Adenomatous Polyposis Coli Gene Promoter Research Articles

Plasma Cell-Free Adenomatous Polyposis Coli Gene Promoter Methylation as a Prognostic Biomarker for Hepatocellular Carcinoma

Introduction: Hepatocellular carcinoma (HCC) is a leading cause of cancer death worldwide. Lack of biomarkers for follow-up after treatment is a clinical challenge. DNA methylation has been proposed to be a potential biomarker in HCC. However, there is still a lack of evidence of its clinical use. This study aimed to evaluate the value of using plasma Adenomatous Polyposis Coli promoter methylation level (APC-MET) as a potential biomarker in HCC treatment. Method: A total of 96 patients with HCC at BCLC stage B who underwent local tumor ablation treatment were prospectively included in this study. APC-MET was examined in the plasma of each patient before and 1 month after treatment. The prediction value of APC-MET for survival outcome and disease status after treatment was analyzed and adjusted with alpha-fetoprotein and protein induced by vitamin K absence-II using Cox regression analysis. Results: Univariate Cox regression analysis showed preoperative APC-MET >0 (HR, 2.9, 95% CI: 1.05–8.05, p = 0.041) and postoperative APC-MET >0 (HR, 3.47, 95% CI: 1.16–10.4, p = 0.026) were both predictors of death, and preoperative APC-MET >0 was a predictor of disease progression after treatment (HR, 2.04, 95% CI: 1.21–3.44, p = 0.007). In multivariate models, preoperative APC-MET >0 was a significant predictor of disease progression after adjusting with the other two traditional biomarkers (HR, 1.82, 95% CI: 1.05–3.17, p = 0.034). Conclusions: Hypermethylation of APC promoter appears to be a potential biomarker that could predict patient survival and disease progression outcomes in patients with intermediate-stage HCC after local ablation treatment.

APC gene promoter methylation as a potential biomarker for lung cancer diagnosis: A meta-analysis.

BackgroundThe aim of this study was to quantitatively analysis the diagnostic performance of adenomatous polyposis coli (APC) gene promoter methylation in serum or sputum/bronchoalveolar lavage fluid (BLAF) as a biomarker for lung cancer identification through pooling of open published data.MethodsThe relevant electronic MEDLINE, EMBASE, Ovid, web of science and CNKI databases were systematically searched to identify the studies related to APC gene promoter methylation for lung cancer diagnosis. Data of true positive (tp), false positive (fp), false negative (fn) and true negative (tn) were extracted from the publications included in the study. The pooled diagnostic sensitivity, specificity and area under summary receiver operating characteristic (SROC) curve (AUC‐SROC) of APC gene promoter methylation were calculated. Publication bias was evaluated by Begg's funnel plot and Egger's line regression test.ResultsFourteen studies associated with APC gene promoter methylation and lung cancer were identified in the databases and finally included in the meta‐analysis. The data was pooled using a random effect model due to significant statistical heterogeneity across the 14 studies (p < 0.05). Using the APC gene promoter methylation as a reference for lung cancer identification, the pooled diagnostic sensitivity and specificity were 0.43 (95% CI: 0.40–0.45), and 0.92 (95% CI: 0.90–0.95), respectively with combined diagnostic positive likelihood ratio (+LR) and negative likelihood ratio (−LR) of 7.15 (95% CI: 3.62–14.12) and 0.63 (95% CI: 0.57–0.71). The pooled diagnostic odds ratio (DOR) and AUC‐SROC of APC gene promoter methylation for lung cancer diagnosis were 9.84 (95% CI: 5.77–16.79) and 0.7, respectively. The Begg's funnel plot and Egger's line regression test both indicated statistical publication bias (t = 5.40, p < 0.05).ConclusionsAPC gene promoter methylation in serum or sputum/BLAF is a potential biomarker for lung cancer diagnosis with high specificity. However, due to its low sensitivity, it may not be suitable for lung cancer screening in the general population.

Association of APC gene promoter methylation and the risk of gastric cancer: A meta-analysis and bioinformatics study.

