Inhibition of IL-6/STAT3 signaling in human cancer cells using Evista

Potential therapeutic targets of the JAK2/STAT3 signaling pathway in triple-negative breast cancer

Triple-negative breast cancer (TNBC) poses a significant clinical challenge due to its propensity for metastasis and poor prognosis. TNBC evades the body's immune system recognition and attack through various mechanisms, including the Janus Kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signaling pathway. This pathway, characterized by heightened activity in numerous solid tumors, exhibits pronounced activation in specific TNBC subtypes. Consequently, targeting the JAK2/STAT3 signaling pathway emerges as a promising and precise therapeutic strategy for TNBC. The signal transduction cascade of the JAK2/STAT3 pathway predominantly involves receptor tyrosine kinases, the tyrosine kinase JAK2, and the transcription factor STAT3. Ongoing preclinical studies and clinical research are actively investigating this pathway as a potential therapeutic target for TNBC treatment. This article comprehensively reviews preclinical and clinical investigations into TNBC treatment by targeting the JAK2/STAT3 signaling pathway using small molecule compounds. The review explores the role of the JAK2/STAT3 pathway in TNBC therapeutics, evaluating the benefits and limitations of active inhibitors and proteolysis-targeting chimeras in TNBC treatment. The aim is to facilitate the development of novel small-molecule compounds that target TNBC effectively. Ultimately, this work seeks to contribute to enhancing therapeutic efficacy for patients with TNBC.

Ubiquitin-specific peptidase 14 maintains estrogen receptor α stability via its deubiquitination activity in endometrial cancer

USP14 deubiquitinates ERα to maintain its stability in ECEndometrial cancer (EC) is one of the common gynecological malignancies of which the incidence has been rising for decades. It is considered that continuously unopposed estrogen exposure is the main risk factor for EC initiation. Thus, exploring the modulation of estrogen/estrogen receptor α (ERα) signaling pathway in EC would be helpful to well understand the mechanism of EC development and find the potential target for EC therapy. Ubiquitin-specific peptidase 14 (USP14), a member of the proteasome-associated deubiquitinating enzyme family, plays a crucial role in a series of tumors. However, the function of USP14 in EC is still elusive. Here, our results have demonstrated that USP14 is highly expressed in EC tissues compared with that in normal endometrial tissues, and higher expression of USP14 is positively correlated with poor prognosis. Moreover, USP14 maintains ERα stability through its deubiquitination activity. Our results further demonstrate that USP14 depletion decreases the expression of ERα-regulated genes in EC-derived cell lines. Moreover, knockdown of USP14 or USP14-specific inhibitor treatment significantly suppresses cell growth and migration in EC cell lines or in mice. We further provide the evidence to show that the effect of USP14 on EC cell growth, if not all, at least is partially related to ERα pathway. Our study provides new sights for USP14 to be a potential therapeutic target for the treatment of EC, especially for EC patients with fertility preservation needs.

STAT family of transcription factors in breast cancer: Pathogenesis and therapeutic opportunities and challenges

Breast cancer is the most commonly diagnosed cancer and second-leading cause of cancer deaths in women. Breast cancer stem cells (BCSCs) promote metastasis and therapeutic resistance contributing to tumor relapse. Through activating genes important for BCSCs, transcription factors contribute to breast cancer metastasis and therapeutic resistance, including the signal transducer and activator of transcription (STAT) family of transcription factors. The STAT family consists of six major isoforms, STAT1, STAT2, STAT3, STAT4, STAT5, and STAT6. Canonical STAT signaling is activated by the binding of an extracellular ligand to a cell-surface receptor followed by STAT phosphorylation, leading to STAT nuclear translocation and transactivation of target genes. It is important to note that STAT transcription factors exhibit diverse effects in breast cancer; some are either pro- or anti-tumorigenic while others maintain dual, context-dependent roles. Among the STAT transcription factors, STAT3 is the most widely studied STAT protein in breast cancer for its critical roles in promoting BCSCs, breast cancer cell proliferation, invasion, angiogenesis, metastasis, and immune evasion. Consequently, there have been substantial efforts in developing cancer therapeutics to target breast cancer with dysregulated STAT3 signaling. In this comprehensive review, we will summarize the diverse roles that each STAT family member plays in breast cancer pathobiology, as well as, the opportunities and challenges in pharmacologically targeting STAT proteins and their upstream activators in the context of breast cancer treatment.

