Association between Cyclooxygenase expression and colorectal adenoma characteristics

The cyclooxygenase (COX) pathway is important in colorectal carcinogenesis with the majority of cancers overexpressing COX-2; however, the role of COX-2 in the development of colorectal adenomas is less well defined. Accordingly, we analyzed 108 colorectal adenomas for COX-1 and COX-2 transcription in archival formalin-fixed, paraffin-embedded tissue using by real-time PCR and normalized to beta-actin. Neither COX-1 nor COX-2 mRNA expression differed with regard to age or gender of the subject. COX-2 mRNA expression was significantly higher in distal adenomas (2.2 +/- 1.9) compared with proximal (0.7 +/- 0.5) adenomas (P < 0.0001) and in larger (>/=7 mm) compared with smaller (<7 mm) adenomas (2.3 +/- 2.2 and 1.7 +/- 1.3, respectively, P = 0.04). COX-2 expression did not differ significantly in tubular compared with tubulovillous adenomas, although there appeared to be a trend toward higher COX-2 expression in tubulovillous adenomas with increasing villous content. Additionally, there was not a significant difference in either COX-1 or COX-2 based on the degree of dysplasia Therefore, if COX-2 inhibitors work through a COX-2 mechanism, these agents may have differential effects on colorectal adenomas that are distal and larger.

Thymidylate synthase expression in advanced colorectal cancer predicts for response to raltitrexed

PURPOSE

The purpose of this research was to evaluate the predictive value of expression of thymidylate synthase (TS) and other genes for response to raltitrexed (RTX).

EXPERIMENTAL DESIGN

Twenty-five patients with metastatic colorectal cancer received RTX 3 mg/m(2) 3-weekly. Pretreatment tumor biopsies were analyzed for TS, dihydropyrimidine dehydrogenase (DPD), thymidine phosphorylase (TP), folylpolyglutamate synthetase, and reduced folate carrier mRNA expression by real-time reverse transcription-PCR. TS protein expression was evaluated by immunohistochemistry using a polyclonal TS antibody.

RESULTS

Twenty patients were evaluable for response and gene expression. Six of 20 (30%) achieved a partial response. Median TS/beta-actin was 5.7 x 10(3) (range, 2.2-42 x 10(3)). Median TS/beta-actin was 3.7 x 10(3) in responding patients and 6.1 x 10(3) in nonresponders (P = 0.048). Five of 6 patients with TS/beta-actin </=4.1 x 10(3) and 1 of 14 with higher values responded (P = 0.002). Overall survival was 21.7 months in patients with TS/beta-actin </=4.1 x 10(3) and 5.7 months in patients with higher values (P = 0.013). No correlations were seen between expression of TP, DPD, reduced folate carrier, or folylpolyglutamate synthetase mRNA and response or survival. Weak TS staining was seen in 10 of 21 tumors evaluable for immunohistochemistry, including 5 responders All 4 of the patients with both weak staining and TS/beta-actin </=4.1 x 10(3) responded.

CONCLUSIONS

High TS mRNA expression predicts nonresponse to RTX. By contrast with 5-fluorouracil, high levels of TP and DPD mRNA are not associated with RTX resistance. Limited genomic fingerprinting could optimize single-agent therapy, allowing combinations to be reserved for high TS-expressing patients or for treatment failures, with potential reductions in toxicity and cost.

Vascular endothelial growth factor and basic fibroblast growth factor expression in esophageal adenocarcinoma and Barrett esophagus

OBJECTIVE

This study was undertaken to investigate the role of the angiogenic factors vascular endothelial growth factor and basic fibroblast growth factor in the development and progression of Barrett esophagus and adenocarcinomas of the esophagus and gastroesophageal junction.

METHODS

Vascular endothelial growth factor and basic fibroblast growth factor messenger RNA expression levels, relative to the control gene encoding beta-actin, were measured by using a quantitative reverse transcription-polymerase chain reaction method (ABI 7700 Sequence Detector system) in specimens of Barrett intestinal metaplasia (n = 16), dysplasia (n = 11), adenocarcinoma (n = l 5), and matching normal squamous esophageal tissues (n = 35). Vascular endothelial growth factor and basic fibroblast growth factor protein expression and CD31(+) microvessel density were assessed by means of immunohistochemistry in 25 tissue sections that included representative areas for each of these Barrett stages.

RESULTS

Expression levels were significantly increased in adenocarcinoma compared with in either normal squamous mucosa (P <.0001 for both genes) or intestinal metaplasia (vascular endothelial growth factor, P =.002; basic fibroblast growth factor, P <.0001). Vascular endothelial growth factor levels were also significantly higher in cancer tissues compared with dysplasia tissues (P =.024, Mann-Whitney U test). Basic fibroblast growth factor expression was also significantly increased in Barrett dysplastic mucosa compared with in intestinal metaplasia or normal esophageal mucosa. Microvessel density was generally higher in adenocarcinoma compared with in preneoplastic Barrett tissues. The pattern of vascular endothelial growth factor and basic fibroblast growth factor protein expression was similar to the messenger RNA expression pattern, with the exception that mucin-containing goblet cells stained intensely for vascular endothelial growth factor and only weak vascular endothelial growth factor staining was present in some adenocarcinomas.

