C-kit Overexpression Research Articles

Immunohistochemical and Mutational Analysis of c-kit in Gastrointestinal Neuroendocrine Cell Carcinoma

Gastrointestinal neuroendocrine cell carcinoma (NEC) is a highly aggressive tumor with poor prognosis, for which an effective therapy is highly desirable. Recently, use of a c-kit inhibitor achieved excellent results against gastrointestinal stromal tumor (GIST) that showed c-kit overexpression and mutation in most cases. According to recent studies, 17-44% of pulmonary NEC also expressed c-kit and the antitumor effect of c-kit inhibitor was demonstrated in vitro against small cell carcinoma of the lung. As gastrointestinal NECs are clinicopathologically similar to pulmonary NECs, we investigated c-kit expression and mutation in gastrointestinal NEC. Surgically resected gastrointestinal NEC was examined for c-kit expression by immunohistochemistry and RT-PCR. Mutation of the c-kit gene was also investigated by means of single-strand conformation polymorphisms (SSCP). Twenty-six percent (6 out of 23 patients) of gastrointestinal NEC expressed c-kit protein. c-kit protein expression was demonstrated in 1 out of 4 colorectal, 1 out of 2 duodenal, 4 out of 16 gastric and no esophageal (sample size of 1) NECs. The results of immunohistochemistry for c-kit were consistent with the RT-PCR. No c-kit gene mutation was found in gastrointestinal NEC. The frequency of c-kit expression in gastrointestinal NEC was similar to that previously reported for pulmonary NEC. These findings suggest that c-kit inhibitor may be effective against some gastrointestinal NECs.

C-kit Overexpression in Chromophobe Renal Cell Carcinoma Is Not Associated With c-kit Mutation of Exons 9 and 11

c-kit Overexpression in Chromophobe Renal Cell Carcinoma Is Not Associated With c-kit Mutation of Exons 9 and 11

Haploinsufficiency of Runx1/AML1 promotes myeloid features and leukaemogenesis in BXH2 mice

Haploinsufficiency of RUNX1/AML1 is associated with familial platelet disorder with a predisposition to acute myeloid leukaemia (FPD/AML), but the causal relationship remains to be addressed experimentally. Mice heterozygous for the Runx1 null mutation, Runx1+/-, are considered to be genetically comparable with human FPD/AML patients but do not develop spontaneous leukaemia. To induce additional genetic alterations, retroviral insertional mutagenesis was employed with the use of BXH2 mice, which develop myeloid leukaemia because of the random integration of retrovirus present in the mouse. Heterozygous disruption of Runx1 in BXH2 mice resulted in a shortening of the latency period of leukaemia. In addition, BXH2-Runx1+/- mice exhibited more marked myeloid features than control mice. Moreover, the c-Kit gene, mutated in human RUNX leukaemias, was recurrently activated in BXH2-Runx1+/- mice, and a colony-forming assay revealed synergism between the Runx1+/- status and c-KIT overexpression. In conclusion, the BXH2-Runx1+/- system is a promising mouse model to investigate the mechanism of leukaemogenesis in FPD/AML.

C-kit Overexpression in Chromophobe Renal Cell Carcinoma Is Not Associated With c-kit Mutation of Exons 9 and 11

c-kit Overexpression in Chromophobe Renal Cell Carcinoma Is Not Associated With c-kit Mutation of Exons 9 and 11

A phase II NCCTG/CALGB trial of imatinib (STI571) in patients (pts) with c-kit-expressing relapsed small cell lung cancer (SCLC)

