Cytogenetic studies in 11 patients with small cell carcinoma of the lung

Novel strategies for the treatment of small-cell lung carcinoma

Small-cell lung cancer (SCLC) is a disease with a poor prognosis and limited treatment options. Over the past 30 years, basic and clinical research have translated to little innovation in the treatment of this disease. The Study of Picoplatin Efficacy After Relapse (SPEAR) evaluated best supportive care with or without picoplatin for second-line SCLC treatment and failed to meet its primary end point of overall survival. As the largest second-line, randomized study in patients with SCLC, SPEAR provides an opportunity to critically examine the drug development model in this disease. In this Review, we discuss the current standard approach for the management of SCLC that progresses after first-line therapy, analyze the preliminary data that supported the evaluation of picoplatin in this setting, and critically evaluate the SPEAR trial design and results. Lastly, we present advances in the understanding of the molecular biology of SCLC that could potentially inform future clinical trials and hopefully lead to the successful development of molecular targeted agents for the treatment of this disease.

3p Abnormalities in Peripheral Lymphocytes in Small Cell Lung Cancer

3p abnormalities are the most frequent chromosome abnormalities in small cell lung cancer (SCLC). To date these abnormalities have only been observed in cells derived from tumor tissues. It is thought that cancer-related chromosome abnormalities in peripheral lymphocytes could help to predict cancer development, prognosis, and future metastasis. We report clonal and nonclonal 3p abnormalities in the peripheral lymphocytes of two patients with SCLC. A standard T-lymphocyte culture method and GTL banding technique were applied to the samples, and various clonal and nonclonal chromosome 3 abnormalities, i.e., −3, del(3)(p24), del(3)(p21), del(3)(p11), del(3)(q22), inv(3)(p14q29), and inv(3)(q21q29) were observed. Efforts have been made to understand if there are cancer-related chromosome abnormalities in lymphocytes and the suitability of these abnormalities to predict cancer development or metastases. As far as we know, this is the first report on chromosome 3 abnormalities in lymphocytes. Since 3p abnormalities are specific for SCLC, it is important to show that these cancer-related abnormalities can be found in blood cells.

High-grade neuroendocrine carcinomas display unique cytogenetic aberrations

Neuroendocrine tumors represent a spectrum of tumor types with different biologic and clinical features. The morphologic types include the low-grade typical and atypical carcinoids and the high-grade small cell and large cell neuroendocrine carcinomas (NECs). Cytogenetic descriptions of high-grade NECs are rare. Complete karyotypic descriptions of 34 high-grade NECs are reviewed: 7 extrapulmonary small cell NECs, 3 metastatic NECs of unknown primary, and 24 small cell lung carcinomas (SCLCs). Chromosomal deletions are more frequent than gains and often involve the entire chromosome arm. Typical aberrations are deletions of chromosome 3p, 5q, 10q, and 17p and gains of 1q, 3q, and 5p occurring as isochromosomes. Non-small cell lung cancers (NSCLCs) have different cytogenetic aberrations, but those with a metastatic phenotype display the identical aberrations as SCLC, a tumor known for its metastatic phenotype at onset. A genetic classification of lung cancer that incorporates the pattern of recurrent chromosome aberrations may be a better predictor of clinical outcome than a morphologic classification.

Chromosomal imbalances in human lung cancer

A wealth of cytogenetic data has demonstrated that numerous somatic genetic changes are involved in the pathogenesis of human lung cancer. Despite the complexity of the genomic changes observed in these neoplasms, recurrent chromosomal patterns have emerged. In this review, we summarize chromosomal alterations identified in small cell and non-small cell lung cancer, using classical and molecular cytogenetic techniques. These analyses have uncovered a set of chromosome regions implicated in lung cancer development and progression. However, many of the target genes remain unknown. Newer technology, such as array-CGH, when combined with cDNA microarrays and tissue microarrays, will facilitate the integration of genomic and gene expression data and pave the way toward a molecular classification of lung carcinomas. The molecular implications of consistent chromosome imbalances found in lung cancer to date are also discussed.