IL-6/JAK/STAT3 Signaling in Breast Cancer Metastasis: Biology and Treatment

Breast cancer is the most commonly diagnosed cancer in women. Metastasis is the primary cause of mortality for breast cancer patients. Multiple mechanisms underlie breast cancer metastatic dissemination, including the interleukin-6 (IL-6)-mediated signaling pathway. IL-6 is a pleiotropic cytokine that plays an important role in multiple physiological processes including cell proliferation, immune surveillance, acute inflammation, metabolism, and bone remodeling. IL-6 binds to the IL-6 receptor (IL-6Rα) which subsequently binds to the glycoprotein 130 (gp130) receptor creating a signal transducing hexameric receptor complex. Janus kinases (JAKs) are recruited and activated; activated JAKs, in turn, phosphorylate signal transducer and activator of transcription 3 (STAT3) for activation, leading to gene regulation. Constitutively active IL-6/JAK/STAT3 signaling drives cancer cell proliferation and invasiveness while suppressing apoptosis, and STAT3 enhances IL-6 signaling to promote a vicious inflammatory loop. Aberrant expression of IL-6 occurs in multiple cancer types and is associated with poor clinical prognosis and metastasis. In breast cancer, the IL-6 pathway is frequently activated, which can promote breast cancer metastasis while simultaneously suppressing the anti-tumor immune response. Given these important roles in human cancers, multiple components of the IL-6 pathway are promising targets for cancer therapeutics and are currently being evaluated preclinically and clinically for breast cancer. This review covers the current biological understanding of the IL-6 signaling pathway and its impact on breast cancer metastasis, as well as, therapeutic interventions that target components of the IL-6 pathway including: IL-6, IL-6Rα, gp130 receptor, JAKs, and STAT3.

Importance of STAT3 signalling in cancer, metastasis and therapeutic interventions

The Signal Transducer and Activator of Transcription 3 (STAT3) protein is encoded on chromosome 17q21. The SH2 and the DNA binding domains are critical structural components of the protein, together with tyrosine and serine residues that initiate phosphorylation. STAT3 interacts with DNA directly and functions in cells as both a signal transducer and a transcription factor. Its cytoplasmic activation results in dimerisation and nuclear translocation, where it is involved in the transcription of a large number of target genes. STAT3 is hyperactive in cancer cells as a result of upstream STAT3 mutations or enhanced cytokine production in the tumour environment. The STAT3 signalling pathway promotes many hallmarks of carcinogenesis and metastasis, including enhanced cell proliferation and survival, as well as migration and invasion into the extracellular matrix. Recent investigations into novel STAT3-based therapies describe a range of innovative approaches, such as the use of novel oligonucleotide drugs. These limit STAT3 binding to its target genes by attaching to SH2 and DNA-binding domains. Yet, despite these significant steps in understanding the underpinning mechanisms, there are currently no therapeutic agents that addresses STAT3 signalling in a clinically relevant manner.

Shikonin suppresses colon cancer cell growth and exerts synergistic effects by regulating ADAM17 and the IL‑6/STAT3 signaling pathway

Signal transducer and activator of transcription 3 (STAT3) activation is associated with drug resistance induced by anti-epidermal growth factor receptor (anti-EGFR) therapy in the treatment of colon cancer. Thus, the combined inhibition of EGFR and STAT3 may prove beneficial for this type of cancer. STAT3 has been proven to play a critical role in colon cancer initiation and progression, and is considered the primary downstream effector driven by interleukin-6 (IL-6). A disintegrin and metalloproteinase 17 (ADAM17), documented as an oncogene, catalyzes the cleavage of both EGF and IL-6R, inducing EGFR signaling and enabling IL-6 trans-signaling to activate STAT3 in a wide range of cell types to promote inflammation and cancer development. As a natural product, shikonin (SKN) has been found to function as an antitumor agent; however, its role in the regulation of ADAM17 and IL-6/STAT3 signaling in colon cancer cells remains unknown. In the present study, it was found that SKN inhibited colon cancer cell growth, suppressed both constitutive and IL-6-induced STAT3 phosphorylation, and downregulated the expression of ADAM17. ADAM17 expression was not altered in response to STAT3 knockdown, while IL-6-induced STAT3 activation did not induce ADAM17 transcripts. Furthermore, it was demonstrated that SKN did not affect the expression of key proteins involved in the maturation and degradation of ADAM17. SKN decreased ADAM17 expression possibly through reactive oxygen species (ROS)-mediated translational inhibition, as evidenced by the increased ADAM17 mRNA and phosphorylation levels of eukaryotic initiation factor 2α (eIF2α). The expression of ADAM17 and p-eIF2α was reversed by N-acetylcysteine (NAC, a ROS scavenger). Taken together, these results indicate that the concurrent inhibition of ADAM17 and IL-6/STAT3 signaling by SKN may synergistically contribute to the suppression of colon cancer cell growth.

