MALDI Imaging Combined with Laser Microdissection-Based Microproteomics for Protein Identification: Application to Intratumor Heterogeneity Studies

Matrix-assisted laser desorption ionization (MALDI) imaging is widely used for in situ proteomic mapping and finds multiple applications in pathology. However, low fragmentation yields in MALDI avoid an optimal identification of peptides from tissues. On the other hand, LMD-based microproteomic analyses allow for the identification of hundreds to thousands of proteins from small tissue regions. Herein, we present the combination of MALDI imaging and LMD-based microproteomic approaches for parallel identification. We illustrate the workflow with an application to intratumor heterogeneity studies.

An Improved Molecular Histology Method for Ion Suppression Monitoring and Quantification of Phosphatidyl Cholines During MALDI MSI Lipidomics Analyses

Tissue lipidomics is one of the latest omics approaches for biomarker discovery in pharmacology, pathology, and the life sciences at large. In this context, matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) is the most versatile tool to map compounds within tissue sections. However, ion suppression events occurring during MALDI MSI analyses make it impossible to use this method for quantitative investigations without additional validation steps. This is especially true for lipidomics, since different lipid classes are responsible for important ion suppression events. We propose here an improved lipidomics method to assess local ion suppression of phospatidylcholines in tissues. Serial tissue sections were spiked with different amounts of PC(16:0 d31/18:1) using a nebulization device. Settings for standard nebulization were strictly controlled for a detection similar to when using spiked tissue homogenates. The sections were simultaneously analyzed by MALDI MSI using a Fourier transform ion cyclotron resonance analyzer. Such a spray-based approach allows taking into account the biochemical heterogeneity of the tissue for the detection of PC(16:0 d31/18:1). Thus, here we present the perspective to use this method for quantification purposes. The linear regression lines are considered as calibration curves and we calculate PC(16:0/18:1) quantification values for different ROIs. Although those values need to be validated by a using a different independent approach, the workflow offers an insight into new quantitative mass spectrometry imaging (q-MSI) methods. This approach of ion suppression monitoring of phosphocholines in tissues may be highly interesting for a large range of applications in MALDI MSI, particularly for pathology using translational science workflows.

Abstract LB-187: MALDI imaging-guided microproteomics workflow for intratumor heterogeneity studies

A single tumoral tissue can bear phenotypically different cell populations. This phenomenon called intra-tumor heterogeneity can lead to differential behaviors regarding metastasis seeding and therapy resistance [1]. MALDI imaging has proven its efficiency for revealing hidden molecular features offering an insight into distinct cellular regions based on their molecular content. Further, proteomics applied to these regions could allow depicting the molecular context associated to particular cells groups and enable the collection of qualitative, quantitative and spatial information for each protein.

Breast cancer Formalin Fixed and Paraffin Embedded (FFPE) tissues, from patients whose outcome had been recorded over a period of 10 years, were used for this study. After Citric Acid Antigen Retrieval and trypsin digestion, images were obtained by MALDI-TOF/TOF-MS (Bruker, Germany). Analytical data analysis were applied to the measured large normalized datasets using the cloud software Multimaging (ImaBioTech, France) in order to find potential biomarkers that could be correlated to different patient survivals.

Small tissue areas were obtained by laser microdissection (LEICA LMD 700, Germany), upon which a combination of chemical processes was applied to ensure optimal protein antigen retrieval, extraction and digestion. Finally, the tissue pieces obtained were analyzed by LC-MS/MS using UPLC Waters Nanoacquity and Thermo Q-Exactive instruments.

Based on mathematical calculations carried out on the MALDI imaging datasets, ROIs could be detected in a single tumor. We aimed to compare the proteomic profiles of these intra-tumoral ROIs for several MALDI datasets. Recently, Longuespée [2] published a method to retrieve the identification of more than 1400 proteins from microdissected tissue pieces containing only 2700 cells. This whole procedure allowed us to identify a panel of proteins that characterizes tissue heterogeneity within a single tumor and to associate their presence with the information of each patient, such as their prognosis. This proves the applicability of the combination of MALDI imaging for the discovery of tumoral heterogeneity without a priori, on a mathematical basis, and classical proteomics applied on laser-microdissected tissue samples of very restricted areas. This way, we will be able to retrieve the extensive molecular context associated to a bad patient prognosis and/or therapy resistance.

The described workflow combines the unique advantages of MALDI imaging for de novo molecular feature characterization and LMD-based microproteomics. It offers the possibility to identify protein/peptide markers that will have the power to predict the outcome of the breast cancer patient at the beginning of their treatment, and thus, improve the clinical care for the benefit of the patients.

[1] Zardavas et al., Nature Rev. Clin. Onc. (2015)

[2] Longuespée et al., Methods (2015)

Citation Format: Deborah Alberts, Rémi Longuespée, Charles Pottier, Nicolas Smargiassio, Gabriel Mazzucchelli, Dominique Baiwir, Philippe Delvenne, Gregory Hamm, Stefan Linehan, Fabien Pamelard, Gael Picard de Muller, Edwin De Pauw. MALDI imaging-guided microproteomics workflow for intratumor heterogeneity studies. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr LB-187.

