Activation of estrogen receptor blocks interleukin-6-inducible cell growth of human multiple myeloma involving molecular cross-talk between estrogen receptor and STAT3 mediated by co-regulator PIAS3

Obesity and myeloma: Clinical and mechanistic contributions to disease progression

Obesity and obesogenic behaviors are positively associated with both monoclonal gammopathy of unknown significance (MGUS) and multiple myeloma (MM). As the only known modifiable risk factor, this association has emerged as a new potential target for MM prevention, but little is known about the mechanistic relationship of body weight with MM progression. Here we summarize epidemiological correlations between weight, body composition, and the various stages of myeloma disease progression and treatments, as well as the current understanding of the molecular contributions of obesity-induced changes in myeloma cell phenotype and signaling. Finally, we outline groundwork for the future characterization of the relationship between body weight patterns, the bone marrow microenvironment, and MM pathogenesis in animal models, which have the potential to impact our understanding of disease pathogenesis and inform MM prevention messages.

Son of sevenless 1 (SOS1), the RasGEF, interacts with ERα and STAT3 during embryo implantation

Estrogen accounts for several biological processes in the body; embryo implantation and pregnancy being one of the vital events. This manuscript aims to unearth the nuclear role of Son of sevenless1 (SOS1), its interaction with estrogen receptor alpha (ERα), and signal transducer and activator of transcription 3 (STAT3) in the uterine nucleus during embryo implantation. SOS1, a critical cytoplasmic linker between receptor tyrosine kinase and rat sarcoma virus signaling, translocates into the nucleus via its bipartite nuclear localization signal (NLS) during the 'window of implantation' in pregnant mice. SOS1 associates with chromatin, interacts with histones, and shows intrinsic histone acetyltransferase (HAT) activity specifically acetylating lysine 16 (K16) residue of histone H4. SOS1 is a coactivator of STAT3 and a co-repressor of ERα. SOS1 creates a partial mesenchymal-epithelial transition by acting as a transcriptional modulator. Finally, our phylogenetic tree reveals that the two bipartite NLS surface in reptiles and the second acetyl coenzymeA (CoA) (RDNGPG) important for HAT activity emerges in mammals. Thus, SOS1 has evolved into a moonlighting protein, the special class of multi-tasking proteins, by virtue of its newly identified nuclear functions in addition to its previously known cytoplasmic function.

AKTIP loss is enriched in ERα-positive breast cancer for tumorigenesis and confers endocrine resistance

Recurrent deletion of 16q12.2 is observed in luminal breast cancer, yet the causal genomic alterations in this region are largely unknown. In this study, we identify that loss of AKTIP, which is located on 16q12.2, drives tumorigenesis of estrogen receptor alpha (ERα)-positive, but not ERα-negative, breast cancer cells and is associated with poor prognosis of patients with ERα-positive breast cancer. Intriguingly, AKTIP-depleted tumors have increased ERα protein level and activity. Cullin-associated and neddylation-dissociated protein 1 (CAND1), which regulates the cullin-RING E3 ubiquitin ligases, protects ERα from cullin 2-dependent proteasomal degradation. Apart from ERα signaling, AKTIP loss triggers JAK2-STAT3 activation, which provides an alternative survival signal when ERα is inhibited. AKTIP-depleted MCF7 cells and ERα-positive patient-derived organoids are more resistant to ERα antagonists. Importantly, the resistance can be overcome by co-inhibition of JAK2/STAT3. Together, our results highlight the subtype-specific functional consequences of AKTIP loss and provide a mechanistic explanation for the enriched AKTIP copy-number loss in ERα-positive breast cancer.

Efficacy Evaluation of Inflammatory Mediators in the Treatment of Multiple Myeloma with Daratumumab

Objective

This study aimed to investigate the regulatory ability and clinical therapeutic effect of daratumumab on inflammatory mediators in patients with multiple myeloma.

Method

The Multiple Myeloma Public Genetic Data Array download GSE125361 dataset was collected. The GO analysis and KEGG analysis were performed on the differential genes to elucidate the multiple myeloma cytokine-related gene pathways. Daratumumab is a CD38 monoclonal antibody used to treat multiple myeloma. Patients with newly diagnosed multiple myeloma were treated with monoclonal antibodies containing CD38, and the control group was treated with a regimen without daratumumab. The serum levels of IL-2, IL-4, IL-6, IL-10, TNF-α, and IFN-γ were measured in the two groups before and after treatment and the therapeutic effects of the two groups were compared.

Result

The KEGG analysis showed that the Th17 cell differentiation, apoptosis, and cytokine-cytokine receptor interaction pathways were differentially expressed in multiple myeloma. The expression levels of serum IL-2, IL-6, IL-10, and TNF-α in patients in the daratumumab group were lower than those in the control group after chemotherapy. The overall effective rate of patients treated with daratumumab after chemotherapy was higher than that of the control group.

Conclusion

Daratumumab can effectively improve the levels of IL-2, IL-6, IL-10, and TNF-α in patients with multiple myeloma and improve the therapeutic effect.

tRNA Derivatives in Multiple Myeloma: Investigation of the Potential Value of a tRNA-Derived Molecular Signature

Multiple myeloma (MM) is a hematologic malignancy arising from the clonal proliferation of malignant plasma cells. tRNA-derived RNA fragments (tRFs) constitute a class of small non-coding RNAs, deriving from specific enzymatic cleavage of tRNAs. To the best of our knowledge, this is one of few studies to uncover the potential clinical significance of tRFs in MM. Total RNA was extracted from CD138+ plasma cells of MM and smoldering MM patients, and in vitro polyadenylated. First-strand cDNA synthesis was performed, priming from an oligo-dT-adaptor sequence. Next, real-time quantitative PCR (qPCR) assays were developed for the quantification of six tRFs. Biostatistical analysis was performed to assess the results and in silico analysis was conducted to predict the function of one of the tRFs. Our results showed that elevated levels of five out of six tRFs are indicators of favorable prognosis in MM, predicting prolonged overall survival (OS), while two of them constitute potential molecular biomarkers of favorable prognosis in terms of disease progression. Moreover, three tRFs could be used as surrogate prognostic biomarkers along with the R-ISS staging system to predict OS. In conclusion, tRFs show molecular biomarker utility in MM, while their mechanisms of function merit further investigation.

Targeting the IL-6/STAT3 Signalling Cascade to Reverse Tamoxifen Resistance in Estrogen Receptor Positive Breast Cancer

Simple Summary

This study identifies the molecular mechanisms through which BQ323636.1 can enhance IL-6 and IL-6R expression, which leads to the activation of STAT3 and the development of tamoxifen resistance in ER+ breast cancer. We demonstrated a statistically significant association of IL-6R with tamoxifen resistance; patients with high IL-6R expression had poorer survival outcome. In vitro and in vivo studies confirmed that targeting IL-6R with Tocilizumab reduced tamoxifen resistance, providing the basis for potential use for disease management

Abstract

Breast cancer is the most common female cancer. About 70% of breast cancer patients are estrogen receptor α (ERα) positive (ER+) with tamoxifen being the most commonly used anti-endocrine therapy. However, up to 50% of patients who receive tamoxifen suffer recurrence. We previously identified BQ323636.1 (BQ), a novel splice variant of NCOR2, can robustly predict tamoxifen resistance in ER+ primary breast cancer. Here we show that BQ can enhance IL-6/STAT3 signalling. We demonstrated that through interfering with NCOR2 suppressive activity, BQ favours the binding of ER to IL-6 promoter and the binding of NF-ĸB to IL-6 receptor (IL-6R) promoter, leading to the up-regulation of both IL-6 and IL-6R and thus the activation of STAT3. Knockdown of IL-6R could compromise tamoxifen resistance mediated by BQ. Furthermore, Tocilizumab (TCZ), an antibody that binds to IL-6R, could effectively reverse tamoxifen resistance both in vitro and in vivo. Analysis of clinical breast cancer samples confirmed that IL-6R expression was significantly associated with BQ expression and tamoxifen resistance in primary breast cancer, with high IL-6R expression correlating with poorer survival. Multivariate Cox-regression analysis confirmed that high IL-6R expression remained significantly associated with poor overall as well as disease-specific survival in ER+ breast cancer.

