replication error-positive cases was relatively low (3-16%). Among gastric carcinomas, significantly more replication error-positive cases were observed in the poorly differentiated types (16 of 25 cases) than in well differentiated types (3 of 18) (P = 0.0023 by Fisher's exact test). Our results suggested that genetic instability is likely to play an important role in development of pancreatic and gastric cancers, particularly poorly differentiated adenocarcinomas.

Conserved cytoplasmic tyrosine residues of the gamma subunit are required for a phagocytic signal mediated by Fc gamma RIIIA

Fc receptors for immunoglobulins are found on many cells and are important in host defense. We transfected Fc gamma RIIIA, present on macrophages and natural killer (NK) cells, into COS-1 cells to study its role in phagocytosis and calcium mobilization in the absence of other Fc gamma receptors. Human Fc gamma RIIIA-alpha (CD16) was cotransfected with its associated chains, either Fc gamma RIIIA gamma or zeta. Both gamma and zeta were observed to induce a phagocytic signal, but gamma was at least sixfold more effective than zeta. Conservative substitution by phenylalanine of either one of the two cytoplasmic tyrosine residues in the gamma chain resulted in markedly diminished phagocytosis and calcium mobilization. Tyrphostin 23, an inhibitor of tyrosine kinases, reversibly inhibited phagocytosis. Further, in vitro kinase assays with the wild type and mutant gamma chains demonstrated that the wild type gamma chain, but not the mutant gamma chains, is phosphorylated. These results suggest that the cytoplasmic tyrosine residues and tyrosine phosphorylation are required for Fc gamma RIIIA to mediate two signal transduction events: phagocytosis and calcium mobilization.

In the absence of other Fc receptors, Fc gamma RIIIA transmits a phagocytic signal that requires the cytoplasmic domain of its gamma subunit

The transmembrane isoform of Fc gamma RIII, Fc gamma RIIIA, is found on NK cells, cultured monocytes, and tissue macrophages in association with a dimer of an accessory subunit, either gamma or zeta. Functions of individual Fc receptors have been difficult to analyze due to coexpression of the receptors on hematopoietic cells and permanent cell lines expressing Fc receptors. cDNAs for the alpha and gamma subunits of Fc gamma RIIIA were cotransfected into COS-1 cells, which lack endogenous Fc receptors, to evaluate receptor-mediated phagocytosis and changes in [Ca2+]i. Transfectants both bound and phagocytosed IgG-sensitized erythrocytes and, following activation of Fc gamma RIIIA, increased [Ca2+]i. The gamma subunit was essential both for the surface expression of the receptor and for transduction of the phagocytic signal. Truncation of the gamma subunit cytoplasmic domain (amino acids 65-80) eliminated phagocytic function. Phorbol ester inhibited phagocytosis in a concentration-dependent manner, but did not affect IgG-sensitized erythrocytes binding, suggesting that a protein kinase C-dependent pathway inhibits phagocytosis. The data indicate that a tyrosine containing cytoplasmic domain within the gamma subunit is required for phagocytosis by Fc gamma RIIIA.

Expression of carcinoembryonic antigen and related genes in lung and gastrointestinal cancers

Carcinoembryonic antigen (CEA), a tumor marker for lung cancers of small cell (SCLC) and non-small cell (NSCLC) types, belongs in a multigene family which includes non-specific cross-reacting antigen (NCA) and biliary glycoprotein 1 (BGP). We used specific cDNA probes and a CEA immunoassay to determine the pattern of expression in normal and malignant lung and gastrointestinal (GI) tissues. Normal lung contained high amounts of NCA and a low concentration of CEA. All 3 genes were expressed discordantly in lung tumors and cell lines. In contrast, all three genes were expressed in most G1 tumor cell lines. In both lung and colorectal cell lines expression of NCA RNA was relatively high, while BGP RNA was relatively low, and the median concentrations of CEA were greater than in corresponding non-malignant tissues. While CEA protein concentrations in lung cell lines were similar to those present in G1 cell lines, the ratio of NCA:CEA RNA was significantly higher in lung cancer lines than in colorectal lines. Thus, NCA constitutes most of the "CEA-like" immunoreactivity previously described in lung cancers. There was excellent concordance between expression of CEA RNA and CEA protein, as well as between concentrations of CEA protein in cell line pellets and supernatant fluids. Of interest, significantly higher rates of CEA expression were present in lung cancers expressing neuroendocrine (NE) markers. The association between CEA expression and NE cell properties is intriguing and may prove to be of clinical interest.

