Effects of suberoylanilide hydroxamic acid (SAHA) combined with paclitaxel (PTX) on paclitaxel-resistant ovarian cancer cells and insights into the underlying mechanisms

Design, synthesis and mechanistic study of new dual targeting HDAC/tubulin inhibitors

Aim: The purpose of this work is to create and synthesize a new class of chemicals: 3-cyano-2-substituted pyridine compounds with expected multitarget inhibition of histone deacetylase (HDAC) and tubulin. Materials & methods: The target compounds (3a-c, 4a-c and 5a-c) were synthesized utilizing 6-(4-methoxyphenyl)-2-oxo-4-(3,4,5-trimethoxyphenyl)-3-cyanopyridine, with various linkers and zinc-binding groups (ZBGs). Results: Most of the tested compounds showed promising growth inhibition, and hydroxamic acid-containing hybrids possessed higher HDAC inhibition than other ZBGs. Compound 4b possessed the highest potency; however, it showed the most tubulin polymerization inhibition. Docking studies displayed good binding into HDAC1 and six pockets and tubulin polymerization protein. Conclusion: Compound 4b could be considered a good antitumor candidate to go further into in vivo and clinical studies.

The Roles of Histone Deacetylases in the Regulation of Ovarian Cancer Metastasis

Ovarian cancer is the most lethal gynecologic malignancy, and metastasis is the major cause of death in patients with ovarian cancer, which is regulated by the coordinated interplay of genetic and epigenetic mechanisms. Histone deacetylases (HDACs) are enzymes that can catalyze the deacetylation of histone and some non-histone proteins and that are involved in the regulation of a variety of biological processes via the regulation of gene transcription and the functions of non-histone proteins such as transcription factors and enzymes. Aberrant expressions of HDACs are common in ovarian cancer. Many studies have found that HDACs are involved in regulating a variety of events associated with ovarian cancer metastasis, including cell migration, invasion, and the epithelial-mesenchymal transformation. Herein, we provide a brief overview of ovarian cancer metastasis and the dysregulated expression of HDACs in ovarian cancer. In addition, we discuss the roles of HDACs in the regulation of ovarian cancer metastasis. Finally, we discuss the development of compounds that target HDACs and highlight their importance in the future of ovarian cancer therapy.

Discovery of chiral 1,4-diarylazetidin-2-one-based hydroxamic acid derivatives as novel tubulin polymerization inhibitors with histone deacetylase inhibitory activity

Tubulin and histone deacetylase have been clinically proven as promising targets for cancer therapy. Herein, we describe the design and synthesis of chiral 1,4-diarylazetidin-2-one-based hydroxamic acids as novel tubulin/HDAC dual inhibitors. Among them, compound 12a was validated to effectively disrupt tubulin polymerization, and exhibited potent HDAC1/8 inhibitory activities. Meanwhile, 12a showed good antiproliferative activities against four tumor cell lines. Further studies showed 12a works through blocking cellular cycle, inducing apoptosis and inhibiting colony formation. In addition, 12a has suitable physicochemical properties and high liver microsomal metabolic stability. Importantly, compound 12a was found to exhibit significant antitumor efficacy in vivo, thus warranting it as a promising tubulin/HDAC dual inhibitor for further development.

Potential of histone deacetylase inhibitors for the therapy of ovarian cancer

Malignant ovarian tumors bear the highest mortality rate among all gynecological cancers. Both late tumor diagnosis and tolerance to available chemotherapy increase patient mortality. Accumulating evidence demonstrates that histone modifications play a key role in cancerization and progression. Histone deacetylases is associated with chromatin condensed structure and transcriptional repression and play a role in chromatin remodeling and epigenetics. Histone deacetylases are promising targets for therapeutic interventions intended to reverse aberrant epigenetic associated with cancer. Therefore, histone deacetylases inhibitors could be used as anti-cancer drugs. Preclinical studies have shown promising outcomes of histone deacetylases inhibitors in ovarian cancer while clinical trials have had mixed results and limited success as monotherapy. Therefore, combination therapy with different anticancer drugs for synergistic effects and newly selective histone deacetylases inhibitors development for lower toxicity are hot issues now. In this review, we summarize the latest studies on the classification and mechanisms of action of histone deacetylase and the clinical application of their inhibitors as monotherapy or combination therapy in ovarian cancer.

