Phytoestrogens/Flavonoids Reverse Breast Cancer Resistance Protein/ABCG2-Mediated Multidrug Resistance

Breast cancer resistance protein (BCRP), also called ABCG2, confers resistance to anticancer agents such as 7-ethyl-10-hydroxycamptothecin (SN-38), mitoxantrone, and topotecan. We found previously that sulfated estrogens are physiologic substrates of BCRP. Flavonoids with weak estrogenic activities are called phytoestrogens. In this study, we show that phytoestrogens/flavonoids, such as genistein, naringenin, acacetin, and kaempferol, potentiated the cytotoxicity of SN-38 and mitoxantrone in BCRP-transduced K562 (K562/BCRP) cells. Some glycosylated flavonoids, such as naringenin-7-glucoside, also effectively inhibited BCRP. These flavonoids showed marginal effect on the drug sensitivity of K562 cells. Genistein and naringenin reversed neither P-glycoprotein-mediated vincristine resistance nor multidrug resistance-related protein 1-mediated VP-16 resistance. Genistein and naringenin increased cellular accumulation of topotecan in K562/BCRP cells. K562/BCRP cells also accumulated less [(3)H]genistein than K562 cells. [(3)H]genistein transport in the basal-to-apical direction was greater in BCRP-transduced LLC-PK1 (LLC/BCRP) cells, which express exogenous BCRP in the apical membrane, than in parental cells. Fumitremorgin C abolished the increased transport of [(3)H]genistein in LLC/BCRP cells compared with parental cells. TLC analysis revealed that genistein was transported in its native form but not in its metabolized form. These results suggest that genistein is among the natural substrates of BCRP and competitively inhibits BCRP-mediated drug efflux. The results have two important clinical implications: (a) flavonoids and glycosylated flavonoids may be useful in overcoming BCRP-mediated drug resistance in tumor cells; and (b) coadministration of flavonoids with BCRP-substrate antitumor agents may alter the pharmacokinetics and consequently increase the toxicity of specific antitumor agents in cancer patients.

Breast cancer resistance protein exports sulfated estrogens but not free estrogens

Breast cancer resistance protein (BCRP), an ATP-binding cassette transporter, confers resistance to a series of anticancer reagents such as mitoxantrone, 7-ethyl-10-hydroxycamptothecin, and topotecan. We reported previously that estrone and 17beta-estradiol reverse BCRP-mediated multidrug resistance. In the present study, we demonstrate that BCRP exports estrogen metabolites. First, we generated BCRP-transduced LLC-PK1 (LLC/BCRP) cells, in which exogenous BCRP is expressed in the apical membrane, and investigated transcellular transport of 3H-labeled compounds using cells plated on microporous filter membranes. The basal-to-apical transport (excretion) of mitoxantrone, estrone, and 17beta-estradiol was greater in LLC/BCRP cells than in LLC-PK1 cells. Thin-layer chromatography of transported steroids revealed that the transport of estrone and 17beta-estradiol was independent of BCRP expression. Alternatively, increased excretion of estrone sulfate and 17beta-estradiol sulfate was observed in LLC/BCRP cells. BCRP inhibitors completely inhibited the increased excretion of sulfated estrogens across the apical membrane. Conversion of estrogens into their sulfate conjugates was similar between LLC/BCRP and LLC-PK1 cells, suggesting that the increased excretion of estrogen sulfates was attributable to BCRP-mediated transport. Next, the uptake of 3H-labeled compounds in membrane vesicles from BCRP-transduced K562 (K562/BCRP) cells was investigated. 3H-labeled estrone sulfate, but not 3H-labeled estrone or 17beta-estradiol, was taken up by membrane vesicles from K562/BCRP cells, and this was ATP-dependent. Additionally, BCRP inhibitors suppressed the transport of estrone sulfate in membrane vesicles from K562/BCRP cells. These results suggest that BCRP does not transport either free estrone or 17beta-estradiol but exports sulfate conjugates of these estrogens.

Risk factors for recurring hepatocellular carcinoma differ according to infected hepatitis virus-an analysis of 236 consecutive patients with a single lesion