IL-6 in the Ecosystem of Head and Neck Cancer: Possible Therapeutic Perspectives

Interleukin-6 (IL-6) is a highly potent cytokine involved in multiple biological processes. It was previously reported to play a distinct role in inflammation, autoimmune and psychiatric disorders, ageing and various types of cancer. Furthermore, it is understood that IL-6 and its signaling pathways are substantial players in orchestrating the cancer microenvironment. Thus, they appear to be potential targets in anti-tumor therapy. The aim of this article is to elucidate the role of IL-6 in the tumor ecosystem and to review the possible therapeutic approaches in head and neck cancer.

Raloxifene Protects Cisplatin-Induced Renal Injury in Mice via Inhibiting Oxidative Stress

Purpose

Cisplatin is one of the most widely used antineoplastic drugs but has limited therapeutic effects due to nephrotoxicity. The aim of this study was to determine the possible renoprotective effect of the antioxidant raloxifene on cisplatin-induced nephrotoxicity in mice.

Materials and Methods

Cisplatin-induced acute renal injury was established in female C57 mice that were treated with saline (normal control) or raloxifene over a 7-day period. The body weight of the mice was recorded. Histopathological examinations of the kidney tissues were performed using H&E, PAS staining and TEM. The histomorphology of liver and other organs was observed by H&E staining. The serum levels of creatinine, blood urea nitrogen (BUN), alanine transaminase (ALT) and glutamic oxalacetic transaminase (AST) were analyzed by specific kits. Superoxide dismutase (SOD) and glutathione (GSH) activity, and the content of malondialdehyde (MDA) in the kidney, liver homogenates and HK-2 cells were measured by WST-8 and thiobarbituric acid colorimetric methods. Moreover, the mitochondrial structures of HK-2 cells were performed using TEM. The viability and proliferation of HK-2 cells were examined by CCK-8 and EdU incorporation assays. The mitochondrial membrane potential was measured by JC-1 fluorescence.

Results

Raloxifene significantly reduced the levels of serum creatinine, urea, ALT and AST in the cisplatin-treated mice, and alleviated cisplatin-induced renal and hepatic tissue injury. Furthermore, raloxifene also increased the activity of GSH and SOD in the renal tissues and HK-2 cells, and reduced MDA levels, thereby limiting oxidative stress in the kidney.

Conclusion

Raloxifene protected against cisplatin-induced nephrotoxicity by activating the antioxidant system, along with alleviating liver damage. It should be considered as a potential adjuvant in cisplatin-based chemotherapeutic protocols.

Radioprotective Role of Natural Polyphenols: From Sources to Mechanisms

The identification and development of radioprotective agents has emerged as a subject matter of research during recent years due to the growing usage of ionizing radiation in different areas of human life. Previous work on synthetic radioprotectors has achieved limited progress because of the numerous issues associated with toxicity. Compounds extracted from plants have potential to serve as lead candidates for developing ideal radioprotectors due to their low cost, safety and selectivity. Polyphenols are the most abundant and commonly dispersed group of biologically active molecules possessing broad range of pharmacological activities. Polyphenols have displayed efficacy for radioprotection during various investigations and can be administered at high doses with lesser toxicity. Detoxification of free radicals, modulating inflammatory responses, DNA repair, stimulation of hematopoietic recovery, and immune functions are the main mechanisms for radiation protection with polyphenols. Epicatechin, epigallocatechin-3-gallate, apigenin, caffeic acid phenylethylester, and silibinin provide cytoprotection together with the suppression of many pro-inflammatory cytokines owing to their free radical scavenging, anti-oxidant, and anti-inflammatory properties. Curcumin, resveratrol, quercetin, gallic acid, and rutin's radioprotective properties are regulated primarily by direct or indirect decline in cellular stress. Thus, polyphenols may serve as potential candidates for radioprotection in the near future, however, extensive investigations are still required to better understand their protection mechanisms.