Hypotetraploidy in a patient with small cell carcinoma

While numerical and structural chromosomal abnormalities characterize many hematopoietic and nonhematopoietic malignancies, the occurrence of polyploidy is by and large rare. We report here an interesting patient with small cell carcinoma (SCC) and hypotetraploidy initially referred to us because of a question of acute nonlymphocytic leukemia, M3 subtype, with a question of a 15;17 translocation characteristic of acute promyelocytic leukemia. However, the patient did not have a 15;17 translocation and the final hematopathologic analysis of the bone marrow aspirates and immunohistochemistry studies subsequently revealed the patient to have SCC. Small cell carcinoma is a highly malignant and a very aggressive neoplasm. A review of the literature, using Medline, Cancerlit, and the Science Citation Index, revealed that in most, if not all, reports, the presence of polyploidy is noted as a rare entity. In leukemia, reports of polyploidy point to a distinct category of patients with a poor risk for which more intensive treatment is needed. Limited information is currently available to assess the risk of polyploidy in small cell carcinoma. Our case is important not only because of the relative rarity of polyploidy, but also because insights gained from the study of this and other similar patients may help shed additional light on the mechanism of carcinogenesis, which is not fully known to date. As polyploidization is a manifestation of genetic instability and as genetic instability has been implicated in the genesis and progression of many cancers, it is perhaps not too surprising that polyploidy in our case was associated with a poor disease outcome. The patient has since expired.

A combined approach of conventional and molecular cytogenetics for detailed karyotypic analysis of the small cell lung carcinoma cell line U2020

Until recently the ability to analyze complex karyotypic rearrangements was totally dependent upon light microscopy of G-banded chromosomes. Developments in the area of molecular cytogenetics have revolutionized such analysis, making it possible to determine the nature of complex rearrangements. An extensive analysis has been made of the small cell lung carcinoma (SCLC) cell line U2020, using a combined approach of conventional and molecular cytogenetics, enabling a highly detailed karyotype to be constructed revealing rearrangements previously undetected by G-banding alone. This approach offers the opportunity to reassess other tumor karyotypes, particularly those of high complexity found in solid tumors, for tumor-specific consistent rearrangements indecipherable by conventional karyotyping.

Cytogenetic findings in thirty lung carcinoma patients

Primary tissue cultures of human lung tumors were prepared from 30 cases of which 16 were diagnosed as squamous cell carcinoma, six adenocarcinoma, four adenosquamous cell carcinoma, three large cell carcinoma, and one small cell lung carcinoma. Chromosomal abnormalities were observed in 26 cases by cytogenetic studies with a GTG banding technique. Specific chromosome bands frequently involved in structural abnormalities were seen on 1p11, 1q11, 2p10, 6p10, 7q11, 7q22, 7q32, 8q22, 9q22, 11q11, 21q10, and Xq24. We assumed that especially i(2)(p10), i(9)(p10), i(21)(q10), t(11;12), t(14;15), del(X)(q24), and loss of the Y chromosome may play a role in the development of lung cancer as secondary changes. In this way, our cytogenetic findings provide evidence that multiple genetic lesions are associated with the pathogenesis of lung cancer.

Deletions of the short arm of chromosome 3 in solid tumors and the search for suppressor genes

The concept that cells can become malignant upon the elimination of parts of chromosomes inhibiting cell division dates back to Boveri in 1914. Deletions occurring in tumor cells are therefore considered a first indication of possible locations of tumor suppressor gene. Approaches used to localize and identify the paradigm of tumor suppressors, RB1, have also been applied to localize tumor suppressor genes on 3p, the short arm of chromosome 3. This review discusses the methodological advantages and limitations of the various approaches. From a review of the literature on losses of 3p in different types of solid tumors it appears that some tumor types show involvement of the same region, while between others the regions involved clearly differ. Also discussed are results of functional assays of tumor suppression by transfer of part of chromosome 3 into tumor cell lines. The likelihood that a common region of deletions would contain a tumor suppressor is strongly enhanced by coincidence of that region with a chromosome fragment suppressing tumorigenicity upon introduction in tumor cells. Such a situation exists for a region in 3p21.3 as well as for one or more in 3p12-p14. The former region is considered the location of a lung cancer suppressor. The same gene or a different one in the same region may also play a role in the development of other cancers including renal cell cancer. In the latter cancer, there may be additional roles of the VHL region and/or a 3p12-p14 region. The breakpoint region of a t(3;8) originally found to be constitutively present in a family with hereditary renal cell cancer now seems to be excluded from such a role. Specific genes on 3p have been suggested to act as suppressor genes based on either their location in a common deletion region, a markedly reduced expression or presence of aberrant transcripts, their capacity to suppress tumorigenicity upon transfection in to tumor cells, the presumed function of the gene product, or a combination of several of these criteria. A number of genes are evaluated for their possible role as a tumor suppressor according to these criteria. General agreement on such a role seems to exist only for VHL. Though hMLH1 plays an obvious role in the development of specific mismatch repair-deficient cancers, it cannot revert the tumor phenotype and therefore cannot be considered a proper tumor suppressor. The involvement of VHL and MLH1 also in some specific hereditary cancers allowed to successfully apply linkage analysis for their localization. TGFBR2 might well have a tumor suppressor function. It does reduce tumorigenicity upon transfection. Other 3p genes coding for receptor proteins THRB and RARB, are unlikely candidates for tumor suppression. Present observations on a possible association of FHIT with tumor development leave a number of questions unanswered, so that provisionally it cannot be considered a tumor suppressor. Regions that have been identified as crucial in solid tumor development appear to be at the edge of synteny blocks that have been rearranged through the chromosome evolution which led to the formation of human chromosome 3. Although this may merely represent a chance occurrence, it might also reflect areas of genomic instability.

