Inhibition of JAK2 signaling by TG101209 enhances radiotherapy in lung cancer models

Replication stress response and radioresistance in lung cancer: Mechanistic insights and advanced therapeutic approaches

Lung cancer, the leading cause of cancer mortality globally, comprises mainly non-small cell lung cancer and small cell lung cancer. Its pathogenesis involves genetic mutations, environmental exposures, chronic inflammation, and tumor microenvironment interactions. Critical genes like TP53, RB1, KRAS, and EGFR often mutate, driving uncontrolled cell growth. Radiation therapy, a primary treatment, faces challenges with radioresistance due to DNA repair mechanisms and replication stress responses. Emerging therapeutic strategies target DNA repair pathways, cell cycle checkpoints, and immune responses to enhance radiosensitivity and counteract resistance. Promising approaches include PARP inhibitors, CDK inhibitors, EGFR blockers, and immunotherapies combined with radiation. Advances in understanding these mechanisms are crucial for developing targeted therapies to improve lung cancer patient outcomes. The present review focuses on elucidating the intricate mechanisms of lung cancer pathogenesis and radioresistance, while highlighting novel therapeutic strategies designed to overcome these challenges and improve treatment efficacy.

Study on the mechanism of hyperoside in affecting the biological progression and radiosensitivity of esophageal carcinoma by modulating the STAT3/AKT/ERK pathway

Hyperoside (HYP) exhibits diverse pharmacological effects and holds potential for enhancing chemotherapy sensitivity. However, few studies have reported the impact of HYP on the malignant progression of esophageal carcinoma (EC) and its sensitivity to radiotherapy. The impact of HYP on the viability of EC cells (TE-1 and KYSE-150) was assessed using Cell Counting Kit-8 (CCK-8) assays. The biological characteristics and radiosensitivity of EC cells following HYP treatment were evaluated through clone formation experiments, flow cytometry, scratch wound-healing assays, and transwell migration and invasion assays. Western blot analysis was performed to determine the levels of proteins associated with cell death and epithelial-mesenchymal transition (EMT), as well as to explore whether HYP interferes with the radiosensitivity of EC cells via the  STAT3/AKT/ERK pathways. Finally, a subcutaneous graft tumor model was constructed to investigate the effects of HYP and X-ray treatments on in vivo tumor growth. The findings indicated a dose-dependent decrease in the survival rate of KYSE-150 and TE-1 cells following HYP treatment. HYP treatment also inhibited cell proliferation, invasion, migration, and EMT, while increasing the apoptotic rate and radiosensitivity of the cells. Notably, HYP suppressed the malignant progression of EC and enhanced radiosensitivity via the STAT3/AKT/ERK pathway. Moreover, HYP impaired the growth of EC tumors in mice, with the combined HYP and X-ray treatment exerting a stronger inhibitory effect. In conclusion, HYP increases the radiosensitivity of esophageal carcinoma cells, offering considerable promise for application in the clinical treatment of EC.

Enhancement of radio-sensitivity by inhibition of Janus kinase signaling with oclacitinib in canine tumor cell lines

A combination of irradiation and oclacitinib, a Janus kinase (JAK) inhibitor used in dogs, could lead to synergistic anticancer effects in canine tumors. However, the anti-tumor effects of oclacitinib remain unclear. This study investigated the radio-sensitizing effect of oclacitinib in canine tumors and determined its underlying mechanisms using osteosarcoma (HMPOS), malignant melanoma (CMeC), and thyroid adenocarcinoma (CTAC) cell lines. A clonogenic assay and a tumor growth assessment in a xenograft mouse model (BALB/cAJcl-nu/nu) were performed to evaluate the radio-sensitizing effects of oclacitinib. Oclacitinib enhanced the radio-sensitivity of tumor cells both in vitro and in vivo. The signal transducer and activator of transcription (STAT)3 expression was activated and suppressed by oclacitinib in X-irradiation-exposed cells. Oclacitinib enhanced radiation-induced apoptosis only in HMPOS cells by inhibiting anti-apoptotic genes. In addition, oclacitinib inhibited the transcription of cell-cycle-regulating genes and arrested cell cycle progression from the G1 phase to subsequent phases. In conclusion, oclacitinib enhanced radio-sensitivity both in vitro and in vivo by triggering apoptosis and impeding cell cycle progression via STAT3 inhibition in canine tumor cell lines. This study suggested the clinical therapeutic potential of oclacitinib and radiation therapy in enhancing treatment efficacy and outcomes in canine tumors.

Aberrantly Expressed Mitochondrial Lipid Kinase, AGK, Activates JAK2-Histone H3 Axis and BCR Signal: A Mechanistic Study with Implication in CLL Therapy

PURPOSE

Although the B-cell receptor (BCR) signal plays a critical role in chronic lymphocytic leukemia (CLL) cell survival and a target of current therapies (ibrutinib targets Bruton's tyrosine kinase; idelalisib targets PI3Kδ), contribution of the cytokine-driven JAK2 pathway to the "CLL cell-survival signaling network" is largely undefined.

EXPERIMENTAL DESIGN

Patients with CLL were enrolled to investigate expression/activation of JAK2 and acylglycerol kinase (AGK), and their functional implication in primary CLL cell survival. A series of biochemical and molecular biology assays were employed to uncover the underlying mechanism.

RESULTS

We detected that compared with normal B cells, CLL cells aberrantly express constitutively active JAK2. Mechanistically, HSP90 forms a chaperoning complex with JAK2, resulting in its aberrant accumulation in CLL cells. We also discovered aberrant upregulation of a novel mitochondrial lipid kinase, AGK, which remains complexed with HSP90 in CLL cells activating JAK2. Although AGK is typically mitochondrial, we detected its nuclear localization in association with JAK2 in some CLL cells. Functionally, JAK2 phosphorylates its noncanonical substrate, histone H3(Y41), but not STAT3, activating transcription of diverse sets of genes in a patient-specific manner. Additionally, JAK2 activates the BCR signal in CLL cells via LYN/Bruton's tyrosine kinase axis. Targeted inhibition of JAK2 as monotherapy, or in combination with the BCR inhibitors or venetoclax (a BCL2 inhibitor), induced apoptosis synergistically in CLL cells.

CONCLUSIONS

These findings suggest that aberrantly expressed AGK activates JAK2, independent of cytokine, leading to activation of diverse sets of gene transcription in CLL cells. Combined targeting of JAK2 and BCR signals or BCL2 may be effective in some patients with CLL.

Network pharmacology and molecular docking reveal the mechanism of action of Bergapten against non‑small cell lung cancer

Non-small cell lung cancer (NSCLC) is a leading cause of cancer mortality worldwide, necessitating new treatment approaches with minimal side effects. In the present study, the potential of Bergapten (5-methoxypsoralen), a natural furanocoumarin compound, as a therapeutic agent against NSCLC was investigated by using network pharmacology, molecular docking and in vitro validation. Bergapten targets were identified using the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform and SwissTarget databases, whilst lung cancer-related targets were sourced from GeneCards and DisGeNET. Protein-protein interaction analysis and molecular docking were performed to identify key targets. The inhibitory effects of Bergapten on lung cancer cells were assessed using Cell Counting Kit-8 assays, wound healing assays, cell migration experiments, flow cytometry and western blotting. SC79 was used to verify the regulation of Bergapten on the PI3K/AKT pathway. Network pharmacology identified 51 targets, one signaling pathway and four Gene Ontology projects associated with the action of Bergapten against NSCLC. Key targets identified included glycogen synthase kinase-3β, Janus kinase 2, phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit α and protein tyrosine kinase 2. In vitro experiments demonstrated that Bergapten significantly inhibited cell viability, promoted apoptosis, induced cellular senescence and inhibited the PI3K/AKT signaling pathway in NSCLC cells. In conclusion, Bergapten exerts its anti-NSCLC effects through the PI3K/AKT pathway, promoting cell senescence and inhibiting inflammation. These findings suggest that Bergapten has potential as a therapeutic agent for NSCLC.