A roadmap to target interleukin-6 in osteoarthritis

Joint inflammation is present in the majority of OA patients and pro-inflammatory mediators, such as IL-6, are actively involved in disease progression. Increased levels of IL-6 in serum or synovial fluid from OA patients correlate with disease incidence and severity, with IL-6 playing a pivotal role in the development of cartilage pathology, e.g. via induction of matrix-degrading enzymes. However, IL-6 also increases expression of anti-catabolic factors, suggesting a protective role. Until now, this dual role of IL-6 is incompletely understood and may be caused by differential effects of IL-6 classic vs trans-signalling. Here, we review current evidence regarding the role of IL-6 classic- and trans-signalling in local joint pathology of cartilage, synovium and bone. Furthermore, we discuss targeting of IL-6 in experimental OA models and provide future perspective for OA treatment by evaluating currently available IL-6 targeting strategies.

Mercury induces nuclear estrogen receptors to act as vasoconstrictors promoting endothelial denudation via the PI3K/Akt signaling pathway

Cardiovascular diseases (CVD) are more frequent among postmenopausal women due to the decline of estrogen concentration in plasma. However, the role of the vascular modulator effect of estrogen is controversial, since it occurs both in physiological and pathological conditions, increasing or reducing vascular reactivity. As mercury is widely associated with the development of CVD, we investigated putative hazardous effects on the mechanisms that modulate vascular reactivity in aortic rings of female Wistar rats promoted by acute mercury exposure. Mercury increased vascular reactivity and oxidative stress possibly due to NADPH oxidase participation, increased production of cyclooxygenase-2 (COX-2) and thromboxane A₂ (TXA₂) formation. The metal also induced endothelial denudation in the aorta by reducing the bioavailability of nitric oxide (NO) and enhancing the activity of the PI3K/Akt signaling pathway. Mercury exposure also induced nuclear estrogen receptors (ERα, ERβ) to act as vasoconstrictors. Our findings suggest that mercury might increase the chances of developing cardiovascular diseases in females and should be considered an important environmental risk factor.

STAT3: A Promising Therapeutic Target in Multiple Myeloma

Multiple myeloma (MM) is an incurable plasma cell malignancy for which novel treatment options are required. Signal Transducer and Activator of Transcription 3 (STAT3) overexpression in MM appears to be mediated by a variety of factors including interleukin-6 signaling and downregulation of Src homology phosphatase-1 (SHP-1). STAT3 overexpression in MM is associated with an adverse prognosis and may play a role in microenvironment-dependent treatment resistance. In addition to its pro-proliferative role, STAT3 upregulates anti-apoptotic proteins and leads to microRNA dysregulation in MM. Phosphatase of regenerating liver 3 (PRL-3) is an oncogenic phosphatase which is upregulated by STAT3. PRL-3 itself promotes STAT-3 phosphorylation resulting in a positive feedback loop. PRL-3 is overexpressed in a subset of MM patients and may cooperate with STAT3 to promote survival of MM cells. Indirectly targeting STAT3 via JAK (janus associated kinase) inhibition has shown promise in early clinical trials. Specific inhibitors of STAT3 showed in vitro efficacy but have failed in clinical trials while several STAT3 inhibitors derived from herbs have been shown to induce apoptosis of MM cells in vitro. Optimising the pharmacokinetic profiles of novel STAT3 inhibitors and identifying how best to combine these agents with existing anti-myeloma therapy are key questions to be addressed in future clinical trials.

MUC1/KL-6 expression confers an aggressive phenotype upon myeloma cells

The sialic glycoprotein, MUC1, is known to be involved in the pathogenesis of various types of cancers. KL-6 is one of the surface antigens of MUC1 and also a marker of interstitial pneumonitis. A fraction of patients with myeloma (3.9%) have elevated serum KL-6 levels without any evidence of interstitial pneumonitis and their myeloma cells have high MUC1 expression. We established a myeloma cell line designated EMM1 from a patient with multiple myeloma accompanied with elevated serum KL-6. EMM1 cells expressed high levels of MUC1 compared with other myeloma cell lines. Knockdown of MUC1 in EMM1 cells induced cell cycle arrest during S phase and apoptosis, suggesting that the MUC1 expression is involved in accelerated growth of EMM1 cells. RNA-seq analysis suggests that MUC1 expression activates k-ras and TNFα-induced NFκB pathways in EMM1 cells. We injected EMM1 cells subcutaneously into Rag2^-/-Jak3^-/- Balb/c mice to establish a mouse xenograft model. These mice had aggressive tumor growth that was accompanied by high serum KL-6 levels. In addition, MUC1 knockdown in EMM1 cells led to inhibited tumor growth. These findings demonstrate that MUC1 serves as a potential target for developing drugs for treatment of patients with KL-6⁺ myeloma, and EMM1 cells and EMM1-engrafted mice are useful tools for the development of such novel agents.

Repurposing Antiestrogens for Tumor Immunotherapy

Svoronos and colleagues observed estrogen receptor alpha-positive cells in the tumor stroma of patients with ovarian cancer that appeared to be independent of both the tumor's estrogen receptor status and tumor type. These cells were identified as immunosuppressive myeloid-derived suppressor cells (MDSC) and could be targeted by antiestrogen therapy, thereby leading to the hypothesis that endocrine therapy when combined with immunotherapy may provide a potential therapeutic benefit by helping to reduce immunosuppressive MDSCs. Cancer Discov; 7(1); 17-9. ©2017 AACRSee related article by Svoronos et al., 72.

Ovarian function's role during cancer cachexia progression in the female mouse

Cachexia is a debilitating condition that occurs with chronic disease, including cancer; our research has shown that some regulation of cancer cachexia progression is affected by sex differences. The Apc^Min/+ mouse is genetically predisposed to develop intestinal tumors; IL-6 signaling and hypogonadism are associated with cachexia severity in the male. This relationship in the female warrants further investigation, as we have shown that the ability of IL-6 to induce cachexia differs between the sexes. Since ovarian reproductive function relies on a complex system of endocrine signaling to affect whole body homeostasis, we examined the relationship between ovarian reproductive function and progression of cancer cachexia in the female Apc^Min/+ mouse. Our study of ovarian reproductive function in female Apc^Min/+ mice showed disease-related cessation of estrous cycling (acyclicity) in 38% of mice. Acyclicity, including morphological and functional losses and enhanced muscle inflammatory gene expression, was associated with severe cachexia. Interestingly, ovariectomy rescued body weight and muscle mass and function but increased muscle sensitivity to systemic IL-6 overexpression. In conclusion, our results provide evidence for a relationship between ovarian reproductive function and cachexia progression in female Apc^Min/+ mice.