7048 Background c-Kit over-expression is found in multiple cancers including up to 70% of SCLC. STI571 can inhibit c-kit tyrosine kinase activity and has high efficacy in chemoresistant c-kit positive (c-kit+) gastrointestinal stromal tumors. A phase II study of STI571 in unselected SCLC pts by Johnson et al., was negative, but inconclusive for proof- of - principle purposes, since 80% of tumors did not express c-kit. We therefore sought to evaluate clinical activity of STI571 in the treatment of patients with recurrent and refractory c-kit+ SCLC. Methods Only c-kit+ SCLC cases were enrolled on this study (≥ 1+ by immunohistochemistry). Arm A included pts progressing < 3 months and Arm B included pts progressing ≥ 3 months after previous treatment. STI571 was administered at a dose of 400 mg bid continuously, with a cycle length of 28 days. A single stage Simon design with a planned interim analysis was used to evaluate the 16 week progression free rate in each arm. Results A total of 29 evaluable pts were entered into the study (7 arm A, median age 68; 22 arm B, median age 65). Median number of treatment cycles was 1 in both arms. All pts are now off active treatment. Grade3+ non-hematologic adverse events were seen in 15(52%) pts, with nausea, vomiting, dyspnea, fatigue, anorexia and dehydration occurring in at least 10% of pts. Median survival was 3.9 and 5.3 months and median time to progression was 1 and 1.1 month for arms A and B, respectively. Enrollment to arm A was temporarily suspended prior to reaching interim analysis due to progression (29%), early deaths (29%), and refusal (42%). No objective responses and no confirmed stable disease ≥ 6 weeks were seen in either arm. Accrual was permanently terminated to both arms as no patient was progression-free at 16 weeks. Conclusion STI571 was inactive in spite of pt selection for c-kit+ SCLC. Our results strengthen the collective evidence that prediction of efficacy of novel therapeutic agents based on target expression, rather than pathway activation (for example through activating mutations), may not be a valid paradigm for drug development. No significant financial relationships to disclose.

Analysis of the clinical implications of c-kit expression in small cell lung cancer patients (SCLC)

7164 Background: c-kit is a growth factor receptor that plays a crucial role in the biology of cancer. The aim of this study was to determine the incidence and role of c-kit overexpression as a prognostic marker in patients with SCLC. Methods: A retrospective study with 70 patients diagnosed of SCLC was performed. Relevant clinical information was obtained from chart review (age, performance status -PS-, weight loss, tumor stage and response to therapy). c-kit expression was analyzed in formalin-fixed and paraffin-embedded tumor tissues immunohistochemically. Results: Mean age of the cohort was 62.5 years [40–80] and 96% were males. 35 patients presented extended disease (ED) at diagnosis and 35 patients limited disease (LD). c-kit expression was observed in 58.7% of the patients. c-kit was observed in 44.4% in LD and 55.6% in ED (p=0.402). All patients were former o actual smokers. Weight loss was present in 52.3% at diagnosis. Patients with a PS between 0–2 represented 85.7% of the c-kit positive group and 90% in the c-kit negative one. 36 patients received a median of 4 cycles of first-line therapy (52.2% vs 47.8% in c-kit positive and negative group respectively). The most used schedule was platinum plus etoposide and the most common second-line agent was topotecan. Radiotherapy of the primary tumor was administered in 42.9% of the patients in the c-kit positive group and in 30% in the negative one (p=0.107). In LD and comparing the c-kit positive group vs the negative one: Complete Response (CR) and Partial Response (PR) was observed in 75% versus 60%.and Stable Disease (SD) or Progressive Disease (PD) in 25% vs 40%, (p=384). Mean time to progression (TTP) was 11.7 vs 5.9 months respectively (p=0.26) and overall survival (OS) was 24.5 vs 17.5 months (p=0.17). In the EE group CR +PR was observed in 40% vs 33% and SD + PD in 60% vs 67%, (p=547). TTP was 5.9 vs 8.9 months respectively (p=0.72) and OS was 5.9 vs 11.8 months (p=0.65). Conclusions: c-kit is expressed in about 60% of the patients with SCLC. Our findings do not suggest a significant association between c-kit expression and survival either in the ED or LD group. New studies with longer cohorts are needed in order to define its prognostic value. No significant financial relationships to disclose.