Survivin (BIRC5): Implications in cancer therapy

Inhibitors of Apoptosis proteins (IAPs) were discovered through experiments aimed at rescuing apoptosis in insects. Classically associated with the inhibition of apoptosis, the IAP member Survivin also regulates cell cycle progression and is an essential component of the Chromosomal Passenger Complex (CPC), responsible for chromosomal segregation. Although undetectable in most adult tissues, Survivin is expressed in Adult Stem Cells (ASCs) and plays a crucial role in their maintenance. Survivin is overexpressed in most cancers, contributing to their clonal expansion. As a result, it has been proposed as a possible anticancer target for nearly two decades. In this discussion, we will explore the rationale behind Survivin as a therapeutic target, focusing on common cancer types such as carcinomas, sarcomas, and leukemias. We will delve into the modulation of Survivin by cancer pro-survival cell signaling, the association between SNPs and tumorigenesis, and its regulation by miRNAs. Finally, we will compare cell growth, clonogenic capacity, and apoptosis, along with different strategies for Survivin inhibition, including gene expression and protein activity modulation.

Serine/Threonine kinase 16 phosphorylates STAT3 and confers a JAK2-Inhibition resistance phenotype in triple-negative breast cancer

Although Janus kinase 2 (JAK2) plays a critical role in the progression of triple-negative breast cancer (TNBC), its inhibitors are incapable of eradicating these tumor cells, implicating drug resistance mechanisms exist. Our evidences show that TNBC cells express high level of Serine/Threonine Kinase 16 (STK16) when JAK2 signaling is blocked. Pharmacological inhibition or silencing of STK16 significantly enhances the sensitivity of TNBC cells to JAK2 inhibition, while over-expression of STK16 alleviates the anti-tumor effect of JAK2-inhibitor. Mechanistically, elevated STK16 expression rescues the phosphorylation status and transcriptional activity of STAT3, as STK16 is able to directly catalyze the phosphorylation of STAT3 at ser-727 residue. Our data indicate that upon JAK2 inhibition, TNBC cells express STK16 to maintain STAT3 transcriptional activity, dual-inhibition of JAK2/STK16 offers a potential way to treat TNBC patients.

Interleukin-6 serves as a critical factor in various cancer progression and therapy

Interleukin-6 (IL-6), a pro-inflammatory cytokine, plays a crucial role in host immune defense and acute stress responses. Moreover, it modulates various cellular processes, including proliferation, apoptosis, angiogenesis, and differentiation. These effects are facilitated by various signaling pathways, particularly the signal transducer and activator of transcription 3 (STAT3) and Janus kinase 2 (JAK2). However, excessive IL-6 production and dysregulated signaling are associated with various cancers, promoting tumorigenesis by influencing all cancer hallmarks, such as apoptosis, survival, proliferation, angiogenesis, invasiveness, metastasis, and notably, metabolism. Emerging evidence indicates that selective inhibition of the IL-6 signaling pathway yields therapeutic benefits across diverse malignancies, such as multiple myeloma, prostate, colorectal, renal, ovarian, and lung cancers. Targeting key components of IL-6 signaling, such as IL-6Rs, gp130, STAT3, and JAK via monoclonal antibodies (mAbs) or small molecules, is a heavily researched approach in preclinical cancer studies. The purpose of this study is to offer an overview of the role of IL-6 and its signaling pathway in various cancer types. Furthermore, we discussed current preclinical and clinical studies focusing on targeting IL-6 signaling as a therapeutic strategy for various types of cancer.

Review: Mechanisms and perspective treatment of radioresistance in non-small cell lung cancer

Radiotherapy is the major treatment of non-small cell lung cancer (NSCLC). The radioresistance and toxicity are the main obstacles that leading to therapeutic failure and poor prognosis. Oncogenic mutation, cancer stem cells (CSCs), tumor hypoxia, DNA damage repair, epithelial-mesenchymal transition (EMT), and tumor microenvironment (TME) may dominate the occurrence of radioresistance at different stages of radiotherapy. Chemotherapy drugs, targeted drugs, and immune checkpoint inhibitors are combined with radiotherapy to treat NSCLC to improve the efficacy. This article reviews the potential mechanism of radioresistance in NSCLC, and discusses the current drug research to overcome radioresistance and the advantages of Traditional Chinese medicine (TCM) in improving the efficacy and reducing the toxicity of radiotherapy.

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.

Selective suppression of melanoma lacking IFN-γ pathway by JAK inhibition depends on T cells and host TNF signaling

Therapeutic resistance to immune checkpoint blockers (ICBs) in melanoma patients is a pressing issue, of which tumor loss of IFN-γ signaling genes is a major underlying mechanism. However, strategies of overcoming this resistance mechanism have been largely elusive. Moreover, given the indispensable role of tumor-infiltrating T cells (TILs) in ICBs, little is known about how tumor-intrinsic loss of IFN-γ signaling (IFNγR1KO) impacts TILs. Here, we report that IFNγR1KO melanomas have reduced infiltration and function of TILs. IFNγR1KO melanomas harbor a network of constitutively active protein tyrosine kinases centered on activated JAK1/2. Mechanistically, JAK1/2 activation is mediated by augmented mTOR. Importantly, JAK1/2 inhibition with Ruxolitinib selectively suppresses the growth of IFNγR1KO but not scrambled control melanomas, depending on T cells and host TNF. Together, our results reveal an important role of tumor-intrinsic IFN-γ signaling in shaping TILs and manifest a targeted therapy to bypass ICB resistance of melanomas defective of IFN-γ signaling.

Discovery, Significance, and Utility of JAK2 Mutation in Squamous Cell Carcinoma of the Lung

Lung cancer continues to be the leading cause of cancer-related deaths worldwide. Many studies show lung cancer is a histologically and molecularly heterogeneous group, even within the same histological subtype. Liquid biopsies are a new tool that can identify targetable genomic mutations and impact management. JAK2 p.V617F is a mutation commonly found in myeloproliferative neoplasms but rarely identified in non-small cell lung cancer (NSCLCs). The significance of Janus Kinase (JAK2) mutation in lung cancer is not clearly understood. However, it is thought that it may have a role in treating solid tumors, such as lung cancer. We present two cases of patients diagnosed with NSCLC who were discovered to have JAK2 V617F mutation on liquid biopsy.

