Selective induction of tumor-associated antigens in murine pulmonary vasculature using double-targeted adenoviral vectors

Targeted therapies directed to tumor-associated antigens are being investigated for the treatment of cancer. However, there are few suitable animal models for testing the ability to target these tumor markers. Therefore, we have exploited mice transgenic for the human coxsackie and adenovirus receptor (hCAR) to establish a new model for transient expression of human tumor-associated antigens in the pulmonary vasculature. Systemic administration of Ad in hCAR mice resulted in an increase in transgene expression in the lungs compared to wild-type mice, as determined using a luciferase reporter gene. To reduce transgene expression in the liver, the predominant organ of ectopic Ad localization and transgene expression following systemic administration, we utilized the endothelial-specific flt-1 promoter, which resulted in a further increased lung-to-liver ratio of luciferase expression. Administration of an adenoviral vector encoding the tumor-associated antigen carcinoembryonic antigen (CEA) under transcriptional control of the flt-1 promoter resulted in selective expression of this antigen in the pulmonary vasculature of hCAR mice. Feasibility of targeting to expressed CEA was subsequently demonstrated using adenoviral vectors preincubated with a bifunctional adapter molecule recognizing this tumor-associated antigen, thus demonstrating utility of this transient transgenic animal model.

Genetic segregation of spontaneous erosive arthritis and generalized autoimmune disease in the BXD2 recombinant inbred strain of mice

The BXD2 strain of mice is one of approximately 80 BXD recombinant inbred (RI) mouse strains derived from an intercross between C57BL/6J (B6) and DBA/2J (D2) strains. We have discovered that adult BXD2 mice spontaneously develop generalized autoimmune disease, including glomerulonephritis (GN), increased serum titres of rheumatoid factor (RF) and anti-DNA antibody, and a spontaneous erosive arthritis characterized by mononuclear cell infiltration, synovial hyperplasia, and bone and cartilage erosion. The features of lupus and arthritis developed by the BXD2 mice segregate in F2 mice generated by crossing BXD2 mice with the parental B6 and D2 strains. Genetic linkage analysis of the serum levels of anti-DNA and RF by using the BXD RI strains shows that the serum titers of anti-DNA and RF were influenced by a genetic locus on mouse chromosome (Chr) 2 near the marker D2Mit412 (78 cm, 163 Mb) and on Chr 4 near D4Mit146 (53.6 cm, 109 Mb), respectively. Both loci are close to the B-cell hyperactivity, lupus or GN susceptibility loci that have been identified previously. The results of our study suggest that the BXD2 strain of mice is a novel model for complex autoimmune disease that will be useful in identifying the mechanisms critical for the immunopathogenesis and genetic segregation of lupus and erosive arthritis.

Intratumor heterogeneity of biomarker expression in breast carcinomas

Small biopsy samples are used increasingly to assess the biomarker expression for prognostic information and for monitoring therapeutic responses prior to and during neoadjuvant therapy. The issue of intratumor heterogeneity of expression of biomarkers, however, has raised questions about the validity of the assessment of biomarker expression based on limited tissue samples. We examined immunohistochemically the expression of HER-2neu (p185erbB-2), epidermal growth factor receptor (EGFR), Bcl-2, p53, and proliferating cell nuclear antigen (PCNA) in 30 breast carcinomas using archived, paraffin embedded tissue and determined the extent of intratumor heterogeneity. Each section was divided into four randomly oriented discrete regions, each containing a portion of the infiltrating carcinoma. For each tumor, the entire lesion and four regions were analyzed for the expression of these markers. Scores of both membrane and cytoplasmic staining of HER-2neu and EGFR, scores of cytoplasmic staining of Bcl-2, and scores of nuclear staining of both p53 and PCNA were recorded. The intensity of staining and the proportion of immunostained cells were determined. A semiquantitative immunoscore was calculated by determining the sum of the products of the intensity and corresponding proportion of stained tumor cells. We analyzed both invasive (IDC) and in situ (DCIS) carcinomas. The Wilcoxon signed-rank test was used for paired comparisons between overall and regional immunoscores and between overall and regional percentages of stained cells. Spearman's correlation coefficients were used to assess the level of agreement of overall biomarker expression with each of the regions. Generalized linear models were used to assess overall and pair-wise differences in the absolute values of percent changes between overall and regional expression of biomarkers. For IDCs, there were no statistically significant differences in the expression of the biomarkers in terms of either the percentage of cells staining or the immunoscores when comparing the entire tumor with each region except for the lower EGFR expression of arbitrarily selected region 1 and lower p53 expression of region 1 compared to that of the entire tumor section. For DCIS, there were no statistically significant differences in the expression of the biomarkers between the entire tumor and each region except in PCNA of region 2 compared to that of entire tumor section. Positive correlation of immunoscores was observed between the entire tumor and each region as well as across all four regions for IDC. Similar observations were noted with DCIS except for HER-2neu and PCNA. No statistically significant differences were observed in the absolute values of percent changes of biomarker expression between overall and the four regions for both DCIS and IDC. Therefore, no significant intratumor heterogeneity in the expression of HER-2neu, Bcl-2, and PCNA was observed in IDC. Minor regional variations were observed for EGFR and p53 in IDC. Similarly, no significant regional variation in the expression of markers was observed in DCIS except for PCNA.