Fyn is a redox sensor involved in solar ultraviolet light-induced signal transduction in skin carcinogenesis

Solar ultraviolet (UV) light is a major etiological factor in skin carcinogenesis, with solar UV-stimulated signal transduction inducing pathological changes and skin damage. The primary sensor of solar UV-induced cellular signaling has not been identified. We use an experimental system of solar simulated light (SSL) to mimic solar UV and we demonstrate that Fyn is a primary redox sensor involved in SSL-induced signal transduction. Reactive oxygen species (ROS) generated by SSL exposure directly oxidize Cys488 of Fyn, resulting in increased Fyn kinase activity. Fyn oxidation was increased in mouse skin after SSL exposure, and Fyn knockout (Fyn^−/−) mice formed larger and more tumors compared to Fyn wildtype mice when exposed to SSL for an extended period of time. Murine embryonic fibroblasts (MEFs) lacking Fyn as well as cells in which Fyn expression was knocked down were resistant to SSL-induced apoptosis. Furthermore, cells expressing mutant Fyn (C448A) were resistant to SSL-induced apoptosis. These findings suggest that Fyn acts as a regulatory nexus between solar UV, ROS and signal transduction during skin carcinogenesis.

A laser microdissection-based workflow for FFPE tissue microproteomics: Important considerations for small sample processing

Proteomic methods are today widely applied to formalin-fixed paraffin-embedded (FFPE) tissue samples for several applications in research, especially in molecular pathology. To date, there is an unmet need for the analysis of small tissue samples, such as for early cancerous lesions. Indeed, no method has yet been proposed for the reproducible processing of small FFPE tissue samples to allow biomarker discovery. In this work, we tested several procedures to process laser microdissected tissue pieces bearing less than 3000 cells. Combined with appropriate settings for liquid chromatography mass spectrometry-mass spectrometry (LC-MS/MS) analysis, a citric acid antigen retrieval (CAAR)-based procedure was established, allowing to identify more than 1400 proteins from a single microdissected breast cancer tissue biopsy. This work demonstrates important considerations concerning the handling and processing of laser microdissected tissue samples of extremely limited size, in the process opening new perspectives in molecular pathology. A proof of the proposed method for biomarker discovery, with respect to these specific handling considerations, is illustrated using the differential proteomic analysis of invasive breast carcinoma of no special type and invasive lobular triple-negative breast cancer tissues. This work will be of utmost importance for early biomarker discovery or in support of matrix-assisted laser desorption/ionization (MALDI) imaging for microproteomics from small regions of interest.

Use of radiofrequency power to enable glow discharge optical emission spectroscopy ultrafast elemental mapping of combinatorial libraries with nonconductive components: nitrogen-based materials

Combinatorial chemistry and high-throughput techniques are an efficient way of exploring optimal values of elemental composition. Optimal composition can result in high performance in a sequence of material synthesis and characterization. Materials combinatorial libraries are typically encountered in the form of a thin film composition gradient which is produced by simultaneous material deposition on a substrate from two or more sources that are spatially separated and chemically different. Fast spatially resolved techniques are needed to characterize structure, composition, and relevant properties of these combinatorial screening samples. In this work, the capability of a glow discharge optical emission spectroscopy (GD-OES) elemental mapping system is extended to nitrogen-based combinatorial libraries with nonconductive components through the use of pulsed radiofrequency power. The effects of operating parameters of the glow discharge and detection system on the achievable spatial resolution were investigated as it is the first time that an rf source is coupled to a setup featuring a push-broom hyperspectral imaging system and a restrictive anode tube GD source. Spatial-resolution optimized conditions were then used to characterize an aluminum nitride/chromium nitride thin-film composition spread. Qualitative elemental maps could be obtained within 16.8 s, orders of magnitude faster than typical techniques. The use of certified reference materials allowed quantitative elemental analysis maps to be extracted from the emission intensity images. Moreover, the quantitative procedure allowed correcting for the inherent emission intensity inhomogeneity in GD-OES. The results are compared to quantitative depth profiles obtained with a commercial GD-OES instrument.

Depth profile characterization of Zn-TiO2 nanocomposite films by pulsed radiofrequency glow discharge-optical emission spectrometry

In recent years particular effort is being devoted towards the development of radiofrequency (rf) pulsed glow discharges (GDs) coupled to optical emission spectrometry (OES) for depth profile analysis of materials with technological interest. In this work, pulsed rf-GD-OES is investigated for the fast and sensitive depth characterization of Zn-TiO(2) nanocomposite films deposited on conductive substrates (Ti and steel). The first part of this work focuses on assessing the advantages of pulsed GDs, in comparison with the continuous GD, in terms of analytical emission intensities and emission yields. Next, the capability of pulsed rf-GD-OES for determination of thickness and compositional depth profiles is demonstrated by resorting to a simple multi-matrix calibration procedure. A rf forward power of 75 W, a pressure of 600 Pa, 10 kHz pulse frequency and 50% duty cycle were selected as GD operation parameters.Quantitative depth profiles obtained with the GD proposed methodology for Zn-TiO(2) nanocomposite films, prepared by the occlusion electrodeposition method using pulsed reverse current electrolysis, have proved to be in good agreement with results achieved by complementary techniques, including scanning electron microscopy and inductively coupled plasma-mass spectrometry. The work carried out demonstrates that pulsed rf-GD-OES is a promising tool for the fast analytical characterization of nanocomposite films.

Change in patient weight during platinum/paclitaxel-based chemotherapy for ovarian cancer: A Gynecologic Oncology Group study

