Immunohistochemical expression of receptor-tyrosine kinase c-kit protein in invasive ductal carcinoma of the pancreas

Desmoplastic Adamantinoma-like Thymic Carcinoma: Clinicopathologic, Immunohistochemical, and Molecular Study of 5 Cases

Five cases of a heretofore unreported rare variant of thymic carcinoma characterized by a striking resemblance to adamantinoma of the mandible are described. The tumors occurred in 4 women and 1 man aged 58 to 76 years (mean: 67.8 y); they arose in the anterior mediastinum and measured from 5.3 to 12.0 cm in greatest diameter (mean: 8.9 cm). Presenting symptoms included chest pain, shortness of breath, and in 2 patients, pleural effusion. One tumor was asymptomatic and discovered incidentally. Histologically, the tumors were extensively desmoplastic, and the cellular proliferation was characterized by multiple islands of squamous epithelium with striking peripheral palisading of nuclei and central areas containing clear cells resembling a stellate reticulum. Areas of preexisting spindle cell thymoma were identified in 2 cases; these areas gradually merged with the higher-grade component of the lesion. Cystic changes were noted in 3 cases. Immunohistochemical studies in 3 cases showed the tumor cells were positive for cytokeratins, p40 and p63, and all showed a high proliferation rate (>50% nuclear positivity) with Ki-67. Next-generation sequencing was performed in 2 cases that showed amplification of the AKT1 gene (copy numbers 6 and 13). Clinical follow-up in 3 patients showed recurrence and metastasis after 1 and 2 years; 1 patient passed away 2 years after diagnosis due to the tumor. Desmoplastic adamantinoma-like thymic carcinoma represents an unusual histologic variant of thymic carcinoma that needs to be distinguished from metastases from similar tumors to the mediastinum.

Immunohistochemical study of C-kit expression in subtypes of renal cell carcinoma

Objective

Renal cell carcinomas (RCCs) include about 2% of adult neoplasms and 90-95% of all renal tumors. Mostly, it is possible to distinguish RCC subtypes using hematoxylin-eosin staining. However, overlapping morphologic features cause some difficulties in making a precise diagnosis. In order to render an accurate diagnosis, additional methods such as immunohistochemical staining for c-kit have been recommended. In this study, we aimed to investigate c-kit gene expression in various subtypes of RCC.

Material and methods

We reviewed 65 diagnosed RCC cases. Formalin- fixed, paraffin- embedded specimens were available for the cases. The expression of c-kit was evaluated using immunohistochemistry. The correlation between c-kit expression and clinicopathological parameters including patients' age and gender in addition to grade, stage, and size of the tumor were investigated.

Results

Six cases of 39 clear cell types (15.4%), 8 of 13 papillary types (61.5%), 11 of 12 chromophobe types (91.7%), and no sarcomatoid type were positive for c-kit expression. Based on chi-square test results, there was a significant relationship between RCC subtypes and c-kit expression (p=0.001). There was no significant correlation between age, sex, grade, stage, and size of the tumor and c-kit expression.

Conclusion

The expression of c-kit in RCC may have diagnostic significance in subtypes of RCC especially papillary and chromophobe subtypes of RCC.

Resistance to the tyrosine kinase inhibitor axitinib is associated with increased glucose metabolism in pancreatic adenocarcinoma

Alterations in energy (glucose) metabolism are key events in the development and progression of cancer. In pancreatic adenocarcinoma (PDAC) cells, we investigated changes in glucose metabolism induced by resistance to the receptor tyrosine kinase inhibitor (RTKI) axitinib. Here, we show that human cell lines and mouse PDAC cell lines obtained from the spontaneous pancreatic cancer mouse model (Kras(G12D)Pdx1-cre) were sensitive to axitinib. The anti-proliferative effect was due to a G2/M block resulting in loss of 70-75% cell viability in the most sensitive PDAC cell line. However, a surviving sub-population showed a 2- to 3-fold increase in [C-14]deoxyglucose ([C-14]DG) uptake. This was sustained in axitinib-resistant cell lines, which were derived from parental PDAC. In addition to the axitinib-induced increase in [C-14]DG uptake, we observed a translocation of glucose transporter-1 (Glut-1) transporters from cytosolic pools to the cell surface membrane and a 2-fold increase in glycolysis rates measured by the extracellular acidification rate (ECAR). We demonstrated an axitinib-induced increase in phosphorylated Protein Kinase B (pAkt) and by blocking pAkt with a phosphatidylinositol-3 kinase (PI3K) inhibitor we reversed the Glut-1 translocation and restored sensitivity to axitinib treatment. Combination treatment with both axitinib and Akt inhibitor in parental pancreatic cell line resulted in a decrease in cell viability beyond that conferred by single therapy alone. Our study shows that PDAC resistance to axitinib results in increased glucose metabolism mediated by activated Akt. Combining axitinib and an Akt inhibitor may improve treatment in PDAC.

