Immunohistochemical expression of p16INK4A, Ki-67, and Mcm2 proteins in gastrointestinal stromal tumors: prognostic implications and correlations with risk stratification of NIH consensus criteria

Establishment of the prediction model and biological mechanism exploration for secondary imatinib-resistant in gastrointestinal stromal tumor

A gastrointestinal stromal tumor (GIST) is mostly driven by the auto-activated, mutant KIT receptor tyrosine kinase gene or by the platelet-derived growth factor receptor alpha. Inhibition of KIT-signaling is the primary molecular target therapy for GIST, which is performed by the drug imatinib clinically. However, more than half of advanced or metastatic GIST develop secondary resistance to imatinib within 2 years after initiation of treatment, and the mechanism of acquired imatinib-resistant in GIST remains unclear. Therefore, we designed the present study, and firstly analyzed the gene expression profile of imatinib-resistant and sensitive GIST from GEO DataSet and identified 44 differential expressed genes. Then, a model including nine genes with their expressed coefficients was identified as a risk score to predict imatinib-resistant GIST. Internal and external validation of the prediction model was performed through the ROC curve, and the area under the curve was 0.967 (95%CI 0.901-1.000) and 0.917 (95%CI 0.753-1.000), separately. Lastly, the effect of immune, m⁶A, pyroptosis, and ferroptosis-related genes on imatinib-resistant GIST was also assessed because DNA replication was the most enriched biological function of DEGs after functional annotation, pathway enrichment, and protein-protein interaction network analyses. In conclusion, the present study established a novel model to predict secondary imatinib-resistant GIST. Meanwhile, the bioinformatic mining results provided potential and promising targets for imatinib-resistant therapy.

High MCM6 Expression as a Potential Prognostic Marker in Clear-cell Renal Cell Carcinoma

AIM

Minichromosome maintenance (MCM) proteins are involved in initiation of DNA replication and cell-cycle progression. Loss of MCM function results in genomic instability and causes carcinogenesis. Among MCM genes, the role and prognostic value of MCM6 expression in clear-cell renal cell carcinoma (ccRCC) has not been elucidated.

MATERIALS AND METHODS

We assessed the mRNA expression level of MCM6 using the Gene Expression Profiling Interactive Analysis database and investigated MCM6 protein expression by immunohistochemistry in 238 ccRCC cases.

RESULTS

High MCM6 expression was significantly associated with increasing tumor size, pT, stage, tumor necrosis, and metastasis. Furthermore, high MCM6 expression was significantly associated with shorter overall and disease-free survival, and was an independent unfavorable prognostic marker. Regarding patients with metastasis, high MCM6-expressing ccRCC conferred significantly shorter survival than for those with low expression.

CONCLUSION

A high MCM6 expression level may be a promising biomarker to predict tumor progression, metastasis, and survival in patients with ccRCC.

Loss of SFRP1 expression is a key progression event in gastrointestinal stromal tumor pathogenesis

The mechanism of high-grade transformation in gastrointestinal stromal tumors (GISTs) remains to be clarified. We aim to discover the key progression events by studying biphasic GISTs. The study group included 101 GISTs. Nineteen of these had been screened from 263 GISTs to represent the early stage of GIST high-grade transformation, characterized by juxtaposed low-grade and high-grade regions in the same tumor (so-called biphasic GISTs). Mutational analyses, fluorescence in situ hybridization (FISH), NanoString analyses, telomere analysis, and gene expression profiling were carried out, followed by in silico analyses, cell line study, and immunohistochemical validation. Using gene expression analysis, downregulation of SFRP1 was revealed to be the main event in GIST high-grade transformation (p = 0.013), accompanied by upregulation of EZH2. In silico analyses revealed that downregulation of SFRP1 was a common feature in GIST progression across several different series. Immunohistochemically, the expression of SFRP1 was validated to be significantly lower in high-grade GISTs (WHO risk group 3a or higher) than in low-grade GISTs (p < 0.001), and attenuation/loss of SFRP1 was associated with GIST tumor progression (p < 0.001). By NanoString and FISH analyses, chromosomal 9/9p loss was the only recurrent large-scale chromosome aberration in biphasic GISTs, with a correlation with SFRP1 downregulation. Subclones containing chromosome 9/9p loss could be appreciated in the low-grade parts of biphasic GISTs. TP53 mutation, RB1 loss, KIT/PDGFRA mutation, and alternative lengthening of telomeres did not play a significant role in GIST high-grade transformation. In conclusion, high-grade transformation of GISTs features SFRP1 downregulation and chromosome 9/9p loss.

KIF15 Expression in Tumor-associated Monocytes Is a Prognostic Biomarker in Hepatocellular Carcinoma

BACKGROUND/AIM

Kinesin family member 15 (KIF15) participates in the transport of macromolecules in essential cellular processes. In this study we evaluated the clinical relevance of KIF15 expression in hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Association between KIF15 expression and clinical outcomes in HCC patients was analyzed using three independent cohorts. Localization of KIF15 expression was assessed by immunohistochemical analysis. Co-culture experiments were performed using healthy donor peripheral blood mononuclear cells (PBMC) and HCC cell lines.

RESULTS

Immunohistochemical analysis showed that KIF15 was mainly expressed in inflammatory monocytes around cancer cells. Multivariate analysis indicated high KIF15 expression was an independent poor prognostic factor for survival. HCC cells with high expression of minichromosome maintenance protein 2 (MCM2) were located close to KIF15-expressing inflammatory monocytes. The proliferation ability of HCC cells was increased by co-culture with PBMC.

CONCLUSION

High KIF15 expression in inflammatory monocytes in tumor tissues may serve as a prognostic marker for poor outcome in HCC.

Enhanced anticancer activity of combined treatment of imatinib and dipyridamole in solid Ehrlich carcinoma-bearing mice

The current study was designed to evaluate potential enhancement of the anticancer activity of imatinib mesylate (IM) with dipyridamole (DIP) and to investigate the underlying mechanisms of the combined therapy (IM/DIP) to reduce hepatotoxicity of IM in solid Ehrlich carcinoma (SEC)-bearing mice. SEC was induced in female albino mice as a model for experimentally induced breast cancer. Mice were randomly divided into seven groups (n = 10): SEC vehicle, IM₅₀ (50 mg/kg), IM₁₀₀ (100 mg/kg), DIP (35 mg/kg), a combination of IM₅₀/DIP and IM₁₀₀/DIP. On day 28th, mice were sacrificed and blood samples were collected for hematological studies. Biochemical determination of liver markers was evaluated. Glutamic oxaloacetic transaminase (SGOT), glutamic pyruvic transaminase (SGPT) and alkaline phosphatase (ALP) levels were assessed. In addition, MDR-1 gene expression and immunohistochemical staining of BAX and BCL-2 was done. Also, in vitro experiment for determination of IC50 of different treatments and combination index (CI) were assessed in both MCF-7 and HCT-116 cell lines. IM- and/or DIP-treated groups showed a significant reduction in tumor volume, weight, and serum levels of SGOT, SGPT, and AIP compared to vehicle group. In addition, reduction of VEGF, Ki67, and adenosine contents was also reported by treated groups. Also, IM/DIP combination showed lower IC50 than monotherapy. Combination index is less than 1 for IM/DIP combination in both cell lines. DIP as an adjuvant therapy potentiated the cytotoxic effect of IM, ameliorated its hepatic toxicity, and showed synergistic effect with IM in vitro cell lines. Furthermore, the resistance against IM therapy may be overcome by the use of DIP independent on mdr-1 gene expression.