Risk of gastric cancer among Korean familial adenomatous polyposis patients. Report of three cases

Gastric cancer has been recognized as an extracolonic manifestation in patients with familial adenomatous polyposis (FAP). In Korea, gastric cancer is the most common malignant neoplasm. In a recent survey, we collected data from 72 Korean patients with FAP. Among them, three (4.2 percent) were found to have associated gastric cancer. This incidence of gastric cancer in our series is much higher than the previous reports from Japan and other countries. The expected cumulative incidence of gastric cancer among these 72 patients was 0.44, which gives the standardized incidence ratio of 6.9 (95 percent CI, 1.4-20.1). This difference in incidence of gastric cancer was statistically significant (P less than 0.05), which implies that patients with FAP are at significantly higher risk of developing gastric cancer compared with the general population in Korea. These findings confirm an increased risk of gastric cancer in FAP patients, even in a region where gastric cancer is highly prevalent.

Large-scale molecular mapping of human c-myb locus: c-myb proto-oncogene is not involved in 6q- abnormalities of lymphoid tumors

Chromosomal abnormalities in the 6q region have been observed frequently in several T-cell and myeloid leukemias. Interestingly, this region was found to contain three cellular oncogenes, c-myb, c-fyn and c-ros. Several of the tumors that exhibit 6q- abnormalities have also been found to express high levels of c-myb and, in some cases, amplification of the c-myb gene, leading to the suggestion that this gene could lie in proximity to the deletions observed in these tumors. To determine if c-myb gene activation is associated with 6q- abnormalities, we developed a megabase map of the human c-myb locus using pulsed-field gel electrophoresis. We then examined the occurrence of abnormalities near the c-myb gene in several hematopoietic tumor cell lines containing well-characterized 6q- abnormalities. Our results show that no rearrangements or deletions occur within a region of 1.0 Mbp of the c-myb locus in these cell lines. However, several of the cell lines exhibited differential and partial methylation patterns which seem to be prevalent amongst different cell lines.

Effects of buthionine sulfoximine treatment on cellular glutathione levels and cytotoxicities of cisplatin, carboplatin and radiation in human stomach and ovarian cancer cell lines

Chemotherapy failure remains a significant medical problem in the treatment of neoplastic disease and is thought to be due to many different factors including membrane transport, p-glycoprotein in multidrug resistance, glutathione and its related enzymes, topoisomerase II and DNA repair. Glutathione is a major constituent of non-protein thiol and participates in detoxification of chemotherapy and radiation. Thus, glutathione concentration is correlated with sensitivity to alkylating agents and radiation, and increased in resistant cell lines. Buthionine sulfoximine (BSO) is an inhibitor of glutathione biosynthesis and may increase cytotoxicities of alkylating agents, including melphalan and cisplatin, and radiation in sensitive and resistant cell lines. We studied effects on cellular glutathione levels and cytotoxicities of cisplatin, carboplatin and radiation by BSO treatment in human stomach cancer cell line (SNU-1) and ovarian cancer cell line (OVCAR-3). The results were as follow: 1) After BSO treatment of 1 mM and 2 mM for 2 days, the intracellular thiol concentration was depleted to 75.7% and 76.2% in SNU-1, and 74.1% and 63.0% in OVCAR-3, respectively. 2) The intracellular thiol concentration in SNU-1 was depleted to 33.4% after BSO 2 mM for only 2 hours incubation and 71.5% after small amount of BSO (0.02 mM) for 2 days. 3) The recovery of intracellular thiol concentration required more than 3 days after BSO removal. 4) BSO inhibited partially the growth of SNU-1 and OVCAR-3. 5) The cytotoxicities of cisplatin and carboplatin were markedly enhanced both in SNU-1 and OVCAR-3 by BSO treatment. 6) The cytotoxicities of radiation was increased in OVCAR-3 and SNU-1 by BSO treatment. Therefore, it is concluded that BSO can deplete effectively the intracellular thiol concentration and enhance the cytotoxicities of cisplatin, carboplatin and radiation.