Establishing a tumour bank: banking, informatics and ethics

The six divisions of the Cooperative Human Tissue Network in the USA bank and distribute tens of thousands of tissue specimens to researchers annually. Major operational concerns include: maintaining tissue integrity, managing informatics, and protecting patient confidentiality. Increasing molecular genetics testing is also resulting in an increased demand for high-quality nucleic acids.

Cellular mechanism of thymic involution

Involution of the thymus and alterations in the development of thymocytes are the most prominent features of age-related immune senescence. We have carried out a comparative analysis of thymocyte and stroma in rapid thymic involution DBA/2 (D2) strain of mice compared with slow involution C57BL/6 (B6) strain of mice. Analysis of mice at 15 months of age suggested an age-related decrease in the thymocyte cell count, a block in the development of T cells and cortical involution in D2 mice compared with 3-month-old mice. TUNEL (terminal-deoxynucleotidyl-transferase-mediated dUTP-digoxigenin nick end labelling) staining and fluorescence-activated cell sorter (FACS) analysis showed that there was a significant increase in apoptotic cells in the cortex region of thymus in 15-month-old D2 mice compared with the same aged B6 mice. The thymocyte proliferation rate, as assessed by bromodeoxyuridine (BrdU) staining and [3H]-thymidine incorporation assay, was lower in 3-month-old D2 mice compared with the same age B6 mice. Immunohistochemical staining showed that the arrangement of MTS (mouse thymus stromal)-10+ epithelial cells and MTS-16+ connective tissue staining pattern had become disorganized in 15-month-old D2 mice but remained intact in B6 mice of the same age. These results suggest that, in D2 mice, both the thymocytes and stromal cells exhibit age-related defects, and that the genetic background of mice plays an important role in determining age-related alterations in thymic involution.

The use of dimethylsulfoxide as a vehicle in cell culture experiments using ovarian carcinoma cell lines

Dimethylsulfoxide (DMSO) is a well-known solvent that is commonly used in the laboratory. We selected DMSO as the vehicle for an experiment designed to determine if several nonsteroidal anti-inflammatory agents inhibit the growth of Caov-3, OVCAR-3, and SK-OV-3 ovarian carcinoma cell lines. Using the tetrazolium conversion assay, however, we observed some variability in the number of cells present in each ovarian carcinoma cell line with varying concentrations of DMSO (10(-6)-10(-2) M) compared to medium alone. Similarly, when Caov-3, OVCAR-3, and SK-OV-3 cells were treated with 10(-4) M DMSO plus medium (Dulbecco's Modified Eagle Medium with 10% fetal bovine serum) and plated on coverslips, the total number of cells present in 60 random fields increased significantly (P < 0.0001) for each ovarian carcinoma cell line treated with DMSO compared to medium alone. Ethanol did not demonstrate such prominent effects on cellular growth. Our observations are important to consider when selecting an appropriate solvent, especially for growth inhibition studies using Caov-3, OVCAR-3, and SK-OV-3 cell lines.

