Production of stem cell factor and expression of c-kit in human rhabdomyosarcoma cells: lack of autocrine growth modulation

Nöroblastom hastalarında telomeraz aktivitesinin prognoz ile ilişkisi

Amaç: Bu çalışmanın amacı, telomeraz aktivitesinin nöroblastomlu hastaların klinik özellikleri ve sağkalımı üzerindeki etkisini araştırmaktı. Gereç ve Yöntem: Bu çalışma, Çukurova Üniversitesi Tıp Fakültesi Pediatrik Onkoloji Anabilim Dalı'nda 2011-2019 yılları arasında nöroblastom tanısı konulan 87 hastanın daha önce alınan patoloji preparatlarında telomeraz aktivitesi incelenerek yapılmıştır. Bulgular: Çalışmamıza 46'sı erkek (%52.9) ve 41'i kadın (%47.1) olmak üzere toplam 87 hasta dahil edildi. Tanı anındaki ortanca yaş 3.0 (0.08-15) yıldı. Çalışmaya alınan 23 (%26.4) hastada telomeraz aktivitesi mevcutken 64 (%73.6) hastada telomeraz aktivitesi yoktu. 8 yıla kadar telomeraz aktivitesi olan hastaların genel sağkalımı (OS) %84 iken olaysız sağkalım (EFS) %56 idi. Telomeraz aktivitesi olmayan hastalar 8 yıla kadar %93 OS'ye sahipken, EFS %70 idi. Telomeraz aktivitesi olan ve olmayan hastalar arasında cinsiyet, yaş, evre, risk grubu, relaps, mycn amplifikasyonu, OS ve EFS açısından anlamlı bir ilişki yoktu. Sonuç: Bu çalışmada, telomeraz aktivitesi ile nöroblastom hastalarının klinik özellikleri ve sağkalımları arasında anlamlı bir fark bulunmadı. Daha fazla sayıda hastanın dahil edileceği prospektif çalışmalar telomeraz aktivitesinin nöroblastom hastalarının prognozu üzerine etkisini daha net bir şekilde ortaya koyacaktır.

Proof-of-concept rare cancers in drug development: the case for rhabdomyosarcoma

Rare diseases typically affect fewer than 200,000 patients annually, yet because thousands of rare diseases exist, the cumulative impact is millions of patients worldwide. Every form of childhood cancer qualifies as a rare disease-including the childhood muscle cancer, rhabdomyosarcoma (RMS). The next few years promise to be an exceptionally good era of opportunity for public-private collaboration for rare and childhood cancers. Not only do certain governmental regulation advantages exist, but these advantages are being made permanent with special incentives for pediatric orphan drug-product development. Coupled with a growing understanding of sarcoma tumor biology, synergy with pharmaceutical muscle disease drug-development programs, and emerging publically available preclinical and clinical tools, the outlook for academic-community-industry partnerships in RMS drug development looks promising.

Kit expression in spindle cell rhabdomyosarcoma can possibly create a different approach for its tumorigenesis and therapy

The use of a relatively nontoxic tyrosine kinase receptor inhibitor, imatinib mesylate (IM) (STI-571), has increasingly become a valuable therapeutic alternative in some KIT (CD117)-overexpressing neoplasms potentially because of the presence of KIT-activating mutations. As the treatment eligibility for this drug hinges on CD117 expression, KIT immunostaining has recently been widely examined in various different tumors. We examined CD117 expression in pediatric embryonal rhabdomyosarcomas (RMSs) to identify its eventual prognostic impact and to evaluate its effect on tumorigenesis. This study included two spindle cell (leiomyomatous) variants, two botryoid variants, and 21 conventional embryonal RMSs. Sections from paraffin-embedded tumor samples were immunostained by a standard SABC technique using c-kit polyclonal antibody with antigen retrieval. In all the series, the percentage of CD117 positivity was 12%. Staining was strong in two of two spindle cell variants, in zero of two botryoid variants, and in one of 21 conventional embryonal RMSs. In Spearman's correlation analysis, there was statistical relationship between the presence of CD117 expression and the histological subtype of RMS. Kaplan-Meier analysis revealed no prognostic significance of CD117 expression for survival. The present study demonstrated a very limited expression of CD117 in pediatric embryonal RMS other than in the spindle cell variant. This finding suggested that the stem cell factor/c-kit pathway may be implicated in the tumorigenesis of spindle cell RMSs. Therefore, the mutation of c-kit gene must be prospectively examined in larger series of RMSs. If it can be verified that tissue expression of CD117 reflects the mutation of c-kit gene, IM can be considered a targeted therapy for CD117-expressing RMSs, particularly the spindle cell variant.

Endothelin-3 production by human rhabdomyosarcoma: a possible new marker with a paracrine role

Several autocrine and paracrine growth factor circuits have been found in human rhabdomyosarcoma cells. In this study we show that endothelin-3 (ET-3), a vasoactive peptide, is produced by human rhabdomyosarcoma cell lines, whereas it is not expressed by human sarcoma cell lines of non-muscle origin. We did not find evidence of a significant autocrine loop; nevertheless ET-3 produced by rhabdomyosarcoma cells can act as a paracrine factor, since it promotes migration of endothelial cells. Moreover ET-3 is present in plasma of mice bearing xenografts of human rhabdomyosarcoma cells, and may be potential new marker of the human rhabdomyosarcoma to be studied further.

