Mutations leading to constitutive active gp130/JAK1/STAT3 pathway

Mechanisms and therapeutic prospect of the JAK-STAT signaling pathway in liver cancer

Liver cancer (LC) poses a significant global health challenge due to its high incidence and poor prognosis. Current systemic treatment options, such as surgery, chemotherapy, radiofrequency ablation, and immunotherapy, have shown limited effectiveness for advanced LC patients. Moreover, owing to the heterogeneous nature of LC, it is crucial to uncover more in-depth pathogenic mechanisms and develop effective treatments to address the limitations of the existing therapeutic modalities. Increasing evidence has revealed the crucial role of the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway in the pathogenesis of LC. The specific mechanisms driving the JAK-STAT pathway activation in LC, participate in a variety of malignant biological processes, including cell differentiation, evasion, anti-apoptosis, immune escape, and treatment resistance. Both preclinical and clinical investigations on the JAK-STAT pathway inhibitors have exhibited potential in LC treatment, thereby opening up avenues for the development of more targeted therapeutic strategies for LC. In this study, we provide an overview of the JAK-STAT pathway, delving into the composition, activation, and dynamic interplay within the pathway. Additionally, we focus on the molecular mechanisms driving the aberrant activation of the JAK-STAT pathway in LC. Furthermore, we summarize the latest advancements in targeting the JAK-STAT pathway for LC treatment. The insights presented in this review aim to underscore the necessity of research into the JAK-STAT signaling pathway as a promising avenue for LC therapy.

Study of sex-biased differences in genomic profiles in East Asian hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is characterized by a notable sex disparity in incidence and tumor aggressiveness. Revealing differences in genetic landscapes between male and female HCCs may expand the understanding of sexual disparities mechanisms and assist the development of precision medicine. Although reports on the sex disparity of HCC are accumulated, studies focusing on sex-related biomarkers among Asian populations remain limited. Here, we conducted a comprehensive genomic profiling analysis to explore differences between male and female patients within a cohort of 195 Taiwanese HCC patients. We did not detect any sex-biased genomic alterations. However, when our investigation extended to the TCGA dataset, we found higher frequencies of gene copy gains in CCNE2 and mutations in CTNNB1 and TP53 among male patients. Besides, we further evaluated the associations between genomic alterations and patients' prognosis by sex. The results showed that female patients harboring tumors with STAT3 gain and alterations in the JAK-STAT pathway displayed a poor prognosis. These two factors remained independently associated with unfavorable prognosis even after adjusting for the patient's age and stage characteristics (Hazard ratio = 10.434, 95% CI 3.331-32.677, P < 0.001; Hazard ratio = 2.547, 95% CI 1.195-5.432, P = 0.016, respectively). In summary, this study provides valuable insights into understanding sex disparity in HCC in the East Asian population. Validation through larger cohorts and extensive sequencing efforts is warranted.

Overexpression of MiR-188-5p Downregulates IL6ST/STAT3/ NLRP3 Pathway to Ameliorate Neuron Injury in Oxygen-glucose Deprivation/Reoxygenation

BACKGROUND

CI/R, characterized by ischemic injury following abrupt reestablishment of blood flow, can cause oxidative stress, mitochondrial dysfunction, and apoptosis. We used oxygen-glucose deprivation/reoxygenation (OGD/R) induced injury in HT22 and primary mouse cortical neurons (MCN) as a model for CI/R.

OBJECTIVE

This study investigates the role of miR-188-5p in hippocampal neuron cell injury associated with Cerebral Ischemia-Reperfusion (CI/R).

METHODS

HT22 and MCN cells were induced by OGD/R to construct an in vitro model of CI/R. Cell apoptosis and proliferation were assessed using flow cytometry and the Cell Counting Kit-8 (CCK8). ELISA was conducted to measure the levels of IL-1β, IL-6, and TNF-α. Moreover, the interaction between miR-188-5p and IL6ST was investigated using dual luciferase assay, the expression of miR-188-5p, Bax, cleaved-caspase3, IL-6, Bcl-2, IL-1β, TNF-α, IL6ST, NFκB, NLRP3 and STAT3 was evaluated using RT-qPCR or Western blot, and immunofluorescence was used to analyze the co-expression of p-STAT3 and NLRP3 in neuronal cells.

RESULTS

OGD/R reduced proliferation and miR-188-5p levels and increased IL6ST expression, inflammation, and apoptosis in HT22 and MCN cells. Moreover, miR-188-5p was found to bind to IL6ST. Mimics of miR-188-5p reduced apoptosis, lowered the expression of cleaved-caspase3 and Bax proteins, and elevated Bcl-2 protein expression in cells treated with OGD/R. Overexpression of miR-188-5p decreased the levels of NLRP3 and p-STAT3 in the OGD/R group. Furthermore, the overexpression of miR-188-5p reduced IL6ST, p- NFκB/NFκB, p-STAT3/STAT3, and NLRP3 proteins in OGD/R, and these effects could be reversed by IL6ST overexpression.

CONCLUSION

Mimics of miR-188-5p were found to inhibit inflammation and the STAT3/NLRP3 pathway via IL6ST, thereby ameliorating injury in HT22 and MCN cells treated with OGD/R in the context of CI/R.

Hexahydrocurcumin from Zingiberis rhizoma attenuates lipopolysaccharide-induced acute pneumonia through JAK1/STAT3 signaling pathway

BACKGROUND

Pneumonia is one of the major causes of death after pathogens infection. Zingiberis rhizoma (GAN JIANG) is a herb that used in combination with other Chinese medicines to treat pathogen such as virus induced pneumonia. However, the affect of hexahydrocurcumin (HHC), a component from Zingiberis rhizoma, on pneumonia remains unknown.

PURPOSE

This study aims to explore the effects of HHC on lipopolysaccharide (LPS)-induced acute pneumonia, and to clarify the underlying mechanism.

METHODS

The pneumonia model of C57BL/6 mice was established by intratracheal injection of LPS to evaluate the therapeutic effect of HHC on lung injury and inflammation in vivo. RAW264.7 macrophages were utilized to illustrate the cellular mechanism of HHC in vitro.

