Cyclin D3 immunoreactivity in gastrointestinal stromal tumors is independent of cyclin D3 gene amplification and is associated with nuclear p27 accumulation

Cyclin D1 is a mediator of gastrointestinal stromal tumor KIT-independence

Oncogenic KIT or PDGFRA tyrosine kinase mutations are compelling therapeutic targets in most gastrointestinal stromal tumors (GISTs), and the KIT inhibitor, imatinib, is therefore standard of care for patients with metastatic GIST. However, some GISTs lose expression of KIT oncoproteins, and therefore become KIT-independent and are consequently resistant to KIT-inhibitor drugs. We identified distinctive biologic features in KIT-independent, imatinib-resistant GISTs as a step towards identifying drug targets in these poorly understood tumors. We developed isogenic GIST lines in which the parental forms were KIT oncoprotein-dependent, whereas sublines had loss of KIT oncoprotein expression, accompanied by markedly downregulated expression of the GIST biomarker, protein kinase C-theta (PRKCQ). Biologic mechanisms unique to KIT-independent GISTs were identified by transcriptome sequencing, qRT-PCR, immunoblotting, protein interaction studies, knockdown and expression assays, and dual-luciferase assays. Transcriptome sequencing showed that cyclin D1 expression was extremely low in two of three parental KIT-dependent GIST lines, whereas cyclin D1 expression was high in each of the KIT-independent GIST sublines. Cyclin D1 inhibition in KIT-independent GISTs had anti-proliferative and pro-apoptotic effects, associated with Rb activation and p27 upregulation. PRKCQ, but not KIT, was a negative regulator of cyclin D1 expression, whereas JUN and Hippo pathway effectors YAP and TAZ were positive regulators of cyclin D1 expression. PRKCQ, JUN, and the Hippo pathway coordinately regulate GIST cyclin D1 expression. These findings highlight the roles of PRKCQ, JUN, Hippo, and cyclin D1 as oncogenic mediators in GISTs that have converted, during TKI-therapy, to a KIT-independent state. Inhibitors of these pathways could be effective therapeutically for these now untreatable tumors.

Correlation between P53 expression and malignant risk of gastrointestinal stromal tumors: evidence from 9 studies

PURPOSE

The published data about p53 expression and its potential value in malignant risk of Gastrointestinal Stromal Tumors patients seemed inconclusive. To derive a more precise estimation of the relationship between p53 and Malignant risk of GIST, a meta-analysis was performed.

MATERIALS AND METHODS

Studies have been identified by searching PubMed and Embase. Inclusive criteria were GIST patients, evaluation of p53 expression and malignant risk. The odds ratio (OR) for positive rate of p53 in NIH very low risk group vs. NIH low risk group, the odds ratio (OR) for positive rate of p53 in NIH low risk group vs. NIH Intermediate risk group and the odds ratio (OR) for positive rate of p53 in NIH Intermediate group vs. NIH high risk group were calculated with 95% confidence interval (CI) for each study as an estimation of potential value of p53 in malignant risk of GIST.

RESULTS

A total of 9 studies including 768 patients were involved in this meta-analysis. The meta-analysis of positive rate of p53 in NIH VL group vs. NIH L group did not attain significant difference (OR 0.38 95% CI, 0.11-1.28; P = 0.12 P(heterogeneity) = 0.51). However the overall OR for positive rate of p53 in NIH L group vs. NIH I group revealed that significantly elevated risks of positive p53 in NIH I group were achieved (OR 0.44 95% CI, 0.24-0.82; P = 0.009 P(heterogeneity) = 0.32). The overall OR for NIH I group vs. NIH H group was 0.62 (95% CI, 0.37-1.02; P = 0.06 P(heterogeneity) = 0.25).

CONCLUSION

The results indicate p53 overexpression correlate with the malignant risk increasing of GIST and have a primary and closest relationship within the NIH I risk group of GIST.

Gastrointestinal stromal tumours: origin and molecular oncology

Gastrointestinal stromal tumours (GISTs) are a paradigm for the development of personalized treatment for cancer patients. The nearly simultaneous discovery of a biomarker that is reflective of their origin and the presence of gain-of-function kinase mutations in these tumours set the stage for more accurate diagnosis and the development of kinase inhibitor therapy. Subsequent studies of genotype and phenotype have led to a molecular classification of GIST and to treatment optimization on the basis of molecular subtype. The study of drug-resistant tumours has advanced our understanding of kinase biology, enabling the development of novel kinase inhibitors. Further improvements in GIST treatment may require targeting GIST stem cell populations and/or additional genomic events.

Gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) have emerged from being poorly defined, treatment-resistant tumors to a well-recognized, well-understood, and treatable tumor entity within only one decade. The understanding of GIST biology has made this tumor a paradigm for molecularly targeted therapy in solid tumors and provides informative insights into the advantages and limitations of so-called targeted therapeutics. Approximately 85% of GISTs harbor activating mutations in KIT or the homologous receptor tyrosine kinase PDGFRA gene. These mutations are an early event in GIST development and the oncoproteins serve as a target for the small molecule tyrosine kinase inhibitors imatinib and sunitinib. The existing and emerging treatment options demand exact morphologic classification and risk assessment. Although, KIT (CD117) immunohistochemistry is a reliable diagnostic tool in the diagnosis of GIST, KIT-negative GISTs, GISTs showing unusual morphology as well as GISTs which progress during or after treatment with imatinib/sunitinib can be a challenge for pathologists and clinicians. This review focuses on GIST pathogenesis, morphologic evaluation, promising new immunohistochemical markers, risk assessment, the role of molecular analysis, and the increasing problem of secondary imatinib resistance and its mechanisms.

Cyclin D1 and D3 overexpression predicts malignant behavior in thyroid fine-needle aspirates suspicious for Hurthle cell neoplasms

BACKGROUND

Thyroid fine-needle aspiration (FNA) samples that feature a follicular-patterned, monotonous Hurthle (oncocytic) cell population cannot be diagnosed reliably. The authors of this report recently identified cyclin D3 overexpression on histologic sections of Hurthle cell carcinoma. In this study, they assessed the diagnostic value of cyclin D3 immunohistochemistry added to routine cytology.

METHODS

Fifty-one FNA samples that were suspicious for Hurtle cell neoplasia and that had histologic follow-up (19 malignant cases) were examined. Cyclin D3 expression levels were evaluated in cell block preparations and were compared with levels of the closely related cyclin D1 protein.

RESULTS

Greater than 25% positive cells were used as the cutoff point, as suggested by previous studies. Cyclin D1 and cyclin D3 were highly specific (100% for both) and fairly accurate (75% and 92%, respectively) in distinguishing between benign and malignant oncocytic lesions; the positive predictive value (PPV) for each was 100%. However, both cyclins D1 and D3 had low sensitivity (32% and 79%, respectively) and low negative predictive value (NPV) (71% and 89%, respectively). In contrast, by adopting balanced receiver operating characteristic-derived positive cutoff values, cyclin D1 (>or=6.5%) and cyclin D3 (>or=7.5%) were found to be highly sensitive (100% for both) and accurate (90% and 94%, respectively); and the NPV was 100% for both. In contrast, cyclins D1 and D3 had low specificity (84% and 91%, respectively) and a low PPV (79% and 86%, respectively); however, these values improved in samples that were positive for both cyclins (sensitivity, 100%; specificity, 94%; PPV, 90%; NPV, 100%; and accuracy, 96%).

CONCLUSIONS

Cyclin D3 increased the suspicion of malignancy in indeterminate oncocytic lesions; its diagnostic performance depended on the cutoff point used and was enhanced further when combined with cyclin D1.

Contemporary pathology of gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. The vast majority of GISTs harbor a KIT or PDGFRA mutation and express KIT by immunohistochemistry. However, KIT-negative tumors and tumors showing unusual morphologic features can cause major diagnostic problems. The ability to inhibit the active KIT or PDGFRA kinase with tyrosine kinase inhibitors and alternative drugs demands more than ever accurate tumor classification and risk assessment. This article focuses on the pathology of GIST, including unusual variants and morphologic changes resulting from treatment. Parameters for risk assessment, potentially helpful new immunohistochemical markers, differential diagnosis, and the application of molecular classification schemes are discussed.

Molecular pathobiology of gastrointestinal stromal sarcomas

Gastrointestinal stromal tumors (GISTs) form an interesting group of sarcomas whose unique pathobiology provides a model of how molecularly targeted therapeutics can have a major impact on patient welfare. Approximately 85% of GISTs are driven by oncogenic mutations in either of two receptor tyrosine kinases: KIT or platelet-derived growth factor receptor alpha. We review the pivotal relationship between specific mutations in these kinase genes, the origin and pathologic spectrum of GISTs, and the response of these tumors to treatment with kinase inhibitors such as imatinib and sunitinib. Mechanisms of resistance to kinase inhibitor therapy are discussed, and targets for the next generation of therapeutics are considered. The rapid evolution in our understanding of GISTs, which stems directly from the close alliance of basic and clinical researchers in the field, illustrates the growing role of the molecular classification of solid tumors in the development of modern oncological treatments.