Clinicopathologic Characteristics and Optimal Surgical Treatment of Duodenal Gastrointestinal Stromal Tumor

BACKGROUND

The clinicopathologic characteristics of duodenal gastrointestinal stromal tumor (GIST) were unclear and the optimal surgical procedure for duodenal GIST remains poorly defined. We aimed to analyze clinicopathological characteristics, survival outcomes based on the surgical procedure, and recommend optimal surgical treatment for duodenal GIST.

METHODS

From July 2000 to April 2017, 118 patients with localized duodenal GIST underwent curative surgical resection at a single institution. We retrospectively reviewed the clinicopathological characteristics and survival outcomes.

RESULTS

The 5-year overall survival (OS) and disease-free survival (DFS) rates were 94.9 and 79.2%, respectively. On multivariate analysis, the mitotic count was a statistically significant prognostic factor for DFS. Limited resection (LR) was performed in 20 patients with GIST in the first or fourth portion of the duodenum. Both LR and pancreaticoduodenectomy (PD) were performed in 98 patients with GIST in second or third portion of the duodenum. The patients in the LR group had less late complications than in the PD group and no postoperative newly developed diabetes mellitus. The minimally invasive LR (MI-LR) group had a shorter duration of surgery and shorter length of postoperative hospital stay.

CONCLUSION

LR is a feasible and effective surgical treatment for patients with small-sized and antimesenteric-sided duodenal GIST in terms of late complications and postoperative diabetic complications. MI-LR has better perioperative outcomes than open LR. Therefore, we should consider MI-LR as an optimal surgical treatment for selected patients with duodenal GIST.

Clinicopathologic analysis of gastrointestinal stromal tumors in duodenum and small intestine

BACKGROUND

The prognosis about duodenal GISTs is debatable. The purpose of this study is to compare the characteristics and the prognostic factors in patients with gastrointestinal stromal tumor (GIST) located in the duodenum with those located in the small intestine.

METHODS

One hundred-one patients with GIST located in the duodenum (n = 40), or small intestine (n = 61) underwent resection between 1996 and 2010. We analyzed clinicopathologic features, surgical outcomes, and prognostic factors.

RESULTS

Five-year survival rate in patients with GIST located in the duodenum and small intestine were 66.6 and 80.8%, respectively (p = 0.018). After survival analysis, high mitotic count and tumor rupture were identified as independent adverse prognostic factors. Advanced T stage and absence of adjuvant imatinib treatment were adverse prognostic factors with marginal statistical significance. The rate of progressive disease was significantly higher in patients with duodenal GISTs (36.8%) than in those with small intestinal GIST (29.6%) (p = 0.024).

CONCLUSIONS

The clinicopathologic findings of duodenal GIST differ from those of small intestinal GIST. Patients with duodenal GIST have a worse prognosis than those with small intestinal GIST. Aggressive treatment including surgical resection should be considered for duodenal GIST, even if the risk is relatively low.

Does Immunohistochemistry for Discovered on GIST1 and Minichromosome Maintenance Protein7 Provide Additional Clinicopathological Value in Gastrointestinal Stromal Tumors?

BACKGROUND

The aim of the study was to investigate the expression of discovered on GIST 1 (DOG1) and minichromosome maintenance protein 7 (MCM7) in addition to the traditional markers, C-KIT and Ki-67, in gastrointestinal stromal tumors (GISTs) to specify the diagnosis and to evaluate their clinicopathological significance in GIST patients.

METHODS

Hematoxylin and eosin sections of 43 GISTs were re-examined to review histopathological criteria and risk stratification of these tumors. Immunohistochemistry for DOG1, C-KIT, MCM7, Ki-67 antibodies was performed.

RESULTS

Positive DOG1 and C-KIT expressions were found in 42 (97.7%) and 39 (90.7%) of cases, respectively. DOG1 and C-KIT expression scores were significantly correlated (P < 0.001). Among four C-KIT-negative GISTs, three cases were DOG1-positive. DOG1 was more sensitive and specific than C-KIT in the diagnosis of GISTs. High DOG1 expression scores were significantly associated with tumor size (P = 0.023) and risk (P = 0.037). Significant positive correlation was noted between MCM7 and Ki-67 labeling indices (LIs) (P < 0.001, r = 0.885). MCM7 demonstrated higher proliferation LIs than Ki-67. Significant associations were found between MCM7 and Ki-67 LIs and tumor size (P = 0.001 and 0.003 respectively), mitotic rate (P < 0.001 both) and risk stratification (P < 0.001 both) with a stepwise increase in MCM7 LIs with increasing tumor risk.

CONCLUSION

DOG1 is an important diagnostic tool for GISTs particularly in C-KIT-negative tumors. It may have a role in GISTs tumorogenesis and progression. Despite the established clinicopathological value of Ki-67 in GISTs, detection of MCM7 expression is recommended as a prognostic adjunct, given its better sensitivity for cellular proliferation and stepwise association with tumor risk.

Clinical significance of expression of KCTD-12 in gastrointestinal stromal tumors of the stomach

AIM: To investigate the expression of potassium channel tetramerization domain-containing 12 (KCTD-12) protein in gastrointestinal stromal tumors (GISTs) of the stomach and its clinical significance.

METHODS: The expression of KCTD-12 was immunohistochemically examined in 39 gastric GIST tissues, and its correlations with the clinicopathological parameters, National Institutes of Health (NIH) risk classification and Ki-67 labeling index were analyzed. Univariate and Cox multivariate analyses were used to evaluate the factors associated with 3-year recurrence-free survival (RFS) rate of patients with gastric GISTs.

RESULTS: Positive KCTD-12 expression was detected in 29 (74.4%) of the 39 gastric GIST tissues. The absence of KCTD-12 expression was associated with large tumor size, high mitotic count and NIH high-risk classification (P < 0.05). GISTs recurred after surgery in 10 of the 39 cases during the follow-up, and the 3-year RFS rate was 74.4%. Univariate analysis showed that tumor size, NIH risk classification, KCTD-12 expression and Ki-67 labeling index had an impact on the 3-year RFS rate of patients with GISTs of the stomach. On multivariate analysis, KCTD-12 [relative risk (RR) = 0.014; 95%CI: 0.001-0.320, P = 0.007] was shown to be a highly correlated predictor. The 3-year RFS rate of patients without KCTD-12 expression was only 30% compared with 89.7% in those with KCTD-12 expression (P = 0.001). The 3-year RFS rate of patients with KCTD-12 expression and a Ki-67 labeling index of 5% or less was 95.7%. The 3-year RFS rate of patients without KCTD-12 expression and a Ki-67 labeling index more than 5% was only 20%.

CONCLUSION: KCTD-12 is a useful and reliable biomarker for the prognosis of GISTs of the stomach, especially when combined with Ki-67 labeling index.

Risk factors for gastrointestinal stromal tumor recurrence in patients treated with adjuvant imatinib

BACKGROUND

Little is known about the factors that predict for gastrointestinal stromal tumor (GIST) recurrence in patients treated with adjuvant imatinib.

