Depletion of tristetraprolin in breast cancer cells increases interleukin-16 expression and promotes tumor infiltration with monocytes/macrophages

Bacterial endotoxin lipopolysaccharides regulate gene expression in human colon cancer cells

OBJECTIVE

Lipopolysaccharide (LPS) is a major cell wall component of gram-negative bacteria. Colon bacteria contribute to LPS which promotes colon cancer metastasis. The objective of this study was to survey the effect of LPS on cell viability and gene expression of 55 molecular targets in human colon cancer cells.

RESULTS

LPS did not affect the viability of COLO 225 cells under the culture conditions but affected the expression of a number of genes important in inflammatory responses and cancer development. LPS increased TTP family, GLUT family and DGAT1 mRNA levels but decreased DGAT2a and DGAT2b expression in the human colon cancer cells. LPS also increased COX2, CXCL1, ELK1, ICAM1, TNFSF10 and ZFAND5 but decreased BCL2L1, CYP19A1 and E2F1 mRNA levels in the colon cancer cells. These data suggest that LPS has profound effects on gene expression in human colon cancer cells.

The HDAC2-SP1 Axis Orchestrates Protumor Macrophage Polarization

Tumor-associated macrophages (TAM), including antitumor M1-like TAMs and protumor M2-like TAMs, are transcriptionally dynamic innate immune cells with diverse roles in lung cancer development. Epigenetic regulators are key in controlling macrophage fate in the heterogeneous tumor microenvironment. Here, we demonstrate that the spatial proximity of HDAC2-overexpressing M2-like TAMs to tumor cells significantly correlates with poor overall survival of lung cancer patients. Suppression of HDAC2 in TAMs altered macrophage phenotype, migration, and signaling pathways related to interleukins, chemokines, cytokines, and T-cell activation. In coculture systems of TAMs and cancer cells, suppressing HDAC2 in TAMs resulted in reduced proliferation and migration, increased apoptosis of cancer cell lines and primary lung cancer cells, and attenuated endothelial cell tube formation. HDAC2 regulated the M2-like TAM phenotype via acetylation of histone H3 and transcription factor SP1. Myeloid cell-specific deletion of Hdac2 and pharmacologic inhibition of class I HDACs in four different murine lung cancer models induced the switch from M2-like to M1-like TAMs, altered infiltration of CD4+ and CD8+ T cells, and reduced tumor growth and angiogenesis. TAM-specific HDAC2 expression may provide a biomarker for lung cancer stratification and a target for developing improved therapeutic approaches.

SIGNIFICANCE

HDAC2 inhibition reverses the protumor phenotype of macrophages mediated by epigenetic modulation induced by the HDAC2-SP1 axis, indicating a therapeutic option to modify the immunosuppressive tumor microenvironment.

RNA binding proteins (RBPs) and their role in DNA damage and radiation response in cancer

Traditionally majority of eukaryotic gene expression is influenced by transcriptional and post-transcriptional events. Alterations in the expression of proteins that act post-transcriptionally can affect cellular signaling and homeostasis. RNA binding proteins (RBPs) are a family of proteins that specifically bind to RNAs and are involved in post-transcriptional regulation of gene expression and important cellular processes such as cell differentiation and metabolism. Deregulation of RNA-RBP interactions and any changes in RBP expression or function can lead to various diseases including cancer. In cancer cells, RBPs play an important role in regulating the expression of tumor suppressors and oncoproteins involved in various cell-signaling pathways. Several RBPs such as HuR, AUF1, RBM38, LIN28, RBM24, tristetrapolin family and Musashi play critical roles in various types of cancers and their aberrant expression in cancer cells makes them an attractive therapeutic target for cancer treatment. In this review we provide an overview of i). RBPs involved in cancer progression and their mechanism of action ii). the role of RBPs, including HuR, in breast cancer progression and DNA damage response and iii). explore RBPs with emphasis on HuR as therapeutic target for breast cancer therapy.

Identification of Bcl2 as a Stably Expressed qPCR Reference Gene for Human Colon Cancer Cells Treated with Cottonseed-Derived Gossypol and Bioactive Extracts and Bacteria-Derived Lipopolysaccharides

Cottonseed contains many bioactive molecules including plant polyphenols. Cottonseed value might be increased by providing high-value bioactive polyphenols for improving nutrition and health. However, there was a lack of molecular evidence for cottonseed bioactivity in mammalian cells. One widely used method for evaluating the bioactivity of natural products is quantitative real-time-PCR (qPCR). The selection of stably expressed internal reference genes is a crucial task of qPCR assay for data analysis. The rationale for reference gene selection is that a lower standard deviation of the cycle of threshold (Cq) among the treatments indicates a more stable expression of the gene. The objective of this study was to select reference genes in human colon cancer cells (COLO 205) treated with cottonseed-derived gossypol and bioactive extracts along with bacterial endotoxin lipopolysaccharides (LPS). SYBR Green qPCR was used to analyze the mRNA levels of a wide range of biomarkers involved in glucose transport, lipid biosynthesis, inflammatory response, and cancer development. qPCR data (10,560 Cq values) were generated from 55 genes analyzed from 64 treatments with triplicate per treatment for each gene. The data showed that B-cell lymphoma 2 (Bcl2) mRNA was the most stable among the 55 mRNAs analyzed in the human colon cancer cells. Glyceraldehyde 3 phosphate dehydrogenase (Gapdh) and ribosome protein L32 (Rpl32) mRNAs were not good qPCR references for the colon cancer cells. These observations were consistent regardless of the treatment comparison between gossypol and LPS, glanded and glandless seed extracts, seed coat and kernel extracts, or treatment for 8 and 24 h. These results suggest that Bcl2 is a preferable reference gene for qPCR assays in human colon cancer cells treated with cottonseed-derived gossypol and bioactive extracts as well as LPS. The extensive qPCR results firmly support the conclusion that the Bcl2 gene is stably expressed at the mRNA level in the human colon cancer cells regardless of the treatment, suggesting that Bcl2 gene expression is not regulated at the mRNA level but at the post-transcriptional level. These results should facilitate studies designated to evaluate bioactivity on gene expression regulation by cottonseed molecules and other natural and synthetic molecules for nutrition and health uses.

