Biomedical subjects

S Imaoka

Publications and source records attributed to S Imaoka.

At least 19 recordsLinked to original sources

PubMed1996

Demonstration of monoclonal origin of human parotid gland pleomorphic adenoma.

BACKGROUND: Parotid gland pleomorphic adenoma is histologically comprised of epithelial and mesenchymal elements. It remains to be established whether this neoplasm arises from epithelial and mesenchymal elements, or solely from the epithelial element. METHODS: In an attempt to resolve this issue, we have conducted clonal analysis on five pleomorphic adenomas. The method for clonal analysis was based on the trinucleotide repeat polymorphism of the x-chromosome-linked androgen receptor gene and on random inactivation of this gene by methylation. The epithelial and mesenchymal elements were obtained separately from the paraffin sections of the pleomorphic adenomas using a microdissection technique and then subjected to clonal analysis. RESULTS: Clonal analysis revealed that both epithelial and mesenchymal elements were monoclonal. In addition, the same allele of the androgen receptor gene was inactivated in both elements in every case. CONCLUSIONS: It is unlikely that the epithelial and mesenchymal elements of different origin happen to inactivate the same allele of the androgen receptor gene in all five tumors. Rather, it is more reasonable to consider that these two elements have a common single cell origin.

Adenoma, Pleomorphic↗

PubMed1996

Clinical features of small hepatocellular carcinomas as assessed by histologic grades.

BACKGROUND: Ninety-seven patients with small hepatocellular carcinomas (HCCs) measuring 3 cm or less in size and three patients with adenomatous hyperplasia who underwent radical hepatic resection were examined in this study. METHODS: The lesions were classified into four groups according to the following histologic grading criteria: group A, adenomatous hyperplasia (n = 3); group B, early HCC (n = 6); group C, well-differentiated HCC (wHCC) (n = 32); and group D, moderately or poorly differentiated HCC (n = 59). The involvement factors that seemed to be important or to characterize the progression of HCC and the survival rates were compared among the four histologic groups. RESULTS: The frequency of patients with tumors larger than 2.0 cm in size and that of patients with 200 or more ng/ml serum alpha-fetoprotein increased with the progression of histologic malignancy. Tumor staining on the angiogram, capsular formation, and extranodular invasion were never seen in groups A and B, but they began to appear in group C and increased remarkably in group D. The 5-year survival rates of the patients in groups B, C, and D were 100%, 60%, and 27%, respectively, and statistically significant differences were seen among them. In comparative evaluation of the group C patients the lesions that showed no tumor staining had no capsule, and those that had no capsule had no extranodular invasion. The 5-year survival rate of patients with wHCC without extranodular invasion (81%) was significantly higher than that of patients with extranodular invasion (35%) (p < 0.05). CONCLUSIONS: It may be recommended to provide the category of wHCC without extranodular invasion for pathologic classification of clinically early HCC (i.e., HCC of high curability).

Aged↗

PubMed1996

Clonal analysis of precancerous lesion of hepatocellular carcinoma.

BACKGROUND & AIMS: It remains to be established whether precancerous lesion (dysplastic nodule) of hepatocellular carcinoma (HCC) is a neoplastic or hyperplastic lesion. Clonal analysis of this lesion was conducted to elucidate this important issue on histogenesis. METHODS: The method for clonal analysis was based on restriction fragment length polymorphism of the X chromosome-linked phosphoglycerokinase gene and on random inactivation of the gene by methylation. Clonal somatic mutations were also analyzed by DNA fingerprinting with two multilocus probes (33.6 and 33.15), and loss of heterozygosity was studied using five single-locus probes (MS1[1p33-p35], MS31[7p22-pter], MS43a[12q24.3-qter], MS8[5q35-qter], and g3[7q36-qter]). RESULTS: Clonal analysis by the phosphoglycerokinase gene-based method showed that all of the five dysplastic nodules and seven HCCs were monoclonal in origin. DNA fingerprinting showed clonal somatic mutations in six of 10 dysplastic nodules and in six of nine HCCs. Loss of heterozygosity was found in one dysplastic nodule (7p22-pter) and two HCCs (1p33-p35 and 12q24.3-qter). CONCLUSIONS: These results confirm monoclonality of HCC and show that hepatic precancerous lesion (dysplastic nodule) is not a hyperplastic but a neoplastic lesion, consisting of monoclonal cells with genetic alterations.