METHODS

Risk factors for GIST recurrence were identified, and 2 risk stratification scores were developed using the database of the Scandinavian Sarcoma Group (SSG) XVIII trial, where 358 patients with high-risk GIST with no overt metastases were randomly assigned to adjuvant imatinib 400 mg/day either for 12 or 36 months after surgery. The findings were validated in the imatinib arm of the American College of Surgeons Oncology Group Z9001 trial, where 359 patients with GIST were randomized to receive imatinib and 354 were to receive placebo for 12 months.

RESULTS

Five factors (high tumor mitotic count, nongastric location, large size, rupture, and adjuvant imatinib for 12 months) were independently associated with unfavorable recurrence-free survival (RFS) in a multivariable analysis in the SSGXVIII cohort. A risk score based on these 5 factors had a concordance index with GIST recurrence of 78.9%. When a simpler score consisting of the 2 strongest predictive factors (mitotic count and tumor site) was devised, the groups with the lowest, intermediate high, and the highest risk had 5-year RFS of 76.7%, 47.5%, and 8.4%, respectively. Both scores were strongly associated with RFS in the validation cohort (P < .001 for each comparison).

CONCLUSIONS

The scores generated were effective in stratifying the risk of GIST recurrence in patient populations treated with adjuvant imatinib. Patients with nongastric GIST with a high mitotic count are at a particularly high risk for recurrence.

Proteomic approach toward personalized sarcoma treatment: lessons from prognostic biomarker discovery in gastrointestinal stromal tumor

Sarcomas range from curable tumors to those causing death via metastasis and recurrence. Thus, there is an urgent need for biomarker identification in order to assess the degree of malignancy, predict prognosis, and evaluate possible therapies. Various proteomic approaches and different clinical materials have been used to this end, and candidate biomarkers have been reported for the different types of sarcomas. However, the sample size used in these biomarker studies was generally insufficient, and thus far, no biomarker has been proved useful in clinics. Given that sarcomas are rare, biomarker validation in this setting is more challenging than in other malignancies. In gastrointestinal stromal tumor, adjuvant therapy has proven to be effective. However, only 40% patients experience metastasis after curative surgery alone, and the rest of the patients may not need adjuvant therapy. Using a proteomic approach, we identified pfetin (potassium channel tetramerization domain containing 12, KCTD 12) as a novel prognostic biomarker for sarcoma, and immunohistochemically confirmed its clinical usefulness by a multiinstitutional validation study. Here, we describe our experience and discuss the critical points in the discovery of this biomarker.

HuR cytoplasmic expression is associated with increased cyclin A expression and inferior disease-free survival in patients with gastrointestinal stromal tumours (GISTs)

AIMS

HuR is an RNA-binding protein that post-transcriptionally modulates the expression of various target genes involved in carcinogenesis, such as CCNA2, which encodes cyclin A. The aim of this study was to evaluate the significance of HuR expression and subcellular localization in a large cohort of gastrointestinal stromal tumours (GISTs).

METHODS AND RESULTS

HuR immunostaining was assessable for nuclear and cytoplasmic expression in 341 cases on tissue microarrays of primary GISTs, of which 318, 296 and 193 cases were also characterized for Ki67 labelling, cyclin A immunoexpression, and KIT and PDGFRA receptor tyrosine kinase (RTK) genotypes, respectively. The results of HuR nuclear and cytoplasmic expression were correlated with disease-free survival (DFS) and clinicopathological, immunohistochemical and RTK genotypic variables. HuR cytoplasmic expression was present in 42% of primary GISTs, and was significantly related to epithelioid histology, larger tumour size, NIH risk category, and nuclear expression of Ki67 and cyclin A. Importantly, HuR cytoplasmic expression (P < 0.001) and cyclin A overexpression (P < 0.001) were strongly associated with worse DFS. Both variables remained independently predictive of adverse outcome [P = 0.020 and risk ratio (RR) 2.605 for cytoplasmic HuR; P = 0.026 and RR 2.763 for cyclin A].

CONCLUSIONS

HuR cytoplasmic expression not only correlates with adverse prognosticators and cyclin A overexpression, but also independently predicts worse DFS, indicating a causative role in conferring tumour aggressiveness.

Contribution of DOG1 expression to the diagnosis of gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GIST) are the most common mesenchymal tumors of the gastrointestinal tract, and the majority contain KIT or PDGFRA-activating mutations. However, up to 10% of GISTs are c-kit-negative. Antibodies with increased sensitivity and specificity for the detection of c-kit-negative GIST cases may be of value, especially because some of these cases may also benefit from tyrosine kinase inhibitor therapy. Hematoxylin and Eosin sections of 33 GISTs were re-examined in order to define histopathological criteria used in risk assessment of these tumors. Immunohistochemistry with a panel of antibodies [c-kit, DOG1 (discovered on GIST 1), CD34, smooth muscle actin (SMA), Desmin, S100 and Ki67] was performed on 5μm-thick paraffin sections of all tumors. Statistical analysis of immunohistochemical studies showed that DOG1 and CD117 were the most sensitive and specific antibodies in the diagnosis of GISTs. Other antibodies were unhelpful in confirming a diagnosis of GIST, but were particularly useful in the differential diagnosis. Reactivity for DOG1 may aid in the diagnosis of GISTs, which fail to express c-kit antigen, and lead to appropriate treatment with imatinib mesylate, an inhibitor of the KIT tyrosine kinase.

Duodenal gastrointestinal stromal tumors: review on clinical and surgical aspects

INTRODUCTION

Gastrointestinal stromal tumors (GISTs) arising in the duodenum represent a rare entity and can be very demanding to manage. The diagnosis can be difficult (as these tumors can be misdiagnosed as pancreatic head tumors), and to treat owing to the complex anatomy of the duodenum and of the pancreatic head. Complete resection may require extensive procedures such as pancreaticodudodenectomy.

METHODS AND RESULTS

An extensive literature review regarding clinico-pathological features, diagnostic investigations and surgical options in the management of duodenal GISTs has been performed.

CONCLUSIONS

Duodenal GISTs have uncertain malignant potential, and they may be asymptomatic, or present with abdominal pain or bleeding. A preoperative diagnosis can be difficult to obtain. Endoscopic ultrasound and fine needle aspiration cytology (FNAC) may be helpful. Surgical R0 resection remains the only curative approach. However, owing to the complex anatomy of the duodenum, limited resection is not always feasible. In these cases, extensive procedures such as pancreaticoduodenectomy or pancreas-preserving duodenectomy are the treatment of choice.

Evaluation of malignancy using Ki-67, p53, EGFR and COX-2 expressions in gastrointestinal stromal tumors

AIM

To investigate the role of expressions of Ki-67, p53, epidermal growth factor receptor (EGFR) and cyclooxygenase-2 (COX-2) in gastrointestinal stromal tumor (GIST) grading and prognosis.

METHODS

Tumor tissue was collected retrospectively from 96 patients with GIST. Antibodies against Ki-67, p53, EGFR and COX-2 were used for immunohistochemical staining. Tumor grading was designated according to a consensus system and the staining was quantified in 3 categories for each antibody in the statistical analysis.