Glycosylation of Methylflavonoids in the Cultures of Entomopathogenic Filamentous Fungi as a Tool for Obtaining New Biologically Active Compounds

Flavonoid compounds are secondary plant metabolites with numerous biological activities; they naturally occur mainly in the form of glycosides. The glucosyl moiety attached to the flavonoid core makes them more stable and water-soluble. The methyl derivatives of flavonoids also show increased stability and intestinal absorption. Our study showed that such flavonoids can be obtained by combined chemical and biotechnological methods with entomopathogenic filamentous fungi as glycosylation biocatalysts. In the current paper, two flavonoids, i.e., 2′-hydroxy-4-methylchalcone and 4′-methylflavone, have been synthesized and biotransformed in the cultures of two strains of entomopathogenic filamentous fungi Isaria fumosorosea KCH J2 and Beauveria bassiana KCH J1.5. Biotransformation of 2′-hydroxy-4-methylchalcone resulted in the formation of two dihydrochalcone glucopyranoside derivatives in the culture of I. fumosorosea KCH J2 and chalcone glucopyranoside derivative in the case of B. bassiana KCH J1.5. 4′-Methylflavone was transformed in the culture of I. fumosorosea KCH J2 into four products, i.e., 4′-hydroxymethylflavone, flavone 4′-methylene-O-β-d-(4″-O-methyl)-glucopyranoside, flavone 4′-carboxylic acid, and 4′-methylflavone 3-O-β-d-(4″-O-methyl)-glucopyranoside. 4′-Methylflavone was not efficiently biotransformed in the culture of B. bassiana KCH J1.5. The computer-aided simulations based on the chemical structures of the obtained compounds showed their improved physicochemical properties and antimicrobial, anticarcinogenic, hepatoprotective, and cardioprotective potential.

Molecular Radiobiology in Non-Small Cell Lung Cancer: Prognostic and Predictive Response Factors

Simple Summary

The identification of prognostic and predictive gene signatures of response to cancer treatment (radiotherapy) could help in making therapeutic decisions in patients affected by NSCLC. There are multiple proposals for gene signatures that attempt to predict survival or predict response to treatment (not radiotherapy), but they mainly focus on early stages or metastasis at diagnosis. In contrast, there have been few studies that raise these predictive and/or prognostic elements in nonmetastatic locally advanced stages, where treatment with ionizing radiation plays an important role. In this work, we review in depth previous works discovering the prognostic and predictive response factors in non-small cell lung cancer, specially focused on non-deeply studied radiation-based therapy.

Abstract

Non-small-cell lung cancer (NSCLC) is the leading cause of cancer-related death worldwide, generating huge economic and social impacts that have not slowed in recent years. Oncological treatment for this neoplasm usually includes surgery, chemotherapy, treatments on molecular targets and ionizing radiation. The prognosis in terms of overall survival (OS) and the different therapeutic responses between patients can be explained, to a large extent, by the existence of widely heterogeneous molecular profiles. The identification of prognostic and predictive gene signatures of response to cancer treatment, could help in making therapeutic decisions in patients affected by NSCLC. Given the published scientific evidence, we believe that the search for prognostic and/or predictive gene signatures of response to radiotherapy treatment can significantly help clinical decision-making. These signatures may condition the fractions, the total dose to be administered and/or the combination of systemic treatments in conjunction with radiation. The ultimate goal is to achieve better clinical results, minimizing the adverse effects associated with current cancer therapies.

Prediction of drug candidates for clear cell renal cell carcinoma using a systems biology-based drug repositioning approach

BACKGROUND

The response rates of the clinical chemotherapies are still low in clear cell renal cell carcinoma (ccRCC). Computational drug repositioning is a promising strategy to discover new uses for existing drugs to treat patients who cannot get benefits from clinical drugs.

METHODS

We proposed a systematic approach which included the target prediction based on the co-expression network analysis of transcriptomics profiles of ccRCC patients and drug repositioning for cancer treatment based on the analysis of shRNA- and drug-perturbed signature profiles of human kidney cell line.

FINDINGS

First, based on the gene co-expression network analysis, we identified two types of gene modules in ccRCC, which significantly enriched with unfavorable and favorable signatures indicating poor and good survival outcomes of patients, respectively. Then, we selected four genes, BUB1B, RRM2, ASF1B and CCNB2, as the potential drug targets based on the topology analysis of modules. Further, we repurposed three most effective drugs for each target by applying the proposed drug repositioning approach. Finally, we evaluated the effects of repurposed drugs using an in vitro model and observed that these drugs inhibited the protein levels of their corresponding target genes and cell viability.

INTERPRETATION

These findings proved the usefulness and efficiency of our approach to improve the drug repositioning researches for cancer treatment and precision medicine.

FUNDING

This study was funded by Knut and Alice Wallenberg Foundation and Bash Biotech Inc., San Diego, CA, USA.

The Diverse Analysis Identifies Mutated KRAS Associated With Radioresistance in Non-Small Cell Lung Cancer

Background

To analyze the relationship between V-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) status and radioresistance in non-small cell lung cancer (NSCLC), we identified potential genotypic differences and pathways involved.

Methods

We retrospectively analyzed epidermal growth factor receptor (EGFR) and KRAS status in patients undergoing definitive radiotherapy for NSCLC between 2004 and 2018. Cox proportional hazard models were used to evaluate local progression-free survival (LPFS). Using clonogenic survival and measurement of γH2AX foci, we analyzed the difference in radiosensitivity between NSCLC cell lines with different KRAS status. The Cancer Genome Atlas (TCGA) analysis was used to explore the potential pathways involved.

Results

The results showed that of the 286 patients identified, 68 (24%) had local tumor progression (mean ± standard deviation (SD), 27 ± 17.4 months); of these patients, KRAS mutations were found in 14 (23%), and KRAS status was associated with LPFS. After adjusting for concurrent chemotherapy, gross tumor volume, and mutation status in multivariate analysis, KRAS mutation was associated with shorter LPFS (hazard ratio: 1.961; 95% confidence interval: 1.03 - 2.17; P = 0.032). KRAS mutation showed higher radioresistance in vitro. TCGA data showed that the ERK1/2 pathway, phosphatidylinositol I3 kinase (PI3K)/mTOR, p38 MAPK pathway, cell cycle checkpoint signaling, DNA damage, repair pathways, and EGFR/PKC/AKT pathway were differentially expressed in patients with KRAS mutations or cell lines compared with their expression in the wild-type group.

Conclusions

Diverse analyses identified that KRAS mutation was associated with radioresistance in NSCLC. KRAS mutation status may be helpful as a biomarker of radioresistance and a potential target to increase radiosensitivity.

The role of the STAT3 signaling transduction pathways in radioresistance

The efficacy of radiotherapy has long known to be limited by the emergence of resistance. The four Rs of radiotherapy (DNA damage repair, reoxygenation, redistribution of the cell cycle, and repopulation) are generally accepted concepts in radiobioolgy. Recent studies have strongly linked signal transducer and activator of transcription 3 (STAT3) to the regulation of cancer stemness and radioresistance. In particular, a STAT3 pathway inhibitor napabucasin, claimed to be the first cancer stemness antagonist in clinical trials, strengthens the link. However, no reviews connect STAT3 with the four Rs of radiotherapy. Herein, the evidence-based role of STAT3 in radioresistance is discussed in relation to the four Rs of radiotherapy. The proposed mechanisms include upstream and downstream effector proteins of STAT3, including FOXM1, MELK, NEK2, AKT, EZH2, and HIF1α. Downstream transcriptional products of the mechanistically-related proteins are involved in cancer stemness, anti-apoptosis, and the four Rs of radiotherapy. Utilizing selective inhibitors of the mechanistically-related proteins has shown promising antagonism of radioresistance, suggesting that the expression levels of these proteins may be biomarkers for the prediction of radiotherapeutic outcomes, and that this molecular mechanism may provide a rational axis through which to treat radioresistance.

