Ruxolitinib induces autophagy in chronic myeloid leukemia cells

The Role of Autophagy in Type 2 Diabetic Kidney Disease Management

Diabetic kidney disease (DKD), or diabetic nephropathy (DN), is one of the most prevalent complications of type 2 diabetes mellitus (T2DM) and causes severe burden on the general welfare of T2DM patients around the world. While several new agents have shown promise in treating this condition and potentially halting the progression of the disease, more work is needed to understand the complex regulatory network involved in the disorder. Recent studies have provided new insights into the connection between autophagy, a physiological metabolic process known to maintain cellular homeostasis, and the pathophysiological pathways of DKD. Typically, autophagic activity plays a role in DKD progression mainly by promoting an inflammatory response to tissue damage, while both overactivated and downregulated autophagy worsen disease outcomes in different stages of DKD. This correlation demonstrates the potential of autophagy as a novel therapeutic target for the disease, and also highlights new possibilities for utilizing already available DN-related medications. In this review, we summarize findings on the relationship between autophagy and DKD, and the impact of these results on clinical management strategies.

JAK/STAT pathway: Extracellular signals, diseases, immunity, and therapeutic regimens

Janus kinase/signal transduction and transcription activation (JAK/STAT) pathways were originally thought to be intracellular signaling pathways that mediate cytokine signals in mammals. Existing studies show that the JAK/STAT pathway regulates the downstream signaling of numerous membrane proteins such as such as G-protein-associated receptors, integrins and so on. Mounting evidence shows that the JAK/STAT pathways play an important role in human disease pathology and pharmacological mechanism. The JAK/STAT pathways are related to aspects of all aspects of the immune system function, such as fighting infection, maintaining immune tolerance, strengthening barrier function, and cancer prevention, which are all important factors involved in immune response. In addition, the JAK/STAT pathways play an important role in extracellular mechanistic signaling and might be an important mediator of mechanistic signals that influence disease progression, immune environment. Therefore, it is important to understand the mechanism of the JAK/STAT pathways, which provides ideas for us to design more drugs targeting diseases based on the JAK/STAT pathway. In this review, we discuss the role of the JAK/STAT pathway in mechanistic signaling, disease progression, immune environment, and therapeutic targets.

Ruxolitinib enhances cytotoxic and apoptotic effects of temozolomide on glioblastoma cells by regulating WNT signaling pathway-related genes

Although temozolomide is the primary chemotherapeutic agent in glioblastoma, current studies have focused on its combinational applications to overcome resistance by targeting multiple pathways. JAK/STAT and WNT are among the essential cancer-related signaling pathways. Ruxolitinib, the first approved JAK1/2 inhibitor, has promise in glioblastoma with its blood-brain barrier (BBB) crossing ability. The mentioned study aims to evaluate the anti-cancer potential of ruxolitinib individually and in combination with temozolomide on glioblastoma cells, brain cancer stem cells (BCSCs), and BBB-forming healthy cells. It also intends to determine the effects of JAK inhibitor treatment in combination with temozolomide on WNT signaling, which is known to cross-talk with the JAK/STAT pathway. The U87MG, BCSC, and HBMEC cell lines were the in vitro models. The cytotoxic and apoptotic effects of ruxolitinib and the combination were determined by the WST-1 test and Annexin V assay, respectively. The expression level changes of WNT signaling pathway genes caused by ruxolitinib and the combination treatments were defined by the qRT-PCR method. Network analysis of significantly upregulated and downregulated genes was performed via the GO KEGG pathway enrichment module of the String V11.5 database. The IC₅₀ value of the ruxolitinib on U87MG glioblastoma cells was determined as 94.07 µM at 24th h. The combination of temozolomide and ruxolitinib had a synergistic effect on U87MG cells at 24th h. The combination index (CI) was determined as 0.796, and ED₆₀ values of ruxolitinib and temozolomide were determined as 89.75 and 391.48 µM, respectively. Ruxolitinib improves the apoptotic effect of temozolomide on glioblastoma cells and brain cancer stem cells. Ruxolitinib regulates the WNT signaling pathway both individually and in combination with temozolomide. Our study indicates the potential of ruxolitinib to increase the cytotoxic and apoptotic activity of temozolomide in glioblastoma cells, also considering CSCs and healthy BBB-forming cells. As supported by gene expression and network analyses, the BBB-crossing agent ruxolitinib promises the potential to increase the efficacy of temozolomide in glioblastoma by affecting multiple signaling pathways in both cancer cells and CSCs.