RESULTS

The Ki-67 expression in GISTs was significantly associated with the size of the tumors, mitotic rate and the risk of malignancy (χ(2) = 15.51, P = 0.02; χ(2) = 22.27, P < 0.001; χ(2) = 20.05; P < 0.001). The p53 expression was also significantly correlated with mitotic rate and the risk of malignancy (χ(2) = 9.92, P = 0.04; χ(2) = 9.97; P = 0.04). Over-expression of Ki-67 was strongly correlated with poor survival (χ(2) = 10.44, P = 0.006), but no correlation was found between the expression of p53, EGFR or COX-2 and survival. Multivariate analysis further demonstrated that Ki-67 expression (relative risk = 15.78, 95% CI: 4.25-59.37) could be used as an independent prognostic value for GIST patients. Adjuvant imatinib therapy could improve clinical outcomes in the patients with high risk and intermediate risk of recurrence after complete tumor resections (median survival time: 52 mo vs 37 mo, χ(2) = 7.618, P = 0.006).

CONCLUSION

Our results indicated that the expression of Ki-67 could be used as an independent prognostic factor for GIST patients.

Prognostic significance of PTEN, Ki-67 and CD44s expression patterns in gastrointestinal stromal tumors

AIM: To develop a prognostic approach for gastrointestinal stromal tumors (GISTs) using a cluster of indicators and follow-up information.

METHODS: One hundred and four GISTs that had not been subjected to targeted therapies were collected and classified by NIH risk assessment and anatomic location. By immunohistochemistry, the expressions of PTEN, Ki-67, CD44s matrix metalloproteinase (MMP)-9 and TIMP-1 were detected on tissue microarray. Univariate and multimarker survival analyses were performed and then a COX hazard proportion model was constructed to evaluate a cluster of predictors of GIST.

RESULTS: Our data showed small intestinal GIST are more aggressive than gastric GIST. The NIH risk assessment correlated with disease-free survival for either gastric GIST or small intestinal GIST. Immunohistochemical analysis revealed that Ki-67 labeling indexes (LIs) < 5% predicted higher disease-specific survival (DSS) in gastric and small intestinal GIST. CD44s positivity and PTEN LIs ≥ 50% correlated with higher DSS in gastric GIST. MMP-9 and TIMP-1 had no correlation with survival. Multimarker analysis revealed that the expression pattern of PTEN LIs ≥ 50% combined with Ki-67 LIs < 5% and CD44s positivity reliably predicted favorable outcomes for gastric GIST (P = 0.009), as did the combination of PTEN LIs ≥ 50% and Ki-67 LIs < 5% for small intestinal GIST (P = 0.011). Authors also found that high NIH risk grade was correlated with DSS in patients with gastric GIST and disease-free survival in patients with small intestinal GIST.

CONCLUSION: PTEN LIs ≥ 50%, Ki-67 LIs < 5% and CD44s positivity provides an accurate, favorable prognosis for gastric GIST. PTEN LIs ≥ 50% and Ki-67 LIs < 5% does the same for small intestinal GIST. Ki-67 LIs enhances the NIH assessment.

Clinical proteomics identified ATP-dependent RNA helicase DDX39 as a novel biomarker to predict poor prognosis of patients with gastrointestinal stromal tumor

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal malignancy of the gastrointestinal tract, comprising a wide spectrum from a curable disorder to highly malignant disease. GIST is characterized by tyrosine kinase mutations, and molecular targeting therapies against these abnormal enzymes require prognostic biomarkers. To identify candidate prognostic biomarkers, we examined proteomic features corresponding to metastasis after surgery. Using two-dimensional difference gel electrophoresis with a large format gel, we compared the primary tumor tissues of GIST patients free of metastasis for two years after surgery (eight cases) with those of patients who developed metastasis within one year after surgery (nine cases). We found the intensities of 38 protein spots to differ significantly between the two groups. Mass spectrometric protein identification revealed that these corresponded to 25 unique genes. Immunohistochemical validation demonstrated ATP-dependent RNA helicase DDX39 to be significantly associated with metastasis and poor clinical outcomes in a group of 72 GIST patients. In conclusion, we have established a novel prognostic utility of ATP-dependent RNA helicase DDX39 in GIST.ATP-dependent RNA helicase DDX39, a novel biomarker for GIST likely to be associated with metastatic disease, can identify patients likely to benefit from new therapeutic strategies such as tyrosine kinase inhibitors.

Exon 11 mutations, Ki67, and p16(INK4A) as predictors of prognosis in patients with GIST

Prognostic biomarkers for GIST are under investigation. The aim of this study was to assess whether exon 11 mutations, Ki67, and p16(INK4A) are predictors of prognosis in GIST. Consecutive GIST cases (n=84) had their specimens evaluated for exon 11 mutations and expression of Ki67 and p16(INK4A). Surgical cases were categorized according to NIH and Miettinen's classification, and survival was analyzed from hospital database. GISTs were predominately gastric (45%) and with spindle cell morphology (74%). The risk category was very low or low in 28%, intermediate in 23%, and high in 49%. Exon 11 mutation was identified in 29 (48%) out of 60 cases studied. There were 12 point mutations, 10 deletions, 4 duplications, and 3 double mutations. A third of GISTs had either high Ki67 index (>3%) or negativity for p16(INK4A). In multivariate analysis, independent predictors of mortality were Ki67>3% (HR=7.3; P=0.036) and high mitotic index (HR=10.4; P=0.043). There was no association between exon 11 mutations and survival. This study suggests that Ki67>3% is an independent predictor of poor prognosis in patients with GIST. Exon 11 mutations and negativity for p16(INK4A) need further studies to address the prognostic value.

Role for p16(INK4a) in progression of gastrointestinal stromal tumors of the stomach: alteration of p16(INK4a) network members

Gastrointestinal stromal tumors feature a wide spectrum of biologic behavior, ranging from benign to extremely malignant. To determine the role of p16(INK4a) alteration in progression of gastrointestinal stromal tumors of the stomach, we have investigated protein expression and gene methylation in correlation with clinicopathologic factors and survival. In addition to immunohistochemical analysis of p16(INK4a) in a series of 95 cases, real-time quantitative methylation specific polymerase chain reaction for p16(INK4a) and immunostaining for cyclin D1, cyclin E, pRb, DP-1, E2F-1, and Ki-67 were also evaluated in randomly selected samples. The p16(INK4a) labeling indices ranged from 0% to 74% (median, 21%), demonstrating a significant inverse correlation with size (P = .046). On univariate (P = .003) and multivariate (P = .067) analyses, loss of p16(INK4a) expression increased the likelihood of a poor tumor-related survival. In addition, size (P = .036) and the mitotic index (P = .005) had independent prognostic influence. The p16(INK4a) methylation index, which ranged from 0% to 100% (median, 17%), was significantly higher in larger tumors (P < .001) and in high-risk category lesions (P = .001) and inversely correlated with protein expression. Hierarchical cluster analysis based on expression of p16(INK4a) network members identified 2 clusters in 27 randomly selected tumor samples, containing 11 and 16 tumors each. Former cluster samples demonstrated higher risk category (P = .022), higher p16(INK4a) methylation (P < .001), and more reduced pRb expression (P < .018). In addition, p16(INK4a) network members clustered into 2 groups: (1) showing down-regulated p16(INK4a) protein and up-regulating of both cyclin D1 and DP-1 and (2) down-regulated pRb and up-regulated E2F-1. We conclude that p16(INK4a) alteration has an important role in progression of gastrointestinal stromal tumors of the stomach. Furthermore, the study provides a possible link between regulation of p16(INK4a) network members and gastrointestinal stromal tumors.