The methylation status of the adenomatous polyposis coli (APC) promoter has been shown to be associated with the occurrence of gastric cancer, but this finding remains controversial. The aim of this study was to investigate the relationship between methylation of the APC gene promoter and gastric cancer. We searched the Web of Science, EMBASE, Medline, and Cochrane Central Register of Controlled Trials (CENTRAL) databases from the date of creation until August 1, 2019. According to the inclusion criteria, the relationship between the methylation status of the APC gene promoter and gastric cancer was investigated. The incidence of APC promoter methylation in the tissues or blood of patients with and without gastric cancer was compared. The results are expressed as the odds ratio (OR) and 95% confidence interval (CI). The pooled OR of each study was estimated using a fixed effects model or a random effects model to generate forest plots. We further validated the results using the MethHC database. Eight studies (985 samples) were included. Our meta-analysis showed that the incidence of APC promoter methylation in patients with gastric cancer was higher than that of patients without gastric cancer (OR = 3.86, 95% CI 1.71-8.74, P = .001). Methylation of the APC promoter is associated with the incidence of gastric cancer, and it increases the risk of gastric cancer. This study provides a new strategic direction for research on gastric cancer. Methylation of the APC promoter may be a potential biomarker for the diagnosis of gastric cancer, but the results of this work require further confirmation.

Wnt/β‑catenin pathway activation and silencing of the APC gene in HPV‑positive human cervical cancer‑derived cells.

Although persistent infections with high-risk human papilloma virus (HPV) constitute the most significant cofactor for the development of cervical cancer, they are insufficient on their own. Mutations or epigenetic inactivation of the tumor suppressor adenomatous polyposis coli (APC), the two acting as prominent oncogenic mechanisms in a number of types of cancer, are frequently associated with aberrant activation of the Wnt/β-catenin pathway. According to these observations, it was hypothesized that APC alteration may lead to β-catenin deregulation and the abnormal expression of direct targets of the Wnt pathway in HPV-infected cervical cancer cells. The present study confirmed that the stabilization of β-catenin correlates with enhanced transcriptional activity of the β-catenin/T-cell factor complex in cervical cancer cell lines. Sequence analysis of the ‘hot-spot’ in the mutation cluster region did not exhibit genetic alterations that may be associated with APC gene inactivation. In addition, it was identified that there was a good correlation with the hypermethylation status of the APC promoter 1A and the abnormal accumulation of endogenous β-catenin in cell lines and biopsies infected with HPV16, although not HPV18. Removal of the epigenetic markers led to an increase in APC levels and a reduction of β-catenin expression in two transcriptional targets of the Wnt pathway: Matrix metalloproteinase-7 and vascular endothelial growth factor. The present study suggested that the increase in Wnt activity in certain cervical cancer-derived cells may be associated with an alteration in the methylation status of the APC gene promoter 1A.

Correlation between the methylation of APC gene promoter and colon cancer.

The present study was planned to explore the correlation between the methylation of APC (adenomatous polyposis coli) and colon carcinogenesis. Colon cancer tissues and tumor-adjacent normal tissues of 60 colon cancer patients (who received surgical operation in our hospital from January 2012 to December 2014) were collected. SW1116 cells in human colon cancer tissues were selected for culturing. 5-aza-2c-deoxycytidine (5-aza-dC) was utilized as an inhibitor of the methylation for APC gene. Methylation specific PCR (MSP) was utilized for detection of APC methylation in SW1116 cells. The MTT and Transwell assays were performed to detect the effect of the methylation of APC gene on the proliferation and invasive abilities of SW1116 cells. The correlation between the methylation of APC gene and pathological parameters of colon cancer patients was analyzed. MSP results revealed that 41 cases (68.33%) showed methylation of APC gene in colon cancer tissues. No methylation of APC gene was found in tumor-adjacent normal tissues. 5-aza-dC was able to inhibit the methylation of APC gene in SW1116 cells. APC gene methylation was correlated with tumor size, differentiation degree, lymph node metastasis and Dukes staging. In conclusion, the levels of the methylation of APC in colon cancer tissues and SW1116 cells are relatively high. The methylation of APC promoted the proliferation and invasion abilities of SW1116 cells. Furthermore, methylation is correlated with a variety of clinicopathological features of colon cancer patients.

Does adenomatous polyposis coli gene promoter 1A methylation increase non-small cell lung cancer risk? A meta-analysis.

