STAT3 pathway in cancers: Past, present, and future

Deciphering the complex landscape of post-translational modifications on PKM2: Implications in head and neck cancer pathogenesis

In the vast landscape of human health, head and neck cancer (HNC) poses a significant health burden globally, necessitating the exploration of novel diagnostics and therapeutics. Metabolic alterations occurring within tumor microenvironment are crucial to understand the foundational cause of HNC. Post-translational modifications (PTMs) have recently emerged as a silent foe exerting a significantly heightened influence on various aspects of the biological processes associated with the onset and advancement of cancer, particularly in the context of HNC. There are numerous targets involved in HNC but recently, the enzyme pyruvate kinase M2 (PKM2) has come out as a hot target due to its involvement in glycolysis resulting in metabolic reprogramming of cancer cells. Various PTMs have been reported to affect the structure and function of PKM2 by modulating its activity. This review aims to investigate the impact of PTMs on the interaction between PKM2 and several signaling pathways and transcription factors in the context of HNC. These interactions possess significant ramification for cellular proliferation, apoptosis, angiogenesis and metastasis. This review primarily explores the role of PTMs influencing PKM2 and its involvement in tumor development. While acknowledging the significance of PKM2 interactions with other tumor regulators, the emphasis lies on dissecting PTM-related mechanisms rather than solely scrutinizing individual regulators. It lays the framework for the development of more sophisticated diagnostic tools and uncovers exciting possibilities for precision medicine essential for effectively addressing the complexity of this malignancy in a precise and focused manner.

Fucoxanthin induces human melanoma cytotoxicity by thwarting the JAK2/STAT3/BCL-xL signaling axis

Melanoma is the most lethal skin malignancy. Fucoxanthin is a marine carotenoid with significant anticancer activities. Intriguingly, Fucoxanthin's impact on human melanoma remains elusive. Signal Transducer and Activator of Transcription 3 (STAT3) represents a promising target in cancer therapy due to its persistent activation in various cancers, including melanoma. Herein, we revealed that Fucoxanthin is cytotoxic to human melanoma cell lines A2758 and A375 while showing limited cytotoxicity to normal human melanocytes. Apoptosis is a primary reason for Fucoxanthin's melanoma cytotoxicity, as the pan-caspase inhibitor z-VAD-fmk drastically abrogated Fucoxanthin-elicited clonogenicity blockage. Besides, Fucoxanthin downregulated tyrosine 705-phosphorylated STAT3 (p-STAT3 (Y705)), either inherently present in melanoma cells or inducible by interleukin 6 (IL-6) stimulation. Notably, ectopic expression of STAT3-C, a dominant-active STAT3 mutant, abolished Fucoxanthin-elicited melanoma cell apoptosis and clonogenicity inhibition, supporting the pivotal role of STAT3 blockage in Fucoxanthin's melanoma cytotoxicity. Moreover, Fucoxanthin lowered BCL-xL levels by blocking STAT3 activation, while ectopic BCL-xL expression rescued melanoma cells from Fucoxanthin-induced killing. Lastly, Fucoxanthin was found to diminish the levels of JAK2 with dual phosphorylation at tyrosine residues 1007 and 1008 in melanoma cells, suggesting that Fucoxanthin impairs STAT3 signaling by blocking JAK2 activation. Collectively, we present the first evidence that Fucoxanthin is cytotoxic selectively against human melanoma cells while sparing normal melanocytes. Mechanistically, Fucoxanthin targets the JAK2/STAT3/BCL-xL antiapoptotic axis to provoke melanoma cell death. This discovery implicates the potential application of Fucoxanthin as a chemopreventive or therapeutic strategy for melanoma management.

From immune equilibrium to tumor ecodynamics

Objectives

There is no theory to quantitatively describe the complex tumor ecosystem. At the same time, cancer immunotherapy is considered a revolution in oncology, but the methods used to describe tumors and the criteria used to evaluate efficacy are not keeping pace. The purpose of this study is to establish a new theory for quantitatively describing the tumor ecosystem, innovating the methods of tumor characterization, and establishing new efficacy evaluation criteria for cancer immunotherapy.

Methods

Based on the mathematization of immune equilibrium theory and the establishment of immunodynamics in a previous study, the method of reverse immunodynamics was used, namely, the immune braking force was regarded as the tumor ecological force and the immune force was regarded as the tumor ecological braking force, and the concept of momentum in physics was applied to the tumor ecosystem to establish a series of tumor ecodynamic equations. These equations were used to solve the fundamental and applied problems of the complex tumor ecosystem.

Results

A series of tumor ecodynamic equations were established. The tumor ecological momentum equations and their component factors could be used to distinguish disease progression, pseudoprogression, and hyperprogression in cancer immunotherapy. On this basis, the adjusted tumor momentum equations were established to achieve the equivalence of tumor activity (including immunosuppressive activity and metabolic activity) and tumor volume, which could be used to calculate individual disease remission rate and establish new efficacy evaluation criteria (ieRECIST) for immunotherapy of solid tumor based on tumor ecodynamics. At the same time, the concept of moving cube-to-force square ratio and its expression were proposed to calculate the area under the curve of tumor ecological braking force of blood required to achieve an individual disease remission rate when the adjusted tumor ecological momentum was known.

Conclusions

A new theory termed tumor ecodynamics emphasizing both tumor activity and tumor volume is established to solve a series of basic and applied problems in the complex tumor ecosystem. It can be predicted that the future will be the era of cancer immune ecotherapy that targets the entire tumor ecosystem.

Role and Mechanism of Growth Differentiation Factor 15 in Chronic Kidney Disease

GDF-15 is an essential member of the transforming growth factor-beta superfamily. Its functions mainly involve in tissue injury, inflammation, fibrosis, regulation of appetite and weight, development of tumor, and cardiovascular disease. GDF-15 is involved in various signaling pathways, such as MAPK pathway, PI3K/AKT pathway, STAT3 pathway, RET pathway, and SMAD pathway. In addition, several factors such as p53, ROS, and TNF-α participate the regulation of GDF-15. However, the specific mechanism of these factors regulating GDF-15 is still unclear and more research is needed to explore them. GDF-15 mainly improves the function of kidneys in CKD and plays an important role in the prediction of CKD progression and cardiovascular complications. In addition, the role of GDF-15 in the kidney may be related to the SMAD and MAPK pathways. However, the specific mechanism of these pathways remains unclear. Accordingly, more research on the specific mechanism of GDF-15 affecting kidney disease is needed in the future. In conclusion, GDF-15 may be a therapeutic target for kidney disease.