Rat Mammary carcinoma susceptibility 3 (Mcs3) pleiotropy, socioenvironmental interaction, and comparative genomics with orthologous human 15q25.1-25.2

Genome-wide association studies of breast cancer susceptibility have revealed risk-associated genetic variants and nominated candidate genes; however, the identification of causal variants and genes is often undetermined by genome-wide association studies. Comparative genomics, utilizing Rattus norvegicus strains differing in susceptibility to mammary tumor development, is a complimentary approach to identify breast cancer susceptibility genes. Mammary carcinoma susceptibility 3 (Mcs3) is a Copenhagen (COP/NHsd) allele that confers resistance to mammary carcinomas when introgressed into a mammary carcinoma susceptible Wistar Furth (WF/NHsd) genome. Here, Mcs3 was positionally mapped to a 7.2-Mb region of RNO1 spanning rs8149408 to rs107402736 (chr1:143700228-150929594, build 6.0/rn6) using WF.COP congenic strains and 7,12-dimethylbenz(a)anthracene-induced mammary carcinogenesis. Male and female WF.COP-Mcs3 rats had significantly lower body mass compared to the Wistar Furth strain. The effect on female body mass was observed only when females were raised in the absence of males indicating a socioenvironmental interaction. Furthermore, female WF.COP-Mcs3 rats, raised in the absence of males, did not develop enhanced lobuloalveolar morphologies compared to those observed in the Wistar Furth strain. Human 15q25.1-25.2 was determined to be orthologous to rat Mcs3 (chr15:80005820-82285404 and chr15:83134545-84130720, build GRCh38/hg38). A public database search of 15q25.1-25.2 revealed genome-wide significant and nominally significant associations for body mass traits and breast cancer risk. These results support the existence of a breast cancer risk-associated allele at human 15q25.1-25.2 and warrant ultrafine mapping of rat Mcs3 and human 15q25.1-25.2 to discover novel causal genes and variants.

ZFP36 Inhibits Tumor Progression of Human Prostate Cancer by Targeting CDK6 and Oxidative Stress

Background

The expression of ZFP36 in previous study was reduced in prostate cancer (PCa) tissues as compared to benign prostate tissues, indicating the potential of ZFP36 as an auxiliary marker for PCa. Further evaluation was conducted in clinical samples for in vitro and in vivo experiments, to prove the potential possibility that ZFP36 dysregulation participated in the malignant phenotype of PCa, to determine its potential mechanism for tumor regulation, and to provide a new theoretical basis for gene therapy of PCa.

Methods

First, the expression of ZFP36 in prostate tissue and PCa tissue was explored, and the relationship between ZFP36 and clinical features of PCa patients was illustrated. Subsequently, the impact of ZFP36 on the biology of PCa cells and relevant downstream pathways of ZFP36's biological impact on PCa were elucidated. Finally, whether oxidative stress mediated the regulation of ZFP36 in PCa was verified by the determination of oxidative stress-related indicators and bioinformatics analysis.

Results

The downregulation of ZFP36 in PCa tissue had a positive correlation with high Gleason scores, advanced pathological stage, and biochemical recurrence. ZFP36 was identified as an independent prognostic factor for PCa patients' BCR-free survival (P = 0.022) by survival analysis. Following a subsequent experiment of function gain and loss, ZFP36 inhibited the proliferation, invasion, and migration in DU145 and 22RV1 cells and inhibits tumor growth in the mouse model. Additionally, high-throughput sequencing screened out CDK6 as the downstream target gene of ZFP36. Western blot/Q-PCR demonstrated that overexpression of ZFP36 could reduce the expression of CDK6 at both cellular and animal levels, and the dual-luciferase experiment and RIP experiment proved that CDK6 was the downstream target of ZFP36, indicating that CDK6 was a downstream target of ZFP36, which mediated tumor cell growth by blocking cell cycle at the G1 stage. Furthermore, ZFP36 inhibited oxidative stress in PCa cells.

Conclusions

In PCa, ZFP36 might be a tumor suppressor that regulated growth, invasion, and migration of PCa cells. The lately discovered ZFP36-CDK6 axis demonstrated the molecular mechanism of PCa progression to a certain extent which might act as a new possible therapeutic target of PCa therapy.

Cottonseed extracts regulate gene expression in human colon cancer cells

Cotton plant provides economically important fiber and cottonseed, but cottonseed contributes 20% of the crop value. Cottonseed value could be increased by providing high value bioactive compounds and polyphenolic extracts aimed at improving nutrition and preventing diseases because plant polyphenol extracts have been used as medicinal remedy for various diseases. The objective of this study was to investigate the effects of cottonseed extracts on cell viability and gene expression in human colon cancer cells. COLO 225 cells were treated with ethanol extracts from glanded and glandless cottonseed followed by MTT and qPCR assays. Cottonseed extracts showed minor effects on cell viability. qPCR assay analyzed 55 mRNAs involved in several pathways including DGAT, GLUT, TTP, IL, gossypol-regulated and TTP-mediated pathways. Using BCL2 mRNA as the internal reference, qPCR analysis showed minor effects of ethanol extracts from glanded seed coat and kernel and glandless seed coat on mRNA levels in the cells. However, glandless seed kernel extract significantly reduced mRNA levels of many genes involved in glucose transport, lipid biosynthesis and inflammation. The inhibitory effects of glandless kernel extract on gene expression may provide a useful opportunity for improving nutrition and healthcare associated with colon cancer. This in turn may provide the potential of increasing cottonseed value by using ethanol extract as a nutrition/health intervention agent.

