Linda B. Mora

Stat3 regulates genes common to both wound healing and cancer

Wound healing and cancer are both characterized by cell proliferation, remodeling of extracellular matrix, cell invasion and migration, new blood vessel formation, and modulation of blood coagulation. The mechanisms that link wound healing and cancer are poorly understood. We report here that Stat3, a common signaling mechanism involved in oncogenesis and tissue injury, regulates a common set of genes involved in wound healing and cancer. Using oligonucleotide gene arrays and quantitative real-time PCR, we evaluated changes in global gene expression resulting from expression of Stat3 in lung epithelial cells. We report here previously uncharacterized genes induced by Stat3 implicated in signaling pathways common to both wound healing and cancer including cell invasion and migration, angiogenesis, modulation of coagulation, and repression of interferon-inducible genes. Consistent with these results, we found increased Stat3 activity associated with wound healing in chronically inflamed mouse lungs and increased Stat3 activity was identified at the leading edge of lung tumors invading adjacent nontumor stroma. These findings provide a molecular basis for understanding cancer as a deregulation of normal wound healing processes.

Expression of insulin-like growth factor-1 receptor in human colorectal cancer

The activation of the insulinlike growth factor 1/IGF-1 receptor system (IGF1/IGF1-R) has recently emerged as critical event in transformation and tumorigenicity of several murine and human tumors. Expression of IGF1 and of IGF1-R has been demonstrated in normal and neoplastic intestinal cell lines of rats and humans. However, the modulation of IGF1-R expression during the progression from normal colonic mucosa to adenoma, to carcinoma, and to metastasis, has not been evaluated. In this retrospective study, we investigated the expression of IGF1-R in 12 colonic adenomas (AD), 36 primary colorectal adenocarcinomas (CA), and in 27 corresponding metastases (MT). Normal colonic mucosa (N) was adjacent to the CA in 34 cases. Formalin-fixed, paraffin-embedded tissues of each case were immunostained using the avidin-biotin-peroxidase method. We used an anti-IGF1-R rabbit polyclonal antibody (Santa Cruz Biotechnology, CA; dilution 1:100). Positive staining was quantitated by CAS-200. Moderate to strong cytoplasmic immunostaining was observed in 34 of 36 CA (96%), and in 25 of 27 MT (93%). In all of the positive MTs, the intensity of the staining was always strong. In 10 of 12 ADs (83%), only a faint cytoplasmic stain was identified. Normal mucosa when present was negative. Strong IGF1-R positivity correlated with higher grade and higher-stage tumors (P < .01). These data suggest a role of IGF1-R expression during the progression of colorectal adenoma to carcinoma. An increased number of IGF1-R receptors may favor the metastasis of colorectal cancer.

PLATINUM COMPOUNDS THAT INHIBIT CONSTITUTIVE STAT3 SIGNALING AND INDUCE CELL CYCLE ARREST AND APOPTOSIS OF MALIGNANT CELLS

Previous studies have established constitutive activation of Stat3 protein as one of the molecular changes required for tumorigenesis. To develop novel therapeutics for tumors harboring constitutively active Stat3, compounds from the NCI 2000 diversity set were evaluated for inhibition of Stat3 DNA-binding activity in vitro. Of these, a novel platinum (IV) compound, IS3 295, interacted with Stat3 and inhibited its binding to specific DNA-response elements. Further analysis suggested noncompetitive-type kinetics for the inhibition of Stat3 binding to DNA. In human and mouse tumor cell lines with constitutively active Stat3, IS3 295 selectively attenuated Stat3 signaling, thereby inducing cell growth arrest at G0/G1 phase and apoptosis. Moreover, in transformed cells, IS3 295 repressed expression of cyclin D1 and bcl-xL, two of the known Stat3-regulated genes that are overexpressed in malignant cells, suggesting that IS3 295 mediates anti-tumor cell activity in part by blocking Stat3-mediated sub-version of cell growth and apoptotic signals. Together, our findings provide evidence for the inhibition of Stat3 activity and biological functions by IS3 295 through interaction with Stat3 protein. This study represents a significant advance in small molecule-based approaches to target Stat3 and suggests potential new applications for platinum (IV) complexes as modulators of the Stat3 pathway for cancer therapy.