Androgen receptor expression in mantle cell lymphoma: Potential novel therapeutic implications

Mantle cell lymphoma (MCL) affects approximately 4500 patients/year in the US and demonstrates a male to female ratio of approximately 4:1. While the pathobiology underlying this ratio is unknown, the hematopoietic system is characterized by sex-related differences in androgen receptor (AR) expression, leading us to hypothesize that the male-biased incidence of MCL may reflect sex-related differences in AR signaling during MCL lymphomagenesis. To explore the AR axis in MCL, we evaluated AR expression in MCL cell lines and human tumors, and tested the impact of androgen pathway inhibition on MCL proliferation. AR transcript levels ranged up to ~26 fold higher in MCL lines vs non-MCL NHL lines (p = 0.006) and were correlated with expression of the canonical AR-regulated gene, prostate-specific antigen (PSA; r = 0.715, p = 0.001), consistent with functional AR activity. Patient-derived MCL samples demonstrated a range of AR expression. Treatment of four different MCL lines with the potent AR antagonist enzalutamide demonstrated suppression of proliferation across both male and female-derived cell lines. These data suggest androgen-axis blockade may represent a novel therapeutic modality in MCL. This novel treatment approach is currently under investigation in a phase II clinical trial of AR inhibition in patients with relapsed/refractory MCL.

Chromosome 8p tumor suppressor genes SH2D4A and SORBS3 cooperate to inhibit interleukin-6 signaling in hepatocellular carcinoma

Several chronic inflammatory liver diseases, e.g., chronic hepatitis B or C viral infection and steatohepatitis, have been shown to predispose to the development of hepatocellular carcinoma (HCC). In patients with chronic liver disease, interleukin-6 (IL-6) serum levels are elevated and increase even more when HCC develops. However, the impact and regulatory mechanisms of IL-6 signaling during hepatocarcinogenesis are still poorly defined. Here, we show that gene expression profiles of patients with chromosome 8p loss correlate with increased IL-6 signaling. In addition, the chromosome 8p tumor suppressor genes Src homology 2 domain containing 4A (SH2D4A) and Sorbin and Src homology 3 domain containing 3 (SORBS3) together exerted greater inhibition of cell growth and clonogenicity compared to a single gene. Overexpression of SH2D4A and SORBS3 in HCC cells led to decreased IL-6 target gene expression and reduced signal transducer and activator of transcription 3 (STAT3) signaling. In situ and in vitro coimmunoprecipitation assays revealed that SH2D4A directly interacts with STAT3, thereby retaining STAT3 in the cytoplasm and inhibiting STAT3 transcriptional activity. On the other hand, SORBS3 coactivated estrogen receptor α signaling, leading indirectly to repression of STAT3 signaling. In human HCC tissues, SH2D4A was positively associated with infiltrating regulatory and cytotoxic T-cell populations, suggesting distinct immunophenotypes in HCC subgroups with chromosome 8p loss. Thus, the genetically linked tumor suppressors SH2D4A and SORBS3 functionally cooperate to inhibit STAT3 signaling in HCC.

CONCLUSION

The chromosome 8p tumor suppressor genes SORBS3 and SH2D4A are physically and functionally linked and provide a molecular mechanism of inhibiting STAT3-mediated IL-6 signaling in HCC cells. (Hepatology 2016;64:828-842).

Prognostic value of protein inhibitor of activated STAT3 in breast cancer patients receiving hormone therapy

Background

Deregulated signal transducer and activator of transcription 3 (STAT3) signaling has been well documented in certain cancers. Alterations in specific negative regulators, such as protein inhibitor of activated STAT3 (PIAS3), may contribute to cancer development.

Methods

The expression of total PIAS3 was determined in 100 paired cancerous and non-cancerous breast tissues by immunoblotting and was statistically analyzed along with the clinicopathological characteristics and overall survival of the patients. XTT, immunoblotting, and chromatin immunoprecipitation (Chip) were used to examine the biological effect of PIAS3 in breast cancer cells.

Results

Hormone therapy failed to improve the overall survival in patients presenting with increased PIAS3 expression. Ectopic PIAS3 overexpression increased the proliferation and expression of cyclin D1 in estrogen receptor (ER)-positive MCF-7 and T47D cells, but decreased those in ER-negative MDA-MB-231 and SKBR3 cells. Furthermore, PIAS3 overexpression attenuated cytotoxicity of tamoxifen and increased proliferation and cyclin D1 expression in MCF-7 cells. PIAS3 also decreased the binding of itself on the cyclin D1 promoter and this decreased binding was not affected by tamoxifen.

Conclusion

PIAS3 may serve as a biomarker for predicting hormone therapy stratification, although it is limited to those breast cancer patients receiving hormone therapy

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2063-1) contains supplementary material, which is available to authorized users.

L-carnitine ameliorates the liver inflammatory response by regulating carnitine palmitoyltransferase I-dependent PPARγ signaling

The liver is crucial for systemic inflammation in cancer cachexia. Previous studies have shown that L-carnitine, as the key regulator of lipid metabolism, exerts an anti-inflammatory effect in several diseases, and ameliorates the symptoms of cachexia by regulating the expression and activity of carnitine palmitoyltransferase (CPT) in the liver. However, the effect of L-carnitine on the liver inflammatory response in cancer cachexia remains to be elucidated. The aim of the present study was to examine the role of the CPT I-dependent peroxisome proliferator-activated receptor (PPAR)γ signaling pathway in the ameliorative effect of L-carnitine on the liver inflammatory response. This was investigated in a colon-26 tumor-bearing mouse model with cancer cachexia. Liver sections were immunohistochemically analyzed, and mRNA and protein levels of representative molecules of the CPT-associated PPARγ signaling pathway were assessed using PCR and western blot analysis, respectively. The results showed that oral administration of L-carnitine in these mice improved hepatocyte necrosis, liver cell cord derangement and hydropic or fatty degeneration of the liver cells in the liver tissues, decreased serum levels of malondialdehyde, increased serum levels of superoxide dismutase and glutathione peroxidase, and elevated the expression levels of PPARα and PPARγ at the mRNA and protein levels. These changes induced by L-carnitine were reversed by treatment with etomoxir, an inhibitor of CPT I. The inhibitory effect of L-carnitine on the increased expression level of nuclear factor (NF)-κB p65 in the peripheral blood mononuclear cells was markedly weakened by GW9662, a selective inhibitor of PPAR-γ. GW9662 also eliminated the inhibitory effect of L-carnitine on the expression of cyclooxygenase-2 (Cox-2) in the liver, and on the serum expression levels of pro-inflammatory prostaglandin E2, C-reactive protein, tumor necrosis factor-α and interleukin-6 in the cancer cachexia model mice. This reversing effect of GW9662 on L-carnitine was restored by pyrrolidine dithiocarbamate, a specific inhibitor of NF-κB signaling. Taken together, these results demonstrated that L-carnitine ameliorated liver inflammation and serum pro-inflammatory markers in cancer cachexia through regulating CPT I-dependent PPARγ signaling, including the downstream molecules of NF-κB p65 and Cox-2.

Estrogenic endocrine disruptors: Molecular mechanisms of action

A comprehensive summary of more than 450 estrogenic chemicals including estrogenic endocrine disruptors is provided here to understand the complex and profound impact of estrogen action. First, estrogenic chemicals are categorized by structure as well as their applications, usage and effects. Second, estrogenic signaling is examined by the molecular mechanism based on the receptors, signaling pathways, crosstalk/bypassing and autocrine/paracrine/homeostatic networks involved in the signaling. Third, evaluation of estrogen action is discussed by focusing on the technologies and protocols of the assays for assessing estrogenicity. Understanding the molecular mechanisms of estrogen action is important to assess the action of endocrine disruptors and will be used for risk management based on pathway-based toxicity testing.