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Background: Platinum/paclitaxel (P)-based chemotherapy is current treatment (tx) for advanced epithelial ovarian cancer (EOC). Previous studies suggest this regimen may induce weight change, which is a surrogate for body reaction to tx and may predict quality of life and clinical outcomes. We sought to explore the association between weight change during treatment and survival. Methods: A retrospective data review was conducted of 792 patients who participated in a Gynecologic Oncology Group (GOG) phase III randomized treatment trial (GOG 158) using cisplatin (Cis)/P vs carboplatin (Carbo)/P in optimal stage III EOC. Pretreatment body mass index (BMI) was calculated based on patient height and weight following surgery. Weight change during tx was defined as the ratio of body weight at completion of protocol therapy to pretreatment body weight. Progression-free survival (PFS) and overall survival (OS), classified by BMI or relative weight change, were estimated by Kaplan-Meier, and the associations between BMI, relative weight change and PFS and OS were assessed using Cox model controlled for known prognostic variables. Results: The median BMI was 24.9. There was no significant difference in PFS or OS related to BMI; however, there was a significant relationship between median OS and weight change as follows: >5% decrease = 48.0 months; 0–5% decrease = 49.3 months; 0–5% increase = 61.1 months; and >5% increase = 68.2 months (p = 0.006). The relative risk of death increased by 7% for each 5% decrease in body weight (HR = 0.93, 95% CI = 0.88–0.99; p = 0.013) adjusted for covariates. Results suggest more evident weight loss in the Cis/P arm than the Carbo/P arm during the first cycle of tx (−2.2 kg vs. −1.2 kg), and decreased weight was more likely to return to pretreatment level in the Carbo/P arm. Conclusions: Loss of body weight, but not BMI, during platinum/P-based chemotherapy is an indicator for poor OS in EOC patients. Cis/P may be associated with more weight loss compared to Carbo/P. This exploratory study supports the development of treatment strategies that minimize weight loss-producing toxicities to improve outcomes in this patient population.

No significant financial relationships to disclose.

Survival (S) of ovarian cancer (OC) patients (pts) treated on SWOG9701/GOG178: 12 versus (v) 3 cycles (C) of monthly single-agent paclitaxel (PAC) following attainment of a clinically-defined complete response (CR) to platinum (PLAT)/PAC

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Background: This phase 3 trial was closed by the SWOG Data Safety and Monitoring Committee (DSMC) when a prospectively-defined interim analysis revealed a highly statistically significant difference in progression-free S (PFS) (28 v 21 months [M]; p = 0.0023; hazard ratio [HR] 2.31) (JCO 2003; 21:2460). At study closure, there were insufficient deaths to describe the impact of 12-C of PAC on overall S (OS). Methods: Eligibility included OC or primary peritoneal cancer, attainment of a CR to PLAT/PAC, and ≤ grade 1 neuropathy. Pts entered into the trial (n = 296) received either 12-C or 3-C of PAC (175 mg/m2 q-28 days), and were then observed until progression. Results: Of the 146 pts on the 3-C arm, 9 (6%) actually received prolonged PAC (> 3-C) following closure of the study by the DSMC. Median (12-C v 3-C; intention-to-treat analysis): updated PFS (all pts) 22 v 14 M, p = 0.01; OS (all pts) 53 v 46 M, p = 0.27. Exploratory analysis (Cox models adjusting for stratification factors): 12-C v 3-C HR 0.59 (p = 0.03) if baseline CA-125 ≤ 10 (n = 175), and 1.25 (p = 0.34) for baseline CA-125 >10 (n = 121). The treatment v baseline CA-125 interaction was statistically significant (Cox model p = 0.03). Conclusion: OS was not significantly different between 12-C v. 3-C of PAC, either because (a) treatment at relapse equalized OS; (b) the sample size was insufficient to reveal a difference; (c) the crossover of pts from 3-C to longer treatment masked a potential difference; or (d) treatment was possibly prematurely discontinued at 12-C in pts who had not progressed (suggested by a previously reported exploratory analysis -JCO 2003; 21:2460). Of interest, an exploratory analysis strongly suggested an improvement in S for pts receiving 12-C of PAC if the baseline CA-125 level was ≤10, those individuals likely to have the smallest volume of clinically-undetectable residual OC when single-agent “maintenance” PAC was initiated.

No significant financial relationships to disclose.

Reproducibility and relative validity of a questionnaire to assess intake of black tea polyphenols in epidemiological studies

Epidemiological studies suggest that tea drinking may reduce the risk of cardiovascular diseases and cancers. Although tea is an important source of antioxidant phytochemicals, variation in preparation techniques may translate to variation in antioxidant capacity. However, most large-scale epidemiological studies use regular food frequency questionnaires to estimate tea intake, and nationally available nutrient analysis databases do not include levels of black tea polyphenols. The Arizona Tea Questionnaire (ATQ) was designed as a tool for collecting more complete dietary tea consumption information, and a database was developed after analyzing 40 black tea samples (brewed, instant, and sun tea) for polyphenols. This study assesses the reliability and relative validity of the ATQ and polyphenol database. Relative validity of estimates of black tea consumption was tested by comparing the ATQ with the traditional Arizona Food Frequency Questionnaire and four days of food records. The ATQ was tested for reproducibility of estimates of black (hot and iced) tea consumption and levels of black tea polyphenol intake. Correlations between two measures of intake taken 2 months apart ranged from 0.72 for black hot tea to 0.86 for black sun tea. Mean intakes (range) of total flavonoids for black tea consumers were 80.8 (3.0-588.0) mg/day at the first ATQ and 102.4 (4.5-802.3) mg/day at the second ATQ (r = 0.83, P < 0.001). The ATQ provided highly reproducible estimates of both total tea consumption and individual tea polyphenol intake. This instrument may be a useful tool in studies of the associations between tea consumption, tea polyphenols intake, and risk for chronic disease.

