Steven J. Kussick

Escape from Therapy-Induced Accelerated Cellular Senescence in p53-Null Lung Cancer Cells and in Human Lung Cancers

Accelerated cellular senescence (ACS) has been described for tumor cells treated with chemotherapy and radiation. Following exposure to genotoxins, tumor cells undergo terminal growth arrest and adopt morphologic and marker features suggestive of cellular senescence. ACS is elicited by a variety of chemotherapeutic agents in the p53-null, p16-deficient human non-small cell H1299 carcinoma cells. After 10 to 21 days, infrequent ACS cells (1 in 10(6)) can bypass replicative arrest and reenter cell cycle. These cells express senescence markers and resemble the parental cells in their transcription profile. We show that these escaped H1299 cells overexpress the cyclin-dependent kinase Cdc2/Cdk1. The escape from ACS can be disrupted by Cdc2/Cdk1 kinase inhibitors or by knockdown of Cdc2/Cdk1 with small interfering RNA and can be promoted by expression of exogenous Cdc2/Cdk1. We also present evidence that ACS occurs in vivo in human lung cancer following induction chemotherapy. Viable tumors following chemotherapy also overexpress Cdc2/Cdk1. We propose that ACS is a mechanism of in vivo tumor response and that mechanisms aberrantly up-regulate Cdc2/Cdk1 promotes escape from the senescence pathway may be involved in a subset of tumors and likely accounts for tumor recurrence/progression.

Determining true HER2 gene status in breast cancers with polysomy by using alternative chromosome 17 reference genes: implications for anti-HER2 targeted therapy.

PURPOSE The ratio of human epidermal growth factor receptor 2 (HER2) to CEP17 by fluorescent in situ hybridization (FISH) with the centromeric probe CEP17 is used to determine HER2 gene status in breast cancer. Increases in CEP17 copy number have been interpreted as representing polysomy 17. However, pangenomic studies have demonstrated that polysomy 17 is rare. This study tests the hypothesis that the use of alternative chromosome 17 reference genes might more accurately assess true HER2 gene status. PATIENTS AND METHODS In all, 171 patients with breast cancer who had HER2 FISH that had increased mean CEP17 copy numbers (> 2.6) were selected for additional chromosome 17 studies that used probes for Smith-Magenis syndrome (SMS), retinoic acid receptor alpha (RARA), and tumor protein p53 (TP53) genes. A eusomic copy number exhibited in one or more of these loci was used to calculate a revised HER2-to-chromosome-17 ratio by using the eusomic gene locus as the reference. RESULTS Of 132 cases classified as nonamplified on the basis of their HER2:CEP17 ratios, 58 (43.9%) were scored as amplified by using alternative chromosome 17 reference gene probes, and 13 (92.9%) of 14 cases scored as equivocal were reclassified as amplified. Among the cases with mean HER2 copy number of 4 to 6, 41 (47.7%) of 86 had their HER2 gene status upgraded from nonamplified to amplified, and four (4.7%) of 86 were upgraded from equivocal to amplified. CONCLUSION Our results support the findings of recent pangenomic studies that true polysomy 17 is uncommon. Additional FISH studies that use probes to the SMS, RARA, and TP53 genes are an effective way to determine the true HER2 amplification status in patients with polysomy 17 and they have important potential implications for guiding HER2-targeted therapy in breast cancer.

High concordance between immunohistochemistry and fluorescence in situ hybridization testing for HER2 status in breast cancer requires a normalized IHC scoring system

The American Society of Clinical Oncologists and College of American Pathologists have recently released new guidelines for laboratory testing of HER2 status in breast cancer, which require high levels (95%) of concordance between immunohistochemistry positive (3+) and fluorescence in situ hybridization-amplified cases, and between immunohistochemistry negative (0/1+) and fluorescence in situ hybridization-nonamplified cases; these required levels of concordance are significantly higher than those found in most published studies. We tested the hypothesis that a modification of the HER2 immunohistochemistry scoring system could significantly improve immunohistochemistry and fluorescence in situ hybridization concordance. A total of 6604 breast cancer specimens were evaluated for HER2 status by both immunohistochemistry and fluorescence in situ hybridization using standard methodologies. Results were compared when the standard immunohistochemistry scoring system was replaced by a normalized scoring system in which the HER2 score was derived by subtracting the score on the non-neoplastic breast epithelium from that on the tumor cells. Among the 6604 tumors, using a non-normalized immunohistochemistry scoring system, 267/872 (30.6%) of the immunohistochemistry 3+ cases proved to be fluorescence in situ hybridization nonamplified, whereas using the normalized scoring system only 30/562 (5.3%) of immunohistochemistry 3+ cases proved to be ‘false positive’. The concordance rate between immunohistochemistry 3+ and fluorescence in situ hybridization-amplified cases using the normalized scoring method was 94.7%, whereas the concordance using the non-normalized method was only 69.4%. Extremely high concordance between immunohistochemistry and fluorescence in situ hybridization assessment of HER2 status in breast cancer is achievable, but to attain this high level of concordance, modification of the FDA-approved immunohistochemistry scoring system is required.