Patients with hepatocellular carcinoma (HCC) frequently experience intrahepatic HCC recurrence even after complete ablation of primary lesions. Because the oncogenic process may be different for hepatitis B viral (B-viral) and hepatitis C viral (C-viral) HCC, the present study was conducted to elucidate the factors contributing to HCC recurrence with respect to the infected hepatitis virus. Two hundred thirty-six patients with a single HCC lesion who underwent complete ablation of the tumor by PEIT and/or PMCT or surgical resection at Tokyo University and its affiliated hospitals from 1993 to 1997 were enrolled. The patients were classified into 3 groups: the B-viral group, C-viral group, and NBNC group. After complete removal of tumors, the patients were followed for a mean period of 39 months. The factors contributing to HCC recurrence were analyzed by univariate and multivariate analysis using the Cox proportional hazard model. The rate of intrahepatic recurrence in enrolled patients at 1, 3, and 5 years was 19%, 50%, and 64%, respectively. The intrahepatic recurrence rate in C-viral and B-viral HCC was higher than that in the NBNC-related HCC. Fibrosis staging, pathological grading of HCC, and serum AFP levels were significantly linked to intrahepatic recurrence by univariate analysis, and fibrosis staging was strongest in the multivariate analysis for C-viral HCC (P = .004). In contrast, fibrosis staging did not affect the recurrence in B-viral (P = .51) and NBNC-related (P = .77) HCC. Risk factors for HCC recurrence differed according to the infected viral state.

Molecular pathogenesis of sporadic colorectal cancers

Colorectal cancer (CRC) results from the progressive accumulation of genetic and epigenetic alterations that lead to the transformation of normal colonic mucosa to adenocarcinoma. Approximately 75% of CRCs are sporadic and occur in people without genetic predisposition or family history of CRC. During the past two decades, sporadic CRCs were classified into three major groups according to frequently altered/mutated genes. These genes have been identified by linkage analyses of cancer-prone families and by individual mutation analyses of candidate genes selected on the basis of functional data. In the first half of this review, we describe the genetic pathways of sporadic CRCs and their clinicopathologic features. Recently, large-scale genome analyses have detected many infrequently mutated genes as well as a small number of frequently mutated genes. These infrequently mutated genes are likely described in a limited number of pathways. Gene-oriented models of CRC progression are being replaced by pathway-oriented models. In the second half of this review, we summarize the present knowledge of this research field and discuss its prospects.

Determination of Helicobacter pylori virulence by simple gene analysis of the cag pathogenicity island

Nucleic acid amplification was performed for five loci in the cag pathogenicity island (PAI) of Helicobacter pylori (comprising cagA, the cagA promoter region, cagE, cagT, and the left end of cagII [LEC]), and gastric inflammation in patients was evaluated. Of 204 H. pylori isolates from Japanese patients (53 with peptic ulcer, 55 with gastric cancer, and 96 with chronic gastritis), 197 (96.6%) were positive for all five loci. Two isolates (1%) were negative for all five loci, and five isolates (2.4%) were positive for only cagA and LEC. These latter seven isolates were all from patients with mild chronic gastritis. Neutrophil infiltration in gastric mucosa was significantly milder in patients infected with partially or totally deleted-PAI strains than in those with intact-PAI strains. The cagE gene was a more accurate marker of an intact cag PAI than the cagA gene, and cagE seemed to be more useful in discriminating between H. pylori strains causing different rates of disease progression.

Nuclear expression of phosphorylated EGFR is associated with poor prognosis of patients with esophageal squamous cell carcinoma

OBJECTIVES

Although it has been reported that epidermal growth factor receptor (EGFR) is able to translocate from the plasma membrane to the nucleus, the pathophysiological role of this translocation in tumorigenicity is still unclear. In the present study, to elucidate the pathophysiological significance of EGFR translocation, we investigated the expression not only of conventional EGFR but also its phosphorylated form (pEGFR), focusing on its cellular localization in esophageal cancer tissues.

METHODS

Fifty-two specimens of esophageal squamous cell carcinoma (SCC) obtained by surgery were examined immunohistochemically for their EGFR and pEGFR immunostaining patterns. The relationships between clinicopathological parameters and EGFR or pEGFR immunostaining patterns were then analyzed.

RESULTS

In 37 (71.2%) of the 52 esophageal SCCs, EGFR immunoreactivity was clearly localized at the plasma membrane of the cancer cells, whereas pEGFR immunoreactivity was clearly localized in the nucleus in 19 (36.5%) cases. Nuclear expression of pEGFR significantly correlated with TNM stage and lymph node metastasis, and moreover was associated with a poor outcome of esophageal SCC.

CONCLUSIONS

Nuclear translocalization of pEGFR is associated with an increase in the malignant potential of esophageal SCC and may affect prognosis in patients with esophageal SCC.

Colonic expression of heme oxygenase-1 is associated with a better long-term survival in patients with colorectal cancer

OBJECTIVE

Heme oxygenase-1 (HO-1) has emerged as a crucial mediator of mucosal defense in the gastrointestinal tract. Its metabolic pathway products, biliverdin/bilirubin and carbon monoxide, can reduce oxidative stress and inflammation, and promote resistance to apoptosis. The role of HO-1 in gastrointestinal malignancies, however, remains to be elucidated. The purpose of this study was to analyze HO-1 expression in human colon adenoma and cancer samples.