JAK/STAT pathway promotes the progression of diabetic kidney disease via autophagy in podocytes

Diabetic kidney disease (DKD) is one of the major microvascular complications of diabetes and an important cause of end-stage renal disease. Previous studies have shown that the damage to podocyte autophagy is related to the pathogenesis of DKD, and this damage is closely mediated by the Janus kinase (JAK)/signal transductors and the transcription (STAT) signaling pathway. Here, the underlying molecular mechanism of the JAK/STAT signaling pathway regulating podocyte autophagy was investigated. In the present study, compared to controls, DKD mice showed glomerular hypertrophy, increased kidney weight/weight ratio, and increased urinary protein levels, as well as decreased desmin and synaptopodin expression. Meanwhile, levels of triglyceride, total cholesterol, reduced glutathione, and malondialdehyde were also increased in the serum of DKD mice. Further, a lower number of autophagosomes, reduced expression of MAP1LC3 (LC3) in glomeruli, and increased expression of JAK/STAT pathway-related proteins, namely JAK1, JAK2, STAT1, STAT3, STAT5, and STAT6, were observed in DKD mice. In the in vitro experiments, we observed impaired autophagy, enhanced apoptosis, and activated JAK/STAT pathway in podocytes under high glucose conditions. Studies using ruxolitinib inhibitors have showed that suppression of the JAK/STAT pathway in podocytes subjected to high glucose could increase autophagic flux and autophagy-related protein expression. Taken together, the present study demonstrates that high glucose inhibits autophagy by activating the JAK/STAT pathway in mice and podocytes, thereby preventing the efficient removal of damaged proteins and organelles from the body to prevent apoptosis, and ultimately aggravating the progression of podocyte injury and DKD.

Ruxolitinib Regulates the Autophagy Machinery in Multiple Myeloma Cells

BACKGROUND

Ruxolitinib is a selective JAK1/2 inhibitor approved by the FDA for myelofibrosis in 2014 and nowadays, comprehensive investigations on the potential of the agent as a targeted therapy for haematological malignancies are on the rise. In multiple myeloma which is a cancer of plasma cells, the Interleukin- 6/JAK/STAT pathway is emerging as a therapeutic target since the overactivation of the pathway is associated with poor prognosis.

OBJECTIVE

In this study, our purpose was to discover the potential anticancer effects of ruxolitinib in ARH-77 multiple myeloma cell line compared to NCI-BL 2171 human healthy B lymphocyte cell line.

METHODS

Cytotoxic effects of ruxolitinib in ARH-77 and NCI-BL 2171 cells were determined via WST-1 assay. The autophagy mechanism induced by ruxolitinib measured by detecting autophagosome formation was investigated. Apoptotic effects of ruxolitinib were analyzed with Annexin V-FITC Detection Kit and flow cytometry. We performed RT-qPCR to demonstrate the expression changes of the genes in the IL-6/JAK/STAT pathway in ARH-77 and NCI-BL 2171 cells treated with ruxolitinib.

RESULTS

We identified the IC50 values of ruxolitinib for ARH-77 and NCI-BL 2171 as 20.03 and 33.9μM at the 72nd hour, respectively. We showed that ruxolitinib induced autophagosome accumulation by 3.45 and 1.70 folds in ARH-77 and NCI-BL 2171 cells compared to the control group, respectively. Treatment with ruxolitinib decreased the expressions of IL-6, IL-18, JAK2, TYK2, and AKT genes, which play significant roles in MM pathogenesis.