Skp2 expression is associated with high risk and elevated Ki67 expression in gastrointestinal stromal tumours

Background

Gastrointestinal stromal tumors (GIST) exhibit an unpredictable clinical course and can rapidly progress to lethality. Predictions about the biological behavior of GIST are based on a number of canonical clinical and pathologic parameters whose validity in distinguishing between a benign and a malignant tumour is still imperfect. The aim of our study was to investigate the role of morphologic parameters and expression of cells cycle regulators as prognosticators in GIST.

Methods

We performed an immunohistochemical analysis for Ki67, p27^Kip1, Jab1, and Skp2, on a Tissue Microarray (TMA) containing 94 GIST. Expression of the above proteins was correlated to classically used prognosticators, as well as to risk groups. Clinical significance of histologic and immunohistochemical features were evaluated in 59 patients for whom follow-up information was available.

Results

Overexpression of Ki67 and Skp2, and p27^Kip1 loss directly correlated with the high risk group (p = 0.03 for Ki67 and Skp2, p = 0.05 for p27^Kip1). Jab1 expression did not exhibit correlation with risk. In 59 cases provided with clinical follow-up, high cellularity, presence of necrosis, and Ki67 overexpression were predictive of a reduced overall survival in a univariate model. The same parameters, as well as mitotic rate, tumour size, and p27^Kip1 loss were indicative of a shortened relapse free survival interval. High cellularity, and high mitotic rate retained their prognostic significance by multivariate analysis.

Conclusion

Our data suggest that a number of histologic parameters in combination with immunohistochemical expression of cell cycle regulators can facilitate risk categorization and predict biologic behavior in GIST. Importantly this study demonstrates, for the first time, that Skp2 expression correlates with Ki67 expression and high risk in GIST.

Gastrointestinal stromal tumours overexpress fatty acid synthase

Fatty acid synthase (FASN), a key enzyme for de novo lipogenesis, is overexpressed in many malignant tumours and is associated with aggressive biological behaviour. FASN expression and its possible relationship with more aggressive behaviour in gastrointestinal stromal tumours (GISTs) have not been addressed to date. Here, FASN expression was assessed by immunohistochemistry in 60 primary GISTs (28 low/intermediate risk and 32 high risk) and seven metastatic GISTs. Sixteen smooth muscle gastrointestinal tumours were used as controls. FASN was overexpressed in 36 of 60 GISTs (60%): in 12 of 28 (42%) low/intermediate-risk GISTs and in 24 of 32 (75%) high-risk GISTs (p<0.05). Two primary and seven metastatic GISTs and five GIST cell lines (GIST882, GIST430, GIST522, GIST62, and GIST48), analysed by western blot, showed variable FASN expression. Most metastatic samples expressed high levels of FASN protein. Additionally, seven of 60 GISTs showed a proliferation rate higher than 10% by Ki67 and all of them expressed FASN (p<0.04). Finally, proliferation and apoptosis were investigated after FASN silencing in GIST882 cells, which displayed the highest FASN expression. siRNA-mediated FASN knock-down inhibited expression of the proliferation marker cyclin A, whereas no changes in p27 and cleaved PARP expression were seen. It is concluded that FASN is preferentially overexpressed in high-risk and metastatic GISTs, and that its overexpression likely contributes to cell proliferation.

Accumulation of p27(kip1) is associated with cyclin D3 overexpression in the oxyphilic (Hurthle cell) variant of follicular thyroid carcinoma

BACKGROUND

The down regulation of protein p27(kip1) (p27) in most cases of thyroid cancer has relevant diagnostic and prognostic implications. However, the oxyphilic (Hurthle cell) variant of follicular thyroid carcinoma expresses more p27 than benign oxyphilic lesions do.

AIM

To evaluate the mechanism underlying this difference in expression of p27.

METHODS

Because high levels of cyclin D3 lead to p27 accumulation in cell lines and clinical samples of thyroid cancer, the immunocytochemical pattern of cyclin D3 in oxyphilic (n = 47) and non-oxyphilic (n = 70) thyroid neoplasms was investigated.

