PIM inhibitor SMI-4a induces cell apoptosis in B-cell acute lymphocytic leukemia cells via the HO-1-mediated JAK2/STAT3 pathway

Mutant PIK3CA as a negative predictive biomarker for treatment with a highly selective PIM1 inhibitor in human colon cancer

Significant improvement in targeted therapy for colorectal cancer (CRC) has occurred over the past few decades since the approval of the EGFR inhibitor cetuximab. However, cetuximab is used only for patients possessing the wild-type oncogene KRAS, NRAS, and BRAF, and even most of these eventually acquire therapeutic resistance, via activation of parallel oncogenic pathways such as RAS-MAPK or PI3K/Akt/mTOR. The two aforementioned pathways also contribute to the development of therapeutic resistance in CRC patients, due to compensatory and feedback mechanisms. Therefore, combination drug therapies (versus monotherapy) targeting these multiple pathways may be necessary for further efficacy against CRC. In this study, we identified PIK3CA mutant (PIK3CA MT) as a determinant of resistance to SMI-4a, a highly selective PIM1 kinase inhibitor, in CRC cell lines. In CRC cell lines, SMI-4a showed its effect only in PIK3CA wild type (PIK3CA WT) cell lines, while PIK3CA MT cells did not respond to SMI-4a in cell death assays. In vivo xenograft and PDX experiments confirmed that PIK3CA MT is responsible for the resistance to SMI-4a. Inhibition of PIK3CA MT by PI3K inhibitors restored SMI-4a sensitivity in PIK3CA MT CRC cell lines. Taken together, these results demonstrate that sensitivity to SMI-4a is determined by the PIK3CA genotype and that co-targeting of PI3K and PIM1 in PIK3CA MT CRC patients could be a promising and novel therapeutic approach for refractory CRC patients.

Targeting Pim kinases in hematological cancers: molecular and clinical review

Decades of research has recognized a solid role for Pim kinases in lymphoproliferative disorders. Often up-regulated following JAK/STAT and tyrosine kinase receptor signaling, Pim kinases regulate cell proliferation, survival, metabolism, cellular trafficking and signaling. Targeting Pim kinases represents an interesting approach since knock-down of Pim kinases leads to non-fatal phenotypes in vivo suggesting clinical inhibition of Pim may have less side effects. In addition, the ATP binding site offers unique characteristics that can be used for the development of small inhibitors targeting one or all Pim isoforms. This review takes a closer look at Pim kinase expression and involvement in hematopoietic cancers. Current and past clinical trials and in vitro characterization of Pim kinase inhibitors are examined and future directions are discussed. Current studies suggest that Pim kinase inhibition may be most valuable when accompanied by multi-drug targeting therapy.

Carvedilol exhibits anti-acute T lymphoblastic leukemia effect in vitro and in vivo via inhibiting β-ARs signaling pathway

An increasing number of studies have focus upon β-adrenergic receptor blockers and their anti-tumor effects. However, the use of Carvedilol (CVD), the third generation β-AR blocker, has not been explored for use against T-ALL. In this study, the level of β-ARs was explored in pediatric T-ALL patients. Moreover, the antitumor effects of CVD against T-ALL were assessed in vitro and in vivo, and the underlying mechanisms were investigated. The viability of T-ALL cells following CVD treatment was detected using a CCK-8 assay, and the apoptotic and cell cycle effects were measured using flow cytometry. The protein levels of β-ARs, cAMP, Epac, JAK2, STAT3, p-STAT3, PI3K, p-PI3K, AKT, p-AKT, mTOR, cyclin D1, PCNA, and cleaved caspase-3 were assessed by Western blotting. In vivo experiments were used to investigate the effect of CVD on T-ALL growth in mice. The results indicated that β-ARs were highly expressed in the newly diagnosed T-ALL cells when compared to those in the control group (P < 0.05). In vitro, CVD significantly inhibited T-ALL cell viability, promoted apoptosis and blocked the G0/G1 phase of cell cycle. After CVD treatment, the protein levels of β-ARs, cAMP, Epac, PI3K, p-PI3K, AKT, p-AKT, mTOR, JAK2, STAT3, p-STAT3, cyclin D1 and PCNA were significantly downregulated (P < 0.05); whereas cleaved caspase-3 was significantly upregulated (P < 0.05). In vivo, the volume and weight of the xenograft tumors were significantly decreased in the CVD group (P < 0.05). CVD promoted xenograft tumor apoptosis and reduced the proportion of CEM-C1 cells in murine peripheral blood and bone marrow (P < 0.05). Our results demonstrate that β-ARs are expressed in T-ALL. CVD has a strong antitumor effect against T-ALL and inhibits β-AR associated signaling pathways. Therefore, CVD may provide a potential therapy for T-ALL.