Inhibition of Bcr-Abl kinase activity by PD180970 blocks constitutive activation of Stat5 and growth of CML cells

Chronic myelogenous leukemia (CML) is a myeloproliferative disease characterized by the BCR–ABL genetic translocation and constitutive activation of the Abl tyrosine kinase. Among members of the Signal Transducers and Activators of Transcription (STAT) family of transcription factors, Stat5 is activated by the Bcr–Abl kinase and is implicated in the pathogenesis of CML. We recently identified PD180970 as a new and highly potent inhibitor of Bcr–Abl kinase. In this study, we show that blocking Bcr–Abl kinase activity using PD180970 in the human K562 CML cell line resulted in inhibition of Stat5 DNA-binding activity with an IC50 of 5 nM. Furthermore, abrogation of Abl kinase-mediated Stat5 activation suppressed cell proliferation and induced apoptosis in K562 cells, but not in the Bcr–Abl-negative myeloid cell lines, HEL 92.1.7 and HL-60. Dominant-negative Stat5 protein expressed from a vaccinia virus vector also induced apoptosis of K562 cells, consistent with earlier studies that demonstrated an essential role of Stat5 signaling in growth and survival of CML cells. RNA and protein analyses revealed several candidate target genes of Stat5, including Bcl-x, Mcl-1, c-Myc and cyclin D2, which were down-regulated after treatment with PD180970. In addition, PD180970 inhibited Stat5 DNA-binding activity in cultured primary leukemic cells derived from CML patients. To detect activated Stat5 in CML patient specimens, we developed an immunocytochemical assay that can be used as a molecular end-point assay to monitor inhibition of Bcr–Abl signaling. Moreover, PD180970 blocked Stat5 signaling and induced apoptosis of STI-571 (Gleevec, Imatinib)-resistant Bcr–Abl-positive cells. Together, these results suggest that the mechanism of action of PD180970 involves inhibition of Bcr–Abl-mediated Stat5 signaling and provide further evidence that compounds in this structural class may represent potential therapeutic agents for CML.

Significance of Fas and retinoblastoma protein expression during the progression of Barrett's metaplasia to adenocarcinoma.

Background: Barrett’s esophagus (BE) is a premalignant lesion characterized by replacement of normal squamous epithelium with columnar epithelium. This lesion can progress to dysplasia and adenocarcinoma. Recently, the Fas receptor and retinoblastoma (Rb) protein have been described as important mediators of apoptosis and tumor suppression, respectively. This study was undertaken to examine their expression during the progression of metaplasia to adenocarcinoma in BE.Methods: In a review of 56 adenocarcinomas arising in BE, the specimen blocks were examined using the immunohistochemical avidin-biotin-peroxidase complex technique. For each specimen, areas of normal epithelium were compared with areas of metaplasia, dysplasia, or carcinoma (when present). Monoclonal mouse anti-human antibodies were used to identify Rb protein (Rb-Ab5, 1/50 dilution; Oncogene Science) and the 40–50-kDa cell membrane Fas protein (APO-1/Fas, 1/5 dilution; DAKO Corp.).Results: Loss of Rb staining was observed as the metaplasia progressed to dysplasia and carcinoma, indicating accumulation of unstainable aberrant protein. Conversely, Fas protein staining was undetectable or weak in normal or metaplastic epithelium, increasing in the areas of high-grade dysplasia and carcinoma. These differences were statistically significant (P < .001).Conclusions: The accumulation of abnormal Rb protein during the progression of Barrett’s metaplasia to carcinoma leads to unsuppressed tumor growth. Fas overexpression may represent a cellular attempt to balance the uncontrolled tumor proliferation by promoting apoptosis.

Deregulated expression of LRBA facilitates cancer cell growth.

LRBA expression is induced by mitogens in lymphoid and myeloid cells. The Drosophila LRBA orthologue rugose/DAKAP550 is involved in Notch, Ras and EGFR pathways. These findings suggest that LRBA could play a role in cell types that have increased proliferative and survival capacity. Here, we show by microarray and real-time PCR analyses that LRBA is overexpressed in several different cancers relative to their normal tissue controls. We also show that LRBA promoter activity and endogenous LRBA mRNA levels are reduced by p53 and increased by E2F1, indicating that mutations in the tumor suppressors p53 and Rb could contribute to the deregulation of LRBA. Furthermore, inhibition of LRBA expression by RNA interference, or inhibition of its function by a dominant-negative mutant, leads to significant growth inhibition of cancer cells, demonstrating that deregulated expression of LRBA contributes to the altered growth properties of a cancer cell. Finally, we show that the phosphorylation of EGFR is affected by the dominant-negative mutant, suggesting LRBA plays a role in the mammalian EGFR pathway. These findings demonstrate that LRBA facilitates cancer cell growth and thus LRBA may represent a novel molecular target for cancer therapy.