CD163+ cytokine-producing cDC2 stimulate intratumoral type 1 T cell responses in HPV16-induced oropharyngeal cancer

Background

Human papillomavirus (HPV)-associated oropharyngeal squamous cell carcinoma (OPSCC) is a distinct clinical entity with a much better prognosis after (chemo)radiotherapy than HPV-negative OPSCC, especially in patients with a concomitant intratumoral HPV-specific and type-1 cytokine-oriented T cell response. However, knowledge on the type of myeloid cells and their coordination with intratumoral T cells and influence on patient outcome in OPSCC is lacking.

Methods

We analyzed the presence of intratumoral myeloid cells and their relationship to tumor-infiltrating T cells and patient outcome in a well-described cohort of HPV16⁺ patients with OPSCC using multispectral immunofluorescence, flow cytometry and functional analyses.

Results

We show that the tumor microenvironment of HPV16⁺ OPSCC tumors with such an ongoing HPV16-specific T cell response is highly infiltrated with a newly defined CD163⁺ cytokine-producing subset of conventional dendritic cell type 2 (cDC2), called DC3. These CD163⁺ cDC2 predominantly stimulated type 1 T cell polarization and produced high levels of interleukin-12 (IL-12) and IL-18, required for IFNγ and IL-22 production by T cells after cognate antigen stimulation. Tumor-infiltration with these CD163⁺ cDC2 positively correlated with the infiltration by Tbet⁺ and tumor-specific T cells, and with prolonged survival.

Conclusions

These data suggest an important role for intratumoral CD163⁺ cDC2 in stimulating tumor-infiltrating T cells to exert their antitumor effects.

Tristetraprolin: A cytosolic regulator of mRNA turnover moonlighting as transcriptional corepressor of gene expression

Tristetraprolin (TTP) is a nucleocytoplasmic 326 amino acid protein whose sequence is characterized by possessing two CCCH-type zinc finger domains. In the cytoplasm TTP function is to promote the degradation of mRNAs that contain adenylate/uridylate-rich elements (AREs). Mechanistically, TTP promotes the recruitment of poly(A)-specific deadenylases and exoribonucleases. By reducing the half-life of about 10% of all the transcripts in the cell TTP has been shown to participate in multiple cell processes that include regulation of gene expression, cell proliferation, metabolic homeostasis and control of inflammation and immune responses. However, beyond its role in mRNA decay, in the cell nucleus TTP acts as a transcriptional coregulator by interacting with chromatin modifying enzymes. TTP has been shown to repress the transactivation of NF-κB and estrogen receptor suggesting the possibility that it participates in the transcriptional regulation of hundreds of genes in human cells and its possible involvement in breast cancer progression. In this review, we discuss the cytoplasmic and nuclear functions of TTP and the effect of the dysregulation of its protein levels in the development of human diseases. We suggest that TTP be classified as a moonlighting tumor supressor protein that regulates gene expression through two different mechanims; the decay of ARE-mRNAs and a transcriptional coregulatory function.

Gossypol decreased cell viability and down-regulated the expression of a number of genes in human colon cancer cells

Plant polyphenol gossypol has anticancer activities. This may increase cottonseed value by using gossypol as a health intervention agent. It is necessary to understand its molecular mechanisms before human consumption. The aim was to uncover the effects of gossypol on cell viability and gene expression in cancer cells. In this study, human colon cancer cells (COLO 225) were treated with gossypol. MTT assay showed significant inhibitory effect under high concentration and longtime treatment. We analyzed the expression of 55 genes at the mRNA level in the cells; many of them are regulated by gossypol or ZFP36/TTP in cancer cells. BCL2 mRNA was the most stable among the 55 mRNAs analyzed in human colon cancer cells. GAPDH and RPL32 mRNAs were not good qPCR references for the colon cancer cells. Gossypol decreased the mRNA levels of DGAT, GLUT, TTP, IL families and a number of previously reported genes. In particular, gossypol suppressed the expression of genes coding for CLAUDIN1, ELK1, FAS, GAPDH, IL2, IL8 and ZFAND5 mRNAs, but enhanced the expression of the gene coding for GLUT3 mRNA. The results showed that gossypol inhibited cell survival with decreased expression of a number of genes in the colon cancer cells.

The oncogenic and tumor suppressive roles of RNA-binding proteins in human cancers

Posttranscriptional regulation is a mechanism for the cells to control gene regulation at the RNA level. In this process, RNA-binding proteins (RBPs) play central roles and orchestrate the function of RNA molecules in multiple steps. Accumulating evidence has shown that the aberrant regulation of RBPs makes  contributions to the initiation and progression of tumorigenesis via numerous mechanisms such as genetic changes, epigenetic alterations, and noncoding RNA-mediated regulations. In this article, we review the effects caused by RBPs and their functional diversity in the malignant transformation of cancer cells that occurs through the involvement of these proteins in various stages of RNA regulation including alternative splicing, stability, polyadenylation, localization, and translation. Besides this, we review the various interactions between RBPs and other crucial posttranscriptional regulators such as microRNAs and long noncoding RNAs in the pathogenesis of cancer. Finally, we discuss the potential approaches for targeting RBPs in human cancers.