Overexpressed mitogen-and stress-activated protein kinase 1 promotes the resistance of cytarabine in acute myeloid leukemia through brahma related gene 1-mediated upregulation of heme oxygenase-1

Drug resistance remains a major challenge in the current treatment of acute myeloid leukemia (AML). Finding specific molecules responsible for mediating drug resistance in AML contributes to the effective reversal of drug resistance. Recent studies have found that mitogen- and stress-activated protein kinase 1 (MSK1) is of great significance in the occurrence and development of tumors. In the current study, MSK1 was found highly expressed in drug-resistant AML patients. Heme oxygenase-1 (HO-1) has been previously validated to be associated with drug resistance in AML. Our study revealed a positive correlation between MSK1 and HO-1 in patient samples. In vitro experiments revealed that the sensitivity of AML cell lines THP-1 and U937 to cytarabine (Ara-C) significantly decreased after overexpression of MSK1. Meanwhile, downregulation of MSK1 by siRNA transfection or treatment of pharmacological inhibitor SB-747651A in AML cell lines and primary AML cells enhanced the sensitivity to Ara-C. Flow cytometry analysis showed that downregulation of MSK1 in AML cells accelerated apoptosis and arrested cell cycle progression in G0/G1 phase. However, the increased cell sensitivity induced by MSK1 downregulation was reversed by the induction of HO-1 inducer Hemin. Through further mechanism exploration, real-time PCR, immunofluorescence and Western blot analysis demonstrated that brahma related gene 1 (BRG1) was involved in the regulatory effect of MSK1 on HO-1. High expression of MSK1 could promote the resistance of AML through BRG1-mediated upregulation of HO-1. Downregulation of MSK1 enhanced the sensitivity of AML cells to Ara-C. Our findings provide novel ideas for developing effective anti-AML targets.

Butyric Acid Protects Against Renal Ischemia-Reperfusion Injury by Adjusting the Treg/Th17 Balance via HO-1/p-STAT3 Signaling

Immune regulation plays a vital role in ischemia-reperfusion injury (IRI). Butyric acid (BA) has immunomodulatory effects in many diseases, but its immunomodulatory effects during renal IRI are still unclear. Our research shows that BA protected against IRI and significantly improved renal IRI in vivo. In vitro studies showed that BA inhibits Th17 cell differentiation and induces Treg cell differentiation. Mechanism studies have shown that heme oxygenase 1 (HO-1)/STAT3 signaling pathway was involved in the inhibitory effect of BA on Th17 cell differentiation. HO-1 inhibitors can significantly rescue the BA-mediated inhibition of Th17 cell differentiation. We confirmed that BA promotes the differentiation of Th17 cells into Treg cells by regulating the pathway and reduces renal IRI.

Protein kinase PIM2: A simple PIM family kinase with complex functions in cancer metabolism and therapeutics

PIM2 (proviral integration site for Moloney murine leukemia virus 2) kinase plays an important role as an oncogene in multiple cancers, such as leukemia, liver, lung, myeloma, prostate and breast cancers. PIM2 is largely expressed in both leukemia and solid tumors, and it promotes the transcriptional activation of genes involved in cell survival, cell proliferation, and cell-cycle progression. Many tumorigenic signaling molecules have been identified as substrates for PIM2 kinase, and a variety of inhibitors have been developed for its kinase activity, including SMI-4a, SMI-16a, SGI-1776, JP11646 and DHPCC-9. Here, we summarize the signaling pathways involved in PIM2 kinase regulation and PIM2 mechanisms in various neoplastic diseases. We also discuss the current status and future perspectives for the development of PIM2 kinase inhibitors to combat human cancer, and PIM2 will become a therapeutic target in cancers in the future.

HDAC3 Silencing Enhances Acute B Lymphoblastic Leukaemia Cells Sensitivity to MG-132 by Inhibiting the JAK/Signal Transducer and Activator of Transcription 3 Signaling Pathway

PURPOSE

HDAC3, which is associated with smurf2, has been shown to be associated with poor prognosis in B-ALL. This study examined the efficacy of targeting HDAC3 combined with MG-132 as a possible therapeutic strategy for B-ALL patients.