CONCLUSIONS

Vascular endothelial growth factor and basic fibroblast growth factor messenger RNA expression levels are significantly upregulated in esophageal and gastroesophageal junction adenocarcinomas, suggesting a role for these angiogenic factors in the development of these cancers. Vascular endothelial growth factor and basic fibroblast growth factor messenger RNA expression levels are also increased in some Barrett esophagus tissues, with this increase occurring at an earlier stage for basic fibroblast growth factor than for vascular endothelial growth factor. Basic fibroblast growth factor protein expression pattern is similar to the messenger RNA expression pattern, but unlike the messenger RNA findings, vascular endothelial growth factor protein expression is strongest in goblet cells.

Quantitative O(6)-methylguanine DNA methyltransferase methylation analysis in curatively resected non-small cell lung cancer: associations with clinical outcome

PURPOSE

Hypermethylation of the O(6)-methylguanine DNA methyltransferase (MGMT) promoter region leads to transcriptional repression of the MGMT gene and is a common event in primary human neoplasia. The purpose of this study was to determine the frequency and clinical relevance of MGMT gene promoter hypermethylation in curatively resected non-small cell lung cancer (NSCLC).

EXPERIMENTAL DESIGN

MGMT hypermethylation, expressed as the ratio between methylated MGMT to unmethylated MYOD1 in genomic DNA, was analyzed in normal and matching tumor tissue from 90 patients with NSCLC, and a control group of 10 patients without cancer using a methylation-specific fluorogenic Real-Time PCR (Taqman) system.

RESULTS

Hypermethylation of the MGMT promoter was detected in 34 of 90 (38%) tumor specimens and 16 of 90 (18%) matching normal lung tissues of patients with NSCLC, and in 0 (0%) cases of the control group without lung cancer. The mean MGMT methylation level was significantly higher in tumor than in matching normal tissue (P < 0.001). MGMT methylation in normal tissue was always accompanied with MGMT methylation in matching tumor tissue. Patients without MGMT promoter hypermethylation showed a significantly better survival than patients with MGMT promoter hypermethylation (P = 0.017). Multivariate analysis revealed MGMT promoter methylation as an independent unfavorable prognostic factor (P = 0.030).

CONCLUSIONS

MGMT promoter hypermethylation is a common event in patients with primary NSCLC. This epigenetic alteration is associated with inferior survival, suggesting that MGMT promoter hypermethylation might be an important biomarker for a biological aggressive disease in NSCLC.

Functional polymorphism of the thymidylate synthase gene in colorectal cancer accompanied by frequent loss of heterozygosity

The thymidylate synthase (TS) gene has a polymorphic repeated sequence in its 5'-untranslated region. The repeat length is associated with TS protein expression, which suggests that we may be able to predict the efficacy of 5-fluorouracil (5-FU)-based chemotherapy from a patient's TS genotype determined through analysis of normal tissue obtained non-invasively. However, it is not yet elucidated whether the TS genotype is identical in tumor and normal tissue. In this study, we investigated the TS genotype in 151 matched tumor and normal DNA samples isolated from colorectal cancer and adjacent normal tissues by PCR analysis. The results showed that TS genotypes are identical in normal and tumor tissues of homozygous individuals, suggesting that the repeat sequence is stable through carcinogenesis. However, in heterozygous samples, an imbalance between the 2R and 3R alleles in the tumor DNA was frequently observed, suggesting loss of heterozygosity (LOH) at the TS locus. Detailed LOH analysis revealed that 62% (31 of 50) of 2R/3R-heterozygous samples had LOH. Frequent LOH at the TS locus was confirmed by RT-PCR of TS mRNA and microsatellite analysis using the marker D18S59, located on 18p11.3. There was no difference in the expressions of TS mRNA and TS protein between LOH and non-LOH samples. However, when the heterozygous genotype bearing LOH was subdivided according to the number of repeats, the cancer tissue with 2R/loss genotype expressed a significantly lower level of TS protein than did that with 3R/loss genotype. The results suggest that the difference in TS genotype between tumor and normal tissue due to LOH should be considered when the genotype is analyzed with normal tissue, such as peripheral blood cells, because it is important for TS protein expression.

Low ERCC1 expression correlates with prolonged survival after cisplatin plus gemcitabine chemotherapy in non-small cell lung cancer

PURPOSE

Overexpression of the excision repair cross-complementing 1 (ERCC1) gene, which is crucial in the repair of cisplatin (CDDP)-DNA adducts, is reported to negatively influence the effectiveness of CDDP-based therapy for gastric and ovarian cancers. Recent evidence indicates that Gemcitabine (Gem) may modulate ERCC1 nucleotide excision repair activity, and down-regulation of DNA repair activity by ERCC1 antisense RNA reportedly inhibits synergism of CDDP/Gem. We investigated whether ERCC1 mRNA expression levels were associated with clinical outcomes after treatment with a combination Gem/CDDP regimen for patients with advanced stage non-small cell lung cancer (NSCLC).

