Ian C. Summerhayes

The DCC protein and prognosis in colorectal cancer

BACKGROUND Allelic loss of chromosome 18q predicts a poor outcome in patients with stage II colorectal cancer. Although the specific gene inactivated by this allelic loss has not been elucidated, the DCC (deleted in colorectal cancer) gene is a candidate. We investigated whether the expression of the DCC protein in tumor cells is a prognostic marker in colorectal carcinoma. METHODS The expression of DCC was evaluated immunohistochemically in 132 paraffin-embedded samples from patients with curatively resected stage II and III colorectal carcinomas. The Cox proportional-hazards model was used to adjust for covariates including age, sex, tumor site, degree of tumor differentiation, and use of adjuvant therapy. RESULTS The expression of DCC was a strong positive predictive factor for survival in both stage II and stage III colorectal carcinomas. In patients with stage II disease whose tumors expressed DCC, the five-year survival rate was 94.3 percent, whereas in patients with DCC-negative tumors, the survival rate was 61.6 percent (P<0.001). In patients with stage III disease, the respective survival rates were 59.3 percent and 33.2 percent (P=0.03). CONCLUSIONS DCC is a prognostic marker in patients with stage II or stage III colorectal cancer. In stage II colorectal carcinomas, the absence of DCC identifies a subgroup of patients with lesions that behave like stage III cancers. These findings may thus have therapeutic implications in this group of patients.

Incomplete Renal Tumor Destruction Using Radio Frequency Interstitial Ablation

PURPOSE We evaluate the efficacy of temperature based radio frequency ablation as a potential treatment modality for small (less than 3.5 cm.) renal tumors. MATERIALS AND METHODS We treated 15 patients with a total of 20 tumors with radio frequency ablation through an open surgical approach immediately before partial nephrectomy. All tumors were biopsied before radio frequency ablation treatment. Tumors were heated to 90 to 110C for 6 to 16 minutes (mean 9.1). Tumor ablation was monitored by direct vision and ultrasound. Partial nephrectomy was performed in standard fashion. All specimens were stained with hematoxylin and eosin, and 5 specimens were stained for nicotinamide adenine dinucleotide (NADH) diaphorase activity. RESULTS Tumors ranged from 1.5 to 3.5 cm. (mean 2.4) in greatest dimension. All 20 specimens had evidence of morphologically unchanged tumor and normal renal parenchyma on standard hematoxylin and eosin staining. Of the 5 specimens 4 stained positively for NADH in areas confirmed to be tumor in hematoxylin and eosin stained neighboring sections. There was 1 intraoperative renal pelvic thermal injury requiring pyeloplasty and 2 postoperative caliceal leaks requiring stent placement. CONCLUSIONS In our series radio frequency therapy did not result in total tumor destruction when specimens were examined with hematoxylin and eosin or NADH staining. We believe that radio frequency interstitial tumor ablation of renal cell carcinoma without subsequent tissue resection should continue to be an investigational treatment modality for those who would otherwise undergo partial or radical nephrectomy.

Suppression of Wnt Signaling by the Green Tea Compound (–)-Epigallocatechin 3-Gallate (EGCG) in Invasive Breast Cancer Cells REQUIREMENT OF THE TRANSCRIPTIONAL REPRESSOR HBP1

Genetic and biochemical de-regulation of Wnt signaling is correlated with breast and other cancers. Our goal was to identify compounds that block Wnt signaling as a first step toward investigating new strategies for suppression of invasive and other breast cancers. In a limited phytonutrient screen, EGCG ((–)-epigallocatechin 3-gallate), the major phytochemical in green tea, emerged as an intriguing candidate. Epidemiological studies have associated green tea consumption with reduced recurrence of invasive and other breast cancers. Wnt signaling was inhibited by EGCG in a dose-dependent manner in breast cancer cells. The apparent mechanism targeted the HBP1 transcriptional repressor, which we had previously characterized as a suppressor of Wnt signaling. EGCG treatment induced HBP1 transcriptional repressor levels through an increase in HBP1 mRNA stability, but not transcriptional initiation. To test functionality, DNA-based short hairpin RNA (shRNA) was used to knockdown the endogenous HBP1 gene. Consistently, the HBP1 knockdown lines had reduced sensitivity to EGCG in the suppression of Wnt signaling and of a target gene (c-MYC). Because our ongoing studies clinically link abrogation of HBP1 with invasive breast cancer, we tested if EGCG also regulated biological functions associated with de-regulated Wnt signaling and with invasive breast cancer. EGCG reduced both breast cancer cell tumorigenic proliferation and invasiveness in an HBP1-dependent manner. Together, the emerging mechanism is that EGCG blocks Wnt signaling by inducing the HBP1 transcriptional repressor and inhibits aspects of invasive breast cancer. These studies provide a framework for considering future studies in breast cancer treatment and prevention.

