Joseph A. Holden

Inverse Relationship between Microsatellite Instability and K-ras and p53 Gene Alterations in Colon Cancer

Some studies have shown an inverse relationship between microsatellite instability in colon cancer and mutations in p53 and K-ras, whereas others have not. We therefore evaluated these features in a population-based sample of 496 individuals with colon cancer. Microsatellite instability was determined by a panel of 10 tetranucleotide repeats, the Bethesda consensus panel of mono- and dinucleotide repeats, and coding mononucleotide repeats in transforming growth factor-beta receptor type II, hMSH3, BAX, hMSH6, and insulin-like growth factor receptor type II. Mutations in codons 12 and 13 in K-ras were evaluated by sequencing. p53 overexpression (as detected by immunohistochemistry) was used as an indicator of p53 mutation; this was evaluated in 275 of the tumors. K-ras mutations were present in 33.2% of tumors, p53 overexpression in 51.5%, and microsatellite instability (as determined by the Bethesda consensus panel) in 12.5%. K-ras mutations were significantly less common in unstable tumors than stable tumors (11.8% versus 36.9%, P: < 0.001). p53 overexpression was significantly less common in unstable tumors than stable tumors (20.0% versus 55.7%, P: < 0.001). These inverse relationships between microsatellite instability and ras gene mutations and p53 overexpression were shown to be independent of tumor site in logistic regression analyses. All other measures of instability also showed statistically significant inverse relationships independent of tumor site with alterations in ras and p53, and instability results determined by the panel of 10 tetranucleotide repeats were highly significantly related to those determined by the Bethesda consensus panel. Coding mononucleotide repeat mutations were significantly more common in unstable tumors than stable tumors (85.7% versus 1.0%, P: < 0.001). We conclude that there is an inverse relationship between microsatellite instability and mutations in p53 and K-ras, and that the molecular profile of colon cancers with microsatellite instability is characterized by relatively infrequent mutations in K-ras and p53 and relatively frequent mutations in coding mononucleotide repeats.

Preservation of RNA for functional genomic studies: A multidisciplinary tumor bank protocol

Few human tumors are collected such that RNA is preserved for molecular analysis. Completion of the Human Genome Project will soon result in the identification of more than 100,000 new genes. Consequently, increasing attention is being diverted to identifying the function of these newly described genes. Here we describe a multidisciplinary tumor bank procurement protocol that preserves both the integrity of tissue for pathologic diagnosis, and the RNA for molecular analyses. Freshly excised normal skin was obtained from five patients undergoing wound reconstruction following Mohs micrographic surgery for cutaneous neoplasia. Tissues treated for 24 hours with RNAlater™ were compared histologically and immunohistochemically to tissues not treated with RNAlater. Immunohistochemical stains studied included: CD45, CEA, cytokeratin AE1/3, vimentin, S-100, and CD34 on formalin-fixed, paraffin embedded tissue and CD45 staining of frozen tissue. Slides were blinded and evaluated independently by three pathologists. The histologic and immunohistochemical parameters of tissue stored in RNAlater were indistinguishable from tissue processed in standard fashion with the exception of S-100 stain which failed to identify melanocytes or Langerhans cells within the epidermis in any of the RNAlater -treated tissues. Interestingly, nerve trunks within the dermis stained appropriately for S-100. Multiple non-cutaneous autopsy tissues were treated with RNAlater, formalin, liquid nitrogen (LN2), and TRIzol Reagent®. The pathologists were unable to distinguish between tissues treated with RNAlater, formalin, or frozen in LN2, but could easily distinguish tissues treated with TRIzol Reagent because of extensive cytolysis. RNA was isolated from a portion of the tissue treated with RNAlater and used for molecular studies including Northern blotting and microarray analysis. RNA was adequate for Northern blot analysis and mRNA purified from RNAlater -treated tissues consistently provided excellent templates for reverse transcription and subsequent microarray analysis. We conclude that tissues treated with RNAlater before routine processing are indistinguishable histologically and immunohistochemically from tissues processed in routine fashion and that the RNA isolated from these tissues is of high quality and can be used for molecular studies. Based on this study, we developed a multidisciplinary tumor bank procurement protocol in which fresh tissue from resection specimens are routinely stored in RNAlater at the time of preliminary dissection. Thus, precious human tissue can be utilized for functional genomic studies without compromising the tissues diagnostic and prognostic qualities.

