Current Medicinal Chemistry - Volume 20, Issue 5, 2013

Estrogen receptor (ER) expression is the main indicator of potential responses to endocrine therapy (ET), and approximately 70% of human breast cancers (BCs) are hormone-dependent and ER-positive. The introduction of adjuvant systemic therapy led to a significant improvement in post-surgical survival and a reduction in disease relapse, especially in women with early BC and those with ER+ tumors, who may receive ET alone or in combination with cytotoxic therapy. Adjuvant ET currently consists of (i) ovarian suppression, (ii) selective estrogen receptor modulators (SERMs) and down-regulators, and (iii) aromatase inhibitors (AIs). In patients with ER+ tumors pharmacologic ovary suppression with gonadotropin-releasing hormone agonists in combination with standard adjuvant therapy is generally more effective than adjuvant chemotherapy alone. Tamoxifen is the best established SERM, has favorable effects on BC control and bone metabolism, but also has adverse effects due to its estrogenic activity in other tissues. For these reasons, other SERMs have been developed. Fulvestrant is an ER down-regulator with several potential advantages over SERMs, including a 100-fold increase in its affinity for ER compared with tamoxifen and no estrogen-like activity in the uterus. The inhibition of the aromatase system with third-generation AIs is associated with improved survival in patients with advanced BC compared with SERMs. In postmenopausal patients with ER+ BC adjuvant treatment with AIs should be performed, either as sequential treatment after tamoxifen or as upfront therapy. Studies evaluating the role of AIs as first-line therapy are ongoing and the results are encouraging.

Triple-negative breast cancer (TNBC), that is breast cancer which stains negatively at immunohistochemistry for estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor 2 (HER2), comprises a particularly aggressive subtype of breast cancer, with high rate of early local and distant relapse. TNBC have demonstrated sensitivity to cytotoxic treatment regimens, but in the absence of HER2, ER and PR there is no benefit from hormonal therapy or trastuzumab. The lack of known specific molecular targets has promoted abundant research in order to find possible “vulnerabilities” in TNBC and the evaluation of novel biomarkers overcoming the traditional approach based on hormonal receptors and HER2-targeted therapy is one of the priorities in breast cancer research. Drugs under investigation can be broadly subdivided into four groups: (1) Agents that create DNA damage (i.e. cisplatin, cyclophosphamide); (2) Agents that inhibit poly (ADP-ribose) polymerase (PARP); (3) Tyrosin-kinase inhibitors and monoclonal antibodies; (4) Agents that inhibit downstream signals. Several preclinical and early phase clinical trials for the treatment or management of patients with triple-negative breast tumors are underway. Nonetheless, so far the major issue to deal with when trying to provide evidence for TNBC is the small numbers of the sample in the clinical studies and the retrospective nature of most of them. Future large studies could help in defining optimal treatment strategies for TNBC, both in the advanced setting as well as in the (neo) adjuvant setting.

Sarcomas of the soft tissue are a heterogeneous, rare and complex group of mesenchymal malignant tumors, accounting for less than 1% of all adult malignancies and about 10-15% of childhood cancer. Despite local disease control obtained with surgery and pre- or postoperative radiotherapy, roughly one half of patients with high-grade tumors experience metastatic disease. The adjunction of chemotherapy, either before or after resection, is not currently viewed as standard practice due to the lack of reproducible impact on survival. The 1997 SMAC meta-analysis based on individual data from randomized studies confirmed a significant impact of adjuvant chemotherapy on both local and metastatic relapse, without any significant benefit on survival. Further meta-analyses demonstrated a significant benefit also in overall survival. Yet, the latest adjuvant EORTC trial was disappointedly negative. To date, adjuvant chemotherapy may be recommended as a reasonable option for the high-risk individual patient who should be well informed on the possible risks and benefits of treatment. Also the indications for neoadjuvant chemotherapy remain controversial. A local benefit may be gained, facilitating surgery, but data on survival are limited and affected by a strong patient selection bias. In order to improve our knowledge on sarcomas and to offer patients the best of current standards, we strongly recommend that all patients be referred to a sarcoma multidisciplinary group, under whose supervision they could receive the correct combined-modality management as well as have access to new clinical trials appropriately stratified for risk and histological and/or molecular subtypes.

