Characterization of the cyclooxygenase-2 promoter in an adenoviral vector and its application for the mitigation of toxicity in suicide gene therapy of gastrointestinal cancers

The application of adenoviral molecular chemotherapy for systemic malignant disease using herpes simplex virus thymidine kinase has been limited by ectopic transgene expression in the liver due to the vector hepatotropism. The aim of this study was to mitigate this hepatotoxicity using the promoter of cyclooxygenase-2, inactive in liver but active in many gastrointestinal cancers. To analyze the specificity of transgene expression driven by cyclooxygenase-2 (cox-2) promoters, promoters of two different lengths were incorporated into adenoviral vectors to drive luciferase expression. The specific cytocidal effect and in vivo toxicity were analyzed with thymidine kinase expression vectors. The specificity of the cox-2 promoter was well preserved in the adenoviral vector. In vivo, the cox-2 promoter (-1432/+59) showed very little activity in the liver but attained high activity, comparable to that of the cytomegalovirus promoter, in cyclooxygenase-2-positive subcutaneous tumors. The cox-2 promoter-driven thymidine kinase-expressing vectors showed a cytocidal effect specifically in cyclooxygenase-2-positive cells. When mice were treated with the thymidine kinase-expressing vector and ganciclovir, the cox-2 promoter successfully mitigated the fatal hepatotoxicity, which was observed with the cytomegalovirus promoter-driven vector. The cox-2 promoter successfully mitigated the adverse effects of adenoviral suicide gene therapy by minimizing transgene expression in the liver.

Effects of acute and chronic body weight gain reductions in the evaluation of agents for efficacy in mammary cancer prevention

Studies were performed to determine the effects of moderate decreases in body weight gain on mammary carcinogenesis. The levels of depressions in weight gain were those often observed in the evaluation of chemopreventive agents. In the first experiment, the effects of acute and chronic reductions of body weight gain when started after carcinogen treatment were examined in young rats (MNU at 50 days of age). Significant decreases (36%) in mammary cancers occurred in groups of rats that underwent a 12% acute reduction in body weight gain as compared with ad libitum controls. In contrast, chronic weight reductions of up to 12% had minimal effects on cancer multiplicities, while a 15% chronic reduction significantly decreased cancer numbers (26%). A second experiment evaluated the efficacy of toremifene (7.0 mg/kg diet), an estrogen/anti-estrogen, and the effect of toremifene-matched body weight gain reduction that occurred during the study. Toremifene caused a chronic reduction in body weight that resulted in a 10% decrease in final body weight at the end of the study. While toremifene-treated rats exhibited a 67% decrease in the number of mammary cancers, the <matched body weight reduction> rats which similarly exhibited a 10% decrease in final body weight showed only a 14% decrease in cancer number. Thus, the weight effects observed with toremifene, similar estrogens/anti-estrogens, and other classes of chemopreventive compounds (where chronic body weight reductions are 10% or less) imply that the body weight reduction has a limited effect on overall chemopreventive activity. A third study examined the effect of chronic body weight gain reduction on mammary cancers induced in older rats (MNU given at 100 days of age). This model more closely resembles the status of the breast tissue of mature women currently enrolled in clinical trials of chemopreventive agents. Under these conditions chronic reductions in body weight up to 15% had minimal effects on mammary carcinogenesis. These data further demonstrated that acute body weight reductions in young rats at the time of carcinogen treatment can be a concern in interpretation of the chemopreventive activity of an agent, but that moderate chronic depressions of body weight gain probably do not play a significant role.

Effects of time and temperature during attachment of sections to microscope slides on immunohistochemical detection of antigens

To study the effects of time and temperature on attachment of tissue sections to microscope slides, we examined the intensity of immunohistochemical staining of selected antigens in nine different neoplastic and normal tissues after attaching sections at different times and temperatures. Typically, both the temperature and time are minimized when tissue sections attached to slides; however, suboptimal times and temperatures during attachment may result in either loss of tissue due to poor attachment or the necessity for inconvenient staining regimens. Using standard immunohistochemical techniques, 5 microm tissue sections were attached at 58 degrees C for 1, 4 and 24 hr. In a separate study, 5 microm tissue sections were attached for 16 hr at 58, 68 and 80 degrees C. The intensity of staining decreased slightly when the tissue sections were heated at 80 degrees C for 16 hr, but there was little or no decrease when tissues were heated at 68 degrees C or lower for 16 hr, or at 58 degrees C for up to 24 hr.

Fatty acid synthase: an early molecular marker of progression of prostatic adenocarcinoma to androgen independence

PURPOSE

Changes in fatty acid synthase levels were investigated in the CWR22 xenograft model of prostatic adenocarcinoma after castration and during progression to androgen independence.

MATERIALS AND METHODS

Male nude mice with CWR22 tumors were castrated and sacrificed 3, 7, 21, 28 or 42 days after castration. Some mice received testosterone replenishment 21 days after castration and were sacrificed 7 days later. In addition, other castrates were maintained for 7 to 10 months to allow tumors to relapse to androgen independence. Fatty acid synthase was measured by immunohistochemical study and Western blot analysis.