Bazedoxifene exhibits anti-inflammation and anti-atherosclerotic effects via inhibition of IL-6/IL-6R/STAT3 signaling

Atherosclerosis is regarded as chronic inflammatory disease. The IL-6/STAT3 pathway plays an important role in inflammation. We previously described a small-molecule compound, Bazedoxifene, which target IL-6/STAT3 pathway and has been approved for clinical use for osteoporosis in postmenopausal women. The aim of this study is to evaluate the effect of Bazedoxifene in the progression of atherosclerosis in apolipoprotein E-deficient (ApoE-/-) mice. Five-week-old male ApoE-/- mice were fed with High-fat diet (HFD) containing 5 mg/kg Bazedoxifene or a matching control for 12 weeks. Oil red O (ORO) staining was used to detect plaque size; immunohistochemical staining was used to detect the presence of endothelial cells, vascular muscle cells and phosphorylated STAT3 (P-STAT3) in localized plaques. The potential underlying mechanisms in human umbilical vein endothelial cells (HUVECs) and vascular muscle cells (VSMCs) was detected by Western blot analysis, Wound healing assay and Elisa assay. In the ApoE-/- mice fed with HFD, daily Bazedoxifene administration effectively attenuated atherosclerotic plaque area (P < 0.01), down-regulated IL-6 levels (P < 0.01), decreased STAT3 phosphorylation, reduced VSMCs proliferation and increased endothelial coverage in aortic vessels. Interestingly, we found HUVECs lack of membrane IL-6 receptor (IL-6R) compared to VSMCs (P < 0.01). Furthermore, we found that the soluble IL-6 receptor (sIL6R) participates in the activation of STAT3 induced by IL-6 or TNF-α in HUVECs and primary HUVECs. Bazedoxifene did not inhibit the growth of HUVECs while suppressing the proliferation of VSMCs. Bazedoxifene is an attractive novel therapeutic reagent for atherosclerosis diseases. This mechanism may be partially attributed to regulating IL-6/IL-6R/STAT3 signaling pathway.

Raloxifene inhibits pancreatic adenocarcinoma growth by interfering with ERβ and IL-6/gp130/STAT3 signaling

PURPOSE

Currently, the exact role of estrogen receptor (ER) signaling in pancreatic cancer is unknown. Recently, we showed that expression of phosphorylated ERβ correlates with a poor prognosis in patients with pancreatic ductal adenocarcinoma (PDAC). Here, we hypothesized that raloxifene, a FDA-approved selective ER modulator (SERM), may suppress PDAC tumor growth by interfering with ERβ signaling. To test this hypothesis, we studied the impact of raloxifene on interleukin-6/glycoprotein-130/signal transducer and activator of transcription-3 (IL-6/gp130/STAT3) signaling.

METHODS

Human PDAC cell lines were exposed to raloxifene after which growth inhibition was assessed using a BrdU assay. ER knockdown was performed using siRNAs specific for ERα and ERβ. The effects of raloxifene on IL-6 expression and STAT3 phosphorylation in PDAC cells were assessed by ELISA and Western blotting, respectively. In addition, raloxifene was administered to an orthotopic PDAC tumor xenograft mouse model, after which tumor growth was monitored and immunohistochemistry was performed.

RESULTS

Raloxifene inhibited the in vitro growth of PDAC cells, and this effect was reversed by siRNA-mediated knockdown of ERβ, but not of ERα, indicating ER isotype-specific signaling. We also found that treatment with raloxifene inhibited the release of IL-6 and suppressed the phosphorylation of STAT3Y705 in PDAC cells. In vivo, we found that orthotopic PDAC tumor growth, lymph node and liver metastases as well as Ki-67 expression were reduced in mice treated with raloxifene.

CONCLUSIONS

Inhibition of ERβ and the IL-6/gp130/STAT3 signaling pathway by raloxifene leads to potent reduction of PDAC growth in vitro and in vivo. Our results suggest that ERβ signaling and IL-6/gp130 interaction may serve as promising drug targets for pancreatic cancer and that raloxifene may serve as an attractive therapeutic option for PDAC patients expressing the ERβ isotype.