Major Facilitator Superfamily Domain Containing 12 Is Overexpressed in Lung Cancer and Exhibits an Oncogenic Role in Lung Adenocarcinoma Cells

Major facilitator superfamily domain containing 12 (MFSD12) regulates lysosomal cysteine import and promotes the proliferation and survival of melanoma cells. However, the expression and function of MFSD12 in other cancers, particularly in lung cancer, remain unclear. The expression of MFSD12 across various types of cancers and corresponding control tissues was examined using TIMER. MFSD12 expression in lung adenocarcinoma (LUAD) and its correlation with distinct clinicopathological features of LUAD patients were analyzed with UALCAN. The correlation between MFSD12 expression and survival of LUAD patients was assessed using the R package, survival, and the relationship between MFSD12 expression and immune infiltration status in LUAD was investigated using CIBERSORT. In addition, MFSD12 expression was knocked down in PC9 LUAD cells and their proliferation, capacity for expansion, cell cycle, apoptosis, and migration/invasion were evaluated through CCK-8 assays, colony formation assays, 7-AAD staining, Annexin V/PI staining, and Transwell assays, respectively. The stemness of these PC9 cells was determined through Western blotting, flow cytometry, and tumor sphere formation assays. MFSD12 mRNA levels were significantly elevated in multiple types of cancers, including LUAD. MFSD12 expression was also positively correlated with cancer stage, nodal metastasis, and infiltration of various immune cells in LUAD, and high MFSD12 levels predicted poor survival among LUAD patients. Knockdown of MFSD12 in PC9 cells resulted in decreased proliferation, attenuated colony formation capacity, cell cycle arrest, elevated apoptosis, impaired migration/invasion, and reduced stemness in PC9 cells. MFSD12 is an oncogene in LUAD.

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.

5-AZA Upregulates SOCS3 and PTPN6/SHP1, Inhibiting STAT3 and Potentiating the Effects of AG490 against Primary Effusion Lymphoma Cells

Epigenetic modifications, including aberrant DNA methylation occurring at the promoters of oncogenes and oncosuppressor genes and histone modifications, can contribute to carcinogenesis. Aberrant methylation mediated by histone methylatransferases, alongside histones, can affect methylation of proteins involved in the regulation of pro-survival pathways such as JAK/STAT and contribute to their activation. In this study, we used DNA or histone demethylating agents, 5-Azacytidine (5-AZA) or DS-3201 (valemetostat), respectively, to treat primary effusion lymphoma (PEL) cells, alone or in combination with AG490, a Signal transducer and activator of transcription 3 (STAT3) inhibitor. Cell viability was investigated by trypan blue assay and FACS analysis. The molecular changes induced by 5-AZA and/or AG490 treatments were investigated by Western blot analysis, while cytokine release by PEL cells treated by these drugs was evaluated by Luminex. Statistical analyses were performed with Graphpad Prism® software (version 9) and analyzed by Student's t test or a nonparametric one-way ANOVA test. The results obtained in this study suggest that 5-AZA upregulated molecules that inhibit STAT3 tyrosine phosphorylation, namely Suppressor of Cytokine Signaling 3 (SOCS3) and tyrosine-protein phosphatase non-receptor type (PTPN) 6/Src homology region 2 domain-containing phosphatase-1 (SHP-1), reducing STAT3 activation and downregulating several STAT3 pro-survival targets in PEL cells. As this lymphoma is highly dependent on the constitutive activation of STAT3, 5-AZA impaired PEL cell survival, and when used in combination with AG490 JAK2/STAT3 inhibitor, it potentiated its cytotoxic effect. Differently from 5-AZA, the inhibition of the EZH1/2 histone methyltransferase by DS-3201, reported to contribute to STAT3 activation in other cancers, slightly affected STAT3 phosphorylation or survival in PEL cells, either alone or in combination with AG490. This study suggests that 5-AZA, by upregulating the expression level of SOCS3 and PTPN6/SHP1, reduced STAT3 activation and improved the outcome of treatment targeting this transcription factor in PEL cells.

Molecular heterogeneity in histomorphologic subtypes of lung adeno carcinoma represents a challenge for treatment decision

Lung cancer is the leading cause in cancer related death, with non-small cell lung cancer (NSCLC) being the most frequent subtype. The importance of NSCLC is reflected by the various targeted therapy options especially for NSCLC adenocarcinomas (lung adeno carcinoma (LUAD)) as well as a set of options for immune therapies. However, despite these therapy advances, the majority of patients do not show a long-term response to either targeted therapy or immune checkpoint inhibition. One reason for treatment failure appears to be the NSCLC tumor heterogeneity. NSCLC heterogeneity might lead to an insufficient molecular characterization of a given sample due to the limited tumor material used for pathological assessment as the majority of analyses is performed on small biopsies. To get a more detailed insight into the tumor heterogeneity of NSCLC LUAD, especially in the light of its different histomorphological growth patterns, we analysed isolated NSCLC growth pattern areas and the corresponding entire tumor samples of a cohort of 31 NSLCS LUAD patients and compared their mutational landscape and their expression profiles. While significant differences of complex biomarkers, like tumor mutational burden (TMB) or microsatellite instability (MSI), were not detected between the five growth patterns -lepidic, papillary, micropapillary, acinar, and solid- we observed various subclonal mutations and copy number variants. Moreover, RNASeq analysis revealed growth pattern specific expression profiles affecting cellular processes like apoptosis, metastasis and proliferation. Taken together, our data provide novel insights into the tumor heterogeneity of LUAD required to overcome tumor heterogeneity related therapy resistance.

Multifaceted roles for STAT3 in gammaherpesvirus latency revealed through in vivo B cell knockout models

Cancers associated with the oncogenic gammaherpesviruses, Epstein-Barr virus and Kaposi sarcoma herpesvirus, are notable for their constitutive activation of the transcription factor signal transducer and activator of transcription 3 (STAT3). To better understand the role of STAT3 during gammaherpesvirus latency and the B cell response to infection, we used the model pathogen murine gammaherpesvirus 68 (MHV68). Genetic deletion of STAT3 in B cells of CD19cre/+Stat3f/f mice reduced peak MHV68 latency approximately sevenfold. However, infected CD19cre/+Stat3f/f mice exhibited disordered germinal centers and heightened virus-specific CD8 T cell responses compared to wild-type (WT) littermates. To circumvent the systemic immune alterations observed in the B cell-STAT3 knockout mice and more directly evaluate intrinsic roles for STAT3, we generated mixed bone marrow chimeric mice consisting of WT and STAT3 knockout B cells. We discovered a dramatic reduction in latency in STAT3 knockout B cells compared to their WT B cell counterparts in the same lymphoid organ. RNA sequencing of sorted germinal center B cells revealed that MHV68 infection shifts the gene signature toward proliferation and away from type I and type II IFN responses. Loss of STAT3 largely reversed the virus-driven transcriptional shift without impacting the viral gene expression program. STAT3 promoted B cell processes of the germinal center, including IL-21-stimulated downregulation of surface CD23 on B cells infected with MHV68 or EBV. Together, our data provide mechanistic insights into the role of STAT3 as a latency determinant in B cells for oncogenic gammaherpesviruses.IMPORTANCEThere are no directed therapies to the latency program of the human gammaherpesviruses, Epstein-Barr virus and Kaposi sarcoma herpesvirus. Activated host factor signal transducer and activator of transcription 3 (STAT3) is a hallmark of cancers caused by these viruses. We applied the murine gammaherpesvirus pathogen system to explore STAT3 function upon primary B cell infection in the host. Since STAT3 deletion in all CD19+ B cells of infected mice led to altered B and T cell responses, we generated chimeric mice with both normal and STAT3-deleted B cells. B cells lacking STAT3 failed to support virus latency compared to normal B cells from the same infected animal. Loss of STAT3 impaired B cell proliferation and differentiation and led to a striking upregulation of interferon-stimulated genes. These findings expand our understanding of STAT3-dependent processes that are key to its function as a pro-viral latency determinant for oncogenic gammaherpesviruses in B cells and may provide novel therapeutic targets.