BackgroundThe promoter region of the adenomatous polyposis coli (APC) gene is hypermethylated in several types of cancers, including non‐small cell lung cancer (NSCLC). The prevalence of methylation in the promoter region of this gene in tumor tissues and autologous controls has not been consistent in previous studies. We evaluated the frequency of APC gene promoter 1A methylation between tumor tissues and autologous controls in NSCLC patients by meta‐analysis.MethodsOpen published studies of APC gene promoter 1A methylation between tumor tissues and autologous samples in NSCLC patients were identified using a systematic search. Odds ratios (OR) and 95% confidence intervals (CI) of APC gene promoter 1A methylation in lung cancer tissues versus autologous controls were calculated. Fourteen studies, involving a total of 1345 patients and 2182 samples, were finally included.ResultsThe pooled proportion of APC promoter 1A methylation was 0.62 (95% CI 0.52–072) and 0.34 (95% CI 0.21–0.50) in cancer tissues and autologous controls, respectively. The APC gene promoter 1A methylation rate in cancer tissues was much higher than in autologous controls, with a pooled OR of 3.66 (95% CI 2.12–6.33). A strong and significant correlation of APC gene promoter 1A methylation between tumor tissues and autologous controls was detected (correlation coefficient rpearson = 0.77; P = 0.0013).ConclusionThe proportion of APC promoter 1A methylation in lung cancer tissues was higher than in autologous controls, indicating that promoter 1A methylation of the APC gene may play an important role in NSCLC carcinogenesis.

Association of APC, GSTP1 and SOCS1 promoter methylation with the risk of hepatocellular carcinoma: a meta-analysis.

Studies of the relationships of adenomatous polyposis coli (APC), glutathione-S-transferase P1 (GSTP1) and suppressor of the cytokine signalling 1 (SOCS1) promoter region methylation with the risk of hepatocellular carcinoma (HCC) have yielded inconsistent results. We carried out the current meta-analysis to comprehensively assess the associations between APC, GSTP1 and SOCS1 promoter methylation frequency and the risk of HCC. All relevant reports were identified by searching the PubMed, Embase, Web of Science, CNKI and the Chinese BioMedical Literature databases before 1 March 2014, with restriction to articles published in the Chinese and English languages. Pooled odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were calculated to investigate the rates of APC, GSTP1 and SOCS1 promoter methylation and the risk of HCC. Our meta-analysis identified relationships of APC (12 studies with 592 HCC tumour tissues), GSTP1 (14 studies including 646 HCC tumour tissues) and SOCS1 (11 studies with 512 HCC tumour tissues) promoter methylation with the risk of HCC. Compared with paracancerous tissues, the pooled ORs of APC, GSTP1 and SOCS1 promoter region methylation in HCC cancer tissues were 5.32 (95% CI=2.96-9.56), 5.65, (95% CI=3.41-9.35) and 2.73 (95% CI=1.37-5.44), respectively. Compared with normal liver tissues as controls, the pooled ORs of APC, GSTP1 and SOCS1 promoter region methylation in HCC cancer tissues were 20.43 (95% CI=5.56-75.08), 18.78 (95% CI=5.76-61.19) and 13.00 (95% CI=5.20-32.47), respectively. Subgroup analysis by ethnicity showed that APC, GSTP1 and SOCS1 promoter methylation was associated significantly with the risk of HCC in both Asian and White populations (all P<0.05). Our meta-analysis suggested strong associations between APC, GSTP1 and SOCS1 gene promoter methylation and the risk of HCC, suggesting these to be promising biomarkers for HCC.

Analysis of APC and IGFBP7 promoter gene methylation in Swedish and Vietnamese colorectal cancer patients