Differential effectiveness of tyrosine kinase inhibitors in 2D/3D culture according to cell differentiation, p53 status and mitochondrial respiration in liver cancer cells

Sorafenib and Regorafenib are the recommended first- and second-line therapies in patients with advanced hepatocellular carcinoma (HCC). Lenvatinib and Cabozantinib have shown non-inferior antitumoral activities compared with the corresponding recommended therapies. The clinical trials have established recommended doses for each treatment that lead different blood concentrations in patients for Sorafenib (10 µM), Regorafenib (1 µM), Lenvatinib (0.1 µM), and Cabozantinib (1 µM). However, very low response rates are observed in patients attributed to intrinsic resistances or upregulation of survival signaling. The aim of the study was the comparative dose-response analysis of the drugs (0-100 µM) in well-differentiated (HepG2, Hep3B, and Huh7), moderately (SNU423), and poorly (SNU449) differentiated liver cancer cells in 2D/3D cultures. Cells harbors wild-type p53 (HepG2), non-sense p53 mutation (Hep3B), inframe p53 gene deletion (SNU423), and p53 point mutation (Huh7 and SNU449). The administration of regular used in vitro dose (10 µM) in 3D and 2D cultures, as well as the dose-response analysis in 2D cultures showed Sorafenib and Regorafenib were increasingly effective in reducing cell proliferation, and inducing apoptosis in well-differentiated and expressing wild-type p53 in HCC cells. Lenvatinib and Cabozantinib were particularly effective in moderately to poorly differentiated cells with mutated or lacking p53 that have lower basal oxygen consumption rate (OCR), ATP, and maximal respiration capacity than observed in differentiated HCC cells. Sorafenib and Regorafenib downregulated, and Lenvatinib and Cabozantinib upregulated epidermal growth factor receptor (EGFR) and mesenchymal-epithelial transition factor receptor (c-Met) in HepG2 cells. Conclusions: Sorafenib and Regorafenib were especially active in well-differentiated cells, with wild-type p53 and increased mitochondrial respiration. By contrast, Lenvatinib and Cabozantinib appeared more effective in moderately to poorly differentiated cells with mutated p53 and low mitochondrial respiration. The development of strategies that allow us to deliver increased doses in tumors might potentially enhance the effectiveness of the treatments.

The mRNA-binding Protein TTP/ZFP36 in Hepatocarcinogenesis and Hepatocellular Carcinoma

Hepatic lipid deposition and inflammation represent risk factors for hepatocellular carcinoma (HCC). The mRNA-binding protein tristetraprolin (TTP, gene name ZFP36) has been suggested as a tumor suppressor in several malignancies, but it increases insulin resistance. The aim of this study was to elucidate the role of TTP in hepatocarcinogenesis and HCC progression. Employing liver-specific TTP-knockout (lsTtp-KO) mice in the diethylnitrosamine (DEN) hepatocarcinogenesis model, we observed a significantly reduced tumor burden compared to wild-type animals. Upon short-term DEN treatment, modelling early inflammatory processes in hepatocarcinogenesis, lsTtp-KO mice exhibited a reduced monocyte/macrophage ratio as compared to wild-type mice. While short-term DEN strongly induced an abundance of saturated and poly-unsaturated hepatic fatty acids, lsTtp-KO mice did not show these changes. These findings suggested anti-carcinogenic actions of TTP deletion due to effects on inflammation and metabolism. Interestingly, though, investigating effects of TTP on different hallmarks of cancer suggested tumor-suppressing actions: TTP inhibited proliferation, attenuated migration, and slightly increased chemosensitivity. In line with a tumor-suppressing activity, we observed a reduced expression of several oncogenes in TTP-overexpressing cells. Accordingly, ZFP36 expression was downregulated in tumor tissues in three large human data sets. Taken together, this study suggests that hepatocytic TTP promotes hepatocarcinogenesis, while it shows tumor-suppressive actions during hepatic tumor progression.

Cancer the'RBP'eutics-RNA-binding proteins as therapeutic targets for cancer

RNA-binding proteins (RBPs) play a critical role in the regulation of various RNA processes, including splicing, cleavage and polyadenylation, transport, translation and degradation of coding RNAs, non-coding RNAs and microRNAs. Recent studies indicate that RBPs not only play an instrumental role in normal cellular processes but have also emerged as major players in the development and spread of cancer. Herein, we review the current knowledge about RNA binding proteins and their role in tumorigenesis as well as the potential to target RBPs for cancer therapeutics.

Thymoquinone-Induced Tristetraprolin Inhibits Tumor Growth and Metastasis through Destabilization of MUC4 mRNA

Tristetraprolin (TTP), a well-characterized AU-rich element (ARE) binding protein, functions as a tumor suppressor gene. The purpose of this study was to investigate whether a bioactive substance derived from a natural medicinal plant affects the induction of TTP and to elucidate its mechanism. We examined the effects of natural bioactive materials including Resveratrol (RSV), thymoquinone (TQ) and curcumin on the expression of TTP in cancer cell. TQ derived from a natural plant Nigella sativa increased the expression levels of TTP mRNA and proteins in a dose-dependent manner in gastric and breast cancer cells. TQ-induced TTP increased the instability of MUC4 mRNA by direct binding of TTP to ARE in the 3′UTR of MUC4 mRNA. The induction of TTP by TQ also reduced the proliferation, migration and invasion of cancer cells. The expression of the epithelial-mesenchymal (EMT)-related genes, which were target genes of TTP, was also decreased by the TQ treatment. In the in vivo experiments using mouse melanoma cells, TQ-induced TTP inhibited metastasis of tumor cells. We have found that TQ-induced TTP might inhibit metastasis by reducing tumor cell migration and invasion through destabilization of MUC4 mRNA, which suggest the MUC4 as a novel target to TTP.