Leonurine ameliorates the STAT3 pathway through the upregulation of SHP-1 to retard the growth of hepatocellular carcinoma cells

Signal transducer and activator of transcription 3 (STAT3) is a transcription factor that directs the transcription of genes involved in the promotion of cell survival and proliferation, inflammation, angiogenesis, invasion, and migration. Overactivation of STAT3 is often witnessed in human cancers, thereby making it a good target in oncology. Herein the efficacy of Leonurine (Leo), a bioactive alkaloid present in Herba leonuri, was investigated for its STAT3-inhibitory potential in hepatocellular carcinoma (HCC) cells. Leo downregulated the persistent as well as IL-6-driven activation of STAT3. Leo abrogated the nuclear localization and DNA interacting ability of STAT3. Leo was also found to impart STAT3 inhibition by mitigating the activation of upstream kinases such as JAK1, JAK2, and Src both in constitutive and IL-6 inducible systems. Leo curbed the STAT3-driven luciferase gene expression and the depletion of STAT3 resulted in the reduced responsiveness of HCC cells to Leo. Pervanadate exposure counteracted Leo-induced STAT3 inhibition suggesting the involvement of a protein tyrosine phosphatase. SHP-1 was significantly elevated upon Leo exposure whereas the depletion of SHP-1 was found to revert the effect of Leo on STAT3. Leo induced apoptosis and also significantly potentiated the cytotoxic effect of paclitaxel, doxorubicin, and sorafenib. Leo was found to be non-toxic up to the dose of 10 mg/kg in NCr nude mice. In conclusion, Leo was demonstrated to induce cytotoxicity in HCC cells by mitigating the persistent of activation of STAT3 pathway.

Exploring Novel Frontiers: Leveraging STAT3 Signaling for Advanced Cancer Therapeutics

Signal Transducer and Activator of Transcription 3 (STAT3) plays a significant role in diverse physiologic processes, including cell proliferation, differentiation, angiogenesis, and survival. STAT3 activation via phosphorylation of tyrosine and serine residues is a complex and tightly regulated process initiated by upstream signaling pathways with ligand binding to receptor and non-receptor-linked kinases. Through downstream deregulation of target genes, aberrations in STAT3 activation are implicated in tumorigenesis, metastasis, and recurrence in multiple cancers. While there have been extensive efforts to develop direct and indirect STAT3 inhibitors using novel drugs as a therapeutic strategy, direct clinical application remains in evolution. In this review, we outline the mechanisms of STAT3 activation, the resulting downstream effects in physiologic and malignant settings, and therapeutic strategies for targeting STAT3. We also summarize the pre-clinical and clinical evidence of novel drug therapies targeting STAT3 and discuss the challenges of establishing their therapeutic efficacy in the current clinical landscape.

Structural determinants of mitochondrial STAT3 targeting and function

Signal transducer and activator of transcription (STAT) 3 has been found within mitochondria in addition to its canonical role of shuttling between cytoplasm and nucleus during cytokine signaling. Mitochondrial STAT3 has been implicated in modulation of cellular metabolism, largely through effects on the respiratory electron transport chain. However, the structural requirements underlying mitochondrial targeting and function have remained unclear. Here, we show that mitochondrial STAT3 partitions between mitochondrial compartments defined by differential detergent solubility, suggesting that mitochondrial STAT3 is membrane associated. The majority of STAT3 was found in an SDS soluble fraction copurifying with respiratory chain proteins, including numerous components of the complex I NADH dehydrogenase, while a minor component was found with proteins of the mitochondrial translation machinery. Mitochondrial targeting of STAT3 required the amino-terminal domain, and an internal linker domain motif also directed mitochondrial translocation. However, neither the phosphorylation of serine 727 nor the presence of mitochondrial DNA was required for the mitochondrial localization of STAT3. Two cysteine residues in the STAT3 SH2 domain, which have been previously suggested to be targets for protein palmitoylation, were also not required for mitochondrial translocation, but were required for its function as an enhancer of complex I activity. These structural determinants of STAT3 mitochondrial targeting and function provide potential therapeutic targets for disrupting the activity of mitochondrial STAT3 in diseases such as cancer.

Cancer metastasis under the magnifying glass of epigenetics and epitranscriptomics

Most of the cancer-associated mortality and morbidity can be attributed to metastasis. The role of epigenetic and epitranscriptomic alterations in cancer origin and progression has been extensively demonstrated during the last years. Both regulations share similar mechanisms driven by DNA or RNA modifiers, namely writers, readers, and erasers; enzymes responsible of respectively introducing, recognizing, or removing the epigenetic or epitranscriptomic modifications. Epigenetic regulation is achieved by DNA methylation, histone modifications, non-coding RNAs, chromatin accessibility, and enhancer reprogramming. In parallel, regulation at RNA level, named epitranscriptomic, is driven by a wide diversity of chemical modifications in mostly all RNA molecules. These two-layer regulatory mechanisms are finely controlled in normal tissue, and dysregulations are associated with every hallmark of human cancer. In this review, we provide an overview of the current state of knowledge regarding epigenetic and epitranscriptomic alterations governing tumor metastasis, and compare pathways regulated at DNA or RNA levels to shed light on a possible epi-crosstalk in cancer metastasis. A deeper understanding on these mechanisms could have important clinical implications for the prevention of advanced malignancies and the management of the disseminated diseases. Additionally, as these epi-alterations can potentially be reversed by small molecules or inhibitors against epi-modifiers, novel therapeutic alternatives could be envisioned.

Prevention of STAT3-related pathway in SK-N-SH cells by natural product astaxanthin

PURPOSE

Neuroblastoma (NB) is the most common solid malignancy in children. Despite current intensive treatment, the long-term event-free survival rate is less than 50% in these patients. Thus, patients with NB urgently need more valid treatment strategies. Previous research has shown that STAT3 may be an effective target in high-risk NB patients. However, there are no effective inhibitors in clinical evaluation with low toxicity and few side effects. Astaxanthin is a safe and natural anticancer product. In this study, we investigated whether astaxanthin could exert antitumor effects in the SK-N-SH neuroblastoma cancer cell line.

METHOD

MTT and colony formation assays were used to determine the effect of astaxanthin on the proliferation and colony formation of SK-N-SH cells. Flow cytometry assays were used to detect the apoptosis of SK-N-SH cells. The migration and invasion ability of SK-N-SH cells were detected by migration and invasion assays. Western blot and RT-PCR were used to detect the protein and mRNA levels. Animal experiments were carried out and cell apoptosis in tissues were assessed using a TUNEL assay.