RESULTS

Fatty acid synthase decreased rapidly after castration and after 28 to 42 days it was 5% to 10% of the level in tumors of intact controls. Temporal changes in fatty acid synthase after castration were associated with decreased proliferative potential and increased levels of the cyclin dependent kinase inhibitor p27Kip-1. Testosterone treatment of castrates at 21 to 28 days after castration increased fatty acid synthase expression to the level in tumors of intact controls. Tumors of long-term castrates with post-castration androgen independent growth had increased fatty acid synthase, as did small focal areas of androgen independent proliferation in tumors that had not increased in size by 7 to 10 months. In relapsed CWR22 tumors and in focal areas of androgen independent proliferation in nonrelapsed CWR22 tumors increased fatty acid synthase was associated spatially with increased proliferation and decreased p27Kip-1.

CONCLUSIONS

Fatty acid synthase in CWR22 tumors depends initially on testosterone and it is associated with androgen mediated proliferation. Furthermore, increased fatty acid synthase levels associated with androgen independent proliferation may represent an early event in the development of the androgen independent phenotype.

Molecular characterization of colorectal neoplasia in translational research

OBJECTIVE

To present recent advances in the use of molecular markers in diagnosis, in prognosis, in early detection, in novel therapies, and in understanding the molecular pathogenesis of colorectal neoplasia.

DATA AND LITERATURE SOURCES

A review of studies of molecular markers in colorectal neoplasia, published in English and available on MEDLINE and BioMednet, indicates that molecular markers are being increasingly studied to predict clinical outcomes in patients with colorectal adenocarcinoma (CRC). We have used this resource, together with our published and unpublished observations at the University of Alabama at Birmingham, to provide an overview of translational research related to molecular markers in colorectal neoplasia.

CONCLUSIONS

Currently, the prognosis of patients with CRC is predicted primarily on the basis of clinicopathologic staging; however, pathologists and oncology surgeons have recently begun to investigate the use of molecular markers to diagnose and/or understand the progression of CRC. In recent years, much has been learned about the molecular events responsible for the development of CRC. Also, several studies have reported the implication of some molecular markers in metastasis and tumor aggression and their usefulness in predicting clinical outcome. In this article, we discuss the use of specific molecular markers, including tumor-associated glycoprotein 72 (TAG-72), carcinoembryonic antigen (CEA), and oncofetal tumor antigens (Lewis X and Y) in diagnosis and as targets for novel therapies, as well as the phenotypic expression of bcl-2, mucin antigens (MUC1 and MUC2), and nuclear accumulation of p53 in predicting the clinical outcome of patients with CRC. We also review the ways in which molecular markers may aid the early detection of colorectal neoplasia and promote our understanding of the earliest changes in colorectal neoplasia.

The effect of isolated soy protein on plasma biomarkers in elderly men with elevated serum prostate specific antigen

PURPOSE

We performed a randomized double-blind crossover pilot study in elderly men with elevated prostate specific antigen (PSA) on the effects of the daily consumption of 2 soy beverages, each containing 20 gm. of isolated soy protein, on the isoflavone concentration in blood and urine, and on the 3 serum biomarkers cholesterol, PSA and the soluble p105 component of the p185erbB-2 proto-oncogene.

MATERIALS AND METHODS

A total of 34 men supplemented their diet by consuming 1 of 2 soy protein beverages assigned randomly twice daily for a 6-week period. In a second 6-week period they consumed the other soy protein beverage. The beverage ISP+ provided 42 mg. of genistein and 27 mg. of daidzein daily, whereas the other beverage, ISP-, provided only 2.1 and 1.3 mg. of these isoflavones daily, respectively. Blood and 24-hour urine samples were obtained before the study, at 2-week intervals during the study and 2 weeks after study completion.

RESULTS

ISP+ and to a lesser extent ISP- substantially increased the serum concentration and urinary output of the isoflavones and their metabolites. Serum cholesterol was significantly decreased by ISP+ irrespective of the order in which the 2 soy beverages were administered and in apparent correlation with the total isoflavone concentration. There was no significant effect of the soy beverages on serum PSA and p105erbB-2 values.

CONCLUSIONS

This study reveals that short-term exposure of elderly men with elevated serum PSA values to soy protein containing isoflavones decreases serum cholesterol but not the serum biomarkers PSA and p105erbB-2.

A targetable, injectable adenoviral vector for selective gene delivery to pulmonary endothelium in vivo

Adenoviral (Ad) vectors are promising gene therapy vehicles due to their in vivo stability and efficiency, but their potential utility is compromised by their restricted tropism. Targeting strategies have been devised to improve the efficacy of these agents, but specific targeting following in vivo systemic administration of vector has not previously been demonstrated. The distinct aim of the current study was to determine whether an Ad-targeting strategy could maintain fidelity upon systemic vascular administration. We used a bispecific antibody to target Ad infection specifically to angiotensin-converting enzyme (ACE), which is preferentially expressed on pulmonary capillary endothelium and which may thus enable gene therapy for pulmonary vascular disease. Cell-specific gene delivery to ACE-expressing cells was first confirmed in vitro. Administration of retargeted vector complex via tail vein injection into rats resulted in at least a 20-fold increase in both Ad DNA localization and luciferase transgene expression in the lungs, compared to the untargeted vector. Furthermore, targeting led to reduced transgene expression in nontarget organs, especially the liver, where the reduction was over 80%. Immunohistochemical and immunoelectron microscopy analysis confirmed that the pulmonary transgene expression was specifically localized to endothelial cells. Enhancement of transgene expression in the lungs as a result of the ACE-targeting strategy was also confirmed using a new noninvasive imaging technique. This study shows that a retargeting approach can indeed specifically modify the gene delivery properties of an Ad vector given systemically and thus has encouraging implications for the further development of targetable, injectable Ad vectors.

