HIF-1α suppressing small molecule, LW6, inhibits cancer cell growth by binding to calcineurin b homologous protein 1

Cytotoxicity of alkaline serine protease (ASPNJ) on Jurkat cells and its correlation with changes in the expression of membrane-associated proteins

We aim to study the inhibitory effect of alkaline serine protease (ASPNJ) on lymphocytic leukemia Jurkat cells and its related mechanism through examining the expression of membrane proteins or membrane-associated proteins. MTT assay and trypan blue staining were used to detect the inhibitory effect of ASPNJ on the proliferation and growth of Jurkat cells. Wright-Giemsa staining was used to observe the effect of ASPNJ on the morphology of Jurkat cells. The effect of ASPNJ on Jurkat cell apoptosis was detected by flow cytometry. Two-dimensional electrophoresis-mass spectrometry (2-DE-MS) was used to detect and identify the differentially expressed proteins of Jurkat cells treated with ASPNJ (4 μg/mL, 3 h), of which three were selected and verified by Western blot. ASPNJ significantly inhibited the proliferation of leukemia cells (Raji, U937, and Jurkat), caused obvious morphological changes, and induced apoptosis of Jurkat cells. ASPNJ also increased the sensitivity of Jurkat cells to vincristine (VCR). Seven differentially expressed proteins were obtained through 2DE-MS, of which Peroxiredoxin-6 (PRDX6), Calcium-binding protein (CHP1), and 40S ribosomal protein SA (RPSA) were validated. ASPNJ can cause significant toxic effects on Jurkat cells and enhance the effects of VCR. The mechanism of action of ASPNJ on Jurkat cells may be related to differentially expressed proteins such as PRDX6. This study provides a new experimental basis and direction for antileukemia research.

Hypoxia-Inducible Factor-1: A Novel Therapeutic Target for the Management of Cancer, Drug Resistance, and Cancer-Related Pain

Hypoxia-inducible factor-1 (HIF-1) is a key transcription factor that regulates the transcription of many genes that are responsible for the adaptation and survival of tumor cells in hypoxic environments. Over the past few decades, tremendous efforts have been made to comprehensively understand the role of HIF-1 in tumor progression. Based on the pivotal roles of HIF-1 in tumor biology, many HIF-1 inhibitors interrupting expression, stabilization, DNA binding properties, or transcriptional activity have been identified as potential therapeutic agents for various cancers, yet none of these inhibitors have yet been successfully translated into clinically available cancer treatments. In this review, we briefly introduce the regulation of the HIF-1 pathway and summarize its roles in tumor cell proliferation, angiogenesis, and metastasis. In addition, we explore the implications of HIF-1 in the development of drug resistance and cancer-related pain: the most commonly encountered obstacles during conventional anticancer therapies. Finally, the current status of HIF-1 inhibitors in clinical trials and their perspectives are highlighted, along with their modes of action. This review provides new insights into novel anticancer drug development targeting HIF-1. HIF-1 inhibitors may be promising combinational therapeutic interventions to improve the efficacy of current cancer treatments and reduce drug resistance and cancer-related pain.

Targeted inhibition of the GRK2/HIF-1α pathway is an effective strategy to alleviate synovial hypoxia and inflammation

G-protein coupled receptor (GPCR) kinases (GRKs) and hypoxia-inducible factor-1α (HIF-1α) play key roles in rheumatoid arthritis (RA). Several studies have demonstrated that HIF-1α expression is positively regulated by GRK2, suggesting its posttranscriptional effects on HIF-1α. In this study, we review the role of HIF-1α and GRK2 in RA pathophysiology, focusing on their proinflammatory roles in immune cells and fibroblast-like synoviocytes (FLS).We then introduce several drugs that inhibit GRK2 and HIF-1α, and briefly outline their molecular mechanisms. We conclude by presenting gaps in knowledge and our prospects for the pharmacological potential of targeting these proteins and the relevant downstream signaling pathways.Future research is warranted and paramount for untangling these novel and promising roles for GRK2 and HIF-1α in RA.