MATERIAL AND METHODS

Fifty-five paraffin-embedded surgical specimens of colorectal cancer and 19 colonic adenoma samples were stained immunhistochemically for HO-1 expression using an anti-HO-1 monoclonal antibody. HO-1 expression was evaluated independently by two different investigators and subsequently correlated to clinical data and patients' life expectancy.

RESULTS

Focal HO-1 expression could be documented in 41.8% (23/55) of patients with colorectal cancer. HO-1 expression in colonic adenoma was detectable in 36.8% (7/19) of cases. The rate of lymphatic tumor invasion was significantly lower in colorectal cancer samples expressing HO-1 (p=0.048). Additionally, fewer lymph node metastases were found in colorectal cancer samples with HO-1 expression, but these differences did not reach statistical significance. Mean observation period was 65.87+/-3.96 months. Kaplan-Meier analysis showed a significantly better survival for colorectal cancer patients with colonic HO-1 expression (p=0.018).

CONCLUSIONS

This study demonstrates that colonic HO-1 may be a prognostic marker of colorectal-cancer outcome.

Mutational inactivation of mitotic checkpoint genes, hsMAD2 and hBUB1, is rare in sporadic digestive tract cancers

Genetic instability is a key mechanism of tumorigenesis, and the instability exists at two distinct levels, the nucleotide and the chromosome levels. Disruption of the mitotic spindle checkpoint is one of the underlying mechanisms leading to aneuploidy and alterations of hsMAD2 and hBUB1, assumed to take part in the spindle checkpoint in human cells, have been found to be associated with chromosomal instability in some tumor cell lines. Therefore, we investigated the mutational status of the hsMAD2 and hBUB1 genes in 32 sporadic digestive tract cancers by reverse transcription-polymerase chain reaction-single strand conformation polymorphism analysis. The entire coding sequence of the hsMAD2 gene, and conserved regions (codons 21-152 and codons 732-1043) presumed to be functionally important in the hBUB1 gene were analyzed. Mutation of the hsMAD2 gene was not observed at all and missense mutation of the hBUB1 gene was noted in one rectal cancer case. Sequencing analysis revealed an AGT-to-GGT missense mutation, substituting glycine for serine, at codon 950, which is conserved between budding yeast and human. These results indicate that mutations of the hsMAD2 and hBUB1 genes are very rare and presumably play a very restricted role in tumor development of sporadic cancers.

Estrone and 17beta-estradiol reverse breast cancer resistance protein-mediated multidrug resistance

Breast cancer resistance protein (BCRP), an adenosine triphosphate-binding cassette transporter, confers resistance to a series of anticancer reagents, including mitoxantrone, SN-38 and topotecan. In the present study, we found that estrone and 17beta-estradiol potentiated the cytotoxicity of mitoxantrone, SN-38 and topotecan in BCRP-transduced K562 cells (K562 / BCRP). These estrogens showed only a marginal effect, or none, in parental K562 cells. Estrone and 17beta-estradiol increased the cellular accumulation of topotecan in K562 / BCRP cells, but not in K562 cells, suggesting that these estrogens inhibit the BCRP-mediated drug efflux and overcome drug resistance.

Single amino acid substitutions in the transmembrane domains of breast cancer resistance protein (BCRP) alter cross resistance patterns in transfectants

Breast cancer resistance protein (BCRP) is a member of ATP-binding cassette transporters that has an N-terminal ATP binding domain and a C-terminal transmembrane domain (TM). Expression of wild-type BCRP confers resistance to multiple chemotherapeutic agents such as mitoxantrone, SN-38 and topotecan, but not to doxorubicin. We made 32 BCRP mutants with an amino acid substitution in the TMs (7 E446-mutants in TM2, 15 R482-mutants in TM3, 4 N557-mutants in TM5 and 6 H630-mutants in TM6) and examined the effect of the substitutions on cellular drug resistance. PA317 cells transfected with any one of the 7 E446-mutant BCRP cDNAs did not show drug resistance. Cells transfected with any one of the 13 R482X2-BCRP cDNAs (X2 = N, C, M, S, T, V, A, G, E, W, D, Q and H, but not Y and K) showed higher resistance to mitoxantrone and doxorubicin than the wild-type BCRP-transfected cells. Cells transfected with N557D-BCRP cDNA showed similar resistance to mitoxantrone but lower resistance to SN-38 than the wild-type BCRP-transfected cells. Cells transfected with N557E-, H630E- or H630L-BCRP cDNA showed similar degrees of resistance to mitoxantrone and SN-38. Estrone and fumitremorgin C reversed the drug resistance of cells transfected with R482-, N557- or H630-mutant BCRP cDNA. Cells transfected with R482G- or R482S-BCRP cDNA showed less intracellular accumulation of [3H]mitoxantrone than the wild-type BCRP-transfected cells. These results suggest that E446 in TM2, R482 in TM3, N557 in TM5 and H630 in TM6 play important roles in drug recognition of BCRP.