Changing trends in prognostic factors for patients with multiple myeloma after autologous stem cell transplantation during the immunomodulator drug/proteasome inhibitor era

We evaluated the clinical significance of prognostic factors including the International Staging System (ISS) and modified European Group for Blood and Marrow Transplantation response criteria in 1650 Japanese patients with multiple myeloma (MM) who underwent upfront single autologous stem cell transplantation (ASCT). We categorized patients into two treatment cohorts: pre-novel agent era (1995–2006) and novel agent era (2008–2011). The combined percentage of pre-ASCT complete response and very good partial response cases (463 of 988, 47%) significantly increased during the novel agent era compared with the pre-novel agent era (164 of 527, 31%; P < 0.0001). The 2-year overall survival (OS) rate of 87% during the novel agent era was a significant improvement relative to that of 82% during the pre-novel agent era (P = 0.019). Although significant differences in OS were found among ISS stages during the pre-novel agent era, no significant difference was observed between ISS I and II (P = 0.107) during the novel agent era. The factors independently associated with a superior OS were female gender (P = 0.002), a good performance status (P = 0.024), lower ISS (P < 0.001), pre-ASCT response at least partial response (P < 0.001) and ASCT during the novel agent era (P = 0.017). These results indicate that the response rate and OS were significantly improved, and the ISS could not clearly stratify the prognoses of Japanese patients with MM who underwent upfront single ASCT during the novel agent era.

Sex differences in the relationship of IL-6 signaling to cancer cachexia progression

A devastating aspect of cancer cachexia is severe loss of muscle and fat mass. Though cachexia occurs in both sexes, it is not well-defined in the female. The Apc(Min/+) mouse is genetically predisposed to develop intestinal tumors; circulating IL-6 is a critical regulator of cancer cachexia in the male Apc(Min/+) mouse. The purpose of this study was to examine the relationship between IL-6 signaling and cachexia progression in the female Apc(Min/+) mouse. Male and female Apc(Min/+) mice were examined during the initiation and progression of cachexia. Another group of females had IL-6 overexpressed between 12 and 14 weeks or 15-18 weeks of age to determine whether IL-6 could induce cachexia. Cachectic female Apc(Min/+) mice lost body weight, muscle mass, and fat mass; increased muscle IL-6 mRNA expression was associated with these changes, but circulating IL-6 levels were not. Circulating IL-6 levels did not correlate with downstream signaling in muscle in the female. Muscle IL-6r mRNA expression and SOCS3 mRNA expression as well as muscle IL-6r protein and STAT3 phosphorylation increased with severe cachexia in both sexes. Muscle SOCS3 protein increased in cachectic females but decreased in cachectic males. IL-6 overexpression did not affect cachexia progression in female Apc(Min/+) mice. Our results indicate that female Apc(Min/+) mice undergo cachexia progression that is at least initially IL-6-independent. Future studies in the female will need to determine mechanisms underlying regulation of IL-6 response and cachexia induction.

17β-Estradiol inhibition of IL-6-Src and Cas and paxillin pathway suppresses human mesenchymal stem cells-mediated gastric cancer cell motility

Epidemiological studies demonstrate that the incidence and mortality of gastric cancer in women are lower than in men worldwide. Many studies have reported the delayed menopause and hormone replacement therapy are associated with a reduced risk for gastric cancer. It has been reported that endogenous estrogen lowers gastric cancer incidence in women, and cancer patients treated with estrogens have a lower subsequent risk of gastric cancer. It has been reported that estrogen decreases the progression of gastric cancer by inhibiting erbB-2 oncogene expression. Overexpression of estrogen receptor might inhibit the proliferation and invasion of MKN28 gastric cancer cells. Accumulating evidence suggests that bone marrow mesenchymal stem cells contribute to the progression of gastric cancer. However, it is unknown if 17β-estradiol (E2) treatment is sufficient to inhibit human bone marrow mesenchymal stem cells (HBMMSCs)-mediated cell motility in human gastric cancer cells. The results from human cytokine arrays have shown that HBMMSCs notably secrete interleukin 6 (IL-6) protein. Administration of IL-6-specific neutralizing antibody significantly inhibits HBMMSCs-mediated motility activity in human gastric cancer cells. Treatment of recombinant IL-6 soluble protein confirmed the role of IL-6 in mediating HBMMSCs-upregulated cell motility. IL-6 mainly upregulates motility activity via activation of Src signaling pathway in human gastric cancer cells. We further observed that E2 treatment inhibits HBMMSCs-induced cellular motility via suppressing the activation of IL-6-Src/Cas/paxillin signaling pathway in human gastric cancer cells. Collectively, these results suggest that E2 treatment significantly inhibits HBMMSCs-induced cellular motility in human gastric cancer cells.

Transcription Factor STAT3 as a Novel Molecular Target for Cancer Prevention

Signal Transducers and Activators of Transcription (STATs) are a family of transcription factors that regulate cell proliferation, differentiation, apoptosis, immune and inflammatory responses, and angiogenesis. Cumulative evidence has established that STAT3 has a critical role in the development of multiple cancer types. Because it is constitutively activated during disease progression and metastasis in a variety of cancers, STAT3 has promise as a drug target for cancer therapeutics. Recently, STAT3 was found to have an important role in maintaining cancer stem cells in vitro and in mouse tumor models, suggesting STAT3 is integrally involved in tumor initiation, progression and maintenance. STAT3 has been traditionally considered as nontargetable or undruggable, and the lag in developing effective STAT3 inhibitors contributes to the current lack of FDA-approved STAT3 inhibitors. Recent advances in cancer biology and drug discovery efforts have shed light on targeting STAT3 globally and/or specifically for cancer therapy. In this review, we summarize current literature and discuss the potential importance of STAT3 as a novel target for cancer prevention and of STAT3 inhibitors as effective chemopreventive agents.

STAT3 and MCL-1 associate to cause a mesenchymal epithelial transition

Embryo implantation is effected by a myriad of signaling cascades acting on the embryo-endometrium axis. Here we show, by using MALDI TOF analysis, far-western analysis and colocalization and co-transfection studies, that STAT3 and MCL-1 are interacting partners during embryo implantation. We show in vitro that the interaction between the two endogenous proteins is strongly regulated by estrogen and progesterone. Implantation, pregnancy and embryogenesis are distinct from any other process in the body, with extensive, but controlled, proliferation, cell migration, apoptosis, cell invasion and differentiation. Cellular plasticity is vital during the early stages of development for morphogenesis and organ homeostasis, effecting the epithelial to mesenchymal transition (EMT) and, the reverse process, mesenchymal to epithelial transition (MET). STAT3 functionally associates with MCL-1 in the mammalian breast cancer cell line MCF7 that overexpresses STAT3 and MCL-1, which leads to an increased rate of apoptosis and decreased cellular invasion, disrupting the EMT. Association of MCL-1 with STAT3 modulates the normal, anti-apoptotic, activity of MCL-1, resulting in pro-apoptotic effects. Studying the impact of the association of STAT3 with MCL-1 on MET could lead to an enhanced understanding of pregnancy and infertility, and also metastatic tumors.