EXPERIMENTAL DESIGN

Response and survival were correlated with the level of ERCC1 expression in 56 patients with advanced (stage IIIb or IV) NSCLC treated as part of a multicenter randomized trial with Gem 1250 mg/m(2) days 1 and 8 plus CDDP 100 mg/m(2) on day 1 every 3 weeks. mRNA was isolated from paraffin-embedded pretreatment primary tumor specimens, and relative expression levels of ERCC1/beta-actin were measured using a quantitative reverse transcription-PCR (Taqman) system.

RESULTS

ERCC1 expression was detectable in all tumors. There were no significant differences in ERCC1 levels by gender, age, performance status, weight loss, or tumor stage. The overall response rate was 44.7%. There were no significant associations between ERCC1 expression and response. Median overall survival was significantly longer in patients with low ERCC1 expression tumors (61.6 weeks; 95% confidence interval, 42.4-80.7 weeks) compared to patients with high expression tumors (20.4 weeks, 95% confidence interval, 6.9-33.9 weeks). ERCC1 expression, Eastern Cooperative Oncology Group performance status, and presence of weight loss were significant prognostic factors for survival in a Cox proportional hazards multivariable analysis.

CONCLUSIONS

These data suggest that ERCC1 expression is a predictive factor for survival after CDDP/Gem therapy in advanced NSCLC. Although there was a trend toward decreased response with high ERCC1 mRNA levels, this difference failed to reach statistical significance. This result may reflect the impact of Gem and the requirement for ERCC1 expression for CDDP/Gem synergism or may be attributable to the relatively small patient sample size in this study. Prospective studies of ERCC1 as a predictive marker for activity of CDDP-based regimens in NSCLC are warranted.

Glutathione S-transferase-pi expression is downregulated in patients with Barrett's esophagus and esophageal adenocarcinoma

The glutathione S-transferases (GSTs) are a family of enzymes that play an important role in the prevention of cancer by detoxifying numerous potentially carcinogenic compounds. GSTs conjugate reduced glutathione to a variety of electrophilic and hydrophobic compounds, converting them into more soluble, more easily excretable compounds. Decreased glutathione S-transferase-pi (GSTPI) enzyme activity has been reported in Barrett's esophagus, and an inverse correlation was demonstrated between GST enzyme activity and tumor incidence in the gastrointestinal tract, but the role of GSTPI messengerRNA (mRNA) expression in Barrett's esophagus and associated adenocarcinomas is uncertain. The purpose of this study was to investigate the role of GSTPI mRNA and protein expression in the development and progression of the Barrett's metaplasia-dysplasia-adenocarcinoma sequence, and to investigate the potential of GSTPI quantitation as a biomarker in the clinical management of this disease. GSTPI mRNA expression levels, in relation to the housekeeping gene beta-actin, were analyzed using a quantitative real-time reverse transcription-polymerase chain reaction method (TaqMan) in 111 specimens from 19 patients with Barrett's esophagus without carcinoma (BE group), 21 patients with Barrett's-associated adenocarcinoma (EA group), and a control group of 10 patients without evidence of Barrett's esophagus or chronic gastroesophageal reflux disease. GSTPI mRNA expression was detectable in all 111 samples investigated. Analyzed according to histopathologic group, the median GSTPI mRNA expression was highest in normal squamous esophagus epithelium, intermediate in Barrett's esophagus, and lowest in adenocarcinoma tissues (P < 0.001). The median GSTPI expression was significantly decreased in Barrett's esophagus tissues compared to matching normal squamous esophagus from either the BE group (P = 0.001) or the EA group (P = 0.023). GSTPI expression levels in adenocarcinoma tissues were decreased compared to matching normal esophagus tissues from the patients with adenocarcinoma (P = 0.011). Furthermore, GSTPI mRNA expression values were significantly different between metaplastic, dysplastic, and adenocarcinoma tissues (P = 0.026). GSTPI expression levels were also significantly lower in histologically normal squamous esophagus tissues from patients with cancer (EA group) compared to both normal esophagus tissues from patients without cancer (BE group; P = 0.007) and normal esophagus tissues from the control group with no esophageal abnormality (P = 0.002). GSTPI protein expression was generally highest in the basal layer of normal squamous esophagus epithelium and lowest in adenocarcinoma cells, with Barrett's cells showing intermediate staining intensity. Our results show that downregulation of GSTPI expression is an early event in the development of Barrett's esophagus and esophageal adenocarcinoma. Loss of GSTPI expression may have an important role in the development and progression of this disease.

