Microsatellite DNA alterations of gastrointestinal stromal tumors are predictive for outcome

KCTD12 is negatively regulated by Kit in gastrointestinal stromal tumors

Our group has previously demonstrated that pfetin, encoded by the KCTD12 gene, is a strong prognostic biomarker for gastrointestinal stromal tumors (GISTs). However, the underlying mechanisms that control pfetin expression remain unknown. To elucidate the regulatory mechanisms of KCTD12 in GIST, in addition to a possible association between KCTD12 alterations and protein expression, we examined 76 patients with GISTs for KCTD12 mutations by PCR-direct sequence, and compared these results with clinicopathologic data. The function of pfetin in GIST progression was also revealed using GIST T1 cells. In this series, pfetin expression was not observed in 15 cases, and loss of pfetin expression was associated with higher mitotic rate (>5/50HPFs: p = 0.029). There was also a trend between presence of necrosis and loss of pfetin expression but this was not statistically significant (p = 0.09). KCTD12 mutations were frequently observed in 22 out of 76 GISTs (28.9%); however, they did not affect protein expression and were not associated with patients' prognosis. KCTD12 in vitro knockdown resulted in the accelerated growth of GIST T1 cells, confirming that pfetin functions as a tumor suppressor. KIT knockdown significantly inhibited cellular growth and upregulated the expression of pfetin at both the mRNA and protein level. These findings suggest that GISTs with loss of pfetin expression has proliferative advantage and that higher pfetin expression in GISTs may be indicative of lower expression levels of KIT. This relationship confirms that pfetin is a useful prognostic marker in GISTs.

[Gastrointestinal stromal tumors: surgical treatment and targeted therapy]

AIM

To improve surgical and complex treatment of patients with gastrointestinal stromal tumors (GIST).

MATERIAL AND METHODS

Our analysis included 97 GIST patients who were at Petrovsky Russian Research Center of Surgery and Moscow City Oncological Hospital #62 from January 2006 to September 2016.

RESULTS

Advisability of surgery for GIST patients was confirmed. We have assessed surgical outcomes, defined the indications for adjuvant targeted therapy depending on GIST prognostic risk and additional factors for unfavorable course of disease.

CONCLUSION

It was concluded that surgical treatment is preferred for patients with resectable GISTs. Adjuvant therapy is indicated in patients with high risk of progression if mutations indicating tumor sensitivity to the drugs are revealed. Adjuvant targeted therapy is not indicated in patients with low and very low risk of progression.

Loss expression of micro ribonucleic acid (miRNA)-200c induces adverse post-surgical prognosis of advanced stage non-small cell lung carcinoma and its potential relationship with ETAR messenger RNA

BACKGROUND

Non-small cell lung cancer (NSCLC) is the leading cause of cancer mortality worldwide. As micro ribonucleic acid (miRNA)-200 and ETAR may play an essential role in the process of epithelial to mesenchymal transition (EMT) simultaneously, the purpose of this study was to detect the expression of miRNA-200c and ETAR messenger (m)RNA and assess their prognostic significance in early stage NSCLC.

METHODS

Our study included 78 advanced stage (IIB, IIIA, IIIB) NSCLC patients. All patients were smokers. Using quantitative reverse transcriptase polymerase chain reaction analysis, we detected the expression of miRNA-200c and ETAR mRNA and assessed their correlation by χ(2) test. Time to progression was used as the recurrent index and was assessed by univariate and multivariate analysis in the Cox hazard model.

RESULTS

Both miRNA-200c and ETAR mRNA expression are associated with N stage and tumor node metastasis (TNM) stage in a series of advanced NSCLC patients. Among N stage and TNM stage patients, significant differences were found in IIB (P = 0.0126), IIIB (P = 0.0107) and N0 (P = 0.0023) and in N1 + N2 groups (P = 0.0133). Using both univariate and multivariate survival analyses, we found that miRNA-200c (hazard ratio [HR] = 0.352, 95% confidence interval [CI]: 0.187-0.662) and ETAR mRNA (HR = 2.500 95% CI: 1.345-4.647) were independent prognostic factors, independent of TNM stage (HR = 2.414, 95% CI: 1.600-3.642) and differentiation (HR = 1.530, 95% CI: 1.050-2230).

CONCLUSIONS

miRNA-200c induces an expedient surgical survival, whereas ETAR mRNA has the reverse prognosis in advanced stage NSCLC patients. A potential relationship exists in that miRNA-200c targets ETAR mRNA during EMT.

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.

Gastrointestinal stromal tumors: what do we know now?

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the GI tract, arising from the interstitial cells of Cajal, primarily in the stomach and small intestine. They manifest a wide range of morphologies, from spindle cell to epithelioid, but are immunopositive for KIT (CD117) and/or DOG1 in essentially all cases. Although most tumors are localized at presentation, up to half will recur in the abdomen or spread to the liver. The growth of most GISTs is driven by oncogenic mutations in either of two receptor tyrosine kinases: KIT (75% of cases) or PDGFRA (10%). Treatment with tyrosine kinase inhibitors (TKIs) such as imatinib, sunitinib, and regorafenib is effective in controlling unresectable disease; however, drug resistance caused by secondary KIT or PDGFRA mutations eventually develops in 90% of cases. Adjuvant therapy with imatinib is commonly used to reduce the likelihood of disease recurrence after primary surgery, and for this reason assessing the prognosis of newly resected tumors is one of the most important roles for pathologists. Approximately 15% of GISTs are negative for mutations in KIT and PDGFRA. Recent studies of these so-called wild-type GISTs have uncovered a number of other oncogenic drivers, including mutations in neurofibromatosis type I, RAS genes, BRAF, and subunits of the succinate dehydrogenase complex. Routine genotyping is strongly recommended for optimal management of GISTs, as the type and dose of TKI used for treatment is dependent on the mutation identified.