The tumour suppressor gene adenomatous polyposis coli (APC) is a key component that drives colorectal carcinogenesis. The reported DNA methylation in the promoter of APC varies greatly among studies of colorectal cancer (CRC) in different populations. Insulin-like growth factor binding protein 7 (IGFBP7), also known as IGFBP-related protein 1 (IGFBP-rP1), is expressed in various tissue types, including the lung, brain, prostate and gastrointestinal tract, and has been suggested to play a tumour suppressor role against colorectal carcinogenesis. Studies have indicated that IGFBP7 is inactivated by DNA methylation in human colon, lung and breast cancer. In the present study, we used the methylation-specific polymerase chain reaction to study the methylation status of the APC and IGFBP7 gene promoters in cancerous and paired normal tissue to evaluate its impact on clinical factors and association with ethnicity, represented by Swedish and Vietnamese CRC patients. We also investigated the distribution of CpG islands and the CpG dinucleotide density of each CpG island in the regions which were the subject of our investigation. Overall, normal tissue from Swedish patients exhibited a significantly higher frequency of IGFBP7 gene methylation in comparison with that of Vietnamese patients. Moreover, a significantly higher number of cancer tissues from Vietnamese individuals showed higher levels of methylation versus the paired normal tissue compared with that of Swedish patients. When we studied the methylation in cancer compared with the matched normal tissue in individuals, we found that a significantly higher number of Vietnamese patients had a higher degree of IGFBP7 gene methylation in cancer versus matched normal tissue in comparison with Swedish patients. Taken together, our results suggest that the methylation of the APC and IGFBP7 gene promoter region in cancerous tissue, in combination with the predominance of methylation in normal tissue, may serve as a prognostic factor in CRC patients.

Hypermethylation of adenomatous polyposis coli gene promoter is associated with novel Wnt signaling pathway in gastric adenomas

Gastric adenomas (GAs) are considered as premalignant lesions of gastric adenocarcinoma. The role of Wnt signaling pathway in GAs is rarely identified. In the present study, we aimed to determine whether Wnt signaling plays a role in the pathogenesis of GAs, and to clarify the mechanism of Wnt signaling in GAs. The study investigated the relationship between clinicopathological characteristics, Helicobacter pylori (Hp) infection, adenomatous polyposis coli (APC) promoter methylation, APC and β-catenin immunohistochemistry expression and mutation status, compared with 38 gastric adenoma and periadenomatous tissues (PTs). The abnormal expression of β-catenin in PTs, low-grade adenomas (LGAs) and high-grade adenomas (HGAs) was 0%, 9.09% and 81.25%. For APC, immunoreactive score (IRS) was 5.50 ± 0.5 in PTs, 3.59 ± 1.4 in LGAs and 1.8 ± 2.0 in HGAs. The scores in LGAs and HGAs were significantly lower than those in PTs (P = 0.000). IRS reflected significantly reduced expression of APC in HGAs (P = 0.002). The absent expression of APC had a correlation with the expression of β-catenin (P = 0.000). Four LGAs (18.18%) and nine HGAs (56.25%) had methylation of APC. APC promoter methylation correlated with the grade (P = 0.014) and the expression of β-catenin and APC (P = 0.000). Genes mutation was detected in only two adenomas (5.3%). The presence of Hp in HGAs (43.8%) was significantly higher than in LGAs (13.6%) (P = 0.038). But there was no statistical correlation to growth pattern, size, APC hypermethylation and gene mutation. Hypermethylation of APC promoter, instead of mutations involving APC and β-catenin, may play a role in the development and progression of GAs contributing to moderate activation of Wnt signaling. Helicobacter pylori may accelerate the progress of gastric adenoma, but the pathogenesis needs further research.

Aberrant methylation of the Adenomatous Polyposis Coli (APC) gene promoter is associated with the inflammatory breast cancer phenotype

Aberrant methylation of the adenomatous polyposis coli (APC) gene promoter occurs in about 40% of breast tumours and has been correlated with reduced APC protein levels. To what extent epigenetic alterations of the APC gene may differ according to specific breast cancer phenotypes, remains to be elucidated. Our aim was to explore the role of APC methylation in the inflammatory breast cancer (IBC) phenotype. The status of APC gene promoter hypermethylation was investigated in DNA from normal breast tissues, IBC and non-IBC by both conventional and real-time quantitative methylation-specific PCR (MSP). APC methylation levels were compared with APC mRNA and protein levels. Hypermethylation of the APC gene promoter was present in 71% of IBC samples (n=21) and 43% of non-IBC samples (n=30) by conventional MSP (P=0.047). The APC gene also showed an increased frequency of high methylation levels in IBC (in 74% of cases, n=19) vs non-IBC (in 46% of cases, n=35) using a qMSP assay (P=0.048). We observed no significant association between APC methylation levels by qMSP and APC mRNA or protein expression levels. In conclusion, for the first time, we report the association of aberrant methylation of the APC gene promoter with the IBC phenotype, which might be of biological and clinical importance.