RESULTS

In the whole study sample, there was a significant correlation between p27 and cyclin D3 expression (Spearman's r: 0.64; p<0.001). The expression of cyclin D3 and p27 was significantly higher in the oxyphilic variant of follicular carcinomas than in non-oxyphilic carcinomas (p<0.001). In the former, cyclin D3 overexpression and p27 accumulation were observed in a median of 75% and 55% of cells, respectively. In co-immunoprecipitation experiments, the level of p27-bound cyclin D3 was much higher in oxyphilic neoplasias than in normal thyroids and other thyroid tumours.

CONCLUSION

These results show that increased p27 expression in the oxyphilic (Hurthle cell) variant of follicular thyroid carcinoma results from cyclin D3 overexpression.

Altered expression of cell cycle regulatory proteins in gastrointestinal stromal tumors: markers with potential prognostic implications

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the digestive tract. The prediction of the malignant potential of GISTs is still difficult. Altered cell cycle regulation may underlie the tumorigenesis and/or the progression of human malignancies. Although p53 and Bcl-2 have been extensively investigated in GISTs, little is known about the frequency of expression and possible clinical implications of alterations of other cell cycle regulatory proteins in these neoplasms. We have previously investigated the role of loss of p16(INK4A) by loss of heterozygosity and immunohistochemistry in the progression of GISTs and found that loss of heterozygosity of 9p and loss of p16 expression are confined to malignant GISTs. This has led us to investigate the role of other cell cycle regulatory proteins in these tumors. Twenty-three cases of GIST (9 low malignant potential [LMP], 10 primary malignant, and 4 intra-abdominal recurrences) were examined. All cases were strongly positive for KIT (CD117). Immunohistochemical stains were carried out on tissue microarrays to evaluate the expression of proteins involved in the G(1)-S transition and proteins that regulate apoptosis including Rb, E2F1, cyclin D1, CDK4, CDK6, p27(KIP1), p21(WAF1/CIP1), p53, Mdm2, Bcl-2, and Bax. The positive phenotypes identified were as follows: Rb, 39.1%; E2F1, 69.6%; cyclin D1, 30.4%; CDK4, 100%; CDK6, 30.4%; 39.1%; p27(KIP1), 47.8%; p21(WAF1/CIP1), 39.1%; p53, 43.5%; Mdm2, 17.4%; Bcl-2, 91.3%; and Bax, 100%. Malignant GISTs are more likely to be associated with a positive E2F1 and p53 phenotype and a negative p16 and p27(KIP1) phenotype. It was concluded that aberration of the cell cycle regulators is a frequent finding and may be a contributing factor to the pathogenesis of GISTs. While some alterations are seen in LMP and malignant GISTs and therefore may represent an early event in molecular tumorigenesis of GISTs, other alterations are more common in malignant GISTs than LMP and therefore have potential utility as complementary tools for the prognostication of GISTs.

Prognostic significance of expressions of cell-cycle regulatory proteins in gastrointestinal stromal tumor and the relevance of the risk grade

Gastrointestinal stromal tumors (GISTs) have a wide spectrum of biologic behavior ranging from benign to malignant. Risk grading based on tumor size and mitotic counts has been proposed in an effort to predict the adverse outcome of GIST in the literature so far. Recent molecular studies have reported the prognostic values of several parameters, including alteration of cell-cycle regulators. The aim of this study was to elucidate the prognostic values of risk grade and alterations of cell-cycle-related proteins, including Ki-67, cyclin A, cyclin B1, cyclin D1, cyclin E, p16, p21, p27, p53, cdc2, and cdk2, in addition to the conventional factors. Eighty cases of primary c-kit-positive GISTs were classified into 2 cases of very-low-risk grade, 20 cases of low-risk grade, 25 cases of intermediate-risk grade, and 33 cases of high-risk grade. The risk grade was correlated with the presence of metastases and/or recurrence. A high level of Ki-67 and cyclin A expression was correlated with risk grade (P = .0027 and .0441, respectively). Overexpression of G2-M regulators, such as cyclin A, cyclin B1, and cdc2, was associated with the Ki-67 labeling index (LI) (P = .0007, .0475, and .0040, respectively). According to univariate analysis, tumor grade (high risk), tumor size (> or =5 cm), mitotic counts (> or =5/50 high-power fields), Ki-67 LI (> or =4.92%), cyclin A LI (> or =1.61%), and cdc2 LI (> or =1.25%) were all found to be significantly associated with a shorter period of disease-free survival (P = .0001, .0270, .0004, .0001, .0001, and .0011, respectively). According to multivariate analysis, both high Ki-67 LI and high-risk grade were found to be significantly associated with a shorter period of disease-free survival (P = .0083 and .0246, respectively). In conclusion, our results strongly support the hypothesis that Ki-67 LI and risk grade are useful for predicting the aggressive biologic behavior of GISTs. Furthermore, alteration of G2-M regulators, such as cyclin A, cyclin B1, and cdc2, is also a useful marker for predicting aggressive behavior and play an important role, at least in part, in the cell proliferation of GIST.