Minichromosome maintenance (MCM) and AgNOR proteins expression in desmoid tumours: a tissue microarray analysis

In the present study, nuclear proliferative proteins: MCM2, MCM5, MCM7, Ki-67 and AgNORs expression was assessed in paraffin sections from sporadic desmoid tumours using a tissue microarray (TMA)-based immuno- and histochemistry, respectively. Nuclear expression of MCM7, where the percentage of positive cells was 0.87% (± 1.64) (range 0-5%), was found in 4/20 (20.0%) cases. In 32/32 (100%) of the examined desmoid cases no expression of nuclear proteins MCM2 and MCM5 was detected. Nuclear expression of Ki-67 was observed in 4/21 (19%) cases. Paraffin sections from 30 cases of desmoid tumours were silver-stained to visualize AgNORs. The following AgNOR parameters were calculated: mean AgNOR number per nucleus (N), mean AgNOR area per nucleus, mean AgNOR dot area per nucleus (A), and mean AgNOR content (C = N/A). In the investigated group the mean values of AgNOR parameters were the following number: 4.34 (± 0.11); area: 0.74 μm2 (± 0.19); dot area: 0.18 m2 (± 0.01), and AgNOR content: 23.73 (± 1.85). The mean AgNOR number per nucleus and mean AgNOR content in desmoid tumours were statistically significantly higher as compared to the controls (tonsil tissue) (p<0.001). This study observed low level of MCM7 and Ki-67 and lack of MCM2, MCM5 proteins expression which may explain commonly known low mitotic activity of desmoid tumour cells. The morphology of dots related to AgNORs (number, area) and their morphometric parameters point to elevated transcriptional activity of desmoid cells.

MCM-2 and MCM-5 expression in gastric adenocarcinoma: clinical significance and comparison with Ki-67 proliferative marker

BACKGROUND

Minichromosome maintenance (MCM) proteins are essential components of DNA replication, being related to cell proliferation, and serve as useful biomarkers for cancer screening, surveillance and prognosis. The aim of the present study was to evaluate the clinical significance of MCM-2 and MCM-5 expression in gastric adenocarcinoma in comparison with Ki-67 proliferative marker.

METHODS

MCM-2, MCM-5 and Ki-67 expression was assessed immunohistochemically in 66 tumoral samples of gastric adenocarcinoma patients and was statistically analyzed in relation to clinicopathological characteristics and patient survival.

RESULTS

MCM-2 expression did not show significant associations with any clinicopathological parameters, while Ki-67 expression was merely significantly associated with tumor size (P = 0.0150). MCM-2 and Ki-67 expression were more frequently in intestinal (median values: 67.5 and 60%) compared to diffuse-type (median values: 60 and 45%) gastric adenocarcinoma cases without though reaching statistical significance (P > 0.05). MCM-5 expression was significantly associated with tumor size (P = 0.0295), presence of lymph node metastases (P = 0.0216) and tumor histopathological stage (P = 0.0098). Patients presenting high MCM-5 expression had significantly shorter survival times (log-rank test, P = 0.0042), whereas neither MCM-2 nor Ki-67 expression showed significant prognostic value (log-rank test, P = 0.9618 and P = 0.7174, respectively). In multivariate analysis, patient age, histopathological stage and grade of differentiation, but not MCM-5 expression, were identified as independent prognostic factors (Cox regression analysis, P = 0.0097, P = 0.0195, P = 0.0035 and P = 0.3245, respectively).

CONCLUSIONS

The present study showed that MCM-5 expression was associated with clinicopathological parameters in gastric adenocarcinoma. However, further studies highlighting the distinct impact of the two histopathological types, intestinal and diffuse, are warranted to delineate whether MCMs could be used as diagnostic and prognostic markers in gastric neoplasia.

Predicting malignant potential of gastrointestinal stromal tumors: Role of p16 and E2F1 expression

Altered expression of cell cycle regulatory proteins in GISTs (gastrointestinal stromal tumors) may be the mechanism for their diversity in clinical behavior. The use of these tumorigenetic and cell proliferative proteins may provide an alternative route for follow-up and treatment. The aim of this study was to determine the prognostic relevance of the E2F1 and p16 expression in GISTs. Tissues from 21 cases with GIST were collected retrospectively. Tumor grade was designated according to the consensus system. Immunohistochemistry was done with antibodies against Ki-67, p16, E2F1. For statistical analysis, Ki-67 proliferation index was evaluated in 2 categories: < or =10% and >10%, whereas p16 expression was scored as negative or positive. E2F1 expression cutoff values were tested for risk group variables as >5% and >10%. Correlation between the presence of necrosis, Ki-67 proliferation index, p16, E2F1 expression and the risk grade was determined by Spearman correlation test. Sensitivity and specificity were determined by Fisher exact test with P < or =0.05 considered as significant. High E2F1 expression (over 10%) and high Ki-67 proliferation index (over 10%) correlated significantly with increasing risk grade. There was also a significant correlation between the presence of necrosis and high-risk grade. No correlation was found between the risk grade and p16 expression. Our results suggest that in addition to high Ki-67 proliferation index, high E2F1 expression may also be a useful predictive marker for malignant potential of GISTs.

Loss of chromosome 9p21 and decreased p16 expression correlate with malignant gastrointestinal stromal tumor

AIM: To investigate loss of heterozygosity (LOH) of chromosome 9p21 and the prognostic relevance of p16 expression in gastrointestinal stromal tumor (GIST).

METHODS: Fifty-one GIST patients (30 men and 21 women; median age 59 years; range 29-80 years) treated surgically within a 10-year period were grouped by aggressive behavior risk (17 with very low and low, 14 intermediate, and 20 high risk). GISTs were characterized immunohistochemically and evaluated for LOH of 9p21 by microsatellite analysis at D9S1751, D9S1846, D9S942, and D9S1748. LOH of 9p21 and immunohistochemical expression of p16 protein encoded at 9p21 were correlated with clinicopathological parameters, and the prognostic significance of p16 alterations was evaluated.

RESULTS: Thirty-one (63.3%) cases showed LOH with at least one microsatellite marker. LOH frequency was 37.0% at D9S1751, 37.5% at D9S1846, 42.1% at D9S942, and 24.2% at D9S1748. There was a higher LOH frequency of D9S942 in high-risk than in non-high-risk tumors (P < 0.05, χ² = 4.47). Gender, age, tumor size and site were not correlated with allelic loss. Ninety percent (18/20) of the GIST patients in the high risk group showed LOH with at least one of the 9p21 markers, while 57.1% (8/14) in the intermediate risk group and 33.3% (5/15) in the very low and low risk groups, respectively (P < 0.05, χ² = 12.16). Eight (28.5%) of 31 patients with LOH and 1 (5.6%) of 18 patients without LOH died of the disease during the follow-up period. Loss of p16 protein expression occurred in 41.2%, but in 60% of the high risk group and 23.5% of the very low and low risk groups (P < 0.05, χ² = 4.98). p16 loss was associated with poor prognosis (P < 0.05, χ² = 4.18): the 3- and 5-year overall survival rates were 84.8% and 70.8% for p16-negative and 100% and 92.0% for p16-positive patients, respectively.