Panobinostat Synergistically Enhances the Cytotoxicity of Microtubule Destabilizing Drugs in Ovarian Cancer Cells

Ovarian cancer (OC) is one of the most common gynecologic neoplasia and has the highest mortality rate, which is mainly due to late-stage diagnosis and chemotherapy resistance. There is an urgent need to explore new and better therapeutic strategies. We have previously described a family of Microtubule Destabilizing Sulfonamides (MDS) that does not trigger multidrug-mediated resistance in OC cell lines. MDS bind to the colchicine site of tubulin, disrupting the microtubule network and causing antiproliferative and cytotoxic effects. In this work, a novel microtubule-destabilizing agent (PILA9) was synthetized and characterized. This compound also inhibited OC cell proliferation and induced G2/M cell cycle arrest and apoptosis. Interestingly, PILA9 was significantly more cytotoxic than MDS. Here, we also analyzed the effect of these microtubule-destabilizing agents (MDA) in combination with Panobinostat, a pan-histone deacetylase inhibitor. We found that Panobinostat synergistically enhanced MDA-cytotoxicity. Mechanistically, we observed that Panobinostat and MDA induced α-tubulin acetylation and that the combination of both agents enhanced this effect, which could be related to the observed synergy. Altogether, our results suggest that MDA/Panobinostat combinations could represent new therapeutic strategies against OC.

Suberoylanilide hydroxamic acid suppresses axonal damage and neurological dysfunction after subarachnoid hemorrhage via the HDAC1/HSP70/TDP-43 axis

Increased focus has been placed on the role of histone deacetylase inhibitors as crucial players in subarachnoid hemorrhage (SAH) progression. Therefore, this study was designed to expand the understanding of SAH by exploring the downstream mechanism of the histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA) in SAH. The expression of TDP-43 in patients with SAH and rat models of SAH was measured. Then, western blot analysis, immunofluorescence staining, and transmission electron microscope were used to investigate the in vitro effect of TDP-43 on a neuronal cell model of SAH established by oxyhemoglobin treatment. Immunofluorescence staining and coimmunoprecipitation assays were conducted to explore the relationship among histone deacetylase 1 (HDAC1), heat shock protein 70 (HSP70), and TDP-43. Furthermore, the in vivo effect of HDAC1 on SAH was investigated in rat models of SAH established by endovascular perforation. High expression of TDP-43 in the cerebrospinal fluid of patients with SAH and brain tissues of rat models of SAH was observed, and TDP-43 accumulation in the cytoplasm and the formation of inclusion bodies were responsible for axonal damage, abnormal nuclear membrane morphology, and apoptosis in neurons. TDP-43 degradation was promoted by the HDAC1 inhibitor SAHA via the acetylation of HSP70, alleviating SAH, and this effect was verified in vivo in rat models. In conclusion, SAHA relieved axonal damage and neurological dysfunction after SAH via the HSP70 acetylation-induced degradation of TDP-43, highlighting a novel therapeutic target for SAH.

Epigenetic Regulation of Multidrug Resistance Protein 1 and Breast Cancer Resistance Protein Transporters by Histone Deacetylase Inhibition