The response of extracellular signal-regulated kinase (ERK) to androgen-induced proliferation in the androgen-sensitive prostate cancer cell line, LNCaP

The mechanisms by which androgens stimulate proliferation of prostate cancer cells are poorly understood. It has been proposed that androgen stimulation may induce the mitogen-activated protein (MAP) kinase system in prostate cancer cells and lead to cellular proliferation. We attempted to evaluate the role of the extracellular signal-regulated kinase (ERK) pathway in the stimulation by androgens of prostate cancer cell proliferation. Androgen-sensitive prostate cancer cell line (LNCaP) cells plated on sterile glass coverslips were treated with 10(-8) M dihydrotestosterone (DHT) or epidermal growth factor (EGF) (10 ng/ml) for periods ranging from 1 min to 96 h. The proliferative index of the cells, evaluated by immunoperoxidase staining of cells with an antibody to Ki-67, was increased at least two-fold at all time points from 5 min to 48 h following exposure to either DHT or EGF. Immunohistochemical evaluation of ERK1/2 and pERK (activated ERK) demonstrated high levels of ERK1/2 in untreated LNCaP cells, while pERK was expressed at much lower levels. Following treatment with DHT, no change in staining intensity for either ERK1/2 or pERK was observed, while treatment with EGF resulted in no change in ERK1/2, but significantly increased cytoplasmic staining for pERK at all time points beyond 2 min. These results were confirmed by Western blot analysis of ERK1/2 and pERK expression in these cell lines following treatment with DHT or EGF. Our findings suggest that the proliferative response of prostate cancer cells to androgens, unlike the proliferative response to EGF, is not mediated by the activation of ERK1/2, and that currently undefined pathways other than those involving ERK1/2 are involved.

Race- and age-dependent alterations in global methylation of DNA in squamous cell carcinoma of the lung (United States)

OBJECTIVE

The current study investigated the race- and age-dependent alterations in global DNA methylation on the development and progression of squamous cell carcinomas (SCCs) of the lung.

METHODS

Methylation status was evaluated in SCC and in the associated uninvolved bronchial mucosa (UBM) and epithelial hyperplasia (EH) of 53 Whites and 23 African Americans by using an antibody specific for 5-methylcytosine (5-mc). A low 5-mc score indicates global hypomethylation of DNA.

RESULTS

5-mc scores of SCC were significantly lower compared to 5-mc scores of UBM and EH in Whites (p < 0.05). In African Americans, 5-mc scores of SCCs were not significantly different from 5-mc scores of UBM and EH, suggesting an involvement of methylation in the development of SCCs in Whites, but not in African Americans. 5-mc scores were lower in younger subjects compared to older subjects in Whites. Since cancers in younger subjects tend to be more aggressive than cancers in older subjects, these observations may suggest that hypomethylation may have contributed to aggressiveness cancers of younger Whites. Hypomethylation of SCCs in White men was associated with shorter survival from the disease.

CONCLUSIONS

These preliminary results suggest that the methylation status of DNA may affect the development, aggressiveness, and prognosis of SCCs in Whites.

Altered subcellular localization of suppressin, a novel inhibitor of cell-cycle entry, is an independent prognostic factor in colorectal adenocarcinomas

PURPOSE

Suppressin (SPN), a novel inhibitor of the entry into the cell cycle, has properties of a tumor suppressor gene; however, its role in the development and progression of a human malignancy is not studied. Therefore, we evaluated the status of spn and its prognostic value in human colorectal adenocarcinoma (CRC).

EXPERIMENTAL DESIGN

Inhibition of cell proliferation by exogenous/extracellular SPN was assessed by [(3)H]thymidine incorporation. The genetic status of spn in two colon cancer cell lines (LS180 and WiDr) and in a human CRC was determined using direct cDNA sequencing techniques. Phenotypic expression of SPN was evaluated in 105 CRC archival tissues using immunohistochemical methods. Univariate Kaplan-Meier and multivariate Cox proportional hazards models were used to determine the prognostic significance of SPN expression.

RESULTS

Exogenous SPN inhibited the proliferation of the LS180 cell line, which also has a mutation in one allele of the spn gene. The spn gene was also mutated in the primary CRC. Expression of SPN was primarily cytoplasmic in nonmucinous CRCs and nuclear in mucinous CRCs. However, the evaluation of 85 nonmucinous CRCs demonstrated that nuclear localization of SPN, nuclear accumulation of p53, and nodal status were independent prognostic indicators with hazard ratios of 2.34, 2.33, and 3.04, respectively. Nuclear localization of SPN plus nuclear accumulation of p53 formed a stronger prognostic indicator (hazard ratios = 5.45) than local nodal status.