Identification and Prognostic Significance of an Epithelial-Mesenchymal Transition Expression Profile in Human Bladder Tumors

Purpose: Epithelial to mesenchymal transition (EMT) is reportedly an important transition in cancer progression in which the underlying cellular changes have been identified mainly using in vitro models. In this study, we examined the expression pattern of EMT markers in vivo and determined the occurrence and clinical significance of these events in a series of bladder carcinomas. Experimental Design: Eight hundred and twenty-five tumor samples from 572 bladder cancer patients were assembled in 10 tissue microarrays. Paraffin sections from each tissue microarray were subjected to antigen retrieval and processed by immunohistochemistry for the expression of E-cadherin, plakoglobin, β-catenin, N-cadherin, and vimentin. Results: Pathologic expression of E-cadherin, β-catenin, plakoglobin, and vimentin were associated with the clinicopathologic variables of grade and stage with only the cytoplasmic localization of plakoglobin found associated with lymph node status. Associations between the aforementioned markers were found significant as determined by the Spearman correlation coefficient with N-cadherin showing no associations in this analysis. In univariate survival analysis involving patients who underwent cystectomy, the reduction or loss of plakoglobin significantly influenced overall survival (P = 0.02) in which the median time to death was 2 years compared with 4 years when a normal level of plakoglobin was recorded. When the analysis was done for cancer-specific survival, low levels of both plakoglobin (P = 0.02) and β-catenin (P = 0.02) significantly influenced survival. Conclusion: The putative markers of EMT defined within a panel of bladder carcinoma cell lines were recorded in vivo, frequently associated with tumors of high grade and stage. Although multivariate analysis showed no significant influence of the EMT biomarkers on survival, alterations associated with plakoglobin were identified as significant prognostic features in these tumors.

DNA Integrity as a Potential Marker for Stool-based Detection of Colorectal Cancer

BACKGROUND Molecular genetic analysis of DNA in patient stools has been proposed for screening of colorectal cancer (CRC). Because nonapoptotic cells shed from tumors may contain DNA that is less degraded than DNA fragments from healthy colonic mucosa, our aim was to show that DNA fragments isolated from stools of patients with CRC had higher integrity than DNA isolated from stools of patients with healthy colonic mucosa. METHODS We purified DNA from the stools of a colonoscopy-negative control group and patients with CRC and examined the relationship between long DNA fragments and clinical status by determining stool DNA integrity, using oligonucleotide-based hybrid captures with specific target sequences in increasingly long PCR reactions (200 bp, 400 bp, 800 bp, 1.3 kb, 1.8 kb, 24 kb). DNA fragments obtained from CRC patients were compared with fragments obtained from colonoscopy-negative individuals for length and/or integrity. RESULTS DNA fragments isolated from CRC patients were of higher molecular weight (>18 bands detected of a total of 24 possible bands) than fragments isolated from fecal DNA of the colonoscopy-negative control group. CONCLUSIONS The presence of long DNA fragments in stool is associated with CRC and may be related to disease-associated differences in the regulation of proliferation and apoptosis. An assay of fecal DNA integrity may be a useful biomarker for the detection of CRC.

CLINICAL AND PATHOLOGICAL CHARACTERISTICS OF MICROPAPILLARY TRANSITIONAL CELL CARCINOMA: A HIGHLY AGGRESSIVE VARIANT

PURPOSE We present preliminary clinical, histochemical and molecular findings for 5 patients with micropapillary transitional cell carcinoma of the bladder, a rare histological variant not widely recognized in the urological literature. MATERIALS AND METHODS The 5 patients were prospectively identified. In 3 cases immunohistochemical staining for expression of CD31, p53, E-cadherin, and alpha, beta and gamma-catenin was performed on paraffin embedded tissue. Sequencing was used to identify point mutations in exons 5 to 9 of p53, and exons 1 and 2 of H-ras. RESULTS Of the patients 2 died within 1 year of presentation to our institution with rapid local extension along the bladder serosal surface and ureteral sheaths. Another patient had progression to invasive disease within 22 months. In the 3 cases with immunohistochemical staining p53 was negative, despite positive staining of nonmicropapillary transitional cell carcinoma within the same specimen. Stains for the angiotrophic marker CD31 were negative. In all 3 cases normal membrane associated alpha, beta and gamma-catenin expression was present. Examination of p53 sequences revealed a single point mutation in exon 8 of 1 case. In 2 cases different mutations in exon 1 of H-ras were noted. CONCLUSIONS Micropapillary transitional cell carcinoma is a rare and highly aggressive variant. Paradoxically, our study demonstrated no significant p53 abnormalities. The lacunar histological pattern did not appear to represent invasion of vascular spaces. Rather, these tumors seemed to have the ability to disrupt and replace the normal stromal matrix to achieve rapid nonendothelial extension. Thus, micropapillary histology may predict a lesser likelihood of surgical cure.

Influence of glial growth factor and Schwann cells in a bioresorbable guidance channel on peripheral nerve regeneration.