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.

Clinical value of loss of heterozygosity in serum microsatellite DNA of patients with gastrointestinal stromal tumors

GOALS

To study the role of loss of heterozygosity (LOH) in serum microsatellite DNA of patients with gastrointestinal stromal tumors (GIST).

BACKGROUND

In GIST, tumor markers from peripheral blood are missing.

STUDY

Seventy-eight patients (59 GIST, 13 leiomyomas, 2 leiomyosarcomas, and 4 schwannomas) underwent resection at our institute between 1985 and 2006. Thirty-three preoperative sera (26 GIST and 7 non-GIST) and 62 postoperative sera (47 GIST and 15 non-GIST) were available and tested for alterations in 12 representative microsatellite loci on chromosomes 22, 17, 13, 9, and 3, using fluorescence-based automated capillary electrophoresis by ABI Prism. Survival was calculated with Kaplan-Meier plots.

RESULTS

Seventeen out of 26 GIST patients had a positive preoperative serum LOH score (> or =2 LOH, sensitivity 65.4%), and 6 out of 7 non-GIST patients had a negative score (< or =1 LOH, specificity 85.7%, P=0.030, Fisher exact test). Serum LOH in GIST were strongly correlated with Fletcher risk groups (P=0.016, chi test). All metastasized GIST (7/7) showed > or =2 LOH preoperatively. Postoperative sensitivity and specificity of LOH analysis for prediction of relapse in 47 GIST was 75.0% and 64.1%, respectively. After a median observation time of 51.3 months (95% confidence interval, 39.4-61.4), LOH in serum significantly predicted overall survival (P=0.007, log-rank test).

CONCLUSIONS

LOH serum analysis in GIST may play a role as a noninvasive, differential diagnostic, prognostic, and monitoring marker in the clinical routine.

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.

Thy-1 as a potential novel diagnostic marker for gastrointestinal stromal tumors

PURPOSE

Only few immunohistochemical markers besides c-kit exist for gastrointestinal stromal tumors (GISTs). Thy-1, a cell-surface glycoprotein, is a marker for several types of stem cells and particularly for neuronal precursor cells. The aim of this study was to determine Thy-1 expression in GISTs.

MATERIALS AND METHODS

Fifty-seven surgically resected and paraffin-embedded GIST samples were analyzed by immunohistochemistry with peroxidase method for Thy-1 molecule.

RESULTS

Thy-1 was detected in the majority of 57 GIST samples (54 out of 57 patients, 95%). All samples were c-kit positive and 90% were CD34 positive. All three Thy-1 negative samples were CD34 positive, had a low proliferative index (Ki-67 <or= 10%) and were located in the upper gastrointestinal tract (one in esophagus and two in the stomach). As a tendency, Thy-1 negative patients had a better prognosis, although not reaching level of significance due to low numbers.

CONCLUSIONS

Thy-1 is expressed in the majority of GISTs, suggesting a novel, additional standard marker for identifying GIST. Future studies should focus on the role of Thy-1 in the pathogenesis of GIST and subsequently on its potential to act as a molecular target for adjuvant therapy with new molecular antitumor agents.

Adult human sarcomas. II. Medical oncology

Human sarcoma cells can be killed by radio- and chemotherapy, but tumor cells acquiring resistance frequently kill the patient. A keen understanding of the intracellular course of oncogenic cascades leads to the discovery of small molecular inhibitors of the involved phosphorylated kinases. Targeted therapy complements chemotherapy. Oncogene silencing is feasible by small interfering RNA. The restoration of some of the mutated or deleted tumor-suppressor genes (p53, Rb, PTEN, hSNF, INK/ARF and WT) by demethylation or reacetylation of their histones has been accomplished. Genetically engineered or naturally oncolytic viruses selectively lyse tumors and leave healthy tissues intact. Adeno- or retroviral vectors deliver genes of immunological costimulators, tumor antigens, chemo- or cytokines and/or tumor-suppressor proteins into tumor (sarcoma) cells. Suicide gene delivery results in apoptosis induction. Genes of enzymes that target prodrugs as their substrates render tumor cells highly susceptible to chemotherapy, with the prodrug to be targeted intracellularly. It will be combinations of sophisticated surgical removal of the nonencapsulated and locally invasive primary sarcomas, advanced forms of radiotherapy to the involved sites and immunotherapy with sarcoma vaccines that will cure primary sarcomas. Adoptive immunotherapy with immune lymphocytes will be operational in metastatic disease only when populations of regulatory T cells are controlled. Targeted therapy with small molecular inhibitors of oncogene cascades, the driving forces of sarcoma cells, alteration of the tumor stroma from a supportive to a tumor-hostile environment, reactivation or replacement of wild-type tumor-suppressor genes, and radio-chemotherapy (with much reduced toxicity) will eventually accomplish the cure of metastatic sarcomas.