Maintenance sunitinib or observation in metastatic pancreatic adenocarcinoma: a phase II randomised trial

BACKGROUND

New strategies to prolong disease control warrant investigation in patients with metastatic pancreatic adenocarcinoma. This open-label, randomised, multi-centre phase II trial explored the role of maintenance sunitinib after first-line chemotherapy in this setting.

METHODS

Patients with pathologic diagnosis of metastatic pancreatic adenocarcinoma, performance status >50%, no progression after 6 months of chemotherapy were centrally randomised by an independent contract research organisation, which was also responsible for data collection and monitoring, to observation (arm A) or sunitinib at 37.5mg daily until progression or a maximum of 6 months (arm B). The primary outcome measure was the probability of being progression-free at 6 months (PFS-6) from randomisation. Assuming P0 = 10%; P1 = 30%, α .10; β .10, the target accrual was 26 patients per arm.

RESULTS

28 per arm were randomised. One arm B patient had kidney cancer and was excluded. Sunitinib was given for a median of 91 days (7-186). Main grade 3-4 toxicity was thrombocytopenia, neutropenia and hand-foot syndrome (12%), diarrhoea 8%. In arm A versus B, PFS-6 was 3.6% (95% confidence interval (CI): 0-10.6%) and 22.2% (95% CI: 6.2-38.2%; P<0.01); 2 y overall survival was 7.1% (95% CI: 0-16.8%) and 22.9% (95% CI: 5.8-40.0%; P = 0.11), stable disease 21.4% and 51.9% (P = 0.02).

CONCLUSION

This is the first randomised trial on maintenance therapy in metastatic pancreatic adenocarcinoma. The primary end-point was fulfilled and 2 y overall survival was remarkably high, suggesting that maintenance sunitinib is promising and should be further explored in this patient population.

Activation of PDGFr-β Signaling Pathway after Imatinib and Radioimmunotherapy Treatment in Experimental Pancreatic Cancer

Pancreatic cancer does not respond to a single-agent imatinib therapy. Consequently, multimodality treatments are contemplated. Published data indicate that in colorectal cancer, imatinib and radioimmunotherapy synergize to delay tumor growth. In pancreatic cancer, the tumor response is additive. This disparity of outcomes merited further studies because interactions between these modalities depend on the imatinib-induced reduction of the tumor interstitial fluid pressure. The examination of human and murine PDGFr-β/PDGF-B pathways in SW1990 pancreatic cancer xenografts revealed that the human branch is practically dormant in untreated tumors but the insult on the stromal component produces massive responses of human cancer cells. Inhibition of the stromal PDGFr-β with imatinib activates human PDGFr-β/PDGF-B signaling loop, silent in untreated xenografts, via an apparent paracrine rescue pathway. Responses are treatment-and time-dependent. Soon after treatment, levels of human PDGFr-β, compared to untreated tumors, are 3.4×, 12.4×, and 5.7× higher in imatinib-, radioimmunotherapy + imatinib-, and radioimmunotherapy-treated tumors, respectively. A continuous 14-day irradiation of imatinib-treated xenografts reduces levels of PDGFr-β and phosphorylated PDGFr-β by 5.3× and 4×, compared to earlier times. Human PDGF-B is upregulated suggesting that the survival signaling via the autocrine pathway is also triggered after stromal injury. These findings indicate that therapies targeting pancreatic cancer stromal components may have unintended mitogenic effects and that these effects can be reversed when imatinib is used in conjunction with radioimmunotherapy.