Elevated cyclooxygenase-2 expression correlates with diminished survival in carcinoma of the cervix treated with radiotherapy

PURPOSE The purpose of this study was to examine the relationship between overall survival and prognostic factors in carcinoma of the cervix treated with radiation therapy. A clinicopathologic study was performed on 24 patients. METHODS AND MATERIALS Formalin-fixed, paraffin-embedded tumor biopsies were stained for Cyclooxygenase-2 (COX-2), Topoisomerase I, Topoisomerase II, and p53. Clinical factors such as stage, grade, tumor size, pre- and post-treatment hemoglobin level, and radiotherapy dose were also evaluated. RESULTS Median follow-up was 75 months for living patients. The only immunohistochemical or clinical factor that was associated with improved survival was decreased COX-2 distribution staining. High COX-2 distribution staining was associated with decreased overall survival (p = 0.021) and decreased disease-free survival (p = 0.015) by log-rank comparison of Kaplan-Meier survival curves. The 5-year overall survival rates for tumors with low vs. high COX-2 distribution values were 75% and 35%, respectively. COX-2 staining intensity was found to correlate positively with tumor size (p = 0.022). CONCLUSION These findings indicate that increased expression of COX-2 portends a diminished survival in patients with invasive carcinoma of the cervix treated with radiotherapy. Because COX-2 is an early-response gene involved in angiogenesis and inducible by different stimuli, these data may indicate opportunity to intervene with specific inhibitors of COX-2 in carcinoma of the cervix.

Human DNA topoisomerase II-alpha: A new marker of cell proliferation in invasive breast cancer

DNA topoisomerase II-alpha is the molecular target of doxorubicin, an active drug used in the therapy of breast cancer. From many in vitro studies, it is known that high levels of topo II-alpha expression correlate with drug sensitivity, and low levels of topo II-alpha correlate with drug resistance. In addition, the enzyme is known to be a marker of cell proliferation in normal tissues. Because the number of proliferating cells in a breast cancer has been shown to be prognostically important, and because doxorubicin is used in the treatment of breast cancer, we hypothesized that the measurement of topo II-alpha in breast cancer may not only give drug sensitivity information but also may yield important data on cell proliferation. In this study, formalin-fixed, paraffin-embedded tissue from 30 specimens of invasive breast cancer from 20 patients were immunohistochemically stained for topo II-alpha with a mouse monoclonal antibody. For each case, a topo II-alpha index was determined that represents the number of positive-staining tumor cells divided by the total number of tumor cells counted times 100. A similar index was determined for MIB1, a known cell proliferation marker. Each case was also graded according to the modified Bloom-Richardson criteria and evaluated for c-erbB-2 amplification, hormonal status, S-phase fraction, and mitotic index. The topo II-alpha index correlates better with the MIB1 index than with the S-phase fraction or mitotic index. The topo II-alpha expression in breast cancer ranges from low (topo II-alpha index <1) to high (topo II-alpha index = 86). Amplification of c-erbB-2 was observed in 4 of 28 cases (14%) but did not correlate with high topo II-alpha indices. We conclude that measurement of topo II-alpha in invasive breast cancer can be readily performed by immunohistochemical staining, and it gives information on the number of cycling tumor cells. In addition, because the enzyme is the molecular target of doxorubicin, the expression of the enzyme may relate also to the sensitivity or resistance of the tumor to doxorubicin-based chemotherapeutic protocols.

Epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF) negatively affect overall survival in carcinoma of the cervix treated with radiotherapy.