Multidrug resistance protein 1 (MDR1, ABCB1, P-glycoprotein) and breast cancer resistance protein (BCRP, ABCG2) are key efflux transporters that mediate the extrusion of drugs and toxicants in cancer cells and healthy tissues, including the liver, kidneys, and the brain. Altering the expression and activity of MDR1 and BCRP influences the disposition, pharmacodynamics, and toxicity of chemicals, including a number of commonly prescribed medications. Histone acetylation is an epigenetic modification that can regulate gene expression by changing the accessibility of the genome to transcriptional regulators and transcriptional machinery. Recently, studies have suggested that pharmacological inhibition of histone deacetylases (HDACs) modulates the expression and function of MDR1 and BCRP transporters as a result of enhanced histone acetylation. This review addresses the ability of HDAC inhibitors to modulate the expression and the function of MDR1 and BCRP transporters and explores the molecular mechanisms by which HDAC inhibition regulates these transporters. While the majority of studies have focused on histone regulation of MDR1 and BCRP in drug-resistant and drug-sensitive cancer cells, emerging data point to similar responses in nonmalignant cells and tissues. Elucidating epigenetic mechanisms regulating MDR1 and BCRP is important to expand our understanding of the basic biology of these two key transporters and subsequent consequences on chemoresistance as well as tissue exposure and responses to drugs and toxicants. SIGNIFICANCE STATEMENT: Histone deacetylase inhibitors alter the expression of key efflux transporters multidrug resistance protein 1 and breast cancer resistance protein in healthy and malignant cells.

Paclitaxel-Loaded Macrophage Membrane Camouflaged Albumin Nanoparticles for Targeted Cancer Therapy

BACKGROUND

Melanoma is the most common symptom of aggressive skin cancer, and it has become a serious health concern worldwide in recent years. The metastasis rate of malignant melanoma remains high, and it is highly difficult to cure with the currently available treatment options. Effective yet safe therapeutic options are still lacking. Alternative treatment options are in great demand to improve the therapeutic outcome against advanced melanoma. This study aimed to develop albumin nanoparticles (ANPs) coated with macrophage plasma membranes (RANPs) loaded with paclitaxel (PTX) to achieve targeted therapy against malignant melanoma.

METHODS

Membrane derivations were achieved by using a combination of hypotonic lysis, mechanical membrane fragmentation, and differential centrifugation to empty the harvested cells of their intracellular contents. The collected membrane was then physically extruded through a 400 nm porous polycarbonate membrane to form macrophage cell membrane vesicles. Albumin nanoparticles were prepared through a well-studied nanoprecipitation process. At last, the two components were then coextruded through a 200 nm porous polycarbonate membrane.

RESULTS

Using paclitaxel as the model drug, PTX-loaded RANPs displayed significantly enhanced cytotoxicity and apoptosis rates compared to albumin nanoparticles without membrane coating in the murine melanoma cell line B16F10. RANPs also exhibited significantly higher internalization efficiency in B16F10 cells than albumin nanoparticles without a membrane coating. Next, a B16F10 tumor xenograft mouse model was established to explore the biodistribution profiles of RANPs, which showed prolonged blood circulation and selective accumulation at the tumor site. PTX-loaded RANPs also demonstrated greatly improved antitumor efficacy in B16F10 tumor-bearing mouse xenografts.

CONCLUSION

Albumin-based nanoscale delivery systems coated with macrophage plasma membranes offer a highly promising approach to achieve tumor-targeted therapy following systemic administration.

ING5-mediated antineuroblastoma effects of suberoylanilide hydroxamic acid

Neuroblastoma is the most common extracranial solid neuroendocrine cancer and is one of the leading causes of death in children. To improve clinical outcomes and prognosis, discovering new promising drugs and targeted medicine is essential. We found that applying Suberoylanilide hydroxamic acid (SAHA; Vorinostat, a histone deacetylase inhibitor) and MG132 (a proteasome inhibitor) to SH‐SY5Y cells synergistically suppressed proliferation, glucose metabolism, migration, and invasion and induced apoptosis and cell cycle arrest. These effects occurred both concentration and time dependently and were associated with the effects observed with inhibitor of growth 5 (ING5) overexpression. SAHA and MG132 treatment increased the expression levels of ING5, PTEN, p53, Caspase‐3, Bax, p21, and p27 but decreased the expression levels of 14‐3‐3, MMP‐2, MMP‐9, ADFP, Nanog, c‐myc, CyclinD1, CyclinB1, and Cdc25c concentration dependently, similar to ING5. SAHA may downregulate miR‐543 and miR‐196‐b expression to enhance the translation of ING5 protein, which promotes acetylation of histones H3 and H4. All three proteins (ING5 and acetylated histones H3 and H4) were recruited to the promoters of c‐myc, Nanog, CyclinD1, p21, and p27 for complex formation, thereby regulating the mRNA expression of downstream genes. ING5 overexpression and SAHA and/or MG132 administration inhibited tumor growth in SH‐SY5Y cells by suppressing proliferation and inducing apoptosis. The expression of acetylated histones H3 and ING5 may be closely linked to the tumor size of neuroblastomas. In summary, SAHA and/or MG132 can synergistically suppress the malignant phenotypes of neuroblastoma cells through the miRNA‐ING5‐histone acetylation axis and via proteasomal degradation, respectively. Therefore, the two drugs may serve as potential treatments for neuroblastoma.