RESULT

We confirmed that astaxanthin repressed proliferation, clone formation ability, migration and invasion and induced apoptosis in SK-N-SH cells through the STAT3 pathway. Furthermore, the highest inhibitory effect was observed when astaxanthin was combined with si-STAT3. The reason for this may be that the combination of astaxanthin and si-STAT3 can lower STAT3 expression further than astaxanthin or si-STAT3 alone.

CONCLUSION

Astaxanthin can exert anti-tumor effect on SK-N-SH cells. The inhibitory effect was the higher when astaxanthin was combined with si-STAT3.

2022 Cannon lecture: an ode to signal transduction: how the growth hormone pathway revealed insight into height, malignancy, and obesity

Walter Cannon was a highly regarded American neurologist and physiologist with extremely broad interests. In the tradition of Cannon and his broad interests, we discuss our laboratory's multifaceted work in signal transduction over the past 40+ years. We show how our questioning of how growth hormone (GH) in the blood communicates with cells throughout the body to promote body growth and regulate body metabolism led to insight into not only body height but also important regulators of malignancy and body weight. Highlights include finding that 1) A critical initiating step in GH signal transduction is GH activating the GH receptor-associated tyrosine kinase JAK2; 2) GH activation of JAK2 leads to activation of a number of signaling proteins, including STAT transcription factors; 3) JAK2 is autophosphorylated on multiple tyrosines that regulate the activity of JAK2 and recruit signaling proteins to GH/GH receptor/JAK2 complexes; 4) Constitutively activated STAT proteins are associated with cancer; 5) GH activation of JAK2 recruits the adapter protein SH2B1 to GH/GH receptor/JAK2 complexes where it facilitates GH regulation of the actin cytoskeleton and motility; and 6) SH2B1 is recruited to other receptors in the brain, where it enhances satiety, most likely in part by regulating leptin action and neuronal connections of appetite-regulating neurons. These findings have led to increased understanding of how GH functions, as well as therapeutic interventions for certain cancer and obese individuals, thereby reinforcing the great importance of supporting basic research since one never knows ahead of time what important insight it can provide.

Solamargine induces apoptosis of human renal carcinoma cells via downregulating phosphorylated STAT3 expression

Solamargine (SM), an active compound derived from Solanum nigrum, triggers apoptosis and inhibits the metastatic and oxidative activities of various types of tumor cells. However, the effect of SM on human renal carcinoma cells remains unknown. In the present study, the molecular mechanisms underlying the antitumor effects of SM on ACHN and 786-O cells were elucidated. Specifically, MTT and colony formation assays were conducted to evaluate the impact of SM treatment on the proliferation of ACHN and 786-O cells, and flow cytometry was conducted to determine the influence of SM on the apoptosis rates of these cells. In addition, the expression of target proteins was determined by western blotting. The results revealed that SM not only inhibited cell viability but also promoted the apoptosis of ACHN and 786-O cells in a time- and dose-dependent manner. Moreover, treatment of ACHN and 786-O cells with SM significantly enhanced the caspase-3, caspase-8 and caspase-9 activities. Furthermore, SM downregulated the expression of phosphorylated signal transducer and activator of transcription-3 (p-STAT3) and Bcl-2 but increased the expression of cleaved caspase-3, -8, -9 and Bax. BAY2353, a p-STAT3 inhibitor, inhibited the viability of ACHN and 786-O cells, increased the expression of cleaved caspase-9 and Bax and decreased the expression of p-STAT3 and Bcl-2. Further experiments demonstrated that SM inhibited tumor growth in xenograft nude mice without causing specific toxicity to the major organs. Collectively, these findings indicated that SM not only inhibited the viability but also promoted the apoptosis of ACHN and 786-O cells, through a mechanism involving downregulation of p-STAT3 expression.

Epstein-Barr virus infectious particles initiate B cell transformation and modulate cytokine response

IMPORTANCE

The Epstein-Barr virus efficiently infects and transforms B lymphocytes. During this process, infectious viral particles transport the viral genome to the nucleus of target cells. We show here that these complex viral structures serve additional crucial roles by activating transcription of the transforming genes encoded by the virus. We show that components of the infectious particle sequentially activate proinflammatory B lymphocyte signaling pathways that, in turn, activate viral gene expression but also cause cytokine release. However, virus infection activates expression of ZFP36L1, an RNA-binding stress protein that limits the length and the intensity of the cytokine response. Thus, the infectious particles can activate viral gene expression and initiate cellular transformation at the price of a limited immune response.

Potential roles of lncRNA MALAT1-miRNA interactions in ocular diseases

Long non-coding RNAs (lncRNAs) are non-protein coding transcripts that are longer than 200 nucleotides in length. LncRNAs are implicated in gene expression at the transcriptional, translational, and epigenetic levels, and thereby impact different cellular processes including cell proliferation, migration, apoptosis, angiogenesis, and immune response. In recent years, numerous studies have demonstrated the significant contribution of lncRNAs to the pathogenesis and progression of various diseases, such as stroke, heart disease, and cancer. Further investigations have shown that lncRNAs have altered expression patterns in ocular tissues and cell lines during pathological conditions. The pathogenesis of various ocular diseases, including glaucoma, cataract, corneal diseases, proliferative vitreoretinopathy, diabetic retinopathy, and retinoblastoma, is influenced by the involvement of specific lncRNAs which play a critical role in the development and progression of these diseases. Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is a well-researched lncRNA in the context of ocular diseases, which has been shown to exert its biological effects through several signaling pathways and downstream targets. The present review provides a comprehensive summary of the molecular mechanisms underlying the biological functions and roles of MALAT1 in ocular diseases.

The impact of cellular elements of TME on melanoma biology and its sensitivity to EGFR and MET targeted therapy

Microenvironment of the melanoma consists of cellular elements like fibroblasts, adipocytes, and keratinocytes as well as extracellular matrix and physicochemical conditions. In our previous research, we have established that melanoma influences strongly above mentioned cells present in the tumor niche and recruits them to support cancer progression. In this work, we evaluated the impact of cancer-associated cells, namely fibroblasts (CAFs), adipocytes (CAAs), and keratinocytes (CAKs) on melanoma proliferation, signaling pathways activation, metabolism as well as the effectiveness of used anti-cancer therapy. Obtained results indicated elevated phosphorylation of STAT3, upregulated GLUT1 and GLUT3 as well as downregulated of MCT-1 expression level in melanoma cells under the influence of all examined cells present in the tumor niche. The proliferation of melanoma cells was increased after co-culture with CAFs and CAKs, while epithelial-mesenchymal transition markers' expression level was raised in the presence of CAFs and CAAs. The level of perilipin 2 and lipid content was elevated in melanoma cells under the influence of CAAs. Moreover, increased expression of CYP1A1, gene encoding drug metabolizing protein, in melanoma cells co-cultured with CAFs and CAKs prompted us to verify the effectiveness of the previously proposed by us anti-melanoma therapy based on combination of EGFR and MET inhibitors. Obtained results indicate that the designed therapy is still efficient, even if the fibroblasts, adipocytes, and keratinocytes, are present in the melanoma vicinity.