PURPOSE The purpose of this study was to examine a variety of biomarkers in carcinoma of the cervix to better characterize (1). the natural history of the disease, (2). response to radiotherapy (RT), and (3). potential for new therapeutic strategies. MATERIALS AND METHODS Fifty-five patients with Stage IB-IVA carcinoma of the cervix, treated with definitive intent RT, and on whom tumor tissue blocks were available were included in this study. Charts were reviewed for clinical parameters and disease status. Immunohistochemistry was performed for epidermal growth factor receptor (EGFR), vascular endothelial growth factor (VEGF), CD34, topoisomerase II alpha (topo-II), and cyclooxygenase-2 (COX-2). Univariate and multivariate Cox proportional hazards modeling was performed with disease-free survival (DFS) and overall survival (OS) as the end points. Biomarkers were evaluated for correlation between various prognostic factors. RESULTS In this series of 55 patients with carcinoma of the cervix treated with definitive RT, only stage was significant on univariate analysis for DFS (p < 0.0001). On univariate analysis, increasing FIGO stage (p < 0.0001) and membranous staining of EGFR (p < 0.037) indicated diminished OS. On multivariate analysis for DFS, COX-2, VEGF, and stage were significant (p = 0.012, p = 0.014, and p = 0.03, respectively), with increased expression indicating a worse prognosis. For OS, multivariate analysis revealed that VEGF, EGFR, and FIGO stage were significant (p = 0.005, p = 0.011, and p < 0.0001, respectively). Significant direct correlations were identified between VEGF and CD34 (p = 0.04), COX-2 and topo-II (p = 0.04), COX-2 and grade (p = 0.04), and tumor size and clinical stage (p = 0.04). CONCLUSION Multivariate analysis revealed that increased staining for VEGF and COX-2 indicated diminished DFS, and VEGF and EGFR identified patients at increased risk of death. A significant direct correlation between VEGF and CD34 implicates the process of angiogenesis. Topo-II is a proliferative marker and it correlated directly with COX-2, indicating that expression of COX-2 may be greater in more proliferative tumors. Increased expression of EGFR, VEGF, and COX-2 has identified patients with a worse prognosis in cancer of the cervix. These data support the investigation of therapeutics that target these proteins in carcinoma of the cervix.

Response to radiation therapy and prognosis in breast cancer patients with BRCA1 and BRCA2 mutations

BACKGROUND AND PURPOSE The purpose of this study is to evaluate overall survival in BRCA1 or BRCA2 breast cancer patients, describe presenting stage, review histologic findings and evaluate response to radiotherapy. MATERIALS AND METHODS A retrospective study was performed evaluating breast cancer patients with known mutations of BRCA1 or BRCA2. Patients from 12 different pedigrees were cross-referenced with the Utah Cancer Registry (UCR), histologic findings were verified and radiotherapy records were reviewed for acute response to treatment. Actuarial survival calculations were performed and patients were matched for age, date of diagnosis and tumor size. RESULTS Thirty breast cancer patients with BRCA1 mutations were found to have 34 breast cancers (four had bilateral metachronous lesions) and 20 breast cancer patients with BRCA2 mutations were found to have 22 breast cancers (two had bilateral metachronous disease). The median age at diagnosis was 49 years (range 21-77 years) and 42 years (range 23-83 years), respectively, for BRCA1 and BRCA2 patients. Unusual histologic types of breast cancers were represented with 7% (4/56) medullary and 5% (3/56) lobular carcinomas. Complete staging was possible for 63% (35/56) of cancers. Stages I, II, III and IV represented 26, 63, 6 and 6% of cancers, respectively. The most severe radiation reaction was moist desquamation which was self-limiting and developed in 29% (6/21) of irradiated patients. The mean follow-up was 9.8 and 7.5 years for BRCA1 and BRCA2 cancers, respectively. Kaplan-Meier survival analysis demonstrated 5-year survival values of 75% for BRCA1 patients, 73% for BRCA2 patients, 70% for matched controls and 69% for UCR controls. No statistically significant differences were evident between the groups at 5 or 10 years. CONCLUSIONS Despite their younger age at presentation, breast cancer patients harboring BRCAI or BRCA2 mutations present at a similar stage, display a normal acute reaction to radiotherapy and have a similar prognosis when compared with sporadic breast cancer patients.