Mutations of the Ki-ras, p53 and APC genes in adenocarcinomas of the human small intestine

In contrast to the origins of colorectal carcinomas, the mechanisms of carcinogenesis in the small intestine remain unclear. We therefore analyzed the mutational status of the Ki-ras, p53, and adenomatous polyposis coli (APC) genes in primary carcinomas of the small intestine and compared the mutation patterns with those established for colorectal cancers. DNA was extracted from 15 formalin-fixed, paraffin-embedded lesions. Codons 12, 13 and 61 of the Ki-ras gene, exons 5-8 of the p53 gene, and codons 1268-1569, which contain the mutation cluster region (MCR) of the APC gene, were amplified by means of PCR, subcloned and sequenced. Mutations of the Ki-ras and p53 genes were observed in 8 (53.3%) and 4 lesions (26.7%), respectively. The mutational frequency of the Ki-ras gene in the present series of small intestinal carcinomas was similar, while that of the p53 gene was slightly lower than the reported frequencies for colorectal carcinomas. Only one case showed a mutation of the APC gene, involving an insertional mutation of an adenine at codons 1554-1556 with formation of a stop codon immediately downstream. Since the occurrence of an APC mutation is considered an early event in colorectal carcinogenesis, our findings indicating an extremely low frequency of such changes in and around the MCR suggest that carcinomas of the small intestine arise via a genetic pathway distinct from that involved in the development of carcinomas of the colorectum.

Differential mucin phenotypes and their significance in a variation of colorectal carcinoma

AIM

To investigate mucin expression profiles in colorectal carcinoma (CRC) histological subtypes with regard to clinicopathologic variables and prognosis.

METHODS

Mucin (MUC)2 and MUC5AC expressions were assessed by immunohistochemistry for a total of 250 CRC cases that underwent surgical resection. CRCs included 63 well-to-moderately differentiated adenocarcinomas (WMDAs), 91 poorly differentiated adenocarcinomas (PDAs), 81 mucinous adenocarcinoma (MUAs), and 15 signet-ring cell carcinomas (SRCCs). MUC2 and MUC5AC were scored as positive when ≥ 25% and ≥ 1% of cancer cells were stained positive, respectively. The human mutL homolog 1 and human mutS homolog 2 expressions were assessed by immunohistochemistry in PDAs to investigate mismatch-repair (MMR) status. Tumors that did not express either of these two were considered MMR-deficient. Results were analyzed for associations with clinicopathologic variables and the prognosis in individual histological CRC subtypes.

RESULTS

MUC2-positive and MUC5AC-positive WMDA percentages were 49.2% and 30.2%, respectively. In contrast, MUC2-positive and MUC5AC-positive PDA percentages were 9.5% and 51.6%, respectively. MUC2 levels tended to decrease and MUC5AC levels tended to increase from WMDA to PDA. In 21 tumors comprising both adenoma and adenocarcinoma components in a single tumor (4 WMDAs, 7 PDAs, and 10 MUAs), MUC2 was significantly downregulated in PDA and MUC5AC was downregulated in PDA and MUA in the adenoma-carcinoma sequence. These results suggested that MUC2 levels might be associated with malignant potential and that MUC5AC expression was an early event in tumorigenesis. Despite worse prognoses than WMDA, high MUC2 expression levels were maintained in MUA (95.1%) and SRCC (71.5%), which suggested a pathogenesis for these subtypes distinct from that of WMDA. No significant associations were found between MUC2 expression and any clinicopathologic variables in any histological subtype. MUC5AC expression in PDA was closely associated with right-sided location (P = 0.017), absence of nodal metastasis (P = 0.010), low tumor node metastasis stage (P = 0.010), and MMR deficiency (P = 0.003). MUC2 expression in WMDA was a marginal prognostic factor for recurrence/metastasis-free survival (RFS) by univariate Cox analysis (P = 0.077) but not by multivariate Cox analysis (P = 0.161). MUC5AC expression in PDA was a significant prognostic factor for RFS by univariate Cox analysis (P = 0.007) but not by multivariate Cox analysis (P = 0.104). Kaplan-Meier curves and log-rank tests revealed that MUC2 expression was marginally associated with a better WMDA prognosis [P = 0.064 for RFS and P = 0.172 for overall survival (OS)] but not for PDA. In contrast, MUC5AC expression was significantly and marginally associated with a better PDA prognosis in terms of RFS and OS, respectively (P = 0.004 for RFS and P = 0.100 for OS), but not for WMDA and MUA.