CONCLUSIONS

This is the first report of genetic alterations in the spn gene in a human malignancy and suggests that genetic alterations in spn and the resulting immunohistochemical phenotypes based on SPN subcellular localization in CRCs may be useful in determining prognosis of patients with subtypes of CRC.

Combined transductional and transcriptional targeting improves the specificity of transgene expression in vivo

The promise of gene therapy for health care will not be realized until gene delivery systems are capable of achieving efficient, cell-specific gene delivery in vivo. Here we describe an adenoviral system for achieving cell-specific transgene expression in pulmonary endothelium. The combination of transductional targeting to a pulmonary endothelial marker (angiotensin-converting enzyme, ACE) and an endothelial-specific promoter (for vascular endothelial growth factor receptor type 1, flt-1) resulted in a synergistic, 300,000-fold improvement in the selectivity of transgene expression for lung versus the usual site of vector sequestration, the liver. This combined approach should be useful for the design of other gene delivery systems.

Altered global methylation of DNA: an epigenetic difference in susceptibility for lung cancer is associated with its progression

Alterations in global DNA methylation have been observed in many cancers, but whether such alterations represent an epigenetic difference in susceptibility for the disease is unknown. The status of global DNA methylation also has not been reported in intact or specific types of cells involved in the carcinogenic process. To address these issues in lung carcinogenesis, we evaluated the status of global DNA methylation by using a monoclonal antibody specific for 5-methylcytosine (5-mc) in randomly selected lung specimens of 60 cigarette smokers who developed squamous cell carcinoma (SCC) and 30 cigarette smokers who did not. 5-mc immunostaining scores of DNA of SCC (0.61 +/- 0.42) and associated hyperplastic lesions (0.82 +/- 0.27) was significantly lower than those of DNA of histologically normal bronchial epithelial cells (0.99 +/- 0.52) and hyperplastic lesions (1.2 +/- 0.22) of noncancer specimens. The ratio of 5-mc scores between SCC and matched uninvolved bronchial epithelial cells was significantly associated with advanced stage and size of the tumor. The results suggest that alteration in global DNA methylation is an important epigenetic difference in susceptibility for the development of lung cancer. The reduced global DNA methylation in SCC compared with epithelial hyperplasia and its association with tumor size and disease stage is suggestive of its involvement in the progression of SCC. The results also indicate that normal methylation of DNA in epithelial hyperplastic lesions may prevent the transformation of these lesions to invasive cancer. If these results are confirmed, the status of DNA methylation in early lesions such as epithelial hyperplasia could be used to identify smokers who are at risk for the development of SCC.

Intraperitoneal radioimmunochemotherapy of ovarian cancer: a phase I study

A phase I trial was designed to examine the feasibility of combining interferon and Taxol with intraperitoneal radioimmunotherapy (177Lu-CC49). Patients with recurrent or persistent ovarian cancer confined to the abdominal cavity after first line therapy, Karnofsky performance status > 60, adequate liver, renal and hematologic function, and tumor that reacted with CC49 antibody were enrolled. Human recombinant alpha interferon (IFN) was administered as 4 subcutaneous injections of 3 x 10(6) U on alternate days beginning 5 days before RIT to increase the expression of the tumor-associated antigen, TAG-72. The addition of IFN increased hematologic toxicity such that the maximum tolerated dose (MTD) of the combination was 40 mCi/m2 compared to 177Lu-CC49 alone (45 mCi/m2). Taxol, which has radiosensitizing effects as well as antitumor activity against ovarian cancer, was given intraperitoneally (i.p.) 48 hrs before RIT. It was initiated at 25 mg/m2 and escalated at 25 mg/m2 increments to 100 mg/m2. Subsequent groups of patients were treated with IFN + 100 mg/m2 Taxol + escalating doses of 177Lu-CC49. Three or more patients were treated in each dose group and 34 patients were treated with the 3-agent combination. Therapy was well tolerated with the expected reversible hematologic toxicity. The MTD for 177Lu-CC49 was 40 mCi/m2 when given with IFN + 100 mg/m2 Taxol. Interferon increased the effective whole body half-time of radioactivity and the whole body radiation dose. Taxol did not have a significant effect on pharmacokinetic or dosimetry parameters. Four of 17 patients with CT measurable disease had a partial response (PR) and 4 of 27 patients with non-measurable disease have progression-free intervals of 18+, 21+, 21+, and 37+ months. The combination of intraperitoneal Taxol chemotherapy (100 mg/m2) with RIT using 177Lu-CC49 and interferon was well tolerated, with bone marrow suppression as the dose-limiting toxicity.