Biochemical and molecular effects of UCN-01 in combination with 5-fluorodeoxyuridine in A431 human epidermoid cancer cells

Concurrent and pre-exposure of A431 human epidermoid cancer cells to UCN-01, an investigational anticancer drug, with 5-fluoro--2'-deoxyuridine (FdUrd), which targets thymidylate synthase, produced more than additive cytotoxicty. A 24-h exposure to 10 nM FdUrd led to inhibition of TS, a 2.5-fold increase in total thymidylate synthase protein content, profound dTTP depletion and a 6.3-fold increase in the ratio of dATP to dTTP, but did not cause single-strand breaks in DNA. However, FdUrd enhanced UCN-01-associated DNA strand breaks. Concurrent thymidine exposure led to repletion of dTTP pools, and cytoprotection against FdUrd alone and with UCN-01. UCN-01 arrested cells in G1, decreased the percentage of FdUrd-treated cells in S phase and reduced FdUrd-DNA incorporation, suggesting the latter was not important for cytotoxicity. Delayed induction of high molecular mass DNA fragmentation and poly(ADP-ribose) polymerase cleavage was observed with the combination of UCN-01 and FdUrd. These findings suggest that while FdUrd-mediated deoxynucleotide imbalance alone was insufficient to induce apoptosis in this p53-mutant cell line, it magnified UCN-01's effects, most likely by interfering with DNA repair. The clinical evaluation of UCN-01 combined with 5-fluoropyrimidines may be of interest.

Prognostic significance of cyclooxygenase 2 mRNA expression in non-small cell lung cancer

OBJECTIVE

To investigate cyclooxygenase-2 (COX-2) mRNA expression in curatively resected non-small cell lung cancer (NSCLC) and to determine its association with prognosis.

SUMMARY BACKGROUND DATA

Lung cancer is one of the most common malignancies in the world. Despite improvements in the diagnosis and treatment of NSCLC, the 5-year survival rate remains less than 15%. Identification of prognostic predictors based on molecular alterations could lead to additional diagnostic tools and eventually to more effective therapeutic options. Overexpression of COX-2 has been reported in several human malignancies, including lung cancer, but the prognostic importance of this overexpression has not been elucidated.

METHODS

COX-2 mRNA expression was analyzed using a quantitative real-time polymerase chain reaction (Taqman) method in surgically resected tumor specimens from 89 patients with curatively resected NSCLC.

RESULTS

COX-2 mRNA was detectable in all 89 (100%) tumor tissues. High COX-2 expression in tumors was significantly associated with inferior survival. Multivariate analysis showed that high COX-2 expression is an independent predictor of worse survival in patients with NSCLC.

CONCLUSIONS

High COX-2 mRNA expression is an important biomarker for biologically aggressive disease in NSCLC and might be helpful in identifying patients who would benefit from additional therapies for controlling their disease.

The role of retinoid X receptor messenger RNA expression in curatively resected non-small cell lung cancer

BACKGROUND

Retinoid X receptors (RXRs) have inhibitory effects on non-small cell lung cancer (NSCLC) cell growth, and RXRbeta expression is reduced in NSCLC specimens compared with normal lung tissue. We hypothesized that suppressed RXR expression might be a prognostic factor of worse clinical outcome in patients with NSCLC.

EXPERIMENTAL DESIGN

Using a quantitative real-time reverse transcription-PCR (TaqMan) method, we analyzed RXRalpha, RXRbeta, and RXRgamma mRNA expression in normal lung tissue and matching tumor samples from 88 patients with NSCLC.

RESULTS

The median mRNA expression levels of all three RXR subtypes were frequently decreased in tumor tissues compared with matching normal lung tissue (RXRalpha, 67%; RXRbeta, 55%; RXRgamma, 89%). The RXRalpha(P = 0.001) and RXRgamma(P < 0.001) median expression levels were significantly lower in the tumors. Patients whose tumors exhibited low RXRbeta expression levels had a statistically significant worse overall survival (P = 0.0005), whereas a trend toward worse survival was observed for patients with low RXRalpha expression. Multivariate analysis indicated that low RXRbeta expression is an independent predictor of worse survival in patients with NSCLC (P = 0.017).

CONCLUSION

Suppressed mRNA expression of all three RXR subtypes is a frequent event in NSCLC. Reduced RXRbeta expression might be an important biomarker for more aggressive disease in patients with NSCLC.

Quantitative adenomatous polyposis coli promoter methylation analysis in tumor tissue, serum, and plasma DNA of patients with lung cancer

The serum of cancer patients often harbors increased free DNA levels, which can potentially be used for cancer detection. Because genetic and epigenetic alterations of the adenomatous polyposis coli (APC) gene are common events in gastrointestinal tumor development, we sought to investigate the frequency and level of aberrant APC promoter methylation in primary tumors and paired preoperative serum or plasma samples of lung cancer patients by semiquantitative methylation-specific fluorogenic real-time PCR. We detected methylation of APC in 95 of 99 (96%) primary lung cancer tissues. Forty-two of 89 (47%) available serum and/or plasma samples from these cases carried detectable amounts of methylated APC promoter DNA. In contrast, no methylated APC promoter DNA was detected in serum samples from 50 healthy controls. A highly elevated APC methylation level in lung cancer tissue was the only independent factor predicting inferior survival in this cohort (P = 0.015). APC methylation analysis appears to be promising as a prognostic factor in primary lung cancer and as a noninvasive tumor marker in plasma and/or serum DNA.