Effect of food on the oral bioavailability of UFT and leucovorin in cancer patients

UFT is composed of tegafur (FT), a prodrug of 5-fluorouracil (5-FU), and uracil in a fixed combination (1:4). In conjunction with leucovorin, UFT is being developed for the first-line oral treatment of metastatic colorectal cancer. The effect of food on the oral bioavailability of UFT (2 x 100 mg capsules; dose in terms of FT) and leucovorin (2 x 15 mg tablets) was evaluated in a single-dose, randomized, two-way crossover study. Patients (n = 25) were assigned to receive both drugs after an overnight fast or 5 min after completion of a high-fat meal (721 calories) with a 3-day washout period between treatments; then they were permitted to continue on oral UFT/leucovorin therapy for safety assessment. UFT (300 mg/m2/day as three divided doses) and leucovorin (90 mg/day as three divided doses) were given for 28 days. After a 7-day rest, the 28-day cycle was repeated. Pharmacokinetics (n = 22 patients) were determined for FT, 5-FU, uracil, leucovorin, and 5-methyltetrahydrofolate (an active metabolite of leucovorin). The absence of food-effect on peak plasma concentration (CMAX) and the area under the curve (AUC) was concluded if the 90% confidence interval for the ratio of the treatment means was entirely contained in 0.75-1.33. Administration of UFT with food resulted in a 34% decrease in CMAX of FT, whereas the AUC of FT remained unchanged. Food decreased the CMAX and AUC values of uracil and 5-FU by 37-76%. On the contrary, the CMAX and AUC values of leucovorin and 5-methyltetrahydrofolate were increased by 14-60% with food. Time to reach CMAX for all analytes was significantly (P < or = 0.001) delayed by food. Except for the AUCs of FT, the statistical criterion for concluding a lack of food-effect was not met. These data suggest that UFT/leucovorin should not be dosed simultaneously with food. It is recommended that food should not be consumed for 1 h before and after an oral dose of UFT and leucovorin in a manner similar to pivotal Phase III trials. The 28-day oral regimen of UFT and leucovorin was generally well tolerated in the population studied.

Predictors of inactivation and reasons for participant inactivation during a skin cancer chemoprevention study

Maintaining good compliance is a major challenge in long-term cancer chemoprevention trials. Minimizing the number of inactive participants during a trial is an important factor in maximizing compliance. Identifying reasons for and predictors of inactivation is the first step in being able to reduce participant inactivation. In this skin cancer chemoprevention trial, the 2,297 participants were randomized to receive 25,000 IU of retinol daily or a placebo. Median follow-up time was 3.8 years. The reason for inactivation was determined for each participant who stopped taking the study capsules. Six hundred and seventy-seven (29.7%) participants became inactive during the 5-year study. There was no significant difference between the number of participants inactivating by treatment group or sex. The most common reasons for inactivation were illness of subject, spouse, or a close relative (18.6%) and experience of a clinical symptom consistent with vitamin A ingestion (17.1%). Participants in the vitamin A group (10.1%) more frequently cited symptoms coded as "not consistent with vitamin A" as the reason for inactivation compared with those in the placebo group [5.4% (P < 0.05)]. The inactivation rate was highest in the first month of the trial and declined thereafter. A low education level (hazard ratio, 1.59) and unmarried status (hazard ratio, 1.29) were the only significant predictors of inactivation. These findings may be useful in developing targeted strategies to decrease inactivation and thereby increase compliance in future chemoprevention trials. However, these findings need to be confirmed because published research in this area is very limited.

Molecular classification of cutaneous malignant melanoma by gene expression profiling

The most common human cancers are malignant neoplasms of the skin. Incidence of cutaneous melanoma is rising especially steeply, with minimal progress in non-surgical treatment of advanced disease. Despite significant effort to identify independent predictors of melanoma outcome, no accepted histopathological, molecular or immunohistochemical marker defines subsets of this neoplasm. Accordingly, though melanoma is thought to present with different 'taxonomic' forms, these are considered part of a continuous spectrum rather than discrete entities. Here we report the discovery of a subset of melanomas identified by mathematical analysis of gene expression in a series of samples. Remarkably, many genes underlying the classification of this subset are differentially regulated in invasive melanomas that form primitive tubular networks in vitro, a feature of some highly aggressive metastatic melanomas. Global transcript analysis can identify unrecognized subtypes of cutaneous melanoma and predict experimentally verifiable phenotypic characteristics that may be of importance to disease progression.

Novel peptidomimetic hematoregulatory compounds

The activity of a novel series of peptidomimetic hematoregulatory compounds, designed based on a pharmacophore model inferred from the structure activity relationships of a peptide SK&F 107647 (1), is reported. These compounds induce a hematopoietic synergistic factor (HSF) which in turn modulates host defense. The compounds may represent novel therapeutic agents in the area of hematoregulation.

Beta-carotene produces sustained remissions in patients with oral leukoplakia: results of a multicenter prospective trial

BACKGROUND

Beta-Carotene has been reported to produce regressions in patients with oral leukoplakia, a premalignant lesion. However, previous studies have all been of short duration, with clinical response as the end point.

OBJECTIVE

To evaluate the duration of response and the need for maintenance therapy in subjects who respond to beta-carotene.

METHODS

In this multicenter, double-blind, placebo-controlled trial, subjects were given beta-carotene, 60 mg/d, for 6 months. At 6 months, responders were randomized to continue beta-carotene or placebo therapy for 12 additional months.

RESULTS

Fifty-four subjects were enrolled in the trial, with 50 being evaluable. At 6 months, 26 subjects (52%) had a clinical response. Twenty-three of the 26 responders completed the second, randomized phase. Only 2 (18%) of 11 in the beta-carotene arm and 2 (17%) of 12 in the placebo arm relapsed. Baseline biopsies were performed in all patients, with dysplasia being present in 19 (38%) of the 50 evaluable patients. A second biopsy was obtained at 6 months in 23 subjects who consented to this procedure. There was improvement of at least 1 grade of dysplasia in 9 (39%), with no change in 14 (61%). Nutritional intake was assessed using food frequency questionnaires. There was no change in carotenoid intake during the trial. Responders had a lower intake of dietary fiber, fruits, folate, and vitamin E supplements than did nonresponders. Beta-carotene levels were measured in plasma and oral cavity cells. Marked increases occurred during the 6-month induction. However, baseline levels were not restored in subjects taking placebo for 6 to 9 months after discontinuation of beta-carotene therapy.

