Distinct stratification within TNBC (McCarthy et al., 2012) highlights the need to better understand the biology of TNBCs in order to determine the therapeutic responses and to stratify patients to effective treatments. invasion in breast cancers. Cabergoline Individual epigenetic regulators may be an option to improve chemo-drug delivery in cancers. This review discussed on molecular signatures of various breast cancer subtypes and on-going attempts in understanding underlying molecular mechanisms of epigenetic regulators as well as providing insights on possible ways to utilize epigenetic enzymes/inhibitors with responses to chemotherapeutic drugs to re-program cellular and biological outcome in TNBCs. strong class=”kwd-title” Keywords: Triple Cabergoline negative breast cancers, TNBCs, epigenetic modifiers, FEC, relapse Introduction Cancer is one of the most common fatal diseases worldwide, and numbers have risen each year between 1971-2008 (National Cancer Statistics 2012). The International Agency for Research on Cancer (IARC), a specialized body of World Health Organization (WHO), reported 14.1 million new cancer cases and 8.2 million cancer-related deaths in 2012. According to IARC, the most common cancers worldwide were lung (13.0%), breast (11.9%), and colorectal (9.7%). Five-year survival was assessed in 32.6 million cancer cases in the same year, with highest fatalities reported in lung (19.4%), liver (9.1%) and stomach (8.8%) cancers (International Agency for Research on Cancer 2013). In Malaysia, breast cancer incidence is the highest, accounted for 17.7% among all other cancer cases. Breast cancer ranked top incidence in females, followed by cervix uteri, colorectal, ovarian and cancer of corpus uteri. Highest breast cancer incidence was seen in Malays encompassing 8,225 indicidence followed by Chinese (7,333 incidence) and Indian (1,705 incidence) (Azizah et al., 2016). Breast cancers are heterogenous in the context of gene expression, mutational profiles, gene copy number aberrations and patient outcomes (Koboldt et al., 2012). Distinct gene expression patterns were used to stratify breast cancer subtypes and also revealed potential prediction of response to therapy. Target protein products elevated downstream of these gene expression GIII-SPLA2 profiles provide opportunities for development of novel therapeutics. Clustering analyses suggested a further five intrinsic molecular subtypes of breast cancers; two ER positive (Luminal A and Luminal B) and three ER negative (normal-like, HER2-positive and Cabergoline TNBC/basal-like) (Perou et al., 2000). More recently an ER-negative subtype called claudin-low or triple negative breast cancers (TNBCs) has been identified which is thought to comprise 7-14% of all breast cancers (Herschkowitz et al., 2012). Breast cancer prognosis progressively worsened from ER-positive to ER-negative subtypes (Figure 1) (Eroles et al., 2012). Open in a separate window Figure 1 Molecular Classification of Breast Cancer Based on Gene-Expression Clustering Defined Two Distinct Groups, the ER-Positive and ER-Negative Groups. The ER-positive group is subdivided into Luminal A, B and Normal-like. The ER-negative group is subdivided into HER2-positive, TNBC/basal-like breast cancers (BLBC). Prognosis worsens in the ER-negative group. As the prognosis moving towards aggressiveness in the ER-negative subtypes, especially in the TNBCs, hormonal therapies are impeccably ineffective, thus the mainstay in the treatment regiment in TNBCs is FEC chemotherapy cocktail. Regardless being responsive to FEC, a subset of patients will progress to relapse which subsequently lead to metastasis. Over the years, the understanding of chemoresistance to FEC remains in a rat race. Countless attempts were conducted worldwide to understand the underlying mechanisms of TNBC heterogeneity features. However, these efforts are still premature to elucidate the main driving mechanisms contributing to non-responsiveness to FEC. Prior to the success of molecular classifications of intrinsic subtypes in breast cancers that concur the aggressiveness, recurrence and resistance to therapeutic regiments, it Cabergoline is important to have a greater understanding of the mechanistic biology involved in the development of TNBCs, including epigenetic cascade that drive the heterogeneity of TNBCs and the aggressive features associated with these tumours. This overview provides a glimpse of the importance of utilizing epigenetic inhibiting agents inherent to the disease whether global or specific epigenetic modifiers holds the key in driving chemoresistance in breast cancer, especially in TNBCs by which its re-programming mechanisms that elude current therapies for therapeutic intervention. TNBC Is Highly Associated With Epithelial-To-Mesenchymal-Transition (EMT) EMT is an invasive feature of the TNBC subtype, which leads to cell invasion and distant metastasis. Over the years, EMT has been one of the main areas of interest in studying distant metastasis in cancers. Under normal conditions, epithelial cells are linked together, within an extracellular matrix environment, maintaining tissues stability (Kiesslich et al., 2013). However, in neoplastic or tumour cells, EMT progresses in a multistep process involving loss of polarity of normal epithelial cells.
Categories