Identification of novel miR-21 target proteins in multiple myeloma cells by quantitative proteomics

Substantial evidence indicates that microRNA-21 (miR-21) is a key oncomiR in carcinogenesis and is significantly elevated in multiple myeloma (MM). In this study, we explored the role of miR-21 in human MM cells and searched for miR-21 targets. By knocking down the expression of endogenous miR-21 in U266 myeloma cells, we observed reduced growth, an arrested cell cycle, and increased apoptosis. To further understand its molecular mechanism in the pathogenesis of MM, we employed a SILAC (stable isotope labeling by amino acids in cell culture)-based quantitative proteomic strategy to systematically identify potential targets of miR-21. In total, we found that the expression of 178 proteins was up-regulated significantly by miR-21 inhibition, implying that they could be potential targets of miR-21. Among these, the protein inhibitor of activated STAT3 (PIAS3) was confirmed as a direct miR-21 target by Western blotting and reporter gene assays. We further demonstrated that miR-21 enhances the STAT3-dependent signal pathway by inhibiting the function of PIAS3 and that down-regulation of PIAS3 contributes to the oncogenic function of miR-21. This elucidation of the role of PIAS3 in the miR-21-STAT3 positive regulatory loop not only may shed light on the molecular basis of the biological effects of miR-21 observed in MM cells but also has direct implications for the development of novel anti-MM therapeutic strategies.

QUICK identification and SPR validation of signal transducers and activators of transcription 3 (Stat3) interacting proteins

Signal transducers and activators of transcription 3 (Stat3) has been reported to be involved in the pathogenesis of various human diseases and is constitutively active in human multiple myeloma (MM) U266 cells. The Stat3-regulated mechanisms involved in these processes, however, are not fully defined. To further understand the regulation of Stat3 activity, we performed a systematic proteomic analysis of Stat3 interacting proteins in U266 cells. This analysis, termed quantitative immunoprecipitation combined with knockdown (QUICK), combines RNAi, stable isotope labeling with amino acids in cell culture (SILAC), immunoprecipitation, and quantitative MS. As a result, quantitative mass spectrometry analysis allowed us to distinguish specific Stat3 interacting proteins from background proteins and led to the identification of a total of 38 proteins. Three Stat3 interacting proteins - 14-3-3ζ, PRKCB and Hsp90 - were further confirmed by reciprocal co-immunoprecipitations and surface plasmon resonance (SPR) analysis. Our results therefore not only uncover a number of Stat3 interacting proteins that possess a variety of cellular functions, but also provide new insight into the mechanisms that regulate Stat3 activity and function in MM cells.

Inhibition of Bcl3 gene expression mediates the anti-proliferative action of estrogen in pituitary lactotrophs in primary culture

In addition to their well-known stimulatory action, estrogens have an anti-proliferative effect. The present study was undertaken to investigate the mechanism by which 17β-estradiol (E2) inhibits insulin-like growth factor-1 (IGF-1)-induced proliferation in vitro in the rat pituitary lactotroph, a typical estrogen-responsive cell. E2 treatment of pituitary cells did not change levels of IGF-1-induced phosphorylation of proliferation-related protein kinases such as Erk1/2 and Akt. We performed global gene expression profiling by DNA microarray analysis and identified 177 genes regulated by E2 in the presence of IGF-1. These results were verified by quantitative real time PCR. The estrogen-regulated genes included several NFκB family related genes. As pharmacological inhibition of the NFκB pathway blocked IGF-1-induced lactotroph proliferation, we chose to investigate whether one NFκB pathway gene, Bcl3, was involved in the anti-proliferative action of E2. RNA interference-mediated knockdown of Bcl3 expression attenuated IGF-1-induced lactotroph proliferation. Even minimal induced overexpression of Bcl3 blocked the anti-proliferative action of E2. In contrast, Nfkb2, another E2-downregulated protein, required maximal overexpression to block the anti-proliferative action of E2. These results suggest that inhibition of Bcl3 expression is involved in the anti-proliferative action of estrogens in pituitary lactotrophs in culture.

A Role for PPARgamma in the Regulation of Cytokines in Immune Cells and Cancer

Peroxisome proliferator-activated receptor γ (PPARγ) is a ligand-activated transcription factor and a member of the nuclear receptor superfamily. PPARγ and its ligands appear to serve diverse biological functions. In addition to the well-studied effects of PPARγ on metabolism and cellular differentiation, abundant evidence suggests that PPARγ is an important regulator of the immune system and cancers. Since cytokines are not only key modulators of inflammation with pro- and anti-inflammatory functions but they also can either stimulate or inhibit tumor growth and progression, this review summarizes the role for PPARγ in the regulation of cytokine production and cytokine-mediated signal transduction pathways in immune cells and cancer.

Clinical significance of interleukin (IL)-6 in cancer metastasis to bone: potential of anti-IL-6 therapies

Metastatic events to the bone occur frequently in numerous cancer types such as breast, prostate, lung, and renal carcinomas, melanoma, neuroblastoma, and multiple myeloma. Accumulating evidence suggests that the inflammatory cytokine interleukin (IL)-6 is frequently upregulated and is implicated in the ability of cancer cells to metastasize to bone. IL-6 is able to activate various cell signaling cascades that include the STAT (signal transducer and activator of transcription) pathway, the PI3K (phosphatidylinositol-3 kinase) pathway, and the MAPK (mitogen-activated protein kinase) pathway. Activation of these pathways may explain the ability of IL-6 to mediate various aspects of normal and pathogenic bone remodeling, inflammation, cell survival, proliferation, and pro-tumorigenic effects. This review article will discuss the role of IL-6: 1) in bone metabolism, 2) in cancer metastasis to bone, 3) in cancer prognosis, and 4) as potential therapies for metastatic bone cancer.

Estrogen receptor alpha pathway is involved in leptin-induced ovarian cancer cell growth

Previously, we demonstrated that leptin, a pleiotropic hormone produced by adipocytes, stimulates the growth of BG-1 ovarian cancer cells via the extracellular signal-regulated kinase signaling pathway. In this study, we further investigated the involvement of estrogen receptor (ER) pathway in the mechanism of leptin-induced ovarian cancer cell growth. Treatment with leptin (100 ng/ml) resulted in a significant increase in the cell growth of ERα-transfected OVCAR-3 and A2780 cells, whereas no significant difference was observed in ERβ-transfected cells. Downregulation of ERα using small interfering RNA completely reversed leptin-induced growth of BG-1 cells. Treatment with leptin resulted in ER transcriptional activation, i.e. nuclear localization of ER and increased expression of pS2, an estrogen-dependent gene. Luciferase reporter assay revealed that treatment of BG-1 cells with leptin (100 ng/ml) stimulated the expression of the reporter gene in the absence of estradiol (E2). To examine an involvement of Janus kinase 2/signal transducers and activators of transcription 3 (STAT-3) and phosphatidyl-inositol 3-kinase (PI3K)/Akt in leptin-induced pathway, we demonstrated that leptin increased phosphorylation of STAT-3 and Akt in BG-1 cells in a time- and dose-dependent manner. On the other hand, leptin-induced cell growth and ER transactivation were effectively blocked by specific STAT-3 inhibitor AG490 and, to a lesser extent, by PI3K inhibition. Further study with coimmunoprecipitation assay revealed that stimulation with leptin induced STAT-3 binding to ERα. Taken together, these results indicate that the stimulation of ovarian cancer cell growth by leptin involves, at least in part, ER transcriptional activation via the STAT-3 signaling pathways.