Second-Generation Jak2 Inhibitors for Advanced Prostate Cancer: Are We Ready for Clinical Development?

Simple Summary

Prostate Cancer (PC) is currently estimated to affect 1 in 9 men and is the second leading cause of cancer in men in the US. While androgen deprivation therapy, which targets the androgen receptor, is one of the front-line therapies for advanced PC and for recurrence of organ-confined PC treated with surgery, lethal castrate-resistant PC develops consistently in patients. PC is a multi-focal cancer with different grade carcinoma areas presenting simultaneously. Jak2-Stat5 signaling pathway has emerged as a potentially highly effective molecular target in PCs with positive areas for activated Stat5 protein. Activated Jak2-Stat5 signaling can be readily targeted by the second-generation Jak2-inhibitors that have been developed for myeloproliferative and autoimmune disorders and hematological malignancies. In this review, we analyze and summarize the Jak2 inhibitors that are currently in preclinical and clinical development.

Abstract

Androgen deprivation therapy (ADT) for metastatic and high-risk prostate cancer (PC) inhibits growth pathways driven by the androgen receptor (AR). Over time, ADT leads to the emergence of lethal castrate-resistant PC (CRPC), which is consistently caused by an acquired ability of tumors to re-activate AR. This has led to the development of second-generation anti-androgens that more effectively antagonize AR, such as enzalutamide (ENZ). However, the resistance of CRPC to ENZ develops rapidly. Studies utilizing preclinical models of PC have established that inhibition of the Jak2-Stat5 signaling leads to extensive PC cell apoptosis and decreased tumor growth. In large clinical cohorts, Jak2-Stat5 activity predicts PC progression and recurrence. Recently, Jak2-Stat5 signaling was demonstrated to induce ENZ-resistant PC growth in preclinical PC models, further emphasizing the importance of Jak2-Stat5 for therapeutic targeting for advanced PC. The discovery of the Jak2V617F somatic mutation in myeloproliferative disorders triggered the rapid development of Jak1/2-specific inhibitors for a variety of myeloproliferative and auto-immune disorders as well as hematological malignancies. Here, we review Jak2 inhibitors targeting the mutated Jak2V617F vs. wild type (WT)-Jak2 that are currently in the development pipeline. Among these 35 compounds with documented Jak2 inhibitory activity, those with potency against WT-Jak2 hold strong potential for advanced PC therapy.

The JAK2 inhibitor TG101209 exhibits anti-tumor and chemotherapeutic sensitizing effects on Burkitt lymphoma cells by inhibiting the JAK2/STAT3/c-MYB signaling axis

Constitutive activation of JAK2/STAT3 is a major oncogenic signaling event involved in the development of Burkitt lymphoma (BL). In the present study, we investigated the antilymphoma activity of TG101209, a specific JAK2 inhibitor, on EBV-positive and EBV-negative Burkitt lymphoma cell lines and primary BL cells. The results showed that TG101209 had a significant antilymphoma effect by inhibiting BL cell growth and inducing apoptosis along with cell differentiation toward mature B cells in vitro. We also found that TG101209 displayed significant synergistic action and a sensitizing effect on the anti-Burkitt lymphoma activity of doxorubicin. In vivo experiments indicated that TG101209 could suppress tumor growth and prolong the overall survival of BL cell-bearing mice. The mechanistic study indicated that TG101209, by suppressing the JAK2/STAT3/c-MYB signaling axis and crosstalk between the downstream signaling pathways, plays an antilymphoma role. These data suggested that TG101209 may be a promising agent or alternative choice for the treatment of BL.

SWIM domain protein ZSWIM4 is required for JAK2 inhibition resistance in breast cancer

AIMS

Janus kinase 2 (JAK2)/signal transducer and activator of transcription (STAT) signaling plays a critical role in the progression of breast cancer. However, a small part of tumor cells survived from the killing effect of JAK2 inhibitor. We aimed to find out the mechanism of drug resistance in breast cancer cells and develop new therapeutic strategies.

MATERIALS AND METHODS

The anti-tumor effect of TG101209 in breast cancer cells was confirmed by cell counting kit 8 and flow cytometry. Western blotting was used to determine the up-regulation of zinc finger SWIM-type containing 4 (ZSWIM4) induced by TG101209. In vitro and in vivo experiments were performed to evaluate the role of ZSWIM4 in the resistance of breast cancer cells to TG101209. Through the determination and analysis of 50% inhibiting concentration (IC₅₀) curves, the effect of combination therapy was confirmed.

KEY FINDINGS

Our data indicate that the elevated expression of ZSWIM4 contributes to JAK2 inhibition resistance, as knockdown of ZSWIM4 significantly enhances the sensitivity of breast cancer cells to TG101209 and over-expression of this gene mitigates the killing effect. Furthermore, the expression of vitamin D receptor (VDR) and utilization of 1α,25-(OH)2VD3 is decreased in ZSWIM4-knockdown breast cancer cells. VDR-silencing or GW0742-mediated blockade of VDR activity can partially reverse the JAK2 inhibition resistance.

SIGNIFICANCE

Our data implicated that ZSWIM4 might be an inducible resistance gene of JAK2 inhibition in breast cancer cells. The combination of JAK2 inhibitor and VDR inhibitor may achieve better coordinated therapeutic effect in breast cancer.

Emerging Importance of Survivin in Stem Cells and Cancer: the Development of New Cancer Therapeutics

Survivin is one of the rare proteins that is differentially expressed in normal and cancer cells and is directly or indirectly involved in numerous pathways required for tumor maintenance. It is expressed in almost all cancers and its expression has been detected at early stages of cancer. These traits make survivin an exceptionally attractive target for cancer therapeutics. Even with these promising features to be an oncotherapeutic target, there has been limited success in the clinical trials targeting survivin. Only recently it has emerged that survivin was not being specifically targeted which could have resulted in the negative clinical outcome. Also, focus of research has now shifted from survivin expression in the overall heterogeneous tumor cell populations to survivin expression in cancer stem cells as these cells have proved to be the major drivers of tumors. Therefore, in this review we have analyzed the expression of survivin in normal and cancer cells with a particular focus on its expression in cancer stem cell compartment. We have discussed the major signaling pathways involved in regulation of survivin. We have explored the current development status of various types of interventions for inhibition of survivin. Furthermore, we have discussed the challenges involving the development of potent and specific survivin inhibitors for cancer therapeutics. Finally we have given insights for some of the promising future anticancer treatments.