Therapy, outcome and analysis of c-kit expression in patients with extrapulmonary small cell carcinoma

In this study, we aimed to investigate the clinicopathological characteristics with special emphasis on c-kit expression and the treatment results of patients with extrapulmonary small cell carcinoma (EPSCC). The medical records of the patients with EPSCC were reviewed, and the data regarding patient and tumour characteristics, treatment and clinical outcome were retrieved and analysed. A total of 28 patients with the diagnosis of EPSCC were identified. There were 19 males and 9 females, with a mean age of 56.5 years. Patients with limited disease (LD) (n = 13) were treated with surgery, chemotherapy (CT) and radiotherapy with different sequences. Patients with extensive disease (ED) (n = 15) were mainly treated with combination CT. The median overall survival was 14.5 months in patients with LD compared to 11 months in those with ED (p = 0.029). Ten patients (36%) showed c-kit overexpression. There was no significant difference between the survival of c-kit-positive and c-kit-negative patients (p = 0.367). In conclusion, our study demonstrates that the prognosis of EPSCC is poor despite currently available treatments. C-kit may be considered as a potential target for novel therapeutical approaches.

Prognostic Significance of Allelic Imbalance at the c-kit Gene Locus and c-kit Overexpression by Immunohistochemistry in Pediatric Osteosarcomas

Since the recent development of biologic agents targeting oncogenes, increasing attention has been focused on determining the role of tyrosine kinase receptors in the pathogenesis of tumors. Our study was designed to investigate the status of region 4q12, which contains the candidate gene c-kit, and the expression of c-kit by immunohistochemistry (IHC). Paired blood and biopsy specimens of 68 children treated for high-grade primary osteosarcomas were collected. Microsatellite analysis at two genomic sites containing c-kit gene was performed on paired DNA using a sensible fluorescent polymerase chain reaction technology. To confirm the DNA data, we studied c-kit protein expression by IHC in 56 available paraffin-embedded tumor tissues. The frequency of allelic imbalance (AI) at locus 4q12 was 39% in the overall population. In agreement with previous studies, we did not detect microsatellite instability, allowing us to hypothesize that this pathway is not implicated. Furthermore, the normal status at locus 4q12 was associated with a significantly better survival in the whole osteosarcoma population (P = .05). IHC overexpression of c-kit was concordant in all cases presenting an AI. However, normal status at locus 4q12 was correlated to an absence of c-kit protein expression in 19 (65.5%) of 29 informative cases. Allelotyping of locus 4q12, which contains the c-kit gene, could help pediatric osteosarcoma prognostic screening and showed a strong correlation with overexpression of c-kit protein. These results allowed us to hypothesize that, in some cases, a mutation of c-kit gene could lead to a protein overexpression.

Imatinib Mesylate in Patients With Adenoid Cystic Cancers of the Salivary Glands Expressing c-kit: A Princess Margaret Hospital Phase II Consortium Study

This study aimed to assess the antitumor activity of imatinib in adenoid cystic carcinoma (ACC) of the salivary gland expressing c-kit. A high level of c-kit expression has been identified in more than 90% of ACCs. Imatinib specifically inhibits autophosphorylation of the bcr-abl, platelet-derived growth factor receptor beta, and c-kit tyrosine kinases. In a single-arm, two-stage, phase II clinical trial, adult patients with unresectable or metastatic ACC measurable by Response Evaluation Criteria in Solid Tumors Group criteria and expressing c-kit by immunohistochemistry were treated with imatinib 400 mg orally bid. Response was assessed every 8 weeks. Sixteen patients have been enrolled onto the study; 10 were female. Median age was 47 years (range, 31 to 69 years). Median Eastern Cooperative Oncology Group performance status was 1 (range, 0 to 2). Fourteen patients had lung metastases, 14 had prior radiotherapy, and six had prior chemotherapy. Toxicities occurring in at least 50% of patients included fatigue, nausea, vomiting, diarrhea, anorexia, edema, dyspnea, and/or headache, usually of mild to moderate severity. In 15 patients assessable for response, no objective responses have been observed. Nine patients had stable disease as best response. Six patients had progressive disease after two cycles. Because of the lack of activity, the study has been stopped after the first stage and additional evaluation of imatinib in this population is not warranted. Overexpression of wild-type c-kit was not sufficient for clinical benefit from imatinib in ACC. Accrual to this study was rapid for a relatively rare cancer, encouraging additional efforts to identify more effective systemic therapy for these patients.