RESULTS

HHC alleviated lung injury, ROS and inflammatory cytokine IL-6 production in pneumonia mice in vivo. Molecular docking results disclosed the binding of HHC to JAK1 protein. The study further showed that HHC suppressed the inflammatory cytokines such as IL-6, TNF-α, IL-1β gene expression, inhibited the phosphorylation of JAK1 but not JAK3, and the subsequent STAT3 phosphorylation in LPS-activated macrophages. HHC exhibited no effects on the protein levels of JAK1 and STAT3 in vitro. Consistently, HHC also attenuated the JAK1, STAT3 phosphorylation in pneumonia mice in vivo.

CONCLUSION

The results reveal that HHC attenuates pneumonia by targeted inhibition of JAK1/STAT3 signaling pathway. It indicates the novel role of HHC to treat pneumonia, and its potential applications for JAK inhibitor-treated diseases.

CRP Versus SAA for Identification of Inflammatory Hepatic Adenomas

Subtyping hepatic adenomas is important for patient management due to differing complication risks. Immunohistochemical staining with C-reactive protein (CRP) and serum amyloid-A (SAA) is widely accepted as a surrogate for molecular classification to identify inflammatory hepatocellular adenomas. Limited data, however, has been published on how these 2 stains compare for sensitivity. We conducted a large, multicenter, retrospective study to examine the sensitivity and staining characteristics of CRP and SAA in inflammatory hepatic adenomas, with focal nodular hyperplasia (FNHs) as a control group. Inflammatory adenomas were identified in 133 patients (average age 37 years, 109 were female). In all, 69.9% of cases were resection specimens and 90.2% of all cases showed positive staining for both CRP and SAA; 10 (7.5%) were positive for CRP only and 3 (2.3%) were positive for SAA only. CRP was more sensitive than SAA (97.74% vs. 92.48%, P -value = 0.0961) and showed more extensive and intense staining, with a significantly higher modified H-score ( P <0.001). Focal nodular hyperplasia can also show positive CRP and SAA staining but with a lower modified H-score ( P <0.0001). Based on beta-catenin and glutamine synthetase staining, 26 of inflammatory adenomas also had beta-catenin activation (19.5%). All 3 cases with positive SAA and negative CRP staining were beta-catenin activated. In contrast, the proportion of cases that were CRP positive and SAA negative was similar regardless of beta-catenin activation. The data affirms the strategy of using both CRP and SAA immunostains for hepatic adenoma subtyping and raises the awareness of the highly variable nature of SAA staining characteristics.

Exploring the JAK/STAT Signaling Pathway in Hepatocellular Carcinoma: Unraveling Signaling Complexity and Therapeutic Implications

Hepatocellular Carcinoma (HCC) continues to pose a substantial global health challenge due to its high incidence and limited therapeutic options. In recent years, the Janus Kinase (JAK) and Signal Transducer and Activator of Transcription (STAT) pathway has emerged as a critical signaling cascade in HCC pathogenesis. The review commences with an overview of the JAK/STAT pathway, delving into the dynamic interplay between the JAK/STAT pathway and its numerous upstream activators, such as cytokines and growth factors enriched in pathogenic livers afflicted with chronic inflammation and cirrhosis. This paper also elucidates how the persistent activation of JAK/STAT signaling leads to diverse oncogenic processes during hepatocarcinogenesis, including uncontrolled cell proliferation, evasion of apoptosis, and immune escape. In the context of therapeutic implications, this review summarizes recent advancements in targeting the JAK/STAT pathway for HCC treatment. Preclinical and clinical studies investigating inhibitors and modulators of JAK/STAT signaling are discussed, highlighting their potential in suppressing the deadly disease. The insights presented herein underscore the necessity for continued research into targeting the JAK/STAT signaling pathway as a promising avenue for HCC therapy.

Pharmacological updates of nifuroxazide: Promising preclinical effects and the underlying molecular mechanisms

Nifuroxazide (NFX) is a safe nitrofuran antibacterial drug used clinically to treat acute diarrhea and infectious traveler diarrhea or colitis. Recent studies revealed that NFX displays multiple pharmacological effects, including anticancer, antioxidant, and anti-inflammatory effects. NFX has potential roles in inhibiting thyroid, breast, lung, bladder, liver, and colon cancers and osteosarcoma, melanoma, and others mediated by suppressing STAT3 as well as ALDH1, MMP2, MMP9, Bcl2 and upregulating Bax. Moreover, it has promising effects against sepsis-induced organ injury, hepatic disorders, diabetic nephropathy, ulcerative colitis, and immune disorders. These promising effects appear to be mediated by suppressing STAT3 as well as NF-κB, TLR4, and β-catenin expressions and effectively decreasing downstream cytokines TNF-α, IL-1β, and IL-6. Our review summarizes the available studies on the molecular biological mechanisms of NFX in cancer and other diseases and it is recommended to translate the studies in experimental animals and cultured cells and repurpose NFX in various diseases for scientific evidence based on human studies.

The Flavagline Compound 1-(2-(dimethylamino)acetyl)-Rocaglaol Induces Apoptosis in K562 Cells by Regulating the PI3K/Akt/mTOR, JAK2/STAT3, and MAPK Pathways

Purpose

Methods

Results

Conclusion

Spatiotemporal gating of Stat nuclear influx by Drosophila Npas4 in collective cell migration

Collective migration is important to embryonic development and cancer metastasis, but migratory and nonmigratory cell fate discrimination by differential activity of signal pathways remains elusive. In Drosophila oogenesis, Jak/Stat signaling patterns the epithelial cell fates in early egg chambers but later renders motility to clustered border cells. How Jak/Stat signal spatiotemporally switches static epithelia to motile cells is largely unknown. We report that a nuclear protein, Dysfusion, resides on the inner nuclear membrane and interacts with importin α/β and Nup153 to modulate Jak/Stat signal by attenuating Stat nuclear import. Dysfusion is ubiquitously expressed in oogenesis but specifically down-regulated in border cells when migrating. Increase of nuclear Stat by Dysfusion down-regulation triggers invasive cell behavior and maintains persistent motility. Mammalian homolog of Dysfusion (NPAS4) also negatively regulates the nuclear accumulation of STAT3 and cancer cell migration. Thus, our finding demonstrates that Dysfusion-dependent gating mechanism is conserved and may serve as a therapeutic target for Stat-mediated cancer metastasis.