Methylation of the adenomatous polyposis coli (APC) gene in human placenta and hypermethylation in choriocarcinoma cells

Methylation of the human APC gene promoter is associated with several different types of cancers and has also been documented in some pre-cancerous tissues. We have examined the methylation of APC gene promoters in human placenta and choriocarcinoma cells. This revealed a general hypomethylation of the APC-1b promoter and a pattern with monoallelic methylation of the APC-1a promoter in full term placental tissue. However, there was no evidence of a parent-of-origin effect, suggesting random post zygotic origin of methylation. Increased methylation of this promoter was observed in all choriocarcinoma-derived trophoblast cell lines, suggesting a trophoblastic origin of placental APC methylation and implicating APC hypermethylation in the development of this group of gestational tumours. Our demonstration of placental methylation of the APC-1a promoter represents the first observation of monoallelic methylation of this gene in early development, and provides further support for a role of canonical Wnt signalling in placental trophoblast invasiveness. This also implicates tumour suppressor gene silencing as an integral part of normal human placental development.

Study of the methylated CpG status of adenomatous polyposis coli gene promoter 1A sequence on lung cancer

目的 探寻结肠多发性腺瘤样息肉(APC)基因启动子1A序列中肺癌甲基化位点及其存在模式.方法用甲基化序列特异性引物,对阳性控制样品(CB+)、阴性控制样品(CB-)、13份正常肺组织及19份肺癌组织进行APC基因启动子1A序列甲基化特异性扩增(MSP),其扩增产物直接测序和进行克隆测序分析.结果在19份肺癌组织中,APC基因启动子1A序列的707、714、719和726位点发生高甲基化,甲基化率分别为95%(18/19)、74%(14/19)、74%(14/19)和74%(14/19),与正常肺组织比较,差异均有统计学意义(P＜0.001).而679和687位点甲基化发生率均为11%(2/19),与正常肺组织甲基化发生率(0/13)接近(P＞0.05).结论在APC基因启动子1A序列中存在CpG胞嘧啶二核苷酸特定甲基化模式,其对肺癌早期诊断可能有重要意义。

7,12-Dimethylbenzanthracene-dependent transcriptional regulation of adenomatous polyposis coli (APC) gene expression in normal breast epithelial cells is mediated by GC-box binding protein Sp3

In the present investigation, we have examined the transcriptional regulation of adenomatous polyposis coli (APC) gene expression in the spontaneously immortalized human normal breast epithelial cell line, MCF10A, in response to carcinogen 7,12-dimethylbenz(a)anthracene (DMBA) treatment. The APC mRNA levels and the APC gene's promoter (pAPCP) activity were increased in MCF10A cells after treatment with DMBA. A sequential deletion analysis and site-directed mutagenesis of the pAPCP promoter revealed that the DMBA response is mediated through a GC-box element. Also, the GC-box binding agent mithramycin A, which prevents binding of proteins to the GC-box region, abolished DMBA-mediated increase of the pAPCP promoter activity. The specificity of the proteins binding to the GC-box region was characterized by gel-shift analysis. An increased binding of the GC-box binding proteins was observed in the gel-shift analysis with nuclear extracts from DMBA-treated MCF10A cells, which corresponded to the increased levels of Sp1 and Sp3 proteins. However, a super-shift of the DNA-protein complexes was observed with only anti-Sp3 antibody. Based on the chromatin-immunoprecipitation assay results, the Sp3 appeared to be a genuine protein binding to the GC-box site of the pAPCP promoter. In RNA interference experiments, in which the Sp3 expression was knocked down, the DMBA response on the pAPCP promoter activity was reduced, suggesting that the binding of Sp3 to the GC-box site is critical for DMBA-induced pAPCP promoter activity. From these results we conclude that the increased pAPCP promoter activity in the MCF10A cell line in response to DMBA treatment is mediated by Sp3.