CONCLUSIONS

The activity of beta-carotene in patients with oral leukoplakia was confirmed. The responses produced were durable for 1 year.

Highly simplified method for gas-liquid chromatographic quantitation of bile acids and sterols in human stool

A simple method for the gas-liquid chromatographic quantitation of human fecal bile acids and sterols is described where bile acids are subjected to n-butyl ester derivatization, without prior isolation from the stool, followed by trimethylsilylation of the sterols and bile acids. Under these conditions, bile acid derivatives are well resolved from each other and from the trimethylsilyl ether derivatives of fecal sterols and no overlap occurs. The method was shown to be highly reproducible and recoveries were similar to those obtained with other methods used for fecal bile acid analysis. Application of the method for bile acid and sterol analysis in human stool is described.

Chromosome abnormalities in ovarian adenocarcinoma: II. Prognostic impact of nonrandom chromosome abnormalities in 244 cases

In a large series of ovarian carcinomas from 244 patients, 134 cases had chromosome rearrangements. We showed before that the pattern of chromosome breakpoints involved 21 separate chromosome regions nonrandomly and, in 90% of cases with breaks, the breakpoints occurred within 13 commonly involved regions. Log-rank and proportional hazards regression analyses showed that the aggregate presence of a chromosome breakpoint in any of 21 nonrandomly involved regions and breaks in 9 distinct regions (1p1, 1q2, 1p3, 3p1, 6p2, 11p1, 11q1, 12q2, and 13p1) were associated with reduced patient survival. Breakpoints in other areas of the genome, including other nonrandomly involved regions, were not associated with decreased survival. Because many cases had breakpoints in more than one nonrandomly involved region, proportional hazards regression was also used to analyze for effects of each nonrandomly involved region, controlling for effects of other regions. With this approach, only breakpoints within 1p1 and 3p1 retained independent, deleterious effects on survival. Similarly, when nonrandomly involved regions were entered into a proportional hazards model containing clinical variables associated with altered patient survival (tumor grade, tumor stage, and residual disease > 1 cm after resection), only 1p1 (P = 0.007) and 3p1 (P = 0.04) were associated with independent, negative effects on survival. These studies demonstrate that chromosome breakpoints within specific, nonrandomly involved chromosome regions are associated with impaired survival in ovarian cancers. Regions 1p1 and 3p1 are identified as areas of particular significance and are appropriate targets for analytical techniques such as SAGE and microarray analysis.

Enrichment of the more hydrophilic bile acid ursodeoxycholic acid in the fecal water-soluble fraction after feeding to rats with colon polyps

We recently showed that feeding the cytoprotective bile acid ursodeoxycholic acid (UDCA) to rats resulted in significant reduction in polyps and especially cancers, both in number and size (D. L. Earnest et al., Cancer Res., 54: 5071-5074, 1994). Because fecal secondary bile acids [particularly deoxycholic acid (DCA)] are considered to promote formation of colon adenomas and cancer, we have now attempted to find a relationship between polyp reduction and fecal secondary bile acids after feeding UDCA to these rats. We examined the fecal bile acids in rats with polyps and compared them with fecal bile acids in control rats and also determined the bile acid composition in fecal aqueous phase, which is in direct contact with the colon epithelium and may be physiologically more active. Treatment with azoxymethane did not significantly alter fecal bile acid composition in the rats. Cholic acid feeding resulted in greatly increased proportions of DCA (82% of total bile acids versus 18% in control rats). On the other hand, UDCA feeding significantly reduced the proportion of fecal DCA (2% in control rats fed UDCA and 3% in rats also treated with azoxymethane). In control rats, 96% of the bile acids were present in the water-insoluble fraction and 4% in the water-soluble fraction. The major insoluble bile acids included DCA and hyodeoxycholic acid (73% of total bile acids). In contrast, the muricholic acids were concentrated in the soluble fraction (37%). When 0.4% UDCA was added to the diet, lithocholic acid increased in the insoluble fraction (40 versus 1%), but the hydrophilic UDCA and muricholic acids were enriched in the water-soluble fraction (37 and 43%, respectively). Thus, the hydrophobic bile acids were distributed predominantly in the water-insoluble fraction, whereas the hydrophilic bile acids were distributed preferentially in the water-soluble fraction. These data suggest that UDCA may prevent colon tumors and polyps by countering the toxic effect of DCA and enhancing the possible cytoprotective effects of UDCA and muricholic acids in the water-soluble fraction in the feces of rat.

Capillary gas chromatographic analysis of serum bile acids as the n-butyl ester-trimethylsilyl ether derivatives

Gas chromatographic separations of n-butyl ester-trimethylsilyl ether derivatives of several common bile acids were compared with those of the corresponding methyl ester-trimethylsilyl ether derivatives on a CP-Sil-5 CB capillary column. Both types of derivatives were similarly resolved from each other. However, the n-butyl ester-trimethylsilyl ether derivatives of the bile acids showed longer retention times than the corresponding methyl ester-trimethylsilyl ethers and unlike the methyl ester-trimethylsilyl ether derivatives, were completely resolved from and eluted later than the trimethylsilyl ethers of common plasma sterols including sitosterol. A simplified method of plasma work-up for quantitation of bile acids and application of the above method in quantification of plasma bile acids in humans is described.