Chromogranin-a expression in gastric and colon cancer tissues

We studied the expression of chromogranin A (CgA) in human gastric (n = 17) and colorectal (n = 18) adenocarcinomas by nucleic acid hybridization and immunohistochemical analyses using a specific monoclonal antibody (MAb) to human chromogranin A (CgA). Some corresponding adjacent non-malignant mucosal tissues were also examined.

RESULTS

(1) Northern blotting: of 3 normal gastric mucosas examined, 2 (67%) had an easily detected signal for expression of CgA. Only one of 14 gastric carcinomas (7%) and one of 18 colorectal carcinomas (6%) had easily detected RNA signals. (2) Immunohistochemical staining: all non-malignant samples of gastric and colonic mucosa contained CgA-positive neuroendocrine (NE) cells. Two of 17 (12%) gastric adenocarcinomas, and 3 of 18 (17%) of colorectal adenocarcinomas contained CgA-positive tumor cells. Interestingly, the positive cases detected by immunohistochemistry included both cases detected by Northern blotting. Of the 5 cases detected by immunohistochemistry, 2 gastric cancers and 1 rectal carcinoma contained many diffusely scattered positive cells, occurring singly or in small clusters, while 2 colorectal carcinomas contained only occasional single CgA-positive tumor cells. In one of the positive gastric cases, a well-differentiated adenocarcinoma arising in a tubular adenoma, both the adenomatous and the carcinomatous elements contained positively staining cells. Our specific assays for CgA indicate that (1) a NE cell component, either diffusely scattered or occasional, occurs in about 15% of gastric and colorectal tumors; (2) there is no correlation between the presence of NE cells and degree of tumor differentiation; and (3) because only a minority of the tumor cells in positive cases stain for CgA, immunohistochemistry is a more sensitive method than Northern blotting.

Autonomous proliferation of colon cancer cells that coexpress transforming growth factor alpha and its receptor. Variable effects of receptor-blocking antibody

Four human colon adenocarcinoma cell lines, SNU-C1, SNU-C4, SNU-C5, and NCI-H716, that are capable of proliferating autonomously in serum-free medium containing no added peptide growth factors were identified. All four cell lines show epidermal growth factor (EGF) receptors (EGFRs), express transforming growth factor alpha (TGF-alpha) messenger RNA, and release anti-TGF-alpha-immunoreactive molecules. The blocking anti-EGFR monoclonal antibody (mAb) 225 blocks autonomous proliferation of SNU-C1 and SNU-C4 cells. In both of these cell lines, the inhibitory effect of mAb 225 is reversible by the addition of EGF, TGF-alpha, or conditioned medium from any of the four cell lines. In contrast, autonomous proliferation of SNU-C5 and NCI-H716 cells is not inhibited by mAb 225 and is not affected by exogenous EGF, TGF-alpha, or conditioned medium. Together, these data confirm the previous finding that anti-EGFR antibodies can inhibit the proliferation of some carcinoma cell lines that coexpress TGF-alpha and EGFR. However, here it is shown that the mechanisms of autonomous proliferation of colon carcinoma cell lines are heterogeneous and not always sensitive to antibody disruption of TGF-alpha/EGFR autocrine interactions.