Potential Molecular Targets in the Setting of Chemoradiation for Esophageal Malignancies

Although the development of effective combined chemoradiation regimens for esophageal cancers has resulted in statistically significant survival benefits, the majority of patients treated with curative intent develop locoregional and/or distant relapse. Further improvements in disease control and survival will require the development of individualized therapy based on the knowledge of host and tumor genomics and potentially harnessing the host immune system. Although there are a number of gene targets that are amplified and proteins that are overexpressed in esophageal cancers, attempts to target several of these have not proven successful in unselected patients. Herein, we review our current state of knowledge regarding the molecular pathways implicated in esophageal carcinoma, and the available agents for targeting these pathways that may rationally be combined with standard chemoradiation, with the hope that this commentary will guide future efforts of novel combinations of therapy.

Radiotherapy, immunotherapy, and the tumour microenvironment: Turning an immunosuppressive milieu into a therapeutic opportunity

Immune checkpoint blockade (ICB) has revolutionised the treatment of solid tumours, yet most patients do not derive a clinical benefit. Resistance to ICB is often contingent on the tumour microenvironment (TME) and modulating aspects of this immunosuppressive milieu is a goal of combination treatment approaches. Radiation has been used for over a century in the management of cancer with more than half of all cancer patients receiving radiotherapy. Here, we outline the rationale behind combining radiotherapy with ICB, a potential synergy through mutually beneficial remodelling of the TME. We discuss the pleiotropic effects radiation has on the TME including immunogenic cell death, activation of cytosolic DNA sensors, remodelling the stroma and vasculature, and paradoxical infiltration of both anti-tumour and suppressive immune cell populations. These events depend on the radiation dose and fractionation and optimising these parameters will be key to develop safe and effective combination regimens. Finally, we highlight ongoing efforts that combine radiation, immunotherapy and inhibitors of DNA damage response, which can help achieve a favourable equilibrium between the immunogenic and tolerogenic effects of radiation on the immune microenvironment.

STAT3, the Challenge for Chemotherapeutic and Radiotherapeutic Efficacy

Chemoradiotherapy is one of the most effective and extensively used strategies for cancer treatment. Signal transducer and activator of transcription 3 (STAT3) regulates vital biological processes, such as cell proliferation and cell growth. It is constitutively activated in various cancers and limits the application of chemoradiotherapy. Accumulating evidence suggests that STAT3 regulates resistance to chemotherapy and radiotherapy and thereby impairs therapeutic efficacy by mediating its feedback loop and several target genes. The alternative splicing product STAT3β is often identified as a dominant-negative regulator, but it enhances sensitivity to chemotherapy and offers a new and challenging approach to reverse therapeutic resistance. We focus here on exploring the role of STAT3 in resistance to receptor tyrosine kinase (RTK) inhibitors and radiotherapy, outlining the potential of targeting STAT3 to overcome chemo(radio)resistance for improving clinical outcomes, and evaluating the importance of STAT3β as a potential therapeutic approach to overcomes chemo(radio)resistance. In this review, we discuss some new insights into the effect of STAT3 and its subtype STAT3β on chemoradiotherapy sensitivity, and we explore how these insights influence clinical treatment and drug development for cancer.

NVP-BSK805, an Inhibitor of JAK2 Kinase, Significantly Enhances the Radiosensitivity of Esophageal Squamous Cell Carcinoma in vitro and in vivo

Purpose

Radiotherapy is one major curative treatment modality for esophageal squamous cell carcinoma (ESCC) patients. This study aimed to find out small-molecular kinase inhibitors, which can significantly enhance the radiosensitivity of ESCC in vitro and in vivo.

Materials and Methods

Ninety-three kinase inhibitors were tested for their radiosensitizing effect in ESCC cells through high-content screening. The radiosensitizing effect of kinase inhibitors was investigated in vitro by detection of DNA double-strand breaks (DSBs) and clonogenic survival assay. By the establishment of xenograft tumor models in BALB/c nude mice, the radiosensitizing effect of kinase inhibitors was investigated in vivo.

Results

Among the 93 kinase inhibitors tested, we found NVP-BSK805, an inhibitor of JAK2 kinase, significantly radiosensitized ESCC cells through enhancing DSBs, inhibiting DNA damage repair and arresting cell cycle in G2/M or G0/G1 phase. After treatment with NVP-BSK805, ESCC cells showed decreased clonogenic survival and delayed tumor growth in vivo. JAK2 kinase was highly expressed in tumor tissues of ESCC patients, while rarely expressed in matched normal esophageal epithelial tissues. Survival analysis revealed JAK2 kinase as a prognostic factor of ESCC patients treated with chemoradiotherapy.

Conclusion

Our study discovered JAK2 kinase as an attractive target to enhance the radiosensitivity of ESCC cells in vitro and in vivo.

Inhibition of Aurora A enhances radiosensitivity in selected lung cancer cell lines

Background

In mammalian cells, Aurora serine/threonine kinases (Aurora A, B, and C) are expressed in a cell cycle-dependent fashion as key mitotic regulators required for the maintenance of chromosomal stability. Aurora-A (AURKA) has been proven to be an oncogene in a variety of cancers; however, whether its expression relates to patient survival and the association with radiotherapy remains unclear in non-small cell lung cancer (NSCLC).

Methods

Here, we first analyzed AURKA expression in 63 NSCLC tumor samples by immunohistochemistry (IHC) and used an MTS assay to compare cell survival by targeting AURKA with MLN8237 (Alisertib) in H460 and HCC2429 (P53-competent), and H1299 (P53-deficient) cell lines. The radiosensitivity of MLN8237 was further evaluated by clonogenic assay. Finally, we examined the effect of combining radiation and AURKA inhibition in vivo with a xenograft model and explored the potential mechanism.

Results

We found that increased AURKA expression correlated with decreased time to progression and overall survival (p = 0.0447 and 0.0096, respectively). AURKA inhibition using 100 nM MLN8237 for 48 h decreases cell growth in a partially P53-dependent manner, and the survival rates of H460, HCC2429, and H1299 cells were 56, 50, and 77%, respectively. In addition, the survival of H1299 cells decreased 27% after ectopic restoration of P53 expression, and the radiotherapy enhancement was also influenced by P53 expression (DER H460 = 1.33; HCC2429 = 1.35; H1299 = 1.02). Furthermore, tumor growth of H460 was delayed significantly in a subcutaneous mouse model exposed to both MLN8237 and radiation.

Conclusions

Taken together, our results confirmed that the expression of AURKA correlated with decreased NSCLC patient survival, and it might be a promising inhibition target when combined with radiotherapy, especially for P53-competent lung cancer cells. Modulation of P53 function could provide a new option for reversing cell resistance to the AURKA inhibitor MLN8237, which deserves further investigation.

Cullin Ring Ubiquitin Ligases (CRLs) in Cancer: Responses to Ionizing Radiation (IR) Treatment

Treatment with ionizing radiation (IR) remains the cornerstone of therapy for multiple cancer types, including disseminated and aggressive diseases in the palliative setting. Radiotherapy efficacy could be improved in combination with drugs that regulate the ubiquitin-proteasome system (UPS), many of which are currently being tested in clinical trials. The UPS operates through the covalent attachment of ATP-activated ubiquitin molecules onto substrates following the transfer of ubiquitin from an E1, to an E2, and then to the substrate via an E3 enzyme. The specificity of ubiquitin ligation is dictated by E3 ligases, which select substrates to be ubiquitylated. Among the E3s, cullin ring ubiquitin ligases (CRLs) represent prototypical multi-subunit E3s, which use the cullin subunit as a central assembling scaffold. CRLs have crucial roles in controlling the cell cycle, hypoxia signaling, reactive oxygen species clearance and DNA repair; pivotal factors regulating the cancer and normal tissue response to IR. Here, we summarize the findings on the involvement of CRLs in the response of cancer cells to IR, and we discuss the therapeutic approaches to target the CRLs which could be exploited in the clinic.