Differential interleukin-6/Stat3 signaling as a function of cellular context mediates Ras-induced transformation

Introduction

Tyrosine phosphorylated signal transducer and activator of transcription 3 (pStat3) is expressed in numerous cancers and is required for mediating tumorigenesis. Autocrine and paracrine interleukin (IL)-6 signaling is the principal mechanism by which Stat3 is persistently phosphorylated in epithelial tumors including breast, lung, colon and gastric cancer. The Ras oncogene mediates cellular transformation without evidence of pStat3 in cultured cells. However, non-tyrosine phosphorylated Stat3 was shown to function as a transcriptional activator, localize to the mitochondria and regulate ATP synthesis and mediate cell migration. Here we examined the role of Stat3 in Ras mediated transformation.

Methods

Ha-rasV12 transformed mammary epithelial cells (MCF10A-Ras) cells were transduced with a Stat3shRNA, IL-6shRNA and/or treated with inhibitors of Janus kinases (JAKs) to examine the role of the IL-6 signaling pathway in Ras mediated migration, invasion and tumorigenesis.

Results

Cellular migration, invasion, anchorage independent growth and tumorigenesis were largely abrogated in the Stat3-reduced cells compared to control cells. Analysis of MCF10A-Ras tumors revealed high levels of pStat3 and interleukin-6. Tumors derived from transgenic MMTV-K-Ras mice were also found to express pStat3 and IL-6. MCF10A-Ras cells, when grown in a three-dimensional Matrigel culture system revealed the appearance of the junctional protein E-Cadherin as a consequence of reducing Stat3 levels or inhibiting Stat3 activity. Decreasing IL-6 levels in the MCF10A-Ras cells abrogated tumorigenesis and reduced cell migration. By isolating Ras-expressing primary tumors and serially passaging these cells in two-dimensional culture led to a decrease in IL-6 and pStat3 levels with the reappearance of E-Cadherin.

Conclusions

The cellular and environmental context can lead to differential IL-6/pStat3 signaling and a dependency on this cytokine and transcription factor for migration, invasion and tumorigenesis.

The enigma of the role of protein inhibitor of activated STAT3 (PIAS3) in the immune response

Protein inhibitor of activated STAT3 (PIAS3), the main cellular inhibitor of signal transducers and activator of transcription 3 (STAT3), has been described as a modulator of DNA binding transcription factors. The exploration of the emerging roles of PIAS3 in immune regulation is a growing and fascinating field. Recent discoveries have shed new light on the key role of PIAS3 in the regulation of transcriptional activity, and on the molecular mechanism involved. These findings suggest that the known functions of this signalling molecule are merely the "tip of the iceberg". This article reviews the challenging questions regarding the link between PIAS3 and the intracellular signalling in immune cells. Some of the known functions of PIAS3 that potentially modulate key proteins in the immune system will also be discussed.

Cooperative interaction between protein inhibitor of activated signal transducer and activator of transcription-3 with epidermal growth factor receptor blockade in lung cancer

Epidermal Growth Factor Receptor (EGFR) targeting in nonsmall cell lung cancer (NSCLC) is an established treatment modality; however, it only benefits a minority of patients. STAT3 (signal transducer and activator of transcription-3) plays an important role in the oncogenic signal transduction pathway of NSCLC. Inhibition of STAT3 results in NSCLC growth inhibition and apoptosis. We have previously shown that combined inhibition of EGFR and STAT3 by small molecules resulted in improved therapeutic efficacy as compared with blocking EGFR alone. However, the STAT3 protein has a number of endogenous negative regulators including PIAS3 (Protein Inhibitor of Activated STAT3). In this study, we investigated for the first time the role of PIAS3 in modulating oncogenic EGFR-STAT3 signaling pathway in lung cancer and the anti-proliferative effect of using PIAS3 in conjunction with EGFR blockade in NSCLC. We demonstrate that PIAS3 is expressed in variable degrees in all NSCLC cells. EGF and IL-6 stimulation resulted in the association of PIAS3 with STAT3. The PIAS3/STAT3 complex then bound the STAT3 DNA binding sequence resulting in STAT3 regulated gene expression. Over-expression of PIAS3, using a PIAS3 expression construct, decreases STAT3 transcriptional activity. Furthermore, over-expression of PIAS3 consistently decreased proliferation. EGFR blockade and PIAS3 over-expression in combination had significantly greater anti-proliferative effects as compared with either EGFR blockade or PIAS3 over-expression alone. In conclusion, PIAS3 is expressed in NSCLC cell lines and its over-expression decreased STAT3 transcriptional activity, decreased proliferation of NSCLC cells and when used in conjunction with EGFR inhibitors, increased the anti-proliferative effects.

17beta-Estradiol overcomes human myeloma RPMI8226 cell suppression of growth, ALP activity, and mineralization in rat osteoblasts and improves RANKL/OPG balance in vitro

Multiple myeloma (MM) is a plasma cell malignancy characterized by a high capacity to induce osteolytic bone lesions. MM patients with osteolytic bone lesions have lower numbers of osteoblasts and decreased bone formation, which plays a critical role in the bone-destructive process. Although the mechanism of estrogen action on bone cells and myeloma cells has been widely investigated, estrogen action on bone cells in MM is unknown. In this study, the effects of the gonadal hormone 17beta-estradiol on cell growth, alkaline phosphatase (ALP) activity, mineralization capacity, and RANKL/OPG ratios in primary rat osteoblasts cultured with MM cell conditioned medium (CM) or co-cultured with RPMI8226 cells were investigated. Treatments of 10(-2) to 10 nM 17beta-estradiol reversed inhibition of proliferation and ALP activity of osteoblasts by myeloma cells in a dose-dependent manner, and 10(-2) to 1 nM 17beta-estradiol reversed inhibition of the mineralization capacity of osteoblasts by myeloma cells. In co-culture experiments with primary rat osteoblasts and myeloma cells, treatments of 10(-2) to 10 nM 17beta-estradiol down-regulated transcription and secretion of RANKL and up-regulated transcription and secretion of OPG in the osteoblasts, reversing the effects of co-cultured myeloma cells. These findings suggest that 17beta-estradiol may temper the inhibitory effects of myeloma cells on osteoblasts and improve RANKL/OPG balance, providing a new agent for treatment of bone disease in myeloma.

Estradiol acts directly on bone marrow myeloid progenitors to differentially regulate GM-CSF or Flt3 ligand-mediated dendritic cell differentiation

Estrogen receptor (ER) ligands modulate hemopoiesis and immunity in the normal state, during autoimmunity, and after infection or trauma. Dendritic cells (DC) are critical for initiation of innate and adaptive immune responses. We demonstrate, using cytokine-driven culture models of DC differentiation, that 17-beta-estradiol exerts opposing effects on differentiation mediated by GM-CSF and Flt3 ligand, the two cytokines that regulate DC differentiation in vivo. We also show that estradiol acts on the same highly purified Flt3+ myeloid progenitors (MP) to differentially regulate the DC differentiation in each model. In GM-CSF-supplemented cultures initiated from MP, physiological amounts of estradiol promoted differentiation of Langerhans-like DC. Conversely, in Flt3 ligand-supplemented cultures initiated from the same MP, estradiol inhibited cell survival in a dose-dependent manner, thereby decreasing the yield of plasmacytoid and conventional myeloid and lymphoid DC. Experiments with bone marrow cells from ER-deficient mice and the ER antagonist ICI182,780 showed that estradiol acted primarily via ERalpha to regulate DC differentiation. Thus, depending on the cytokine environment, pathways of ER signaling and cytokine receptor signaling can differentially interact in the same Flt3+ MP to regulate DC development. Because the Flt3 ligand-mediated differentiation pathway is important during homeostasis, and GM-CSF-mediated pathways are increased by inflammation, our data suggest that endogenous or pharmacological ER ligands may differentially affect DC development during homeostasis and disease, with consequent effects on DC-mediated immunity.