Blockade of the SRC/STAT3/BCL-2 Signaling Axis Sustains the Cytotoxicity in Human Colorectal Cancer Cell Lines Induced by Dehydroxyhispolon Methyl Ether

Colorectal cancer (CRC) is the third most prevalent human cancer globally. 5-Fluorouracil (5-FU)-based systemic chemotherapy is the primary strategy for advanced CRC treatment, yet is limited by poor response rate. Deregulated activation of signal transducer and activator of transcription 3 (STAT3) is fundamental to driving CRC malignant transformation and a poor prognostic marker for CRC, underscoring STAT3 as a promising CRC drug target. Dehydroxyhispolon methyl ether (DHME) is an analog of Hispolon, an anticancer polyphenol abundant in the medicinal mushroom Phellinus linteus. Previously, we have established DHME's cytotoxic effect on human CRC cell lines by eliciting apoptosis through the blockade of WNT/β-catenin signaling, a preeminent CRC oncogenic pathway. Herein, we unraveled that compared with 5-FU, DHME is a more potent killer of CRC cells while being much less toxic to normal colon epithelial cells. DHME suppressed both constitutive and interleukin 6 (IL-6)-induced STAT3 activation represented by tyrosine 705 phosphorylation of STAT3 (p-STAT3 (Y705)); notably, DHME-induced CRC apoptosis and clonogenicity limitation were abrogated by ectopic expression of STAT3-C, a dominant-active STAT3 mutant. Additionally, we proved that BCL-2 downregulation caused by DHME-mediated STAT3 blockage is responsible for DHME-induced CRC cell apoptosis. Lastly, DHME inhibited SRC activation, and v-src overexpression restored p-STAT3 (Y705) levels along with lowering the levels of apoptosis in DHME-treated CRC cells. We conclude DHME provokes CRC cell apoptosis by blocking the SRC/STAT3/BCL-2 axis besides thwarting WNT/β-catenin signaling. The notion that DHME targets two fundamental CRC signaling pathways underpins the potential of DHME as a CRC chemotherapy agent.

Antimetastatic activity of seongsanamide B in γ-irradiated human lung cancer

Lung cancer, which has a high incidence and mortality rates, often metastasizes and exhibits resistance to radiation therapy. Seongsanamide B has conformational features that suggest it has therapeutic potential; however, its antitumor activity has not yet been reported. We evaluated the possibility of seongsanamide B as a radiation therapy efficiency enhancer to suppress γ-irradiation-induced metastasis in non-small cell lung cancer. Seongsanamide B suppressed non-small cell lung cancer cell migration and invasion caused by γ-irradiation. Furthermore, it suppressed γ-irradiation-induced upregulation of Bcl-XL and its downstream signaling molecules, such as superoxide dismutase 2 (SOD2) and phosphorylated Src, by blocking the nuclear translocation of phosphorylated STAT3. Additionally, seongsanamide B markedly modulated the γ-irradiation-induced upregulation of E-cadherin and vimentin. Consistent with the results obtained in vitro, while seongsanamide B did not affect xenograft tumor growth, it significantly suppressed γ-irradiation-induced metastasis by inhibiting Bcl-XL/SOD2/phosphorylated-Src expression and modulating E-cadherin and vimentin expression in a mouse model. Thus, seongsanamide B may demonstrate potential applicability as a radiation therapy efficiency enhancer for lung cancer treatment.

Nuclear translocation of thioredoxin-1 promotes colorectal cancer development via modulation of the IL-6/STAT3 signaling axis through interaction with STAT3

Background: Thioredoxin 1 (Trx-1) is a small redox protein predominantly localized in the cytoplasm. Its expression is increased in several cancers, including colorectal cancer (CRC). However, the function of Trx-1 translocation to the nucleus in cancer is not clear. In this study, we investigated the role of Trx-1 nuclear translocation in development of CRC. Methods: Expression of Trx-1 and STAT3 was analyzed by Western blot and immunofluorescence. Endogenous interaction of Trx-1, STAT3, and karyopherin α1 in CRC cells was analyzed by co-immunoprecipitation. Trx-1 and pSTAT3 nuclear staining in human CRC tissues was analyzed by immunohistochemistry. A mouse model of AOM/DSS induced colitis-associated cancer (CAC) was utilized to investigate the antitumor effect of PX-12, a Trx-1 inhibitor. A knockin mouse with the Txn1(KK81-82EE) mutation was generated via CRISPR/Cas9, and CAC was induced in knockin and wild-type mice. Results: Nuclear translocation of Trx-1 was induced by IL-6, and inhibition of this translocation reversed IL-6-induced epithelial-to-mesenchymal transition, invasion and metastasis. Karyopherin α1 was found to specifically mediate IL-6-induced translocation of the Trx-1-pSTAT3 complex into the nucleus. Nuclear Trx-1 expression was closely correlated with lymph node metastasis and distant metastasis in human CRC. In addition, nuclear staining of Trx-1 showed significant positive correlation with nuclear staining of pSTAT3 in human CRC tissues. PX-12, an inhibitor of Trx-1, significantly impaired the activation of STAT3 and suppressed the development of AOM/DSS-induced CAC in mice. Moreover, AOM/DSS-induced nuclear Trx-1 expression was suppressed in Txn1(KK81-82EE) mice, which inhibited STAT3 activation and cancer progression. Conclusions: These results provide new insights into the mechanisms of STAT3 activation triggered by IL-6 and identify nuclear translocation of Trx-1 as a potential therapeutic target for the treatment of CRC and CAC.

Evaluation of premetastatic changes in lymph nodes(pN0) of oral tongue tumour: A prospective observational Study

Background: Tongue tumors show intra and inter-tumoral heterogenicity with high incidence, relapse and mortality rates necessitating further research.  Recurrence/metastasis that occurs  after surgical resection of primary cancer is often the reason for poor survival in these patients.  Lymph nodes are the most common site of metastasis in tongue tumors. Therefore, premetastatic molecular changes can be best evaluated in lymph nodes which may epitomize the earliest events in the metastasis cascades. The presence of circulating tumor cells(CTCs) in the absence of nodal disease (N0) may represent tumor aggressiveness, suggesting an immune escape which may have high metastatic potential. This trial  was developed  to investigate the earliest pre-metastatic changes which may regulate tumor dormancy and predict metastasis. A better understanding of organotropism or pre-metastatic changes can help in theragnostic, thereby  preventing the outbreak of overt metastasis.  Methods: A single-institutional prospective observational cohort study. This trial will be conducted at a tertiary care Centre (Amrita Institute of Medical Sciences Kochi).  Eligible patients will be enrolled after obtaining informed consent. The dissected lymph nodes will  be subjected to histopathological and immunohistochemical analyses for premetastatic niche (PMN) formation. In addition, circulating tumor cells will be evaluated before treatment and 6 months after treatment. The patients will be followed  up for a period of two years to correlate the findings with the recurrence-free survival. Expected results:  The pre-metastatic changes, if detected will  be  a predictive biomarker. It may help to define future drug targets for metastasis chemoprevention   . CTCs may  define the tumor aggressiveness ,there by  prognostication  and helps in better disease management. Ethics and dissemination: The study has received the following approval: Ethics Committee of Amrita School of Medicine (ECASM-AIMS-2022-048).Trial Registered Prospectively( CTRI/2022/03/041256 ) on 22/03/2022 under Clinical Trial Registry of India.