Detection of EGFR- and HER2-activating mutations in squamous cell carcinoma involving the head and neck

Recent reports have indicated that mutations in the epidermal growth factor receptor-1 (EGFR) occur in about 7% of patients with squamous cell carcinoma of the head and neck. It is known that many patients with non-small-cell lung cancer who respond to the EGFR inhibitors gefitinib and erlotinib have tumors with EGFR-activating mutations. This might suggest that patients with head and neck squamous carcinoma, who also have tumors with EGFR-activating mutations, might represent a patient population who could benefit from gefitinib or erlotinib therapy. High-resolution melting amplicon analysis (HRMAA) is a recently described technique which can be used for screening tumor DNA isolated from paraffin blocks for tyrosine kinase-activating mutations. In this report we screened 24 cases of squamous cell carcinoma, either primary in the head and neck or secondarily involving the head and neck area, for activating mutations in EGFR exons 18, 19, 20, 21, and for HER2 exons 19 and 20. All cases were followed up by direct DNA sequencing. Two (8%) of the 24 cases were positive. One case was a maxillary sinus tumor which contained an exon 20-activating mutation (N771YinsG). Surprisingly, the other case was a primary squamous cell carcinoma of the skin which invaded the head and neck area only secondarily. This tumor contained an exon 19-activating mutation (G729E). No HER2-activating mutations were found. The presence of a small number of squamous cell carcinomas in the head and neck area with EGFR-activating mutations suggests the existence of a population of patients who could derive benefit from gefitinib or erlotinib therapy. HRMAA could serve as a screening method to easily and rapidly identify these patients.

Pathobiologic characteristics of hereditary breast cancer

Patients with hereditary breast cancer (HBC) present at a young age with breast cancers that show adverse pathological characteristics such as high nuclear grade, negative hormone receptor status, and high proliferation indices. Surprisingly, the clinical course has been reported to be comparable or improved compared with patients with nonhereditary breast cancer (non-HBC). To determine whether there are any molecular markers that might help explain this paradox between pathologically aggressive neoplasms in patients with HBC and the lack of extreme clinically aggressive disease, we studied several molecular parameters in a group of 34 breast cancer patients with mutations in either the BRCA1 or BRCA2 tumor suppressor genes and compared them with a group of 20 breast cancer patients with non-HBC. In general, patients with HBC had tumors that were of higher nuclear grade, contained a higher population of proliferating cells, showed increased expression of DNA topoisomerase II-alpha (topo II-alpha), lacked hormone receptors, and were more likely to show immunopositivity for the p53 tumor suppressor gene. Additionally, tumors from patients with HBC showed a decreased angiogenesis compared with controls. The decreased angiogenesis and the elevated expression of topo II-alpha (an anticancer drug target) may, in part, explain the lack of correlation between clinical course and histological characteristics in patients with HBC.

Detection of c-kit-activating mutations in gastrointestinal stromal tumors by high-resolution amplicon melting analysis

High-resolution amplicon melting analysis was used to scan for c-kit-activating mutations in exons 9, 11, 13, and 17 in 29 neoplasms diagnosed as gastrointestinal stromal tumors (GISTs). Immunohistochemically, 7 of 29 did not show strong CD 17 positivity and might represent true smooth muscle tumors or c-kit-negative GISTs. No c-kit-activating mutations were detected in the 7 CD117- cases by high-resolution amplicon melting analysis or direct DNA sequencing. Alterations in the remaining 22 CD117+ cases included 13 (59%) in exon 11, 2 (9%) in exon 9, 1 (5%) in exon 13, and none in exon 17. The genetic alterations consisted of point mutations and in-frame insertions, duplications, and deletions. In exon 11, 7 (54%) of 13 alterations have not been described previously. In 2 cases, the identical exon 11 mutation was observed in the primary tumor and a metastatic/recurrent lesion. In all cases, direct DNA sequencing confirmed that polymerase chain reaction products with an abnormal melting curve contained a mutation and products with a normal melting curve, a normal DNA sequence. High-resolution melting analysis can be used to scan DNA for potential c-kit-activating mutations and can aid in the diagnosis of GISTs.

Estrogen and progesterone receptors in colon tumors

Existing data suggest that there is a hormonal basis to the cause of colon cancer. In the present study, we evaluated the presence of estrogen receptors (ERs) and progesterone receptors (PRs) in colonic tumors from 156 women diagnosed with colon cancer in Utah from September 1991 through September 1994. Immunohistochemical staining with antibodies to ERs and PRs was performed on histologic sections prepared from paraffin blocks. None of the tumors were considered ER-positive; 1 tumor was PR-positive. Use of hormone replacement therapy was not associated with PR-positive tumors. These data do not support previous reports that suggest that colon tumors frequently have receptors for estrogen, progesterone, or both.