METHODS

Real-time PCR and western blot were used to measure the expression of smurf2 and HDAC3 from B-ALL patients bone marrow samples. Sup-B15 and CCRF-SB cells were treated with MG-132, small interfering RNA of smurf2 or HDAC3. A plasmid designed to up-regulate smurf2 expression was transfected into B-ALL cells. Flow cytometry and western blot were used to measure variation due to these treatments in terms of apoptosis and cell cycle arrest.

RESULTS

Expression of Smurf2 and HDAC3 mRNA were inversely related in B-ALL patients. Up-regulation of smurf2 or MG-132 influenced HDAC3, further inhibiting the JAK/signal transducer and activator of transcription 3 (STAT3) signal pathway and inducing apoptosis in B-ALL cells. When we treated Sup-B15 and CCRF-SB cells with siHDAC3 and MG-132 for 24 h, silencing HDAC3 enhanced the apoptosis rate induced by MG-132 in B-ALL cells and further inhibited the JAK/STAT3 pathway. Furthermore, MG-132 was observed to cause G2/M phase arrest in B-ALL cells and inhibited the JAK/STAT3 pathway, leading to apoptosis.

CONCLUSIONS

Silencing of HDAC3 enhanced the sensitivity of B-ALL cells to MG-132. The combination of targeting HDAC3 and MG-132 may provide a new avenue for clinical treatment of acute B lymphocytic leukaemia and improve the poor survival of leukaemia patients.

Overexpression of heme oxygenase-1 in bone marrow stromal cells promotes multiple myeloma resistance through the JAK2/STAT3 pathway

AIMS

Bone marrow stromal cells (BMSCs) have been reported to interact with multiple myeloma (MM) and exert a vital function of the survival of MM cells. Heme oxygenase-1 (HO-1), a cytoprotective enzyme, has the potential to become a hematological malignancies targeted gene. This study aimed to investigate the role of HO-1 in MM resistance of BMSCs and its possible mechanisms.

MAIN METHODS

In this study, the expression of related proteins was detected by RT-qPCR and Western blot. HO-1 expression was regulated by lentivirus transfection. Cell viability and apoptosis were detected by Flow cytometry and CCK-8. Cytokine secretion was assayed by ELISA. The survival and carcinogenic abilities was detected by clone formation assay.

KEY FINDINGS

HO-1 expression in the BMSCs of stage III MM patients was substantially increased, compared with that of healthy donors and stage I/II patients. The results of co-culture of BMSCs and MM cells indicated that, the upregulated HO-1 inhibited the apoptosis of co-cultured MM cells, while downregulated HO-1 promoted the chemosensitivity of co-cultured MM cells, moreover, the upregulated HO-1 in BMSCs increased the colony-formation ability of MM cells. This protective capability may be regulated by CXCL12/CXCR4 signaling. High HO-1 expression in BMSCs can promote the phosphorylation of the JAK2/STAT3 pathway, thereby increasing secretion of SDF-1 in BMSCs and activating CXCL12/CXCR4 signaling. In addition, direct contact between BMSCs and MM cells may cause drug resistance.

SIGNIFICANCE

These results indicated that the regulation of HO-1 in BMSCs may be a new effective method of MM therapy.

[Expression and role of Pim1 in cultured cortical neurons with oxygen-glucose deprivation/reoxygen injury]

OBJECTIVE

To study the expression and effect of Pim1 in primary cortical neurons after hypoxic-ischemic injury.

METHODS

Cortical neurons were isolated from 1-day-old C57BL/6 mice and cultured in neurobasal medium. On the 8th day of neuron culture, cells were subjected to oxygen-glucose deprivation/reoxygen (OGD/R) treatment to mimic in vivo hypoxic injury of neurons. Briefly, medium were changed to DMEM medium, and cells were cultured in 1% O₂ for 3 hours and then changed back to normal medium and conditions. Cells were collected at 0 hour, 6 hours, 12 hours and 24 hours after OGD/R. Primary neurons were transfected with Pim1 overexpression plasmid or mock plasmid, and then were exposed to normal conditions or OGD/R treatment. They were named as Pim1 group, control group, OGD/R group and OGD/R+Pim1 group respectively. Real-time PCR was used to detect Pim1 mRNA expression. Western blot was used to detect the protein expression of Pim1 and apoptotic related protein cleaved caspase 3 (CC3). TUNEL staining was used to detect cell apoptosis.