HER-2/neu and CD117 (c-kit) overexpression in patients with pesticide exposure and extensive stage small cell lung carcinoma (ESSCLC)

BackgroundThe rate of detection of HER-2/neu and CD117 (c-kit) overexpression in small cell lung cancer (SCLC) has varied widely; between 5–35% and 21–70% respectively.MethodsTo evaluate the relationship between pesticide exposure and HER-2/neu and CD117 overexpression in extensive stage SCLC (ESSCLC), we identified patients with ESSCLC and assessed pesticide exposure using a predetermined questionnaire. An exposure index (hours/day × days/year × years) ≥ 2400 hours was considered as 'exposed.' HER-2/neu overexpression was evaluated on archival tissue using the DAKO Hercep test, and CD117 testing was performed using immunohistochemistry (A4052 polyclonal antibody).Results193 ESSCLC patients were identified. Pesticide exposure data could be obtained on 174 patients (84 females and 109 males) with a mean age of 68.5 years. 53/174 (30.4%) revealed HER-2/neu overexpression. 54/174 (31.03%) specimens showed CD117 overexpression by IHC. On multivariate analysis, HER-2/neu overexpression was associated with diminished survival (p < 0.001). In comparison, CD117 expression did not have an adverse prognostic value (p = 0.025). 41/53 (77.4%) patients with HER-2/neu overexpression and 47/121 (38.8%) patients without overexpression had exposure to pesticides (odds ratio: 5.38; p < 0.01). Among the cohort tested for CD117, 29/54 (53.7%) patients with CD117 overexpression and 59/120 (49.2%) patients without CD117 overexpression had pesticide exposure (odds ratio: 1.18; p = 0.12).ConclusionPesticide exposure affects HER-2/neu but not CD117 overexpression. Future studies are needed to determine specific pesticide(s)/pesticide components that are responsible for HER-2/neu overexpression in ESSCLC, and to validate our findings in other solid tumors that overexpress HER-2/neu.

High Frequency Gain-of-Function Mutation and/or Over-Expression of Proto-Oncogene C-KIT as Major Contributor to the Leukemogenesis in Human Acute Myeloid Leukemia with t(8; 21).

To explore the genetic abnormalities that cooperate with AML1-ETO (AE) fusion gene in the pathogenesis of acute myeloid leukemia (AML) with t(8; 21), we undertook to screen for a number of candidate genes and identified a high frequency mutation of proto-oncogene C-KIT (25/53 cases, 47%). This event seems to be specific to t(8;21) leukemia since no mutation was detected in 57 patients with other types of leukemia. Totally eleven types of mutations were characterized and 6 ones including 3 point mutations in the tyrosine kinase (TK) domain and three types of internal tandem duplication (ITD) in the juxtamembrane (JM) or extracellular (EC) domains were discovered for the first time. Bioinformatics analysis revealed all these mutations might favor the activation of the C-KIT, as proven by TK activity assay. Patients with a mutant C-KIT (mC-KIT) allele had a higher white blood cell count and a poorer prognosis than those bearing wild-type C-KIT. The expression of C-KIT at both mRNA and protein levels was higher in t(8;21) leukemia patients than most other leukemia types. In addition, the TK inhibitor Gleevec suppressed the C-KIT activity, inhibited the proliferation and induced apoptosis of t(8;21) leukemic cells bearing C-KIT mutation or over-expression. Our study thus provides strong evidence to the model of leukemogenesis which requires a cooperation of cytosolic signaling and transcription factor for a full-blown leukemia phenotype to display.