Using 4-Color Flow Cytometry to Identify Abnormal Myeloid Populations

CONTEXT The diagnosis of myeloproliferative disorders (MPDs) and myelodysplastic syndromes (MDSs) has historically relied on combining clinical information with the morphologic features of the peripheral blood and bone marrow to reach a final diagnosis. Objective evidence of a myeloid stem cell neoplasm in the form of a clonal cytogenetic abnormality is provided in only 30% to 40% of the non-chronic myeloid leukemia (CML) chronic MPDs (non-CML MPDs) and in a similar percentage of the MDSs. OBJECTIVE To identify normal patterns of antigen expression during myeloid maturation and to determine whether flow cytometric evaluation of myeloid maturation represents an additional objective way to assess the likelihood of a stem cell neoplasm. DESIGN We retrospectively evaluated 4-color flow cytometry data from more than 400 bone marrow aspirates obtained since 1998 from patients suspected of having a non-CML MPD or an MDS. RESULTS Reproducible patterns of antigen expression were seen in normal myeloid maturation as well as in benign reactive settings such as marrow regeneration. In addition, we summarize data, presented in detail elsewhere, from a retrospective comparison of the sensitivity of flow cytometry with conventional cytogenetics for a large number of bone marrow aspirates on which both types of studies were performed. These data indicate that more than 90% of non-CML MPD and MDS cases with a clonal cytogenetic abnormality will be identified as abnormal by 4-color flow cytometry, and they therefore validate the use of flow cytometry in the diagnosis of these disorders. CONCLUSIONS In experienced laboratories, 4-color flow cytometry represents a valuable addition to the workup of non-CML MPDs and MDSs.

Identification and purification of classical Hodgkin cells from lymph nodes by flow cytometry and flow cytometric cell sorting

We demonstrate the feasibility of using flow cytometry (FC) to identify the Hodgkin and Reed-Sternberg (HRS) cells of classical Hodgkin lymphoma (CHL). Initial flow cytometric studies of the HRS cell line L1236 demonstrated potentially useful antigens for identifying HRS cells. L1236 cells spontaneously bound normal T cells, analogous to the T-cell rosetting of HRS cells seen in tissue sections of CHL, but these interactions could be blocked by using a cocktail of unlabeled antibodies to 4 adhesion molecules. Among 27 lymph nodes involved by CHL, FC enabled HRS cells to be identified in 89%, whereas none of 29 non-CHL neoplasms or 23 reactive lymph nodes demonstrated HRS populations. Of the CHL cases, 82% demonstrated interactions between HRS cells and T cells that could be disrupted with blocking antibodies. Flow cytometric cell sorting experiments demonstrated typical HRS cytomorphologic features among the purified cells. FC may offer an alternative to immunohistochemical analysis in confirming the diagnosis of CHL in certain cases, and, through cell sorting, it provides a means of rapidly isolating pure HRS cells.

A distinctive nuclear morphology in acute myeloid leukemia is strongly associated with loss of HLA-DR expression and FLT3 internal tandem duplication

In a 5-year survey of nonpromyelocytic/nonmonocytic acute myeloid leukemias (AMLs) diagnosed in the University of Washington Hematopathology Laboratory, we identified 19 cases containing distinctive, cup-like nuclear indentation in 10% or more of the blasts (‘AML-cuplike’). Fourteen of these cases (74%) demonstrated near-complete loss of HLA-DR expression, while the other five cases showed partial loss of HLA-DR. A total of 16 of the cases (84%) demonstrated internal tandem duplication (ITD) of the Flt3 gene. When compared to a selected set of AMLs lacking this nuclear morphology, AML-cuplike was significantly more likely to lack HLA-DR and CD34 expression, to express CD123 without CD133, to have a normal karyotype, and to harbor the Flt3 ITD. To characterize AML-cuplike in an unselected series of AMLs, we analyzed 42 consecutive nonpromyelocytic/nonmonocytic AMLs diagnosed in our laboratory during a 6-month period in 2002. Strikingly, in this unselected series, there was a statistically significant coincidence of invaginated nuclear morphology, loss of HLA-DR, and presence of the Flt3 ITD beyond that expected if these three features were unrelated, suggesting that AMLs with these three features may represent a distinct AML subset.