In the long human tradition honey has been used not only as a nutrient but also as a medicine. Its composition is rather variable and depends on the floral source and on external factors, such as seasonal, environmental conditions and processing. In this review, specific attention is focused on absorption, metabolism, and beneficial biological activities of honey compounds in human. Honey is a supersaturated solution of sugars, mainly composed of fructose (38%) and glucose (31%), containing also minerals, proteins, free amino acids, enzymes, vitamins and polyphenols. Among polyphenols, flavonoids are the most abundant and are closely related to its biological functions. Honey positively affects risk factors for cardiovascular diseases by inhibiting inflammation, improving endothelial function, as well as the plasma lipid profile, and increasing low-density lipoprotein resistance to oxidation. Honey also displays an important antitumoral capacity, where polyphenols again are considered responsible for its complementary and overlapping mechanisms of chemopreventive activity in multistage carcinogenesis, by inhibiting mutagenesis or inducing apoptosis. Moreover, honey positively modulates the glycemic response by reducing blood glucose, serum fructosamine or glycosylated hemoglobin concentrations and exerts antibacterial properties caused by its consistent amount of hydrogen peroxide and non-peroxide factors as flavonoids, methylglyoxal and defensin-1 peptide. In conclusion, the evidence of the biological actions of honey can be ascribed to its polyphenolic contents which, in turn, are usually associated to its antioxidant and anti-inflammatory actions, as well as to its cardiovascular, antiproliferative and antimicrobial benefits.

The development of molecular analyses for thyroid pathologies is on going. These analyses provide new diagnostic tools with the aim of accurately distinguishing malignant and benign thyroid tumors. They are particularly useful as most of them can be done preoperatively on thyroid fine-needle aspiration biopsy samples. Furthermore, molecular biomarkers may play a promising role since they are able to predict the prognosis of patients with thyroid tumors. Moreover, identification of molecular markers as well as a better understanding of thyroid carcinogenesis will help develop innovative targeted therapies, particularly in patients with metastatic iodo-resistant thyroid carcinoma. To date, four types of somatic genetic alterations are known to hold potential interest for the diagnosis and/or prognosis of follicular cell-derived thyroid carcinomas: BRAF and RAS mutations, and RET/PTC and PAX8/PPARγ rearrangements. Other recent molecular biomarkers have been investigated in thyroid oncology, in particular different microRNA signatures. This review describes the different aspects of ancillary methods, including those bassed on molecular biology, that are of current interest for the diagnosis, prognosis and treatment of follicular cell-derived thyroid carcinomas.

Several epidemiological and animal studies have suggested that polyphenols, a group of secondary plant metabolites occurring mainly in the plant kingdom, may have a protective effect against some chronic degenerative diseases such as cancer. Polyphenols are part of the human diet, being present in vegetal food and beverages. Among them, an olive biophenol named hydroxytyrosol [2-(3,4- dihydroxyphenyl)ethanol, HTyr] has recently received particular attention because of its antioxidant, antiproliferative, pro-apoptotic, and anti-inflammatory activities, which have the potential to specifically counteract all cancer hallmarks, thus representing the expectant biological activities underlying the anti-tumor properties of this polyphenol. After a description of the synthetic procedures to prepare pure HTyr, this review takes into consideration the chemopreventive and chemotherapeutic potential of HTyr as the result of its antioxidant, antiproliferative and anti-inflammatory activities. In particular, the review is focused on the current knowledge of the main cellular and molecular mechanisms used by HTyr to affect carcinogenesis, highlighting the specific oncogenic and inflammatory signaling pathways potentially targeted by HTyr.