Identification of serum and glucocorticoid-regulated kinase 1 as a regulator of signal transducer and activator of transcription 3 signaling

Signal transducer and activator of transcription 3 (STAT3) plays key roles in cancer cell proliferation, invasion, and immunosuppression. In many human cancer cells, STAT3 is hyperactivated, which leads to tumor progression and drug resistance, and therefore STAT3 and its modulators are considered effective drug targets. However, the complex regulatory mechanisms of STAT3 have made it difficult to develop potent anticancer drugs that suppress its activity. Here, we report serum and glucocorticoid-regulated kinase 1 (SGK1) as a novel regulator of STAT3 signaling and an effective target for combination therapy with Janus kinase (JAK) inhibitors. We screened small molecules using a gain-of-function mutant of STAT3 resistant to JAK inhibition and found that an SGK1 inhibitor suppressed the constitutive activation of STAT3. Importantly, our results revealed that SGK1 also mediated the activation of wild-type STAT3. Further examination suggested that the tuberous sclerosis complex 2 and mammalian target of rapamycin signaling pathway were involved in STAT3 activation by SGK1. Finally, we demonstrated that SGK1 inhibition enhanced the inhibitory effect of a JAK inhibitor on STAT3 phosphorylation and cancer cell proliferation. Our findings provide new insights into the molecular mechanisms of STAT3 activation and suggest SGK1 as a potential target for STAT3-targeted combination cancer therapy.

Leptin Receptor Overlapping Transcript (LEPROT) Is Associated with the Tumor Microenvironment and a Prognostic Predictor in Pan-Cancer

Background

Leptin receptor overlapping transcript (LEPROT) is reported to be involved in metabolism regulation and energy balance as well as molecular signaling of breast cancer and osteosarcoma. LEPROT is expressed in various tissue and is suggested to be involved in cancer developments but with contradictory roles. The comprehensive knowledge of the effects of LEPROT on cancer development and progression across pan-cancer is still missing.

Methods

The expressions of LEPROT in cancers were compared with corresponding normal tissues across pan-cancer types. The relationships between expression and methylation of LEPROT were then demonstrated. The correlations of LEPROT with the tumor microenvironment (TME), including immune checkpoints, tumor immune cells infiltration (TII), and cancer-associated fibroblasts (CAFs), were also investigated. Co-expression analyses and functional enrichments were conducted to suggest the most relevant genes and the mechanisms of the effects in cancers for LEPROT. Finally, the correlations of LEPROT with patient survival and immunotherapy response were explored.

Results

LEPROT expression was found to be significantly aberrant in 15/19 (78.9%) cancers compared with corresponding normal tissues; LEPROT was downregulated in 12 cancers and upregulated in three cancers. LEPROT expressions were overall negatively correlated with its methylation alterations. Moreover, LEPROT was profoundly correlated with the TME, including immune checkpoints, TIIs, and CAFs. According to co-expression analyses and functional enrichments, the interactions of LEPROT with the TME may be mediated by the interleukin six signal transducer/the Janus kinase/signal transducers and activators of the transcription signaling pathway. Prognostic values may exist for LEPROT to predict patient survival and immunotherapy response in a context-dependent way.

Conclusions

LEPROT affects cancer development by interfering with the TME and regulating inflammatory or immune signals. LEPROT may also serve as a potential prognostic marker or a target in cancer therapy. This is the first study to investigate the roles of LEPROT across pan-cancer.

The IL6-like Cytokine Family: Role and Biomarker Potential in Breast Cancer

IL6-like cytokines are a family of regulators with a complex, pleiotropic role in both the healthy organism, where they regulate immunity and homeostasis, and in different diseases, including cancer. Here we summarise how these cytokines exert their effect through the shared signal transducer IL6ST (gp130) and we review the extensive evidence on the role that different members of this family play in breast cancer. Additionally, we discuss how the different cytokines, their related receptors and downstream effectors, as well as specific polymorphisms in these molecules, can serve as predictive or prognostic biomarkers with the potential for clinical application in breast cancer. Lastly, we also discuss how our increasing understanding of this complex signalling axis presents promising opportunities for the development or repurposing of therapeutic strategies against cancer and, specifically, breast neoplasms.

Proteomic Profiling of Hepatocellular Adenomas Paves the Way to Diagnostic and Prognostic Approaches

BACKGROUND AND AIMS

Through an exploratory proteomic approach based on typical hepatocellular adenomas (HCAs), we previously identified a diagnostic biomarker for a distinctive subtype of HCA with high risk of bleeding, already validated on a multicenter cohort. We hypothesized that the whole protein expression deregulation profile could deliver much more informative data for tumor characterization. Therefore, we pursued our analysis with the characterization of HCA proteomic profiles, evaluating their correspondence with the established genotype/phenotype classification and assessing whether they could provide added diagnosis and prognosis values.

APPROACH AND RESULTS

From a collection of 260 cases, we selected 52 typical cases of all different subgroups on which we built a reference HCA proteomics database. Combining laser microdissection and mass-spectrometry-based proteomic analysis, we compared the relative protein abundances between tumoral (T) and nontumoral (NT) liver tissues from each patient and we defined a specific proteomic profile of each of the HCA subgroups. Next, we built a matching algorithm comparing the proteomic profile extracted from a patient with our reference HCA database. Proteomic profiles allowed HCA classification and made diagnosis possible, even for complex cases with immunohistological or genomic analysis that did not lead to a formal conclusion. Despite a well-established pathomolecular classification, clinical practices have not substantially changed and the HCA management link to the assessment of the malignant transformation risk remains delicate for many surgeons. That is why we also identified and validated a proteomic profile that would directly evaluate malignant transformation risk regardless of HCA subtype.

CONCLUSIONS

This work proposes a proteomic-based machine learning tool, operational on fixed biopsies, that can improve diagnosis and prognosis and therefore patient management for HCAs.

SP2509, an inhibitor of LSD1, exerts potential antitumor effects by targeting the JAK/STAT3 signaling

Hyperactivation of Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling promotes tumorigenesis and cancer progression. STAT3 participates in the essential processes of cell proliferation, survival, and differentiation in many types of tumors. In the present study, SP2509 was identified as a potent inhibitor of the JAK/STAT3 signaling pathway by high-throughput drug screening based on a STAT3-driven luciferase expression system. Our results indicated that SP2509 inhibits constitutive STAT3 activation and the expression of STAT3-driven downstream genes. Bcl-xL, c-Myc, and Cyclin D1 were downregulated after treatment with SP2509. In addition, SP2509 specifically inhibits JAK activity, which could cause cell cycle arrest, inhibit cell growth, and induce apoptosis of various cancer cells. These results confirmed that SP2509 inhibits tumor progression by suppressing the expression of JAK/STAT3 signaling and STAT3-related downstream genes. Moreover, we demonstrated that SP2509 inhibits tumor growth in vivo and induces cell death in vitro. SP2509-mediated inhibition of STAT3 phosphorylation is dependent on its original target lysine-specific demethylase 1 in cancer cells. In summary, our results indicate that SP2509 is a novel inhibitor of JAK/STAT3 signaling.