Expression of L1CAM, COX-2, EGFR, c-KIT and Her2/neu in anaplastic pancreatic cancer: putative therapeutic targets?

AIMS

Undifferentiated (anaplastic) pancreatic cancer and undifferentiated pancreatic carcinoma with osteoclast-like giant cells (giant cell tumour) are rare variants of pancreatic ductal adenocarcinoma. Representing biologically highly aggressive neoplasms, they are frequently diagnosed at an advanced stage. The response to established chemo- or radiochemotherapeutic treatment regimens is poor, and undifferentiated pancreatic cancer generally has a dismal prognosis. As additional therapeutic options have not yet been investigated in undifferentiated pancreatic cancer, the aim was to analyse the expression of putative therapeutic targets that have shown promising results in various other neoplasms.

METHODS AND RESULTS

Fifteen cases of undifferentiated pancreatic cancer (seven containing osteoclast-like giant cells) were investigated clinicopathologically and immunohistochemically for putative therapeutic targets. Whereas L1CAM, cyclooxygenase (COX)-2 and epidermal growth factor receptor (EGFR) were found to be significantly expressed in 80%, 93% and 87% of the investigated tumours, respectively, there was no substantial expression of c-kit (CD117) and there was no detectable expression of Her2/neu.

CONCLUSIONS

The expression of L1CAM, COX-2 and EGFR in the majority of undifferentiated pancreatic carcinomas suggests that they might represent targets for adjuvant therapy in anaplastic pancreatic cancer. On the other hand, c-kit and Her2/neu seem to have no relevance for the therapy of these tumours.

A phase II trial of imatinib mesylate in patients with metastatic pancreatic cancer

OBJECTIVES

The aim of the study was to assess the clinical efficacy and toxicity of single-agent imatinib mesylate in patients with advanced, unresectable metastatic pancreatic cancer.

METHODS

Previously treated or untreated patients with histologically proven, unresectable pancreatic adenocarcinoma with adequate organ and bone marrow function were enrolled. Patients received imatinib 400 mg orally twice a day for a 28-day cycle. Response was evaluated every 4 weeks by imaging scans. Response was defined as lack of tumor progression at 3 months.

RESULTS

Eleven patients were enrolled, and 9 were evaluable for response. Best response was stable disease in 3 patients after 2 cycles of therapy. All of them subsequently progressed. No patients remained on treatment for 3 months or longer, which was the response end point. Median time to tumor progression was 47 days (range, 19-76 days) and median overall survival was 118 days (range, 40-221 days). The first 3 patients received imatinib 400 mg orally twice a day. Due to unexpected grades 2 and 3 toxicities, the dose was reduced to 600 mg daily which was well tolerated. Most common adverse events included grades 1 to 2 edema, liver enzyme elevations, nausea, and rash.

CONCLUSION

Single-agent imatinib does not have a significant activity in pancreatic cancer.

MEK inhibitor enhances the inhibitory effect of imatinib on pancreatic cancer cell growth

Imatinib mesylate (imatinib) inhibits the c-Kit-dependent tyrosine kinase activities and highly effective in the treatment of CML and GIST patients. Although pancreatic cancer is reported to express c-Kit, imatinib does not effectively inhibit pancreatic cancer cell growth at physiological concentrations. Therefore, we investigated the mechanism of resistance of pancreatic cancer to imatinib treatment. Imatinib inhibited growth of pancreatic cancer cell lines in concentration and time-dependent fashion regardless of c-Kit expression. However, 5 microM imatinib, which is almost a mean maximal plasma concentration in clinical setting, failed to suppress pancreatic cancer cell growth. Western blot analysis demonstrated that 5 microM imatinib treatment for 1h activated the MEK-MAPK pathway and the activation was independent of Ras activation. Administration of 5 microM imatinib and 1 microM U0126 (MEK inhibitor) significantly suppressed pancreatic cell growth. Our results indicate that a combination therapy of imatinib and MEK inhibitor can be a new therapeutic strategy to suppress the progression of pancreatic cancer.