CONCLUSION

Mucin core protein expression profiles and clinical significance differ according to histological CRC subtypes. This may reflect different pathogeneses for these tumors.

Prediction of colorectal neoplasia by quantitative methylation analysis of estrogen receptor gene in nonneoplastic epithelium from patients with ulcerative colitis

PURPOSE

The incidence of colorectal neoplasia has increased among patients with longstanding and extensive ulcerative colitis (UC). Therefore, surveillance colonoscopy has been widely recommended. However, there is controversy about the impact of cancer surveillance, and ways to improve its effectiveness are being sought. The estrogen receptor (ER) gene shows age-related methylation in the colorectal epithelium and is frequently methylated in colorectal neoplasia, suggesting that ER methylation occurs early in the process of colorectal tumorigenesis.

EXPERIMENTAL DESIGN

To clarify whether methylation analysis of the ER gene in nonneoplastic epithelium can help predict an increased risk for UC-associated neoplasia, a total of 105 nonneoplastic colorectal epithelia from 18 patients with longstanding and extensive UC, including 8 patients with neoplasia and 10 patients without neoplasia, were analyzed. In all patients, multiple samples were taken from six regions of the colorectum. The combined bisulfite restriction analysis method was used to determine the methylation status of the ER gene.

RESULTS

The mean methylation level of the ER gene was 25.4% in the nonneoplastic epithelia from UC patients with neoplasia, whereas it was only 4.0% in those without neoplasia (P<0.001). The methylation level of the ER gene in UC patients with neoplasia was significantly higher than in UC patients without neoplasia throughout the colorectum except for the cecum. In UC patients with neoplasia, the mean ER methylation level in the distal colon (36.1%) was significantly higher than in the proximal colon (14.6%; P<0.001).

CONCLUSIONS

These results suggest that the analysis of ER gene methylation in nonneoplastic colorectal epithelium could have the potential to be a useful adjunct for identifying individuals with longstanding and extensive UC who are at increased risk of neoplasia and contribute to more effective cancer surveillance.

Congenital absence of portal vein with multiple hyperplastic nodular lesions in the liver

Congenital absence of the portal vein is an extremely rare anomaly, in which enteric blood bypasses the liver and drains into the inferior vena cava. A 16-year-old girl was referred to our hospital presenting with liver tumor. Although she had suffered from galactosemia soon after birth, the galactosemia had improved spontaneously 1 year later. Between the ages of 8 and 12 years, chronic hepatitis with a mild elevation of aspartate transaminase (AST) and alanine transaminase (ALT) was observed, but liver tumor had not been detected on computed tomography (CT) in regular medical examinations. However, at age 16, liver tumors, 10 cm in diameter, were found. Abdominal angiography indicated complete absence of the portal vein, suggesting that enteric blood was bypassing the liver and draining into the inferior vena cava. In biopsy specimens obtained under ultrasonographic guidance, liver tumors were confirmed histologically as hyperplastic nodules. In addition to this case report, the clinical features of 25 reported cases of congenital absence of the portal vein are reviewed.

A polymorphism at codon 160 of human O6-methylguanine-DNA methyltransferase gene in young patients with adult type cancers and functional assay

O6-methylguanine-DNA methyltransferase (MGMT) plays an important role in repair of alkylating agent-induced DNA damage. Among the alkylation products of DNA, O6-methylguanine is one of the most critical lesions leading to the induction of mutations. The enzyme MGMT transfers the methyl group from O6-methylguanine of DNA to its own cysteine residue. Although mutations of other DNA repair genes involved in nucleotide excision repair and mismatch repair have been proven to be related to human tumorigenesis, the question of whether MGMT gene mutation might play a role in human carcinogenesis has hitherto not been elucidated. If there is a population with decreased enzyme activity due to defective MGMT gene, the affected individuals should be at risk of developing cancer early in life because of an increased susceptibility to alkylating agents. To test this hypothesis, germ line mutations of the MGMT gene were investigated in 12 young patients with adult type cancers (mean, 16.7 years old, 8 hepatocellular carcinomas, 3 gastric cancers, 1 cholangiocellular carcinoma) and 28 elderly patients who died of non-cancer diseases as controls (mean, 66 years old). A point mutation at codon 160 in exon 5, GGA to AGA, converting glycine to arginine was found in three of the young patients (25%), while the same mutation was found in three out of 28 (10.7%) in the control group. The mutated codon was located 15 codons from a functional cysteine residue toward the carboxyl terminal. Investigation of enzyme function, even in cases of bi-allelic mutation, revealed comparable activities for both mutated and wild type MGMT. Thus, we conclude the mutation is a normal polymorphism of the MGMT gene, present in approximately 15% of the population, although this does not rule out a possible influence in other tissues.