Aged↗

PubMed1996

Detection of gastric cancer micrometastases in lymph nodes by amplification of keratin 19 mRNA with reverse transcriptase-polymerase chain reaction.

A sensitive method for the detection of gastric cancer micrometastases in lymph nodes was developed. The method was based on amplification of keratin 19 mRNA by reverse transcriptase-polymerase chain reaction (RT-PCR). Keratin 19 RT-PCR showed that keratin 19 mRNA was expressed in all 12 gastric cancers, but not in any of 20 normal control lymph nodes, indicating that keratin 19 mRNA is a good target of RT-PCR for the detection of gastric cancer micrometastases in lymph nodes. Serial dilution studies of RNA extracted from gastric cancers against RNA extracted from control lymph nodes demonstrated that the detection sensitivity of the keratin 19 RT-PCR method was one cancer cell in 10(3)-10(5) lymph node cells. Detectability of lymph node metastases was compared between keratin 19 RT-PCR and conventional histological examination, using 100 lymph nodes obtained from 12 gastric cancer patients. Keratin 19 mRNA was detected in all of the seven lymph nodes which were histologically metastasis-positive. Of the 93 lymph nodes which were histologically metastasis-negative, 79 were found not to express keratin 19 mRNA but 14 were found to express keratin 19 mRNA, indicating that these lymph nodes contained micrometastases which could not be detected by histological examination. These results demonstrate that keratin 19 RT-PCR is a more sensitive method than histological examination for the detection of gastric micrometastases in lymph nodes.

Adult↗

PubMed1996

A prospective randomized trial of the preventive effect of pre-operative transcatheter arterial embolization against recurrence of hepatocellular carcinoma.

To clarify whether pre-operative transcatheter arterial embolization (TAE) improves survival after hepatectomy, a prospective randomized comparative study was done. Of a total of 115 registered patients having solitary hepatocellular carcinoma (HCC) 2 to 5 cm in diameter, 18 (15.7%) were excluded after randomization. As a result, 97 patients were chosen as subjects and divided into two groups: hepatectomy with (group A: n=50) and without (group B: n=47) pre-operative TAE. The period of observation of the patients who survived the surgery was between 4.0 and 6.6 years. The randomization appeared to have provided well-balanced groups of patients and the clinico-pathological characteristics of the two groups were quite similar. The necrotic part of the cancerous lesions, as confirmed by operative specimens, amounted to 74.8+/-33.4% (mean +/-SD) in group A and 6.8+/-7.2% in group B (P<0.01). However, the cancer-free survival rates after hepatectomy in both groups showed little difference (39.1+/-7.0 (%+/-SE) and 31.1+/-0.1, respectively). We speculate that TAE is not effective against such HCC accessory lesions as minute intrahepatic metastasis and tumor thrombus and that pre-operative TAE does not improve post-operative survival.

Adult↗

PubMed1996

Metabolism of acetaldehyde to acetate by rat hepatic P-450s: presence of different metabolic pathway from acetaldehyde dehydrogenase system.

NADPH-dependent activity of acetaldehyde oxidation was investigated in microsomes by assaying [14C]acetic acid produced from [14C]acetaldehyde with ion-exchange column. Rat hepatic microsomes exhibited acetaldehyde oxidation activity in the presence of NADPH. This activity was induced 2-fold by the treatment of rats with ethanol. We designated this NADPH-dependent oxidation system as microsomal acetaldehyde-oxidizing system (MAOS), to distinguish from the NAD-dependent acetaldehyde oxidation system by acetaldehyde in mitochondria and cytsol. We further investigated essential enzymes contributing to MAOS activity. Acetaldehyde oxidation activity was investigated in eight forms of purified P-450 in a reconstituted system. Cytochrome P-450 (CYP) 2E1 had the highest oxidation activity and CYP1A2 and CYP4A2 had the next highest activity. Other forms had low activity. To assess the contribution of these forms to MAOS activity, immunoblot was done. CYP2E1 was induced 2-fold by ethanol treatment, but CYP1A2 and CYP4A2 were not reflecting the MAOS activity increased by ethanol treatment. These results suggest that CYP2E1 is the essential enzyme in the MAOS of rats.

Acetaldehyde↗

PubMed1996

Detection of breast cancer micrometastases in axillary lymph nodes by means of reverse transcriptase-polymerase chain reaction. Comparison between MUC1 mRNA and keratin 19 mRNA amplification.