CONCLUSION

All in all, ruxolitinib is a promising agent for the regulation of the IL-6/JAK/STAT pathway and interferes with the autophagy mechanism in MM.

Enzyme-based autophagy in anti-neoplastic management: From molecular mechanisms to clinical therapeutics

Autophagy is an evolutionarily conserved self-cannibalization process commonly found in all eukaryotic cells. Through autophagy, long-lived or damaged organelles, superfluous proteins, and pathogens are sequestered and encapsulated into the double-membrane autophagosomes prior to fusion with lysosomes for ultimate degradation and recycling. Given that autophagy is deemed both protective and detrimental in malignancies, the clinical therapeutic utilization of autophagy modulators in cancer has attracted immense attentions over the past decades. Dependence of tumor cells on autophagy during amino acid insufficiency or deprivation has prompted us to explore the underlying autophagy regulatory mechanisms to inject amino acid degrading enzymes and enzyme-based strategies into therapeutic maneuvers of autophagy in cancer.

SOX18 Affects Cell Viability, Migration, Invasiveness, and Apoptosis in Hepatocellular Carcinoma (HCC) Cells by Participating in Epithelial-to-Mesenchymal Transition (EMT) Progression and Adenosine Monophosphate Activated Protein Kinase (AMPK)/Mammalian Target of Rapamycin (mTOR)

Background

Hepatocellular carcinoma (HCC) is one of the most common malignancies around the world. It has been verified that the expression of SOX18 is correlated to poor clinical prognosis in patients with ovarian cancer, non-small cell lung cancer, or breast invasive ductal carcinoma. However, the expression pattern and biological function of SOX18 in HCC tissues remains unclear. In this study, we set out to investigate the associated biological function and potential molecular mechanism of the SOX18 gene in HCC cells.

Material/Methods

The mRNA and protein expression levels of experimental related genes were detected by real-time polymerase chain reaction and western blotting assay, respectively. The MTT method was used to assess cell viability, and cell apoptosis analysis was performed by means of FACScan flow cytometry. Wound-healing assay and Transwell analysis were performed to evaluate the ability of cell migration and invasiveness, respectively.

Results

SOX18 was highly expressed in various HCC cell lines. In addition, SOX18 promoted cell viability, migration, and invasion and simultaneously induce cell apoptosis. SOX18 promoted epithelial-to-mesenchymal transition (EMT) progression, and SOX18 downregulation activated the autophagy signaling pathway AMPK/mTOR in HCC cells.

Conclusions

SOX18 downregulation in HCC cells suppressed cell viability and metastasis, induced cell apoptosis and hindered the occurrence and progression of tumor cells by participating in the EMT process and regulating the autophagy signaling pathway AMPK/mTOR.

Autophagy inhibition potentiates ruxolitinib-induced apoptosis in JAK2V617F cells

JAK2^V617F can mimic growth factor signaling, leading to PI3K/AKT/mTOR activation and inhibition of autophagy. We hypothesized that selective inhibition of JAK1/2 by ruxolitinib could induce autophagy and limit drug efficacy in myeloproliferative neoplasms (MPN). Therefore, we investigated the effects of ruxolitinib treatment on autophagy-related genes and cellular processes, to determine the potential benefit of autophagy inhibitors plus ruxolitinib in JAK2^V617F cells, and to verify the frequency and clinical impact of autophagy-related gene mutations in patients with MPNs. In SET2 JAK2^V617F cells, ruxolitinib treatment induced autophagy and modulated 26 out of 79 autophagy-related genes. Ruxolitinib treatment reduced the expressions of important autophagy regulators, including mTOR/p70S6K/4EBP1 and the STAT/BCL2 axis, in a dose- and time-dependent manner. Pharmacological inhibition of autophagy was able to significantly suppress ruxolitinib-induced autophagy and increased ruxolitinib-induced apoptosis. Mutations in autophagy-related genes were found in 15.5% of MPN patients and were associated with increased age and a trend towards worse survival. In conclusion, ruxolitinib induces autophagy in JAK2^V617F cells, potentially by modulation of mTOR-, STAT- and BCL2-mediated signaling. This may lead to inhibition of apoptosis. Our results suggest that the combination of ruxolitinib with pharmacological inhibitors of autophagy, such as chloroquine, may be a promising strategy to treat patients with JAK2^V617F-mutated MPNs.