Macrophages attenuate the transcription of CYP1A1 in breast tumor cells and enhance their proliferation

While aberrant cells are routinely recognized and removed by immune cells, tumors eventually escape innate immune responses. Infiltrating immune cells are even corrupted by the tumor to acquire a tumor-supporting phenotype. In line, tumor-associated macrophages are well-characterized to promote tumor progression and high levels of tumor-infiltrating macrophages are a poor prognostic marker in breast cancer. Here, we aimed to further decipher the influence of macrophages on breast tumor cells and determined global gene expression changes in three-dimensional tumor spheroids upon infiltration of macrophages. While various tumor-associated mRNAs were upregulated, expression of the cytochrome P450 family member CYP1A1 was markedly attenuated. Repression of CYP1A1 in tumor cells was elicited by a macrophage-shaped tumor microenvironment rather than by direct tumor cell-macrophage contacts. In line with changes in RNA expression profiles, macrophages enhanced proliferation of the tumor cells. Enhanced proliferation and macrophage presence further correlated with reduced CYP1A1 expression in patient tumors when compared with normal tissue. These findings are of interest in the context of combinatory therapeutic approaches involving cytotoxic and immune-modulatory compounds.

Immunomodulatory role of histamine H4 receptor in breast cancer

BACKGROUND

Although the role of histamine H4 receptor (H4R) in immune cells is being extensively investigated, its immunomodulatory function in cancer is completely unknown. This study aimed to investigate the role of H4R in antitumour immunity in a model of triple-negative breast cancer.

METHODS

We evaluated growth parameters, histological characteristics and the composition of tumour, splenic and tumour draining lymph node (TDLN) immune subsets, in a syngeneic model, developed orthotopically with 4T1 cells in H4R knockout (H4R-KO) and wild-type mice.

RESULTS

Mice lacking H4R show reduced tumour size and weight, decreased number of lung metastases and percentage of CD4+ tumour-infiltrating T cells, while exhibiting increased infiltration of NK cells and CD19+ lymphocytes. Likewise, TDLN of H4R-KO mice show decreased CD4+ T cells and T regulatory cells (CD4+CD25+FoxP3+), and increased percentages of NK cells. Finally, H4R-deficient mice show decreased Tregs in spleens and non-draining lymph nodes, and a negative correlation between tumour weight and the percentages of CD4+, CD19+ and NK splenic cells, suggesting that H4R also regulates antitumour immunity at a systemic level.

CONCLUSIONS

This is the first report that demonstrates the participation of H4R in antitumour immunity, suggesting that H4R could be a target for cancer treatment.

Roles of Tristetraprolin in Tumorigenesis

Genetic loss or mutations in tumor suppressor genes promote tumorigenesis. The prospective tumor suppressor tristetraprolin (TTP) has been shown to negatively regulate tumorigenesis through destabilizing the messenger RNAs of critical genes implicated in both tumor onset and tumor progression. Regulation of TTP has therefore emerged as an important issue in tumorigenesis. Similar to other tumor suppressors, TTP expression is frequently downregualted in various human cancers, and its low expression is correlated with poor prognosis. Additionally, disruption in the regulation of TTP by various mechanisms results in the inactivation of TTP protein or altered TTP expression. A recent study showing alleviation of Myc-driven lymphomagenesis by the forced expression of TTP has shed light on new therapeutic avenues for cancer prevention and treatment through the restoration of TTP expression. In this review, we summarize key oncogenes subjected to the TTP-mediated mRNA degradation, and discuss how dysregulation of TTP can contribute to tumorigenesis. In addition, the control mechanism underlying TTP expression at the posttranscriptional and posttranslational levels will be discussed.

Tristetraprolin Is a Prognostic Biomarker for Poor Outcomes among Patients with Low-Grade Prostate Cancer

Background: We studied the utility of the tumor suppressor Tristetraprolin (TTP, ZFP36) as a clinically relevant biomarker of aggressive disease in prostate cancer patients after radical prostatectomy (RP).Methods: TTP RNA expression was measured in an RP cohort of patients treated at Moffitt Cancer Center (MCC) and obtained from six publically available RP datasets with biochemical recurrence (BCR; total n = 1,394) and/or metastatic outcome data (total n = 1,222). TTP protein expression was measured by immunohistochemistry in a tissue microarray of 153 MCC RP samples. The time to BCR or metastasis based on TTP RNA or protein levels was calculated using the Kaplan-Meier analysis. Univariable and multivariable Cox proportional hazard models were performed on multiple cohorts to evaluate if TTP is a clinically relevant biomarker and to assess if TTP improves upon the Cancer of the Prostate Risk Assessment postsurgical (CAPRA-S) score for predicting clinical outcomes.Results: In all of the RP patient cohorts, prostate cancer with low TTP RNA or protein levels had decreased time to BCR or metastasis versus TTP-high tumors. Further, the decreased time to BCR in TTP-low prostate cancer was more pronounced in low-grade tumors. Finally, pooled survival analysis suggests that TTP RNA expression provides independent information beyond CAPRA-S to predict BCR.Conclusions: TTP is a promising prostate cancer biomarker for predicting which RP patients will have poor outcomes, especially for low-grade prostate cancer patients.Impact: This study suggests that TTP RNA expression can be used to enhance the accuracy of CAPRA-S to predict outcomes in patients treated with RP. Cancer Epidemiol Biomarkers Prev; 27(11); 1376-83. ©2018 AACR.