Increase of GKLF messenger RNA and protein expression during progression of breast cancer

Genetic alterations found in carcinomas can alter specific regulatory pathways and provide a selective growth advantage by activation of transforming oncogenes. A subset of these genes, including wild-type alleles of GLI or c-MYC, and activated alleles of RAS or beta-catenin, exhibit transforming activity when expressed in diploid epithelial RK3E cells in vitro. By in vitro transformation of these cells, the zinc finger protein GKLF/KLF-4 was recently identified as a novel oncogene. Although GKLF is normally expressed in superficial, differentiating epithelial cells of the skin, oral mucosa, and gut, expression is consistently up-regulated in dysplastic epithelium and in squamous cell carcinoma of the oral cavity. In the current study, we used in situ hybridization, Northern blot analysis, and immunohistochemistry to detect GKLF at various stages of tumor progression in the breast, prostate, and colon. Overall, expression of GKLF mRNA was detected by in situ hybridization in 21 of 31 cases (68%) of carcinoma of the breast. Low-level expression of GKLF mRNA was observed in morphologically normal (uninvolved) breast epithelium adjacent to tumor cells. Increased expression was observed in neoplastic cells compared with adjacent uninvolved epithelium for 14 of 19 cases examined (74%). Ductal carcinoma in situ exhibited similar expression as invasive carcinoma, suggesting that GKLF is activated prior to invasion through the basement membrane. Expression as determined by Northern blot was increased in most breast tumor cell lines and in immortalized human mammary epithelial cells when these were compared with finite-life span human mammary epithelial cells. Alteration of GKLF expression was confirmed by the use of a novel monoclonal antibody that detected the protein in normal and neoplastic tissues in a distribution consistent with localization of the mRNA. In contrast to most breast tumors, expression of GKLF in tumor cells of colorectal or prostatic carcinomas was reduced or unaltered compared with normal epithelium. The results demonstrate that GKLF expression in epithelial compartments is altered in a tissue-type specific fashion during tumor progression, and suggest that increased expression of GKLF mRNA and protein may contribute to the malignant phenotype of breast tumors.

Immunohistochemical evaluation of global DNA methylation: comparison with in vitro radiolabeled methyl incorporation assay

The in vitro radiolabeled methyl incorporation assay, a commonly used technique to evaluate global methylation of DNA, has some disadvantages and limitations. The purpose of the present study was to compare the results of global DNA methylation evaluated by radiolabeled methyl incorporation (CPM/microg of DNA) with immunohistochemical staining of the same tissue sections with a monoclonal antibody developed against 5-methylcytosine used (5-mc). We archival specimens of squamous cell cancer (SCC) of the human lung with a matched uninvolved specimen (n = 18 pairs) and 18 lung specimens from subjects without lung cancer (noncancer specimens) to make this comparison. The immunostaining for 5-mc was reported as a percentage of cells positive for staining as well as a weighted average of the intensity score. The results suggested that both radiolabeled methyl incorporation assay and immunostaining for 5-mc can be used to demonstrate hypomethylation of DNA in SCC tissues compared to matched uninvolved tissues. An advantage of immunostaining, however, is its ability to demonstrate hypomethylation of SCC compared to adjacent bronchial mucosa on the same archival specimen, obviating the need to use sections from both SCC and matched uninvolved tissues. Only by using the immunostaining technique were we able to document a statistically significant difference in DNA methylation between SCC and noncancer tissues. We conclude that the immunostaining technique has advantages over the radiolabeled methyl incorporation assay and may be best suited for evaluation of global DNA methylation when the methylation status of cancer cannot be normalized by methyl incorporation of normal tissues or when the number of samples available for evaluation is small.

Racial differences in the prognostic usefulness of MUC1 and MUC2 in colorectal adenocarcinomas

There is a need for new prognostic parameters that could add insights into the aggressiveness of tumors. Because the expression of two well-characterized mucin antigens, MUC1 and MUC2, in colorectal adenocarcinomas (CRCs) has been correlated with the aggressiveness of CRCs, we evaluated the prognostic value of the expression of MUC1 and MUC2 in CRCs collected from African-American and Caucasian patients. Expression of MUC1 and MUC2 was evaluated by immunohistochemistry in 166 archival CRC specimens collected from 58 African-American and 108 Caucasian patients that had been analyzed previously for nuclear accumulation of p53 (p53nac). Univariate Kaplan-Meier and multivariate Cox proportional hazards models were used to determine the prognostic significance of expression of MUC1 and MUC2 in these CRCs. MUC1 expression was more frequent in advanced stage CRCs, whereas MUC2 expression was higher in the mucinous type of CRCs. Although similar proportions of CRCs from African-Americans and Caucasians expressed MUC1 and MUC2, the MUC1 expression was found to be an indicator of high risk of death from CRC in Caucasians (hazard ratio, 2.03; P = 0.038) but not in African-Americans. Furthermore, Caucasians with CRCs exhibiting concomitant expression of MUC1 and p53nac demonstrated the lowest probability of overall survival (log rank test, P = 0.004). No prognostic value was found for MUC2 alone or in combination with p53nac in either group of patients. Expression of MUC1 in CRCs is a valuable indicator of poor prognosis in Caucasian patients. Additionally, combined evaluation of MUC1 and p53nac increases the ability to identify Caucasian patients with aggressive subtypes of CRC and may be useful in selecting or in developing novel therapeutic regimes.