Molecular differences in mucoepidermoid carcinoma and adenoid cystic carcinoma of the major salivary glands

OBJECTIVE/HYPOTHESIS

Mucoepidermoid carcinoma (MEC) and adenoid cystic carcinoma (ACC), the most common malignancies of the major salivary glands, are clinically and pathologically different. To determine whether MEC and ACC have different molecular characteristics, we examined the expression of erbB-2, erbB-3, epidermal growth factor receptor (EGFR), and transforming growth factor-alpha (TGF-alpha), important molecular features in other malignancies.

STUDY DESIGN/METHODS

Archival tissue sections of 22 MEC and 6 ACC tumors of the major salivary glands were evaluated immunohistochemically for expression of erbB-2, erbB-3, EGRF, and TGF-alpha. A differential immunostaining score, reflecting the difference in immunostaining between carcinoma and uninvolved salivary gland tissue, was calculated for cytoplasmic and membranous staining.

RESULTS

Positive immunostaining for all biomarkers was observed in the cytoplasm and membrane of both tumors. However, expression was higher in MEC than in ACC tumors and was statistically significant for cytoplasmic EGFR (P =.009), TGF-alpha (P =.041), and membranous EGFR (P =.004). A significantly higher percentage of MEC cells also demonstrated positive immunostaining for cytoplasmic erbB-3 (P =.022), EGFR (P =.005), membranous erbB-3 (P =.022), and EGFR (P =.013). The differential immunostaining score was significantly higher for MEC compared with uninvolved alveolar tissue and the membranes of uninvolved ductal tissue. There were no statistically positive differential immunostaining scores for ACC.

CONCLUSIONS

There is a clear difference in the molecular phenotypes of MEC and ACC. The lack of statistically significant expression in ACC, when compared with similar uninvolved salivary gland tissue, suggests minimal involvement for these molecular structures in the pathogenesis of ACC. Conversely, erbB-2, erbB-3, EGFR, and TGF-alpha may have a role in the development and progression of MEC. These results have therapeutic implications for MEC of the major salivary glands.

Avoiding biohazards in medical, veterinary and research laboratories

Personnel in medical, veterinary or research laboratories may be exposed to a wide variety of pathogens that range from deadly to debilitating. For some of these pathogens, no treatment is available, and in other cases the treatment does not fully control the disease. It is important that personnel in laboratories that process human or microbiological specimens follow universal precautions when handling tissues, cells, or microbiological specimens owing to the increasing numbers of individuals infected with hepatitis C and HIV in the US and the possibility that an individual may be asymptomatic when a specimen is obtained. Similar precautions must be followed in laboratories that use animal tissues owing to the possibility of exposure to agents that are pathogenic in humans. Personnel with conditions associated with immunosuppression should evaluate carefully whether or not specific laboratory environments put them at increased risk of disease. We offer here some general approaches to identifying biohazards and to minimizing the potential risk of exposure. The issues discussed can be used to develop a general safety program as required by regulatory or accrediting agencies, including the Occupational Safety and Health Administration.