Epigenetic modifications in chronic myeloid leukemia cells through ruxolitinib treatment

Chronic myeloid leukemia is a clonal malignancy of hematopoietic stem cell that is characterized by the occurrence of t(9;22)(q34;q11.2) translocation, named Philadelphia chromosome. Ruxolitinib is a powerful Janus tyrosine kinase 1 and 2 inhibitor that is used for myelofibrosis treatment. DNA-histone connection mediates a wide range of genes that code methylation, demethylation, acetylation, deacetylation, ubiquitination, and phosphorylation enzymes. Epigenetic modifications regulate chromatin compactness, which plays pivotal roles in critical biological processes including the transcriptional activity and cell proliferation as well as various pathological mechanisms, including CML. This study is aimed to determine the alterations of the expression levels of epigenetic modification-related genes after ruxolitinib treatment. Total RNA was isolated from K-562 cells treated with the IC₅₀ value of ruxolitinib and untreated K-562 control cells. A reverse transcription procedure was performed for complementary DNA synthesis, and gene expressions were detected by real-time polymerase chain reaction compared with the untreated cells. Ruxolitinib treatment caused a significant alteration in the expression levels of epigenetic regulation-related genes in K-562 cells. Our novel results suggested that ruxolitinib has inhibitor effects on epigenetic modification-regulator genes.

Mechanisms for mTORC1 activation and synergistic induction of apoptosis by ruxolitinib and BH3 mimetics or autophagy inhibitors in JAK2-V617F-expressing leukemic cells including newly established PVTL-2

The activated JAK2-V617F mutant is very frequently found in myeloproliferative neoplasms (MPNs), and its inhibitor ruxolitinib has been in clinical use, albeit with limited efficacies. Here, we examine the signaling mechanisms from JAK2-V617F and responses to ruxolitinib in JAK2-V617F-positive leukemic cell lines, including PVTL-2, newly established from a patient with post-MPN secondary acute myeloid leukemia, and the widely used model cell line HEL. We have found that ruxolitinib downregulated the mTORC1/S6K/4EBP1 pathway at least partly through inhibition of the STAT5/Pim-2 pathway with concomitant downregulation of c-Myc, MCL-1, and BCL-xL as well as induction of autophagy in these cells. Ruxolitinib very efficiently inhibited proliferation but only modestly induced apoptosis. However, inhibition of BCL-xL/BCL-2 by the BH3 mimetics ABT-737 and navitoclax or BCL-xL by A-1331852 induced caspase-dependent apoptosis involving activation of Bak and Bax synergistically with ruxolitinib in HEL cells. On the other hand, the putative pan-BH3 mimetic obatoclax as well as chloroquine and bafilomycin A1 inhibited autophagy at its late stage and induced apoptosis in PVTL-2 cells synergistically with ruxolitinib. The present study suggests that autophagy as well as the anti-apoptotic BCL-2 family members, regulated at least partly by the mTORC1 pathway downstream of STAT5/Pim-2, protects JAK2-V617F-positive leukemic cells from ruxolitinib-induced apoptosis depending on cell types and may contribute to development of new strategies against JAK2-V617F-positive neoplasms.