Clinical features at presentation, C-kit, and Her2/neu overexpression as prognostic factors in elderly patients with lung carcinoma

9636 Purpose: To determine the clinical predictors of survival and significance of C-kit and Her2/neu overexpression as prognostic markers in elderly males (age =/>65 years) with lung carcinoma (LC). Methods: After approval from the institutional review board, a retrospective chart review was performed to obtain demographic/clinical data on elderly males with a biopsy-proven LC. C-kit and Her2/neu overexpression was also assessed using immunohistochemical techniques (IHC). Results: 64 elderly males (mean age: 73.75 years; range: 65–87 years) were included in our study. 12/64 patients (18.75%) had small cell lung cancer (SCLC) and 48 (75%) had non-small cell lung cancer (NSCLC). 4 patients (6.25%) refused diagnostic biopsies. The most common diagnostic procedures were CT-guided biopsy (n=38, 59.37%) and transbronchial biopsy (n=12, 18.75%). Of the 64 patients studied, 24 (37.5%) presented with cough, 16 (25%) as an incidental finding and 8 (12.5%) with dyspnea. Cox regression analysis revealed that patients with dyspnea at presentation had a 4.25 greater odds (95% CI 1.8–10, p=0.01) of early demise as compared with cough. With increasing performance status (from ECOG 0 to 4), the hazards of dying increased by 1.27 times the previous level (p=0.005). Interestingly, of the 12 patients with SCLC, 4 (33.3%) revealed C-kit overexpression, while none of the NSCLC specimens revealed overexpression. Also, after adjusting for confounding variables, C-kit overexpression was associated with a significant survival advantage (p=0.018) in SCLC, using the Log rank test. In contrast, presence of Her2/neu identified in 4 patients with SCLC (33.3%) and 9 NSCLC patients (18.75%) had an insignificant effect on survival (p=0.87) in elderly males with LC. Conclusions: Elderly males with LC represent a select subgroup with characteristic clinical and pathologic features. Her2/neu overexpression seen in NSCLC and SCLC lacks prognostic significance in elderly males. Interestingly, however, c-kit overexpression, seen in ∼30% of the SCLC cohort seems to confer a survival advantage. Further larger studies are needed to validate our findings. No significant financial relationships to disclose.

Clinical features at presentation, C-kit, and Her2/neu overexpression as prognostic factors in elderly patients with lung carcinoma

9636 Purpose: To determine the clinical predictors of survival and significance of C-kit and Her2/neu overexpression as prognostic markers in elderly males (age =/>65 years) with lung carcinoma (LC). Methods: After approval from the institutional review board, a retrospective chart review was performed to obtain demographic/clinical data on elderly males with a biopsy-proven LC. C-kit and Her2/neu overexpression was also assessed using immunohistochemical techniques (IHC). Results: 64 elderly males (mean age: 73.75 years; range: 65–87 years) were included in our study. 12/64 patients (18.75%) had small cell lung cancer (SCLC) and 48 (75%) had non-small cell lung cancer (NSCLC). 4 patients (6.25%) refused diagnostic biopsies. The most common diagnostic procedures were CT-guided biopsy (n=38, 59.37%) and transbronchial biopsy (n=12, 18.75%). Of the 64 patients studied, 24 (37.5%) presented with cough, 16 (25%) as an incidental finding and 8 (12.5%) with dyspnea. Cox regression analysis revealed that patients with dyspnea at presentation had a 4.25 greater odds (95% CI 1.8–10, p=0.01) of early demise as compared with cough. With increasing performance status (from ECOG 0 to 4), the hazards of dying increased by 1.27 times the previous level (p=0.005). Interestingly, of the 12 patients with SCLC, 4 (33.3%) revealed C-kit overexpression, while none of the NSCLC specimens revealed overexpression. Also, after adjusting for confounding variables, C-kit overexpression was associated with a significant survival advantage (p=0.018) in SCLC, using the Log rank test. In contrast, presence of Her2/neu identified in 4 patients with SCLC (33.3%) and 9 NSCLC patients (18.75%) had an insignificant effect on survival (p=0.87) in elderly males with LC. Conclusions: Elderly males with LC represent a select subgroup with characteristic clinical and pathologic features. Her2/neu overexpression seen in NSCLC and SCLC lacks prognostic significance in elderly males. Interestingly, however, c-kit overexpression, seen in ∼30% of the SCLC cohort seems to confer a survival advantage. Further larger studies are needed to validate our findings. No significant financial relationships to disclose.