Sertindole, an Antipsychotic Drug, Curbs the STAT3/BCL-xL Axis to Elicit Human Bladder Cancer Cell Apoptosis In Vitro

Bladder cancer is the leading urinary tract malignancy. Epidemiological evidence has linked lower cancer incidence in schizophrenia patients to long-term medication, highlighting the anticancer potential of antipsychotics. Sertindole is an atypical antipsychotic agent with reported anticancer action on breast and gastric cancers. Yet, sertindole's effect on bladder cancer remains unaddressed. We herein present the first evidence of sertindole's antiproliferative effect and mechanisms of action on human bladder cancer cells. Sertindole was cytotoxic against bladder cancer cells while less cytotoxic to normal urothelial cells. Apoptosis was a primary cause of sertindole's cytotoxicity, as the pan-caspase inhibitor z-VAD-fmk rescued cells from sertindole-induced killing. Mechanistically, sertindole inhibited the activation of signal transducer and activator of transcription 3 (STAT3), an oncogenic driver of bladder cancer, as sertindole lowered the levels of tyrosine 705-phosphorylated STAT3 along with that of STAT3's target gene BCL-xL. Notably, ectopic expression of the dominant-active STAT3 mutant impaired sertindole-induced apoptosis in addition to restoring BCL-xL expression. Moreover, bladder cancer cells overexpressing BCL-xL were refractory to sertindole's proapoptotic action, arguing that sertindole represses STAT3 to downregulate BCL-xL, culminating in the induction of apoptosis. Overall, the current study indicated sertindole exerts bladder cancer cytotoxicity by provoking apoptosis through targeted inhibition of the antiapoptotic STAT3/BCL-xL signaling axis. These findings implicate the potential to repurpose sertindole as a therapeutic strategy for bladder cancer.

Venetoclax durable response in adult relapsed/refractory Philadelphia-negative acute lymphoblastic leukemia with JAK/STAT pathway alterations

High-risk relapsed/refractory adult Philadelphia-negative (Ph-) B-cell acute lymphoblastic leukemia (B-ALL) is a great challenge due to limited possibilities to achieve and maintain a complete response. This also applies to cases with extramedullary (EM) involvement that have poor outcomes and no accepted standard therapeutic approaches. The incidence of EM localization in relapsed/refractory B-ALL is poorly investigated: data on patients treated with blinatumomab reported a 40% rate. Some responses were reported in EM patients with relapsed/refractory B-ALL treated with inotuzumab ozogamicin or CAR-T. However, molecular mechanisms of response or refractoriness are usually investigated neither at the medullary nor at EM sites. In the complex scenario of pluri-relapsed/refractory B-ALL patients, new target therapies are needed. Our analysis started with the case of an adult pluri-relapsed Ph- B-ALL patient, poorly sensitive to inotuzumab ozogamicin, donor lymphocyte infusions, and blinatumomab in EM disease, who achieved a durable/complete response after treatment with the BCL2-inhibitor venetoclax. The molecular characterization of medullary and EM samples revealed a tyrosine kinase domain JAK1 mutation in the bone marrow and EM samples at relapse. By comparing the expression level of BCL2- and JAK/STAT pathway-related genes between the patient samples, 136 adult JAK1 ^wt B-ALL, and 15 healthy controls, we identified differentially expressed genes, including LIFR, MTOR, SOCS1/2, and BCL2/BCL2L1, that are variably modulated at diverse time points and might explain the prolonged response to venetoclax (particularly in the EM site, which was only partially affected by previous therapies). Our results suggest that the deep molecular characterization of both medullary and EM samples is fundamental to identifying effective and personalized targeted therapies.

A Novel Ageladine A Derivative Acts as a STAT3 Inhibitor and Exhibits Potential Antitumor Effects

The Janus kinase/signal transducer and activator of the transcription 3 (JAK/STAT3) signaling pathway controls multiple biological processes, including cell survival, proliferation, and differentiation. Abnormally activated STAT3 signaling promotes tumor cell growth, proliferation, and survival, as well as tumor invasion, angiogenesis, and immunosuppression. Hence, JAK/STAT3 signaling has been considered a promising target for antitumor therapy. In this study, a number of ageladine A derivative compounds were synthesized. The most effective of these was found to be compound 25. Our results indicated that compound 25 had the greatest inhibitory effect on the STAT3 luciferase gene reporter. Molecular docking results showed that compound 25 could dock into the STAT3 SH2 structural domain. Western blot assays demonstrated that compound 25 selectively inhibited the phosphorylation of STAT3 on the Tyr705 residue, thereby reducing STAT3 downstream gene expression without affecting the expression of the upstream proteins, p-STAT1 and p-STAT5. Compound 25 also suppressed the proliferation and migration of A549 and DU145 cells. Finally, in vivo research revealed that 10 mg/kg of compound 25 effectively inhibited the growth of A549 xenograft tumors with persistent STAT3 activation without causing significant weight loss. These results clearly indicate that compound 25 could be a potential antitumor agent by inhibiting STAT3 activation.

Evaluation of Signal Transducer and Activator of Transcription 3 (STAT-3) Protein Expression in Non-Hodgkin Lymphoma Cases in Hospital USM

BACKGROUND

Evolving targeted therapy on Janus Associated Kinase-Signal Transducer and Activator of Transcription (JAK-STAT) signaling pathway, especially pertaining to STAT-3 protein in non-Hodgkin lymphoma (NHL), provides new treatment strategies. STAT-3 protein also relates to the prognostication of NHL. Hence, we aimed to evaluate the expression of STAT-3 protein in NHL cases diagnosed in Hospital Universiti Sains Malaysia (USM).

METHODS

A retrospective cross sectional study using formalin fixed paraffin embedded (FFPE) tissue blocks of 95 NHL cases were obtained. STAT-3 immunostaining was performed and evaluated. The proportion and association between the expression of STAT-3 protein with subtypes of NHL were statistically analyzed.

RESULTS

The majority of the cases (78.9%) had positive STAT-3 protein expression. 64.2% were among aggressive B cell NHL, whilst 20.0% of them were diffuse large B cell lymphoma, a non-germinal center B subtype (DLBCL-NGCB). There is also an association between STAT-3 protein expression with DLBCL subtypes (p = 0.046).

CONCLUSION

Our study demonstrated a remarkable expression of STAT-3 protein in NHL, in which DLBCL subtypes had significant association. A larger scale study with a combination of JAK protein evaluation should be undertaken in the future.