Inhibition of cyclobutane pyrimidine dimer formation in epidermal p53 gene of UV-irradiated mice by alpha-tocopherol

Mutations or alterations in the p53 gene have been observed in 50-100% of ultraviolet light (UV)-induced squamous cell carcinoma in humans and animals. Most of the mutations occurred at dipyrimidine sequences, suggesting that pyrimidine dimers in the p53 gene play a role in the pathogenesis of cutaneous squamous cell carcinoma. We previously showed that topical alpha-tocopherol prevents UV-induced skin carcinogenesis in the mouse. In the present study we asked whether topical alpha-tocopherol reduces the level of UV-induced cyclobutane pyrimidine dimers in the murine epidermal p53 gene. Mice received six dorsal applications of 25 mg each of alpha-tocopherol, on alternate days, before exposure to 500 J/m2 of UV-B irradiation. Mice were killed at selected times after irradiation. The level of dimers in the epidermal p53 gene was measured using the T4 endonuclease V assay with quantitative Southern hybridization. Topical alpha-tocopherol caused a 55% reduction in the formation of cyclobutane pyrimidine dimers in the epidermal p53 gene. The rate of reduction of pyrimidine dimers between 1 and 10 hours after irradiation was similar in UV-irradiated mice, regardless of alpha-tocopherol treatment. Therefore, the lower level of cyclobutane pyrimidine dimers in UV-irradiated mice treated with alpha-tocopherol than in control UV-irradiated mice resulted from the prevention of formation of the dimers, and not from enhanced repair of these lesions. Our results indicate that alpha-tocopherol acts as an effective sunscreen in vivo, preventing the formation of premutagenic DNA lesions in a gene known to be important in skin carcinogenesis.

Capillary gas-liquid chromatography of acetate-methyl esters of bile acids

Gas-liquid chromatographic separations of acetate-methyl esters of several common bile acids with and without a hydroxyl group at C-6 are compared with those of the corresponding trimethylsilyl ether-methyl esters on a CP-Sil-5 CB capillary column. Unlike the trimethylsilyl ether derivatives, the retention indices of the corresponding acetates were greatly influenced by the number of hydroxyl groups in the ring system. Epimeric hydroxyl groups at carbons 6, 7 as well as 12 increased retention index of the acetate-methyl esters of the bile acids, the effect of the 7 beta-hydroxyl group being most prominent. The 6 beta-acetoxyl group increased the retention index more than the 6 alpha-acetoxy group and contrary to the trimethylsilyl ether derivatives, a 6 beta, 7 beta-diacetoxy group showed larger increase in the retention index than the corresponding 6 alpha, 7 beta-diacetoxy group. The acetate derivatives of bile acid-methyl esters show larger retention times and reduced sensitivity than the corresponding trimethylsilyl ether derivatives. However, gas chromatography of bile acid acetate-methyl esters can be very useful for the characterization of bile acids and for bile acid analysis in the rat where muricholic acids and hyodeoxycholic acid are in abundance, since these bile acids are difficult to resolve from each other and from other common bile acids as the trimethylsilyl ether derivatives.

Structure-activity relationships of novel hematoregulatory peptides

Hematopoiesis is a lifelong cell renewal process regulated by a family of lineage specific hematopoietic growth factors. Several hematopoietic growth factors such as G-CSF, GM-CSF, and M-CSF have been clinically evaluated for enhancement of host defense in normal and immunocompromised patients and for the treatment of infectious diseases. This paper reports the structure-activity relationships of low molecular weight hematoregulatory peptides based on a nonapeptide (1, SK&F 107647). Like the macromolecular growth factors, these peptides modulate host defense. A molecular target for this class of compounds has not yet been identified. However, the structure-activity relationships established by this study implicate a very specific molecular recognition event that is pivotal for the biological activities of 1 and its analogues.

Adherence enhancers in pill-related clinical trials: a health behavior in cancer prevention model-based approach

Preventing non-adherence and treating adherence failure are important to consider in designing community-based clinical trials. The approach and methods for managing adherence are vital. This paper describes a practical and theoretically-based strategy for managing adherence in a small cancer prevention trial with subjects (n = 40) taking a non-steroidal anti-inflammatory drug, piroxicam. Average daily pill intake adherence was exceptionally high (97.4%) as measured by self-report calendar. Thus, the generalized adherence enhancement approach used in this study may have been a related factor, although statistical model-testing was not possible in this small trial. The generalized intervention took into account factors such as the potential barriers and benefits of being in the study, self-efficacy and satisfaction with the participant/staff relationship. These and other theoretical variables were incorporated into an overall adherence strategy that is discussed.

Design and recruitment for retinoid skin cancer prevention (SKICAP) trials. The Southwest Skin Cancer Prevention Study Group

The retinoid skin cancer prevention (SKICAP) trials are a set of double-blind, randomized, placebo-controlled clinical trials. The SKICAP-actinic keratoses (AK) trial tests the hypothesis that daily supplementation of retinol (25,000 IU) for 5 years reduces the incidence of skin cancers in high-risk individuals, those with a history of greater than ten clinically or pathologically diagnosed AK and, at most, one prior pathologically confirmed cutaneous squamous cell carcinoma (SCC) or basal cell carcinoma (BCC). The SKICAP-SCC/BCC (S/B) trial tests the hypothesis that daily supplementation of retinol (25,000 IU) or 13-cis-retinoic acid (5 or 10 mg) for 3 years reduces skin cancer incidence in very high-risk individuals, those with a history of at least four pathologically confirmed SCCs or BCCs. Between 1984 and 1988, 2800 participants were enrolled at two clinics on the SKICAP-AK trial; and between 1985 and 1990, a total of 719 participants were enrolled at four clinics on the SKICAP-S/B trial. The initial recruitment strategy was referral by dermatologists, but low accrual necessitated the use of other strategies to achieve enrollment goals, which included involving additional clinics and using paid trial-specific advertisements in print and electronic media. Thirteen % of the SKICAP-AK participants and 36% of the SKICAP-S/B participants were enrolled through dermatologist referral, whereas paid advertisements resulted in enrollment of 87% of SKICAP-AK and 43% of SKICAP-S/B participants. A population-based skin cancer registry was used to identify and enroll the remaining 21% of the SKICAP-S/B participants.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of proliferating cell nuclear antigen versus the more standard measures of rectal mucosal proliferation rates in subjects with a history of colorectal cancer and normal age-matched controls