The combination of epigenetic drugs SAHA and HCI-2509 synergistically inhibits EWS-FLI1 and tumor growth in Ewing sarcoma

Purpose

Epigenetic regulation is crucial in mammalian development and maintenance of tissue-cell specific functions. Perturbation of epigenetic balance may lead to alterations in gene expression, resulting in cellular transformation and malignancy. Previous studies in Ewing sarcoma (ES) have shown that the Nucleosome Remodeling Deacetylase (NuRD) complex binds directly to EWS-FLI1 oncoprotein and modulates its transcriptional activity. The role of EWS-FLI1 as a driver of proliferation and transformation in ES is widely known, but the effect of epigenetic drugs on fusion activity remains poorly described. The present study evaluated the combination effects of the histone deacetylases inhibitor suberoylanilide hydroxamic acid (SAHA) and Lysine-specific demethylase1 inhibitor (HCI-2509) on different biological functions in ES and in comparison to monotherapy treatments.

Results

The study of proliferation and cell viability showed a synergistic effect in most ES cell lines analyzed. An enhanced effect was also observed in the induction of apoptosis, together with accumulation of cells in G1 phase and a blockage of the migratory capacity of ES cell lines. Treatment, either in monotherapy or in combination, caused a significant decrease of EWS-FLI1 mRNA and protein levels and this effect is mediated in part by fusion gene promoter regulation. The anti-tumor effect of this combination was confirmed in patient-derived xenograft mouse models, in which only the combination treatment led to a statistically significant decrease in tumor volume.

Conclusions

The combination of SAHA and HCI-2509 is proposed as a novel treatment strategy for ES patients to inhibit the essential driver of this sarcoma and tumor growth.

Selective HDAC inhibition by ACY-241 enhances the activity of paclitaxel in solid tumor models

ACY-241 is a novel, orally available and selective histone deacetylase (HDAC) 6 inhibitor in Phase 1b clinical development in multiple myeloma (NCT 02400242). Like the structurally related drug ACY-1215 (ricolinostat), ACY-241 has the potential for a substantially reduced side effect profile versus current nonselective HDAC inhibitor drug candidates due to reduced potency against Class I HDACs while retaining the potential for anticancer effectiveness. We now show that combination treatment of xenograft models with paclitaxel and either ricolinostat or ACY-241 significantly suppresses solid tumor growth. In cell lines from multiple solid tumor lineages, combination treatment with ACY-241 and paclitaxel enhanced inhibition of proliferation and increased cell death relative to either single agent alone. Combination treatment with ACY-241 and paclitaxel also resulted in more frequent occurrence of mitotic cells with abnormal multipolar spindles and aberrant mitoses, consistent with the observed increase of aneuploid cells. At the molecular level, multipolar mitotic spindle formation was observed to be NuMA-dependent and γ-tubulin independent, suggesting that treatment-induced multipolar spindle formation does not depend on centrosomal amplification. The significantly enhanced efficacy of ACY-241 plus paclitaxel observed here, in addition to the anticipated superior safety profile of a selective HDAC6 inhibitor versus pan-HDAC inhibitors, provides a strong rationale for clinical development of this combination in patients with advanced solid tumors.