Bcl-2 expression is associated with improved prognosis in patients with distal colorectal adenocarcinomas

Several recent studies have suggested that the anatomic location of the tumor and ethnicity of the patient should be considered in the evaluation of prognostic markers of colorectal neoplasia. The phenotypic expression of Bcl-2 has been reported to be a useful prognostic marker in colorectal adenocarcinoma (CRC). However, its prognostic importance in CRCs based on their anatomic location and on the ethnicity of the patients has not been reported. Therefore, we evaluated Bcl-2 expression by immunohistochemistry in CRCs collected from 107 African-American and 149 Caucasian patients from a southern U.S. population. In univariate Kaplan-Meier survival analyses, Bcl-2 expression was associated with better overall survival of both African-American (log-rank, p = 0.040) and Caucasian (log-rank, p = 0.032) patients with distal but not with proximal CRCs. In multivariate Cox regression analyses, when the pathologic features of tumors were not included, the expression of Bcl-2 was associated with better survival in either ethnic patient populations with distal CRCs after adjusting for other confounding variables and p53(nac) status; however, it was not significant in either race when tumor stage was included in multivariate analyses. Thus, these studies suggest that the expression of Bcl-2 in CRCs is a valuable indicator of good prognosis in either race when CRCs are located in the distal colorectum. Also, these studies suggest that the expression of Bcl-2 is useful in determining prognosis before pathologic-clinical staging and it can aid in selection of treatment after evaluation of diagnostic biopsy specimens of patients with distal colorectal adenocarcinomas.

Methods of antigen recovery vary in their usefulness in unmasking specific antigens in immunohistochemistry

Microwave heating of histologic sections in citrate buffer (MAR) is a widely used method of antigen recovery but often results in loss of tissue sections. Low-temperature antigen retrieval (LTAR), incubation at 80 degrees C in citrate buffer for 2 hours with trypsin pretreatment is an alternative method reported to result in better antigen recovery for specific antigens as well as decreased loss of tissue sections. To optimize our immunohistochemical evaluation of breast carcinomas, we compared the efficacy of these methods of antigen recovery for several important antigens. Ten breast carcinomas were immunostained for estrogen and progesterone receptors (ER and PR), Ki-67/ MIB 1, p27/Kip-1, and Bcl-2 after MAR, LTAR with enzymatic pretreatment, or no antigen recovery. The immunohistochemical staining was scored and compared for each antibody and antigen recovery combination. The proportion of tissue lost from each slide after staining also was assessed. More and stronger positive staining was achieved with antibodies to Ki67/MIB 1 and ER when LTAR was used compared with the other two methods; in contrast, optimal staining with antibodies to Bcl-2 was achieved when MAR was used. Staining with anti-p27/Kip- was nearly equal with either LTAR or MAR. Staining with anti-PR was slightly better with MAR than with LTAR. Tissue loss was greatest for MAR compared with LTAR or with no antigen recovery. For selected cases, LTAR caused focal tissue damage, and either the immunostaining with LTAR had to be repeated or only a portion of some tissue sections would be used for examination. LTAR was the most effective for ER and Ki-67/MIB 1. MAR provided the most intense staining for Bcl-2 and PR, but this enhanced staining must be weighed against the greater tissue section loss from MAR. This study demonstrated that AR methods are not equally applicable to all antibodies.

The expression of fatty acid synthase (FASE) is an early event in the development and progression of squamous cell carcinoma of the lung

Correlation of elevated levels of the lipogenic enzyme, fatty acid synthase (FASE), with advanced stages of some cancers has drawn attention to this enzyme as a possible marker of poor prognosis. Because recent studies have shown that cancer cells are dependent on fatty acid synthetic activity and pharmacologic inhibitors of this enzyme are selectively cytotoxic to cancer cells, expression of FASE also may provide a potential target for intervention in the neoplastic process. To determine the potential usefulness of expression of FASE in the neoplastic process of the lung, we evaluated its pattern of expression immunohistochemically in archival specimens from 60 human lung specimens with squamous cell cancer (SCC) and associated "preneoplastic" lesions compared with its expression in the normal bronchial epithelium of 60 noncancer specimens. The expression of FASE was significantly higher in SCC associated uninvolved bronchial epithelium (mean = 0.40+/-0.03, median = 0.38) compared with its expression in the bronchial epithelium of noncancer specimens (mean = 0.18+/-0.02, median = 0.16) indicating its early expression. We also observed a statistically significant step-wise increase in FASE expression from SCC associated uninvolved bronchial epithelium (mean = 0.40+/-0.03, median = 0.38) to epithelial hyperplasia (0.58+/-0.04, median = 0.57) to SCC (1.53+/-0.06, median = 1.50). The results suggested that expression of FASE is an early event in the development and progression of SCC of the lung. The inhibition of fatty acid synthesis by inhibiting enzymatic function with metabolic analogues may be a useful strategy in the treatment of SCCs. The expression of FASE in early lesions such as SCC associated uninvolved bronchial epithelium and epithelial hyperplasia might also provide a potential means for intervention early in the neoplastic process in the lung or even preventing their malignant transformation to invasive carcinomas.