Usefulness of MUC1 mRNA and keratin 19 mRNA as a target of reverse-transcriptase polymerase chain reaction (RT-PCR) was compared in the detection of breast cancer micrometastases in axillary lymph nodes. RT-PCR amplification of MUC1 mRNA and keratin 19 mRNA was conducted using total RNA samples. RT-PCR products were stained with ethidium bromide and analyzed by agarose gel electrophoresis. Expression of both MUC1 mRNA and keratin 19 mRNA was detected by RT-PCR in a breast cancer cell line (MRK) and in all the 23 primary breast cancers but not in the control lymph nodes obtained from patients with benign diseases. A serial dilution study of MRK cells against normal lymph node cells has shown that detection sensitivity of MUC1 RT-PCR and keratin 19 RT-PCR were 1/10(5) and 1/10(6) (cancer/lymph node cells), respectively. Sixty-three axillary lymph nodes were obtained from 23 patients with primary breast cancer, and metastases in each lymph node were investigated by histological examination (hematoxylin and eosin sections) and RT-PCR method. In all 10 lymph nodes, which were histologically metastasis-positive, both MUC1 mRNA and keratin mRNA were detected by RT-PCR. Of the 53 histologically negative lymph nodes, 3 (6%) and 5 (9%) lymph nodes were found to express MUC1 mRNA and keratin 19 mRNA, respectively, indicating the presence of micrometastases which could be detected by RT-PCR but not by histological examination. These results demonstrate the usefulness of both MUC1 RT-PCR and keratin 19 RT-PCR in the detection of breast cancer micrometastases in lymph nodes, and also indicate the superiority of keratin 19 RT-PCR over MUC1 RT-PCR because of its higher detection sensitivity.

Axilla↗

PubMed1996

Microsomal ethanol oxidizing system activity by human hepatic cytochrome P450s.

To assess the contribution of cytochrome P450 (P450) to the microsomal ethanol oxidation system (MEOS) in humans, we examined ethanol oxidization activity in human hepatic microsomes and multiple forms of human hepatic P450s expressed in B-lymphoblastoid cells. Acetaldehyde produced by the MEOS was converted into a fluorescent derivate with cyclohexane-1,3-dione and analyzed by high-performance liquid chromatography using a fluorescence detector. The ethanol oxidation activity of seven forms of human P450s was investigated. P450s 2E1 and 1A2 formed acetaldehyde at high rates. In immunoinhibition studies, anti-P450 2E1 antibody inhibited the ethanol oxidation activity of human hepatic microsomes by 54%, and anti-P450 1A2 antibody inhibited ethanol oxidation activity by 21%. 7,8-Benzoflavone, an inhibitor of P450 1A forms, also inhibited this activity by 38%. The correlation of ethanol oxidation activity with the levels of immunoreactive P450 2E1 in individual human microsomes was highly significant (r = 0.91, P < .001), and the correlation of ethanol oxidation activity with the levels of P450 1A2 was also highly significant (r = 0.87, P < .001). The Km values of P450s 2E1 and 1A2 for ethanol oxidation were 16.5 and 23.6 mM, respectively. These results indicated that P450 2E1 was a major contributor to the MEOS in humans; however, P450 1A2 was considered to play an important role in the MEOS.

Adolescent↗

PubMed1996

[Clinical value of carbohydrate antigens, sialyl Lewis-x and sialyl Lewis-a in gastrointestinal cancer].

To evaluate clinical importance of the expression of sialyl Lewis-X (sLe(x)) and sialyl Lewis-a antigen (sLe(a)) in gastrointestinal cancers, we examined immunohistochemically expression of the two antigens in esophageal, gastric, colorectal, and pancreatic cancer. Expression of sLe(x) and sLe(a) were associated with several clinicopathologic features which reflect tumor aggressiveness in esophageal, gastric and colorectal cancer, but not in pancreatic cancer. In esophageal and colorectal cancer, survival rate of the patients with sLe(x) positive tumors was significantly poorer than that of the patients with sLe(x) negative tumors, while in gastric cancer that with sLe(a) positive tumors was significantly poorer than that with sLe(a) negative. Cox's multivariate analysis revealed that sLe(x) expression status was one of the significant discriminants of prognosis in colorectal cancer patients and sLe(a) status in gastric cancer patients. These results suggest that sLe(x) and sLe(a) expression could be involved in aggressiveness of gastrointestinal cancer and might prove to be a potent marker for prognosis in patients with gastric cancer and colorectal cancer.

