Search

Despite substantial progress in cancer therapy, colorectal cancer (CRC) is still the third leading cause of cancer death worldwide, mainly due to the acquisition of resistance and disease recurrence in patients. Growing evidence indicates that deregulation of hormone signaling pathways and their cross-talk with other signaling cascades inside CRC cells may have an impact on therapy resistance. MicroRNAs (miRNAs) are small conserved non-coding RNAs thatfunction as negative regulators in many gene expression processes. Key studies have identified miRNA alterations in cancer progression and drug resistance. In this review, we provide a comprehensive overview and assessment of miRNAs role in hormone signaling pathways in CRC drug resistance and their potential as future targets for overcoming resistance to treatment.

Extracellular vesicles (EVs) are sophisticated and sensitive messengers released by cells to communicate with and influence distant and neighboring cells via selective transfer of bioactive content, including protein lipids and nucleic acids. EVs have therefore attracted broad interest as new and refined potential therapeutic systems in many diseases, including cancer, due to their low immunogenicity, non-toxicity, and elevated bioavailability. They might serve as safe and effective vehicles for the transport of therapeutic molecules to specific tissues and cells. In this review, we focus on EVs as a vehicle for gene therapy in cancer. We describe recent developments in EV engineering to achieve efficient intracellular delivery of cancer therapeutics and avoid off-target effects, to provide an overview of the potential applications of EV-mediated gene therapy and the most promising biomedical advances.

The involvement of sirtuins (SIRTs) in modulating metabolic and stress response pathways is attracting growing scientific interest. Some SIRT family members are located in mitochondria, dynamic organelles that perform several crucial functions essential for eukaryotic life. Mitochondrial dysfunction has emerged as having a key role in a number of human diseases, including cancer. Here, we investigated mitochondrial damage resulting from treatment with a recently characterized pan-SIRT inhibitor, MC2494. MC2494 was able to block mitochondrial biogenesis and function in terms of ATP synthesis and energy metabolism, suggesting that it might orchestrate cell response to metabolic stress and thereby interfere with cancer promotion and progression. Targeting mitochondrial function could thus be considered a potential anticancer strategy for use in clinical therapy.

Histone deacetylase 2 (HDAC2) is overexpressed or mutated in several disorders such as hematological cancers, and plays a critical role in transcriptional regulation, cell cycle progression and developmental processes. Here, we performed comparative transcriptome analyses in acute myeloid leukemia to investigate the biological implications of HDAC2 silencing versus its enzymatic inhibition using epigenetic-based drug(s). By gene expression analysis of HDAC2-silenced vs wild-type cells, we found that HDAC2 has a specific role in leukemogenesis. Gene expression profiling of U937 cell line with or without treatment of the well-known HDAC inhibitor vorinostat (SAHA) identifies and characterizes several gene clusters where inhibition of HDAC2 ‘mimics’ its silencing, as well as those where HDAC2 is selectively and exclusively regulated by HDAC2 protein expression levels. These findings may represent an important tool for better understanding the mechanisms underpinning immune regulation, particularly in the study of major histocompatibility complex class II genes.

Histone deacetylase inhibitors (HDACis) have received considerable attention for their anti-tumoral properties. We report here the effects of two HDACis, SAHA and MS-275, on the biology of mesenchymal stem cells (MSCs). It is well known that HDACis trigger both DNA damage responses and actual DNA damage in cancer cells. On this premise, we evaluated HDACis influence on DNA damage pathways in MSCs. We analyzed a panel of genes involved in the regulation of base and nucleotide excision repair, mismatch repair, and double strand break repair. That a majority of the analyzed genes displayed significant expression changes upon incubation with SAHA or MS-275 suggested that regulation of their expression is greatly affected by HDACis. The complex expression pattern, with some genes up-regulated and other under-expressed, did not allow to foresee whether these changes allow cells cope with stressful DNA damaging stimuli. Furthermore, we evaluated the biological outcome following treatment of MSCs with DNA damaging agents (H(2)O(2) and UV) in presence of HDACis. In these settings, MSCs treated with H(2)O(2) or UV radiation underwent apoptosis and/or senescence, and pre-incubation with HDACi exacerbated cell death phenomena. Accordingly, the number of cells harboring 8-oxo-7,8-dihydroguanine (8oxodG), a hallmark of DNA oxidative damage, was significantly higher in samples incubated with HDACis compared to controls. In summary, our findings suggest that SAHA and MS-275, even at low effective doses, can alter the biology of MSCs, diminishing their ability to survive the effects of DNA-damaging agents.