Tamoxifen attenuates reactive astrocyte-induced brain metastasis and drug resistance through the IL-6/STAT3 signaling pathway

Brain metastasis affects approximately 20%-30% of patients with triple-negative breast cancers (TNBCs). Even small metastatic lesions in the brain can trigger severe neurological impairments and result in extremely short survival time. Recently, active astrocytes were reported to be associated with brain metastases. However, how activated astrocytes regulate the behaviors of disseminated breast cancer cells in the brain remains unknown. In this study, human primary astrocytes were stimulated with IL-1β to form active astrocytes to study the cross-talk between stromal cells (astrocytes) and TNBC cells in brain metastases. Our results showed that active astrocytes significantly increase the malignancy of TNBC cells and prevent them from undergoing apoptosis caused by doxorubicin. We also found that the high level of IL-6 secreted by activated astrocytes was responsible for the drug resistance of breast cancer, which could be abolished by treatment of astrocytes with tamoxifen (TAM). The blockage of active astrocyte-derived IL-6 by a neutralizing antibody resulted in the attenuation of drug resistance, consequently enhancing the sensitivity of breast cancer cells to doxorubicin. Furthermore, the possible involved TAM-modulated drug resistance mechanism may be associated with a decrease in IL-6 expression in astrocytes and the downregulation of MAPK and JAK2/STAT3 signaling in cancer cells. Our data suggested that TAMs might reduce drug resistance through the IL-6/JAK2/STAT3 signaling pathway, providing a possible therapy to treat brain metastasis in TNBCs, as estrogen receptor inhibitors (TAMs, etc.) can cross the blood-brain barrier.

An H3K4me3 reader, BAP18 as an adaptor of COMPASS-like core subunits co-activates ERα action and associates with the sensitivity of antiestrogen in breast cancer

Estrogen receptor alpha (ERα) signaling pathway is essential for ERα-positive breast cancer progression and endocrine therapy resistance. Bromodomain PHD Finger Transcription Factor (BPTF) associated protein of 18kDa (BAP18) has been recognized as a crucial H3K4me3 reader. However, the whole genomic occupation of BAP18 and its biological function in breast cancer is still elusive. Here, we found that higher expression of BAP18 in ERα-positive breast cancer is positively correlated with poor prognosis. ChIP-seq analysis further demonstrated that the half estrogen response elements (EREs) and the CCCTC binding factor (CTCF) binding sites are the significant enrichment sites found in estrogen-induced BAP18 binding sites. Also, we provide the evidence to demonstrate that BAP18 as a novel co-activator of ERα is required for the recruitment of COMPASS-like core subunits to the cis-regulatory element of ERα target genes in breast cancer cells. BAP18 is recruited to the promoter regions of estrogen-induced genes, accompanied with the enrichment of the lysine 4-trimethylated histone H3 tail (H3K4me3) in the presence of E2. Furthermore, BAP18 promotes cell growth and associates the sensitivity of antiestrogen in ERα-positive breast cancer. Our data suggest that BAP18 facilitates the association between ERα and COMPASS-like core subunits, which might be an essential epigenetic therapeutic target for breast cancer.

Coagulopathy in COVID-19: Focus on vascular thrombotic events

SARS-CoV-2 causes a phenotype of pneumonia with diverse manifestation, which is termed as coronavirus disease 2019 (COVID-19). An impressive high transmission rate allows COVID-19 conferring enormous challenge for clinicians worldwide, and developing to a pandemic level. Combined with a series of complications, a part of COVID-19 patients progress into severe cases, which critically contributes to the risk of fatality. To date, coagulopathy has been found as a prominent feature of COVID-19 and severe coagulation dysfunction may be associated with poor prognosis. Coagulopathy in COVID-19 may predispose patients to hypercoagulability-related disorders including thrombosis and even fatal vascular events. Inflammatory storm, uncontrolled inflammation-mediated endothelial injury and renin angiotensin system (RAS) dysregulation are the potential mechanisms. Ongoing efforts made to develop promising therapies provide several potential strategies for hypercoagulability in COVID-19. In this review, we introduce the clinical features of coagulation and the increased vascular thrombotic risk conferred by coagulopathy according to present reports about COVID-19. The potential underlying mechanisms and emerging therapeutic avenues are discussed, emphasizing an urgent need for effective interventions.

Raloxifene inhibits IL-6/STAT3 signaling pathway and protects against high-fat-induced atherosclerosis in ApoE-/- mice

AIMS

The signal transducer and activator of transcription 3 (STAT3) pathway plays an important role in inflammatory cascade process. Our previous studies found that Raloxifene targeted against IL-6/GP130 protein-protein interface and inhibited STAT3 phosphorylation induced by IL-6 in cancer cells. However, whether Raloxifene could suppress IL-6/STAT3 signaling pathway and attenuate atherosclerosis in high-fat diet (HFD)-induced mice remains unknown. The objective of this study was to explore the potential effect of Raloxifene on the prevention of atherosclerosis.