Adult↗

PubMed1996

Suppressed expression of phenobarbital-inducible hepatic cytochrome P-450s in Eisai-hyperbilirubinuria rats (EHBR/Eis).

The differential induction of hepatic cytochrome P-450 (P450) was studied in Eisai-hyperbilirubinuria rats (EHBR/Eis). This rat is a mutant that has as high a concentration of bilirubin in the urine as in the plasma. A single administration of trans-stilbene oxide (TSO, 2 mmol/kg), a phenobarbital (PB)-type P450 inducer, did not increase total P450, the CYP2B1/2 or the CYP2C6 in EHBR/Eis liver. TSO was able to induce delta-aminolevulinic acid synthetase and heme oxygenase, rate-limiting enzymes in heme biosynthesis and degradation, respectively, in both EHBR/Eis and Sprague-Dawley rat (SDR), the strain from which EHBR/Eis is derived. TSO also produced similar effects on glutathione depletion and on the activities of other drug-metabolizing enzymes in both strains. A 23-fold increase in CYP2B1/2 mRNA in the SDR liver was observed 24 hr after TSO treatment. In the EHBR/Eis strain, however, TSO increased CYP2B1/2 mRNA only 2-fold. In addition, repeated injection of TSO failed to induce P450 isozymes, CYP2B1/2, CYP2C6 or CYP3A2 in EHBR/Eis. On the other hand, there was essentially no difference in the induced levels of CYP1A1/2 apoprotein and mRNA between twins of SDR and EHBR/Eis livers treated with 3-methylcholanthrene or 1-benzylimidazole. The increased levels of both CYP2B1/2 apoprotein and mRNA from EHBR/Eis liver treated with TSO and 1-benzylimidazole were much smaller (2.5- and 5-fold increases, respectively) than from the SDR liver (17.5- and 15-fold increases, respectively). Although PB expressed CYP2B1/2 apoprotein and mRNA to a similar extent in both homozygous and heterozygous EHBR/Eis livers, CYP3A2 and CYP2C6 were less responsive to PB in homozygous EHBR/Eis. Repeated treatment with TSO induced these isozymes in heterozygote but not in homozygote. These findings suggest that the suppressed expression of PB-inducible P450 isozyme genes in the EHBR/Eis liver may be a general phenomenon associated with PB-type inducers. Therefore, EHBR/Eis may be experimentally useful for studying the mechanism of P450 induction by PB and PB-type inducers.

Animals↗

PubMed1996

[Adjuvant chemotherapy for advanced gastric cancer].

For recent 40 years, many authors reported the results of adjuvant chemotherapy for advanced gastric cancer including 5-fluorouracil, uracil and tegafur, mitomycin C, cytosine arabinoside. OK-432 adriamycin, methotrexate, and cis-pltatin in solitary use of combinations. It is difficult to find a standard effective adjuvant chemotherapy for advanced gastric cancer in these reports. The reasons of this unclearness were as follows; (1) In phase III studies, surgery alone was not a control group in some reports. (2) The number of patients was too small to evaluate statistically. (3) Inter-institutional differences had important roles in the results of multicenter study in the other studies. For the future plans on adjuvant chemotherapy, it is important to make a simple designed protocol, and perform it as a multicenter study including institutions with minimum inter-institutional differences.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1995

Progression of fibroadenoma to phyllodes tumor demonstrated by clonal analysis.

BACKGROUND: The histogeneses of fibroadenoma and phyllodes tumor of the breast appear to be closely related, but it is still unclear whether fibroadenoma can progress directly to phyllodes tumor. METHODS: This issue was studied by conducting clonal analysis of fibroadenoma and phyllodes tumors that were obtained sequentially from the same patient. One patient developed local recurrence of phyllodes tumor twice, and the other two patients each developed a phyllodes tumor after excision of a primary fibroadenoma. The method for clonal analysis was based on trinucleotide repeat polymorphism of the X chromosome-linked androgen receptor (AR) gene and on random inactivation of the gene by methylation. RESULTS: Clonal analysis revealed that all the three primary fibroadenomas were monoclonal and all four recurrent phyllodes tumors were also monoclonal in origin. In addition, the same allele of the AR gene was inactivated in fibroadenoma and phyllodes tumor(s) in each patient. The probability that phyllodes tumors of different origin happen to inactivate the same allele of the AR gene as fibroadenomas in every case is quite low. Rather, it is more reasonable to assume that the phyllodes tumor has the same origin as fibroadenoma. CONCLUSIONS: These results identified monoclonal fibroadenomas that can progress to phyllodes tumors.

