Preclinical and Clinical Trials of New Treatment Strategies Targeting Cancer Stem Cells in Subtypes of Breast Cancer.

Breast cancer (BC) can be classified into various histological subtypes, each associated with different prognoses and treatment options, including surgery, radiation, chemotherapy, and endocrine therapy. Despite advances in this area, many patients still face treatment failure, the risk of metastasis, and disease recurrence, which can ultimately lead to death. Mammary tumors, like other solid tumors, contain a population of small cells known as cancer stem-like cells (CSCs) that have high tumorigenic potential and are involved in cancer initiation, progression, metastasis, tumor recurrence, and resistance to therapy. Therefore, designing therapies specifically targeting at CSCs could help to control the growth of this cell population, leading to increased survival rates for BC patients. In this review, we discuss the characteristics of CSCs, their surface biomarkers, and the active signaling pathways associated with the acquisition of stemness in BC. We also cover preclinical and clinical studies that focus on evaluating new therapy systems targeted at CSCs in BC through various combinations of treatments, targeted delivery systems, and potential new drugs that inhibit the properties that allow these cells to survive and proliferate.

In Vivo and in vitro antitumor activity of tomatine in hepatocellular carcinoma.

Background: There is abundant ethnopharmacological evidence the uses of regarding Solanum species as antitumor and anticancer agents. Glycoalkaloids are among the molecules with antiproliferative activity reported in these species. Purpose: To evaluate the anticancer effect of the Solanum glycoalkaloid tomatine in hepatocellular carcinoma (HCC) in vitro (HepG2 cells) and in vivo models. Methods: The resazurin reduction assay was performed to detect the effect of tomatine on cell viability in human HepG2 cell lines. Programmed cell death was investigated by means of cellular apoptosis assays using Annexin V. The expression of cancer related proteins was detected by Western blotting (WB). Reactive oxygen species (ROS) and calcium were determined by 2,7-dichlorodihydrofluorescein diacetate and Fluo-4, respectively. Intrahepatic HepG2 xenograft mouse model was used to elucidate the effect of tomatine on tumor growth in vivo. Results and Discussion: Tomatine reduced HepG2 cell viability and induced the early apoptosis phase of cell death, consistently with caspase-3, -7, Bcl-2 family, and P53 proteins activation. Furthermore, tomatine increased intracellular ROS and cytosolic Ca+2 levels. Moreover, the NSG mouse xenograft model showed that treating mice with tomatine inhibited HepG2 tumor growth. Conclusion: Tomatine inhibits in vitro and in vivo HCC tumorigenesis in part via modulation of p53, Ca+2, and ROS signalling. Thus, the results suggest the potential cancer therapeutic use of tomatine in HCC patients.

Skewed Signaling through the Receptor for Advanced Glycation End-Products Alters the Proinflammatory Profile of Tumor-Associated Macrophages.

Tumors are complex tissues composed of variable amounts of both non-cellular components (matrix proteins) and a multitude of stromal cell types, which are under an active cross-talk with tumor cells. Tumor-associated macrophages (TAMs) are the major leukocyte population among the tumor-infiltrating immune cells. Once they are infiltrated into tumor stroma they undergo a polarized activation, where the M1 and M2 phenotypes represent the two extreme of the polarization heterogeneity spectrum. It is known that TAMs acquire a specific phenotype (M2), oriented toward tumor growth, angiogenesis and immune-suppression. A growing body of evidences supports the presence of tuning mechanisms in order to skew or restraint the inflammatory response of TAMs and thus forces them to function as active tumor-promoting immune cells. The receptor of advanced glycation end-products (RAGE) is a member of the immunoglobulin protein family of cell surface molecules, being activated by several danger signals and thus signaling to promote the production of many pro-inflammatory molecules. Interestingly, this receptor is paradoxically expressed in both M1 and M2 macrophages phenotypes. This review addresses how RAGE signaling has been drifted away in M2 macrophages, and thus taking advantage of the abundance of RAGE ligands at tumor microenvironment, particularly HMGB1, to reinforce the supportive M2 macrophages strategy to support tumor growth.

Lysyl oxidase isoforms in gastric cancer.

Gastric cancer (GC) is the fifth most frequent cancer in the world and shows the highest incidence in Latin America and Asia. An increasing amount of evidence demonstrates that lysyl oxidase isoforms, a group of extracellular matrix crosslinking enzymes, should be considered as potential biomarkers and therapeutic targets in GC. In this review, we focus on the expression levels of lysyl oxidase isoforms, its functions and the clinical implications in GC. Finding novel proteins related to the processing of these extracellular matrix enzymes might be helpful in the design of new therapies, which, in combination with classic pharmacology, could be used to delay the progress of this aggressive cancer and offer a wider temporal window for clinical intervention.

