AlphaB-crystallin and breast cancer: role and possible therapeutic strategies

AlphaB-crystallin (HSPB5) is one of the most prominent and well-studied members of the small heat shock protein (sHsp) family. To date, it is known that this protein modulates significant cellular processes and therefore, it is not surprising that its deregulation is involved in various human pathologies, including cancer diseases. Despite the pathogenic significance of HSPB5 in cancer and its regulatory mechanism related to aggressiveness is poorly understood, several reports describe the association of breast carcinoma progression with HSPB5, whose expression is also considered an independent predictor of breast cancer metastasis to the brain. Indeed, numerous authors indicate HSPB5 as a new valuable biomarker for clinicopathological parameters and poor prognosis in breast cancer. Considering the cytoprotective, anti-apoptotic, pro-angiogenic, and pro-metastatic properties of the sHsps, it is not surprising that they are considered as promising targets for anticancer treatment, even though, at present, a deeper understanding of their mode of action is needed to allow the development of precise therapeutic interventions. Data on the direct inhibition of different sHsps demonstrate promising results in cancer pathologies; however, specific strategies against HSPB5 have not been considered. This review highlights the most relevant findings on HSPB5 and its role in breast cancer, as well as the possible strategies in using HSPB5 inhibition for therapeutic purposes.     

Oncogenic role and therapeutic target of leptin signaling in breast cancer and cancer stem cells

Significant correlations between obesity and incidence of various cancers have been reported. Obesity, considered a mild inflammatory process, is characterized by a high level of secretion of several cytokines from adipose tissue. These molecules have disparate effects, which could be relevant to cancer development. Among the inflammatory molecules, leptin, mainly produced by adipose tissue and overexpressed with its receptor (Ob-R) in cancer cells is the most studied adipokine. Mutations of leptin or Ob-R genes associated with obesity or cancer are rarely found. However, leptin is an anti-apoptotic molecule in many cell types, and its central roles in obesity-related cancers are based on its pro-angiogenic, pro-inflammatory and mitogenic actions. Notably, these leptin actions are commonly reinforced through entangled crosstalk with multiple oncogenes, cytokines and growth factors. Leptin-induced signals comprise several pathways commonly triggered by many cytokines (i.e., canonical: JAK2/STAT; MAPK/ERK1/2 and PI-3K/AKT1 and, non-canonical signaling pathways: PKC, JNK and p38 MAP kinase). Each of these leptin-induced signals is essential to its biological effects on food intake, energy balance, adiposity, immune and endocrine systems, as well as oncogenesis. This review is mainly focused on the current knowledge of the oncogenic role of leptin in breast cancer. Additionally, leptin pro-angiogenic molecular mechanisms and its potential role in breast cancer stem cells will be reviewed. Strict biunivocal binding-affinity and activation of leptin/Ob-R complex makes it a unique molecular target for prevention and treatment of breast cancer, particularly in obesity contexts.     

The role of DDX46 in breast cancer proliferation and invasiveness: A potential therapeutic target

DDX46, a member of DEAD-box (DDX) proteins, is associated with various cancers, while its involvement in the pathogenesis of breast cancer hasn't been reported so far. The study demonstrated the overexpression of DDX46 in human breast cancer cells and tissue samples, and correlated with high histological grade and lymph node metastasis. Downregulation of DDX46 in the breast cancer cell lines inhibited their proliferation and invasiveness in vitro. Furthermore, the growth of MDA-MB-231 xenografts was suppressed in nude mice by DDX46 knockingdown. Taken together, our findings suggest that DDX46 is an oncogenic factor in human breast cancer, and a potential therapeutic target.     

The role of miRNAs as a predictor of multicentricity in breast cancer

Expression profiles of miRNAs are shown to be different in various cancers to regulate expression of mRNA or to have a role in inhibition of translation, thus it shows the possible effect in progression, invasion and metastasis of breast cancer cells. The effect of breast conserving treatment in local recurrence and survival rates for the patients who have multicentric breast cancer is still controversial. In our study, we intended to evaluate the foresight of 84 miRNAs which are identified in breast cancer for having differentiated expressions. Thirty-one patients with unifocal and 26 patients with multicentric breast cancer were included in this study. These tissue samples of both malignant and normal breast tissues were kept in RNA later solution at ??80 °C. Eighty-four miRNAs were studied with miScript miRNA PCR Array Human Breast Cancer kit. Fold change, cut off value was accepted as four. In unifocal group, there were 13 upregulated and five downregulated miRNAs and in multicentric group, there were three upregulated and seven downregulated miRNAs. To reach better results for breast cancer diagnosis and treatment, it is important to enlighten tumor biology, and pay attention to target and individual therapy. Thus, miRNAs have potential role in identifying tumor characteristics in supporting diagnosis and resulting with better evaluated disease for better treatment results with individual strategies.