Measurement of proliferation rates by the more standard in vitro uptake techniques of [3H]thymidine and 5'-bromo-2'-deoxyuridine (BrdUrd) labeling indices (LIs) were compared to proliferating cell nuclear antigen (PCNA) in rectal mucosal biopsies from 16 subjects with resected colorectal cancer and 14 normal age-matched controls. Correlation coefficients for BrdUrd versus PCNA, [3H]thymidine versus PCNA, and BrdUrd versus [3H]thymidine were 0.691, 0.876, and 0.770, respectively. No significant differences (P > 0.05) were detected in total mean LIs between the LI methods for the normal group. In contrast, total PCNA LIs were found to be significantly different in the resected cancer patients when compared to either BrdUrd (P = 0.005) or [3H]thymidine (P < 0.001). A significant difference (P = 0.010) in total PCNA LI but not in total [3H]thymidine or BrdUrd LIs was also observed between normal controls and resected colorectal cancer subjects. Compartmental analysis of the cancer group versus the normals showed a significant difference in compartments 1 and 3 for PCNA LIs only. The reproducibility of two PCNA LI counts was excellent (r = 0.9). In addition, the reliability of mean LIs were > 0.8 with the exception of [3H]thymidine in the normal group (0.7). These study results demonstrate that PCNA LIs in human rectal mucosal biopsies are correlated highly with other more commonly used cellular proliferation measurements; however, PCNA LIs were found to be significantly higher than the other two methods in the resected colorectal cancer subjects.

Hyperpigmentation and melanocytic hyperplasia in transgenic mice expressing the human T24 Ha-ras gene regulated by a mouse tyrosinase promoter

The tyrosinase promoter has been used to target expression of the mutated human T24 Ha-ras oncogene in pigment-producing cells of transgenic mice. Two independent founder mice carrying the transgene survived and showed the same distinct phenotype of mutated coat color, deeply pigmented skin with multiple nevi, and twirling behavior. The offspring of one of these founders were developed into a line that stably expressed the same phenotype. Histopathological analysis of the tissues revealed hyperpigmentation and/or melanocytic hyperplasia in the skin, eyes, inner ear, and meningeal membranes in the brain. Reverse transcriptase-polymerase chain reaction analysis revealed expression of the transgene in skin, brain, and spleen. We propose that these transgenic mice will be a model for studying the process of multistage melanoma carcinogenesis and a system for evaluating potential chemopreventive agents.

Clonal chromosome abnormalities in 54 cases of ovarian carcinoma

As a prelude to assessing the relationship of chromosome alterations to clinical outcome in ovarian carcinoma, we report on the cytogenetic analysis on short-term cultures from 54 patients. All patients had histopathologically confirmed malignancy, with the majority of cases demonstrating serous ovarian adenocarcinomas. Structural alterations were evident in 52 cases, whereas numeric changes were identified in 13 cases. The most notable numeric abnormalities were loss of the X-chromosome (9/13 total cases) and +7 (3/9 diploid cases). Structural alterations most frequently involved chromosomes 1, 3, 6, 7, 11, and 12. Chromosomal breakpoints were shown to cluster in several chromosomal banding regions, including 1p36, 1p11-q21, 3p23-p10, 7p (especially 7p22), 11p, 11q, 12p13-q12, and 12q24. The frequency of structural alterations involving the following chromosome arms was found to be significantly increased: 1p (p < 0.01), 7p (p < 0.01), 11p (p < 0.01), 11q (p < 0.05), and 12p (p < 0.05). An analysis of the net gain or loss of chromosome segments was also performed, with the most consistent tendency observed being over-representation of 1q and chromosome 7, deletion of 1p, and loss of the X chromosome.

Oral cancer prevention: the case for carotenoids and anti-oxidant nutrients

The most convincing evidence for a preventive role for any modality is obviously demonstration of incidence reduction produced by that modality. However, cancer prevention trials with cancer incidence as an endpoint have logistic problems rendering them essentially impossible to conduct for most malignancies. Hence a workable strategy often involves analysis of other, indirect lines of evidence to reach conclusions. For oral cancer, dietary epidemiologic evidence points to a protective role for foods rich in carotenoids. Other anti-oxidants, such as vitamin C, are also implicated. Similarly, laboratory evidence points to a carcinogenesis inhibitory role for both retinoids and carotenoids. Clinical studies have targeted premalignant lesions, i.e., oral leukoplakia. For over two decades the efficacy of retinoids, natural and synthetic, has been known. Nevertheless, it has been difficult to translate this into a recommendation for prevention because of the toxicity of retinoids. The synthetic retinoid most often used in these trials is 13-cis-retinoic acid. This compound is toxic even at very low doses (0.1 mg/kg/day), particularly when given over several weeks to months. Hence, although effective, it cannot be advocated for prevention or oral cavity cancer. Studies with nontoxic antioxidants, such as beta-carotene, are much more recent. Early results are promising in that beta-carotene, alone or in combination with other nutrients, can reverse oral leukoplakia without toxicity in short-term trials. Studies currently under way will demonstrate whether durable remissions can be obtained using this strategy. It should be emphasized that such long-term trials are problematic to conduct with the toxic retinoids because the risks of prolonged exposure to them outweighs the chance of cancer development in the usual leukoplakia lesion.