Functional and molecular profiling of heterogeneous tumor samples using a novel cellular microarray

9507 Background: Current standards in pathological diagnosis are based on tissue of origin, microscopic examination, immunohistochemistry and immunophenotyping. This leads to a most likely diagnosis utilizing minimal acceptable resources, ignoring potentially important information based upon likelihood of occurrence. Methods: We have developed a novel method for analyzing heterogeneous clinical samples utilizing a cellular microarray to profile both cell molecular composition and cellular function in a rapid fashion. By co-spotting mixtures of a) capture probes, which recognize cell surface molecules, b) detection probes, which recognize molecules secreted by cells and c) effector probes, which can signal a change in cell behavior, in a microarray format, cells can be specifically captured and analyzed for their molecular and behavioral patterns. Results: Blood, lymph nodes and surgical biopsies from patients with malignancies were dissociated into single cell suspensions and applied to the cellular microarray. Diagnosis of the tumor type was obtained by analysis of a molecular profile. Benign and malignant cells were distinguishable by differences in their microscopic appearance, glucose metabolism, and their metabolic capacity. Functional profiling of secreted factors such as vascular endothelial growth factor (VEGF), matrix metalloproteinases (MMPS), provided a specific molecular signature. The cellular microarray also determined the presence of unexpected therapeutic targets, such as overexpression of c-kit, on the surface of tumor cells from some of the clinical samples. Conclusions: The use of cellular microarrays provides a versatile, simple and rapid platform for profiling molecular and functional patterns in single cells. This information is correlated to clinical disease, and may provide improved ability to determine best treatment, identification of unexpected therapeutic options, and provide more accurate prognosis. This technology may be applied to routine clinical laboratory analysis and lead to the development of functional pathology using viable cellular samples. No significant financial relationships to disclose.

Effect of pesticide exposure on HER-2/neu and CD117 overexpression in patients with extensive stage small cell lung carcinoma (ESSCLC)

9629A Background: In previous reports, the rate of detection of HER-2/neu and CD117 (c-KIT) overexpression in SCLC has varied widely; between 5–35% and 21–70% respectively. Methods: To evaluate the relationship, if any, between pesticide exposure and overexpression of HER-2/neu and CD117 in extensive stage small cell lung cancer (ESSCLC), we identified patients with ESSCLC and assessed pesticide (herbicide and insecticide) risk by personal interviews using a predetermined questionnaire. An exposure index (hours/day × days/year × years) ≥ 2400 hours was considered as ‘exposed.’ HER-2/neu overexpression was evaluated on archival tissue using the DAKO Hercep test, and CD117 testing was performed using immunohistochemistry (A4052 polyclonal antibody). Results: 193 ESSCLC patients were identified during the study period. Pesticide exposure data could be obtained on 174 patients (84 females and 109 males) with a mean age of 68.5 years. 53/174 (30.4%) revealed HER-2/neu overexpression. Similarly, 54/174 (31.03%) specimens showed CD117 overexpression by IHC. On multivariate analysis, HER-2/neu overexpression was associated with diminished survival (p < 0.001). In comparison, CD117 expression did not have prognostic value (p = 0.025) in our study population. 41/53 (77.4%) patients with HER-2/neu overexpression and 47/121 patients without overexpression (38.8%) were exposed to pesticides. Interestingly, patients with a history of pesticide exposure had a higher risk of having HER-2/neu overexpression (odds ratio: 5.38; p < 0.01, 95% CI: 2.5–11.2). Among the cohort tested for CD117, 29/54 (53.7%) patients with CD117 overexpression and 59/120 (49.2%) patients without CD117 overexpression had evidence of pesticide exposure (odds ratio: 1.18; p = 0.12). Conclusions: Pesticide exposure seems to affect HER-2/neu overexpression but does not seem to be associated with overexpression of CD117. Future studies are needed to determine specific pesticide(s)/pesticide components that are responsible for HER-2/neu overexpression seen in ESSCLC, and to validate our findings in other solid tumors that overexpress HER-2/neu.

