The prognostic role of EZH2 expression in rectal cancer patients treated with neoadjuvant chemoradiotherapy

Loss of enhancer of zeste homologue 2 (EZH2) at tumor invasion front is correlated with higher aggressiveness in colorectal cancer cells

PURPOSE

Enhancer of zeste homolog 2 (EZH2) is associated with epigenetic gene silencing and aggressiveness in many tumor types. However, the prognostic impact of high EZH2 expression is controversially discussed for colorectal cancer. For this reason, we immunohistochemically analyzed EZH2 expression in 105 specimens from colon cancer patients separately for tumor center and invasion front.

METHODS

All sections from tissue microarrays were evaluated manually and digitally using Definiens Tissue Studio software (TSS). To mirror-image the EZH2 status at the tumor invasion front, we treated HCT116 colon cancer cells with the EZH2 inhibitor 3-Deazaneplanocin A (DZNep) and studied the growth of in ovo xenografts in the chorioallantoic membrane (CAM) assay.

RESULTS

We showed a significant decrease in EZH2 expression and the repressive H3K27me3 code at the tumor invasion front as supported by the TSS-constructed heatmaps. Loss of EZH2 at tumor invasion front, but not in tumor center was correlated with unfavorable prognosis and more advanced tumor stages. The observed cell cycle arrest in vitro and in vivo was associated with higher tumor aggressiveness. Xenografts formed by DZNep-treated HCT116 cells showed loosely packed tumor masses, infiltrative growth into the CAM, and high vessel density.

CONCLUSION

The differences in EZH2 expression between tumor center and invasion front as well as different scoring and cutoff values can most likely explain controversial literature data concerning the prognostic value of EZH2. Epigenetic therapies using EZH2 inhibitors have to be carefully evaluated for each specific tumor type, since alterations in cell differentiation might lead to unfavorable results.

Pretreatment Tumor Thickness as a Predictor of Pathologic Complete Response to Neoadjuvant Chemoradiation Therapy for Stage II/III Rectal Adenocarcinoma

OBJECTIVES

To evaluate pretreatment tumor thickness in predicting pathologic complete response (pCR) of stage II/III rectal adenocarcinoma to neoadjuvant chemoradiation (chemoradiotherapy [CRT]).

METHODS

We retrospectively analyzed 185 patients who were diagnosed with stage II or III rectal adenocarcinoma from January 2011 to July 2013 and treated with neoadjuvant intensity-modulated radiation therapy (45 Gy in 1.8-Gy fractions to pelvis and 50 Gy in 2-Gy fractions to rectal tumor as an integrated boost) or 3 dimensionally conformal radiation therapy (45 Gy in 1.8-Gy fractions to pelvis followed by an additional 5.4-Gy to rectal tumor) concurrently with two 3-week cycles of chemotherapy (oxaliplatin 130 mg/m on day 1 and capecitabine 825 mg/m, twice per day from day 1 to 14, cycle 2 starts on week 4). One week after CRT, 36% patients received 1 more cycle of the above chemotherapy and 55% received 1 to 2 cycles of FOLFOX6. Tumor response was categorized as pCR and non-pCR. Tumor thickness measured on magnetic resonance imaging was collected. A multivariate logistic regression model was used to evaluate the association of potential predictors and pCR.

RESULTS

Thirty-eight patients (20.5%) reached pCR. Multivariate analysis found the pretreatment tumor thickness to be associated with higher probability of pCR after adjusting for radiation therapy-surgery interval time and pretreatment carcino-embryonic antigen level. The pretreatment carcino-embryonic antigen level was associated with pCR in the univariate analysis but lost the association in the multivatiate model. The pretreatment T or N stage, tumor volume, distance from tumor to anal verge, craniocaudal length of tumor, radiation therapy technique, and patient age and sex were not associated with pCR.

CONCLUSIONS

We concluded that pretreatment tumor thickness is an independent predictor for pCR of stage II/III rectal adenocarcinoma to the neoadjuvant CRT.