CD117 expression in normal, neoplastic, inflammatory, and reactive lesions of the thyroid

The mutations of c-kit gene, which encodes a transmembrane receptor tyrosine kinase (CD117-KIT) or activation of CD117, lead to the activation of signal transduction cascades regulating cell proliferation, apoptosis, chemotaxis, and adhesion. The aim of this study was to investigate the expression of CD117 in normal, inflammatory, neoplastic, and reactive lesions of the thyroid. Using polyclonal anti-CD117 antibody, we performed immunohistochemical staining on tissue blocks from 230 cases obtained from the archives of the Department of Pathology, Ondokuz Mayis University (Samsun, Turkey), collected between 1990 and 2006. Each slide was evaluated for extent and intensity of staining. Staining extent was expressed as the percentage of stained cells. Staining of <10% of the cells was accepted as negative. Staining intensity was evaluated only in positive cases. By addition of the extent and intensity scores, the combined score was calculated. In our study, the combined CD117 staining scores of neoplastic and inflammatory groups were found to be higher than the reactive and normal groups. Within the neoplastic group, papillary carcinomas differed from follicular adenomas significantly, although papillary carcinomas showed no statistically significant difference compared to follicular carcinomas. Immunohistochemical CD117 positivity was detected in a wide range of neoplastic and inflammatory thyroid diseases. The neoplastic group and, within them, the papillary carcinomas showed a higher ratio of CD117 positivity. Although our results need to be confirmed by other molecular and genetic studies, the high rate of positivity in papillary carcinomas was one of the striking findings, which may result in novel diagnostic and therapeutic approaches.

CD117/KIT expression in pancreatic adenocarcinoma

OBJECTIVE

CD117/KIT overexpression is common in neoplasms such as gastrointestinal stromal tumors and predicts clinical response to tyrosine kinase inhibitors. Pancreatic adenocarcinoma has a poor prognosis, and therefore, targeted molecular therapy may be beneficial. Marked differences in the incidence of CD117/KIT expression have been reported in pancreatic adenocarcinoma. The aim of this study was to test the hypothesis that CD117/KIT expression is unusual in pancreatic adenocarcinoma.

METHODS

CD117/KIT immunohistochemistry was performed on 23 archival pancreatic adenocarcinoma samples using 2 primary antibodies.

RESULTS

Satisfactory internal and external positive control labeling was achieved for both primary antibodies. No tumor cell labeling was identified using one primary antibody, whereas all cases showed cytoplasmic CD117/KIT staining with the second. However, CD117/KIT expression was also identified using the latter within nuclei and benign pancreatic epithelium, suggesting that artifactual staining was occurring.

CONCLUSIONS

Pancreatic adenocarcinoma does not express CD117/KIT as assessed using the primary immunohistochemical antibody usually used in our laboratory for CD117/KIT detection. The variation in reported incidence of CD117/KIT expression in pancreatic adenocarcinoma is because of methodological differences in immunohistochemical technique. Ideally, immunohistochemical studies of this molecule should be combined with mutational status testing of the c-kit gene.

Emerging role of platelet-derived growth factor receptor-beta inhibition in radioimmunotherapy of experimental pancreatic cancer

PURPOSE

Thus far, the therapy of pancreatic cancer remains an insurmountable challenge. Not a solitary therapeutic modality in the battery of available therapeutic options is capable to cure or, at the very least, stop the progression of this disease in any meaningful way. The purpose of reported here studies was to implement a multimodality approach to radioimmunotherapy of pancreatic cancer and, ultimately, to develop a course of therapy with the clinical value.

EXPERIMENTAL DESIGN

Animal model was NCr-nu/nu mouse bearing s.c. xenografts of SW1990 pancreatic adenocarcinoma. Radioimmunotherapy based on (131)ICC49, a TAG-72-targeting monoclonal antibody, was augmented with imatinib, a potent inhibitor of platelet-derived growth factor receptor-beta. The postulated interactions between these two modalities depended on the imatinib-induced drop in the tumor interstitial fluid pressure and the subsequent increase of (131)ICC49 uptake into the tumor, resulting in improved tumor responses to radioimmunotherapy.