Somatic Mutations in Circulating Cell-Free DNA and Risk for Hepatocellular Carcinoma in Hispanics

Hispanics are disproportionally affected by liver fibrosis and hepatocellular carcinoma (HCC). Advanced liver fibrosis is a major risk factor for HCC development. We aimed at identifying somatic mutations in plasma cell-free DNA (cfDNA) of Hispanics with HCC and Hispanics with advanced liver fibrosis but no HCC. Targeted sequencing of over 262 cancer-associated genes identified nonsynonymous mutations in 22 of the 27 HCC patients. Mutations were detected in known HCC-associated genes (e.g., CTNNB1, TP53, NFE2L2, and ARID1A). No difference in cfDNA concentrations was observed between patients with mutations and those without detectable mutations. HCC patients with higher cfDNA concentrations or higher number of mutations had a shorter overall survival (p < 0.001 and p = 0.045). Nonsynonymous mutations were also identified in 17 of the 51 subjects with advanced liver fibrosis. KMT2C was the most commonly mutated gene. Nine genes were mutated in both subjects with advanced fibrosis and HCC patients. Again, no significant difference in cfDNA concentrations was observed between subjects with mutations and those without detectable mutations. Furthermore, higher cfDNA concentrations and higher number of mutations correlated with a death outcome in subjects with advanced fibrosis. In conclusion, cfDNA features are promising non-invasive markers for HCC risk prediction and overall survival.

A Shifting Paradigm in Diagnosis and Management of Hepatic Adenoma

BACKGROUND

New insights into molecular pathogenesis of hepatocellular adenomas (HCA) have allowed sub-classification based on distinct genetic alterations and a fresh look at characterizations of natural history. Clinically, this is important in understanding risk factors for two feared complications: malignant transformation and hemorrhage.

METHODS

PubMed literature search for hepatocellular adenoma over all years, excluding case reports and articles focusing on multiple adenomas or adenomatosis.

RESULTS

The β-catenin exon 3 mutated HCA accounts for about 10% of all HCAs and is associated with the highest risk of malignant transformation. The HF1α subtype accounts for 30-40% of all HCAs and has the lowest risk of malignant transformation. Gender has also emerged as an increasingly important risk factor and males with HCA are at considerably higher risk of malignant transformation, regardless of tumor size. The increasing use of gadoxetic-enhanced MRI has allowed for improved differentiation of HCAs from focal nodular hyperplasia, as well as the identification of specific radiologic features of some subtypes, particularly the inflammatory and HF1α HCAs.

CONCLUSIONS

Classification of HCA by subtype has important implications for patient counseling and treatment given variable risks of malignant transformation and hemorrhage. Males and those with β-catenin exon 3 mutated HCAs are two groups who should always be counselled to undergo surgical resection. On the other hand, in the lower risk HF1α subtype observation is appropriate in lesions < 5 cm and may even be considered in larger lesions as longer follow-up data is aggregated and tumorigenesis is better understood.

Can asymmetric post-translational modifications regulate the behavior of STAT3 homodimers?

Signal transducer and activator of transcription 3 (STAT3) is a ubiquitous and pleiotropic transcription factor that plays essential roles in normal development, immunity, response to tissue damage and cancer. We have developed a Venus-STAT3 bimolecular fluorescence complementation assay that allows the visualization and study of STAT3 dimerization and protein-protein interactions in living cells. Inactivating mutations on residues susceptible to post-translational modifications (PTMs) (K49R, K140R, K685R, Y705F and S727A) changed significantly the intracellular distribution of unstimulated STAT3 dimers when the dimers were formed by STAT3 molecules that carried different mutations (ie they were "asymmetric"). Some of these asymmetric dimers changed the proliferation rate of HeLa cells. Our results indicate that asymmetric PTMs on STAT3 dimers could constitute a new level of regulation of STAT3 signaling. We put forward these observations as a working hypothesis, since confirming the existence of asymmetric STAT3 homodimers in nature is extremely difficult, and our own experimental setup has technical limitations that we discuss. However, if our hypothesis is confirmed, its conceptual implications go far beyond STAT3, and could advance our understanding and control of signaling pathways.

Hepatocellular adenoma(s) arising in nodular regenerative hyperplasia in a patient with systemic lupus erythematosus

Hepatocellular adenoma (HCA) is a rare benign tumor of the liver with low risk of malignant transformation. It is associated with oral contraceptives/anabolic steroid use, metabolic disease, and rarely, vascular abnormalities. We report an interesting case of HCA arising in a background of diffuse hepatic nodular regenerative hyperplasia (NRH) in a 40-year-old female patient with systemic lupus erythematosus (SLE). She presented with sudden-onset refractory ascites, elevated liver enzymes, diffuse hepatic nodularity and mass lesions on imaging concerning for malignancy. Targeted biopsies of the mass lesion were performed with inconclusive diagnoses. The patient ultimately underwent resection of the mass, which was confirmed as HCA, inflammatory type, arising in a background of NRH. It is not uncommon for SLE patients to have liver manifestations such as NRH, but HCA arising in NRH has not been previously reported. Our case reveals an unusual relationship between HCA and hepatic vasculopathy in the clinical context of a systemic inflammatory condition, the mechanism by which is not fully understood.

Revisiting signal transducer and activator of transcription 3 (STAT3) as an anticancer target and its inhibitor discovery: Where are we and where should we go?

As a transcription factor, STAT3 protein transduces extracellular signals to the nucleus and then activates transcription of target genes. STAT3 has been well validated as an attractive anticancer target due to its important roles in cancer initiation and progression. Identification of specific and potent STAT3 inhibitors has attracted much attention, while there has been no STAT3 targeted drug approved for clinical application. In this review, we will briefly introduce STAT3 protein and review its role in multiple aspects of cancer, and systematically summarize the recent advances in discovery of STAT3 inhibitors, especially the ones discovered in the past five years. In the last part of the review, we will discuss the possible new strategies to overcome the difficulties of developing potent and specific STAT3 inhibitors and hope to shed light on future drug design and inhibitor optimization.