MAIN METHODS

HFD-induced atherosclerosis was established in apoliprotein E-deficient (ApoE ^-/-) mice. Mice by daily intragastric gavage with Raloxifene or vehicle as controls were provided. The human umbilical vein endothelial cells (HUVEC), Rat VSMC and RAW264.7 cell lines were used to evaluate the effect of Raloxifene in vitro.

KEY FINDINGS

We demonstrated that Raloxifene was effective in ameliorating HFD- induced atherosclerosis plaque burden and size. Histological analysis showed that the expression of IL-6, P-STAT3, ICAM-1, VCAM-1, CD68 and α-SMA were significantly decreased in the Raloxifene intervention group compared to HFD group. Moreover, we observed that IL-6 increased migration and cell viability of VSMCs and RAW264.7 cells, while Raloxifene treatment decreased migration and reduced cell viability of VSMCs and RAW264.7 cells stimulated by IL-6. Furthermore, this effect was related to blocking IL-6/STAT3 pathway.

SIGNIFICANCE

Raloxifene has effects on inhibiting atherosclerosis development, the underlying mechanisms might involve in inhibiting inflammation-related IL-6/STAT3 signaling pathway.

Cell Death by Gallotannin Is Associated with Inhibition of the JAK/STAT Pathway in Human Colon Cancer Cells

Background

Gallotannin (GT) is a polyphenol that possesses interesting anticancer properties. However, the mechanisms underlying its antitumor effects have not been well defined.

Objective

This study was designed to clarify the mechanisms underlying GT antitumor effects in colon cancer cell lines.

Methods

Three isogenic HCT116 cell lines (p53^+/+, p53^-/-, and p21^-/-) were treated with GT for different time points then Western blot, flow cytometry, and senescence analysis were performed to examine the effect of GT on Mitogen-activated protein kinase (MAPK) and Janus kinase (JAK)/signal transducer and activator of transcription (STAT) effectors, STAT3 downstream apoptotic targets, Sub-G1 phase, and programmed cell death induction. Transfection using Invitrogen Lipofectamine 2000 Transfection Reagent (Thermo Fisher Scientific, Waltham, Massachusetts) were used to identify the role of p53 and p21 in the p53^-/- and p21^-/- cell lines.

Results

Both low and high GT concentrations caused MAPKs activation marked by upregulation of extracellular signal-regulated kinase (p-ERK). The preincubation with the antioxidant Tiron (Sigma-Aldrich, St Louis, Missouri) showed that GT's antitumor effects were not mediated by reactive oxygen species. We then examined the effect of GT on the JAK/STAT pathway, which is known to be activated in colorectal cancer. GT totally inhibited the JAK/STAT pathway effectors JAK2, STAT1, and STAT3 and their downstream apoptotic regulators B-cell lymphoma-extra large (Bcl-x_L) and c-Myc in all 3 cell lines. HCT116 cancer cells exhibited differential sensitivity to GT with p21^-/- cells being the most sensitive and p53^+/+ cells that express p21 protein being the least sensitive. In p53^+/+ cells, GT induced senescence, whereas in p53^-/- and p21^-/- cells, GT induced apoptosis in a caspase independent manner marked by Poly(ADP-Ribose) Polymerase (PARP) cleavage, Bcl-2 downregulation, and upregulation of the Bcl-2 associated X (Bax) to B-cell lymphoma 2 (Bcl-2) ratio. In addition, the sub-G1 phase exceeded 50% in p21^-/- cells.

Conclusions

Considered together, our results indicate that GT is potent inhibitor of the JAK/STAT pathway in colon cancer irrespective of the p53 and p21 status, which provides insights into its mechanism of anticancer activities and future potential for clinical translation. (Curr Ther Res Clin Exp. 2020; 81:XXX-XXX).