CONCLUSION: LOH at 9p21 appears to play an important role in GIST progression; decreased p16 expression in GIST is highly predictive of poor outcome.

Clinicopathological and immunohistochemical features of gastointestinal stromal tumors

PURPOSE

The purpose of this study was to evaluate the clinicopathological features and immunohistochemical features of gastrointestinal stromal tumor (GIST), and specifically the expressions of platelet derived growth factor receptor A (PDGFRA), protein kinase C theta (PKC theta), discovered on GIST-1 (DOG-1), p16 and p27.

MATERIALS AND METHODS

Total 118 patients who underwent surgical resection for GIST at our institution between Jan 1997 and Dec 2007 were retrospectively studied. Immunohistochemical staining for c-kit, PDGFRA, PKC-theta, DOG-1, p16 and p27 was performed on a tissue microarray of the 118 GIST. The clinicopathologic parameters, the disease-free survival (DFS) and the overall survival rate were analyzed along with immunohistochemistry.

RESULTS

The immunohistochemical stains for c-kit, CD34, PKC-theta, PDGFRA, DOG-1, p16 and p27 were positive in 89.8%, 72.0%, 56.8%, 94.9%, 90.7%, 69.5% and 44.1% of the tumor samples, respectively. The immunohistochemical expression of c-kit was strongly correlated with PKC-theta (p=0.000), DOG-1 (p=0.000) and CD34 (p=0.002). The DFS rate was significantly decreased for the patients with peritoneal GIST, high risk GIST, ≥10 cm-sized GIST, ≥10 mitoses/50 high power fields (HPFs) and p16 positivity (p=0.001, p=0.004, p=0.001, p=0.003 and p=0.028). GISTs ≥10 cm, epithelioid tumor cell type, and c-kit, and DOG-1 negativity were significantly associated with shorter period of overall survival (p=0.048, p=0.006, p=0.000 and p=0.000).

CONCLUSION

The expression of p16 and no expression of c-kit and DOG-1 in GISTs, as well as peritoneal tumor site, high risk group, large tumor size, epithelioid tumor cell type and numerous mitoses, may be potentially prognostic factors for predicting worse outcome for patients who suffer from GIST.

Duodenal gastrointestinal stromal tumor: clinical, pathologic, immunohistochemical characteristics, and surgical prognosis

OBJECTIVE

Gastrointestinal stromal tumors (GISTs) occur rarely in the duodenum. The characteristics of duodenal GIST have not been well clarified. The aim of this study is to clarify the characteristics and surgical prognosis of patients with primary duodenal GIST.

METHODS

Data of patients with surgically treated primary duodenal GIST were retrospectively analyzed. Immunohistochemical expressions of p53, p16, and Ki-67 were evaluated to explain the prognosis.

RESULTS

Compared with gastric or small intestinal GISTs in historical studies, duodenal GISTs had a relatively smaller size, lower mitotic count, lower Ki-67 LI, lower p16 loss, and similar p53 expression. The 1- and 3-year recurrence-free survival rates of patients with complete resection were 100 and 95.2%.

CONCLUSION

Patients with completely resected primary duodenal GIST seem to have a more favorable prognosis. This may be related to the different expressions of some immunohistological makers compared with GISTs of other locations.

High density DNA array analysis reveals distinct genomic profiles in a subset of gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) generally harbor activating mutations in KIT or platelet-derived growth facter receptor (PDGFRA). Mutations in these receptor tyrosine kinases lead to dysregulation of downstream signaling pathways that contribute to GIST pathogenesis. GISTs with KIT or PDGFRA mutations also undergo secondary cytogenetic alterations that may indicate the involvement of additional genes important in tumor progression. Approximately 10-15% of adult and 85% of pediatric GISTs do not have mutations in KIT or in PDGFRA. Most mutant adult GISTs display large-scale genomic alterations, but little is known about the mutation-negative tumors. Using genome-wide DNA arrays, we investigated genomic imbalances in a set of 31 GISTs, including 10 KIT/PDGFRA mutation-negative tumors from nine adults and one pediatric case and 21 mutant tumors. Although all 21 mutant GISTs exhibited multiple copy number aberrations, notably losses, eight of the 10 KIT/PDGFRA mutation-negative GISTs exhibited few or no genomic alterations. One KIT/PDGFRA mutation-negative tumor exhibiting numerous genomic changes was found to harbor an alternate activating mutation, in the serine-threonine kinase BRAF. The only other mutation-negative GIST with significant chromosomal imbalances was a recurrent metastatic tumor found to harbor a homozygous deletion in chromosome arm 9p. Similar findings in several KIT-mutant GISTs identified a minimal overlapping region of deletion of approximately 0.28 Mbp in 9p21.3 that includes only the CDKN2A/2B genes, which encode inhibitors of cell-cycle kinases. These results suggest that GISTs without activating kinase mutations, whether pediatric or adult, generally exhibit a much lower level of cytogenetic progression than that observed in mutant GISTs.

Homozygous deletion of MTAP gene as a poor prognosticator in gastrointestinal stromal tumors

PURPOSE

Chromosome 9 is frequently deleted in high-risk gastrointestinal stromal tumors (GISTs), whereas its specific tumor suppressor genes (TSGs) are less understood. We did an integrative study of MTAP gene at 9p21 to analyze its implication in GISTs.

EXPERIMENTAL DESIGN

To search TSGs on chromosome 9, we used ultrahigh-resolution array comparative genomic hybridization to profile DNA copy number alterations of 22 GISTs, with special attention to MTAP gene. MTAP immunoexpression was assessable for 306 independent GISTs on tissue microarrays, with 146 cases analyzed for MTAP homozygous deletion, 181 for mutations of KIT and PDGFRA receptor tyrosine kinase genes, and 7 for MTAP hypermethylation.

RESULTS

Array comparative genomic hybridization identified 11 candidate TSGs on 9p and six on 9q. MTAP and/or CDKN2A/CDKN2B at 9p21.3 were deleted in one intermediate-risk (11%) and seven high-risk (70%) GISTs with two cases homozygously codeleted at both loci. MTAP homozygous deletion, present in 25 of 146 cases, was highly associated with larger size and higher mitotic rate, Ki-67 index, and risk level (all P < 0.01) but not with receptor tyrosine kinase genotypes. Whereas MTAP homozygous deletion correlated with MTAP protein loss (P < 0.001), 7 of 30 GISTs without MTAP expression did not show homozygous deletion, including three MTAP-hypermethylated cases. MTAP homozygous deletion was univariately predictive of decreased disease-free survival (P < 0.0001) and remained multivariately independent (P = 0.0369, hazard ratio = 2.166), together with high-risk category (P < 0.0001), Ki-67 index >5% (P = 0.0106), and nongastric location (P = 0.0416).

CONCLUSIONS

MTAP homozygous deletion, the predominant mechanism to deplete protein expression, is present in 17% of GISTs. It correlates with important prognosticators and independently predicts worse outcomes, highlighting the role in disease progression.