Tristetraprolin Overexpression in Gastric Cancer Cells Suppresses PD-L1 Expression and Inhibits Tumor Progression by Enhancing Antitumor Immunity

The RNA-binding protein tristetraprolin (TTP) binds to adenosine-uridine AU-rich elements in the 3'-untranslated region of messenger RNAs and facilitates rapid degradation of the target mRNAs. Therefore, it regulates the expression of multiple cancer and immunity-associated transcripts. Furthermore, a lack of TTP in cancer cells influences cancer progression and predicts poor survival. Although the functions of TTP on cancer cells have previously been researched, the mechanism of TTP on the interaction between cancer cells with their microenvironment remains undiscovered. In this study, we admed to determine the role of cancer cell TTP during the interaction between tumor and immune cells, specifically regulatory T cells (Tregs). We evaluate the capability of TTP to modulate the antitumor immunity of GC and explored the underlying mechanism. The overexpression of TTP in GC cells dramatically increased peripheral blood mononuclear lymphocyte (PBML) -mediated cytotoxicity against GC cells. Increased cytotoxicity against TTP-overexpressed GC cells by PBMLs was determined by Treg development and infiltration. Surprisingly, we found the stabilization of programmed death-ligand 1 (PD-L1) mRNA was declining while TTP was elevated. The PD-L1 protein level was reduced in TTP-abundant GC cells. PD-L1 gas been found to play a pivotal role in Treg development and functional maintenance in immune system. Taken together, our results suggest the overexpression of TTP in GC cells not only affects cell survival and apoptosis but also increases PBMLs -mediated cytotoxicity against GC cells to decelerate tumor progression. Moreover, we identified PD-L1 as a critical TTP-regulated factor that contributes to inhibiting antitumor immunity.

PIM2 interacts with tristetraprolin and promotes breast cancer tumorigenesis

Tristetraprolin (TTP) is an AU‐rich element‐binding protein that regulates mRNA stability and plays important roles in cancer. The mechanisms by which TTP is regulated in breast cancer are poorly understood. Using multiple biochemical approaches, we found that proviral insertion in murine lymphomas 2 (PIM2) is a novel binding partner of TTP. Interestingly, PIM2 decreased TTP protein levels independent of its kinase activity. PIM2 instead targeted TTP protein for degradation via the ubiquitin‐proteasome pathway. Furthermore, immunohistochemical staining showed that PIM2 and TTP protein levels were negatively correlated in human breast cancer samples. Indeed, PIM2 overexpression de‐repressed TTP‐mediated inhibition of breast cancer cell proliferation and migration in vitro and promoted breast tumor xenograft growth in vivo. These findings demonstrate an important role for the PIM2‐TTP complex in breast cancer tumorigenesis, suggesting that PIM2 may represent a potential therapeutic target for breast cancer treatment.

Tristetraprolin disables prostate cancer maintenance by impairing proliferation and metabolic function

Tristetraprolin (TTP) is an RNA-binding protein that post-transcriptionally suppresses gene expression by delivering mRNA cargo to processing bodies (P-bodies) where the mRNA is degraded. TTP functions as a tumor suppressor in a mouse model of B cell lymphoma, and in some human malignancies low TTP expression correlates with reduced survival. Here we report important prognostic and functional roles for TTP in human prostate cancer. First, gene expression analysis of prostate tumors revealed low TTP expression correlates with patients having high-risk Gleason scores and increased biochemical recurrence. Second, in prostate cancer cells with low levels of endogenous TTP, inducible TTP expression inhibits their growth and proliferation, as well as their clonogenic growth. Third, TTP functions as a tumor suppressor in prostate cancer, as forced TTP expression markedly impairs the tumorigenic potential of prostate cancer cells in a mouse xenograft model. Finally, pathway analysis of gene expression data suggested metabolism is altered by TTP expression in prostate tumor cells, and metabolic analyses revealed that such processes are impaired by TTP, including mitochondrial respiration. Collectively, these findings suggest that TTP is an important prognostic indicator for prostate cancer, and augmenting TTP function would effectively disable the metabolism and proliferation of aggressive prostate tumors.

Neutrophil-Derived Interleukin 16 in Premetastatic Lungs Promotes Breast Tumor Cell Seeding

The premetastatic niche in distant organs prior to metastatic cell arrival emerged as an important step in the metastatic cascade. However, molecular mechanisms underlying this process are still poorly understood. In particular, whether neutrophil recruitment at a premetastatic stage promotes or inhibits metastatic cell seeding has to be clarified. We aimed at unraveling how neutrophil infiltration in lung parenchyma induced by the distant primary tumor influences the establishment of lung metastasis. Elevated neutrophil counts and IL-16 levels were found in premetastatic lungs in a syngenic mouse model using 4T1 tumor cells. 4T1 cell-derived soluble factors stimulated IL-16 secretion by neutrophils. The functional contribution of IL-16 is supported by metastasis burden reduction in lungs observed on instillation of an IL-16 neutralizing antibody. Moreover, IL-16 promotes in vitro 4T1 cell adhesiveness, invasiveness, and migration. In conclusion, at a premetastatic stage, neutrophil-derived IL-16 favors tumor cell engraftment in lung parenchyma.

