Effects of enhancer of zeste homolog 2 and mucin 1 expressions on treatment response in breast cancer

OBJECTIVE

Breast cancer is the most common malignancy in women. In the treatment of these patients, pathological complete response is defined as the absence of invasive cancer in breast or lymph node tissue after the completion of neoadjuvant chemotherapy. In this study, we aimed to investigate the relationship of enhancer of zeste homolog 2 and mucin 1 expressions with pathological complete response in patients with breast cancer receiving neoadjuvant chemotherapy.

METHODS

A total of 151 patients were included in the study. Enhancer of zeste homolog 2 and mucin 1 expressions were evaluated in the biopsy materials pre-neoadjuvant chemotherapy and post-neoadjuvant chemotherapy surgical material, and their relationship with pathological complete response was investigated.

RESULTS

The pathological complete response rates were significantly higher among the hormone receptor-negative patients, those with a high Ki-67 score, and patients with HER2-positive. Higher pathological complete response rates were obtained from patients with enhancer of zeste homolog 2 expression positivity pre-neoadjuvant chemotherapy. In addition, after neoadjuvant chemotherapy, enhancer of zeste homolog 2 expression was found to be completely negative in materials with pathological complete response; that is, in breast tissues considered to be tumor-free. While there was no significant relationship between mucin 1 expression and pathological complete response pre-neoadjuvant chemotherapy, mucin 1 expression was determined to significantly differ between the tissues with and without pathological complete response among the surgical materials examined.

CONCLUSION

In our study investigating the relationship between enhancer of zeste homolog 2 and mucin 1 expression and pathological complete response in patients who received neoadjuvant chemotherapy, we found that enhancer of zeste homolog 2 expression could be used as a predictive marker for pathological complete response. However, mucin 1 expression was not associated with pathological complete response.

Humanized NOD/SCID/IL2rγnull mice exhibit functionally augmented human regulatory T cells associated with enzymatic up-regulation of H3K27me3 in comparison with humans

Humanized non-obese diabetic/severe combined immunodeficiency/interleukin-2 receptor-γ-null (NOD/SCID/IL2rγ^null ) [humanized (huNSG)] mice engrafted with human hematopoietic cells have been used for investigations of the human immune system. However, the epigenetic features of the human regulatory T (T_reg ) cells of huNSG mice have not been studied. The objective of this study was to clarify the characteristics of human T_reg cells in huNSG mice, especially in terms of the epigenetic aspects. We compared the populations, inhibitory molecule expression and suppressive capacity of human T_reg cells in spleens harvested from the huNSG mice 120 days after the engraftment of human umbilical cord blood CD34⁺ cells with human peripheral blood mononuclear cells (PBMCs). Histone modifications and enhancer of zeste homolog 2 (Ezh2), an H3K27 methyltransferase, of human T_reg cells were quantified in huNSG mice and human PBMCs. The effect of Ezh2 inhibitor on human T_reg cells exposed to interleukin (IL)-6 was also compared between them. Human T_reg cells in the spleens of huNSG mice showed an increased proportion among CD4⁺ T cells, higher expressions of forkhead box protein 3 (FoxP3), cytotoxic T lymphocyte antigen 4 (CTLA-4) and glucocorticoid-induced tumor necrosis factor-related protein (GITR), a higher production of IL-10 and enhanced suppressive capacity when compared with those in human PBMCs. H3K27me3 and Ezh2 were specifically up-regulated in human T_reg cells of huNSG mice in comparison with those of human PBMCs. The decrease in T_reg cells induced by IL-6 exposure was attenuated in huNSG mice when compared with human PBMCs, while the difference between them was cancelled by addition of Ezh2 inhibitor. In conclusion, huNSG mice exhibit functionally augmented human T_reg cells owing to enzymatic up-regulation of H3K27me3.

Association of clinicopathologic characteristics and outcomes with EZH2 expression in patients with breast cancer in East Azerbaijan, Iran

Background

Recently, it was found that the overexpression and mutation status of EZH2 affect cancer progression and patient outcome in several human tumors. We aimed to evaluate the clinicopathologic significance of EZH2 in patients with breast cancer.

Methods

This was an analytical descriptive study of surgical specimens of primary breast tumors. Specimens were analyzed immunohistochemically for EZH2, estrogen receptor, progesterone receptor, Ki-67, P53, and human epidermal growth factor receptor 2 (HER2) expressions. Regression analysis was performed to calculate hazard ratios (HRs) and 95% CIs. Kaplan–Meier and Cox regression models were used to estimate the overall survival (OS) and disease-free survival (DFS).

Results

We included 100 patients with breast cancer (mean age 51.05±9.54 years). The multivariate regression analysis showed that HER2-positive patients had approximately twice the levels of EZH2 expression compared with HER2-negative patients (HR 2.16, 95% CI 0.48–11.49). The likelihood of EZH2 expression was significantly higher in patients with lymph node involvement than in those without (HR 8.44, 95% CI 3.06–23.33; P≤0.05). EZH2 expression did not have any significant effect on the OS, although the mean OS in high EZH2 expression was shorter than for those with low EZH2 expression (655 vs 787 days; log-rank P=0.336). The mean DFS was 487 days for patients with high EZH2 expression compared with 908 days for those with low EZH2 expression (log-rank P=0.188).

Conclusion

There was no association found between EZH2 expression and OS and DFS in our patients. Further studies involving larger sample sizes, and conducted in different populations, are needed to validate this hypothesis.