ERCC1 and thymidylate synthase mRNA levels predict survival for colorectal cancer patients receiving combination oxaliplatin and fluorouracil chemotherapy

PURPOSE

To test the hypotheses of whether the relative mRNA expression of the thymidylate synthase (TS) gene and the excision cross-complementing (ERCC1) gene are associated with response to and survival of fluorouracil (5-FU)/oxaliplatin chemotherapy in metastatic colorectal cancer.

PATIENTS AND METHODS

Patients had progressive stage IV disease after unsuccessful 5-FU and irinotecan chemotherapy. All patients were evaluated for eligibility for a compassionate 5-FU/oxaliplatin protocol. cDNA was derived from paraffin-embedded tumor specimens to determine TS and ERCC1 mRNA expression relative to the internal reference gene beta-actin using fluorescence-based, real-time reverse transcriptase polymerase chain reaction.

RESULTS

The median TS gene expression level from 50 metastasized tumors was 3.4 x 10(-3) (minimum expression, 0.18 x 10(-3);maximum expression, 11.5 x 10(-3)), and the median ERCC1 gene expression level was 2.53 x 10(-3) (minimum, 0.0; maximum, 14.61 x 10(-3)). The gene expression cutoff values for chemotherapy nonresponse were 7.5 x 10(-3) for TS and 4.9 x 10(-3) for ERCC1. The median survival time for patients with TS <or= 7.5 x 10(-3) (43 of 50 patients) was 10.2 months, compared with 1.5 months for patients with TS greater than 7.5 x 10(-3) (P < .001). Patients with ERCC1 expression <or= 4.9 x 10(-3) (40 of 50 patients) had a median survival time of 10.2 months, compared with 1.9 months for patients with ERCC1 expression greater than 4.9 x 10(-3) (P < .001). A TS of 7.5 x 10(-3) segregated significantly into response, stable disease, and progression (P = .02), whereas the association between ERCC1 and response did not reach statistical significance (P = .29).

CONCLUSION

These data suggest that intratumoral ERCC1 mRNA and TS mRNA expression levels are independent predictive markers of survival for 5-FU and oxaliplatin combination chemotherapy in 5-FU-resistant metastatic colorectal cancer. Precise definition of the best TS cut point will require further analysis in a large, prospective study.

Different lengths of a polymorphic repeat sequence in the thymidylate synthase gene affect translational efficiency but not its gene expression

PURPOSE

Thymidylate synthase (TS) is a target enzyme of 5-fluorouracil. Recently, the TS gene has been shown to contain a polymorphic tandem repeat sequence. The aim of this study was to determine whether differences in the number of tandem repeats could affect gene expression or mRNA translation.

EXPERIMENTAL DESIGN

We quantified TS mRNA isolated from 130 colorectal cancer tissues by real-time reverse transcription-PCR and TS protein in 92 available samples by the fluoro-dUMP binding assay. These values were compared with TS genotypes of the samples determined by a PCR assay.

RESULTS

There was no relation between TS genotype and mRNA expression level. On the other hand, cancer tissues with the 3R/3R genotype had a significantly higher TS protein expression level than did those with the 2R/3R genotype. These results suggest that the efficiency of TS mRNA translation is responsible for the genotype-dependent difference in TS protein expression. Further analysis using TS 5'-untranslated region-luciferase reporter constructs showed that the RNA with the three-repeat sequence was translated three to four times more efficiently than that with two-repeat sequence.

CONCLUSIONS

From the results of both in vitro and in vivo study, we conclude that TS mRNA with a three-repeat sequence has greater translation efficiency than that with the two-repeat sequence. The results provide the rationale for comprehensive usage of TS genotyping with quantitation of TS mRNA or TS protein to predict the patient's response to 5-fluorouracil-based chemotherapy.

Increased c-myb mRNA expression in Barrett's esophagus and Barrett's-associated adenocarcinoma

BACKGROUND

Esophageal adenocarcinoma develops through a multistage process which is characterized histopathologically by progression from Barrett's intestinal metaplasia to Barrett's esophagus with dysplasia and ultimately to adenocarcinoma. The genetic basis of this process is increasingly well understood, but no studies have examined the role of the transcription factor c-myb in this disease.

MATERIALS AND METHODS

c-myb mRNA expression levels were measured using a quantitative reverse transcription-polymerase chain reaction (RT-PCR) method in specimens of Barrett's intestinal metaplasia (n = 16), adenocarcinoma (n = 22), matching normal squamous esophagus tissues (n = 38), and normal squamous esophagus tissues from patients without Barrett's esophagus or chronic gastroesophageal reflux disease (n = 10).

RESULTS

The median c-myb mRNA expression levels were significantly increased in Barrett's intestinal metaplasia tissues compared to normal esophagus tissues (P = 0.013) and in Barrett's-associated adenocarcinoma tissues compared to normal squamous esophagus tissues (P = 0.001). The c-myb expression levels increased progressively and significantly in histopathologically worse tissue types, with an increase from normal squamous esophagus mucosa to Barrett's intestinal metaplasia, and from Barrett's intestinal metaplasia to adenocarcinoma of the esophagus (P = 0.002). Median c-myb expression levels were also significantly higher in histologically normal squamous esophagus tissues from cancer patients compared to normal esophagus tissues from patients without cancer (P < 0.001) and a control group without evidence of Barrett's esophagus or gastroesophageal reflux disease (P = 0.003). Very high c-myb mRNA expression levels were found only in patients with cancer.