     

A non-replicating oncolytic vector as a novel therapeutic tool against cancer

Cancers are still difficult targets despite recent advances in cancer therapy. Due to the heterogeneity of cancer, a single-treatment modality is insufficient for the complete elimination of cancer cells. Therapeutic strategies from various aspects are needed. Gene therapy has been expected to bring a breakthrough to cancer therapy, but it has not yet been successful. Gene therapy also should be combined with other treatments to enhance multiple therapeutic pathways. In this view, gene delivery vector itself should be equipped with intrinsic anti-cancer activities. HVJ (hemagglutinating virus of Japan; Sendai virus) envelope vector (HVJ-E) was developed to deliver therapeutic molecules. HVJ-E itself possessed anti-tumor activities such as the generation of anti-tumor immunities and the induction of cancer-selective apoptosis. In addition to the intrinsic anti-tumor activities, therapeutic molecules incorporated into HVJ-E enabled to achieve multi-modal therapeutic strategies in cancer treatment. Tumor-targeting HVJ-E was also developed. Thus, HVJ-E will be a novel promising tool for cancer treatment.     

The role of Herceptin in early breast cancer

Herceptin is widely regarded as the most important development in the treatment of breast cancer since Tamoxifen and the development of the multidisciplinary team (MDT). It is particularly exciting from an oncological polint of view as it represents success in the emerging field of specific targeted therapies to specific molecular abnormalities in tumour cells. This review will focus on the nature of the Her2 overexpression and the role of herceptin in the treatment of early breast cancer.     

AGTR1 as a therapeutic target in ER-positive and ERBB-negative breast cancer cases

Comment on: Rhodes DR, et al. Proc Natl Acad Sci USA 2009; 106:10284-9.     

The potential benefits of low-molecular-weight heparins in cancer patients

Prostate cancer remains a significant public health problem, with limited therapeutic options in the setting of castrate-resistant metastatic disease. Angiogenesis inhibition is a relatively novel antineoplastic approach, which targets the reliance of tumor growth on the formation of new blood vessels. This strategy has been used successfully in other solid tumor types, with the FDA approval of anti-angiogenic agents in breast, lung, colon, brain, and kidney cancer. The application of anti-angiogenic therapy to prostate cancer is reviewed in this article, with attention to efficacy and toxicity results from several classes of anti-angiogenic agents. Ultimately, the fate of anti-angiogenic agents in prostate cancer rests on the eagerly anticipated results of several key phase III studies.     

Apoptosis as a therapeutic tool in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory synovitis that is dominated by the presence of macrophages, lymphocytes and synovial fibroblasts, which leads to the destruction of bone and cartilage. The effectiveness of therapies that are directed against tumour-necrosis factor and interleukin-1 has identified macrophages as a crucial target for therapeutic intervention. However, not all patients respond to these therapies, and the benefits of this form of treatment are short lived. Recent work indicates that the insufficient apoptosis of inflammatory cells in the RA joint might contribute to pathogenesis. In this article, I characterize the mechanisms that prevent the apoptosis of chronic inflammatory cells in the RA joint, to identify potential new targets for the treatment of RA.     

The role of endocrine therapy in primary breast cancer

A recent overview of the results of all trials of adjuvant chemotherapy suggests a clinically and statistically significant advantage for premenopausal women with positive axillary nodes. The results of the same approach for all other women with early breast cancer are very disappointing. These data suggest that contrary to the original hypothetical model, adjuvant chemotherapy is exerting its effect indirectly via chemical castration. In contrast, the results of trials of adjuvant tamoxifen have been more promising and, again, in contrast to the original premises, it would appear that a modest improvement in survival and delay in recurrence can be achieved amongst all groups of women independent of age, nodal status and oestrogen receptor content of the primary tumour. In order to explain these counter-intuitive observations, it is necessary to elaborate an alternative biological model. This paper describes the current thinking on the mode of action of the "anti-oestrogens" and the possible role of inhibitory growth factors activated indirectly by anti-oestrogens. Future trials of adjuvant systemic therapy for early breast cancer should include studies on the duration of tamoxifen, comparing 2 yr with longer, and a comparison of tamoxifen alone with polychemotherapy for premenopausal node positive patients.     