Adult↗

PubMed1995

Induction of CYP isoenzymes in various organs of rats by 3-methylcholanthrene or beta-naphthoflavone.

Induction of cytochrome P450 (CYP) isoenzymes in various organs of rats treated with 3-methylcholanthrene (3-MC) and beta-naphthoflavone (BNF) was immunohistochemically and biochemically investigated. Fifteen male F344 rats were divided into three equal groups. Group 1 was untreated as a control. On days 3, 4, 13 and 14, group 2 animals received 3-MC (20 mg/kg body wt i.p.) dissolved in corn oil while group 3 animals were given BNF (50 mg/kg body wt i.p.) dissolved in corn oil, at days 1, 2, 3, 4, 11, 12, 13 and 14. On days 4 and 14, two or three animals in each group were sacrificed, 15 h after administration of the last test compound. Induction of CYP 1A1, 2C11, 2D1, 2E1, 3A2 and 4A1 in various organs was immunohistochemically examined and the levels of CYP 1A1 protein were measured by Western blotting. 3-MC and BNF induced CYP isoenzymes not only in the liver, but also in the small intestine, large intestine, prostate and seminal vesicles. The results indicate that xenobiotic metabolism can occur in various organs.

Animals↗

PubMed1995

Enhancement of in vitro tumor-cell transcellular migration by tumor-cell-secreted endothelial-cell-retraction factor.

To investigate the factors affecting endothelial-cell retraction, we have studied the interaction of tumor cells with endothelial cells in 2 human pancreatic cancer cell lines, PSN-1 and MiaPaca-2. The extent of endothelial-cell retraction measured by the amount of intercellular junctional transport of FITC-dextran through an endothelial monolayer was increased by the addition of a conditioned medium (CM) from both cell lines, while CM from PSN-1 cells was 2 to 3 times more potent than that from MiaPaca-2 cells. After the treatment of endothelial monolayer with CM of PSN-1 cells, the ability of both PSN-1 cells and MiaPaca cells to adhere to or invade the monolayer increased. The addition of CM from PSN-1 cells did not affect the growth rate of either the endothelial or the tumor cells. The activity in the CM was heat-stable and bound to heparin-Sepharose, but was inactivated when treated by 0.5% trypsin. Protease inhibitors did not influence the activity. Pre-treatment of PSN-1 cells by an inhibitor of protein synthesis, cycloheximide, or of protein processing, benzyl-N-acetyl-alpha-D-galactosaminide, reduced endothelial-cell-retraction activity in the CM. The active substance in the CM fractionated in the molecular-weight range of 10,000 to 50,000. These results suggest that PSN-1 cells produce and secrete (a) soluble factor(s) that can induce endothelial-cell retraction, thus facilitating tumor-cell invasion.

Animals↗

PubMed1995

Mutagenic activation of 3-methoxy-4-aminoazobenzene by mouse renal cytochrome P450 CYP4B1: cloning and characterization of mouse CYP4B1.

A new P450 responsible for mutagenic activation of 3-methoxy-4-aminoazobenzene (3-MeO-AAB) which is a potent procarcinogen was purified from renal microsomes of male mice using an index of umu gene expression. The purified P450 had high bioactivation toward 3-MeO-AAB and also 2-aminofluorene and 2-aminoanthracene. The antibody against this P450 completely inhibited mutagenic activation of 3-MeO-AAB of mouse renal microsomes. With immunoblotting, this form was present abundantly in renal microsomes of male mice but not in those of female mice. This P450 was also present in pulmonary microsomes of male and female mice but not in hepatic microsomes. The NH2-terminal amino acid sequence analysis indicated that this form belonged to the CYP4B subfamily. Thus, mouse kidney cDNA library was screened with rat CYP4B1 probe. The cDNA-deduced amino acid sequence of isolated cDNA consisted of 511 amino acids and bore 90, 86, and 84% similarities to rat, rabbit, and human CYP4B1, respectively. The NH2-terminal amino acid sequence of the purified renal P450 and amino acid sequence of BrCN-digested peptides from the purified P450 agreed with the cDNA-deduced amino acid sequence. These results suggest that CYP4B1 is a major form in renal microsomes of male mice and plays a major role in mutagenic activation of 3-MeO-AAB. In extrahepatic tissue, CYP4B1 may contribute to chemical carcinogenesis.