Ancillary Techniques in the Followup of Transitional Cell Carcinoma: A Comparison of Cytology, Histology and Deoxyribonucleic Acid Image Analysis Cytometry in 91 Patients

PURPOSE Voided urine and bladder washing cytology are used frequently in the evaluation of transitional cell carcinoma of the bladder. As part of an ongoing investigation we report on the role of deoxyribonucleic acid (DNA) image analysis cytometry as an adjunct to cytology in the followup of patients with transitional cell carcinoma. MATERIALS AND METHODS Urine cytology and image analysis cytometry were performed independently on aliquots of voided urine, catheterized urine or bladder washings from 91 patients with previous or active transitional cell carcinoma of the bladder, and the results were compared to those of concurrent biopsy and clinical followup. RESULTS Of 75 recurrent transitional cell carcinomas 42 were detected by cytology, while 63 and 64 were identified by image analysis cytometry and biopsy, respectively, for a sensitivity of 57, 84 and 85%, respectively. Combined cytology and image analysis cytometry detected 67 recurrences, for an overall sensitivity of 89%. Of 11 cases undetected by concurrent biopsy 9 had abnormal DNA histograms with transitional cell carcinoma at followup and 2 were DNA diploid but with grade 1 transitional cell carcinoma at followup. Of 12 cases undetected by image analysis cytometry 8 were grade 1 and 4 were grade 2 transitional cell carcinoma. CONCLUSIONS Urine cytology and image analysis cytometry detect most recurrent tumors. Their combined use is indicated in the followup of patients with bladder transitional cell carcinoma.

CYCLIN D1 EXPRESSION AS A PROGNOSTIC PARAMETER IN PAPILLARY CARCINOMA OF THE THYROID

Papillary carcinoma of the thyroid is the most common thyroid cancer. At the time of clinical presentation, most papillary carcinomas are still confined to the thyroid gland, and appropriate surgical treatment achieves a 95% 5-year survival rate. Certain carcinomas, however, behave in a much more aggressive fashion. Because specific therapies do not exist, for those tumors that have escaped local control, patients with disseminated disease have little or no chance of permanent cure or long-term survival. Cyclin D1, a protein that plays a critical role in the control of the cell cycle, has been shown to be overexpressed in a variety of human neo-plasias and may serve as a prognostic parameter of disease progression. To explore the role played by cyclin D1 in the pathogenesis of thyroid papillary carcinoma, we have quantitated, by computerized image analysis, the immunohistochemical expression of cyclin D1 in formalin-fixed, paraffin-embedded tissue from 35 conventional papillary carcinomas of the thyroid and correlated the results with established clinicopathologic parameters and available survival data.

The Mainz Classification of Renal Cell Tumors.

BACKGROUND: Tumors arising from the renal tubular epithelium have variable characteristics and have been subject to a variety of histologic classifications. METHODS: The authors describe the distinct clinical, pathologic, phenotypic, and genotypic features of different types of renal tumors. RESULTS: The Mainz classification is now widely accepted because characteristic genetic alterations have been demonstrated in each tumor type. CONCLUSIONS: The increasing emphasis on utilizing genetic characteristics of specific tumors is reflected by the more widespread use of the Mainz classification for renal cell tumors.

Predictability of PSA failure in prostate cancer by computerized cytometric assessment of tumoral cell proliferation

OBJECTIVES To evaluate the relationship of DNA ploidy and cell proliferation (CP) with Gleason score (GS) and clinical outcome in prostate cancer. METHODS Sixteen patients with benign prostatic hyperplasia (BPH) and 65 patients with prostate cancer classified by GS (four groups: 2 to 4, 5 to 6, 7, and 8 to 10) were studied. All patients with carcinoma underwent prostatectomy and were separated into prostate-specific antigen (PSA) failure and nonfailure groups (failure if PSA 0.1 ng/mL or more three times after surgery). Tumoral CP (Ki-67 inmunostaining and SG2M phase) and DNA ploidy were evaluated by computerized cytometry. RESULTS BPH were diploid with low CP (8% SG2M cells or less). Carcinomas were either diploid with high CP (greater than 8% SG2M cells) or aneuploid. CP was significantly higher (P <0.001) in tumors with GS 7 or greater than in tumors with GS less than 7 (mean percent Ki-67 cells 18.3% versus 7.8%, respectively). PSA failure increased with GS (7.1% in GS 2 to 4, 21% in GS 5 to 6, 28.6% in GS 7, and 50% in GS 8 to 10), as well as with aneuploidy (18.5% in diploid tumors versus 72.7% in aneuploid tumors). Those experiencing PSA failure had significantly higher (P <0.001) CP than those not failing (mean percent Ki-67 cells 24% and mean percent SG2M 30.4% versus 8.7% and 13.5%, respectively). Cox regression analysis showed GS, DNA ploidy, Ki-67, and SG2M to each be univariately prognostic for time to PSA failure; however, Ki-67 and SG2M were more highly significant (P <0.0001 for both) than GS (P = 0.007) or DNA ploidy (P = 0.002). After adjusting for either SG2M or Ki-67 measures of CP, neither ploidy nor GS contained additional prognostic value. CONCLUSIONS Tumor CP and DNA ploidy can be reliably determined in prostate cancer by computerized cytometry. On the basis of our preliminary results, CP correlates well with GS and predicts PSA failure better than DNA ploidy or GS.