Genetic dissection of age-related changes of immune function in mice

Understanding of the genetic basis of normal and abnormal development of the immune response is an enormous undertaking. The immune response, at the most minimal level, involves interactions of antigen presenting cells (APCs), T and B cells. Each of these cells produce cell surface and soluble factors (cytokines) that affect both autocrine and paracrine functions. A second level of complexity needs to consider the development of the macrophage/monocyte lineage as well as the production of the common lymphoid precursor which undergoes distinct maturation steps in the thymus and periphery to form mature T cells as well as in BM (BM) and lymphoid organs to form mature B cells. A third level of complexity involves the immune response to infectious agents including viruses and also the response to tumour antigens. In addition, there are imbalances that predispose to decreased responses (immunodeficiencies) or increased responses (autoimmunity). A fourth level of complexity involves attempts to understand the differences in the immune response that occurs at a very young age, in adults, and at a very old age. This review will focus on the use of C57BL/6 J X DBA/2 J (BXD) recombinant inbred (RI) strains of mice to map genetic loci associated with the production of lymphoid precursors in the BM, development of T cells in the thymus, and T-cell responses to stimulation in the peripheral lymphoid organs in adult and in aged mice. Strategies to improve the power and precision in which complex traits such as the age-related immune response can be mapped is limited with the current set of 35 strains of BXD mice. Strategies to increase these strains by generating recombinant intercross (RIX) strains of mice are being developed to enable this large set of lines to detect quantitative trait loci (QTLs) with a much higher consistency and statistical power. More importantly, the resolution with which these QTLs can be mapped would be greatly improved and, in many cases, adequate to carry out direct identification of candidate genes. It is likely that, given the complexity of the immune system development, the number of cells involved in an immune response, and especially the changes in the immune system with ageing, mapping hundreds of genes will be required to fully understand age-related changes in the immune response. This review outlines ongoing and future strategies that will enable the mapping and identification of these genes.

Immunohistochemical expression of molecular markers in an avian model: a potential model for preclinical evaluation of agents for ovarian cancer chemoprevention

OBJECTIVE

A significant obstacle confronting the evaluation of potential chemopreventive compounds in ovarian carcinoma is the absence of an animal model of spontaneous ovarian carcinogenesis. A potential model of adenocarcinoma has been described in the laying hen (Gallus domesticus). The purpose of this study was to evaluate the immunohistochemical expression of available antibodies that have been utilized in chemoprevention studies in this potential model of epithelial carcinoma.

METHODS

Two hundred 2-year-old hens were sacrificed at Auburn University in accordance with IUACUC guidelines. Of these hens, 8 animals were thought grossly to have ovarian carcinoma and ascites. The tumors from these 8 hens were fixed in neutral-buffered formalin and processed to paraffin blocks. Hematoxylin and eosin stains were used to document the histologic presence of adenocarcinoma. Immunohistochemical evaluation for expression of antigen was performed using the following antibodies: CA125, CEA, cytokeratin, EGFR, erbB-2, Ki-67, Lewis Y, p27, PCNA, Tag 72, TGF-alpha, Muc 1, and Muc 2.

RESULTS

Upon microscopic examination by a pathologist eight specimens were documented as adenocarcinomas. Several antibodies to antigens that are frequently expressed in human ovarian cancer were cross-reactive in the laying hen. Of these, cytokeratin AE1/AE3, pan cytokeratin, EGFR, Lewis Y, CEA, Tag 72, and erbB-2 stained the chicken carcinomas. EGFR and p185erbB-2 stained diffusely, and cytokeratin AE1/AE3, pan cytokeratin, Lewis Y, CEA, and Tag 72 were focally positive in the tumor. The aforementioned antibodies which have been useful as surrogate endpoints in chemoprevention trials and which also stained the chicken carcinomas included PCNA, p27, and TGF-alpha Antibodies that were not cross-reactive include CA 125, Ki-67, Muc 1, and Muc 2.

CONCLUSION

The data presented in this pilot study support the potential utility of an avian model of spontaneously arising adenocarcinoma in which to study chemopreventive agents. More importantly, the influence of chemoprevention protocols on the expression of relevant antigens can be determined using available antibodies that are cross-reactive in this model. Thus, changes in the phenotypic expression of surrogate endpoint biomarkers as identified by cross-reactive antibodies can aid in the development of chemoprevention trials for human ovarian cancer.

Localized folate and vitamin B-12 deficiency in squamous cell lung cancer is associated with global DNA hypomethylation