Upregulation of MDH1 acetylation by HDAC6 inhibition protects against oxidative stress-derived neuronal apoptosis following intracerebral hemorrhage

Oxidative stress impairs functional recovery after intracerebral hemorrhage (ICH). Histone deacetylase 6 (HDAC6) plays an important role in the initiation of oxidative stress. However, the function of HDAC6 in ICH and the underlying mechanism of action remain elusive. We demonstrated here that HDAC6 knockout mice were resistant to oxidative stress following ICH, as assessed by the MDA and NADPH/NADP+ assays and ROS detection. HDAC6 deficiency also resulted in reduced neuronal apoptosis and lower expression levels of apoptosis-related proteins. Further mechanistic studies showed that HDAC6 bound to malate dehydrogenase 1 (MDH1) and mediated-MDH1 deacetylation on the lysine residues at position 121 and 298. MDH1 acetylation was inhibited in HT22 cells that were challenged with ICH-related damaging agents (Hemin, Hemoglobin, and Thrombin), but increased when HDAC6 was inhibited, suggesting an interplay between HDAC6 and MDH1. The acetylation-mimetic mutant, but not the acetylation-resistant mutant, of MDH1 protected neurons from oxidative injury. Furthermore, HDAC6 inhibition failed to alleviate brain damage after ICH when MDH1 was knockdown. Taken together, our study showed that HDAC6 inhibition protects against brain damage during ICH through MDH1 acetylation.

Resistance to Gemcitabine in Pancreatic Ductal Adenocarcinoma: A Physiopathologic and Pharmacologic Review

Pancreatic ductal adenocarcinoma (PDAC) is a very aggressive tumor with a poor prognosis and inadequate response to treatment. Many factors contribute to this therapeutic failure: lack of symptoms until the tumor reaches an advanced stage, leading to late diagnosis; early lymphatic and hematic spread; advanced age of patients; important development of a pro-tumoral and hyperfibrotic stroma; high genetic and metabolic heterogeneity; poor vascular supply; a highly acidic matrix; extreme hypoxia; and early development of resistance to the available therapeutic options. In most cases, the disease is silent for a long time, andwhen it does become symptomatic, it is too late for ablative surgery; this is one of the major reasons explaining the short survival associated with the disease. Even when surgery is possible, relapsesare frequent, andthe causes of this devastating picture are the low efficacy ofand early resistance to all known chemotherapeutic treatments. Thus, it is imperative to analyze the roots of this resistance in order to improve the benefits of therapy. PDAC chemoresistance is the final product of different, but to some extent, interconnected factors. Surgery, being the most adequate treatment for pancreatic cancer and the only one that in a few selected cases can achieve longer survival, is only possible in less than 20% of patients. Thus, the treatment burden relies on chemotherapy in mostcases. While the FOLFIRINOX scheme has a slightly longer overall survival, it also produces many more adverse eventsso that gemcitabine is still considered the first choice for treatment, especially in combination with other compounds/agents. This review discusses the multiple causes of gemcitabine resistance in PDAC.

Comparison of Gene Expression Profiles of Signet Ring Cell Carcinoma and Poorly Cohesive Carcinoma in Early Gastric Cancer

Introduction:

Although signet ring cell carcinoma (SRC) is a subtype of poorly cohesive carcinoma (PC), the differences in the biological behavior between the 2 morphologically similar carcinomas have not been fully studied. Therefore, we performed transcriptome analysis to evaluate the differences of genetic expressions between SRC and PC.

Methods:

The study group consisted of patients with SRC or PC pathology from patients with early gastric cancer (EGC) whose depth of invasion was localized in the mucosal layer. A total of 18 patients were enrolled. The patients were divided into 3 groups based on their histologic type and lymph node (LN) status. Group 1 consisted of patients with PC and positive LN metastasis, Group 2 consisted of patients with PC without LN metastasis, and Group 3 consisted of patients with SRC without LN metastasis. Transcriptome analysis was performed using the nCounter PanCancer Progression Panel Kit.

Results:

The expression of 77 genes in Group 1 was altered compared to that in normal tissues. The expression of 49 and 13 genes in Groups 2 and 3, respectively, was altered when compared to that in normal tissues. Groups 1 and 2 showed similar genetic expressions. However, Group 3 showed numerous differences in gene expression including Roundabout4 (Robo4) compared to the other groups, especially Group 1.

Conclusion:

Our data suggest that gene expression patterns were different between SRC and PC and expression of ROBO4 may play an important role in the prognosis of SRC and PC type of EGC.

LW1497, an Inhibitor of Malate Dehydrogenase, Suppresses TGF-β1-Induced Epithelial-Mesenchymal Transition in Lung Cancer Cells by Downregulating Slug