Nucleocytoplasmic Shuttling of STATs. A Target for Intervention?

Signal transducer and activator of transcription (STAT) proteins are transcription factors that in the latent state are located predominantly in the cytoplasm. Activation of STATs through phosphorylation of a single tyrosine residue results in nuclear translocation. The requirement of tyrosine phosphorylation for nuclear accumulation is shared by all STAT family members but mechanisms of nuclear translocation vary between different STATs. These differences offer opportunities for specific intervention. To achieve this, the molecular mechanisms of nucleocytoplasmic shuttling of STATs need to be understood in more detail. In this review we will give an overview on the various aspects of nucleocytoplasmic shuttling of latent and activated STATs with a special focus on STAT3 and STAT5. Potential targets for cancer treatment will be identified and discussed.

A Potent and Selective Small-Molecule Degrader of STAT3 Achieves Complete Tumor Regression In Vivo

Signal transducer and activator of transcription 3 (STAT3) is an attractive cancer therapeutic target. Here we report the discovery of SD-36, a small-molecule degrader of STAT3. SD-36 potently induces the degradation of STAT3 protein in vitro and in vivo and demonstrates high selectivity over other STAT members. Induced degradation of STAT3 results in a strong suppression of its transcription network in leukemia and lymphoma cells. SD-36 inhibits the growth of a subset of acute myeloid leukemia and anaplastic large-cell lymphoma cell lines by inducing cell-cycle arrest and/or apoptosis. SD-36 achieves complete and long-lasting tumor regression in multiple xenograft mouse models at well-tolerated dose schedules. Degradation of STAT3 protein, therefore, is a promising cancer therapeutic strategy.

Jak-Stat Signaling Induced by Interleukin-6 Family Cytokines in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors worldwide. It can be caused by chronic liver cell injury with resulting sustained inflammation, e.g., triggered by infections with hepatitis viruses B (HBV) and C (HCV). Death of hepatocytes leads to the activation of compensatory mechanisms, which can ultimately result in liver fibrosis and cirrhosis. Another common feature is the infiltration of the liver with inflammatory cells, which secrete cytokines and chemokines that act directly on the hepatocytes. Among several secreted proteins, members of the interleukin-6 (IL-6) family of cytokines have emerged as important regulatory proteins that might constitute an attractive target for therapeutic intervention. The IL-6-type cytokines activate multiple intracellular signaling pathways, and especially the Jak/STAT cascade has been shown to be crucial for HCC development. In this review, we give an overview about HCC pathogenesis with respect to IL-6-type cytokines and the Jak/STAT pathway. We highlight the role of mutations in genes encoding several proteins involved in the cytokine/Jak/STAT axis and summarize current knowledge about IL-6 family cytokines in this context. We further discuss possible anti-cytokine therapies for HCC patients in comparison to already established therapies.

Naturally occurring and synthetic constitutive-active cytokine receptors in disease and therapy

Cytokines control immune related events and are critically involved in a plethora of patho-physiological processes including autoimmunity and cancer development. Mutations which cause ligand-independent, constitutive activation of cytokine receptors are quite frequently found in diseases. Many constitutive-active cytokine receptor variants have been directly connected to disease development and mechanistically analyzed. Nature's solutions to generate constitutive cytokine receptors has been recently adopted by synthetic cytokine receptor biology, with the goal to optimize immune therapeutics. Here, CAR T cell immmunotherapy represents the first example to combine synthetic biology with genetic engineering during therapy. Hence, constitutive-active cytokine receptors are therapeutic targets, but also emerging tools to improve or modulate immunotherapeutic strategies. This review gives a comprehensive insight into the field of naturally occurring and synthetic constitutive-active cytokine receptors.

Synchronous Unicentric Castleman Disease and Inflammatory Hepatocellular Adenoma: a Case Report

Systemic symptoms such as fever and fatigue are non-specific manifestations spanning from inflammation to neoplasia. Here we report the case of a 34 year-old man who presented with systemic symptoms for four months. CT-scan and MRI revealed a 3.4 cm arterialized hepatic lesion and a 7 cm paraduodenal mass. Surgical resection of both lesions and histological examination revealed an inflammatory hepatocellular adenoma and a unicentric plasma cell type of Castleman disease. Moreover, a diffuse AA amyloid deposition in the liver was observed. Resection of both lesions was associated with an improvement of the symptoms. To our knowledge, this is the first report of a synchronous presentation of a unicentric plasma cell type of Castleman disease, inflammatory hepatocellular adenoma and AA amyloidosis.

Activating mutations of the gp130/JAK/STAT pathway in human diseases

Cytokines of the interleukin-6 (IL-6) family are involved in numerous physiological and pathophysiological processes. Dysregulated and increased activities of its members can be found in practically all human inflammatory diseases including cancer. All cytokines activate several intracellular signaling cascades, including the Jak/STAT, MAPK, PI3K, and Src/YAP signaling pathways. Additionally, several mutations in proteins involved in these signaling cascades have been identified in human patients, which render these proteins constitutively active and result in a hyperactivation of the signaling pathway. Interestingly, some of these mutations are associated with or even causative for distinct human diseases, making them interesting targets for therapy. This chapter describes the basic biology of the gp130/Jak/STAT pathway, summarizes what is known about the molecular mechanisms of the activating mutations, and gives an outlook how this knowledge can be exploited for targeted therapy in human diseases.