Immunohistochemical and molecular analysis of giant cell carcinoma of the pancreas: a report of three cases

We performed molecular biological studies as well as immunohistochemical analysis of three cases of giant cell carcinoma of the pancreas. Histologically, one case was a pleomorphic giant cell carcinoma consisting of pleomorphic giant/ small cells and spindle cells, one an osteoclast-like giant cell tumor composed of osteoclastoid giant cells and pleomorphic small cells, and one a pleomorphic giant cell carcinoma with osteoclastoid giant cells. Immunohistochemically, pleomorphic giant cells and small pleomorphic cells were positive for epithelial and mesenchymal markers throughout the cases. Osteoclastoid cells were strongly positive for PG-M1 (CD68), but negative for lysozyme and epithelial markers. Pleomorphic spindle cells showed the same immunoreactivity as pleomorphic giant/small cells. Genetically, all cases contained a mutation in the K-ras (codons 12, 13) oncogene, but neither p53 (exons 5-8) nor p16INK4 (exons 1, 2) gene mutations were found in any case. Furthermore, Loss of heterozygosity (LOH) of the p53, p161NK4. APC, and DPC4 gene loci was not found in any of the cases. Immunohistochemical study demonstrated this tumor to be of epithelial origin with mesenchymal differentiation. Genetically, initiation of the tumor is similar to that of usual ductal adenocarcinoma, but progression might be rather different. The peculiar histologic and biologic features of this tumor would be the result of changes in other functional genes.

Mutational analysis of the p53 and K-ras genes and allelotype study of the Rb-1 gene for investigating the pathogenesis of combined hapatocellular-cholangiocellular carcinomas

Because combined hepatocellular-cholangiocellular carcinoma is rare and its biological features and pathogenesis have not been well established, we investigated alterations of the p53, K-ras and Rb-1 genes, as well as expression patterns of carcinoembryonic antigen and keratin, in seven combined hepatocellular-cholangiocarcinomas out of 557 hepatocellular carcinomas autopsied at Tokyo University during 30 years. Mutations of the p53 gene were found in two cases, at codon 244 (GGC to TGC) in the cholangiocellular carcinoma component of case 1 (mixed type, showing an intimate intermingling of both elements) and at codon 234 (TAC to AAC) in both components of case 5 (combined type, consisting of contiguous but independent masses of both elements). Mutation of the K-ras gene (codon 12, GGT to GAT) was seen only in the cholangiocellular carcinoma component of clinically apparent double cancer, case 6. Allelic alteration of the Rb-1 gene was observed in two cases, deletion of both alleles in the hepatocellular carcinoma component of case 3 (combined type) and replication error of the same pattern in both components of case 4 (mixed type). Immunohistochemical analysis showed that the hepatocellular carcinoma components of five cases (cases 2, 3, 5, 6, 7) were immunoreactive for keratin, suggesting biliary epithelial transformation. In four of the five cases (cases 3 and 5 combined, case 7 mixed and case 6 double cancer), cholangiocellular carcinoma components were also positive for keratin. These results suggest that both components of combined hepatocellular-cholangiocarcinoma have the same genetic and phenotypic character and might have arisen from the same origin in some cases.

Impact of functional ABCG2 polymorphisms on the adverse effects of gefitinib in Japanese patients with non-small-cell lung cancer

PURPOSE

ABCG2 is a half-size ATP-binding cassette transporter implicated in cellular gefitinib transport. Reportedly, the c.421C > A ABCG2 gene polymorphism was associated with gefitinib-induced diarrhea in Caucasian patients with non-small-cell lung cancer. Since c.421C > A ABCG2, resulting in p.Q141K substitution, is more prevalent in Asian populations, the putative relationship between gefitinib-induced adverse effects and this functional polymorphism was investigated in Japanese patients. c.376C > T, resulting in truncated, non-functional ABCG2, was also investigated.

METHODS

ABCG2 gene polymorphisms were evaluated in 75 patients with non-small-cell lung cancer treated with gefitinib 250 mg/day orally, and results were correlated with treatment-related adverse effects.

RESULTS

Forty (53.3%) patients harbored c.421A ABCG2 on at least one allele, while the remaining 35 (46.7%) were wild type for c.421C > A. No significant group difference was observed in frequency of gefitinib-related diarrhea or other adverse effects. In addition, the only one patient homozygous for the c.421A allele in this study was not affected with gefitinib-induced diarrhea or interstitial lung disease. Two patients (2.7%) were found to harbor the c.376T allele heterozygously. One of the two patients harbored both the c.376T and the c.421A genotypes on distinct alleles. Gefitinib-related interstitial lung disease and severe diarrhea were noted in neither of the two patients.