Prognostic value of histone marks H3K27me3 and H3K9me3 and modifying enzymes EZH2, SETDB1 and LSD-1 in colorectal cancer

PURPOSE

Studies on the performance of epigenetic-based biomarkers in colorectal cancer (CRC) are scarce and have shown contradictory results. Thus, we sought to examine the prognostic value of histone-modifying enzymes (EZH2, SETDB1 and LSD-1) and histone post-translational marks (H3K27me3 and H3K9me3) in CRC.

METHODS

A retrospective series of 207 CRC patients primarily submitted to surgery in a cancer center was included in this study. Clinicopathological data were retrieved. One representative paraffin block per case was selected for immunohistochemistry, including normal and CRC tissues whenever possible. The percentage of positive nuclear staining (digital image analysis) was used to classify patients into "low" and "high" expression groups for each biomarker. Correlations between immunoexpression levels, clinicopathological features and clinical outcomes [disease-specific (DSS) and disease-free (DFS) survival] were examined. Statistical significance was set at p < 0.05.

RESULTS

CRC tissues showed significantly lower expression of SETDB1 and higher expression of the remainder four biomarkers compared to normal mucosa. High EZH2 expression correlated with disease recurrence/progression, whereas low LSD1 expression and high H3K9me3 and H3K27me3 expression were associated with more advanced stage. In multivariable analysis, cases with high LSD1 expression displayed significantly better DSS and DFS (HR 0.477, 95% confidence interval: 0.247-0.923) adjusted for pathological TNM stage.

CONCLUSION

EZH2, SETDB1, LSD1, H3K9me3 and H3K27me3 expression are altered in CRC and may play a role in colorectal carcinogenesis. LSD1 immunoexpression levels independently predicted patient outcome in this cohort. Further investigations, using larger series, are warranted to confirm its potential clinical value and unravel underlying molecular mechanisms.

The relationship between EZH2 expression and microRNA-31 in colorectal cancer and the role in evolution of the serrated pathway

Polycomb group protein enhancer of zeste homolog 2 (EZH2) is a methyltransferase that correlates with the regulation of invasion and metastasis and is overexpressed in human cancers such as colorectal cancer. MicroRNA-31 (miR-31) plays an oncogenic role and is associated with BRAF mutation and poor prognosis in colorectal cancer. EZH2 is functionally considered to suppress miR-31 expression in human cancers; however, no study has reported its relationship with colon cancer. We therefore evaluated EZH2 expression using immunohistochemistry and assessed miR-31 and epigenetic alterations using 301 colorectal carcinomas and 207 premalignant lesions. Functional analysis was performed to identify the association between EZH2 and miR-31 using cancer cell lines. In the current study, negative, weak, moderate, and strong EZH2 expressions were observed in 15%, 19%, 25%, and 41% of colorectal cancers, respectively. EZH2 was inversely associated with miR-31 (P < 0.0001), independent of clinicopathological and molecular features. In a multivariate stage-stratified analysis, high EZH2 expression was related to favorable prognosis (P = 0.0022). Regarding premalignant lesions, negative EZH2 expression was frequently detected in sessile serrated adenomas/polyps (SSA/Ps) (76%; P < 0.0001) compared with hyperplastic polyps, traditional serrated adenomas, and non-serrated adenomas (25–36%). Functional analysis demonstrated that the knockdown of EZH2 increased miR-31 expression. In conclusion, an inverse association was identified between EZH2 and miR-31 in colorectal cancers. Our data also showed that upregulation of EZH2 expression may be rare in SSA/Ps. These results suggest that EZH2 suppresses miR-31 in colorectal cancer and may correlate with differentiation and evolution of serrated pathway.