Using an established rat peripheral nerve regeneration model, we investigated the role of glial growth factor (GGF) in nerve regeneration in combination with a novel bioresorbable poly(lactic-co-glycolic) acid (PLGA) guide in vivo. Schwann cells, established from a 1-cm segment of excised rat sciatic nerve, were isolated and seeded onto nerve guides with or without GGF (n = 24/group). Living nerve guides were re-established in these animals, and nerve regeneration was assessed over a period of 12 weeks. Histological studies revealed a reduction in the total axon count and the number of myelinated axons in the presence of exogenously added Schwann cells compared to saline controls. In contrast, the addition of GGF alone enhanced the total number of axons and significantly increased the number of blood vessels. Although combining GGF with Schwann cells negated the enhanced numbers of axons and blood vessels seen with GGF alone, this combination resulted in the highest myelination index and the fastest conduction velocities recorded. The PLGA guide material did not trigger any histologically detectable host response and was permissive for nerve regeneration in this animal model. The results from this study demonstrate the potential utility of this guide in vivo and establish a promotional role for GGF in nerve regeneration.

A microRNA expression ratio defining the invasive phenotype in bladder tumors

OBJECTIVE The goal of this study was to identify a microRNA (miRNA) signature in bladder cancer capable of differentiating superficial from invasive disease. METHODS Expression profiling of 343 miRNAs was performed in a microarray format using noninvasive and invasive bladder carcinoma cell lines with differential expression confirmed using a single molecule detection platform assay. miR-21 and miR-205 expression levels were determined in 53 bladder tumors (28 superficial and 25 invasive). Sensitivity, specificity, and a ROC curve were calculated to determine the discriminatory power of the miRNA ratio to predict invasion. Knockdown and forced expression of miRNAs was performed to evaluate their role in invasion. RESULTS Expression profiling of 343 miRNAs, using noninvasive and invasive bladder cell lines, revealed significant differential expression of 9 miRNAs. Cell lines characterized as invasive showed a miR-21:miR-205 ratio at least 10-fold higher than the quantitative ratio obtained from non-invasive cell lines. The same expression ratio was determined in 53 bladder tumors. From these results, we recorded a sensitivity and specificity of 100% and 78%, respectively, using a cutoff of 1.79 to predict an invasive lesion. The area under the receiver operator characteristic curve was 0.89. Using in vitro invasion assays, we have demonstrated a role for miR-21 in establishing the invasive phenotype of bladder carcinoma cells. CONCLUSION In this study, we identified a miR-21:miR-205 expression ratio that has the ability to distinguish between invasive and noninvasive bladder tumors with high sensitivity and specificity, with the potential to identify superficial lesions at high risk to progress.

Decreased Uptake and Retention of Rhodamine 123 by Mitochondria in Feline Sarcoma Virus-Transformed Mink Cells

A reduce uptake and retention of the mitochondria-specific membrane potential probe rhodamine 123 by feline sarcoma virus (FeSV)-transformed mink fibroblasts (64F3) has been detected. The decreased accumulation of rhodamine 123 by 64F3 mitochondria is not due to abnormal plasma membrane dye permeability, since after microinjection of the dye these cells are still unable to retain the dye at levels comparable to the untransformed parental cells, CCL 64. Nigericin, an ionophore that mediates an electrically neutral exchange of protons for potassium ions resulting the elimination of the pH gradient across the mitochondrial membrane and a compensatory increase in mitochondrial membrane potential with continued respiration, increases both the dye uptake and the retention time in transformed 64F3 cells. These results suggest that mitochondria in FeSV-transformed mink cells may have an abnormally low mitochondrial membrane potential accompanied by a relatively high pH gradient. Since anioic metabolites such as pyruvate and glutamate are accumulated by mitochondria in proportion to the delta pH across the mitochondrial membrane, the abnormal mitochondria described here may contribute to the abnormal metabolic state of FeSV-transformed cells.

A MicroRNA expression profile defining the invasive bladder tumor phenotype

OBJECTIVE The purpose of this study was to identify microRNA (miRNA) involved in the transition between the noninvasive and invasive urothelial carcinoma of the bladder (UCB) phenotype. METHODS Differential expression of miRNA was identified in a microarray format between noninvasive and invasive UCB cell lines and confirmed using quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) within this cell panel. Normalization of qRT-PCR with miR-222 was established from the microarray data and validated within a panel of 57 UCB tumors (26 noninvasive lesions (Ta/G1) and 31 invasive lesions (T2-T4). Pre-miR constructs were transfected into appropriate UCB cell lines to establish a change in invasive potential. RESULTS Differential expression of miRNAs was identified from microarray analysis and included reduced expression associated with miR-30b, miR-31, miR-141, miR-200a, miR-200b, miR-200c, miR-205, miR-21 in invasive lesions and elevated miR-99a in noninvasive UCB lesions. Reduced invasion potential was recorded in UM-UC-3, following pre-miR transfection, in all UCB cell lines with the exception of UM-UC-3/miR-30b transfectants. Our results identify a panel of miRNA modulated and expressed in invasive UCB tumors and demonstrates a role for them in the invasive phenotype. CONCLUSIONS The diagnostic test, based on the three most discriminatory miRNAs in our panel (miR-200c, miR-141, and miR-30b), showed a sensitivity of 100% and a specificity of 96.2%. Such a panel of miRNAs has the potential to identify invasive bladder tumors misclassified in pathologic assessment of bladder biopsy specimens.