RESULTS

Real-time PCR and Western blot results showed that Pim1 mRNA and protein were significantly decreased in neurons after OGD/R. They began to decrease at 0 hour after OGD/R, reached to the lowest at 12 hours after OGD/R, and remained at a lower level at 24 hours after OGD/R (P<0.01). Overexpression of Pim1 significantly upregulated the protein level of Pim1. Under OGD/R conditions, the CC3 expression and the apoptosis rate in cells of the Pim1 group were significantly lower than in un-transfected cells (P<0.01).

CONCLUSIONS

Hypoxic-ischemic injury may decrease Pim1 expression in neurons. Overexpressed Pim1 may inhibit apoptosis induced by OGD/R.

A STAT3 of Addiction: Adipose Tissue, Adipocytokine Signalling and STAT3 as Mediators of Metabolic Remodelling in the Tumour Microenvironment

Metabolic remodelling of the tumour microenvironment is a major mechanism by which cancer cells survive and resist treatment. The pro-oncogenic inflammatory cascade released by adipose tissue promotes oncogenic transformation, proliferation, angiogenesis, metastasis and evasion of apoptosis. STAT3 has emerged as an important mediator of metabolic remodelling. As a downstream effector of adipocytokines and cytokines, its canonical and non-canonical activities affect mitochondrial functioning and cancer metabolism. In this review, we examine the central role played by the crosstalk between the transcriptional and mitochondrial roles of STAT3 to promote survival and further oncogenesis within the tumour microenvironment with a particular focus on adipose-breast cancer interactions.

PIM1 inhibitor synergizes the anti-tumor effect of osimertinib via STAT3 dephosphorylation in EGFR-mutant non-small cell lung cancer

Background

An increasing amount of evidence has demonstrated that combined or multiple targeted therapies could bring about more durable clinical outcomes, and it is known that epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) resistance is related to bypass activation. This study aims to explore a specific solution for third-generation EGFR-TKI resistance caused by bypass activation, and to examine the antitumor effects of the combination of a novel inhibitor CX-6258 HCl with osimertinib, along with its underlining mechanisms.

Methods

A bioinformatics analysis was performed to detect the relations between the provirus integration site for Moloney murine leukemia virus 1 (PIM1) expression and prognosis of lung cancer. The EGFR-mutated lung cancer cell lines were treated with the combination of CX-6258 HCl and osimertinib to analyze cell proliferation using the Cell Counting Kit-8, colony formation, and in vivo experiments. Cell migration was analyzed using wound healing and Transwell assays. The apoptosis level was detected using Annexin V-propidium iodide flow cytometry. The expression levels of EGFR and STAT3 were determined using Western blot analysis.

Results

High expression level of PIM1 was related to the poor prognosis of non-small cell lung cancer (NSCLC). The combined administration of osimertinib and CX-6258 HCl significantly inhibited cell proliferation and migration and effectively induced apoptosis in lung cancer cells. It was more efficient in suppressing EGFR activation and phosphorylation of STAT3 compared with osimertinib treatment alone. Furthermore, it showed a durable efficacy in a xenograft model.

Conclusions

This study showed that PIM1 is a poor prognostic factor for NSCLC. CX-6258 HCl is a potential molecular inhibitor to sensitize the antitumor effects of osimertinib through the inhibiting of the phosphorylation of STAT3 in NSCLC.

PIM kinase inhibition: co-targeted therapeutic approaches in prostate cancer

PIM kinases have been shown to play a role in prostate cancer development and progression, as well as in some of the hallmarks of cancer, especially proliferation and apoptosis. Their upregulation in prostate cancer has been correlated with decreased patient overall survival and therapy resistance. Initial efforts to inhibit PIM with monotherapies have been hampered by compensatory upregulation of other pathways and drug toxicity, and as such, it has been suggested that co-targeting PIM with other treatment approaches may permit lower doses and be a more viable option in the clinic. Here, we present the rationale and basis for co-targeting PIM with inhibitors of PI3K/mTOR/AKT, JAK/STAT, MYC, stemness, and RNA Polymerase I transcription, along with other therapies, including androgen deprivation, radiotherapy, chemotherapy, and immunotherapy. Such combined approaches could potentially be used as neoadjuvant therapies, limiting the development of resistance to treatments or sensitizing cells to other therapeutics. To determine which drugs should be combined with PIM inhibitors for each patient, it will be key to develop companion diagnostics that predict response to each co-targeted option, hopefully providing a personalized medicine pathway for subsets of prostate cancer patients in the future.