We measured the concentrations of folate and vitamin B-12 in paired tissue samples of squamous cell cancer (SCC) and adjacent grossly normal-appearing uninvolved bronchial mucosa (from which SCC developed and also "at risk" of developing SCC) of the lung in 12 subjects to determine the involvement of these vitamins in 1) lung carcinogenesis and 2) global DNA methylation. The folate concentrations were significantly lower in SCCs than in uninvolved tissues (p = 0.03). The vitamin B-12 concentrations were also significantly lower in SCCs than in uninvolved tissues (p = 0.02). The radiolabeled methyl incorporation (inversely related to the degree of in vivo DNA methylation) was significantly higher in SCCs than in uninvolved tissues (p < 0.0001). The correlation between folate and radiolabeled methyl incorporation was inverse and statistically significant in SCCs (p = 0.03). The correlation between vitamin B-12 and radiolabeled methyl incorporation also was inverse and statistically significant in SCCs (p = 0.009). The relationship between tissue vitamin B-12 and DNA methylation was minimal in uninvolved tissues. The relationship between folate and DNA methylation, however, was inverse in uninvolved tissues. In the multiple regression models that included both vitamins, only folate was inversely associated with radiolabeled methyl incorporation in uninvolved and cancerous tissues. These results suggested that folate might be the limiting vitamin for proper DNA methylation in SCC as well as in tissues at risk of developing SCC. Several possible mechanisms of folate deficiency, including inactivation of the vitamin by exposure to carcinogens of cigarette smoke and underexpression or absence of folate receptor in SCCs and associated premalignant lesions, are discussed in light of these findings.

Molecular biomarkers for breast cancer prognosis: coexpression of c-erbB-2 and p53

OBJECTIVE

To assess the prognostic significance of molecular biomarkers, particularly c-erbB-2 and p53, through study of prospective clinical data and archival breast cancer tissues for women accrued to the Alabama Breast Cancer Project.

SUMMARY BACKGROUND DATA

Defining molecular abnormalities in breast cancer is an important strategy for early detection, assessment of prognosis, and treatment selection. Evidence is strong that selective biomarkers, including c-erbB-2 and p53, have prognostic significance in breast cancer. Few studies have analyzed the prognostic significance of coexpression of biomarkers.

METHODS

Study patients were those accrued to the Alabama Breast Cancer Project (1975-1978) who had archival breast cancer tissues available for analysis. Criteria for entrance into the Alabama Breast Cancer Project were T1-3 breast cancer with M0 status. Age, nodal status, and histologic grade were also documented. Patients were randomized to radical versus modified radical mastectomy, and node-positive patients were also randomized to adjuvant chemotherapy (cyclophosphamide, methotrexate, and 5-fluorouracil [CMF]) versus melphalan. Archival breast cancer tissues were studied for c-erbB-2, TGF-alpha, p53, cathepsin D, bcl-2, and estrogen and progesterone receptor expression using immunohistochemistry. Survival curves were developed using the Kaplan-Meier method. Univariate analysis was performed using the log-rank test, multivariate analysis using a rank regression model.

RESULTS

Three hundred eleven patients were accrued to the Alabama Breast Cancer Project, and paraffin-embedded breast cancer tissues for 90 patients were available for immunohistochemical analysis of molecular biomarkers. Univariate analysis showed nodal status, c-erbB-2 expression, and p53 expression to have prognostic significance. Coexpression of c-erbB-2 and p53 was also found to have prognostic significance by the log-rank test. Multivariate analysis showed T stage, nodal status, c-erbB-2 expression, and p53 expression to have independent prognostic significance.

CONCLUSIONS

These data suggest that c-erbB-2 and p53 expression in breast cancer have prognostic significance. After median follow-up of 16 years, coexpression of c-erbB-2 and p53 may have more prognostic significance than traditional prognostic factors such as T stage and nodal status. Prospective study of large numbers of patients with breast cancer is encouraged to validate these findings.

Bayesian monitoring of a phase 2 chemoprevention trial in high-risk cohorts for prostate cancer

The objective of phase 2 cancer chemoprevention trials is to evaluate whether a chemopreventive agent will cause significant modulation of intermediate endpoint biomarkers (IEB) in patients at high risk for the disease. A phase 2 chemoprevention trial of 4-hydroxyphenyl retinamide (4-HPR) versus placebo was conducted in men with a histologic diagnosis of early prostate cancer and scheduled to have radical prostatectomy. A Bayesian monitoring method was used to sequentially monitor this trial for evidence of biological activity or ineffectiveness based on a single IEB variable. Different prior distributions were used and posterior distributions were obtained to calculate the probability that treatment differences are greater than or less than a predetermined clinically significant effect. The interim analysis of transforming growth factor-alpha expression indicated a high probability of insufficient biological activity of 4-HPR on this IEB. This study demonstrates the potential utility of Bayesian methods in the decision-making process in the conduct of phase 2 chemoprevention trials.