CONCLUSION

These findings suggest that upregulation of c-myb mRNA expression is an early event in the development of Barrett's esophagus and associated adenocarcinoma, that high c-myb mRNA expression levels may be a clinically useful biomarker for the detection of occult adenocarcinoma, and that a widespread cancer "field" effect is present in the esophagus of patients with Barrett's-associated adenocarcinoma.

Reversal of cytosine arabinoside (ara-C) resistance by the synergistic combination of 6-thioguanine plus ara-C plus PEG-asparaginase (TGAP) in human leukemia lines lacking or expressing p53 protein

BACKGROUND

Sequence-specific combinations of purine analogs, such as fludarabine or 6-mercaptopurine (6-MP), administered prior to cytosine arabinoside (ara-C) have been shown to abrogate ara-C resistance in human leukemia cells in vitro and in patients with relapsed acute myeloid or lymphoblastic leukemias. The two-drug combination of 6-MP plus ara-C results in greater cytotoxicity than that achieved with either ara-C or 6-MP alone. Further preclinical investigations have shown that the addition of PEG-asparaginase (PEG-ASNase) to the combination of 6-MP plus ara-C (6-MP + ara-C + PEG-ASNase) results in 15.6-fold synergism over that achieved with the two-drug regimen. This is due to increased DNA damage leading to apoptotic cell death.

PURPOSE

Since the intravenous preparation of 6-MP is no longer available and since oral 6-thioguanine (6-TG) provides higher levels of intracellular thioguanine nucleotides than an isotoxic dose of oral 6-MP, we investigated the potential drug synergism of 6-TG plus ara-C plus PEG-ASNase (TGAP) in myeloid (HL60/S, HL60/SN3, U937) and lymphoblastic (CEM/0, CEM/ ara-C/B, CEM/ara-C/I, MOLT-4) leukemia cell lines. The CEM clones, MOLT-4 and HL60/SN3 cell lines expressed functional or measurable p53 protein, while the other cell lines did not.

METHODS

The MTT and trypan blue dye exclusion assays were used to determine drug cytotoxicity. In addition, cellular apoptosis and cellular p53, p21/waf-1 and bcl-2 protein concentrations were determined by FACS analysis and ELISA assays.

RESULTS

Sequential exposure to 6-TG (24 h) plus ara-C (24 h) plus PEG-ASNase (24 h) produced 1.3- to 18.3-fold drug synergism over the two-drug combination of 6-TG plus ara-C. The molecular mechanism of synergism was due to the fact that the three-drug combination was capable of downregulating bcl-2 oncoprotein levels in these cell lines even when p53 was absent.

CONCLUSION

These studies strongly demonstrate that the TGAP regimen is highly synergistic in p53-null and p53-expressing leukemia cell lines. We conclude that this combination regimen is collaterally sensitive with ara-C and further evaluation in an investigational phase I trial in relapsed leukemia patients is warranted.

Epidermal growth factor receptor and HER2-neu mRNA expression in non-small cell lung cancer Is correlated with survival

The prognostic role of epidermal growth factor receptor (EGFR) and HER2-neu remains controversial in patients with non-small cell lung cancer (NSCLC). We studied the association between the mRNA expression of EGFR, HER2-neu, and survival in primary tumor and matching nonmalignant tissues from 83 patients with NSCLC. Analysis was performed using a quantitative real-time PCR system (Taqman). EGFR and HER2-neu mRNA expression was detectable in all (100%) specimens analyzed. Twenty-nine (34.9%) patients had high HER2-neu expression, and 28 (33.7%) patients had high EGFR expression. A high HER2-neu and EGFR coexpression was detectable in 14 (16.9%) patients. High HER2-neu expression was associated with inferior survival (P = 0.004), whereas high EGFR expression showed a trend toward inferior survival (P = 0.176). The impact of HER2-neu and EGFR coexpression on patients' survival was additive (P = 0.003). Multivariate analysis determined high HER2-neu expression (P = 0.041), and high EGFR/HER2-neu coexpression (P = 0.030) as significant and independent unfavorable prognostic factors. These findings indicate that HER2-neu and EGFR play a crucial role in the biological behavior of NSCLCs. Testing of molecular marker coexpression (EGFR and HER2-neu) improves the estimation of prognosis and appears to define low- and high-risk groups for treatment failure in curatively resected NSCLC.

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.

Thymidine kinase, thymidylate synthase, and dihydropyrimidine dehydrogenase profiles of cell lines of the National Cancer Institute's Anticancer Drug Screen

PURPOSE

To determine the expression of three targets of 5-fluorouracil (5-FU) and 5-fluoro-2'-deoxyuridine (FdUrd) in human tumor cell lines and to compare these with the 50% growth inhibition concentrations (GI(50)) from the National Cancer Institute database.