Patterns of gene amplification in gastrointestinal stromal tumors (GIST)

Gastrointestinal stromal tumors (GIST) are the most common primary mesenchymal tumors of the gastrointestinal tract (GIT). They represent a wide clinico-pathological spectrum of tumors. No single histological or clinical parameter can predict the prognosis while the response to therapy is related to the type of KIT or PDGFRA mutation. Cytogenetic and CGH studies have identified frequent gross chromosomal aberrations but the target genes of these changes are unknown. To determine whether known oncogenes take part in genomic rearrangements and to investigate the potential clinical significance of their amplifications, nine known oncogenes (CMYC, MDM2, GLI1, CDK4, HER2, EGFR1, CCND1, FGF3, EMS) were analyzed by fluorescent in situ hybridization (FISH) on a tissue microarray (TMA) containing 94 primary GIST. Clinical follow-up information was available for 57 of these patients. Amplification was found for CMYC in three of 90 (3.3%), for MDM2 in five of 94 (5.3%), for EGFR1 in five of 94 (5.3%), and for CCND1 in seven of 79 (8.9%) evaluable cases. No amplifications were seen for HER2, GLI1, CDK4, FGF3, and EMS. Amplifications of MDM2 and CCND1 were associated with clinical and histological malignancy. In conclusion, our data show that gene amplification does occur in a subset of GIST. Identification of MDM2/CCND1 amplification may represent another molecular feature that could help in the evaluation of the behavior of GISTs.

Cyclin D3 expression in normal fetal, normal adult and neoplastic feline tissue

Cyclin D3 is a tightly regulated cell cycle protein and member of the cyclin D family-a group of proteins that facilitates the progression of a cell through G(1) and into the S phase of the cell cycle. All cells use at least one of the cyclin D proteins for cell cycle regulation. In this study, feline tissues (normal fetal and adult, and neoplastic) were examined immunohistochemically for expression and topographical distribution of cyclin D3. Its distribution was similar to that in human tissues in health and neoplasia, and suggested a dual role of cyclin D3 in cell proliferation and differentiation. Immature lymphoid tissue and proliferating epithelial cells in health and neoplasia were immunoreactive for cyclin D3, whereas expression of the protein in other immunoreactive tissues reflected differentiated cell types. Immunoreactivity for cyclin D3 was particularly striking in germinal centre cells of normal lymph nodes and B-cell lymphomas, and in normal suprabasal epithelial cells of the skin and mucous membranes of the oropharynx and in squamous cell carcinomas at these sites.

Cyclin D3 Immunoreactivity Is an Independent Predictor of Survival in Laryngeal Squamous Cell Carcinoma

Purpose: To analyze the prevalence and clinical relevance of cyclin D3 abnormalities in laryngeal squamous cell carcinoma (LSCC).

Experimental Design: Cyclin D3 immunoreactivity was evaluated in 223 formalin-fixed and paraffin-embedded samples of LSCC patients with a mean follow-up of 62.8 ± 43.2 months. The occurrence of cyclin D3 extra signals was analyzed by fluorescence in situ hybridization in 47 randomly selected cases collected in a tissue microarray. Cyclin D1 immunoreactivity had been previously investigated in 133 cases.

Results: Cyclin D3 immunoreactivity and gene extra signals were found in 39.5% and 42.6% of the cases, respectively, and the concordance between immunohistochemical and fluorescence in situ hybridization results was 70.2% (P = 0.0085). Cyclin D3 immunoreactivity was significantly associated with a high risk of death. Multivariate analysis showed that high tumor grade, exophytic/ulcerating tumor type, low performance status, and cyclin D3 immunoreactivity were the only independent predictors of poor overall survival. In the 133 cases analyzed for both cyclin D1 and cyclin D3, patients with cyclin D1+/cyclin D3+ tumors experienced the worst prognosis, patients with cyclin D1−/cyclin D3− exhibited the most prolonged survival, and with cyclin D1−/cyclin D3+ or cyclin D1+/cyclin D3− tumors an intermediate course was associated.

Conclusions: Our data suggest that cyclin D3 immunoreactivity, possibly due to the occurrence of gene extra copies, may represent an adjunct in LSCC patients' prognostication and contribute to identify D-type cyclins as potential targets of newly developed therapies.