Amino Acid Sequence↗

PubMed1995

Genetic diagnosis of lymph-node metastasis in colorectal cancer.

If a regional lymph node taken during surgery for colorectal cancer is found to be free of tumour on histological examination this is taken to be a good sign. However, conventional staining may not be sensitive enough. Mutant-allele-specific amplification (MASA) is a technique that can detect, at the level of an individual cell, micrometastases to lymph nodes that are histologically diagnosed as negative. To examine the prognostic significance of such genetically detectable tumour cells we screened 120 colorectal cancers from patients who had no histologically detectable lymph-node metastasis at the time of surgery for mutations in K-ras (codons 12, 13, and 61) or p53 (exons 5-8). Somatic mutations were identified by MASA in 71 tumours. We next examined preserved tissues from corresponding regional lymph nodes, using MASA to look for the specific mutation found in the primary. Of 37 patients with genetically positive lymph nodes 27 had had a tumour recurrence within 5 years of surgery; none of the 34 patients who were MASA negative for lymph node metastasis had had a recurrence. Genetic diagnosis of lymph node metastasis may be a useful prognostic factor in colorectal cancer, and it could also serve as a selective marker for intensive postoperative adjuvant chemotherapy.

Colorectal Neoplasms↗

PubMed1995

Purification and characterization of a form of cytochrome P450 from bear liver microsomes.

A form of P450 [termed P450(b-1)] was purified from male bear liver microsomes. The specific content of the final P450(b-1) preparation was 11.26 nmol/mg protein, and recovery was 0.20% of the microsomal P450. The apparent molecular weight of P450(b-1) was 54,000. The absorption spectrum of P450(b-1) indicated that this protein was a low- and high-spin mixed type P450 in the oxidized form. The carbon monoxide complex of reduced P450(b-1) showed an absorption peak at 450.5 nm. The reconstituted system containing P450(b-1) catalyzed the metabolism of aminopyrine, benzo[a]pyrene, 7-ethoxycoumarin, imipramine and propranolol, of which P450(b-1) most strongly catalyzed aminopyrine N-demethylation and imipramine N-demethylation. The N-terminal amino acid sequence of P450(b-1) was highly homologous to that of P450-D1 from liver microsomes of male beagle dogs. P450(b-1) showed similarities in spectral properties, N-terminal amino acid sequence, and catalytic activities to rat P450 2C11. P450(b-1) was immunochemically cross-reactive with anti-P450 2C11 antibody and very weakly cross-reactive with anti-P450 2E1 antibody, but did not react with anti P450 1A1 or 2B1 antibodies. On the basis of these results, we suggest that P450(b-1) belongs to the P450 2C subfamily.

Amino Acid Sequence↗

PubMed1995

Clonal analysis of benign and malignant human breast tumors by means of polymerase chain reaction.

Clonal analysis was conduced on a variety of benign and malignant human breast tumors using the method based on restriction fragment length polymorphism (RFLP) of the X 120 chromosome-linked phosphoglycerokinase gene and on random inactivation of the gene by methylation. Breast carcinoma was shown to be monoclonal in origin, consistent with a somatic mutational theory. Precancerous lesions such as atypical ductal hyperplasia and multiple intraductal papilloma were also found to be monoclonal, indicating that certain genetic changes had been accumulated in these lesions. Solitary intraductal papilloma was found to be monoclonal. Since this tumor is composed of two types of cells, luminal epithelial cells and myoepithelial cells, it was suggested that the origin of solitary intraductal papilloma is a precursor cell which is capable of differentiating into both luminal and myoepithelial cells. The fact that fibroadenoma is polyclonal indicates that this tumor is not neoplasia but hyperplasia of a lobule. Epithelial component of phyllodes tumor was found to be polyclonal but stromal component was found to be monoclonal. Thus, phyllodes tumor is considered to be a neoplasm of stromal cells but not of epithelial cells.

Base Sequence↗