KIT (CD117): a review on expression in normal and neoplastic tissues, and mutations and their clinicopathologic correlation

CD117 (KIT) is a type III receptor tyrosine kinase operating in cell signal transduction in several cell types. Normally KIT is activated (phosphorylated) by binding of its ligand, the stem cell factor. This leads to a phosphorylation cascade ultimately activating various transcription factors in different cell types. Such activation regulates apoptosis, cell differentiation, proliferation, chemotaxis, and cell adhesion. KIT-dependent cell types include mast cells, some hematopoietic stem cells, germ cells, melanocytes, and Cajal cells of the gastrointestinal tract, and neoplasms of these cells are examples of KIT-positive tumors. Other KIT-positive normal cells include epithelial cells in skin adnexa, breast, and subsets of cerebellar neurons. KIT positivity has been variably reported in sarcomas such as angiosarcoma, Ewing sarcoma, synovial sarcoma, leiomyosarcoma, and MFH; results of the last three are controversial. The variations in published data may result from incomplete specificity of some polyclonal antibodies, possibly contributed by too high dilutions. Also, KIT is expressed in pulmonary and other small cell carcinomas, adenoid cystic carcinoma, renal chromophobe carcinoma, thymic, and some ovarian and few breast carcinomas. A good KIT antibody reacts with known KIT positive cells, and smooth muscle cells and fibroblasts are negative. KIT deficiency due to hereditary nonsense/missense mutations leads to disruption of KIT-dependent functions such as erythropoiesis, skin pigmentation, fertility, and gastrointestinal motility. Conversely, pathologic activation of KIT through gain-of-function mutations leads to neoplasia of KIT-dependent and KIT-positive cell types at least in three different systems: mast cells/myeloid cells--mastocytosis/acute myeloid leukemia, germ cells--seminoma, and Cajal cells--gastrointestinal stromal tumors (GISTs). KIT tyrosine kinase inhibitors such as imatinib mesylate are the generally accepted treatment of metastatic GISTs, and their availability has prompted an active search for other treatment targets among KIT-positive tumors such as myeloid leukemias and small cell carcinoma of the lung, with variable and often nonconvincing results.

Establishment and characterization of a KIT-positive and stem cell factor-producing cell line, KTHOS, derived from human osteosarcoma

Osteosarcoma is a malignant bone tumor that commonly affects adolescents and young adults. In the present study a human osteosarcoma cell line, KTHOS, was established from a primary osteosarcoma lesion in the distal femur of a 16-year-old girl. After 106 passages, the KTHOS cell line retained the biological characteristics of osteosarcoma. The KTHOS cells had spindle to pleomorphic cytoplasm with round to ovoid nuclei containing multiple prominent nucleoli, as expected based on the mesodermic origin of osteoblasts. The KTHOS cells were immunoreactive for osteocalcin, osteonectin, stem cell factor (SCF), and KIT (CD117). Reverse transcriptase-polymerase chain reaction indicated that the KTHOS cell line expressed mRNA for SCF and KIT. The KTHOS cells produced relatively high amounts of soluble SCF as determined by enzyme-linked immunosorbent assay. The results suggest that cell proliferation of the KTHOS cell line might be involved in autocrine and/or paracrine loops of the SCF/KIT signaling system. The KTHOS cell line is a novel human osteosarcoma cell line that releases SCF and expresses KIT. This cell line can be used for studies to explore the mechanisms for oncogenesis of human osteosarcomas.

Expression of c-kit in Ewing family of tumors: a comparison of different immunohistochemical protocols

Ewing sarcoma is a small round blue cell tumor with a high incidence of metastasis and poor survival. The tyrosine kinase receptor, c-kit, is a growth factor receptor that is expressed in a variety of tumors including Ewing sarcoma. Blockade of c-kit by imatinib mesylate (Gleevec; Novartis Pharmaceuticals Corp, East Hanover, NJ) has been successfully used in the treatment of chronic myelogenous leukemia and gastrointestinal tumors. Detection of c-kit expression in Ewing sarcoma indicates a possible role of c-kit in tumor progression and a potential use of anti-c-kit therapy in Ewing sarcoma. Ki-67 is a proliferation marker found at all stages of the cell cycle. Expression of c-kit and Ki-67 was studied in 17 patients with Ewing sarcoma. Sections from paraffin-embedded tumor samples were immunostained, using standard immunohistochemical protocols, with c-kit and Ki-67 monoclonal antibodies, polyclonal c-kit antibody without antigen retrieval, and c-kit polyclonal antibody with antigen retrieval. Eleven out of 17 cases (65%) stained with c-kit monoclonal antibody; the staining was diffuse in 6/17 (35%) cases. C-kit expression did not correlate with Ki-67 proliferation rates. Using the polyclonal c-kit-antibody without antigen retrieval methods, c-kit expression was demonstrated in 1/11 (9%) cases. Incorporating antigen retrieval methods, c-kit expression increased to 53%. Concordance between monoclonal antibodies in detecting c-kit expression was observed in 12/17 cases (71%). We conclude that c-kit is variably expressed in Ewing sarcoma, using either monoclonal or polyclonal antibodies. Detection of c-kit expression in Ewing sarcoma improves with the use of antigen retrieval methods.