Midkine promoter-based adenoviral vector gene delivery for pediatric solid tumors

It is important to develop a system to express therapeutic genes in tumor cells with sufficient selectivity for cancer gene therapy. Midkine (MK) is a newly identified heparin-binding growth factor that is transiently expressed in the early stages of retinoic acid-induced differentiation of embryonal carcinoma cells. It has been reported that many human malignant tumors express high levels of MK mRNA or protein. However, no MK expression is detected in human or mouse liver. These interesting features of MK led us to examine the MK promoter as a candidate for tumor-specific gene expression. We thus developed new recombinant adenoviral (Ad) vectors containing either luciferase reporter gene (AdMKLuc) or herpes simplex thymidine kinase gene (AdMKTK) under the control of the human MK promoter. AdMKLuc achieved relatively high activity in Wilms' tumor (G-401) and neuroblastoma (SK-N-SH) cell lines. In addition, AdMKTK induced marked cell death in response to ganciclovir (GCV) in these same lines. Conversely, very low activity of the MK promoter was observed in mouse liver in vivo compared with the cytomegalovirus promoter. Importantly, AdMKTK + GCV did not induce liver toxicity, whereas substantial toxicity was seen with AdCMVTK + GCV treatment. On the basis of these findings, we conclude that the MK promoter is a candidate tumor-specific promoter for Wilms' tumor or neuroblastoma.

The accumulation of ascorbic acid by squamous cell carcinomas of the lung and larynx is associated with global methylation of DNA

BACKGROUND

Cigarette smokers are known to have lower concentrations of circulating ascorbic acid than nonsmokers. In contrast, there is evidence that the extracellular fluid lining of the alveolus, which comes in close contact with cigarette smoke, and the alveolar macrophages of smokers are enriched with ascorbic acid. The clinical significance of these observations is unknown.

METHODS

The authors measured the ascorbic acid concentrations and radiolabeled methyl incorporation (which is inversely related to the degree of DNA methylation in vivo) of paired samples of squamous cell carcinoma (SCC) and adjacent uninvolved mucosa of the lung and larynx (n = 22).

RESULTS

Cancerous tissues had significantly higher ascorbic acid concentrations (mean +/- standard deviation [SD, 485 +/- 77; median, 483 ng/mg protein) compared with their matched uninvolved tissues (mean +/- SD, 151 +/- 52; median, 72 ng/mg protein; P < 0.0001). The radiolabeled methyl incorporation was significantly higher in cancerous tissues (mean +/- SD, 31,419 +/- 2629; median, 31,416 counts per minute [CPM]/microg DNA) compared with their matched uninvolved tissues (mean +/- SD, 11,883 +/- 1567; median, 11,444 CPM/microg DNA; P < 0.0001). The Spearman correlation between ascorbic acid concentrations and radiolabeled methyl incorporation by DNA in SCCs was inverse and statistically significant (r = -0.58, P = 0.008), indicating a beneficial effect of accumulated ascorbic acid in global methylation of DNA. In the uninvolved tissues, this correlation was inverse but statistically not significant (r = -0.20, P =0.35).

CONCLUSIONS

Cancerous tissues of the lung and larynx demonstrated their ability to accumulate ascorbic acid. The accumulation of ascorbic acid by these tissues seemed to facilitate global methylation of DNA.

Longitudinal analysis of mammary cancer multiplicity in chemoprevention studies

BACKGROUND

The effect of chemopreventive agents on cancer multiplicity is of primary interest in animal studies. The nature of data collected from chemoprevention studies may be analyzed by a longitudinal analysis of repeatedly measured cancer multiplicity data.

METHODS

We determined the number of mammary cancers over the entire follow-up period for varying doses of two chemopreventive agents. Longitudinal analyses were performed to model the number of cancers over different time intervals.

RESULTS

There was a significant increase in the number of cancers between six to seven weeks post-carcinogen administration in the control group. Varying patterns of cancer development were observed at different doses of chemopreventive agents including a delay in onset of tumor growth compared to the control group.

CONCLUSION

Longitudinal data analysis complements traditional analyses by providing detailed information regarding the effect of chemopreventive agents on the pattern of tumor development throughout the follow-up period. Importantly, some chemopreventive agents may delay time to appearance of mammary cancers without causing a significant difference in cancer multiplicity.