Estrogenic or antiestrogenic therapies for multiple myeloma?

Multiple myeloma (MM) is a common hematological malignancy which remains incurable due to both intrinsic and acquired resistance to conventional or more novel drugs. Estrogenic and antiestrogenic compounds are very promising drugs for the treatment of MM. Indeed, they inhibit cell proliferation in vitro. They block cell cycle and/or induce apoptosis even in drug-resistant MM cells but not normal B cells. They interfere with survival pathways often deregulated in myelomas. They co-operate with conventional drugs to enhance apoptosis or to overcome resistance. In vivo, they act also on tumoral angiogenesis in xenograft models. As a whole, they possess all the criteria which render them attractive for a new therapeutic strategy. Importantly, they are well-tolerated at the doses tested in vitro or in vivo, encouraging the rapid onset of critical trials.

Inhibition of adhesive interaction between multiple myeloma and bone marrow stromal cells by PPARgamma cross talk with NF-kappaB and C/EBP

Binding of multiple myeloma (MM) cells to bone marrow stromal cells (BMSCs) triggers expression of adhesive molecules and secretion of interleukin-6 (IL-6), promoting MM cell growth, survival, drug resistance, and migration, which highlights the possibility of developing and validating novel anti-MM therapeutic strategies targeting MM cells-host BMSC interactions and their sequelae. Recently, we have found that expression of the peroxisome proliferator-activated receptor gamma (PPARgamma) and its ligands can potently inhibit IL-6-regulated MM cell growth. Here we demonstrate that PPARgamma agonists 15-d-PGJ2 and troglitazone significantly suppress cell-cell adhesive events, including expression of adhesion molecules and IL-6 secretion from BMSCs triggered by adhesion of MM cells, as well as overcome drug resistance by a PPARgamma-dependent mechanism. The synthetic and natural PPARgamma agonists have diverging and overlapping mechanisms blocking transactivation of transcription factors NF-kappaB and 5'-CCAAT/enhancer-binding protein beta (C/EBPbeta). Both 15-d-PGJ2 and troglitazone blocked C/EBPbeta transcriptional activity by forming PPARgamma complexes with C/EBPbeta. 15-d-PGJ2 and troglitazone also blocked NF-kappaB activation by recruiting the coactivator PGC-1 from p65/p50 complexes. In addition, 15-d-PGJ2 had a non-PPARgamma-dependent effect by inactivation of phosphorylation of IKK and IkappaB. These studies provide the framework for PPARgamma-based pharmacological strategies targeting adhesive interactions of MM cells with the bone marrow microenvironment.

Patterns of survival in multiple myeloma: a population-based study of patients diagnosed in Sweden from 1973 to 2003

PURPOSE

To define patterns of survival among all multiple myeloma (MM) patients diagnosed in Sweden during a 30-year period.

PATIENTS AND METHODS

A total of 14,381 MM patients (7,643 males; 6,738 females) were diagnosed in Sweden from 1973 to 2003 (median age, 69.9 years; range 19 to 101 years). Patients were categorized into six age categories and four calendar periods (1973 to 1979, 1980 to 1986, 1987 to 1993, and 1994 to 2003). We computed relative survival ratios (RSRs) as measures of patient survival.

RESULTS

One-year survival improved (P < .001) over time in all age groups and RSRs were 0.73, 0.78, 0.80, and 0.82 for the four calendar periods; however, improvement in 5-year (P < .001) and 10-year (P < .001) RSR was restricted to patients younger than 70 years and younger than 60 years, respectively. For the first time, in analyses restricted to MM patients diagnosed at age younger than 60 years, we found a 29% (P < .001) reduced 10-year mortality in the last calendar period (1994 to 2003) compared with the preceding calendar period (1987 to 1993). Females with MM had a 3% (P = .024) lower excess mortality than males.

CONCLUSION

One-year MM survival has increased for all age groups during the last decades; 5-year and 10-year MM survival has increased in younger patients (younger than 60 to 70 years). High-dose melphalan with subsequent autologous stem-cell transplantation, thalidomide, and a continuous improvement in supportive care measures are probably the most important factors contributing to this finding. New effective agents with a more favorable toxicity profile are needed to improve survival further, particularly in the elderly.

Targeting signal-transducer-and-activator-of-transcription-3 for prevention and therapy of cancer: modern target but ancient solution

Recent evidence indicates a convergence of molecular targets for both prevention and therapy of cancer. Signal-transducer-and-activator-of-transcription-3 (STAT3), a member of a family of six different transcription factors, is closely linked with tumorigenesis. Its role in cancer is indicated by numerous avenues of evidence, including the following: STAT3 is constitutively active in tumor cells; STAT3 is activated by growth factors (e.g., EGF, TGF-alpha, IL-6, hepatocyte growth factor) and oncogenic kinases (e.g., Src); STAT3 regulates the expression of genes that mediate proliferation (e.g., c-myc and cyclin D1), suppress apoptosis (e.g., Bcl-x(L) and survivin), or promote angiogenesis (e.g, VEGF); STAT3 activation has been linked with chemoresistance and radioresistance; and chemopreventive agents have been shown to suppress STAT3 activation. Thus inhibitors of STAT3 activation have potential for both prevention and therapy of cancer. Besides small peptides and oligonucleotides, numerous small molecules have been identified as blockers of STAT3 activation, including synthetic molecules (e.g., AG 490, decoy peptides, and oligonucleotides) and plant polyphenols (e.g., curcumin, resveratrol, flavopiridol, indirubin, magnolol, piceatannol, parthenolide, EGCG, and cucurbitacin). This article discusses these aspects of STAT3 in more detail.

DUSP22/LMW-DSP2 regulates estrogen receptor-alpha-mediated signaling through dephosphorylation of Ser-118

In the previous study, we demonstrated the involvement of dual specificity phosphatase 22 (DUSP22/LMW-DSP2) in regulating the leukemia inhibitory factor/interleukin-6/signal transducer and activator of transcription 3-mediated signaling pathway. In this study, we show beta-estradiol (E2)-induced DUSP22 mRNA expression in estrogen receptor alpha (ERalpha)-positive breast cancer cells, whereas E2-induced phosphorylation and activation of ERalpha was suppressed by overexpression of DUSP22 but not catalytically inactive mutants. Furthermore, small-interfering RNA-mediated reduction of DUSP22 expression enhanced ERalpha-mediated transcription and endogenous gene expression. In fact, DUSP22 associated with ERalpha in vivo and both endogenous proteins interacted in ERalpha-positive breast cancer T47D cells. These results strongly suggest that DUSP22 acts as a negative regulator of the ERalpha-mediated signaling pathway.

Risk of multiple myeloma following medication use and medical conditions: a case-control study in Connecticut women

BACKGROUND

Certain commonly used drugs and medical conditions characterized by chronic immune dysfunction and/or antigen stimulation have been suggested to affect important pathways in multiple myeloma tumor cell growth and survival. We conducted a population-based case-control study to investigate the role of medical history in the etiology of multiple myeloma among Connecticut women.

METHODS

A total of 179 incident multiple myeloma cases (21-84 years, diagnosed 1996-2002) and 691 population-based controls was included in this study. Information on medical conditions, medications, and medical radiation was obtained by in-person interviews. We calculated odds ratios (OR) as measures of relative risks using logistic regression models.