Prostaglandin E2 triggers cytochrome P450 17α hydroxylase overexpression via signal transducer and activator of transcription 3 phosphorylation and promotes invasion in endometrial cancer

Prostaglandin E2 (PGE2) is the most common prostaglandin in the human body, meaning that its malfunction impacts on the development of numerous diseases. Prostaglandin E synthase 2 (PTGES2) is involved in the synthesis of PGE2. In the present study, immunohistochemistry of PTGES2 was performed in 152 patients with endometrial cancer and in 66 patients with normal endometria. The results indicate a notable association among increased expression of PTGES2 and age (P=0.0092) and the depth of myometrial invasion (P<0.0001). Reverse transcription-quantitative polymerase chain reaction and western blot analysis demonstrated that cytochrome P450 17α hydroxylase (CYP17), an enzyme for androgen synthesis, is overexpressed following PGE2 stimulation via signal transducer and activator of transcription 3 (STAT3) phosphorylation. ELISA also detected increased androgen (testosterone) secretion. Further invasion of endometrial cancer cells was induced at high androgen levels and when CYP17 was overexpressed. Furthermore, the present study observed that CYP17 is overexpressed via STAT3 phosphorylation in endometrial cancer cells, which grow at a high concentration of PGE2, resulting in increased androgen secretion. Concentrations of estrogen and progesterone were not elevated, while the concentration of androgens was. Overall, a high concentration of androgens caused increased invasion of endometrial cancer cells. A high concentration of androgens, which is initiated by a high expression of PTGES2 and a high concentration of PGE2, is an important promoter of myometrial invasion in endometrial cancer.

Unexpected discovery of small HNF1α-inactivated hepatocellular adenoma in pathological specimens from patients resected for liver tumours

BACKGROUND AND AIMS

It is rare but not uncommon to discover micro/small HNF1α-inactivated hepatocellular adenoma (H-HCA) outside the context of resected H-HCA. We aimed to review our cases of micro/small H-HCA discovered by chance on different kinds of liver resected specimens.

METHODS

We retrieved cases of micro/small H-HCA discovered by chance on resected specimens outside the context of H-HCA. All these nodules were liver fatty acid binding protein (LFABP)-negative contrasting with normal positivity in the surrounding non-tumoural liver, ruling out the possibility of focal steatosis or other subtypes of micro-HCAs.

RESULTS

We identified 19 micro/small H-HCA cases. In 16 cases they were discovered in patients who underwent surgery for benign nodules including one haemangioma, six focal nodular hyperplasia, seven inflammatory HCA (including one with b-catenin activation), one HCA, whose subtype could not be identified because of massive necrosis/hemorrhage, and one hepatocellular carcinoma. In two additional cases, patients followed up for a melanoma underwent liver surgery to remove micro nodules possibly related to a metastatic process. Finally in one case a micro nodule was seen and resected during a cholecystectomy.

CONCLUSION

Taken together, H-HCAs are more frequent than we initially supposed as micro and small HCAs cannot all be detected by routine ultrasound. Despite no information on the potential growth of these micro/small H-HCAs, there is no argument to stop oral contraceptives or to ask for a specific regular surveillance. The association of different subtypes of HCAs with focal nodular hyperplasia suggests they share or have common etiological factors.

Roles of STAT3 in leukemia (Review)

Leukemia is a type of hematopoietic malignancy, and the incidence rate in the United States and European Union increases by an average of 0.6 to 0.7% annually. The incidence rate in China is approximately 5.17/100,000 individuals, and the mortality rate is 3.94/100,000 individuals. Leukemia is the most common tumor affecting children and adults under 35 years of age, and is one of the major diseases leading to the death of adolescents. Signal transducer and activator of transcription 3 (STAT3) is a vital regulatory factor of signal transduction and transcriptional activation, and once activated, the phosphorylated form of STAT3 (p-STAT3) is transferred into the nucleus to regulate the transcription of target genes, and plays important roles in cell proliferation, differentiation, apoptosis and other physiological processes. An increasing number of studies have confirmed that the abnormal activation of STAT3 is involved in the development of tumors. In this review, the roles of STAT3 in the pathogenesis, diagnosis, treatment and prognosis of leukemia are discussed in the aspects of cell proliferation, differentiation and apoptosis, with the aim to further clarify the roles of STAT3 in leukemia, and shed light into possible novel targets and strategies for clinical diagnosis and treatment.

Responses to Cytokines and Interferons that Depend upon JAKs and STATs

Many cytokines and all interferons activate members of a small family of kinases (the Janus kinases [JAKs]) and a slightly larger family of transcription factors (the signal transducers and activators of transcription [STATs]), which are essential components of pathways that induce the expression of specific sets of genes in susceptible cells. JAK-STAT pathways are required for many innate and acquired immune responses, and the activities of these pathways must be finely regulated to avoid major immune dysfunctions. Regulation is achieved through mechanisms that include the activation or induction of potent negative regulatory proteins, posttranslational modification of the STATs, and other modulatory effects that are cell-type specific. Mutations of JAKs and STATs can result in gains or losses of function and can predispose affected individuals to autoimmune disease, susceptibility to a variety of infections, or cancer. Here we review recent developments in the biochemistry, genetics, and biology of JAKs and STATs.

Argininosuccinate synthase 1 (ASS1): A marker of unclassified hepatocellular adenoma and high bleeding risk

Hepatocellular adenomas (HCAs) are rare benign tumors divided into three main subgroups defined by pathomolecular features, HNF1A (H-HCA), mutated β-catenin (b-HCA), and inflammatory (IHCA). In the case of unclassified HCAs (UHCAs), which are currently identified by default, a high risk of bleeding remains a clinical issue. The objective of this study was to explore UHCA proteome with the aim to identify specific biomarkers. Following dissection of the tumoral (T) and nontumoral (NT) tissue on formalin-fixed, paraffin-embedded HCA tissue sections using laser capture methodology, we performed mass spectrometry analysis to compare T and NT protein expression levels in H-HCA, IHCA, b-HCA, UHCA, and focal nodular hyperplasia. Using this methodology, we searched for proteins which are specifically deregulated in UHCA. We demonstrate that proteomic profiles allow for discriminating known HCA subtypes through identification of classical biomarkers in each HCA subgroup. We observed specific up-regulation of the arginine synthesis pathway associated with overexpression of argininosuccinate synthase (ASS1) and arginosuccinate lyase in UHCA. ASS1 immunohistochemistry identified all the UHCA, of which 64.7% presented clinical bleeding manifestations. Interestingly, we demonstrated that the significance of ASS1 was not restricted to UHCA, but also encompassed certain hemorrhagic cases in other HCA subtypes, particularly IHCA.

CONCLUSION

ASS1 + HCA combined with a typical hematoxylin and eosin stain aspect defined a new HCA subgroup at a high risk of bleeding. (Hepatology 2017;66:2016-2028).