CONCLUSIONS

In this Japanese population, we did not find an evident association between ABCG2 polymorphisms, c.376C > T and c.421C > A, and susceptibility to gefitinib-induced adverse effects.

Gefitinib reverses breast cancer resistance protein–mediated drug resistance

Breast cancer resistance protein (BCRP) is an ATP binding cassette transporter that confers resistance to a series of anticancer agents such as 7-ethyl-10-hydroxycamptothecin (SN-38), topotecan, and mitoxantrone. In this study, we evaluated the possible interaction of gefitinib, a selective epidermal growth factor receptor tyrosine kinase inhibitor, with BCRP. BCRP-transduced human epidermoid carcinoma A431 (A431/BCRP) cells acquired cellular resistance to gefitinib, suggesting that BCRP could be one of the determinants of gefitinib sensitivity in a certain sort of cells. Next, the effect of gefitinib on BCRP-mediated drug resistance was examined. Gefitinib reversed SN-38 resistance in BCRP-transduced human myelogenous leukemia K562 (K562/BCRP) or BCRP-transduced murine lymphocytic leukemia P388 (P388/BCRP) cells but not in these parental cells. In addition, gefitinib sensitized human colon cancer HT-29 cells, which endogenously express BCRP, to SN-38. Gefitinib increased intracellular accumulation of topotecan in K562/BCRP cells and suppressed ATP-dependent transport of estrone 3-sulfate, a substrate of BCRP, in membrane vesicles from K562/BCRP cells. These results suggest that gefitinib may overcome BCRP-mediated drug resistance by inhibiting the pump function of BCRP. Furthermore, P388/BCRP-transplanted mice treated with combination of irinotecan and gefitinib survived significantly longer than those treated with irinotecan alone or gefitinib alone. In conclusion, gefitinib is shown to interact with BCRP. BCRP expression in a certain sort of cells is supposed to be one of the determinants of gefitinib sensitivity. Gefitinib inhibits the transporter function of BCRP and reverses BCRP-mediated drug resistance both in vitro and in vivo.

Small hyperechoic nodules in chronic liver diseases include hepatocellular carcinomas with low cyclin D1 and Ki-67 expression

In spite of the importance of periodic screening for hepatocellular carcinoma (HCC) by ultrasonography (US) in patients with underlying liver disease, the clinicopathological characteristics of hyperechoic nodules have not been clearly evaluated. The aim of this study was to characterize the pathological and proliferating features of small hyperechoic nodules. Tissue specimens of 55 hyperechoic and 107 hypoechoic nodules less than 20 mm in diameter in patients with chronic liver disease were obtained by echo-guided needle biopsy and examined histopathologically. Of these, 42 (76%) hyperechoic and 56 (52%) hypoechoic nodules were diagnosed as HCC, and 82% of hyperechoic HCCs contained fatty change and/or clear cell change. In addition, immunohistochemical staining using cyclin D1, p53, and Ki-67 was examined. A high-level expression of cyclin D1 was found in only 5% of hyperechoic HCCs, in contrast to 38% of hypoechoic HCCs (P <.02). The labeling index of Ki-67 in hyperechoic HCCs was lower than in hypoechoic HCCs (4.2% vs. 8.9%; P <.003). However, there was no difference on p53 staining between them. Retrospective follow-up study revealed that hyperechoic nodules showed slow growth (doubling time, median: 1,403 days) initially, and came to show rapid growth (doubling time, median: 56 days). From these results, small hyperechoic nodules in chronic liver diseases are worth notice as candidates for well-differentiated HCC with low cyclin D1 and Ki-67 expression.

Frequent somatic mutations of the APC and p53 genes in sporadic ampullary carcinomas

Although a close relation of somatic mutations of the adenomatous polyposis coli gene with ampullary carcinomas in familial adenomatous polyposis patients has been reported, the possible association with sporadic ampullary neoplasms has not been fully examined. We have therefore investigated loss of heterozygosity at the adenomatous polyposis coli locus and the mutational status of a portion of the adenomatous polyposis coli gene, including the mutation cluster region, in 17 ampullary carcinomas of non-familial adenomatous polyposis patients. Alteration of the adenomatous polyposis coli gene was found in 8 of 17 (47.1%) cases, as missense or insertion mutations, with or without loss of heterozygosity. Additional investigation of p53 (exons 5-8) and K-ras (codons 12 and 13) gene mutations revealed a striking mutational pattern of the p53 gene. Nine of the 17 cases demonstrated a total of 12 mutations, 6 clustered at codon 189 and 3 at codon 166. Furthermore, 5 of the 12 mutations were nonsense mutations. Regarding the K-ras gene, 4 of the 17 (23.5%) cases had mutations in codon 12, 3 of the 4 cases being derived from the intraduodenal bile duct. The findings indicate that alterations of the adenomatous polyposis coli and the p53 genes are relatively frequent in sporadic ampullary carcinomas. In particular, the clustering at specific p53 codons might offer an etiological clue to clarify ampullary carcinogenesis. Mutations of the K-ras gene, on the other hand, might be characteristic of intraduodenal bile duct origin.

