Background/Aim: Triple negative cancer (TNBC) is a subtype of breast cancer that is highly aggressive, with poor prognosis and responds differently to treatments. This study investigated the role of vorinostat and indole-3carbinol (I3C) on regulating critical receptors that are not normally expressed in TNBC. Materials and Methods: Using real-time PCR, immunostaining, and western blots, the reexpression of estrogen receptor α (ER), progesterone receptor (PR) and human epidermal growth factor receptor-2 (HER2) receptors was examined in four different TNBC cell types. Results: ERα was re-expressed in three subtypes using vorinostat and I3C. Re-expression of the PR by vorinostat was also detected. Neither vorinostat nor I3C resulted in re-expression of the HER2 receptor. A significant decrease in growth and sensitivity to tamoxifen was also noted. Conclusion: The results of this study show that vorinostat and I3C modulate the re-expression of critical receptors in certain subtypes of TNBC through several pathways and these effects can be influenced by the molecular profiles of TNBCs.

Summary Current treatments for metastatic breast cancer are not associated with significant survival benefits despite response rates of over 50%. High-dose therapy with autologous bone marrow transplantation (ABMT) has been investigated, particularly in North America, and prolonged survival in up to 25% of women has been reported, but with a significant treatment-related mortality. However, in patients with haematological malignancies undergoing autologous transplantation, haematopoietic reconstruction is significantly quicker and mortality lower than with ABMT, when peripheral blood progenitor cells (PBPCs) are used. In 32 women with metastatic breast cancer, we investigated the feasibility of PBPC mobilisation with high-dose cyclophosphamide and granulocyte colony-stimulating factor (G-CSF) after 12 weeks' infusional induction chemotherapy and the subsequent efficacy of the haematopoietic reconstitution after conditioning with melphalan and either etoposide or thiotepa. PBPC mobilisation was successful in 28/32 (88%) patients, and there was a rapid posttransplantation haematopoietic recovery: median time to neutrophils >0.5 x l091 -1 was 14 days and to platelets >20 x 109 1 was 10 days. There was no procedure-related mortality, and the major morbidity was mucositis (WHO grade 3-4) in 18/32 patients (56%). In a patient group of which the majority had very poor prognostic features, the median survival from start of induction chemotherapy was 15 months. Thus, PBPC mobilisation and support of high-dose chemotherapy is feasible after infusional induction chemotherapy for patients with metastatic breast cancer, although the optimum drug combination has not yet been determined.

A patient's risk of early recurrence after mastectomy for breast cancer has been estimated by using a combination of four prognostic factors. A computer program, designed to calculate the exact probability of recurrence within 2 years of mastectomy, was accurate when tested on 240 patients. A simple scoring system could identify patients at lower and greater risk than any single factor alone.

Triple-negative breast cancer is a highly heterogeneous and aggressive subtype of breast cancer. Epigenetic drugs are continuing to emerge as promising therapies for triple-negative breast cancer (TNBC). These drugs, including the one used in this study, vorinostat, a histone deacetylase inhibitor (HDAC), are capable of multiple actions and are considered multifunctional drugs. Epigenetic mechanisms have been shown to play a role in the etiology of this cancer, through modulation of DNA methylation, histone modification or microRNAs. We have shown in this study that vorinostat and indole-3-carbinol (I3C) modulated the expression of microRNAs 221 and 222 differently in basal-like-2 (BL2), MSL, basal-like1 (BL1) and M subtypes of TNBC cells. Additional studies demonstrated that combination of tamoxifen and vorinostat significantly decreased expression of miRNA 221 in TNBC cell lines. MiRNAs are short noncoding RNAs that regulate the function of target genes post-transcriptionally. In addition, breast cancer microarrays further showed modulation of a number of other miRNAs that play a role in cell proliferation, drug resistance, cell invasion and metastasis. MicroRNAs are epigenetic targets for drug development. Using a global HDAC activity assay, it was also shown that subtypes of TNBC cells respond differently to vorinostat and I3C treatment, depending on their HDAC activity. HCC70, an African American cell line and a BL2 subtype, had the highest HDAC activity and its activity was significantly decreased by vorinostat treatment compared to BT549 (M), HCC 1806 (BL2), MCF7 (ER positive) and a basal nonmalignant cell line, MCF10A. Both vorinostat and I3C show great promise alone and in combination as effective agents in triple-negative breast cancer. Histone deacetylase inhibitors and dietary agents are emerging as therapy for triple-negative breast cancer and are currently in clinical trials. Citation Format: Beverly Lyn-Cook, Fatemeh NouriEmamzaden, Anfernee Hawkins, George Hammons, Beverly Word. Vorinostat and indole-3-carbinol modulate microRNAs and histone deacetylase activity in subtypes of triple-negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5800.

Epigenetic drugs, such as histone deacetylase inhibitors (HDACi), are continuing to emerge as promising therapies for various cancers. These drugs, including FDA-approved vorinostat, are capable of multiple actions and considered to be multifunctional. Histone deacetylases (HDAC) are chromatin-modifying enzymes that are involved in various cellular events, such as tissue differentiation, autophagy, apoptosis, migration, mitosis and angiogenesis. High levels of HDACs have been detected in several cancers. Early studies in our laboratory showed different effects by vorinostat on global HDAC activity in several triple-negative breast cancer (TNBC) subtypes. This study focused on HDAC 7, which has been associated with increases in cancer stem cells and poor prognosis. Cancer stem cells play an important role in cancer resistance to therapy. Histone deacetylase inhibitors are emerging as therapy for triple-negative breast cancer, which is currently an unmet need in women's health due to the lack of targeted therapies. This study investigated the effects of vorinostat on apoptosis and the modulation of HDAC 7 expression in two subtypes of triple-negative breast cancers, MB231(MSL) and HCC70 (BL-2). Using caspase 3/7 assays vorinostat induced apoptosis. Additionally, flow cytometry and immunostaining were conducted to determine vorinostat's effects on expression of two cancer stem cell (CSC) markers, CD44 and CD24. Western blot and real-time PCR showed a significant decrease (10-fold) in the expression of HDAC 7 by vorinostat in HCC70 cells. A modest decrease (3-fold) was also observed in MB231 cells. CD44 expression was deceased by vorinostat in MB231 cells. This study demonstrated that vorinostat exerts its anticancer effects through several mechanisms, such as inducing apoptosis, downregulating HDAC 7 and decreasing cancer stem cells. This therapy could be beneficial for subtypes of TNBC, such as HCC70, an aggressive basal-like 2 cell line from an African American. Citation Format: Fatemeh Nouri Emamzadeh, Anfernee Hawkins, Gustavo Miranda-Carboni, Rhonda Moore, Beverly Word, Beverly Lyn-Cook. Modulation of HDAC activity in subtypes of triple-negative breast cancer: Effects of vorinostat on HDAC 7 expression and cancer stem cells progression [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr C109.