The JAK2/STAT3/CCND2 Axis promotes colorectal Cancer stem cell persistence and radioresistance

Background

Radiotherapy (RT) is a highly effective multimodal nonsurgical treatment that is essential for patients with advanced colorectal cancer (CRC). Nevertheless, cell subpopulations displaying intrinsic radioresistance survive after RT. The reactivation of their proliferation and successful colonization at local or distant sites may increase the risk of poor clinical outcomes. Recently, radioresistant cancer cells surviving RT were reported to exhibit a more aggressive phenotype than parental cells, although the underlying mechanisms remain unclear.

Methods

By investigating public databases containing CRC patient data, we explored potential radioresistance-associated signaling pathways. Then, their mechanistic roles in radioresistance were investigated through multiple validation steps using patient-derived primary CRC cells, human CRC cell lines, and CRC xenografts.

Results

Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling was activated in radioresistant CRC tissues in correlation with local and distant metastases. JAK2 was preferentially overexpressed in the CRC stem cell subpopulation, which was accompanied by the phosphorylation of STAT proteins, especially STAT3. JAK2/STAT3 signaling played an essential role in promoting tumor initiation and radioresistance by limiting apoptosis and enhancing clonogenic potential. Mechanistically, the direct binding of STAT3 to the cyclin D2 (CCND2) promoter increased CCND2 transcription. CCND2 expression was required for persistent cancer stem cell (CSC) growth via the maintenance of an intact cell cycle and proliferation with low levels of DNA damage accumulation.

Conclusion

Herein, we first identified JAK2/STAT3/CCND2 signaling as a resistance mechanism for the persistent growth of CSCs after RT, suggesting potential biomarkers and regimens for improving outcomes among CRC patients.

Identification of Withaferin A as a Potential Candidate for Anti-Cancer Therapy in Non-Small Cell Lung Cancer

Low response rate and recurrence are common issues in lung cancer; thus, identifying a potential compound for these patients is essential. Utilizing an in silico screening method, we identified withaferin A (WA), a cell-permeable steroidal lactone initially extracted from Withania somnifera, as a potential anti-lung cancer and anti-lung cancer stem-like cell (CSC) agent. First, we demonstrated that WA exhibited potent cytotoxicity in several lung cancer cells, as evidenced by low IC₅₀ values. WA concurrently induced autophagy and apoptosis and the activation of reactive oxygen species (ROS), which plays an upstream role in mediating WA-elicited effects. The increase in p62 indicated that WA may modulate the autophagy flux followed by apoptosis. In vivo research also demonstrated the anti-tumor effect of WA treatment. We subsequently demonstrated that WA could inhibit the growth of lung CSCs, decrease side population cells, and inhibit lung cancer spheroid-forming capacity, at least through downregulation of mTOR/STAT3 signaling. Furthermore, the combination of WA and chemotherapeutic drugs, including cisplatin and pemetrexed, exerted synergistic effects on the inhibition of epidermal growth factor receptor (EGFR) wild-type lung cancer cell viability. In addition, WA can further enhance the cytotoxic effect of cisplatin in lung CSCs. Therefore, WA alone or in combination with standard chemotherapy is a potential treatment option for EGFR wild-type lung cancer and may decrease the occurrence of cisplatin resistance by inhibiting lung CSCs.

Osimertinib (AZD9291) increases radio‑sensitivity in EGFR T790M non‑small cell lung cancer

Osimertinib (AZD9291) is a third generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor that has demonstrated significant clinical benefits in patients with EGFR‑sensitizing mutations or the T790M mutation. However, the potential therapeutic effect of osimertinib combined with ionizing irradiation (IR) is not well understood. The present study investigated treatment with osimertinib combined with IR in EGFR T790M non‑small cell lung cancer (NCI‑H1975) in vitro and in vivo. The results revealed that osimertinib inhibited proliferation and clonogenic survival following irradiation, decreased G2/M phase arrest in irradiated cells, and delayed DNA damage repair in a concentration‑ and time‑dependent manner. Furthermore, osimertinib alone or in combination with IR, blocked the phosphorylation of EGFR (Tyr1068/Tyr1173), protein kinase B and extracellular signal‑regulated kinase. Osimertinib also enhanced the antitumor activity of IR in tumor‑bearing nude mice. The results of the present study indicated that osimertinib has therapeutic potential as a radiation‑sensitizer in lung cancer cells harboring the EGFR T790M mutation, providing a rationale for clinically combining osimertinib with irradiation in EGFR T790M non‑small cell lung cancer.

"Do We Know Jack" About JAK? A Closer Look at JAK/STAT Signaling Pathway

Janus tyrosine kinase (JAK) family of proteins have been identified as crucial proteins in signal transduction initiated by a wide range of membrane receptors. Among the proteins in this family JAK2 has been associated with important downstream proteins, including signal transducers and activators of transcription (STATs), which in turn regulate the expression of a variety of proteins involved in induction or prevention of apoptosis. Therefore, the JAK/STAT signaling axis plays a major role in the proliferation and survival of different cancer cells, and may even be involved in resistance mechanisms against molecularly targeted drugs. Despite extensive research focused on the protein structure and mechanisms of activation of JAKs, and signal transduction through these proteins, their importance in cancer initiation and progression seem to be underestimated. This manuscript is an attempt to highlight the role of JAK proteins in cancer biology, the most recent developments in targeting JAKs, and the central role they play in intracellular cross-talks with other signaling cascades.

The effect of the JAK2 inhibitor TG101209 against T cell acute lymphoblastic leukemia (T-ALL) is mediated by inhibition of JAK-STAT signaling and activation of the crosstalk between apoptosis and autophagy signaling

Previous reports have shown that active JAK2 contributes to T cell acute lymphoblastic leukaemia (T-ALL) development and that JAK inhibitors may be a potential treatment for T-ALL. In the current study, the JAK2 inhibitor TG101209 was used to treat T-ALL cell lines and primary T-ALL cells. The effects of TG101209 on T-ALL cells were determined, and the signaling proteins related to cell growth, apoptosis and autophagy were analysed. The results indicated that TG101209 significantly inhibited T-ALL cell proliferation and induced cell apoptosis in a dose-dependent manner. The mechanisms involved the suppression of the JAK2-STAT signaling pathway and activation of apoptosis or autophagy. Additionally, a JAK2 gene copy gain (FISH) and up-regulated JAK2, LC3 and Beclin1 expression (western blotting) were observed in T-ALL samples compared with healthy controls, which implied that JAK2 is a target for T-ALL treatment. TG101209 initiated apoptosis and autophagy in T-ALL cells; therefore, this JAK2 inhibitor may be a potential drug or alternative therapy for T-ALL.