Adenocarcinoma arising in gastric inverted hyperplastic polyp: a case report and review of the literature

A 54-year-old man, found to have a submucosal tumor in the stomach by double contrast roentgenography, endoscopy, and endoscopic ultrasonography, underwent a laparoscopic partial gastrectomy. The pathological examination revealed that the lesion, measuring 45 mm x 35 mm, was an inverted hyperplastic polyp (IHP) located in the submucosal layer and consisting mostly of columnar cells resembling foveolar epithelium and pyloric gland cells. Notably, adenocarcinoma with adjacent dysplasia was observed in the submucosal glands. Transition from hyperplasia to dysplasia and from dysplasia to adenocarcinoma was noted. The adenocarcinoma component was intensely and diffusely positive for p53 overexpression, while the dysplasia component showed only weak and focal positivity, suggesting a role of p53 mutation in the dysplasia-carcinoma sequence. Gastric IHP is very rare, and only 31 cases (in 29 patients) have been reported. Five of these IHPs coexisted with gastric adenocarcinomas, which had all developed separately from the IHP lesions. Therefore, this is the first case of adenocarcinoma arising within gastric IHP itself.

Genetic instability and mutation of the TGF-beta-receptor-II gene in ampullary carcinomas

Ampullary carcinomas are relatively rare cancers of which very little is known in terms of carcinogenetic mechanisms at the molecular level. Genetic instability caused by mutations of mismatch-repair genes has been demonstrated to be responsible for hereditary non-polyposis colorectal cancers and a sub-set of sporadic colorectal cancers. In some of those tumors showing genetic instability, the transforming-growth-factor-beta(TGF-beta)-receptor-II gene has been found to be mutated in repetitive sequences and considered to be a target of replication error. We studied the role of genetic instability and associated TGF-beta-receptor-II-gene mutations in a series of 18 sporadic cases by analyzing 5 microsatellite loci (D2S123, D3S1029, D5S409, TP53 and BAT26) and by sequencing a poly-A repeat (nucleotides 709-718) in the TGF-beta-receptor-II gene. Microsatellite instability was observed in 4 (22.2%) and gene mutations in 14 (77.8%) cases. These data indicate that the TGF-beta-receptor-II gene might be a preferential target of genetic instability whose alteration might be specifically advantageous and constitute a common step in the development of ampullary carcinomas.

Inhibition of the mTOR/S6K signal is necessary to enhance fluorouracil-induced apoptosis in gastric cancer cells with HER2 amplification

The purpose of this study was to explore the effect of trastuzumab in enhancing the activity of chemotherapeutic agents and the molecular basis of this effect. Two gastric cancer cell types with HER2 amplification, one sensitive (NCI‑N87) and one insensitive (MKN-7) to trastuzumab, were tested for the effects of trastuzumab on cell growth and cell signaling using MTS assay and western blotting, respectively. Interaction between trastuzumab and chemotherapeutic agents (fluorouracil, doxorubicin, cisplatin and paclitaxel) was evaluated by the combination index (CI). Fluorouracil-induced apoptosis was evaluated using western blot for poly (ADP-ribose) polymerase (PARP). Trastuzumab decreased phosphorylation of S6K, showed synergistic effect with fluorouracil or doxorubicin, and increased fluorouracil-induced apoptosis in NCI-N87 cells, but not in MKN-7 cells. While the mTOR inhibitor everolimus enhanced fluorouracil-induced apoptosis in both HER2-amplified cell lines, this was not the case in the gastric cancer cell lines without HER2 amplification. Consistently, while the EGFR/HER2 inhibitor Cl-387,785 inhibited cell growth of MKN-7, this growth inhibition did not accompany decrease in phosphorylation of S6K, and the compound did not enhance fluorouracil-induced apoptosis. In summary, inhibition of the mTOR/S6K signal may be a key molecular event in enhancing fluorouracil-induced apoptosis specifically in gastric cancer cells with HER2 amplification. mTOR inhibitors may therefore be attractive alternative drugs in gastric cancers with HER2 amplification regardless of their sensitivity to trastuzumab.