Protein kinase CK2 (Casein Kinase 2) is an essential, ubiquitous and highly pleiotropic protein kinase, implicated in several human diseases. In the last decade, several inhibitors of CK2, have been discovered and characterized to be ATP-competitive compounds. However, only one of them, CX-4945, has recently completed Phase I clinical trial as potential anticancer drug. In this review, we report all chemical classes of CK2 inhibitors available in literature, focusing our attention on conventional ATP-competitive and on non ATP-competitive inhibitors, which could represent a new frontier in CK2 inhibition and, consequently, a promising field of study in discovering new drug candidates.

DNA topoisomerases comprise an important family of enzymes that catalyse the induction of topological changes (e.g. relaxation/ supercoiling, catenation/decatenation and knotting/unknotting) in the DNA molecule. These enzymes perform their functions by creating transient either single-stranded or double-stranded breaks in the DNA molecule. Due to their ability to modulate the topology of the DNA molecule, DNA topoisomerases play vital roles in replication, transcription, chromosome separation and segregation, and thus represent an important collection of design targets for novel anticancer drugs. The aim of this review is to provide an overview of the development of catalytic inhibitors of the human topoisomerase IIα enzyme - an important member of the DNA topoisomerase family - as potential novel anticancer agents. The group of catalytic topoII inhibitors is classified into four types according to their molecular mechanism of action: inhibitors that bind to the ATP binding site, inhibitors that prevent the ATP hydrolysis step and trap the enzyme in a closed clamp, inhibitors that block the DNA cleavage and inhibitors that prevent the enzyme binding to the DNA. One of the important considerations highlighted throughout this review is the structure-based perspective of inhibitor design, giving the reader a medicinal chemist's perspective on this vibrant and active field of drug design research.

Neural differentiation of embryonic stem cells (ESC) is considered a promising model to perform in vitro testing for neuroactive and neurotoxic compounds. We studied the potential of a dual reporter murine ESC line to identify bioactive and/or toxic compounds. This line expressed firefly luciferase under the control of the neural cell-specific tubulin alpha promoter (TUBA1A), and renilla luciferase under the control of the ubiquitous translation elongation factor 1-alpha-1 (EEF1A1) promoter. During neural differentiation, TUBA1A activity increased, while EEF1A1 activity decreased. We first validated our test system using the known neurotoxin methyl mercury. This compound altered expression of both reporter genes, with ESC-derived neural precursors being affected at markedly lower concentrations than undifferentiated ESCs. Analysis of a library of 1040 bioactive compounds picked up 127 compounds with altered EEF1A1 and/or TUBA1A promoter activity, which were classified in 4 clusters. Cluster 1 (low EEF1A1 and TUBA1A) was the largest cluster, containing many cytostatic drugs, as well as known neurodevelopmental toxicants, psychotropic drugs and endocrine disruptors. Cluster 2 (high EEF1A1, stable TUBA1A) was limited to three sulfonamides. Cluster 3 (high EEF1A1 and TUBA1A) was small, but markedly enriched in neuroactive and neurotoxic compounds. Cluster 4 (stable EEF1A1, high TUBA1A) was heterogeneous, containing endocrine disruptors, neurotoxic and cytostatic drugs. The dual reporter gene assay described here might be a useful addition to in vitro drug testing panels. Our two-dimensional testing strategy provides information on complex response patterns, which could not be achieved by a single marker approach.

Twenty analogues of the anti-HIV-1 integrase (IN) inhibitors dicaffeoylquinic acids (DCQAs) were prepared. Their IC50 values for 3'-end processing and strand transfer against recombinant HIV-1IN were determined in vitro, and their cell toxicities and EC50 against HIV-1 were measured in cells (ex vivo). Acetylated or benzylated and/or with cyclohexylidene group compounds exhibited no inhibition of integration in biochemical assays or viral replication in HIV-infected cells, with the exception of 16 and 36. Removal of these groups, however, correlated with potent inhibition. Compounds 19, 31, and 38, all digalloyls, exhibited the most robust inhibitory performance in biochemical assays as well as in cell culture and less toxicity than other molecules in the current study.