Fractionated radiation therapy in combination with adenoviral delivery of the cytosine deaminase gene and 5-fluorocytosine enhances cytotoxic and antitumor effects in human colorectal and cholangiocarcinoma models

Radiosensitization of human gastrointestinal tumors by 5-fluorouracil (5-FU) has been studied in vitro and clinically in human cancer therapy trials. The bacterial enzyme cytosine deaminase (CD) converts the nontoxic prodrug 5-fluorocytosine (5-FC) into 5-FU. Human colon cancer cells stably expressing CD have been shown by other investigators to be sensitized to radiation following treatment with 5-FC. We previously used an adenoviral vector under control of the cytomegalovirus promoter (AdCMVCD) encoding the CD gene in combination with 5-FC and a single fraction of radiation exposure to enhance cytotoxicity to human cholangiocarcinoma cells in vitro and in vivo. The purpose of this study was to determine whether AdCMVCD infection and 5-FC with multiple fraction low-dose radiotherapy results in enhanced cytotoxicity. In the present study, we utilized AdCMVCD and 5-FC with single fraction radiotherapy to demonstrate enhanced cytotoxicity to WiDr human colon carcinoma cells in vitro. Additionally, we tested this gene therapy/prodrug treatment strategy employing a fractionated radiation dosing schema in animal models of WiDr colon carcinoma and SK-ChA-1 cholangiocarcinoma. A prolonged WiDr tumor regrowth delay was obtained with AdCMVCD infection in combination with systemic delivery of 5-FC and fractionated external beam radiation therapy compared with control animals treated without radiation, without 5-FC, or without AdCMVCD. The results of treatment with AdCMVCD + 5-FC + radiation therapy to cholangiocarcinoma xenografts were equivalent to those obtained with systemic 5-FU administration + radiation. Thus, the use of AdCMVCD can be effectively combined with clinically relevant 5-FC and radiation administration schemes to achieve enhanced tumor cell killing and increased control of established tumors of human gastrointestinal malignancies.

Noninvasive monitoring of gene transfer using a reporter receptor imaged with a high-affinity peptide radiolabeled with 99mTc or 188Re

Gene therapy protocols require better modalities to monitor the location and level of transferred gene expression. One potential in vivo mechanism to assess gene expression would be to image the binding of a radiolabeled peptide to a reporter receptor that is expressed in targeted tissues. This concept was tested in a tumor model using a replication-incompetent adenoviral vector encoding the human type 2 somatostatin receptor (Ad5-CMVhSSTr2). Expression of the hSSTr2 reporter was imaged using a radiolabeled, somatostatin-avid peptide (P829).

METHODS

Bilateral subcutaneous A427 tumor xenografts were established on the flanks of athymic nude mice. These human-origin, non-small cell lung tumors are normally negative for hSSTr2 expression. One tumor was injected directly with Ad5-CMVhSSTr2, whereas the second tumor was injected directly with a control Ad5 vector. The mice were injected intravenously 48 h later with P829 peptide that was radiolabeled to high specific activity with 99mTc (half-life, 6 h) or 188Re (half-life, 17 h). Tumors were frozen and evaluated for somatostatin receptor expression using fluorescein-labeled somatostatin.

RESULTS

The accumulation of radiolabeled P829 in hSSTr2-expressing tumors was easily visualized by gamma camera imaging 3 h after injection. Imaging region of interest analyses and biodistribution studies confirmed a 5- to 10-fold greater accumulation of both radiolabeled P829 peptides in the Ad5-CMVhSSTr2-injected tumors versus control tumors injected with control Ad5 vectors. Ad5-CMVhSSTr2-injected tumors accumulated 2.5-3.8 percentage injected dose per gram 3 h after injection. Only Ad5-CMVhSSTr2-injected tumors expressed somatostatin receptors, as determined by immunohistochemistry.

CONCLUSION

These studies show the feasibility of imaging a 99mTc-labeled peptide's binding to a reporter receptor after in vivo gene transfer to tumor cells. The 188Re-labeled peptide worked equally well for this imaging approach and offers the additional advantage of energetic beta decay with potential therapeutic efficacy. 99mTc and 188Re are generator produced, an advantage for widespread availability and low cost, and both radioisotopes can be imaged with existing, high-resolution modalities. There is great potential for using 99mTc-labeled peptides for imaging gene transfer with the hSSTr2 reporter receptor, especially when the reporter correlates with the expression of therapeutic genes that can be included simultaneously in the gene therapy vector.