Merkel cell carcinoma. Histopathology, immunohistochemistry, and cytogenetic analysis

BACKGROUND

Merkel cell carcinoma (MCC) is a cutaneous neoplasm, histopathologically difficult to differentiate from other small blue cell neoplasms. Immunohistochemical and ultrastructural analyses are usually helpful in differentiating these neoplasms. Recently, cytogenetic analysis has emerged as a potential tool in the diagnosis of solid neoplasms, including MCC.

OBJECTIVE

To describe the immunohistochemical and cytogenetic features of a case of primary MCC and to review the cytogenetics literature on MCC.

METHODS

Formalin-fixed tissue was processed routinely and labeled with a battery of antibodies. Metaphase cells from fresh tissue were prepared by Giemsa banding.

RESULTS

Histopathologically, there were irregular aggregates of pyknotic cells with little cytoplasm. Immunohistochemically, the neoplastic cells stained positive for neurofilament, cytokeratin, neuron-specific enolase, and epithelial membrane antigen. Leucocyte common antigen, S-100, 013, and chromogranin were negative. Karyotyping of neoplastic cells showed loss of chromosome Y (-Y).

CONCLUSIONS

Coexpression of cytokeratin and neurofilament is characteristic of MCC and allows it to be differentiated from similar neoplasms. The significance of Y chromosome loss is unclear. Further cytogenetic analyses are warranted to identify genetic mutations significant to the pathogenesis of MCC.

Molecular markers for the diagnosis and prognosis of lung cancer

Molecular probes for lung cancer have greatly increased the understanding of the biology of this disease and the preneoplastic changes that precede it. They have confirmed and extended the clinical, pathologic, and biologic reasons for the primary division of lung cancers into small cell and non-small cell lung cancer types. Many molecular changes are present in lung cancers and involve dominant oncogenes and recessive growth regulatory genes. Clinical application of these markers will aid diagnosis, classification, and clinical management.

Involvement of the RAF1 locus, at band 3p25, in the 3p deletion of small-cell lung cancer

The ability to establish long-term cell lines of small-cell lung cancer (SCLC) has provided an in vitro model for the disease. We report on the characterization of 10 new human SCLC cell lines established from 34 cytopathologically positive specimens. Based on morphologic and biochemical characterization, growth properties, and expression of MYC and neuroendocrine properties, eight cell lines were categorized as "classic" and two cell lines as "variant". Cytogenetic examination revealed loss of all or part of 3p in all nine SCLC cell lines analyzed. The smallest deletion in common was found at 3p21-3p25. Restriction fragment length polymorphism (RFLP) analyses with probes for 3p were performed for correlation with karyotypic data and supported the cytogenetic findings. In 21 SCLC specimens (cell lines and tumor tissue) with normal DNA, used for comparison, we observed loss of heterozygosity at RAF1 (3p25) in ten of ten informative pairs by using two RFLPs from the RAF1 locus. In addition, loss of heterozygosity was noted in nine of 10 pairs examined with DNF15S2 (3p21) and four of four with D3S3 (3p14). Analysis of cell lines and tumor specimens that lacked paired normal tissue showed a homozygous pattern with the RAF1 probes in all 18 cases. Northern blots revealed significant expression of RAF1 in all cell lines tested. The transcript size was normal. The cytogenetic and RFLP data suggest that the RAF1 locus at 3p25 is involved in the chromosomal deletion of SCLC.