SAHA and/or MG132 reverse the aggressive phenotypes of glioma cells: An in vitro and vivo study

To elucidate the anti-tumor effects and molecular mechanisms of SAHA (a histone deacetylase inhibitor) and MG132 (a proteasome inhibitor) on the aggressive phenotypes of glioma cells, we treated U87 and U251 cells with SAHA or/and MG132, and detected phenotypes’ assays with phenotype-related molecules examined. It was found that SAHA or/and MG132 treatment suppressed proliferation in both concentration- and time-dependent manners, inhibited energy metabolism, migration, invasion and lamellipodia formation, and induced G₂ arrest and apoptosis in the glioma cells. The treatment with SAHA increased the expression of acetyl-histones 3 and 4, which were recruited to the promoters of p21, p27, Cyclin D1, c-myc and Nanog to down-regulate their transcriptional levels. Expression of acetyl-histones 3 and 4 was higher in gliomas than normal brain tissues. Both drugs’ exposure suppressed tumor growth in nude mice by inducing apoptosis and inhibiting proliferation, but increased serum aminotransferase and creatinine. These results indicated that SAHA and/or MG132 may suppress the aggressive phenotypes of glioma cells. They might be employed to treat the glioma if both hepatic and renal injuries are prevented.

The in vitro and vivo anti-tumor effects and molecular mechanisms of suberoylanilide hydroxamic acid (SAHA) and MG132 on the aggressive phenotypes of gastric cancer cells

Here, we found that both SAHA and MG132 synergistically inhibited proliferation, glycolysis and mitochondrial oxidization, induced cell cycle arrest and apoptosis in MGC-803 and MKN28 cells. SAHA increased cell migration and invasionat a low concentration. SAHA induced the overexpression of acetyl histone 3 and 4, which were recruited to p21, p27, Cyclin D1, c-myc and nanog promoters to transcriptionally up-regulate the former two and down-regulate the latter three. The expression of acetyl-histone 3 and 4 was increased during gastric carcinogenesis and positively correlated with cancer differentiation. SAHA and MG132 exposure suppressed tumor growth by inhibiting proliferation and inducing apoptosis in nude mice, increased serum ALT and AST levels and decreased hemaglobin level, white blood cell and neutrophil numbers. These data indicated that SAHA and MG132 in vivo and vitro synergistically induced cytotoxicity and apoptosis, suppressed proliferation, growth, migration and invasion of gastric cancer cells. Therefore, they might potentially be employed as chemotherapeutic agents if the hepatic injury and the killing effects of peripheral blood cells are avoided or ameliorated.

IGHG1 promotes motility likely through epithelial-mesenchymal transition in ovarian cancer

Objective

Ovarian cancer (OC) is one of the leading causes of death for female cancer patients. COC166-9 is an OC-specific monoclonal antibody and we have identified immunoglobulin γ-1 heavy chain constant region (IGHG1) as its antigen. We explore the function of IGHG1 in proliferation, apoptosis and motility of OC cells further in this research.

Methods

IGHG1 expression in OC specimens was detected through immunohistochemistry. Real-time quantitative polymerase chain reaction (RT-qPCR) or western blotting assay was used to test IGHG1 expression in OC cells. Viability of OC cells was tested by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Flow cytometry or western blotting assay was used to detect cell cycle and apoptosis. Cellular motility was analyzed by using transwell assay and the markers of epithelial-mesenchymal transition (EMT) were tested through immunoblots.

Results

Although it exerts negligible effect on the viability and apoptosis of OC cells, IGHG1 could promote migration and invasion of malignant cells in vitro. Mechanistically, IGHG1 increases the expression of N-cadherin and Vimentin while decreases E-cadherin expression. Additionally, IGHG1 expression in OC specimens is higher relative to the paired normal counterparts. Further analysis demonstrates that the increased IGHG1 expression correlates positively with the lymph node metastasis of OC.