Hodgkin and Reed-Sternberg cells express functional c-kit receptors and interact with primary fibroblasts from Hodgkin's disease-involved lymph nodes through soluble and membrane-bound stem cell factor

Classic Hodgkin's disease (cHD) is a lymphoid neoplasia characterized by few malignant Hodgkin and Reed-Sternberg (H-RS) cells, embedded in an abundant background of non-tumour cells. We have previously demonstrated the expression in primary H-RS cells of the receptor tyrosine kinase (RTK) c-kit; here we describe its functional role in the cross-talk between H-RS cells themselves with neighbouring cell populations. In particular, we analysed the expression of c-kit and its ligand stem cell factor (SCF) in a panel of HD-derived cell lines and fibroblasts from HD-involved lymph nodes (HDF). While c-kit was expressed by HD-derived cell lines, usually in the absence of SCF, this latter molecule, in its soluble and/or membrane-bound (mb) form, was in turn expressed at a high level by primary HDF. In vitro adhesion between HD-derived cell lines and HDF was mainly mediated by c-kit/SCF interactions, and this phenomenon was significantly inhibited by an excess of soluble SCF or by neutralizing anti-c-kit monoclonal antibodies. Furthermore, both soluble and mb-SCF increased growth and colony survival of HD-derived cell lines; these effects were significantly enhanced upon co-stimulation of H-RS cells with interleukin 9. Finally, soluble SCF was able to partially rescue H-RS cells from apoptosis induced by serum starvation. Taken together, our data indicated the expression of functional c-kit receptor by H-RS cells and suggests a role of SCF in the pathobiology of cHD.

C-kit expression in pediatric solid tumors: a comparative immunohistochemical study

The stem cell factor/c-kit tyrosine kinase receptor pathway has been shown to be important for tumor growth and progression in several cancers, including mast cell diseases, gastrointestinal stromal tumor, acute myeloid leukemia, small cell lung carcinoma, and Ewing sarcoma. Studies using the oral agent STI-571 (Gleevec, Novartis), an inhibitor of the tyrosine kinases bcr-abl, c-kit, and PDGFR, have shown significant responses in patients with chronic myelogenous leukemia and gastrointestinal stromal tumor. With the aim of identifying additional groups of tumors that may use the stem cell factor/c-kit pathway and secondarily may be responsive to STI-571 treatment, this study surveyed 151 primary tumors from patients treated at St. Jude Children's Research Hospital for immunohistochemical expression of c-kit. Formalin-fixed, paraffin-embedded sections were stained with rabbit polyclonal anti-human c-kit (CD117, Dako) using standard avidin-biotin-peroxidase complex technique, antigen retrieval, and an automated stainer. Strong, diffuse staining for c-kit was seen in a proportion of synovial sarcomas, osteosarcomas, and Ewing sarcomas. Strong, diffuse staining was less common in neuroblastomas, Wilms' tumors, and rhabdomyosarcomas and was negative in alveolar soft part sarcomas and desmoplastic small round cell tumors. Tumors with strong, diffuse staining for c-kit in a pattern similar to gastrointestinal stromal tumor may represent suitable targets for new therapeutic agents.

The metastatic ability of Ewing's sarcoma cells is modulated by stem cell factor and by its receptor c-kit

Ewing's sarcoma is a primitive highly malignant tumor of bone and soft tissues usually metastasizing to bone, bone marrow, and lung. Growth factor receptors and their ligands may be involved in its growth and dissemination. We analyzed the expression of c-kit and its ligand stem cell factor (SCF) in a panel of six Ewing's sarcoma cell lines. All cell lines exhibited substantial levels of surface c-kit expression, and five of six displayed transmembrane SCF on the cell surface. Expression of c-kit was down-modulated in all lines by exposure to exogenous SCF. The SCF treatment was able to confer to cells a growth advantage in vitro, due both to an increase in cell proliferation and to a reduction in the apoptotic rate. When used in the lower compartment of a migration chamber, SCF acted as a strong chemoattractant for Ewing's sarcoma cells. The pretreatment of cells with SCF reduced their chemotactic response to SCF. In athymic nude mice, Ewing's sarcoma cells injected intravenously metastasized to the lung and to a variety of extrapulmonary sites, including bone and bone marrow. Metastatic sites resembled those observed in Ewing's sarcoma patients and corresponded to SCF-rich microenvironments. The in vitro pretreatment of cells with SCF strongly reduced the metastatic ability of Ewing's sarcoma cells, both to the lung and to extrapulmonary sites. This could be dependent on the down-modulation of c-kit expression observed in SCF-pretreated cells, leading to a reduced sensitivity to the chemotactic and proliferative actions of SCF. Our results indicate that the response to SCF mediated by c-kit may be involved in growth, migration, and metastatic ability of Ewing's sarcoma cells.