The RNA-binding protein HuR inhibits expression of CCL5 and limits recruitment of macrophages into tumors

The RNA-binding protein HuR promotes tumor growth by affecting proliferation, metastasis, apoptosis, and angiogenesis. Although immune cells, especially tumor-associated macrophages, are critical components of the tumor stroma, the influence of HuR in tumors on the recruitment of immune cells remains poorly understood. In the present study, we, therefore, aimed to elucidate the impact of tumor cell HuR on the interaction between tumor cells and macrophages. To this end, we stably depleted HuR in human MCF-7 breast cancer cells. We found that HuR-deficient cells not only showed reduced proliferation, they further expressed elevated levels of the chemokine CCL5. HuR-dependent repression of CCL5 was neither caused by altered CCL5 mRNA stability, nor by changes in CCL5 translation. Instead, loss of HuR augmented transcription of CCL5, which was mediated via an interferon-stimulated response element in the CCL5 promoter. Furthermore, HuR depletion enhanced macrophage recruitment into MCF-7 tumor spheroids, an effect which was completely lost upon neutralization of CCL5. HuR expression further negatively correlated with CCL5 expression and macrophage appearance in a cohort of breast tumors. Thus, while HuR is well-characterized to support various pro-tumorigenic features in tumor cells, we provide evidence that it limits the recruitment of macrophages into tumors by repressing CCL5. As macrophage infiltration is associated with poor prognosis, our findings underline the highly cell-type and context specific role of HuR in tumorigenesis.

Killing Is Not Enough: How Apoptosis Hijacks Tumor-Associated Macrophages to Promote Cancer Progression

Macrophages are a group of heterogeneous cells of the innate immune system that are crucial to the initiation, progression, and resolution of inflammation. Moreover, they control tissue homeostasis in healthy tissue and command a broad sensory arsenal to detect disturbances in tissue integrity. Macrophages possess a remarkable functional plasticity to respond to irregularities and to initiate programs that allow overcoming them in order to return back to normal. Thus, macrophages kill malignant or transformed cells, rearrange extracellular matrix, take up and recycle cellular as well as molecular debris, initiate cellular growth cascades, and favor directed migration of cells. As an example, apoptotic death of bystander cells is sensed by macrophages, initiating functional responses that support all hallmarks of cancer. In this chapter, we describe how tumor cell apoptosis hijacks tumor-associated macrophages to promote tumor growth. We propose that tumor therapy should not only kill malignant cells but also target the interaction of the host with apoptotic cancer cells, as this might be efficient to limit the protumor action of apoptotic cells and boost the antitumor potential of macrophages. Leaving the apoptotic cell/macrophage interaction untouched might also limit the benefit of conventional tumor cell apoptosis-focused therapy since surviving tumor cells might receive overwhelming support by the wound healing response that apoptotic tumor cells will trigger in local macrophages, thereby enhancing tumor recurrence.

The Fragment HMGA2-sh-3p20 from HMGA2 mRNA 3'UTR Promotes the Growth of Hepatoma Cells by Upregulating HMGA2

High mobility group A2 (HMGA2) plays a crucial role in the development of cancer. However, the mechanism by which HMGA2 promotes the growth of hepatocellular carcinoma (HCC) remains unclear. Here, we explore the hypothesis that HMGA2 may enhance the growth of hepatoma cells through a fragment based on the secondary structure of HMGA2 mRNA 3′-untranslated region (3′UTR). Bioinformatics analysis showed that HMGA2 mRNA displayed a hairpin structure within its 3′UTR, termed HMGA2-sh. Mechanistically, RNA immunoprecipitation assays showed that the microprocessor Drosha or DGCR8 interacted with HMGA2 mRNA in hepatoma cells. Then, Dicer contributes to the generation of the fragment HMGA2-sh-3p20 from the HMGA2-sh. HMGA2-sh-3p20 was screened by PCR analysis. Interestingly, HMGA2-sh-3p20 increased the expression of HMGA2 through antagonizing the tristetraprolin (TTP)-mediated degradation of HMGA2. HMGA2-sh-3p20 inhibited the expression of PTEN by targeting the 3′UTR of PTEN mRNA. In addition, the overexpression of PTEN could downregulate HMGA2 expression. Significantly, we documented the ability of HMGA2-sh-3p20 to promote the growth of hepatoma cells in vitro and in vivo. Thus, we conclude that the fragment HMGA2-sh-3p20 from HMGA2 mRNA 3′UTR promotes the growth of hepatoma cells by upregulating HMGA2. Our finding provides new insights into the mechanism by which HMGA2 enhances hepatocarcinogenesis.

Establishment and characterization of an orthotopic patient-derived Group 3 medulloblastoma model for preclinical drug evaluation

Medulloblastomas comprise a heterogeneous group of tumours and can be subdivided into four molecular subgroups (WNT, SHH, Group 3 and Group 4) with distinct prognosis, biological behaviour and implications for targeted therapies. Few experimental models exist of the aggressive and poorly characterized Group 3 tumours. In order to establish a reproducible transplantable Group 3 medulloblastoma model for preclinical therapeutic studies, we acquired a patient-derived tumour sphere culture and inoculated low-passage spheres into the cerebellums of NOD-scid mice. Mice developed symptoms of brain tumours with a latency of 17–18 weeks. Neurosphere cultures were re-established and serially transplanted for 3 generations, with a negative correlation between tumour latency and numbers of injected cells. Xenografts replicated the phenotype of the primary tumour, including high degree of clustering in DNA methylation analysis, high proliferation, expression of tumour markers, MYC amplification and elevated MYC expression, and sensitivity to the MYC inhibitor JQ1. Xenografts maintained maintained expression of tumour-derived VEGFA and stromal-derived COX-2. VEGFA, COX-2 and c-Myc are highly expressed in Group 3 compared to other medulloblastoma subgroups, suggesting that these molecules are relevant therapeutic targets in Group 3 medulloblastoma.