Conclusions

IGHG1 promotes the motility of OC cells likely through executing the EMT program. Increased IGHG1 expression in OC specimens is associated with the lymph node metastasis.

Dysregulation of Aromatase in Breast, Endometrial, and Ovarian Cancers: An Overview of Therapeutic Strategies

Aromatase is the rate-limiting enzyme in the biosynthesis of estrogens, which play crucial roles on a spectrum of developmental and physiological processes. The biological actions of estrogens are classically mediated by binding to two estrogen receptors (ERs), ERα and ERβ. Encoded by the cytochrome P450, family 19, subfamily A, polypeptide 1 (CYP19A1) gene, aromatase is expressed in a wide variety of tissues, as well as benign and malignant tumors, and is regulated in a pathway- and tissue-specific manner. Overexpression of aromatase, leading to elevated systemic levels of estrogen, is unequivocally linked to the pathogenesis and growth of a number malignancies, including breast, endometrium, and ovarian cancers. Aromatase inhibitors (AIs) are routinely used to treat estrogen-dependent breast cancers in postmenopausal women; however, their roles in endometrial and ovarian cancers remain obscure. While AI therapy is effective in hormone sensitive cancers, they diminish estrogen production throughout the body and, thus, generate undesirable side effects. Despite the effectiveness of AI therapy, resistance to endocrine therapy remains a major concern and is the leading cause of cancer death. Considerable advances, toward mitigating these issues, have evolved in conjunction with a number of histone deacetylase (HDAC) inhibitors for countering an assortment of diseases and cancers, including the aforesaid malignancies. HDACs are a family of enzymes that are frequently dysregulated in human tumors. This chapter will discuss the current understanding of aberrant regulation and expression of aromatase in breast, endometrial, and ovarian cancers, and potential therapeutic strategies for prevention and treatment of these life-threatening diseases.

Influence of a novel histone deacetylase inhibitor panobinostat (LBH589) on the growth of ovarian cancer

Background

Pre-clinical studies have demonstrated that natural and synthetic histone deacetylase (HDAC) inhibitors can impede the in vitro and in vivo growth of cell lines from a variety of gynecologic and other malignancies. We investigated the anti-tumor activity of panobinostat (LBH589) both in vitro and in vivo as either a single agent or in combination with conventional cytotoxic chemotherapy using patient-derived xenograft (PDX) models of primary serous ovarian tumors.

Methods

The ovarian cancer cell lines OVCAR8, SKOV3 and their paclitaxel-resistant derivatives OVCAR8-TR and SKOV3-TR were treated with increasing doses of LBH589. The effect of LBH589 on cell viability was assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Serially transplanted primary human high-grade serous ovarian adenocarcinoma tissue was utilized to generate xenografts in 6-week old female NOD/SCID mice. The mice were then randomized into one of 4 treatment groups: (1) vehicle control; (2) paclitaxel and carboplatin (P/C); (3) LBH589; or (4) P/C + LBH589. Mice were treated for 21 days and tumor volumes and mouse weights were obtained every 3 days. These experiments were performed in triplicate with three different patient derived tumors. Wilcoxan rank-sum testing was utilized to assess tumor volume differences.

Results

In vitro treatment with LBH589 significantly reduced the viability of both taxol-sensitive and taxol-resistant ovarian cancer cell lines (p < 0.01). In vivo treatment with LBH589 alone appeared tumorstatic and reduced tumor growth when compared to vehicle treatment (p < 0.007) after 21 days. This single agent activity was confirmed in two additional experiments with other PDX tumors (p < 0.03, p < 0.05). A potential additive effect of LBH589 and P/C, manifested as enhanced tumor regression with the addition of LBH589 compared to vehicle (p < 0.02), in one of the three analyzed serous PDX models.

Conclusions

Our findings suggest that pan-HDAC inhibition with panobinostat precludes the growth of ovarian cancer cell lines in vitro and PDXs in vivo. Added benefit of LBH589 to standard P/C therapy was observed in one of three PDX models suggesting improved response in a subset of serous ovarian cancers.