Altered expression and activity of histone deacetylases (HDACs) have been correlated with tumorigenesis. Inhibitors of HDACs (HDACi) induce acetylation of histone and non-histone proteins affecting gene expression, cell cycle progression, cell migration, terminal differentiation and cell death. Here, we analyzed the regulation of ARHGEF3, a RhoA-specific guanine nucleotide exchange factor, by the HDACi MS275 (entinostat). MS275 is a well-known benzamide-based HDACi, which induces differentiation of the monoblastic-like human histiocytic lymphoma cell line U937 to monocytes/macrophages. Incubation of U937 cells with MS275 resulted in an up regulation of ARHGEF3, followed by a significant enhancement of the marker of macrophage differentiation CD68. ARHGEF3 protein is primarily nuclear, but MS275 treatment rapidly induced its translocation into the cytoplasm. ARHGEF3 cytoplasmic localization is associated with activation of the RhoA/Rho-associated Kinase (ROCK) pathway. In addition to cytoskeletal rearrangements orchestrated by RhoA, we showed that ARHGEF3/RhoA-dependent signals involve activation of SAPK/JNK and then Elk1 transcription factor. Importantly, MS275-induced CD68 expression was blocked by exposure of U937 cells to exoenzyme C3 transferase and Y27632, inhibitors of Rho and ROCK respectively. Moreover, ARHGEF3 silencing prevented RhoA activation leading to a reduction in SAPK/JNK phosphorylation, Elk1 activation and CD68 expression, suggesting a crucial role for ARHGEF3 in myeloid differentiation. Taken together, our results demonstrate that ARHGEF3 modulates acute myeloid leukemia differentiation through activation of RhoA and pathways directly controlled by small GTPase family proteins. The finding that GEF protein modulation by HDAC inhibition impacts on cell differentiation may be important for understanding the antitumor mechanism(s) by which HDACi treatment stimulates differentiation in cancer.

The known DNMT inhibitor SGI-1027 4 has been synthesized using as key steps Pd-catalyzed Ar-N bond formation reactions performed in a sequential or convergent manner. In the former approach, a by-product, which corresponds to the incorporation of two units of 4-chloroquinoline, was also isolated. The biological effects of compound 4 in the U937 human leukemia cell line are also described.

A series of 7,12-dihydroindolo[3,2-d][1]benzazepine-6(5H)-ones (paullones) substituted at C9/C10 (Br) and C2 (Me, CF(3), CO(2)Me) have been synthesized by a one-pot Suzuki-Miyaura cross-coupling of an o-aminoarylboronic acid and methyl 2-iodoindoleacetate followed by intramolecular amide formation. Other approaches to the paullone scaffold based on Pd-catalyzed C-H activation were unsuccessful. In vitro enzymatic assay with recombinant human SIRT-1 indicated a strong inhibitory profile for the series, in particular the analogue with a methoxycarbonyl group at C2 and a bromine at C9. These compounds are, in general, inducers of granulocyte differentiation of the U937 acute leukemia cell line and cause a marked increase in pre-G1 of the cell cycle.

MicroRNAs (miRNAs) are small non-coding RNAs 18-25 nucleotides (nt) long able to fine-tune post-transcriptional gene expression. Extensive investigation into biogenesis, mechanism of action and functions of miRNAs has clearly revealed their prompt control in developmental timing, differentiation, proliferation, cell death, and metabolism. Deregulation of miRNA-mediated pathways may contribute to pathological conditions such as tumors, including hematological cancers, thus suggesting that miRNAs act both as tumor-suppressor genes (TSG) and oncogenes (OG). Here, we provide an overview of the current understanding of the aberration of miRNA biogenesis, activity, and post-transcriptional control in leukemogenesis.

Histone acetyltransferases (HATs) and histone deacetylases (HDACs) are two opposing classes of enzymes, which finely regulate the balance of histone acetylation affecting chromatin packaging and gene expression. Imbalanced acetylation has been associated with carcinogenesis and cancer progression. In contrast to genetic mutations, epigenetic changes are potentially reversible. This implies that epigenetic alterations are amenable to pharmacological interventions. Accordingly, some epigenetic-based drugs (epidrugs) have been approved by the Food and Drug Administration (FDA) and the European Medicines Agency (EMA) for cancer treatment. Here, we focus on the biological features of HDAC inhibitors (HDACis), analyzing the mechanism(s) of action and their current use in clinical practice. (C) 2012 Elsevier Inc. All rights reserved.