The anti-tumor activity of pralatrexate (PDX) correlates with the expression of RFC and DHFR mRNA in preclinical models of multiple myeloma

Multiple myeloma (MM) is the second most common hematologic malignancy. While major advances have been made in the disease, it is still incurable. Although antifolate-based drugs are not commonly used to treat myeloma, new generation analogs with distinct patterns of preclinical and clinical activity may offer an opportunity to identify new classes of potentially active drugs. Pralatrexate (PDX), which was approved for the treatment of relapsed or refractory peripheral T-cell lymphoma in 2009, may be one such drug. Pralatrexate exhibits a potency and pattern of activity distinct from its predecessors like methotrexate (MTX). We sought to understand the activity and mechanisms of resistance of multiple myeloma to these drugs, which could also offer potential strategies for selective use of the drug. We demonstrate that PDX and MTX both induce a significant decrease in cell viability in the low nanomolar range, with PDX exhibiting a more potent effect. We identified a series of myeloma cell lines exhibiting markedly different patterns of sensitivity to the drugs, with some lines frankly resistant, and others exquisitely sensitive. These differences were largely attributed to the basal RFC (Reduced Folate Carrier) mRNA expression levels. RFC mRNA expression correlated directly with rates of drug uptake, with the most sensitive lines exhibiting the most significant intracellular accumulation of pralatrexate. This mechanism explains the widely varying patterns of sensitivity and resistance to pralatrexate in multiple myeloma cell lines. These findings could have implications for this class of drugs and their role in the treatment of multiple myeloma.

Cellular Plasticity in Breast Cancer Progression and Therapy

With the exception of non-melanoma skin cancer, breast cancer is the most frequently diagnosed malignant disease among women, with the majority of mortality being attributable to metastatic disease. Thus, even with improved early screening and more targeted treatments which may enable better detection and control of early disease progression, metastatic disease remains a significant problem. While targeted therapies exist for breast cancer patients with particular subtypes of the disease (Her2+ and ER/PR+), even in these subtypes the therapies are often not efficacious once the patient's tumor metastasizes. Increases in stemness or epithelial-to-mesenchymal transition (EMT) in primary breast cancer cells lead to enhanced plasticity, enabling tumor progression, therapeutic resistance, and distant metastatic spread. Numerous signaling pathways, including MAPK, PI3K, STAT3, Wnt, Hedgehog, and Notch, amongst others, play a critical role in maintaining cell plasticity in breast cancer. Understanding the cellular and molecular mechanisms that regulate breast cancer cell plasticity is essential for understanding the biology of breast cancer progression and for developing novel and more effective therapeutic strategies for targeting metastatic disease. In this review we summarize relevant literature on mechanisms associated with breast cancer plasticity, tumor progression, and drug resistance.

Curcumin-Mediated Apoptotic Cell Death in Papillary Thyroid Cancer and Cancer Stem-Like Cells through Targeting of the JAK/STAT3 Signaling Pathway

The constitutive activation of Janus Kinase/Signal Transducer and Activator of Transcription (JAK/STAT) signal transduction is well elucidated in STAT3-mediated oncogenesis related to thyroid cancer and is considered to be a plausible therapeutic target. Hence, we investigated whether curcumin, a natural compound, can target the JAK/STAT3 signaling pathway to induce cytotoxic effects in papillary thyroid cancer (PTC) cell lines (BCPAP and TPC-1) and derived thyroid cancer stem-like cells (thyrospheres). Curcumin suppressed PTC cell survival in a dose-dependent manner via the induction of caspase-mediated apoptosis and caused the attenuation of constitutively active STAT3 (the dephosphorylation of Tyr705-STAT3) without affecting STAT3. Gene silencing with STAT3-specific siRNA showed the modulation of genes associated with cell growth and proliferation. The cotreatment of PTC cell lines with curcumin and cisplatin synergistically potentiated cytotoxic effects via the suppression of JAK/STAT3 activity along with the inhibition of antiapoptotic genes and the induction of proapoptotic genes, and it also suppressed the migration of PTC cells by downregulating matrix metalloproteinases and the inhibition of colony formation. Finally, thyrospheres treated with curcumin and cisplatin showed suppressed STAT3 phosphorylation, a reduced formation of thyrospheres, and the downregulated expression of stemness markers, in addition to apoptosis. The current study's findings suggest that curcumin synergistically enhances the anticancer activity of cisplatin in PTC cells as well as in cancer stem-like cells by targeting STAT3, which suggests that curcumin combined with chemotherapeutic agents may provide better therapeutic outcomes.