RESULTS

A reduced multiple myeloma risk was found among women who had used antilipid statin therapy [OR, 0.4; 95% confidence interval (95% CI), 0.2-0.8] or estrogen replacement therapy (OR, 0.6; 95% CI, 0.4-0.99) or who had a medical history of allergy (OR, 0.4; 95% CI, 0.3-0.7), scarlet fever (OR, 0.5; 95% CI, 0.2-0.9), or bursitis (OR, 0.4; 95% CI, 0.2-0.7). An increased risk of multiple myeloma was found among women who used prednisone (OR, 5.1; 95% CI, 1.8-14.4), insulin (OR, 3.1; 95% CI, 1.1-9.0), or gout medication (OR, 6.7; 95% CI, 1.2-38.0).

CONCLUSIONS

If our results are confirmed, mechanistic studies examining how prior use of insulin, prednisone, and, perhaps, gout medication might promote increased occurrence of multiple myeloma and how antilipid statins, estrogen replacement therapy, and certain medical conditions might protect against multiple myeloma may provide insights to the as yet unknown etiology of multiple myeloma.

Improved antitumoral properties of pure antiestrogen RU 58668-loaded liposomes in multiple myeloma

In most of multiple myeloma (MM) cells, the "pure" antiestrogen (AE) RU 58668 (RU) induced either a G1-arrest (LP-1, OPM-2, NCI-H929, U266 cells) or apoptosis (RPMI 8226 cells). In RPMI 8226 cells, RU activates a caspase-dependent cell death pathway leading to the release of cytochrome c, the decrease of the essential MM survival factor Mcl-1, the cleavage of Bid and the activation of caspases-3 and -8. Incorporation of RU in pegylated cholesterol-containing liposomes allowed a controlled RU release, improving its anti-proliferative and apoptotic effects in cells. In RPMI 8226 xenografts, i.v. injected RU-liposomes but not free RU, exhibited antitumor activity. In vivo, RU-liposomes triggered the mitochondrial death pathway, concomitantly with a down-regulation of Mcl-1 and Bid cleavage. The decrease of CD34 immunoreactivity indicated a reduction of angiogenesis. The decrease of VEGF secretion in vitro supported a direct effect of RU on angiogenesis. These pro-apoptotic and antiangiogenic effects were explained by a prolonged exposure to the drug and to the endocytosis capacity of liposomes which might increase RU uptake and bypass a membrane export of free RU. Thus, these combined enhanced activities of RU-liposomes support that such a delivery of an AE may constitute a strategy of benefit for MM treatment.

The biological functions of the versatile transcription factors STAT3 and STAT5 and new strategies for their targeted inhibition

Signal transducers and activators of transcription (STATs) comprise a unique family of transcription factors, which transmit the interactions of cytokines, hormones and growth factors with their cell surface receptors into transcriptional programs. The mechanism of STAT activation has been well-established and comprises tyrosine phosphorylation, dimerization, nuclear translocation, binding to specific DNA response elements, recruitment of co-activators or co-repressors and transcriptional induction or repression of target genes. Gene deletion, microarrays, proteomics and chromatin immunoprecipitation experiments have revealed target genes with a broad range of functions regulated by STAT3 and STAT5. In the mammary gland, STAT5-induced genes contribute mainly to the prolactin dependent lobulo-alveolar development, whereas STAT3 induced genes control apoptosis during involution. Crucial effects have also been observed in other tissues. The germ line deletion of STAT3 or STAT5 causes early embryonal or perinatal lethality in mice. STAT5 is also required for proliferation of T- and B-cells and hematopoietic stem cell self-renewal. Deregulated STAT activity is often found associated with tumorigenesis and activated STATs seem to be limiting components in tumor cells. This review summarizes the functions of STAT3 and STAT5 in different cell types and the strategies that are used to counteract their action in tumor cells.

Methylation profiling in multiple myeloma

BACKGROUND

We analysed the methylation status of a panel of 10 genes including p15, p16, DAPK, p73, VHL, E-CAD, MGMT, RARbeta, RIZ1, and ER.

METHODS

The gene promoter methylation status was studied by methylation-specific polymerase chain reaction (MSP) with primers for methylated (M-MSP) and unmethylated (U-MSP) DNA in the bone marrow of 13 patients with myeloma, and one patient with plasmacytoma.

RESULT

None of the 10 genes tested were methylated in eight normal bone marrow samples. For the positive control, the sensitivity of M-MSP ranged from 1 x 10(-2) for E-CAD and MGMT, to 1 x 10(-4) for p73. Of the eight diagnostic myeloma marrow samples, hypermethylation of p15, p16, E-CAD, DAPK and ER occurred in six (75%), four (50%), seven (87.5%), eight (100%), and six (75%) patients. Similarly, of the five samples from patients who progressed from plateau phase, hypermethylation of p15, p16, E-CAD, DAPK, and ER occurred in five (80%), two (40%), five (100%), five (100%), and three (60%). None of the cases had hypermethylation of RIZ1, p73, VHL, RARbeta, and MGMT. At diagnosis, all patients had concurrent hypermethylation of at least three genes, and five (62%) had concurrent methylation of four or more genes. One patient with plasmacytoma had methylation of E-CAD, ER, and DAPK.

CONCLUSION

p15, p16, ER, DAPK, and E-CAD (but not RARbeta, p73, VHL, RIZ1, and MGMT) were frequently methylated in MM at both diagnosis and disease progression. Future studies of larger scale are needed to identify the genes responsible for disease progression.

The RING domain of PIASy is involved in the suppression of bone morphogenetic protein-signaling pathway

Bone morphogenetic proteins (BMPs) play central roles in differentiation, development, and physiologic tissue remodeling. Recently, we have demonstrated that a protein inhibitor of activated STAT, PIASy, suppresses TGF-beta signaling by interacting with Sma and MAD-related protein 3 (Smad3). In this study, we examined a PIASy-dependent inhibitory effect on BMP signaling. PIASy expression was induced by BMP-2 stimulation and suppressed BMP-2-dependent Smad activity in hepatoma cells. Furthermore, BMP-2-regulated Smads directly bound to PIASy. We also demonstrated that the RING domain of PIASy played an important role in PIASy-mediated suppression of Smad activity. We here provide evidence that the inhibitory action of PIASy on BMP-regulated Smad activity was due to direct physical interactions between Smads and PIASy through its RING domain.

Transcriptional inactivation of STAT3 by PPARgamma suppresses IL-6-responsive multiple myeloma cells

Multiple myeloma (MM) remains largely incurable despite conventional and high-dose therapies. Therefore, novel biologically based treatment approaches are urgently required. Here we demonstrate that expression of peroxisome proliferator-activated receptor gamma (PPARgamma) in MM cells and its agonists 15-d-PGJ2 and troglitazone completely abolished IL-6-inducible MM cell proliferation and induced apoptosis through affecting expression of multiple cell cycle or apoptosis genes, whereas PPARgamma antagonist GW9662 and PPARalpha agonist WY14643 did not display this inhibitory effect. These PPARgamma agonists significantly inhibited DNA binding and transactivation of STAT3 bound to the promoter of target genes in chromatin, but did not affect the expression of IL-6 receptor and phosphorylation of JAK/STAT3, MAPK, and PI3K/Akt. Interestingly, although inactivation of STAT3 by PPARgamma agonists is in a PPARgamma-dependent manner, the molecular mechanism by which two structurally distinct PPARgamma agonists suppress IL-6-activated STAT3 shows the divergent interactions between PPARgamma and STAT3 including direct or SMRT-mediated association.