HMGB1 enhances the protumoral activities of M2 macrophages by a RAGE-dependent mechanism.

The monocyte-macrophage lineage shows a high degree of diversity and plasticity. Once they infiltrate tissues, they may acquire two main functional phenotypes, being known as the classically activated type 1 macrophages (M1) and the alternative activated type 2 macrophages (M2). The M1 phenotype can be induced by bacterial products and interferon-γ and exerts a cytotoxic effect on cancer cells. Conversely, the alternatively activated M2 phenotype is induced by Il-4/IL13 and promotes tumor cell growth and vascularization. Although receptor for advanced glycation end-products (RAGE) engagement in M1 macrophages has been reported by several groups to promote inflammation, nothing is known about the functionality of RAGE in M2 macrophages. In the current study, we demonstrate that RAGE is equally expressed in both macrophage phenotypes and that RAGE activation by high-mobility group protein box1 (HMGB1) promotes protumoral activities of M2 macrophages. MKN45 cells co-cultured with M2 macrophages treated with HMGB1 at different times displayed higher invasive abilities. Additionally, conditioned medium from HMGB1-treated M2 macrophages promotes angiogenesis in vitro. RAGE-targeting knockdown abrogates these activities. Overall, the present findings suggest that HMGB1 may contribute, by a RAGE-dependent mechanism, to the protumoral activities of the M2 phenotype.

The emerging role of the receptor for advanced glycation end products on innate immunity.

Cells from innate immune system are activated by the engagement of germ-line encoded pattern-recognition receptors (PRRs) in response to the microbial insult. These receptors are able to recognize either the presence of highly conserved microbial components called pathogen-associated molecular patterns or endogenous danger-associated molecular patterns. These danger signals are recognized by different types of (PRRs), including the receptor for advanced glycation end products. This new PRR share both ligands and intracellular signaling with Toll-like receptors and thus may cooperate with each other as essential partners to strength inflammatory response. This review summarizes recent advances in understanding the promiscuity of this receptor as well as its role in the context of innate immunity by triggering an inflammatory response when innate immune cells detect infection or tissue injury.

The receptor for advanced glycation end-products: a complex signaling scenario for a promiscuous receptor.

Firstly described in 1992, the receptor for advanced glycation end-products has attracted increasing attention due to its diverse ligand repertoire and involvement in several pathophysiological processes associated with inflammation such as in diabetes, cancer, autoimmune diseases and neurodegenerative diseases. This receptor in addition to its binding capacity for advanced glycation end-products also recognizes some molecules classified as both, pathogen- and damage-associated molecular patterns and thus triggering the transcription of genes encoding inflammatory mediators. Some of these ligands are common for both, the receptor of advanced glycation end-products and members of the Toll-like receptor family, generating shared signaling cascades. Furthermore, these receptors may cooperate as essential partners through the recruitment and assembly of homo- and hetero-oligomers in order to strengthen the inflammatory response. The purpose of this review is to highlight the importance of some particular features of this multiligand receptor, its signaling cascade as well as the cross-talk with some members of the Toll-like receptor family.

The immunobiology of the receptor of advanced glycation end-products: trends and challenges.

Pattern-recognition receptors have been highly conserved in evolution. They recognize danger signals including both pathogen- and damage-associated molecular patterns, also known as alarmins. Several signaling pathways leading to an inflammatory reaction as part of an effective defensive response, are thus triggered. RAGE, a receptor initially considered for advanced glycation end-products, is also known to be activated by several danger signals, thus functioning as a pattern-recognition receptor. As a new member of this family, attempts to unraveling its functioning show that RAGE activation not only results in innate immune response but also contributes to promote and shape the acquired immune reaction. As reported for other members of the family, RAGE presents many polymorphic variants and additional studies are needed to elucidate its significance in immune response and disease susceptibility. Here we describe recent advances unraveling RAGE functions, as well as its significance and challenges in immunobiology.

Characterization of a putative grapevine Zn transporter, VvZIP3, suggests its involvement in early reproductive development in Vitis vinifera L.