Promising therapeutic options in triple-negative breast cancer

Triple-negative breast cancer (TNBC) has a greater risk of recurrence despite more aggressive therapy even in lowrisk category. TNBC is high grade, hormone receptor and HER-2 negative, it exhibits a high level of Ki-67 staining and expresses the epithelial growth factor receptor (EGFR). Because of its expression profile, treatment options are limited to cytotoxic chemotherapy. Molecular defects that give rise to BRCA1-associated breast cancer also occur in TNBC. Thus, the combination of poly-(ADP-ribose)-polymerase (PARP) inhibitors with drugs that cause DNA breakages, such as alkylating agents and topoisomerase I inhibitors, could theoretically potentiate the efficacy of each drug in patients with TNBC. Clinical trials with various targeted approaches alone or in combination with different chemotherapeutic agents are currently underway. In this review, current and future treatment approaches in TNBC with novel targeted agents are discussed.     

RET in breast cancer: functional and therapeutic implications

Recent studies demonstrate that the receptor tyrosine kinase RET is overexpressed in a subset of ER-positive breast cancers and that crosstalk between RET and ER is important in responses to endocrine therapy. The development of small molecular inhibitors that target RET allows the opportunity to consider combination therapies as a strategy to improve response to treatment and to prevent and combat endocrine resistance. This review discusses: (i) the current knowledge about RET, its co-receptors and ligands in breast cancer; (ii) the breast cancer clinical trials involving agents that target RET; and (iii) the challenges that remain in terms of specificity of available inhibitors and in understanding the complex molecular mechanisms that underlie the resistance to endocrine therapy.     

Novel racemosin B derivatives as new therapeutic agents for aggressive breast cancer

Carbazole derivatives show anti-cancer activity and are of great interest for drug development. In this study, we synthesized and analyzed several new alkylamide derivatives of racemocin B, a natural indolo[3,2-a]carbazole molecule originally isolated from the green alga Caulerpa racemose. Several alkylamide derivatives were found to exhibit moderate to strong growth inhibition against human breast cancer cell lines. They induced G2/M cell cycle arrest and apoptosis in the aggressive triple-negative breast cancer cell line MDA-MB-231. Among these derivatives, compound 25 with the lowest IC₅₀ induced cell death by suppressing autophagy. This was accompanied by inhibition of autophagic flux and accumulation of autophagy protein 1 light chain 3, LC3II, and p62. The novel alkylamide derivative offers a potential new treatment for human breast cancer.     

The role of estrogen in the initiation of breast cancer

Estrogens are considered to play a major role in promoting the proliferation of both the normal and the neoplastic breast epithelium. Their role as breast carcinogens has long been suspected and recently confirmed by epidemiological studies. Three major mechanisms are postulated to be involved in their carcinogenic effects: stimulation of cellular proliferation through their receptor-mediated hormonal activity, direct genotoxic effects by increasing mutation rates through a cytochrome P450-mediated metabolic activation, and induction of aneuploidy. Recently it has been fully demonstrated that estrogens are carcinogenic in the human breast by testing in an experimental system the natural estrogen 17β-estradiol (E₂) by itself or its metabolites 2-hydroxy, 4-hydroxy, and 16-a-hydroxy-estradiol (2-OH-E₂, 4-OH-E₂, and 16--OH E₂), respectively, by inducing neoplastic transformation of human breast epithelial cells (HBEC) MCF-10F in vitro to a degree at least similar to that induced by the chemical carcinogen benz(a)pyrene (BP). Neither Tamoxyfen (TAM) nor ICI-182,780 abrogated the transforming efficiency of estrogen or its metabolites. The E₂ induced expression of anchorage independent growth, loss of ductulogenesis in collagen, invasiveness in Matrigel, is associated with the loss of 9p11-13 and only invasive cells that exhibited a 4p15.3-16 deletion were tumorigenic. Tumors were poorly differentiated ER- and progesterone receptor negative adenocarcinomas that expressed keratins, EMA and E-cadherin. The E₂ induced tumors and tumor-derived cell lines exhibited loss of chromosome 4, deletions in chromosomes 3p12.3-13, 8p11.1-21, 9p21-qter, and 18q, and gains in 1p, and 5q15-qter. The induction of complete transformation of the human breast epithelial cell MCF-10F in vitro confirms the carcinogenicity of E₂, supporting the concept that this hormone could act as an initiator of breast cancer in women. This model provides a unique system for understanding the genomic changes that intervene for leading normal cells to tumorigenesis and for testing the functional role of specific genomic events taking place during neoplastic transformation.