Pattern of growth factor, proto-oncogene and carcinoembryonic antigen gene expression in human colorectal carcinoma cell lines

The aim of the present study was to examine whether the expression of growth factor genes, proto-oncogenes and carcinoembryonic antigen (CEA) gene in human colorectal cancer cell lines was related to their clinicobiological behavior. A significant variability among cell lines was detected for both insulin-like growth factor II and transforming growth factor beta gene message. Detectable levels of c-myc, Her-2, c-myb, K-ras and EGF receptor mRNA were found in most cell lines, whereas only 1/11 and 2/11 cell lines were positive for N-myc and c-sis message, respectively. N-myc expression was limited to a cell line originated from a tumor with neuroendocrine features, while high levels of K-ras message were found only in a cell line derived from a radioresistant tumor. CEA mRNA levels correlated well with the concentration of antigen in each cell line. On the basis of these results, our findings demonstrated that human colorectal cancer cell lines show heterogeneous expression of growth factor and CEA genes and proto-oncogenes; however, with the exception of K-ras, N-myc and CEA, other correlations between gene expression and the clinicobiological characteristics of these cell lines could not be demonstrated.

Occurrence of p53 gene abnormalities in gastric carcinoma tumors and cell lines

We explored the state of the p53 gene in gastric cancer. Using one or more methods, we examined 15 specimens from primary carcinomas (14 tumors, one cell line), five cell lines derived from metastases, and seven paired samples of nonmalignant gastric mucosa. Sequence analyses of complementary DNA containing the entire p53 gene open reading frame demonstrated abnormalities in one of five samples from primary tumors and in all five samples from metastases. The single cell line derived from a primary carcinoma had no abnormality of the gene. The six abnormalities included four point mutations, one base-pair deletion resulting in a frame shift, and a 24 base-pair deletion caused by an intronic point mutation (as determined by sequence analysis of genomic DNA). Four of the six mutations mapped to regions highly conserved among species or involved in simian virus 40 T-antigen binding. Restriction fragment length polymorphism studies confirmed that chromosome 17p allelic deletions occur only in a minority of primary tumors, but that they may occur more frequently in metastases. Northern blotting and ribonuclease protection assays detected only a fraction of the p53 gene abnormalities detected by sequencing. Our findings indicate that mutations of the p53 gene are relatively rare in primary gastric tumors but appear to be relatively frequent in cell lines derived from metastatic lesions. Our results may help in understanding the molecular events associated with progression and metastasis in gastric carcinoma.

Novel DNA sequences at chromosome 10q26 are amplified in human gastric carcinoma cell lines: molecular cloning by competitive DNA reassociation

Molecular cloning of genomic sequences altered in cancer cells is believed to lead to the identification of new genes involved in the initiation and progression of the malignant phenotype. DNA amplification is a frequent molecular alteration in tumor cells, and is a mode of proto-oncogene activation. The cytologic manifestation of this phenomenon is the appearance of chromosomal homogeneously staining regions (HSRs) or double minute bodies (DMs). The gastric carcinoma cell line KATO III is characterized by a large HSR on chromosome 11. In-gel renaturation analysis confirmed the amplification of DNA sequences in this cell line, yet none of 42 proto-oncogenes that we tested is amplified in KATO III DNA. We employed the phenol-enhanced reassociation technique (PERT) to isolate 21 random DNA fragments from the amplified domain, and used 6 of them to further clone some 150 kb from that genomic region. While in situ hybridization performed with some of these sequences indicated that in KATO III they are indeed amplified within the HSR on chromosome 11, somatic cell hybrid analysis and in situ hybridization to normal lymphocyte chromosomes showed that they are derived from chromosome 10, band q26. The same sequences were found to be amplified in another gastric carcinoma cell line, SNU-16, which contains DMs, but were not amplified in other 70 cell lines representing a wide variety of human neoplasms. One of these sequences was highly expressed in both KATO III and SNU-16. Thus, the cloned sequences supply a starting point for identification of novel genes which might be involved in the pathogenesis of gastric cancers, and are located in a relatively unexplored domain of the human genome.