LW1497 suppresses the expression of the hypoxia-inducing factor (HIF)-1α inhibiting malate dehydrogenase. Although hypoxia and HIF-1α are known to be important in cancer, LW1497 has not been therapeutically applied to cancer yet. Thus, we investigated the effect of LW1497 on the epithelial-mesenchymal transition (EMT) of lung cancer cells. A549 and H1299 lung cancer cells were induced to undergo via TGF-β1 treatment, resulting in the downregulation of E-cadherin and upregulation of N-cadherin and Vimentin concurrently with increases in the migration and invasion capacities of the cells. These effects of TGF-β1 were suppressed upon co-treatment of the cells with LW1497. An RNA-seq analysis revealed that LW1497 induced differential expression of genes related to hypoxia, RNA splicing, angiogenesis, cell migration, and metastasis in the A549 lung cancer cell lines. We confirmed the differential expression of Slug, an EMT-related transcription factor. Results from Western blotting and RT-PCR confirmed that LW1497 inhibited the expression of EMT markers and Slug. After orthotopically transplanting A549 cancer cells into mice, LW1497 was administered to examine whether the lung cancer progression was inhibited. We observed that LW1497 reduced the area of cancer. In addition, the results from immunohistochemical analyses showed that LW1497 downregulated EMT markers and Slug. In conclusion, LW1497 suppresses cancer progression through the inhibition of EMT by downregulating Slug.

Recent advances in identifying protein targets in drug discovery

Phenotype-based screening has emerged as an alternative route for discovering new chemical entities toward first-in-class therapeutics. However, clarifying their mode of action has been a significant bottleneck for drug discovery. For target protein identification, conventionally bioactive small molecules are conjugated onto solid supports and then applied to isolate target proteins from whole proteome. This approach requires a high binding affinity between bioactive small molecules and their target proteins. Besides, the binding affinity can be significantly hampered after structural modifications of bioactive molecules with linkers. To overcome these limitations, two major strategies have recently been pursued: (1) the covalent conjugation between small molecules and target proteins using photoactivatable moieties or electrophiles, and (2) label-free target identification through monitoring target engagement by tracking the thermal, proteolytic, or chemical stability of target proteins. This review focuses on recent advancements in target identification from covalent capturing to label-free strategies.

Oxygen: viral friend or foe?

The oxygen levels organ and tissue microenvironments vary depending on the distance of their vasculature from the left ventricle of the heart. For instance, the oxygen levels of lymph nodes and the spleen are significantly lower than that in atmospheric air. Cellular detection of oxygen and their response to low oxygen levels can exert a significant impact on virus infection. Generally, viruses that naturally infect well-oxygenated organs are less able to infect cells under hypoxic conditions. Conversely, viruses that infect organs under lower oxygen tensions thrive under hypoxic conditions. This suggests that in vitro experiments performed exclusively under atmospheric conditions ignores oxygen-induced modifications in both host and viral responses. Here, we review the mechanisms of how cells adapt to low oxygen tensions and its impact on viral infections. With growing evidence supporting the role of oxygen microenvironments in viral infections, this review highlights the importance of factoring oxygen concentrations into in vitro assay conditions. Bridging the gap between in vitro and in vivo oxygen tensions would allow for more physiologically representative insights into viral pathogenesis.

Metformin and LW6 impairs pancreatic cancer cells and reduces nuclear localization of YAP1

The poor survival rate of pancreatic cancer is still a major challenge for the clinicians and their patients. In this study, we evaluated the efficacy of metformin, an inhibitor of oxidative phosphorylation, in combination with LW6, which impairs malate dehydrogenase 2 activities, in treating pancreatic cancer cells. We observed that this combinational therapy significantly reduced cell proliferation, migration, and significantly induced cell death when compared to cells treated by each monotherapy or Sham. In addition, we found that the combination of metformin and LW6 increased the phosphorylation of yes-associated protein 1 at serine 127 and attenuated the nuclear localization of this transcription factor. This combinatorial treatment also decreased the level of cellular yes-associated protein 1. This suggests that metformin in combination with LW6 impairs pancreatic cancer cells and reduces nuclear localization of yes-associated protein 1.

Recent advances in the search of BCRP- and dual P-gp/BCRP-based multidrug resistance modulators

The development of multidrug resistance (MDR) is one of the major challenges to the success of chemotherapy treatment of cancer. This phenomenon is often associated with the overexpression of the ATP-binding cassette (ABC) transporters P-gp (P-glycoprotein, ABCB1), multidrug resistance-associated protein 1, ABCC1 and breast cancer resistance protein, ABCG2 (BCRP). These transporters are constitutively expressed in many tissues playing relevant protective roles by the regulation of the permeability of biological membranes, but they are also overexpressed in malignant tissues. P-gp is the first efflux transporter discovered to be involved in cancer drug resistance, and over the years, inhibitors of this pump have been disclosed to administer them in combination with chemotherapeutic agents. Three generations of inhibitors of P-gp have been examined in preclinical and clinical studies; however, these trials have largely failed to demonstrate that coadministration of pump inhibitors elicits an improvement in therapeutic efficacy of antitumor agents, although some of the latest compounds show better results. Therefore, new and innovative strategies, such as the fallback to natural products and the discover of dual activity ligands emerged as new perspectives. BCRP is the most recently ABC protein identified to be involved in multidrug resistance. It is overexpressed in several haematological and solid tumours together with P-gp, threatening the therapeutic effectiveness of different chemotherapeutic drugs. The chemistry of recently described BCRP inhibitors and dual P-gp/BCRP inhibitors, as well as their preliminary pharmacological evaluation are discussed, and the most recent advances concerning these kinds of MDR modulators are reviewed.