RESULTS

Biodistribution studies revealed a 50% improvement in the tumor uptake of (131)ICC49 in mice treated with imatinib. Tumor development was practically arrested for approximately 3 weeks in response to the treatment composed of (131)ICC49 and imatinib with tumor quadrupling time (T(Q)) of 40.8 days. (131)ICC49 alone and imatinib alone also delayed the tumor growth to T(Q) of 30.2 and 31.2 days, respectively. Unanticipated was the significant response of SW1990 to a brief treatment with imatinib given i.p. at 100 mg/kg b.i.d. for 3 days. Xenografts in control mice receiving injection of PBS had T(Q) of 23 days.

CONCLUSIONS

The inclusion of imatinib in the radioimmunotherapy regimen is beneficial and it does not produce any overt side effects. The improved responses of pancreatic cancer xenografts to the multimodality treatment comprising radioimmunotherapy and platelet-derived growth factor receptor-beta inhibition suggest that this approach to therapy of pancreatic cancer may also be successful in patients.

Apoptosis, proliferation and differentiation patterns are influenced by Zebularine and SAHA in pancreatic cancer models

OBJECTIVE

Pancreatic cancer continues to be an urgent clinical problem. We used the novel DNA methyltransferase inhibitor Zebularine and the histone deacetylase inhibitor SAHA to investigate the epigenetic influence on viability and differentiation of the pancreatic cancer cell lines YAP C, DAN G and Panc-89 in vitro and in vivo.

MATERIAL AND METHODS

Cell vitality, proliferation and expression of PDX-1, cytokeratin 7 and 20, chromogranin A, vimentin, bax and bcl-2 were determined on the protein and mRNA level in vitro and in a subcutaneous xenograft model.

RESULTS

A time- and dose-dependent increase of apoptosis, paralleled by decreased proliferation, was observed after incubation with single agents or a combination therapy with lower concentrations. This was associated with up-regulation of pro-apoptotic bax and a phenotypic stabilization by the enhanced expression of cytokeratin 7. In vivo, growth of xenografts was delayed with the most pronounced effect in Panc-89 after 1 week of daily intraperitoneal injections of Zebularine paralleled with CK7 up-regulation and down-regulation of dedifferentiation markers.

CONCLUSIONS

Epigenetic modulation via inhibition of DNA methyltransferase and histone deacetylase induces apoptosis in human pancreatic cancer cells in vitro and delays xenograft growth in vivo, which is associated with a morphological/molecular phenotypic stabilization. These compounds may therefore be suitable as adjunctive therapeutic agents in the treatment of pancreatic cancer.

The stem cell factor/c-kit receptor pathway enhances proliferation and invasion of pancreatic cancer cells

BACKGROUND

The transmembrane protein c-kit is a receptor tyrosine kinase (KIT) and KIT is expressed in solid tumors and hematological malignancies such as gastrointestinal stromal tumor (GIST), small-cell lung cancer and chronic myelogenous leukemia (CML). KIT plays a critical role in cell proliferation and differentiation and represents a logical therapeutic target in GIST and CML. In pancreatic cancer, c-kit expression has been observed by immunohistochemical techniques. In this study, we examined the influence of c-kit expression on proliferation and invasion using five pancreatic cancer cell lines. In addition, the inhibitory effect of imatinib mesylate on stem cell factor (SCF)-induced proliferation and invasion was evaluated. Finally, we also analyzed KIT and SCF expression in pancreatic cancer tissues using immunohistochemistry and correlated the results with clinical features.

RESULTS

RT-PCR revealed that two pancreatic cancer cell lines, PANC-1 and SW1990, expressed c-kit mRNA. By Western blot analysis, c-kit protein was also present in those lines. In KIT-positive pancreatic cancer cell lines, proliferation and invasion were significantly enhanced by addition of SCF. In contrast, SCF did not enhance proliferation and invasion in the three KIT-negative lines (BxPC-3, Capan-2 and MIA PaCa-2). 5 muM imatinib mesylate significantly inhibited SCF-enhanced proliferation to the same extent compared with the control. Similarly, SCF-enhanced invasive ability was significantly inhibited by 5 muM imatinib mesylate. KIT was expressed in 16 of 42 clinical specimens by immunohistochemistry, and KIT expression was significantly related to venous system invasion. Furthermore, patients expressing both KIT and SCF had a somewhat lower survival.