Downregulation of pathways implicated in liver inflammation and tumorigenesis of glycogen storage disease type Ia mice receiving gene therapy

Glycogen storage disease type Ia (GSD-Ia) is characterized by impaired glucose homeostasis and long-term risks of hepatocellular adenoma (HCA) and carcinoma (HCC). We have shown that the non-tumor-bearing (NT), recombinant adeno-associated virus (rAAV) vector-treated GSD-Ia mice (AAV-NT mice) expressing a wide range (0.9-63%) of normal hepatic glucose-6-phosphatase-α activity maintain glucose homeostasis and display physiologic features mimicking animals living under calorie restriction (CR). We now show that in AAV-NT mice, the signaling pathways of the CR mediators, AMP-activated protein kinase (AMPK) and sirtuin-1 are activated. AMPK/sirtuin-1 inhibit the activity of STAT3 (signal transducer and activator of transcription 3) and NFκB (nuclear factor κB), the pro-inflammatory and cancer-promoting transcription factors. Sirtuin-1 also inhibits cancer metastasis via increasing the expression of E-cadherin, a tumor suppressor, and decreasing the expression of mesenchymal markers. Consistently, in AAV-NT mice, hepatic levels of active STAT3 and NFκB-p65 were reduced as were expression of mesenchymal markers, STAT3 targets, NFκB targets and β-catenin targets, all of which were consistent with the promotion of tumorigenesis. AAV-NT mice also expressed increased levels of E-cadherin and fibroblast growth factor 21 (FGF21), targets of sirtuin-1, and β-klotho, which can acts as a tumor suppressor. Importantly, treating AAV-NT mice with a sirtuin-1 inhibitor markedly reversed many of the observed anti-inflammatory/anti-tumorigenic signaling pathways. In summary, activation of hepatic AMPK/sirtuin-1 and FGF21/β-klotho signaling pathways combined with down-regulation of STAT3/NFκB-mediated inflammatory and tumorigenic signaling pathways can explain the absence of hepatic tumors in AAV-NT mice.

Recent development and gene therapy for glycogen storage disease type Ia

Glycogen storage disease type Ia (GSD-Ia) is an autosomal recessive metabolic disorder caused by a deficiency in glucose-6-phosphatase-α (G6Pase-α or G6PC) that is expressed primarily in the liver, kidney, and intestine. G6Pase-α catalyzes the hydrolysis of glucose-6-phosphate (G6P) to glucose and phosphate in the terminal step of gluconeogenesis and glycogenolysis, and is a key enzyme for endogenous glucose production. The active site of G6Pase-α is inside the endoplasmic reticulum (ER) lumen. For catalysis, the substrate G6P must be translocated from the cytoplasm into the ER lumen by a G6P transporter (G6PT). The functional coupling of G6Pase-α and G6PT maintains interprandial glucose homeostasis. Dietary therapies for GSD-Ia are available, but cannot prevent the long-term complication of hepatocellular adenoma that may undergo malignant transformation to hepatocellular carcinoma. Animal models of GSD-Ia are now available and are being exploited to both delineate the disease more precisely and develop new treatment approaches, including gene therapy.

A biallelic mutation in IL6ST encoding the GP130 co-receptor causes immunodeficiency and craniosynostosis

Multiple cytokines, including interleukin 6 (IL-6), IL-11, IL-27, oncostatin M (OSM), and leukemia inhibitory factor (LIF), signal via the common GP130 cytokine receptor subunit. In this study, we describe a patient with a homozygous mutation of IL6ST (encoding GP130 p.N404Y) who presented with recurrent infections, eczema, bronchiectasis, high IgE, eosinophilia, defective B cell memory, and an impaired acute-phase response, as well as skeletal abnormalities including craniosynostosis. The p.N404Y missense substitution is associated with loss of IL-6, IL-11, IL-27, and OSM signaling but a largely intact LIF response. This study identifies a novel immunodeficiency with phenotypic similarities to STAT3 hyper-IgE syndrome caused by loss of function of GP130.

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.

Hepatocellular Adenomas: Morphology and Genomics

Hepatocellular adenomas (HCAs) are rare benign tumors. This single entity has been split into 3 subtypes corresponding to specific mutations: HNF1α-inactivated HCA; inflammatory HCA related to different mutations, all leading to activation of STAT3 pathway; and β-catenin-activated HCA related to CTNNB1 mutations. The risk of malignant transformation depends on the level of β-catenin activation, reported mainly for exon 3, including S45. It is possible using specific immunohistochemical markers to identify the 3 different HCA subtypes and the level of β-catenin activation. Fewer than 10% of HCAs remain unclassified.

Glycogen storage disease type Ia mice with less than 2% of normal hepatic glucose-6-phosphatase-α activity restored are at risk of developing hepatic tumors

Glycogen storage disease type Ia (GSD-Ia), characterized by impaired glucose homeostasis and chronic risk of hepatocellular adenoma (HCA) and carcinoma (HCC), is caused by a deficiency in glucose-6-phosphatase-α (G6Pase-α or G6PC). We have previously shown that G6pc-/- mice receiving gene transfer mediated by rAAV-G6PC, a recombinant adeno-associated virus (rAAV) vector expressing G6Pase-α, and expressing 3-63% of normal hepatic G6Pase-α activity maintain glucose homeostasis and do not develop HCA/HCC. However, the threshold of hepatic G6Pase-α activity required to prevent tumor formation remained unknown. In this study, we constructed rAAV-co-G6PC, a rAAV vector expressing a codon-optimized (co) G6Pase-α and showed that rAAV-co-G6PC was more efficacious than rAAV-G6PC in directing hepatic G6Pase-α expression. Over an 88-week study, we showed that both rAAV-G6PC- and rAAV-co-G6PC-treated G6pc-/- mice expressing 3-33% of normal hepatic G6Pase-α activity (AAV mice) maintained glucose homeostasis, lacked HCA/HCC, and were protected against age-related obesity and insulin resistance. Of the eleven rAAV-G6PC/rAAV-co-G6PC-treated G6pc-/- mice harboring 0.9-2.4% of normal hepatic G6Pase-α activity (AAV-low mice), 3 expressing 0.9-1.3% of normal hepatic G6Pase-α activity developed HCA/HCC, while 8 did not (AAV-low-NT). Finally, we showed that the AAV-low-NT mice exhibited a phenotype indistinguishable from that of AAV mice expressing ≥3% of normal hepatic G6Pase-α activity. The results establish the threshold of hepatic G6Pase-α activity required to prevent HCA/HCC and show that GSD-Ia mice harboring <2% of normal hepatic G6Pase-α activity are at risk of tumor development.