"Clicking" Gene Therapeutics: A Successful Union of Chemistry and Biomedicine for New Solutions

The use of nucleic acid, DNA and RNA, based strategies to disrupt gene expression as a therapeutic is quickly emerging. Indeed, synthetic oligonucleotides represent a major component of modern gene therapeutics. However, the efficiency and specificity of intracellular uptake for nonmodified oligonucleotides is rather poor. Utilizing RNA based oligonucleotides as therapeutics is even more challenging to deliver, due to extremely fast enzymatic degradation of the RNAs. RNAs get rapidly degraded in vivo and demonstrate large off-target binding events when they can reach and enter the desired target cells. One approach that holds much promise is the utilization of "click chemistry" to conjugate receptor or cell specific targeting molecules directly to the effector oligonucleotides. We discuss here the applications of the breakthrough technology of CuAAC click chemistry and the immense potential in utilizing "click chemistry" in the development of new age targeted oligonucleotide therapeutics.

Hypoxia-inducible factor-1 (HIF-1) inhibitors from the last decade (2007 to 2016): A "structure-activity relationship" perspective

Tumor hypoxia is a common feature in most solid tumors and is associated with overexpression of the hypoxia response pathway. Overexpression of the hypoxia-inducible factor (HIF-1) protein leads to angiogenesis, metastasis, apoptosis resistance, and many other pro-tumorigenic responses in cancer development. HIF-1 is a promising target in cancer drug development to increase the patient's response to chemotherapy and radiotherapy as well as the survival rate of cancer patients. Since up to 1% of genes are hypoxia-sensitive, a target-specific HIF-1 inhibitor may be a better clinical candidate in cancer drug discovery. Though no HIF-1 inhibitor is clinically available to date, a lot of effort has been applied during the last decade in search of potent HIF-1 inhibitors. In this review, we will summarize the structure-activity relationship of ten different chemotypes reported to be HIF-1 inhibitors in the last decade (2007-2016), their mechanisms of action for HIF-1 inhibition, progress in the way of target-specific inhibitors, and problems associated with current inhibitors. It is anticipated that the results of these research on the medicinal chemistry of HIF-1 inhibitors will provide decent information in the design and development of future inhibitors.

Discovery of LW6 as a new potent inhibitor of breast cancer resistance protein

PURPOSE

The present study aimed to discover a new potent BCRP inhibitor overcoming multidrug resistance.

METHODS

Effects of LW6 on the functional activity and gene expression of two major efflux transporters, BCRP and P-gp, were evaluated by using MDCKII cells overexpressing each transporter (MDCKII-BCRP and MDCKII-MDR1). Its effects on the cytotoxicity and pharmacokinetics of co-administered anticancer drugs were also evaluated in transfected cells and rats, respectively.

RESULTS

In MDCKII-BCRP cells overexpressing BCRP, LW6 enhanced significantly (p < 0.05) the cellular accumulation of mitoxantrone, a BCRP substrate, and was more potent than Ko143, a well-known BCRP inhibitor. LW6 also down-regulated BCRP expression at concentrations of 0.1-10 µM. Furthermore, cells became more susceptible to the cytotoxicity of anticancer drugs in the presence of LW6. The CC50 values of mitoxantrone and doxorubicin were reduced by three- and tenfold, respectively, in MDCKII-BCRP cells, while LW6 did not affect the cytotoxicity of anticancer drugs in MDCKII-mock cells lacking BCRP transporter. Furthermore, LW6 improved the oral exposure of methotrexate by twofold in rats. In contrast to BCRP, LW6 had no inhibition effect on the functional activity and gene expression of P-gp.

CONCLUSION

LW6 was newly identified as a potent BCRP inhibitor and could be useful to reduce the multidrug resistance of cancer cells via the inhibition of BCRP-mediated drug efflux as well as the down-regulation of BCRP expression.

Recent developments and applications of clickable photoprobes in medicinal chemistry and chemical biology

Photoaffinity labeling is a well-known biochemical technique that has grown significantly since the turn of the century, principally due to its combination with bioorthogonal/click chemistry reactions. This review highlights new developments and applications of clickable photoprobes in medicinal chemistry and chemical biology. In particular, recent examples of clickable photoprobes for target identification, activity- or affinity-based protein profiling (ABPP or AfBPP), characterization of sterol– or lipid–protein interactions and characterization of ligand-binding sites are presented.