Evidence for persistence of mitoxantrone within the peritoneal cavity following intraperitoneal delivery

In clinical trials examining the intraperitoneal (ip) administration of mitoxantrone as therapy of platinum-refractory small-volume residual ovarian cancer, the characteristic "blue color" of the agent has been demonstrated to stain the surface of the peritoneal cavity and to persist for > or = 1 month following the last course of therapy. To determine if this blue staining material contains potentially cytotoxic concentrations of mitoxantrone, we analyzed tissue obtained at exploratory laparotomy in six women who had last received the agent administered ip from 6-22 weeks prior to surgery. Concentrations of mitoxantrone ranged from < 0.1 to 13.8 micrograms/g of tissue examined. Since any mitoxantrone present on the peritoneal surface will be highly protein bound, any residual drug may not have cytotoxic potential. The dose-response curves of mitoxantrone in a human clonogenic cytotoxicity assay against the RPMI 2780/S human ovarian cell line were virtually identical when the cells were incubated in either 5 or 50% fetal bovine serum, suggesting that protein binding will not significantly impair mitoxantrone-induced tumor cell killing. We conclude that the ip administration of mitoxantrone may lead to prolonged exposure of surface tumor to the high local concentrations of the active cytotoxic agent. This effect may contribute significantly to the antineoplastic potential of ip mitoxantrone in patients with small-volume residual ovarian cancer.

Design and analysis of studies to reduce the incidence of colon polyps

Decisions regarding the design and analysis of a phase III study to reduce the incidence of colorectal polyps must take into account two complicating factors: the possibility that polyps are missed during screening exams, and variable lengths of follow-up. In this paper we investigate the effects due to misclassification on the power of statistical tests to detect a change in polyp recurrence rates. We also use Monte Carlo studies to examine the relative efficiency of different methods of adjusting for variable times of follow-up.

SWOG 8825: melphalan GM-CSF: a phase I study

The use of intravenous melphalan at higher doses is limited by severe myelosuppression. It was postulated that GM-CSF would permit the use of higher dose melphalan with only moderate myelosuppression easily manageable in an outpatient setting. Therefore, a phase I study of intravenous melphalan utilizing GM-CSF (recombinant granulocyte-macrophage colony-stimulating factor) support was initiated. Intravenous melphalan at doses of 15-45 mg/m2 was administered every 28 days. GM-CSF was utilized at doses of 10-20 micrograms/kg/day subcutaneously Days 2-21 on a 28-day cycle. Twenty-five patients received 53 courses of therapy. The dose-limiting toxicities were severe or life-threatening granulocytopenia and thrombocytopenia. Utilizing 20 micrograms/kg/day GM-CSF, the maximum tolerated dose (MTD) of melphalan is 30 mg/m2 and, with 10 mg/kg/day GM-CSF, the maximum tolerated melphalan dose is only 20 mg/m2. One patient with ovarian cancer achieved a partial response. Because the reported MTD of intravenous melphalan without GM-CSF is 30 mg/m2, GM-CSF has not allowed sufficient escalation of the intravenous melphalan dose for routine outpatient use.

A community-based feasibility study using wheat bran fiber supplementation to lower colon cancer risk

METHODS

In this feasibility study, free-living older adults (n = 180; means = 67.5 years old) were randomly assigned to one of three levels of a 3-month standardized compliance enhancement program.

RESULTS

Regarding subject compliance with the 18 g/day wheat bran fiber supplement, the high compliance enhancement group had a superior regimen compliance rate (88%) versus the medium and low groups, (66 and 29%, respectively) (P = 0.01), with similar attrition rates.

CONCLUSION

No significant gastrointestinal side effects and changes in body weight were reported. For similar efficacy, the comprehensive compliance enhancement group had the greatest cost effectiveness.

An endogenous digitalis-factor derived from the adrenal gland: studies of adrenocortical tumor cells

The present studies demonstrate that the murine adrenocortical tumor cell line Y-1 releases a digoxin-like immunoreactive material into both serum-supplemented nutrient medium and minimal Krebs-Ringer bicarbonate medium. Release of pregnenolone into minimal medium from these cells was consistently inhibited by addition of the cholesterol side-chain cleavage inhibitor aminoglutethimide. However, release of digoxin-like immunoreactivity (DLI) was not similarly affected. To exclude the possibility that DLI could be accounted for by cross-reaction with another known adrenal steroid, aminoglutethimide inhibition was accompanied by inhibition of 17 alpha-hydroxylase with SU-10603 and inhibition of 3 beta-hydroxysteroid dehydrogenase with cyanoketone. Once again, pregnenolone release was effectively inhibited, but no similar pattern of inhibition of DLI release was observed. Increasing the time of the incubation periods from 1 to 2 h did not change the pattern of secretion of pregnenolone or DLI. HPLC analysis of DLI released over prolonged culture periods into serum-supplemented nutrient medium showed high levels of DLI in a single major and several adjacent peaks. Analysis of the ability of extracts of Y-1-conditioned medium to compete with tritiated ouabain for binding to erythrocytes indicates that conditioned medium contained highly enriched levels of ouabain-like activity. On HPLC analysis, the distribution of this activity showed partial correlation with the distribution of DLI. These observations indicate that Y-1 cells produce and release significant quantities of a material with cardiac glycoside-like properties reflected in the cross-reactivity with antidigoxin antibodies and the ability to compete with ouabain for binding to erythrocytes. In substantiation of previous findings in chopped adrenal cultures, the cardiac glycoside-like activity does not appear to result from cholesterol side-chain cleavage or pregnenolone production, since inhibition of side-chain cleavage as well as subsequent 17 alpha-hydroxylation and 3 beta-dehydrogenation did not result in consistent inhibition of DLI release.