Reversine Induced Multinucleated Cells, Cell Apoptosis and Autophagy in Human Non-Small Cell Lung Cancer Cells

Reversine, an A3 adenosine receptor antagonist, has been shown to induce differentiated myogenic-lineage committed cells to become multipotent mesenchymal progenitor cells. We and others have reported that reversine has an effect on human tumor suppression. This study revealed anti-tumor effects of reversine on proliferation, apoptosis and autophagy induction in human non-small cell lung cancer cells. Treatment of these cells with reversine suppressed cell growth in a time- and dosage-dependent manner. Moreover, polyploidy occurred after reversine treatment. In addition, caspase-dependent apoptosis and activation of autophagy by reversine in a dosage-dependent manner were also observed. We demonstrated in this study that reversine contributes to growth inhibition, apoptosis and autophagy induction in human lung cancer cells. Therefore, reversine used as a potential therapeutic agent for human lung cancer is worthy of further investigation.

Afatinib increases sensitivity to radiation in non-small cell lung cancer cells with acquired EGFR T790M mutation

Afatinib is a second-generation of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor and has shown a significant clinical benefit in non-small cell lung cancer (NSCLC) patients with EGFR-activating mutations. However, the potential therapeutic effects of afatinib combining with other modalities, including ionizing radiation (IR), are not well understood. In this study, we developed a gefitinib-resistant cell subline (PC-9-GR) with a secondary EGFR mutation (T790M) from NSCLC PC-9 cells after chronic exposures to increasing doses of gefitinib. The presence of afatinib significantly increases the cell killing effect of radiation in PC-9-GR cells harboring acquired T790M, but not in H1975 cells with de novo T790M or in H460 cells that express wild-type EGFR. In PC-9-GR cells, afatinib remarkable blocks baseline of EGFR and ERK phosphorylations, and causes delay of IR-induced AKT phosphorylation. Afatinib treatment also leads to increased apoptosis and suppressed DNA damage repair in irradiated PC-9-GR cells, and enhanced tumor growth inhibition when combined with IR in PC-9-GR xenografts. Our findings suggest a potential therapeutic impact of afatinib as a radiation sensitizer in lung cancer cells harboring acquired T790M mutation, providing a rationale for a clinical trial with combination of afatinib and radiation in NSCLCs with EGFR T790M mutation.

Small-molecule targeting of signal transducer and activator of transcription (STAT) 3 to treat non-small cell lung cancer

OBJECTIVE

Lung cancer is the leading cause of cancer death in both men and women. Non-small cell lung cancer (NSCLC) has an overall 5-year survival rate of 15%. While aberrant STAT3 activation has previously been observed in NSCLC, the scope of its contribution is uncertain and agents that target STAT3 for treatment are not available clinically.

METHODS

We determined levels of activated STAT3 (STAT3 phosphorylated on Y705, pSTAT3) and the two major isoforms of STAT3 (α and β) in protein extracts of 8 NSCLC cell lines, as well as the effects of targeting STAT3 in vitro and in vivo in NSCLC cells using short hairpin (sh) RNA and two novel small-molecule STAT3 inhibitors, C188-9 and piperlongumine (PL).

RESULTS

Levels of pSTAT3, STAT3α, and STATβ were increased in 7 of 8 NSCLC cell lines. Of note, levels of pSTAT3 were tightly correlated with levels of STAT3β, but not STAT3α. Targeting of STAT3 in A549 cells using shRNA decreased tSTAT3 by 75%; this was accompanied by a 47-78% reduction in anchorage-dependent and anchorage-independent growth and a 28-45% reduction in mRNA levels for anti-apoptotic STAT3 gene targets. C188-9 and PL (@30 μM) each reduced pSTAT3 levels in all NSCLC cell lines tested by ≥50%, reduced anti-apoptotic protein mRNA levels by 25-60%, and reduced both anchorage-dependent and anchorage-independent growth of NSCLC cell lines with IC50 values ranging from 3.06 to 52.44 μM and 0.86 to 11.66 μM, respectively. Treatment of nude mice bearing A549 tumor xenografts with C188-9 or PL blocked tumor growth and reduced levels of pSTAT3 and mRNA encoding anti-apoptotic proteins.

CONCLUSION

STAT3 is essential for growth of NSCLC cell lines and tumors and its targeting using C188-9 or PL may be a useful strategy for treatment.

Effect of the JAK2/STAT3 inhibitor SAR317461 on human glioblastoma tumorspheres

Background

The STAT3 transcription factor is a major intracellular signaling protein and is frequently dysregulated in the most common and lethal brain malignancy in adults, glioblastoma multiforme (GBM). Activation of STAT3 in GBM correlates with malignancy and poor prognosis. The phosphorylating signal transducer JAK2 activates STAT3 in response to cytokines and growth factors. Currently there are no JAK-STAT pathway inhibitors in clinical trials for GBM, so we sought to examine the anti-GBM activity of SAR317461 (Sanofi-Aventis), a newer generation, highly potent JAK2 inhibitor that exhibits low toxicity and good pharmacokinetics. SAR317461 was initially approved for patient testing in the treatment of primary myelofibrosis (PMF), and has shown activity in preclinical models of melanoma and pulmonary cancer, but has not been tested in GBM.

Methods

We hypothesized that a potent small molecule JAK2 inhibitor could overcome the heterogeneous nature of GBM, and suppress a range of patient derived GBM tumorsphere lines and immortalized GBM cell lines. We treated with SAR317461 to determine IC₅₀ values, and using Western blot analysis we asked whether the response was linked to STAT3 expression. Western blot analysis, FACS, and cell viability studies were used to identify the mechanism of SAR317461 induced cell death.

Results

We report for the first time that the JAK2 inhibitor SAR317461 clearly inhibited STAT3 phosphorylation and had substantial activity against cells (IC₅₀ 1–10 µM) from 6 of 7 different patient GSC derived GBM tumorsphere lines and three immortalized GBM lines. One patient GSC derived line did not constitutively express STAT3 and was more resistant to SAR317461 (IC₅₀ ≈25 µM). In terms of mechanism we found cleaved PARP and clear apoptosis following SAR317461. SAR317461 also induced autophagy and the addition of an autophagy inhibitor markedly enhanced cell killing by SAR317461.

Conclusions

We conclude that SAR317461 potently inhibits STAT3 phosphorylation and that it has significant activity against those GBM cells which express activated STAT3. Further studies are warranted in terms of the potential of SAR317461 as single and combined therapy for selectively treating human patients afflicted with GBMs expressing activation of the JAK2-STAT3 signaling axis.

STAT3: A Novel Molecular Mediator of Resistance to Chemoradiotherapy

Chemoradiotherapy (CRT) represents a standard treatment for many human cancers, frequently combined with radical surgical resection. However, a considerable percentage of primary cancers are at least partially resistant to CRT, which represents a substantial clinical problem, because it exposes cancer patients to the potential side effects of both irradiation and chemotherapy. It is therefore exceedingly important to determine the molecular characteristics underlying CRT-resistance and to identify novel molecular targets that can be manipulated to re-sensitize resistant tumors to CRT. In this review, we highlight much of the recent evidence suggesting that the signal transducer and activator of transcription 3 (STAT3) plays a prominent role in mediating CRT-resistance, and we outline why inhibition of STAT3 holds great promise for future multimodal treatment concepts in oncology.