Ruxolitinib combined with vorinostat suppresses tumor growth and alters metabolic phenotype in hematological diseases

JAK-2 dysregulation plays an important role as an oncogenic driver, and is thus a promising therapeutic target in hematological malignancies. Ruxolitinib is a pyrrolo[2.3-d]pyrimidine derivative with inhibitory activity against JAK1 and JAK2, moderate activity against TYK2, and minor activity against JAK3. Vorinostat is an HDAC inhibitor that reduces JAK-2 expression, thus affecting JAK-2 mRNA expression and increasing JAK-2 proteasomal deterioration. Here we hypothesized that the combination of ruxolitinib and vorinostat could have synergistic effects against hematological disease. We tested combinations of low doses of ruxolitinib and vorinostat in 12 cell lines, and observed highly synergistic cytotoxic action in six cell lines, which was maintained for up to 120 h in the presence of stromal cells. The sensitivity of the six cell lines may be explained by the broad effects of the drug combination, which can affect various targets. Treatment with the combination of ruxolitinib and vorinostat appeared to induce a possible reversal of the Warburg effect, with associated ROS production, apoptotic events, and growth inhibition. Decreased glucose metabolism may have markedly sensitized the six more susceptible cell lines to combined treatment. Therapeutic inhibition of the JAK/STAT pathway seems to offer substantial anti-tumor benefit, and combined therapy with ruxolitinib and vorinostat may represent a promising novel therapeutic modality for hematological neoplasms.

An Unbiased High-Throughput Screen to Identify Novel Effectors That Impact on Cardiomyocyte Aggregate Levels

RATIONALE

Postmitotic cells, such as cardiomyocytes, seem to be particularly susceptible to proteotoxic stimuli, and large, proteinaceous deposits are characteristic of the desmin-related cardiomyopathies and crystallin cardiomyopathic diseases. Increased activity of protein clearance pathways in the cardiomyocyte, such as proteasomal degradation and autophagy, has proven to be beneficial in maintaining cellular and cardiac function in the face of multiple proteotoxic insults, holding open the possibility of targeting these processes for the development of effective therapeutics.

OBJECTIVE

Here, we undertake an unbiased, total genome screen for RNA transcripts and their protein products that affect aggregate accumulations in the cardiomyocytes.

METHODS AND RESULTS

Primary mouse cardiomyocytes that accumulate aggregates as a result of a mutant CryAB (αB-crystallin) causative for human desmin-related cardiomyopathy were used for a total genome-wide screen to identify gene products that affected aggregate formation. We infected cardiomyocytes using a short hairpin RNA lentivirus library in which the mouse genome was represented. The screen identified multiple candidates in many cell signaling pathways that were able to mediate significant decreases in aggregate levels.

CONCLUSIONS

Subsequent validation of one of these candidates, Jak1 (Janus kinase 1), a tyrosine kinase of the nonreceptor type, confirmed the usefulness of this approach in identifying previously unsuspected players in proteotoxic processes.

Anti-myeloma effects of ruxolitinib combined with bortezomib and lenalidomide: A rationale for JAK/STAT pathway inhibition in myeloma patients

JAK proteins have been linked with survival and proliferation of multiple myeloma (MM) cells; therefore, JAK inhibition could be a therapeutic strategy for MM. We evaluated JAK1 and JAK2 expression in MM patients and the effects of JAK/STAT pathway inhibition on apoptosis, cell cycle, gene and protein expression in RPMI-8226 and U266 MM cell lines. 57% of patients presented overexpression of JAK2 and 27%, of JAK1. After treatment with ruxolitinib and bortezomib, RPMI-8226 and U266 presented 50% of cells in late apoptosis, reduction of anti-apoptotic genes expression and higher number of cells in SubG0 phase. Co-culture with stromal cells protected RPMI-8226 cells from apoptosis, which was reversed by lenalidomide addition. Combination of ruxolitinib, bortezomib and lenalidomide induced 72% of cell death, equivalent to bortezomib, lenalidomide and dexamethasone, combination used in clinical practice. Many JAK/STAT pathway genes, after treatment, had their expression reduced, mainly in RPMI-8226, with insignificant changes in U266. In this scenario, JAK/STAT pathway could pose as a new therapeutic target to be exploited, since it is constitutively active and contributes to survival of MM tumor cells.