The expression of Ep-CAM (17-1A) in squamous cell cancers of the lung

Immunotherapy trials using monoclonal antibodies 323/A3 and 17-1A that recognize Ep-CAM, including trials focused on cancer of the lung, currently are underway. Nevertheless, there have been few comprehensive evaluations of the expression of Ep-CAM in specific types of neoplastic processes, including cancer of the lung. The current study of 60 human subjects with squamous cell cancer (SCC) of the lung, selected at random, was undertaken (1) to examine the expression of Ep-CAM in SCC and associated uninvolved bronchial mucosa, bronchial epithelial hyperplasia, and dysplasia, and (2) to correlate the results with established prognostic indicators and survival of patients. In both the uninvolved bronchial mucosa and epithelial hyperplasia, the expression of Ep-CAM in luminal cells was significantly higher compared with its expression in the matched basal cells (P = .003, P < .0001, respectively). When Ep-CAM scores of basal and luminal cells present in uninvolved bronchial mucosa and epithelial hyperplasia were combined, we observed a statistically significant stepwise increase in Ep-CAM expression from uninvolved bronchial mucosa to epithelial hyperplasia to SCC, suggesting its involvement in malignant transformation of SCC. The expression of Ep-CAM was significantly higher in poorly to moderately differentiated SCC compared with well-differentiated SCC (P = .04). An increase in the expression of Ep-CAM with increasing size or local extent of the primary tumor approached statistical significance (P = .09). The expression of Ep-CAM increased significantly with increasing involvement of regional lymph nodes (P = .02). Similarly, the expression of Ep-CAM increased with the increasing TNM stages (P = .04). Kaplan-Meier Survival analysis using the same categorizations showed that increasing tumor size, nodal status, and stage were significantly associated with poor patient survival (P = .04, .01, .01, respectively). There was, however, no statistically significant association between patient survival and staining intensity of carcinomas for Ep-CAM. We conclude that expression of Ep-CAM increased during the progression of SCC of the lung and, therefore, may play a role in the carcinogenesis of this disease.

The p44S10 locus, encoding a subunit of the proteasome regulatory particle, is amplified during progression of cutaneous malignant melanoma

Gene amplification is frequently present in human tumors, although specific target genes relevant to many amplified loci remain unidentified. An expression cloning assay enabled identification of a candidate oncogene derived from human chromosome 3p14.1. The cDNA retrieved from morphologically transformed cells contained the full-length protein coding region and detected an abundant transcript in the same cells. Sequence analysis revealed identity with the wild-type sequence of p44S10, a highly conserved subunit of the 26S proteasome that exhibits similarity to the Arabidopsis fus6/cop11 family of signaling molecules. p44S10 gene copy number and mRNA expression were increased in association with segmental 1.8 - 11-fold chromosomal gains in cutaneous malignant melanoma cell lines (5/13; 40%) and tumors (2/40; 5%), and in breast cancer MCF-7 cells. Likewise, malignant progression of human radial growth phase WM35 melanoma cells was associated with amplification and increased expression of endogenous p44S10, and increased expression of p44S10 was sufficient to induce proliferation of WM35 cells in vivo. The results demonstrate segmental copy number gains within chromosome 3p in cutaneous malignant melanoma and suggest that deregulation of a proteasome regulatory particle subunit may contribute to the malignant phenotype.

Combined modality therapy of A431 human epidermoid cancer using anti-EGFr antibody C225 and radiation

BACKGROUND

Monoclonal antibodies (mAb) to epidermal growth factor receptor (EGFr) inhibit tumor cell proliferation and enhance cytotoxicity of chemotherapeutic agents. The purpose of this study was to investigate the interaction of the anti-EGFr antibody C225 combined with radiotherapy (RT) on EGFr expressing A431 human epidermoid cancer cells.

METHODS

Cell proliferation, apoptosis, EGFr expression and phosphorylation, and clonogenic survival were assayed in vitro. A431 tumor growth inhibition and immunohistochemistry analysis of EGFr expression and apoptosis were assessed in vivo.

RESULTS

C225 plus RT produced greater inhibition of A431 cell proliferation than C225 or RT alone which was corroborated by enhanced apoptosis. Similar clonogenic survival occurred following the addition of C225 to RT, although colonies were smaller in the presence of C225. C225 produced inhibition of EGF-induced phosphorylation of EGFr without concurrent down-regulation of surface receptor, which was not altered by RT. Combined treatment of mice bearing tumors demonstrated enhancement of complete regressions, reduction in time to tumor size doubling, and prolongation of survival. Significant apoptosis occurred in xenograft tumors treated with C225 with or without RT.

CONCLUSIONS

These data demonstrate an interaction between C225 and RT. C225-mediated apoptosis and inhibition of EGFr phosphorylation may be critical in the interaction. Studies to define the precise influence of combined modality treatment on the EGFr signal transduction cascade need to be pursued. The combination of growth factor receptor antibodies and RT has potential application in clinical oncology.

Phase II study of interferon-enhanced 131I-labeled high affinity CC49 monoclonal antibody therapy in patients with metastatic prostate cancer

Adjuvant Interferon (IFN) was given to increase tumor antigen expression and enhance localization with 131I-labeled CC49 radioimmunotherapy in a Phase II trial for hormone resistant metastatic prostate cancer. Patients received four doses of alpha-IFN (3 x 10(6) IU) s.c. on alternate days, from day -5 to day +1 of 75 mCi/m2 131I-CC49 treatment. Toxicity was well tolerated, with the majority of patients experiencing transient grade 3 or 4 neutropenia and/or thrombocytopenia (maximal at 4-6 weeks). The absorbed dose was >25 Gy in four of eight tumors visualized, which represents an increase of >20 fold over whole body radiation dose. Two patients had radiographic minor responses by 6 weeks post-therapy, whereas five of six patients experiencing pain had symptom relief without radiographic changes. The protocol provided modest antitumor effects (pain relief in five of six patients and two minor radiographic responses). This study suggests that the addition of IFN enhanced tumor uptake and antitumor effects as compared to a prior Phase II trial of 131I-CC49 alone.