EXPERIMENTAL DESIGN

Thymidine kinase (TK) activity was assessed by conversion of [(3)H]thymidine to [(3)H]TMP. Thymidylate synthase (TS) protein expression was determined by Western analysis. TS and dihydropyrimidine dehydrogenase (DPD) mRNA expression were measured by quantitative reverse transcription-PCR.

RESULTS

The median (range) for the targets were as follows: 5-FU GI(50), 20.8 microM (0.8-536); FdUrd GI(50), 0.75 microM (0.25-237); TK, 0.93 nmol/min/mg (0.16-5.7); in arbitrary units: TS protein, 0.41 (0.05-2.95); TS mRNA, 1.05 (0.12-6.41); and DPD mRNA, 1.09 (0.00-24.4). A moderately strong correlation was noted between 5-FU and FdUrd GI(50)s (r = 0.60), whereas a weak-moderate correlation was seen between TS mRNA and protein expression (r = 0.45). Neither TS expression nor TK activity correlated with 5-FU or FdUrd GI(50)s, whereas lines with lower DPD expression tended to be more sensitive to 5-FU. Cell lines with faster doubling times and wild-type p53 were significantly more sensitive to 5-FU and FDURD:

CONCLUSIONS

The lack of correlation may in part be attributable to the influence of downstream factors such as p53, the observation that the more sensitive cell lines with faster doubling times also had higher TS levels, and the standard procedure of the screen that uses a relatively short (48-h) drug exposure.

Upregulation of ornithine decarboxylase mRNA expression in Barrett's esophagus and Barrett's-associated adenocarcinoma

The Barrett's multistage process is characterized histopathologically by progression from Barrett's intestinal metaplasia to Barrett's esophagus with dysplasia and ultimately adenocarcinoma. Understanding the cellular and molecular events in this multistage process may contribute to improved diagnosis and treatment. Ornithine decarboxylase (ODC) is the first enzyme in the biosynthesis of polyamines. Elevated ODC activity has been found to be associated with progression during Barrett's esophagus, but the regulation of ODC gene expression in the development of Barrett's-associated adenocarcinoma has not been reported. The aim of this study was to assess the prevalence and timing of ODC mRNA expression in the Barrett's metaplasia-dysplasia-adenocarcinoma sequence. ODC mRNA expression levels, relative to the stably expressed internal reference gene beta-actin, were measured using a quantitative reverse transcription-polymerase chain reaction (RT-PCR) method (ABI 7700 Sequence Detector System) in 104 specimens from 19 patients with Barrett's esophagus without carcinoma and 22 patients with Barrett's-associated adenocarcinoma. The median ODC mRNA expression levels were significantly increased in Barrett's esophagus tissues compared to matched normal tissues in patients without adenocarcinoma of the esophagus (P = 0.002; Wilcoxon test). A significant progressive increase in ODC mRNA expression was detectable through the stages of the metaplasia-dysplasia-carcinoma sequence in patients with Barrett's-associated adenocarcinoma (r = 0.719; P < or = 0.001; Spearman's rho test). These findings show that upregulation of ODC mRNA expression is an early event in the development and progression of Barrett's-associated adenocarcinoma of the esophagus, and they suggest that high ODC mRNA expression levels may be a clinically useful biomarker for the detection of occult adenocarcinoma

Retinoic acid receptor-alpha messenger RNA expression is increased and retinoic acid receptor-gamma expression is decreased in Barrett's intestinal metaplasia, dysplasia, adenocarcinoma sequence

BACKGROUND

Expression levels of the retinoic acid receptors (RAR-alpha, RAR-beta, and RAR-gamma) are significantly different in neoplastic tissues compared with non-neoplastic tissues for some tumors. This study investigated whether retinoic acid receptor messenger RNA (mRNA) expression levels are altered in Barrett's esophagus and Barrett's adenocarcinoma tissues.

METHODS

Relative mRNA expression levels of the RARs were quantified by using the ABI 7700 Sequence Detector (Taqman) system in Barrett's intestinal metaplasia (n = 15), dysplasia (n = 6), adenocarcinoma (n = 17), and matching normal esophagus tissues (n = 36).

RESULTS

RAR-alpha expression was significantly increased, and RAR-gamma expression was significantly decreased, at higher stages in the Barrett's sequence. There was almost complete loss of RAR-gamma expression (relative expression level < or = 1) in a majority (70%) of the dysplasia and adenocarcinoma tissues. There were significant differences in RAR-alpha and RAR-gamma expression in histopathologically normal tissues in patients with cancer versus patients without cancer. RAR-beta expression levels were significantly elevated in adenocarcinoma versus normal esophagus tissues. The RAR expression profile was similar for cancers arising within the esophagus and for cancers arising at the gastroesophageal junction.