Ezrin overexpression in gastrointestinal stromal tumors: an independent adverse prognosticator associated with the non-gastric location

Ezrin, a member of the ezrin-radixin-moesin family, acts as a link between the cell membrane and actin cytoskeleton to integrate cell adhesion-mediated signaling. It implicates tumor progression, metastatic dissemination, and adverse outcomes in several cancer types, including pediatric and adult sarcomas. Although ezrin upregulation was shown by cDNA expression profiling, no study has systematically evaluated the significance of ezrin expression in a large cohort of gastrointestinal stromal tumors (GISTs). Ezrin immunostaining was carried out on tissue microarrays of primary GISTs and assessable in 347 cases, 188 of which were successfully evaluated for mutation variants of KIT and PDGFRA receptor tyrosine kinase (RTK) genes by sequencing with or without screening by denatured high-performance liquid chromatography. These GISTs with known RTK genotypes were dichotomized into two prognostically different groups. The endogenous expression and phosphorylation of ezrin in GIST cell lines were analyzed by western blotting. By immunohistochemistry, ezrin overexpression was present in 66% of GISTs and significantly associated with the non-gastric location (P=0.002) and decreased disease-free survival (P=0.032, univariately). However, it was not related to the National Institute of Health (NIH) risk category, Ki-67 labeling index, RTK genotypes, and other variables. In multivariate analyses, ezrin overexpression remained independently predictive of adverse outcome (P=0.008, risk ratio=2.363), together with Ki-67 labeling index >5% (P<0.001, risk ratio=3.581), high-risk category (P<0.001, risk ratio=2.156), and the non-gastric location (P=0.029, risk ratio=1.899). Despite the variation in the ezrin expression level, phosphorylated ezrin at threonine(567) was only detectable in GIST882 and GIST48 cells, but not in colonic smooth muscle cells. In conclusion, ezrin is frequently overexpressed in GISTs, especially those arising from the non-gastric sites. Given that its impact is independent of the NIH risk category, cell proliferation, and tumor location, ezrin immunoreactivity represents a valuable prognostic adjunct of GISTs, suggesting a causative role in conferring an aggressive phenotype.

Development and validation of a prognostic nomogram for recurrence-free survival after complete surgical resection of localised primary gastrointestinal stromal tumour: a retrospective analysis

BACKGROUND

Adjuvant imatinib mesylate prolongs recurrence-free survival (RFS) after resection of localised primary gastrointestinal stromal tumours (GIST). We aimed to develop a nomogram to predict RFS after surgery in the absence of adjuvant therapy to help guide patient selection for adjuvant imatinib therapy.

METHODS

A nomogram to predict RFS based on tumour size (cm), location (stomach, small intestine, colon/rectum, or other), and mitotic index (<5 or > or =5 mitoses per 50 high-power fields) was developed from 127 patients treated at Memorial Sloan-Kettering Cancer Center (MSKCC), New York, NY, USA. The nomogram was tested in patients from the Spanish Group for Research on Sarcomas (GEIS; n=212) and the Mayo Clinic, Rochester, MN, USA (Mayo; n=148). The nomogram was assessed by calculating concordance probabilities and testing calibration of predicted RFS with observed RFS. Concordance probabilities were also compared with those of three commonly used staging systems.

FINDINGS

The nomogram had a concordance probability of 0.78 (SE 0.02) in the MSKCC dataset, and 0.76 (0.03) and 0.80 (0.02) in the validation cohorts. Nomogram predictions were well calibrated. Inclusion of tyrosine kinase mutation status in the nomogram did not improve its discriminatory ability. Concordance probabilities of the nomogram were better than those of the two NIH staging systems (0.76 [0.03] vs 0.70 [0.04, p=0.04] and 0.66 [0.04, p=0.01] in the GEIS validation cohort; 0.80 [0.02] vs 0.74 [0.02, p=0.04] and 0.78 [0.02, p=0.05] in the Mayo cohort) and similar to those of the AFIP-Miettinen staging system (0.76 [0.03] vs 0.73 [0.004, p=0.28] in the GEIS cohort; 0.80 [0.02] vs 0.76 [0.003, p=0.09] in the Mayo cohort). Nomogram predictions of RFS seemed better calibrated than predictions made with the AFIP-Miettinen system.

INTERPRETATION

The nomogram accurately predicts RFS after resection of localised primary GIST and could be used to select patients for adjuvant imatinib therapy.

Scoring of p16(INK4a) immunohistochemistry based on independent nuclear staining alone can sufficiently distinguish between endocervical and endometrial adenocarcinomas in a tissue microarray study

Endocervical adenocarcinomas and endometrial adenocarcinomas are malignancies that affect uterus; however, their biological behaviors are quite different. This distinction has clinical significance, because the appropriate therapy may depend on the site of tumor origin. The purpose of this study is to evaluate four different scoring methods of p16(INK4a) immunohistochemical staining in distinguishing between primary endocervical adenocarcinomas and endometrial adenocarcinomas from limited sizes of tissue specimens. A tissue microarray was constructed using formalin-fixed, paraffin-embedded tissue from hysterectomy specimens, including 14 endocervical adenocarcinomas and 21 endometrial adenocarcinomas. Tissue array sections were immunostained with a commercially available antibody of p16(INK4a). Avidin-biotin complex method was used for antigens visualization. The staining intensity and area extent of the immunohistochemistry was evaluated using the semiquantitative scoring system. Of the four scoring methods for p16(INK4a) expression, Method Nucleus, Method Dominant Cytoplasm or Nucleus, and Method Mean of Cytoplasm plus Nucleus showed significant (P values <0.05), but Method Cytoplasm did not show significant (P=0.432), frequency distinction between endocervical adenocarcinomas and endometrial adenocarcinomas. In addition, Method Mean of Cytoplasm plus Nucleus had the highest overall accuracy rate (80%) for diagnostic distinction among these four score-counting methods. According to the data in this tissue microarray study, Method Nucleus is the most convenient and efficient method to distinguish between endocervical adenocarcinomas and endometrial adenocarcinomas. Although Method Dominant Cytoplasm or Nucleus as well as Method Mean of Cytoplasm plus Nucleus also revealed statistically significant results, they are relatively more inconvenient due to complicated score calculating means on the basis of mixed cytoplasmic and nuclear p16(INK4a) expressions. Method Cytoplasm is of no use in the diagnostic distinction between endocervical adenocarcinomas and endometrial adenocarcinomas.

Progesterone receptor does not improve the performance and test effectiveness of the conventional 3-marker panel, consisting of estrogen receptor, vimentin and carcinoembryonic antigen in distinguishing between primary endocervical and endometrial adenocarcinomas in a tissue microarray extension study

Objective

Endocervical adenocarcinomas (ECA) and endometrial adenocarcinomas (EMA) are uterine malignancies that have differing biological behaviors. The choice of an appropriate therapeutic plan rests on the tumor's site of origin. In this study, we propose to evaluate whether PR adds value to the performance and test effectiveness of the conventional 3-marker (ER/Vim/CEA) panel in distinguishing between primary ECA and EMA.

Methods

A tissue microarray was constructed using paraffin-embedded, formalin-fixed tissues from 38 hysterectomy specimens, including 14 ECA and 24 EMA. Tissue microarray (TMA) sections were immunostained with 4 antibodies, using the avidin-biotin complex (ABC) method for antigen visualization. The staining intensity and extent of the immunohistochemical (IHC) reactions were appraised using a semi-quantitative scoring system.

Results

The three markers (ER, Vim and CEA) and their respective panel expressions showed statistically significant (p < 0.05) frequency differences between ECA and EMA tumors. Although the additional ancillary PR-marker also revealed a significant frequency difference (p < 0.05) between ECA and EMA tumors, it did not demonstrate any supplementary benefit to the 3-marker panel.