Molecular markers to predict clinical outcome and radiation induced toxicity in lung cancer

The elucidation of driver mutations involved in the molecular pathogenesis of cancer has led to a surge in the application of novel targeted therapeutics in lung cancer. Novel oncologic research continues to lead investigators towards targeting personalized tumor characteristics rather than applying targeted therapy to broad patient populations. Several driver genes, in particular epidermal growth factor receptor (EGFR) and ALK fusions, are the earliest to have made their way into clinical trials. The avant-garde role of genomic profiling has led to important clinical challenges when adapting current standard treatments to personalized oncologic care. This new frontier of medicine requires newer biomarkers for toxicity that will identify patients at risk, as well as, new molecular markers to predict and assess clinical outcomes. Thus far, several signature genes have been developed to predict outcome as well as genetic factors related to inflammation to predict toxicity.

Targeting the tumor microenvironment: JAK-STAT3 signaling

Persistent JAK-STAT3 signaling is implicated in many aspects of tumorigenesis. Apart from its tumor-intrinsic effects, STAT3 also exerts tumor-extrinsic effects, supporting tumor survival and metastasis. These involve the regulation of paracrine cytokine signaling, alterations in metastatic sites rendering these permissive for the growth of cancer cells and subversion of host immune responses to create an immunosuppressive environment. Targeting this signaling pathway is considered a novel promising therapeutic approach, especially in the context of tumor immunity. In this article, we will review to what extent JAK-STAT3-targeted therapies affect the tumor microenvironment and whether the observed effects underlie responsiveness to therapy.

PARP inhibitor attenuated colony formation can be restored by MAP kinase inhibitors in different irradiated cancer cell lines

Abstract Purpose: Sensitizing cancer cells to irradiation is a major challenge in clinical oncology. We aimed to define the signal transduction pathways involved in poly(ADP-ribose) polymerase (PARP) inhibitor-induced radiosensitization in various mammalian cancer lines.

MATERIALS AND METHODS

Clonogenic survival assays and Western blot examinations were performed following telecobalt irradiation of cancer cells in the presence or absence of various combinations of PARP- and selective mitogen-activated protein kinase (MAPK) inhibitors.

RESULTS

HO3089 resulted in significant cytotoxicity when combined with irradiation. In human U251 glioblastoma and A549 lung cancer cell lines, Erk1/2 and JNK/SAPK were found to mediate this effect of HO3089 since inhibitors of these kinases ameliorated it. In murine 4T1 breast cancer cell line, p38 MAPK rather than Erk1/2 or JNK/SAPK was identified as the main mediator of HO3089's radiosensitizing effect. Besides the aforementioned changes in kinase signaling, we detected increased p53, unchanged Bax and decreased Bcl-2 expression in the A549 cell line.

CONCLUSIONS

HO3089 sensitizes cancer cells to photon irradiation via proapoptotic processes where p53 plays a crucial role. Activation of MAPK pathways is regarded the consequence of irradiation-induced DNA damage, thus their inhibition can counteract the radiosenzitizing effect of the PARP inhibitor.

The Role of STAT3 in Non-Small Cell Lung Cancer

Persistent phosphorylation of signal transducer and activator of transcription 3 (STAT3) has been demonstrated in 22%~65% of non-small cell lung cancers (NSCLC). STAT3 activation is mediated by receptor tyrosine kinases, such as epidermal growth factor receptor (EGFR) and MET, cytokine receptors, such as IL-6, and non-receptor kinases, such as Src. Overexpression of total or phosphorylated STAT3 in resected NSCLC leads to poor prognosis. In a preclinical study, overexpression of STAT3 was correlated with chemoresistance and radioresistance in NSCLC cells. Here, we review the role of STAT3 and the mechanisms of treatment resistance in malignant diseases, especially NSCLC. As STAT3 is a critical mediator of the oncogenic effects of EGFR mutations, we discuss STAT3 pathways in EGFR-mutated NSCLC, referring to mechanisms of EGFR tyrosine kinase inhibitor resistance.

ERK1/2 inhibition enhances apoptosis induced by JAK2 silencing in human gastric cancer SGC7901 cells

Recent studies suggest JAK2 signaling may be a therapeutic target for treatment of gastric cancer (GC). However, the exact roles of JAK2 in gastric carcinogenesis are not very clear. Here, we have targeted JAK2 to be silenced by shRNA and investigated the biological functions and related mechanisms of JAK2 in GC cell SGC7901. In this study, JAK2 is commonly highly expressed in GC tissues as compared to their adjacent normal tissues (n = 75, p < 0.01). Specific down-regulation of JAK2 suppressed cell proliferation and colony-forming units, induced G2/M arrest in SGC7901 cells, but had no significant effect on cell apoptosis in vitro or tumor growth inhibition in vivo. Interestingly, JAK2 silencing-induced activation of ERK1/2, and inactivation of ERK1/2 using the specific ERK inhibitor PD98059 markedly enhanced JAK2 shRNA-induced cell proliferation inhibition, cell cycle arrest and apoptosis. Ultimately, combination of PD98059 and JAK2 shRNA significantly inhibited tumor growth in nude mice. Our results implicate JAK2 silencing-induced cell proliferation inhibition, cell cycle arrest, and ERK1/2 inhibition could enhance apoptosis induced by JAK2 silencing in SGC7901 cells.

Honokiol as a Radiosensitizing Agent for Colorectal cancers

Radioresistance is a frustrating obstacle for patients with colorectal cancers (CRCs) undergoing radiotherapy. There is an urgent need to find an effective agent to increase the sensitivity of CRCs to radiation. Honokiol, an active compound purified from Magnolia, was found to radiosensitize colorectal cancer cells both in vitro and in vivo. However, the mechanisms control important signaling that enhances radiosensitivity is currently unknown. In this study, we have reviewed important signaling pathways that are closely related to radiosensitization, such as cell cycle arrest, tumor angiogenesis, JAK/STAT3 signaling pathway and Mismatch repair. Studies show that honokiol can interfere with these pathways at different levels. With overall analysis, it may bring light on finding the possible mechanism by which honokiol acts as a radiosensitizing agent for CRCs.

Soluble interleukin-6 receptor is a serum biomarker for the response of esophageal carcinoma to neoadjuvant chemoradiotherapy

Preoperative chemoradiotherapy has been shown to improve the outcome of patients with esophageal cancer, but because response to this therapy varies, it is desirable to identify in advance individuals who would be unlikely to benefit, in order to avoid unnecessary adverse drug effects. The serum profiles of 84 cytokines and related proteins were determined in 37 patients with esophageal squamous cell carcinoma who received identical neoadjuvant preoperative chemoradiotherapy regimens and underwent surgical resection. Histological response to this therapy was assessed in surgically resected specimens. The serum soluble interleukin-6 receptor (sIL6R) level was significantly higher in 30 patients who failed to achieve a histological complete response (P = 0.005). Multivariate analysis revealed that the increased level of sIL6R was one of several significant independent predictors of an unfavorable outcome (hazard ratio, 2.87; P = 0.017). The increased level of this cytokine in patients who did not obtain a complete response was reproducibly observed in an independent cohort of 34 patients. Esophageal squamous cell carcinoma patients with an increased serum level of sIL6R are predicted to respond poorly to preoperative chemoradiotherapy, therefore, their exclusion from this treatment may be considered. Persistent systemic inflammation is implicated as a possible mechanism of resistance to this therapy.