Molecular Classification of Hepatocellular Adenoma Associates With Risk Factors, Bleeding, and Malignant Transformation

BACKGROUND & AIMS

Hepatocellular adenomas (HCAs) are benign liver tumors that can be assigned to molecular subtypes based on inactivating mutations in hepatocyte nuclear factor 1A, activating mutations in β-catenin, or activation of inflammatory signaling pathways. We aimed to update the classification system for HCA and associate the subtypes with disease risk factors and complications.

METHODS

We analyzed expression levels of 20 genes and sequenced exon regions of 8 genes (HNF1A, IL6ST, CTNNB1, FRK, STAT3, GNAS, JAK1, and TERT) in 607 samples of 533 HCAs from 411 patients, collected from 28 centers mainly in France from 2000 and 2014. We performed gene expression profile, RNA sequence, whole-exome and genome sequence, and immunohistochemical analyses of select samples. Molecular data were associated with risk factors, histopathology, bleeding, and malignant transformation.

RESULTS

Symptomatic bleeding occurred in 14% of the patients (85% of cases were female, median age, 38 years); 7% of the nodules were borderline between HCA and hepatocellular carcinoma, and 3% of patients developed hepatocellular carcinoma from HCA. Based on molecular features, we classified HCA into 8 subgroups. One new subgroup, composed of previously unclassified HCA, represented 4% of HCAs overall and was associated with obesity and bleeding. These tumors were characterized by activation of sonic hedgehog signaling, due to focal deletions that fuse the promoter of INHBE with GLI1. Analysis of genetic heterogeneity among multiple HCAs, from different patients, revealed a molecular subtype field effect; multiple tumors had different mutations that deregulated similar pathways. Specific molecular subtypes of HCA associated with various HCA risk factors, including imbalances in estrogen or androgen hormones. Specific molecular subgroup of HCA with β-catenin and sonic hedgehog activation associated with malignant transformation and bleeding, respectively.

CONCLUSIONS

Using sequencing and gene expression analyses, we identified a subgroup of HCA characterized by fusion of the INHBE and GLI1 genes and activation of sonic hedgehog pathway. Molecular subtypes of HCAs associated with different patients' risk factors for HCA, disease progression, and pathology features of tumors. This classification system might be used to select treatment strategies for patients with HCA.

Hepatocellular adenoma: Classification, variants and clinical relevance

Hepatocellular adenomas are benign tumors with two major complications, bleeding and malignant transformation. The overall narrative of hepatocellular adenoma has evolved over time. Solitary or multiple hepatocellular developing in the normal liver of women of child bearing age exposed to oral contraceptives still represents the most frequent clinical context, however, new associations are being recognized. Hepatocellular adenoma is discovered on a background of liver diseases such as non-alcoholic steatohepatitis, vascular diseases, and alcoholic cirrhosis. Hepatocellular adenoma is also reported in men, young or older adults, and even in infants. On the morpho-molecular side, the great leap forward was the discovery that hepatocellular adenoma was not a single entity and that at least 3 different subtypes exist, with specific underlying gene mutations. These mutations affect the HNF1A gene, several genes leading to JAK/STAT3 pathway activation and the CTNNB1 gene. All of them are associated with more or less specific histopathological characteristics and can be recognized using immunohistochemistry either with specific antibodies or with surrogate markers. Liver pathologists and radiologists are the key actors in the identification of the different subtypes of hepatocellular adenoma by the recognition of their specific morphological features. The major impact of the classification of hepatocellular adenoma is to identify subjects who are at higher risk of malignant transformation. With the development of new molecular technologies, there is hope for a better understanding of the natural history of the different subtypes, and, particularly for their mechanisms of malignant transformation.

STAT3 in the systemic inflammation of cancer cachexia

Weight loss is diagnostic of cachexia, a debilitating syndrome contributing mightily to morbidity and mortality in cancer. Most research has probed mechanisms leading to muscle atrophy and adipose wasting in cachexia; however cachexia is a truly systemic phenomenon. Presence of the tumor elicits an inflammatory response and profound metabolic derangements involving not only muscle and fat, but also the hypothalamus, liver, heart, blood, spleen and likely other organs. This global response is orchestrated in part through circulating cytokines that rise in conditions of cachexia. Exogenous Interleukin-6 (IL6) and related cytokines can induce most cachexia symptomatology, including muscle and fat wasting, the acute phase response and anemia, while IL-6 inhibition reduces muscle loss in cancer. Although mechanistic studies are ongoing, certain of these cachexia phenotypes have been causally linked to the cytokine-activated transcription factor, STAT3, including skeletal muscle wasting, cardiac dysfunction and hypothalamic inflammation. Correlative studies implicate STAT3 in fat wasting and the acute phase response in cancer cachexia. Parallel data in non-cancer models and disease states suggest both pathological and protective functions for STAT3 in other organs during cachexia. STAT3 also contributes to cancer cachexia through enhancing tumorigenesis, metastasis and immune suppression, particularly in tumors associated with high prevalence of cachexia. This review examines the evidence linking STAT3 to multi-organ manifestations of cachexia and the potential and perils for targeting STAT3 to reduce cachexia and prolong survival in cancer patients.

Preclinical Characterization of 3β-(N-Acetyl l-cysteine methyl ester)-2aβ,3-dihydrogaliellalactone (GPA512), a Prodrug of a Direct STAT3 Inhibitor for the Treatment of Prostate Cancer

The transcription factor STAT3 is a potential target for the treatment of castration-resistant prostate cancer. Galiellalactone (1), a direct inhibitor of STAT3, prevents the transcription of STAT3 regulated genes. In this study we characterized 6 (GPA512, Johansson , M. ; Sterner , O. Patent WO 2015/132396 A1, 2015 ), a prodrug of 1. In vitro studies showed that 6 is rapidly converted to 1 in plasma and is stable in a buffer solution. The pharmacokinetics of 6 following a single oral dose indicated that the prodrug was rapidly absorbed and converted to 1 with a tmax of 15 min. Oral administration of 6 in mice increased the plasma exposure of the active parent compound 20-fold compared to when 1 was dosed orally. 6 treated mice bearing DU145 xenograft tumors had significantly reduced tumor growth compared to untreated mice. The favorable druglike properties and safety profile of 6 warrant further studies of 6 for the treatment of castration-resistant prostate cancer.