CONCLUSION

Our results demonstrated that the SCF-KIT pathway enhanced the proliferation and invasiveness in KIT-positive pancreatic cancer cell lines and that the enhanced proliferation and invasion were inhibited by imatinib mesylate. We propose that inhibitors of c-kit tyrosine kinase receptor have the potential to slow the progression of KIT-positive pancreatic cancers.

An unusual case of undifferentiated carcinoma in situ with osteoclast-like giant cells of the pancreas

OBJECTIVES

We report an unusual case of undifferentiated carcinoma in situ with osteoclast-like giant cells (UC with OGCs) in a 68-year-old Japanese woman.

METHODS

Preoperative examinations revealed an unidentifiable mass lesion within the main pancreatic duct (MPD) in the pancreatic head, accompanied by a dilated MPD distal to the mass lesion, which was suspected to be an intraductal papillary-mucinous neoplasm of the main-duct type with acute pancreatitis because of an increased serum amylase level. A pancreaticoduodenectomy was performed.

RESULTS

A pencil-like tumor occupied the lumen of the MPD of the pancreatic head without a visible pancreatic parenchymal mass. The intraductal tumor included a sheet of spindle cells intermingled with scattered OGCs and pleomorphic giant cells. A poorly developed glandular pattern was occasionally observed at the tumor periphery. These findings were consistent with conventional UC with OGCs. However, extraductal invasion was not found in an extensive histopathologic examination, although focal intraductal spreading into the epithelium of the first branch of the MPD was observed.

CONCLUSIONS

Undifferentiated carcinoma with OGCs usually exhibits an invasive tumor at diagnosis and is associated with a poor outcome, but the patient is alive without recurrence 22 months after surgery. To our knowledge, this is the first reported case of UC in situ without evident extraductal invasion in English literature.

The tyrosine kinase inhibitor imatinib fails to inhibit pancreatic cancer progression

Imatinib targets KIT and platelet-derived growth factor receptors (PDGFR) and is highly effective in the treatment of CML and GIST patients. Pancreatic cancers express KIT and PDGFRs. Therefore, 26 patients with unresectable pancreatic cancer were randomized to either gemcitabine (1000 mg/m2 weekly) or imatinib (2x400 mg po) treatment daily. Pancreatic adenocarcinoma was confirmed histologically and expression of KIT and PDGFRbeta was determined immunohistochemically in the biopsy specimens. Quality of life was assessed with two standard questionnaires. No objective responses were seen in either group. Median time to progression was 77 and 29 days (P=0.411) and median survival time was 140 and 60 days (P=0.517) for gemcitabine and imatinib, respectively. Survival and treatment responses were independent of KIT and PDGFRbeta expression in patients treated with imatinib. Grade 3/4 toxicities of imatinib treatment were anemia, elevated liver enzymes, vomiting, and dyspnea. Patients treated with imatinib reported diarrhoea and/or altered bowel function more frequently, which were treatable symptomatically. Quality of life was similar in both groups. In this small series of pancreatic cancer patients, treatment with imatinib was not associated with a significant control of cancer progression.

A distinct expression pattern and point mutation of c-kit in papillary renal cell carcinomas

KIT is expressed not only in tumors derived from hematopoietic stem cells, melanocytes, germ cells, mast cells, and interstitial cells of Cajal, but also in other malignancies such as chromophobe renal cell carcinoma. This pattern of KIT expression prompted us to investigate the expression and mutation of c-kit gene exons 9, 11, 13, 17, and intron 17 in the different subtypes of renal cell carcinomas (n=66) and non-neoplastic kidneys (n=12). We found that KIT showed strong immunoreactivity in the cytoplasm of papillary renal cell carcinomas (100%), but on the cell membranes of chromophobe renal cell carcinomas (100%). Interestingly, a specific point mutation of the c-kit intron 17 (T->A) was found only in papillary renal cell carcinomas (94%). Our study demonstrates that the expression pattern and one mutation of c-kit may distinguish papillary renal cell carcinomas.