Pharmacological anti-tumor effects of natural Chamaecyparis obtusa (siebold & zucc.) endl. Leaf extracts on breast cancer

ETHNOPHARMACOLOGICAL RELEVANCE

Chamaecyparis obtusa (C. obtusa, cypress species) is a plant that grows mainly in the temperate Northern Hemisphere and has long been used as a traditional anti-inflammatory treatment in East Asia. C. obtusa contains phytoncides, flavonoids, and terpenes, which have excellent anti-cancer effects and have been reported to prevent the progression of various cancers. However, the detailed mechanisms underlying the anti-cancer effects of C. obtusa extracts are unknown.

AIM OF THE STUDY

We sought to confirm the anti-cancer effects of C. obtusa leaf extracts and to reveal the mechanism of action, with the possibility of its application in the treatment or prevention of cancer.

MATERIAL &METHODS

The cytotoxicity of C. obtusa leaf extracts was confirmed using an MTT assay. Intracellular changes in protein levels were measured by immunoblotting, and mRNA levels were measured with qRT-PCR. Wound healing assay and transwell migration assay were used to evaluate the metastatic potential of breast cancer cells. The extract-induced apoptosis was observed using IncuCyte Annexin V Red staining analysis. A syngeneic breast cancer mouse model was established by injecting 4T1-Luc mouse breast cancer cells into the fat pad of female BALB/c mice, and the extract was administered orally. Luciferin solution was injected intraperitoneally to assess primary tumor development and metastasis by bioluminescence.

RESULTS

C. obtusa leaf extracts were extracted with boiling water, 70% EtOH, and 99% EtOH. Among the extracts, the 99% EtOH extract of C. obtusa leaf (CO99EL) most clearly inhibited the tyrosine phosphorylation of Signal Transducer and Activator of Transcription 3 (pY-STAT3) in MDA-MB-231 breast cancer cells at a concentration of 25 and 50 μg/mL. In addition, CO99EL strongly inhibited not only endogenous pY-STAT3 levels but also IL-6-induced STAT3 activation in various types of cancer cells, including breast cancer. CO99EL inhibited metastatic potential by downregulating the expression of N-cadherin, fibronectin, TWIST, MMP2, and MMP9 in MDA-MB-231 breast cancer cells. CO99EL also induced apoptotic cell death by increasing cleaved caspase-3 and decreasing anti-apoptotic proteins Bcl-2 and Bcl-xL. In an in vivo syngeneic breast cancer mouse model, 100 mg/kg CO99EL suppressed tumor growth and induced apoptosis of cancer cells. Moreover, CO99EL significantly inhibited lung metastasis from primary breast cancer.

CONCLUSIONS

Our study demonstrated that 100 mg/kg CO99EL has potent anti-tumor effects against breast cancer, thus suggesting that 100 mg/kg CO99EL has potential applications in the treatment and prevention of breast cancer.

TMEM25 inhibits monomeric EGFR-mediated STAT3 activation in basal state to suppress triple-negative breast cancer progression

Triple-negative breast cancer (TNBC) is a subtype of breast cancer with poor outcome and lacks of approved targeted therapy. Overexpression of epidermal growth factor receptor (EGFR) is found in more than 50% TNBC and is suggested as a driving force in progression of TNBC; however, targeting EGFR using antibodies to prevent its dimerization and activation shows no significant benefits for TNBC patients. Here we report that EGFR monomer may activate signal transducer activator of transcription-3 (STAT3) in the absence of transmembrane protein TMEM25, whose expression is frequently decreased in human TNBC. Deficiency of TMEM25 allows EGFR monomer to phosphorylate STAT3 independent of ligand binding, and thus enhances basal STAT3 activation to promote TNBC progression in female mice. Moreover, supplying TMEM25 by adeno-associated virus strongly suppresses STAT3 activation and TNBC progression. Hence, our study reveals a role of monomeric-EGFR/STAT3 signaling pathway in TNBC progression and points out a potential targeted therapy for TNBC.

Epigenetic programing of cancer stemness by transcription factors-non-coding RNAs interactions

Cancer 'stemness' is fundamental to cancer existence. It defines the ability of cancer cells to indefinitely perpetuate as well as differentiate. Cancer stem cell populations within a growing tumor also help evade the inhibitory effects of chemo- as well as radiation-therapies, in addition to playing an important role in cancer metastases. NF-κB and STAT-3 are representative transcription factors (TFs) that have long been associated with cancer stemness, thus presenting as attractive targets for cancer therapy. The growing interest in non-coding RNAs (ncRNAs) in the recent years has provided further insight into the mechanisms by which TFs influence cancer stem cell characteristics. There is evidence for a direct regulation of TFs by ncRNAs, such as, microRNAs (miRNAs), long non-coding RNAs (lncRNAs) as well as circular RNAs (circRNAs), and vice versa. Additionally, the TF-ncRNAs regulations are often indirect, involving ncRNA-target genes or the sponging of other ncRNA species by individual ncRNAs. The information is rapidly evolving and this review provides a comprehensive review of TF-ncRNAs interactions with implications on cancer stemness and in response to therapies. Such knowledge will help uncover the many levels of tight regulations that control cancer stemness, providing novel opportunities and targets for therapy in the process.

Palmitic Acid Inhibits the Growth and Metastasis of Gastric Cancer by Blocking the STAT3 Signaling Pathway

Lipidomic analyses have suggested that palmitic acid (PA) is linked to gastric cancer. However, its effects and action mechanisms remain unclear. Therefore, we evaluated the effects of PA on cell proliferation, invasion, and apoptosis in human gastric cancer, as well as the role of p-STAT3 in mediating its effects. The results of the MTT and colony formation assays revealed that PA blocked gastric cancer cell proliferation in a concentration-dependent manner. The EdU-DNA assay indicated that 50 μM of PA could block gastric cell proliferation by 30.6-80.0%. The Transwell assay also confirmed the concentration dependence of PA-induced inhibitory effect on cell invasion. The flow cytometry analysis indicated that PA treatment for 18 h could induce gastric cancer cell apoptosis. The immunohistochemical staining revealed that p-STAT3 levels were higher in the gastric cancer tissues than in the control tissues. We demonstrated that PA treatment for 12 h decreased the expressions of p-STAT3, p-JAK2, N-cadherin, and vimentin, and inhibited the nuclear expression of p-STAT3 in gastric cancer cells. Finally, PA treatment (50 mg/kg) decreased gastric cancer growth (54.3%) in the xenograft models. Collectively, these findings demonstrate that PA inhibits cell proliferation and invasion and induces human gastric cancer cell apoptosis.