Novel adenomatous polyposis coli gene promoter is located 40 kb upstream of the initiating methionine

The product of the oncosuppressor adenomatous polyposis coli ( APC) gene is involved in cell cycle arrest and apoptosis and its loss of function is associated with the development of colorectal carcinogenesis. Its transcriptional regulation seems rather complex and has not been completely elucidated up to now. In an attempt to identify the transcription start sites for the mouse Apc gene we have detected a novel transcript in mouse embryonic stem (ES) cells and colon tissue. This transcript contains an untranslated exon, whose flanking sequences exhibited strong promoter activity in transient transfection experiments. These results suggest that we have identified a novel promoter for the mouse Apc gene, localized about 40 kb upstream of the initiating methionine, which drives expression of the unique Apc transcript type detected in undifferentiated totipotent ES cells. Transcripts bearing the novel exon combined either with exon 1 or with exon 2 were detected in all mouse tissues tested.

APC, beta-catenin, and E-cadherin and the development of recurrent endometrial carcinoma.

Endometrial carcinoma, generally, has a good prognosis. However, in some patients, the tumor appears to behave very aggressively, a course that cannot be explained with histopathological characteristics. More insight into the molecular background can be valuable to clarify these differences in tumor behavior. The three components associated with the Wnt pathway--i.e., adenomatous polyposis coli (APC), beta-catenin, and E-cadherin--were evaluated in a case-control study of 28 patients with stage-I endometrial carcinomas to determine their involvement in the development of recurrent disease. Mutation analysis of the mutation cluster region of the APC gene, determination of gene promoter methylation status of the APC-1A and E-cadherin genes, and immunohistochemical analysis of APC, E-cadherin, and beta-catenin were performed using paraffin-embedded tumor tissue. Twenty-one APC gene mutations were detected in 12 of 28 (43%) patients. Only three mutations would result in a stopcodon in the APC gene. APC gene promoter methylation was assessed in 12 of 28 (43%) patients. APC immunostaining was absent in two of 24 (8.3%) patients. The occurrence of APC mutations, APC gene promoter methylation, and APC immunostaining were not predictive for recurrence. No E-cadherin expression was observed in four of 24 patients (17%). E-cadherin gene promoter methylation could not be detected in any of the patients. The absence of E-cadherin expression was predictive for distant metastases, but not for local recurrence. Nuclear localization of beta-catenin was present in nine of 24 (38%) patients and was not predictive for recurrent disease. Involvement of epigenetic and genetic aberrations in APC and beta-catenin genes seems to be of minor importance for the development of local recurrences and distant metastases. Although the number of patients is limited, E-cadherin expression appears to be predictive for the development of distant metastases in endometrial carcinoma.

APC, β-catenin, and E-cadherin and the development of recurrent endometrial carcinoma

Endometrial carcinoma, generally, has a good prognosis. However, in some patients, the tumor appears to behave very aggressively, a course that cannot be explained with histopathological characteristics. More insight into the molecular background can be valuable to clarify these differences in tumor behavior. The three components associated with the Wnt pathway – i.e., adenomatous polyposis coli (APC), β-catenin, and E-cadherin – were evaluated in a case-control study of 28 patients with stage-I endometrial carcinomas to determine their involvement in the development of recurrent disease. Mutation analysis of the mutation cluster region of theAPCgene, determination of gene promoter methylation status of theAPC-1AandE-cadheringenes, and immunohistochemical analysis of APC, E-cadherin, and β-catenin were performed using paraffin-embedded tumor tissue. Twenty-oneAPCgene mutations were detected in 12 of 28 (43%) patients. Only three mutations would result in a stopcodon in theAPCgene.APCgene promoter methylation was assessed in 12 of 28 (43%) patients. APC immunostaining was absent in two of 24 (8.3%) patients. The occurrence ofAPCmutations,APCgene promoter methylation, and APC immunostaining were not predictive for recurrence. No E-cadherin expression was observed in four of 24 patients (17%).E-cadheringene promoter methylation could not be detected in any of the patients. The absence of E-cadherin expression was predictive for distant metastases, but not for local recurrence. Nuclear localization of β-catenin was present in nine of 24 (38%) patients and was not predictive for recurrent disease. Involvement of epigenetic and genetic aberrations inAPCand β-cateningenes seems to be of minor importance for the development of local recurrences and distant metastases. Although the number of patients is limited, E-cadherin expression appears to be predictive for the development of distant metastases in endometrial carcinoma.