Novel FLT3 point mutations within exon 14 found in patients with acute myeloid leukaemia

Internal tandem duplications in FLT3 are the most common mutation in acute myeloid leukaemia (AML), with agarose gel electrophoresis of polymerase chain reaction products (PCR/agarose) being the screening method of choice for these mutations. As PCR/agarose screening does not detect small mutations, single‐stranded conformational polymorphism analyses (PCR/SSCP) were used in an attempt to identify previously unrecognized point mutations in FLT3 exons 14 and 15 of 140 AML patients, using newly designed primers that anneal within intron sequences. Novel missense point mutations were found in exon 14, suggesting additional investigations should be performed in AML and other haematopoietic malignancies, using this sensitive technique.

Four-color flow cytometry identifies virtually all cytogenetically abnormal bone marrow samples in the workup of non-CML myeloproliferative disorders.

Because of the relative insensitivity of conventional cytogenetics for identifying abnormalities in the non-chronic myelogenous leukemia (CML) myeloproliferative disorders (MPDs), we directly compared the abilities of flow cytometry and cytogenetics to identify such cases. We retrospectively identified 66 patients whose bone marrow samples were evaluated for abnormalities of myeloid antigen expression by 4-color flow cytometry as part of the workup to rule out a non-CML MPD. The patients all had concurrent cytogenetic evaluation of the marrow and no evidence of the t(9;22). Compared with a series of 12 normal bone marrow samples, 30 of 66 specimens demonstrated definitive flow cytometric abnormalities, while the other 36 cases had normal (21 cases) or indeterminate (15 cases) results, with the latter showing only mild antigenic alterations. Strikingly, clonal cytogenetic abnormalities were found in 11 (37%) of the 30 cases with flow cytometric abnormalities, compared with no cytogenetic abnormalities among the 36 normal and indeterminate cases. The most common abnormal myeloid-associated antigens included HLA-DR, CD13, and CD33. In experienced laboratories, 4-color flow cytometry represents a useful method to help distinguish benign from neoplastic marrow in the workup of non-CML MPDs.

Intravascular large B-cell lymphoma involving hemangiomas: an unusual presentation of a rare neoplasm

We report the clinicopathological features of two cases of intravascular large B-cell lymphoma involving cutaneous hemangiomas. The cases were identified from the consultation files of two of the authors. Both patients were women, 64 and 55 years of age, who presented with long-standing cutaneous hemangiomas of the posterior scalp and left shoulder, respectively. The lesions were brought to medical attention by an increase in size and change in color. Biopsies and immunohistochemical evaluation of the hemangiomas revealed extensive involvement by intravascular large B-cell lymphoma. The neoplastic cells were diffusely positive for CD20 in both cases and negative for CD3, pan-cytokeratin (AE1/AE3), epithelial membrane antigen, S-100, Factor VIII-related antigen, CD34 and CD31. Disease was limited to the hemangiomas in both patients. Treatment consisted of chemotherapy (both patients) and adjuvant radiation therapy (one patient). One patient had a recurrence of disease 33 months after initial diagnosis, leading to an autologous stem cell transplant. The other patient is without evidence of disease 27 months after initial diagnosis. Although this is a rare neoplasm, it is important to consider intravascular large B-cell lymphoma in the differential diagnosis of vascular lesions containing intravascular neoplastic cells.

Identification of genes whose expression patterns differ in benign lymphoid tissue and follicular, mantle cell, and small lymphocytic lymphoma

Improved methods for diagnosing small B-cell lymphomas (SBCLs) and predicting patient response to therapy are likely to result from the ongoing discovery of molecular markers that better define these malignancies. In this report, we identify 120 genes whose expression patterns differed between reactive lymph node tissue and three types of SBCL: follicular lymphoma, mantle cell lymphoma, and chronic lymphocytic leukemia/small lymphocytic lymphoma. Whereas previously published studies have generally analyzed the gene expression profiles of one type of SBCL, work presented in this paper was intended to identify genes that are differentially expressed between three SBCL subtypes. This analysis was performed using mRNA pooled from multiple specimens representing each tissue type. Quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) was used to validate the differential expression of 23 of these genes. Among the 23 validated genes were cyclin D1 (CCND1) and B-cell CLL/lymphoma 2, which have well-known roles in lymphoma pathogenesis. The remaining 21 genes have no currently established role in lymphoma development. Using qRT-PCR, the expression of CCND1 and seven additional genes was further studied in a panel of individual specimens. Genes identified in this study are of biological interest and represent candidate diagnostic markers.