SMYD2 aggravates gastrointestinal stromal tumor via upregulation of EZH2 and downregulation of TET1

SMYD2, as an oncogene, has been involved in multiple types of cancer, but the potential role of SMYD2 in gastrointestinal stromal tumors (GIST) remains enigmatic and requires further investigation. Hence, this study was conducted with the main objective of analyzing the effect of SMYD2 on GIST. GIST and adjacent normal tissues were collected from 46 patients with GIST where the expression of EZH2, SMYD2, and TET1 was determined, followed by the analysis of their interactions. The functional role of SMYD2 in cell biological functions was determined using a loss-of-function assay in GIST-T1 cells. Nude mouse xenograft experiments were performed to verify the role of the SMYD2/EZH2/TET1 axis in GIST in vivo. EZH2 was upregulated in GIST tissues and cell lines, which was positively correlated with SMYD2 expression and inversely correlated with TET1 expression in GIST tissues. EZH2 silencing due to SMYD2 inhibition reduced GIST-T1 cell proliferation and accelerated cell senescence. EZH2 repressed TET1 expression by promoting H3K27me3 methylation in the TET1 promoter region. TET1 inhibition reversed the effect of EZH2 silencing on the biological functions of GIST-T1 cells. In vivo data further revealed the promoting effect of SMYD2 on the progression of GIST by regulating the EZH2/TET1 axis. Overall, this study demonstrates that SMYD2 can increase EZH2 expression while suppressing TET1 expression, thus accelerating GIST, and creating new treatment opportunities for GIST.

Prognostic value of tumor necrosis in gastrointestinal stromal tumor: A meta-analysis

BACKGROUND AND AIMS

There is currently no consensus regarding the influence of tumor necrosis on the prognosis of gastrointestinal stromal tumors (GISTs). Therefore, we conducted a meta-analysis to determine the prognostic role of tumor necrosis in patients with GIST.

METHODS

PubMed, Embase, and Web of Science electronic databases were searched from their inception to March 2018. Studies reporting data on the relationship between tumor necrosis and GIST prognosis were eligible. The measure of the effect of interest was the odds ratios (ORs) with 95% confidence intervals (CIs). This study has been registered in the Prospero (number CRD42018096036).

RESULTS

In total, 18 studies including 2320 patients were identified. The total odds of tumor necrosis were associated with a poor GIST prognosis (OR = 5.54, 95% CI = 4.39-6.99). Subgroup analysis of different observed outcomes indicated that tumor necrosis was associated with a decreased disease-free survival (OR = 7.08, 95% CI = 4.78-10.49), recurrence-free survival (OR = 3.96, 95% CI = 2.48-6.32), and overall survival (OR = 4.29, 95% CI = 2.02-9.13). In addition, any tumor site, tumor size, follow-up time, ethnicity, different outcomes of GIST, and different degrees of positive staining of immunohistochemical markers subgroups showed a significantly increased risk of a poor prognosis.

CONCLUSIONS

Tumor necrosis may likely predict a poorer prognosis for GIST. However, further well-designed prospective studies with large sample size are required in the future.

Expression of cell cycle regulators and frequency of TP53 mutations in high risk gastrointestinal stromal tumors prior to adjuvant imatinib treatment

Despite of multitude investigations no reliable prognostic immunohistochemical biomarkers in GIST have been established so far with added value to predict the recurrence risk of high risk GIST besides mitotic count, primary location and size. In this study, we analyzed the prognostic relevance of eight cell cycle and apoptosis modulators and of TP53 mutations for prognosis in GIST with high risk of recurrence prior to adjuvant treatment with imatinib. In total, 400 patients with high risk for GIST recurrence were randomly assigned for adjuvant imatinib either for one or for three years following laparotomy. 320 primary tumor samples with available tumor tissue were immunohistochemically analyzed prior to treatment for the expression of cell cycle regulators and apoptosis modulators cyclin D1, p21, p16, CDK4, E2F1, MDM2, p53 and p-RB1. TP53 mutational analysis was possible in 245 cases. A high expression of CDK4 was observed in 32.8% of all cases and was associated with a favorable recurrence free survival (RFS), whereas high expression of MDM2 (12.2%) or p53 (35.3%) was associated with a shorter RFS. These results were independent from the primary KIT or PDGFRA mutation. In GISTs with higher mitotic counts was a significantly increased expression of cyclin D1, p53 and E2F1. The expression of p16 and E2F1 significantly correlated to a non-gastric localization. Furthermore, we observed a significant higher expression of p21 and E2F1 in KIT mutant GISTs compared to PDGFRA mutant and wt GISTs. The overall frequency of TP53 mutations was low (n = 8; 3.5%) and could not be predicted by the immunohistochemical expression of p53. In summary, mutation analysis in TP53 plays a minor role in the subgroup of high-risk GIST before adjuvant treatment with imatinib. Strong expression of MDM2 and p53 correlated with a shorter recurrence free survival, whereas a strong expression of CDK4 correlated to a better recurrence free survival.

Identification of Recurrence-Predictive Indicators in Stage I Colorectal Cancer

BACKGROUND

Patients with stage I colorectal cancer (CRC) rarely experience recurrences; therefore, few risk factors for recurrence are known. This study was designed to evaluate oncologic outcomes of patients with stage I CRC and to identify risk factors for recurrence after curative surgery.

METHODS

A retrospective cohort of 860 patients from a single institution who underwent curative surgery for stage I CRC between July 1995 and June 2010 was enrolled. Patients who were diagnosed with hereditary, synchronous, or metachronous cancer and those who received preoperative chemoradiotherapy were excluded. Patients from whom fewer than 12 lymph nodes were retrieved were also excluded.

RESULTS

The 860 patients included 402 (46.7%) with colon tumors and 458 (53.3%) with rectal tumors. Thirty-five patients (4.1%) experienced recurrences; local and systemic recurrence rates were 1.1 and 3.0%, respectively. The 5-year overall survival and recurrence-free survival (RFS) rates were 93.5 ± 0.8% and 95.7 ± 0.8%, respectively. Multivariate analysis showed that preoperative serum carcinoembryonic antigen (CEA) concentration ≥6 ng/mL (hazard ratio [HR] 3.354, 95% confidence interval [CI] 1.373-8.195, p = 0.008) and lymphovascular invasion (LVI) (HR 2.676, 95% CI 1.097-6.531, p = 0.031) were independent risk factors for RFS.

CONCLUSIONS

The overall recurrence rate among patients with stage I CRC after curative surgery was 4.1%. Elevated serum CEA and LVI were significantly associated with recurrence. Large-scale, multicenter studies are needed to confirm the prognostic value of these risk factors.