Effect of pesticide exposure on HER-2/neu and CD117 overexpression in patients with extensive stage small cell lung carcinoma (ESSCLC)

9629A Background: In previous reports, the rate of detection of HER-2/neu and CD117 (c-KIT) overexpression in SCLC has varied widely; between 5–35% and 21–70% respectively. Methods: To evaluate the relationship, if any, between pesticide exposure and overexpression of HER-2/neu and CD117 in extensive stage small cell lung cancer (ESSCLC), we identified patients with ESSCLC and assessed pesticide (herbicide and insecticide) risk by personal interviews using a predetermined questionnaire. An exposure index (hours/day × days/year × years) ≥ 2400 hours was considered as ‘exposed.’ HER-2/neu overexpression was evaluated on archival tissue using the DAKO Hercep test, and CD117 testing was performed using immunohistochemistry (A4052 polyclonal antibody). Results: 193 ESSCLC patients were identified during the study period. Pesticide exposure data could be obtained on 174 patients (84 females and 109 males) with a mean age of 68.5 years. 53/174 (30.4%) revealed HER-2/neu overexpression. Similarly, 54/174 (31.03%)...

Expression of the proto-oncogene c-KIT in normal and tumor tissues from colorectal carcinoma patients.

The proto-oncogene c-KIT encodes a tyrosine kinase receptor essential during embryonic development and postnatal life. Although deregulated expression of c-KIT has been reported, its role in colorectal carcinoma remains controversial: some authors have described a correlation between c-KIT expression and colorectal cancer (CRC), while others have failed to detect the receptor in the majority of neoplasia examined. To address this question, we designed a prospective study to analyze the expression of c-KIT in normal and neoplastic colonic mucosa of the same patient. We analyzed the tissues of 20 patients undergoing surgical resection for colorectal carcinoma by reverse transcriptase-polymerase chain reaction, Western blot and immunohistochemistry, whose results were correlated with histopathological parameters. Most patients (90%) showed c-KIT expression in normal tissue both at RNA and protein level, while in neoplastic tissue it was observed in 30% of patients at RNA level and in 10% at protein level. By immunohistochemistry the localization of c-KIT protein in the normal colon was restricted to interstitial cells scattered in the stroma, whereas the non-neoplastic epithelium was always negative. The mucinous carcinomas were all c-KIT negative, whereas the only case in which c-KIT was displayed in the neoplastic epithelium was a G3 adenocarcinoma. Most colorectal carcinomas do not express c-KIT. We suggest that c-KIT expression is rarely present in this neoplasia; thus, the use of receptor inhibitors should be conducted in selected sub-groups of colon carcinoma patients, subsequent to the clear demonstration of c-KIT overexpression in the neoplastic cells.