Prognostic value of high EZH2 expression in patients with different types of cancer: a systematic review with meta-analysis

Enhancer of zeste homologue 2 (EZH2) is a potential independent mechanism for epigenetic silencing of tumor suppressor genes in cancer. We conducted an electronic search on PubMed, EMBASE, Web of Science, and Cochrane library to perform this up-to-date meta-analysis. Fifty-one studies with a total of 9444 patients were included. The prevalence of high EZH2 expression was 0.54 (95% CI: 0.47-0.61). High EZH2 expression was significantly associated with poorer prognosis [overall survival: HR 1.54 (95% CI: 1.30-1.78), P < 0.000; disease free survival: HR 1.35 (95% CI: 1.00-1.71), P < 0.000]. In breast cancer, high EZH2 expression correlated with histological types [OR: 1.53 (95CI: 1.13-2.06); P < 0.006], histological grade [OR: 1.62 (95CI: 1.35-1.95); P < 0.000], estrogen receptor (ER) negativity [OR: 2.05 (95CI: 1.67-2.52); P < 0.000], progesterone receptor (PgR) negativity [OR: 1.42 (95CI: 1.03-1.96); P = 0.034], HER-2 positivity [OR: 1.35 (95CI: 1.08-1.69); P = 0.009], and high p53 expression [OR: 1.66 (95CI: 1.07-2.59); P = 0.024]. These results suggest that high EZH2 expression may be a promising prognostic factor to different cancers. High EZH2 expression tends to correlate with pathological types, histological grade, ER negativity, PgR negativity, HER-2 positivity and p53 high expression in breast cancer.

EZH2 is overexpressed in laryngeal squamous cell carcinoma and enhances the stem-like properties of AMC-HN-8 cells

The enhancer of zeste 2 polycomb repressive complex 2 subunit (EZH2) histone methyltransferase is the catalytic subunit of polycomb repressive complex 2 (PRC2), which is important for epigenetic regulation. EZH2 is highly expressed in various types of tumors, and its high-level expression promotes the progression and invasion of certain tumors. However, the expression level of EZH2 and its functions in laryngeal squamous cell carcinomas are unknown. In the present study, the level of EZH2 expression in laryngeal squamous cell carcinomas was evaluated using immunochemical staining and reverse transcription-quantitative polymerase chain reaction. EZH2 was overexpressed in AMC-HN-8 cells with lentiviral transfection. Cell proliferation, apoptosis, cell-cycle, chemotherapy-sensitivity and in vivo tumorigenic assays were performed. The results indicated that EZH2 was highly expressed in laryngeal squamous cell carcinomas. Additionally, EZH2 overexpression promoted proliferation, accelerated cell-cycle progression and enhanced the tumorigenicity in laryngeal squamous cancer cells. More importantly, EZH2 enhanced the chemotherapy resistance of these cells. Overall, the results indicated that EZH2 promotes the progression of laryngeal squamous cell cancer and could be a potential chemotherapeutic target for the treatment of such cancer.

EZH2 Expression and its Correlation with Clinicopathological Features in Patients with Colorectal Carcinoma

Objective

To explore the correlation between the enhancer of zeste homolog 2 (EZH2) expression and clinicopathological features in colorectal cancer patients.

Methods

A total of sixty-six patients with colorectal carcinoma were admitted to our general surgery department from January 2011 to December 2014. The EZH2 expression levels in the cancer tissues (CTs) from the 66 patients with colorectal cancer and those in distant normal colorectal tissues from 30 cases were examined through immunohistochemistry and western blotting assays. The relationship between the expression of EZH2 and the clinicopathological features and prognosis of the patients was analyzed.

Results

EZH2 in colorectal carcinoma tissues is granularly brown, predominantly expressed and diffused in the nuclei of tumor cells. Positive rates of EZH2 in intestinal CTs and in distant normal intestinal tissues are 62.12% (41/66) and 6.67% (2/30), respectively with significant difference (P < 0.05). Western blotting also confirmed its elevated expression in colorectal CTs. EZH2-positive expression in CTs was related to degree of differentiation, Duke staging, and tumor size (P < 0.05) but was unrelated to the patient’s gender, age or tumor site (P = 0.05). The 3-year progression-free survival (PFS) rates of the EZH2-positive group and the EZH2-negative group were 43.8% and 67.5%, respectively. The risk of disease progression of the EZH2-positive patients in the follow-up period was significantly higher than that of the EZH2-negative patients (HR = 2.49, 95% CI = 1.04–4.80, P < 0.05).

Conclusion

EZH2 is closely related to colorectal carcinoma development and disease progression, and thus could be used as a tumor biomarker that may indicate prognosis.