CONCLUSIONS

RAR mRNA expression levels are significantly different in Barrett's tissues compared with normal esophagus tissues, and these levels are significantly different in Barrett's dysplasia and adenocarcinoma tissues compared with nondysplastic tissues. These results suggest that RAR mRNA levels may be useful biomarkers for this disease and that gastroesophageal junction adenocarcinomas are genetically similar to esophageal adenocarcinomas. These results also suggest that a cancer field is present in the esophagus in patients with cancer and that genetic alterations can precede histopathologic alterations in this disease.

[Molecular markers as basis for chemotherapy?]

Although a majority of cancer patients show no response or minimal response to any given chemotherapy, all patients are nevertheless placed on standard therapy regimens because there has been no way to identify beforehand those patients who are destined not to respond. Determining the biochemical factors relevant to drug response in each patient's tumor cells prior to treatment should allow optimal therapy to be selected for each patient on a rational basis. In this paper, we summarize studies aimed at determining whether analysis of the quantitative expression levels of genes or proteins involved in cancer drug activity in clinical specimens of tumor tissue could predict the effect of the drug on a tumor. This hypothesis has been tested mostly in 5-fluorouracil (5-FU)-based regimens in colorectal cancer. In the case of 5-FU, the quantitative expression levels of thymidylate synthase, thymidine phosphorylase, and dihydropyrimidine dehydrogenase were found to be associated with tumor response. Using all three of these markers together resulted in very effective identification of responding patients. The salient results of these studies were that, using the PCR enhanced by newly developed methodology, gene expressions can be identified and measured in pretreatment biopsies that are quantitatively associated with either response or non-response to drugs that are used in treating colorectal cancer.

Hypermethylated APC DNA in plasma and prognosis of patients with esophageal adenocarcinoma

BACKGROUND

The adenomatous polyposis coli (APC) locus on chromosome 5q21-22 shows frequent loss of heterozygosity (LOH) in esophageal carcinomas. However, the prevalence of truncating mutations in the APC gene in esophageal carcinomas is low. Because hypermethylation of promoter regions is known to affect several other tumor suppressor genes, we investigated whether the APC promoter region is hypermethylated in esophageal cancer patients and whether this abnormality could serve as a prognostic plasma biomarker.

METHODS

We assayed DNA from tumor tissue and matched plasma from esophageal cancer patients for hypermethylation of the promoter region of the APC gene. We used the maximal chi-square statistic to identify a discriminatory cutoff value for hypermethylated APC DNA levels in plasma and used bootstrap-like simulations to determine the P: value to test for the strength of this association. This cutoff value was used to generate Kaplan-Meier survival curves. All P values were based on two-sided tests.

RESULTS

Hypermethylation of the promoter region of the APC gene occurred in abnormal esophageal tissue in 48 (92%) of 52 patients with esophageal adenocarcinoma, in 16 (50%) of 32 patients with esophageal squamous cell carcinoma, and in 17 (39.5%) of 43 patients with Barrett's metaplasia but not in matching normal esophageal tissues. Hypermethylated APC DNA was observed in the plasma of 13 (25%) of 52 adenocarcinoma patients and in two (6.3%) of 32 squamous carcinoma patients. High plasma levels of methylated APC DNA were statistically significantly associated with reduced patient survival (P =.016).

CONCLUSION

The APC promoter region was hypermethylated in tumors of the majority of patients with primary esophageal adenocarcinomas. Levels of hypermethylated APC gene DNA in the plasma may be a useful biomarker of biologically aggressive disease in esophageal adenocarcinoma patients and should be evaluated as a potential biomarker in additional tumor types.

Fields of aberrant CpG island hypermethylation in Barrett's esophagus and associated adenocarcinoma

Esophageal adenocarcinoma (EAC) is thought to develop through a multistage process in which Barrett's metaplasia progresses through low- and high-grade dysplasia to invasive cancer. Transcriptional silencing of tumor suppressor genes by promoter CpG island hypermethylation has been observed in many types of human cancer. Analysis of CpG island hypermethylation in EAC has thus far been limited to the CDKN2A (p16) gene. In this study, we extend the methylation analysis of EAC to include three other genes, APC, CDH1 (E-cadherin), and ESR1 (ER, estrogen receptor alpha), in addition to CDKN2A. Molecular analysis can provide insight into the complex relationships between tissues with different histologies in Barrett's esophagus and associated adenocarcinoma. Therefore, we have mapped the spatial distribution of methylation patterns in six esophagectomy cases in detail. Hypermethylation of the four CpG islands was analyzed by the MethyLight technique in 107 biopsies derived from these six patients for a total of 428 methylation analyses. Our results show that normal esophageal squamous epithelium is unmethylated at all four CpG islands. CDH1 is unmethylated in most other tissue types as well. Hypermethylation of ESR1 is seen at high frequency in inflammatory reflux esophagitis and at all subsequent stages, whereas APC and CDKN2A hypermethylation is found in Barrett's metaplasia, dysplasia, and EAC. When it occurs, hypermethylation of APC, CDKN2A, and ESR1 is usually found in a large contiguous field, suggesting either a concerted methylation change associated with metaplasia or a clonal expansion of cells with abnormal hypermethylation.