C-KIT expression and correlation with chemotherapy resistance in ovarian carcinoma: an immunocytochemical study

BackgroundRecent studies have shown that several tumours express c-KIT, a growth factor receptor with tyrosine kinase activity; moreover, clinical results have shown the efficacy of the tyrosine kinase inhibitor, STI571, in c-KIT-positive tumours. The aim of this study was to determine the incidence and correlation with chemotherapy resistance of c-KIT expression in advanced serous, low grade of differentiation, ovarian carcinoma. Patients and methodsWe performed an immunohistochemistry analysis of 56 patients with advanced serous ovarian carcinomas using archival paraffin-embedded specimens. ResultsIntense c-KIT immunostaining was observed in 51.7% of cases. c-KIT expression was statistically correlated with progression of disease after first-line chemotherapy (P = 0.029). Conclusionsc-KIT is also expressed in ovarian carcinoma and it is statistically correlated with chemotherapy resistance. This study suggests the necessity for clinical trials confirming the utility of the tyrosine kinase inhibitor, STI571, in ovarian advanced cancer patients with c-KIT overexpression when these patients have shown no clinical response to conventional chemotherapy.

Phosphorylation status of c-Kit and Epo receptors, and the presence of wild-type p53 confer in vitro resistance of murine erythroleukemic cells to Celecoxib.

It is well established that selective COX-2 inhibitors exhibit potent effects against progression of select solid tumours. However, their effects on liquid tumours have not been fully established. By taking advantage of murine Friend Disease we have shown a strong antileukemic effect of celecoxib by determining novel in vitro targets. Western blot analyses revealed the expression of COX-2 in a panel of Friend Virus-transformed, splenic-derived primary erythroleukemic blasts and established cell lines generated in our laboratory. We have shown that celecoxib at concentrations as low as 20 microM significantly suppresses proliferation of the selected murine erythroleukemia cell line HB60-5. The greatest proliferative inhibition was seen at 40 microM of celecoxib, resulting in apoptosis. Our results also demonstrate that treatment of the established murine erythroleukemia cell line HB60-5 with celecoxib results in suppression of c-Kit and erythropoietin receptor (Epo-R) phosphorylation resulting in apoptosis, likely through decreased levels of survival factors. However, upon overexpression of c-Kit alone in these cells a significant increase in survival and twofold increase in proliferation in the presence of celecoxib were observed (P < 0.05). Finally, since responsiveness of our murine erythroleukemia cell lines to celecoxib is above the reported physiologically achievable levels in vivo, we have provided in vitro evidence to suggest that reduced sensitivity of erythroleukemic cells to lower doses of celecoxib may be a consequence of the loss of wild-type p53. These findings are pivotal in addressing potential discrepancies associated with sensitivity of murine erythroleukemic cells to celecoxib in vitro versus in vivo.

Expression of HER2 and C-KIT in Nasopharyngeal Carcinoma: Implications for a New Therapeutic Approach

We sought to determine the expression and prognostic significance of HER2 and c-KIT proteins in nasopharyngeal carcinoma (NPC). In this retrospective study, immunohistochemical stains for HER2 and c-KIT were performed on formalin-fixed paraffin-embedded sections from 49 patients with NPC who were treated at our hospital from 1971 to 2000. The clinical and immunohistochemical data were correlated, including gender, ethnic origin, age, histological type, EBV status (EBER in situ hybridization), stage, and overall survival. HER2 expression was not found in the tested samples. C-KIT overexpression was found in 33% (16/49) of the patients. Nine of the 16 samples (56%) were strongly positive for c-KIT protein (staining of >50% of the tumor cells). C-KIT expression was associated with younger age. C-KIT was not found in patients with squamous carcinoma or in those with negative EBV status, although these two groups consisted of only five patients each. Although c-KIT–positive cases tended to be associated with slightly better survival, this was not statistically significant. C-KIT protein was expressed in one third of the NPC patients in this study, only in EBV-positive, undifferentiated, or nonkeratinizing carcinoma patients. Further study is needed to check whether c-KIT expression is correlated with c-KIT DNA mutations and to test the possibility of treatment with imatinib mesylate (Gleevec). HER2 protein was negative in the same tested specimens.