Conclusion

According to our data, when histomorphological and clinical doubt exists as to the primary site of origin, we recommend that the conventional 3-marker (ER/Vim/CEA) panel is easier, sufficient and appropriate to use in distinguishing between primary ECA and EMA. Although the 4-marker panel containing PR also reveals statistically significant results, the PR-marker offers no supplemental benefit to the pre-existing 3-marker (ER/Vim/CEA) panel in the diagnostic distinction between ECA and EMA.

Scoring mechanisms of p16INK4a immunohistochemistry based on either independent nucleic stain or mixed cytoplasmic with nucleic expression can significantly signal to distinguish between endocervical and endometrial adenocarcinomas in a tissue microarray study

Background

Endocervical adenocarcinomas (ECAs) and endometrial adenocarcinomas (EMAs) are malignancies that affect uterus; however, their biological behaviors are quite different. This distinction has clinical significance, because the appropriate therapy may depend on the site of tumor origin. The purpose of this study is to evaluate 3 different scoring mechanisms of p16^INK4a immunohistochemical (IHC) staining in distinguishing between primary ECAs and EMAs.

Methods

A tissue microarray (TMA) was constructed using formalin-fixed, paraffin-embedded tissue from hysterectomy specimens, including 14 ECAs and 24 EMAs. Tissue array sections were immunostained with a commercially available antibody of p16^INK4a. Avidin-biotin complex (ABC) method was used for antigens visualization. The staining intensity and area extent of the IHC reactions was evaluated using the semi-quantitative scoring system. The 3 scoring methods were defined on the bases of the following: (1) independent cytoplasmic staining alone (Method C), (2) independent nucleic staining alone (Method N), and (3) mean of the sum of cytoplasmic score plus nucleic score (Method Mean of C plus N).

Results

Of the 3 scoring mechanisms for p16^INK4a expression, Method N and Method Mean of C plus N showed significant (p-values < 0.05), but Method C showed non-significant (p = 0.245) frequency differences between ECAs and EMAs. In addition, Method Mean of C plus N had the highest overall accuracy rate (81.6%) for diagnostic distinction among these 3 scoring methods.

Conclusion

According to the data characteristics and test effectiveness in this study, Method N and Method Mean of C plus N can significantly signal to distinguish between ECAs and EMAs; while Method C cannot do. Method Mean of C plus N is the most promising and favorable means among the three scoring mechanisms.

Heat shock protein 90 overexpression independently predicts inferior disease-free survival with differential expression of the alpha and beta isoforms in gastrointestinal stromal tumors

PURPOSE

Most gastrointestinal stromal tumors harbor a mutated KIT or PDGFRA receptor tyrosine kinase (RTK). Heat shock protein 90 (Hsp90) is a chaperone mediating the folding and stabilization of many oncoproteins, including KIT. An Hsp90 inhibitor, 17-AAG, can attenuate KIT activation and proliferation of gastrointestinal stromal tumor cell lines. We further evaluated Hsp90 immunoexpression and the difference between alpha and beta isoforms in gastrointestinal stromal tumor specimens.

EXPERIMENTAL DESIGN

Hsp90 immunostain was assessable in 306 cases on tissue microarrays of primary gastrointestinal stromal tumors and correlated with various variables and disease-free survival (DFS). RTK mutation variants, confirmed in 142 cases by sequencing with or without precedent denaturing high pressure liquid chromatography screening, were dichotomized into two prognostically different groups. Differential expression of transcript and protein isoforms was measured by real-time reverse transcription-PCR and Western blotting in 16 and 6 cases, respectively.

RESULTS

Hsp90 overexpression (55%) significantly correlated with larger size, nongastric location, higher mitotic count and NIH risk level, Ki-67 overexpression (all P < or = 0.001), and unfavorable RTK genotypes (P = 0.020). It strongly portended inferior DFS univariately (P < 0.0001) and remained independent in multivariate analysis (P = 0.031; risk ratio, 2.44), along with high-risk category, Ki-67 overexpression, and old age. For both mRNA and protein, Hsp90beta was more abundant than Hsp90alpha, whereas the latter was significantly higher in high-risk cases.

CONCLUSIONS

Hsp90 overexpression represents a poor prognosticator that correlates with several adverse parameters, highlighting its role in disease progression and alternative therapy for high-risk, imatinib-resistant gastrointestinal stromal tumors. Hsp90alpha seems more relevant to the intrinsic aggressiveness of gastrointestinal stromal tumors, albeit less abundant than Hsp90beta.

p16 expression differentiates high-risk gastrointestinal stromal tumor and predicts poor outcome

Gastrointestinal stromal tumors (GISTs) are characterized by alterations in genes involved in cell cycle regulation. Although p16 (INK4A) have been extensively investigated in GISTs, there are still discrepancies regarding its prognostic value. Therefore, we evaluated the clinical occurrence, diagnostic and prognostic value of p16 staining in GIST. One hundred one patients (54 women and 47 men) with a mean age of 64.1 years (range, 17-94 years) were surgically treated for a GIST within a 10-year period. Of these patients, 28 (28%) were affected by metastases (mean follow-up, 4.5 years). In 36 patients (36%), GIST occurred coincidentally with other malignancies. Expression of c-kit was confirmed in 97 GIST patients (96%). In patients with high-risk GIST, the expression of p16 expression was highly predictive for poor prognosis, i.e., the development of recurrence or metastases (P = .006) and poor survival (P = .004). In addition, the expression of p16 was highly predictive for reduction of the survival in patients who were affected by metastases or recurrence (P = .041). The disease-specific and disease-free 1-, 3-, and 5-year survival rate was 96%, 90%, and 85% and 81%, 77%, and 72%, respectively. Primary tumor state, tumor size, and high-risk classification were confirmed as relevant predictors for unfavorable prognosis in GIST (P < .001). Our results indicate that in high-risk GIST and in patients with recurrence or metastases, the expression of p16 is highly predictive for poor outcome. Thus, in addition to high-risk classification, p16 expression might be an indicator for "very high risk GIST."

Drug Insight: gastrointestinal stromal tumors (GIST)--the solid tumor model for cancer-specific treatment

We are living in an exciting era in the treatment of cancer, using drugs that target specific proteins rather than agents that cause more general cytotoxic effects. The identification of proteins and signal transduction pathways that play crucial roles in the pathogenesis of cancer has allowed treatments to be designed that target these tumor-driven events. Gastrointestinal stromal tumors (GIST) are rare mesenchymal tumors and were among the first solid tumor types for which such a novel treatment (in this case imatinib) became available. The tyrosine kinase inhibitor imatinib targets the human KIT receptor and the platelet-derived growth factor receptor-alpha. This drug exhibits impressive antitumor effects against GIST and has become the first-line therapy for advanced disease. Major insights into the mechanism of action of this drug, drug resistance, and patient management issues have been gleaned. Additionally, new drugs developed for the treatment of GIST have been identified. As a consequence, lessons learned from GIST are widely applicable to other tumor entities, thereby rendering GIST the paradigm of solid tumors treated with tyrosine kinase inhibitors. This Review discusses the pathogenesis of GIST, treatment strategies, mechanisms accounting for drug resistance, and potential future perspectives.