BACKGROUND: Zinc (Zn) deficiency is one of the most widespread mineral nutritional problems that affect normal development in plants. Because Zn cannot passively diffuse across cell membranes, it must be transported into intracellular compartments for all biological processes where Zn is required. Several members of the Zinc-regulated transporters, Iron-regulated transporter-like Protein (ZIP) gene family have been characterized in plants, and have shown to be involved in metal uptake and transport. This study describes the first putative Zn transporter in grapevine. Unravelling its function may explain an important symptom of Zn deficiency in grapevines, which is the production of clusters with fewer and usually smaller berries than normal. RESULTS: We identified and characterized a putative Zn transporter from berries of Vitis vinifera L., named VvZIP3. Compared to other members of the ZIP family identified in the Vitis vinifera L. genome, VvZIP3 is mainly expressed in reproductive tissue - specifically in developing flowers - which correlates with the high Zn accumulation in these organs. Contrary to this, the low expression of VvZIP3 in parthenocarpic berries shows a relationship with the lower Zn accumulation in this tissue than in normal seeded berries where its expression is induced by Zn. The predicted protein sequence indicates strong similarity with several members of the ZIP family from Arabidopsis thaliana and other species. Moreover, VvZIP3 complemented the growth defect of a yeast Zn-uptake mutant, ZHY3, and is localized in the plasma membrane of plant cells, suggesting that VvZIP3 has the function of a Zn uptake transporter. CONCLUSIONS: Our results suggest that VvZIP3 encodes a putative plasma membrane Zn transporter protein member of the ZIP gene family that might play a role in Zn uptake and distribution during the early reproductive development in Vitis vinifera L., indicating that the availability of this micronutrient may be relevant for reproductive development.

VvBOR1, the grapevine ortholog of AtBOR1, encodes an efflux boron transporter that is differentially expressed throughout reproductive development of Vitis vinifera L.

Boron (B) is an essential micronutrient for normal development of roots, shoots and reproductive tissues in plants. Due to its role in the structure of rhamnogalacturonan II, a polysaccharide required for pollen tube growth, B deficiency has been associated with the occurrence of parthenocarpic seedless grapes in some varieties of Vitis vinifera L. Despite that, it is unclear how B is mobilized and accumulated in reproductive tissues. Here we describe the characterization of an efflux B transporter, VvBOR1, homolog to AtBOR1, which is involved in B xylem loading in Arabidopsis thaliana roots. VvBOR1-green fluorescent protein (GFP) fusion protein expressed in A. thaliana localizes in the proximal plasma membrane domain in root pericycle cells, and VvBOR1 overexpression restores the wild-type phenotype in A. thaliana bor1-3 mutant plants exposed to B deficiency. Complementation of a mutant yeast strain indicates that VvBOR1 corresponds to a B efflux transporter. Transcriptional analyses during grapevine reproductive development show that the VvBOR1 gene is preferentially expressed in flowers at anthesis and a direct correlation between the expression pattern and B content in grapes was established, suggesting the involvement of this transporter in B accumulation in grapevine berries.

Diabetes and cancer: Looking at the multiligand/RAGE axis.

The association between diabetes and hyperglycemia and the associated increased risk of several solid and hematologic malignancies has been the subject of investigation for many years. Although the association is not fully understood, current knowledge clearly indicates that diabetes may influence malignant cell transformation by several mechanisms, including hyperinsulinemia, hyperglycemia and chronic inflammation. In this context, the receptor for advanced glycation end-products (RAGE) has emerged as a focal point in its contribution to malignant transformation and tumor growth. We highlight how RAGE, once activated, as it manifests itself in conditions such as diabetes or hyperglycemia, is able to continuously bring about an inflammatory milieu, thus supporting the contribution of chronic inflammation to the development of malignancies.

Evidence of involvement of the receptor for advanced glycation end-products (RAGE) in the adhesion of Helicobacter pylori to gastric epithelial cells.

The adherence of Helicobacter pylori to gastric epithelial cells is required for prolonged persistence in the stomach and for induction of injury. Here, we first reported a new role of the receptor for advanced glycation end-products (RAGE) on the adherence of H. pylori to gastric epithelial cells, assessed by different methods and binding to immobilized RAGE. RAGE-targeted knock-down in MKN74 cell line markedly reduced not only the adhesion of H. pylori, but also the levels of IL-8 transcripts and protein released in response to infection. These data suggest that RAGE may represent a new factor on the pathogenesis of H. pylori infection.

High prevalence of virulence-associated genotypes in Helicobacter pylori clinical isolates in the Region del Maule, Chile.

The prevalence of Helicobacter pylori infection and the gastric cancer mortality rate in Chile are remarkably high. This study identified some virulence-associated genes in 78 H. pylori clinical isolates from dyspeptic patients from the Region del Maule, which is the region with the higher gastric cancer mortality rate in the country. The cagA, vacA and babA2 genes were detected in 94.9%, 100% and 97.4%, respectively. Two or more EPIYA C motifs were presented in 48.6% of cagA-positive strains, and this was associated with more severe histopathological findings in the gastric mucosa.