Ep-Cam levels in prostatic adenocarcinoma and prostatic intraepithelial neoplasia

PURPOSE

The monoclonal antibody (mAb) 323/A3, a second generation high affinity antibody of the 17-1A antibody family, recognizes a 40 kDa transmembrane glycoprotein that has been referred to as Ep-CAM, 17-1A recognized antigen, or EGP40. While Ep-CAM is expressed on the basolateral surface of a variety of epithelia, the strongest expression is frequently detected among several types of carcinoma. In this regard, Ep-CAM may be useful in therapy, in diagnosis, and/or in prognosis. We examined the distribution of Ep-CAM in normal, dysplastic, and malignant prostatic epithelium.

MATERIALS AND METHODS

Paraffin sections of prostate tissue from 76 patients with clinically localized (pT2) prostatic adenocarcinoma were immunostained with mouse mAb 323/A3 using the avidin-biotin horseradish peroxidase method.

RESULTS

Within benign prostatic epithelium, immunoreactivity typically was low and frequently was restricted to the luminal cells. In contrast, moderate to strong immunostaining was detected frequently in the luminal cells of high grade prostatic intraepithelial neoplasia (PIN). Furthermore, strong immunostaining usually was detected in the cells of adenocarcinomas. The immunostaining in PIN (p<0.0001) and in adenocarcinoma (p<0.0001) was significantly greater than that observed in the normal epithelium. Expression of Ep-CAM did not vary significantly with the Gleason score of tumors or the clinical outcome of patients. Expression of Ep-CAM was demonstrated also in the malignant prostatic cell lines LNCaP, DU145 and PC3 using immunohistochemistry and an immunoblot technique.

CONCLUSIONS

These findings suggest that increased levels of Ep-CAM represent an early event in the development of prostatic adenocarcinoma.

Transforming growth factor alpha (TGF-alpha) expression in dysplastic oral leukoplakia: modulation by 13-cis retinoic acid

BACKGROUND

Surrogate endpoint biomarkers (SEBs) are detectable molecular, cellular, and tissue changes that take place during tumorigenesis and can be modulated by a chemoprevention agent.

METHOD

To identify candidate SEBs for invasive squamous cell carcinoma of the upper aerodigestive tract (SCC), we have studied the expression of transforming growth factor-alpha (TGF-alpha) and epidermal growth factor receptor (EGFr) in sequential biopsy specimens of dysplastic oral leukoplakia and adjacent normal-appearing mucosa. Biopsies were taken from patients before, during, and after treatment with 13-cis retinoic acid, a vitamin A derivative. Immunohistochemistry was performed using the Biogenex Super Sensitive Biotin-Streptavidin horseradish peroxidase detection system.

RESULTS

The pretreatment expression of TGF-alpha and EGFr in dysplastic oral leukoplakia was increased when compared with their expression in adjacent normal-appearing mucosa (p = 0.001 and p = 0.01, respectively). Eleven of 14 patients enrolled in the study (78.6%) completed 3 months of treatment with 13-cis retinoic acid (1. 0 mg/kg/day). TGF-alpha expression in dysplastic oral leukoplakia, but not in adjacent normal-appearing mucosa, decreased during treatment (p < 0.05).

CONCLUSIONS

TGF-alpha is a candidate SEB for future SCC chemoprevention trials.

Androgenic regulation of growth factor and growth factor receptor expression in the CWR22 model of prostatic adenocarcinoma

The effects of androgen manipulation on epidermal growth factor (EGF) receptor, p185erbB-2 and transforming growth factor-alpha (TGF-alpha) levels were examined in prostatic adenocarcinoma. Male nude mice were inoculated with the CWR22 androgen-dependent human prostatic tumor or an androgen-independent (CWR22R) derivative. Mice with CWR22 tumors were castrated and subsequently killed at 3, 7, 21, 28 or 42 days post-castration. Other CWR22-bearing mice received s.c. testosterone pellets at 21 days post-castration and were killed 7 days later. EGF receptor, p185erbB-2 and TGF-alpha levels were examined by immuno-histochemistry. Strong EGF receptor and p185erbB-2 immunostaining was detected in CWR22 tumors from intact controls. EGF receptor immunostaining decreased by 65% to 70% at 21 to 42 days post-castration. Testosterone treatment at 21 to 28 days post-castration resulted in a 2-fold increase in EGF receptor immunostaining. p185erbB-2 immunostaining within CWR22 tumors did not decrease following castration and, in fact, was slightly increased at 7 days post-castration. The effects of castration on EGF receptor and p185erbB-2 levels were confirmed by Western blot analysis. Fewer than 10% of CWR22 tumor cells demonstrated strong TGF-alpha immunostaining, and androgen manipulation did not effect TGF-alpha immunostaining. In contrast, 30% of androgen-independent CWR22R tumor cells were strongly immunostained for TGF-alpha. Our findings indicate that EGF receptor levels, but not p185erbB-2 levels, are strongly dependent on testosterone in CWR22 tumors. The co-localization of TGF-alpha and the EGF receptor in CWR22R tumors suggests that these factors may constitute an autocrine pathway that regulates androgen-independent growth.