Non-lethal proteasome inhibition activates pro-tumorigenic pathways in multiple myeloma cells

Multiple myeloma (MM) is a haematological malignancy being characterized by clonal plasma cell proliferation in the bone marrow. Targeting the proteasome with specific inhibitors (PIs) has been proven a promising therapeutic strategy and PIs have been approved for the treatment of MM and mantle‐cell lymphoma; yet, while outcome has improved, most patients inevitably relapse. As relapse refers to MM cells that survive therapy, we sought to identify the molecular responses induced in MM cells after non‐lethal proteasome inhibition. By using bortezomib (BTZ), epoxomicin (EPOX; a carfilzomib‐like PI) and three PIs, namely Rub999, PR671A and Rub1024 that target each of the three proteasome peptidases, we found that only BTZ and EPOX are toxic in MM cells at low concentrations. Phosphoproteomic profiling after treatment of MM cells with non‐lethal (IC₁₀) doses of the PIs revealed inhibitor‐ and cell type‐specific readouts, being marked by the activation of tumorigenic STAT3 and STAT6. Consistently, cytokine/chemokine profiling revealed the increased secretion of immunosuppressive pro‐tumorigenic cytokines (IL6 and IL8), along with the inhibition of potent T cell chemoattractant chemokines (CXCL10). These findings indicate that MM cells that survive treatment with therapeutic PIs shape a pro‐tumorigenic immunosuppressive cellular and secretory bone marrow microenvironment that enables malignancy to relapse.

Bayesian Inference Identifies Combination Therapeutic Targets in Breast Cancer

OBJECTIVE

Breast cancer is the second leading cause of cancer death among US women; hence, identifying potential drug targets is an ever increasing need. In this paper, we integrate existing biological information with graphical models to deduce the significant nodes in the breast cancer signaling pathway.

METHODS

We make use of biological information from the literature to develop a Bayesian network. Using the relevant gene expression data we estimate the parameters of this network. Then, using a message passing algorithm, we infer the network. The inferred network is used to quantitatively rank different interventions for achieving a desired phenotypic outcome. The particular phenotype considered here is the induction of apoptosis.

RESULTS

Theoretical analysis pinpoints to the role of Cryptotanshinone, a compound found in traditional Chinese herbs, as a potent modulator for bringing about cell death in the treatment of cancer.

CONCLUSION

Using a mathematical framework, we showed that the combination therapy of mTOR and STAT3 genes yields the best apoptosis in breast cancer.

SIGNIFICANCE

The computational results we arrived at are consistent with the experimental results that we obtained using Cryptotanshinone on MCF-7 breast cancer cell lines and also by the past results of others from the literature, thereby demonstrating the effectiveness of our model.

Interleukin-6 induced by YAP in hepatocellular carcinoma cells recruits tumor-associated macrophages

Tumor-associated macrophages (TAMs) has been regarded as the most prominent component in tumor microenvironment. The correlation between TAM density and poor prognosis in Hepatocellular carcinoma (HCC) patients suggests a supportive role for TAMs in tumor progression. Here we employed a co-culture system to interrogate the molecular link between Yes-Associated Protein (YAP) and TAMs chemotaxis in HCC cells. We found that YAP activation was critical for the recruitment of TAMs towards HCC cells. Furthermore, cytokine array and quantitative RT-PCR analyses showed that IL-6 secreted by YAP-activated HCC cells might induce the TAMs recruitment. Interrupting YAP function by statins, the inhibitors of hydroxymethylglutaryl-CoA reductase, could robustly suppress the chemotaxis of TAMs. Together with our findings that the expression levels ofIL-6inhumanHCC tumors were highly correlated with the prognosis of HCC patients, the current study highlight the possibility of improving HCC treatment by targeting YAP-IL-6 mediated TAMs recruitment.

IL-6 family cytokines: Key inflammatory mediators as biomarkers and potential therapeutic targets

IL-6 is a critical cytokine in acute phase response and involved in the pathogenesis of several chronic inflammatory diseases including cancer. Studies have highlighted that levels of IL-6 and its family members can be useful for diagnosis, prognosis of relapse-free survival and recurrence. IL-6 family cytokines have been identified as cancer biomarkers through screening of inflammatory mediators in different fluids including saliva, serum, and bronchoalveolar lavage fluid (BALF). IL-6 can be modulated by chemopreventive drugs, small molecules, monoclonal antibodies and immune checkpoint inhibitors. Unveiling the different sources of IL-6, the interaction between IL-6 and its cellular targets, the IL-6-dependent tumor resistance mechanisms, and the identification of novel regulators of IL-6 are some of the highly complex topics included in this review and their understanding could aid cancer biomarkers and therapy development.