Adenomatous polyposis coli (APC) gene promoter hypermethylation in primary breast cancers.

Similar to findings in colorectal cancers, it has been suggested that disruption of the adenomatous polyposis coli (APC)/β-catenin pathway may be involved in breast carcinogenesis. However, somatic mutations of APC and β- catenin are infrequently reported in breast cancers, in contrast to findings in colorectal cancers. To further explore the role of the APC/β-catenin pathway in breast carcinogenesis, we investigated the status of APC gene promoter methylation in primary breast cancers and in their non-cancerous breast tissue counterparts, as well as mutations of the APC and β- catenin genes. Hypermethylation of the APC promoter CpG island was detected in 18 of 50 (36%) primary breast cancers and in none of 21 non-cancerous breast tissue samples, although no mutations of the APC and β- catenin were found. No significant associations between APC promoter hypermethylation and patient age, lymph node metastasis, oestrogen and progesterone receptor status, size, stage or histological type of tumour were observed. These results indicate that APC promoter CpG island hypermethylation is a cancer-specific change and may be a more common mechanism of inactivation of this tumour suppressor gene in primary breast cancers than previously suspected. © 2001 Cancer Research Campaign http://www.bjcancer.com

Adenomatous polyposis coli gene promoter hypermethylation in non-small cell lung cancer is associated with survival.

Methylation of 5' CpG islands in promoter and upstream coding regions has been identified as a mechanism for transcriptional inactivation of tumor suppressor genes. The purpose of this study was to determine whether hypermethylation of the adenomatous polyposis coli (APC) gene promoter occurs in primary non-small cell lung cancer (NSCLC), and whether hypermethylated APC has any relationship with survival. APC promoter 1A methylation was determined in normal and corresponding tumor tissue from 91 NSCLC patients and in a control group of 10 patients without cancer, using a quantitative fluorogenic real-time PCR (Taqman) system. APC promoter methylation was detectable in 86 (95%) of 91 tumor samples, but also in 80 (88%) of 91 normal samples of NSCLC patients, and in only two (20%) of 10 normal lung tissues of the control group. The median level of APC promoter methylation was 4.75 in tumor compared to 1.57 in normal lung tissue (P<0.001). Patients with low methylation status showed significantly longer survival than did patients with high methylation status (P=0.041). In a multivariate analysis of prognostic factors, APC methylation was a significant independent prognostic factor (P=0.044), as were pT (P=0.050) and pN (P<0.001) classifications. This investigation shows that APC gene promoter methylation occurs in the majority of primary NSCLCs. High APC promoter methylation is significantly associated with inferior survival, showing promise as a biomarker of biologically aggressive disease in NSCLC.

Distinct methylation patterns of two APC gene promoters in normal and cancerous gastric epithelia.

The adenomatous polyposis coli (APC) tumor suppressor gene is mutationally inactivated in both familial and sporadic forms of colorectal cancers. In addition, hypermethylation of CpG islands in the upstream portion of APC, a potential alternative mechanism of tumor suppressor gene inactivation, has been described in colorectal cancer. Because a subset of both gastric and colorectal cancers display the CpG island methylator phenotype, we hypothesized that epigenetic inactivation of APC was likely to occur in at least some gastric cancers. APC exhibits two forms of transcripts from exons 1A and 1B in the stomach. Therefore, we investigated CpG island methylation in the sequences upstream of exons 1A and 1B, i.e., promoters 1A and 1B, respectively. We evaluated DNAs from 10 gastric cancer cell lines, 40 primary gastric cancers, and 40 matching non-cancerous gastric mucosae. Methylated alleles of promoter 1A were present in 10 (100%) of 10 gastric cancer cell lines, 33 (82.5%) of 40 primary gastric cancers, and 39 (97.5%) of 40 noncancerous gastric mucosae. In contrast, promoter 1B was unmethylated in all of these same samples. APC transcripts from exon 1A were not expressed in nine of the 10 methylated gastric cancer cell lines, whereas APC transcripts were expressed from exon 1B. Thus, expression from a given promoter correlated well with its methylation status. We conclude that in contrast to the colon, methylation of promoter 1A is a normal event in the stomach; moreover, promoter 1B is protected from methylation in the stomach and thus probably does not participate in this form of epigenetic APC inactivation.