Hispolon Methyl Ether, a Hispolon Analog, Suppresses the SRC/STAT3/Survivin Signaling Axis to Induce Cytotoxicity in Human Urinary Bladder Transitional Carcinoma Cell Lines

Bladder cancer is a leading human malignancy worldwide. Signal transducer and activator of transcription (STAT) 3 is an oncogenic transcription factor commonly hyperactivated in most human cancers, including bladder cancer. Notably, preclinical evidence has validated STAT3 blockade as a promising therapeutic strategy for bladder cancer. Hispolon Methyl Ether (HME) is a structural analog of hispolon, an anticancer component of the medicinal mushroom Phellinus linteus. Thus far, HME's anticancer activity and mechanisms remain largely unknown. We herein report HME was cytotoxic, more potent than cisplatin, and proapoptotic to various human bladder transitional carcinoma cell lines. Of note, HME blocked STAT3 activation, evidenced by HME-elicited reduction in tyrosine 705-phosphorylated STAT3 levels constitutively expressed or induced by interleukin-6. Significantly, HME-induced cytotoxicity was abrogated in cells expressing a dominant-active STAT3 mutant (STAT3-C), confirming STAT3 blockage as a pivotal mechanism of HME's cytotoxic action. We further revealed that survivin was downregulated by HME, while its levels were rescued in STAT3-C-expressing cells. Moreover, survivin overexpression abolished HME-induced cytotoxicity, illustrating survivin as a central downstream mediator of STAT3 targeted by HME. Lastly, HME was shown to lower tyrosine 416-phosphorylated SRC levels, suggesting that HME inhibits STAT3 by repressing the activation of SRC, a STAT3 upstream kinase. In conclusion, we present the first evidence of HME's anti-bladder cancer effect, likely proceeding by evoking apoptosis through suppression of the antiapoptotic SRC/STAT3/survivin signaling axis.

Transcription Factors STAT3 and MYC Are Key Players of Human Platelet Lysate-Induced Cell Proliferation

Human platelet lysate (HPL) is an efficient alternative for animal serum supplements, significantly enhancing stromal cell proliferation. However, the molecular mechanism behind this growth-promoting effect remains elusive. The aim of this study was to investigate the effect of HPL on cell cycle gene expression in different human stromal cells and to identify the main key players that mediate HPL's growth-enhancing effect. RT-qPCR and an antibody array revealed significant upregulation of cell cycle genes in stromal cells cultured in HPL. As HPL is rich in growth factors that are ligands of tyrosine kinase receptor (TKR) pathways, we used TKR inhibitors and could significantly reduce cell proliferation. Genome profiling, RT-qPCR and Western blotting revealed an enhanced expression of the transcription factors signal transducer and activator of transcription 3 (STAT3) and MYC, both known TKR downstream effectors and stimulators of cell proliferation, in response to HPL. In addition, specifically blocking STAT3 resulted in reduced cell proliferation and expression of cell cycle genes. Our data indicate that HPL-enhanced cell proliferation can, at least in part, be explained by the TKR-enhanced expression of STAT3 and MYC, which in turn induce the expression of genes being involved in the promotion and control of the cell cycle.

ENO1 Binds to ApoC3 and Impairs the Proliferation of T Cells via IL-8/STAT3 Pathway in OSCC

Lymph node metastasis is associated with poor prognosis of oral squamous cell carcinoma (OSCC), and few studies have explored the relevance of postoperative lymphatic drainage (PLD) in metastatic OSCC. Alpha-enolase (ENO1) is a metabolic enzyme, which is related to lymphatic metastasis of OSCC. However, the role of ENO1 in PLD in metastatic OSCC has not been elucidated. Herein, we collected lymphatic drainage after lymphadenectomy between metastatic and non-metastatic lymph nodes in OSCC patients to investigate the relationship between ENO1 expression and metastasis, and to identify the proteins which interacted with ENO1 in PLD of patients with metastatic OSCC by MS/GST pulldown assay. Results revealed that the metabolic protein apolipoprotein C-III (ApoC3) was a novel partner of ENO1. The ENO1 bound to ApoC3 in OSCC cells and elicited the production of interleukin (IL)-8, as demonstrated through a cytokine antibody assay. We also studied the function of IL-8 on Jurkat T cells co-cultured with OSCC cells in vitro. Western blot analysis was applied to quantitate STAT3 (signal transducer and activator of transcription 3) and p-STAT3 levels. Mechanistically, OSCC cells activated the STAT3 signaling pathway on Jurkat T cells through IL-8 secretion, promoted apoptosis, and inhibited the proliferation of Jurkat T cells. Collectively, these findings illuminate the molecular mechanisms underlying the function of ENO1 in metastasis OSCC and provide new strategies for targeting ENO1 for OSCC treatment.

β-Caryophyllene Counteracts Chemoresistance Induced by Cigarette Smoke in Triple-Negative Breast Cancer MDA-MB-468 Cells

Exposure to cigarette smoke (CS) has been associated with an increased risk of fatal breast cancers and recurrence, along with chemoresistance and chemotherapy impairment. This strengthens the interest in chemopreventive agents to be exploited both in healthy and oncological subjects to prevent or repair CS damage. In the present study, we evaluated the chemopreventive properties of the natural sesquiterpene β-caryophyllene towards the damage induced by cigarette smoke condensate (CSC) in triple negative breast cancer MDA-MB-468 cells. Particularly, we assessed the ability of the sesquiterpene to interfere with the mechanisms exploited by CSC to promote cell survival and chemoresistance, including genomic instability, cell cycle progress, autophagy/apoptosis, cell migration and related pathways. β-Caryophyllene was found to be able to increase the CSC-induced death of MDA-MB-468 cells, likely triggering oxidative stress, cell cycle arrest and apoptosis; moreover, it hindered cell recovery, autophagy activation and cell migration; at last, a marked inhibition of the signal transducer and activator of transcription 3 (STAT3) activation was highlighted: this could represent a key mechanism of the chemoprevention by β-caryophyllene. Although further studies are required to confirm the in vivo efficacy of β-caryophyllene, the present results suggest a novel strategy to reduce the harmful effect of smoke in cancer patients and to improve the survival expectations in breast cancer women.

Sorafenib Chemosensitization by Caryophyllane Sesquiterpenes in Liver, Biliary, and Pancreatic Cancer Cells: The Role of STAT3/ABC Transporter Axis

A combination of anticancer drugs and chemosensitizing agents has been approached as a promising strategy to potentiate chemotherapy and reduce toxicity in aggressive and chemoresistant cancers, like hepatocellular carcinoma (HCC), cholangiocarcinoma (CCA), and pancreatic ductal adenocarcinoma (PDAC). In the present study, the ability of caryophyllane sesquiterpenes to potentiate sorafenib efficacy was studied in HCC, CCA, and PDAC cell models, focusing on the modulation of STAT3 signaling and ABC transporters; tolerability studies in normal cells were also performed. Results showed that the combination of sorafenib and caryophyllane sesquiterpenes synergized the anticancer drug, especially in pancreatic Bx-PC3 adenocarcinoma cells; a similar trend, although with lower efficacy, was found for the standard ABC transporter inhibitors. Synergistic effects were associated with a modulation of MDR1 (or Pgp) and MRP transporters, both at gene and protein level; moreover, activation of STAT3 cascade and cell migration appeared significantly affected, suggesting that the STAT3/ABC-transporters axis finely regulated efficacy and chemoresistance to sorafenib, thus appearing as a suitable target to overcome drawbacks of sorafenib-based chemotherapy in hepato-biliary-pancreatic cancers. Present findings strengthen the interest in caryophyllane sesquiterpenes as chemosensitizing and chemopreventive agents and contribute to clarifying drug resistance mechanisms in HCC, CCA, and PDAC cancers and to developing possible novel therapeutic strategies.