Post-transcriptional regulation of cytokine and growth factor signaling in cancer

Cytokines and growth factors regulate cell proliferation, differentiation, migration and apoptosis, and play important roles in coordinating growth signal responses during development. The expression of cytokine genes and the signals transmitted through cytokine receptors are tightly regulated at several levels, including transcriptional and post-transcriptional levels. A majority of cytokine mRNAs, including growth factor transcripts, contain AU-rich elements (AREs) in their 3' untranslated regions that control gene expression by regulating mRNA degradation and changing translational rates. In addition, numerous proteins involved in transmitting signals downstream of cytokine receptors are regulated at the level of mRNA degradation by GU-rich elements (GREs) found in their 3' untranslated regions. Abnormal stabilization and overexpression of ARE or GRE-containing transcripts had been observed in many malignancies, which is a consequence of the malfunction of RNA-binding proteins. In this review, we briefly summarize the role of AREs and GREs in regulating mRNA turnover to coordinate cytokine and growth factor expression, and we describe how dysregulation of mRNA degradation mechanisms contributes to the development and progression of cancer.

Metabolomics Analysis of Hormone-Responsive and Triple-Negative Breast Cancer Cell Responses to Paclitaxel Identify Key Metabolic Differences

To date, no targeted therapies are available to treat triple negative breast cancer (TNBC), while other breast cancer subtypes are responsive to current therapeutic treatment. Metabolomics was conducted to reveal differences in two hormone receptor-negative TNBC cell lines and two hormone receptor-positive Luminal A cell lines. Studies were conducted in the presence and absence of paclitaxel (Taxol). TNBC cell lines had higher levels of amino acids, branched-chain amino acids, nucleotides, and nucleotide sugars and lower levels of proliferation-related metabolites like choline compared with Luminal A cell lines. In the presence of paclitaxel, each cell line showed unique metabolic responses, with some similarities by type. For example, in the Luminal A cell lines, levels of lactate and creatine decreased while certain choline metabolites and myo-inositol increased with paclitaxel. In the TNBC cell lines levels of glutamine, glutamate, and glutathione increased, whereas lysine, proline, and valine decreased in the presence of drug. Profiling secreted inflammatory cytokines in the conditioned media demonstrated a greater response to paclitaxel in the hormone-positive Luminal cells compared with a secretion profile that suggested greater drug resistance in the TNBC cells. The most significant differences distinguishing the cell types based on pathway enrichment analyses were related to amino acid, lipid and carbohydrate metabolism pathways, whereas several biological pathways were differentiated between the cell lines following treatment.

Hallmarks of cancer and AU-rich elements

Post‐transcriptional control of gene expression is aberrant in cancer cells. Sustained stabilization and enhanced translation of specific mRNAs are features of tumor cells. AU‐rich elements (AREs), cis‐acting mRNA decay determinants, play a major role in the posttranscriptional regulation of many genes involved in cancer processes. This review discusses the role of aberrant ARE‐mediated posttranscriptional processes in each of the hallmarks of cancer, including sustained cellular growth, resistance to apoptosis, angiogenesis, invasion, and metastasis. WIREs RNA 2017, 8:e1368. doi: 10.1002/wrna.1368

For further resources related to this article, please visit the WIREs website.

Systematic Analysis of AU-Rich Element Expression in Cancer Reveals Common Functional Clusters Regulated by Key RNA-Binding Proteins

Defects in AU-rich elements (ARE)-mediated posttranscriptional control can lead to several abnormal processes that underlie carcinogenesis. Here, we performed a systematic analysis of ARE-mRNA expression across multiple cancer types. First, the ARE database (ARED) was intersected with The Cancer Genome Atlas databases and others. A large set of ARE-mRNAs was over-represented in cancer and, unlike non-ARE-mRNAs, correlated with the reversed balance in the expression of the RNA-binding proteins tristetraprolin (TTP, ZFP36) and HuR (ELAVL1). Serial statistical and functional enrichment clustering identified a cluster of 11 overexpressed ARE-mRNAs (CDC6, KIF11, PRC1, NEK2, NCAPG, CENPA, NUF2, KIF18A, CENPE, PBK, TOP2A) that negatively correlated with TTP/HuR mRNA ratios and was involved in the mitotic cell cycle. This cluster was upregulated in a number of solid cancers. Experimentally, we demonstrated that the ARE-mRNA cluster is upregulated in a number of tumor breast cell lines when compared with noninvasive and normal-like breast cancer cells. RNA-IP demonstrated the association of the ARE-mRNAs with TTP and HuR. Experimental modulation of TTP or HuR expression led to changes in the mitosis ARE-mRNAs. Posttranscriptional reporter assays confirmed the functionality of AREs. Moreover, TTP augmented mitotic cell-cycle arrest as demonstrated by flow cytometry and histone H3 phosphorylation. We found that poor breast cancer patient survival was significantly associated with low TTP/HuR mRNA ratios and correlated with high levels of the mitotic ARE-mRNA signature. These results significantly broaden the role of AREs and their binding proteins in cancer, and demonstrate that TTP induces an antimitotic pathway that is diminished in cancer. Cancer Res; 76(14); 4068-80. ©2016 AACR.

The next level of 3D tumour models: immunocompetence

The complexity of the tumour microenvironment encompasses interactions between cancer and stromal cells. Moving from 2D cell culture methods into 3D models enables more-accurate investigation of those interactions. Current 3D cancer models focus on cancer spheroid interaction with stromal cells, such as fibroblasts. However, over recent years, the cancer immune environment has been shown to have a major role in tumour progression. This review summarises the state-of-art on immunocompetent 3D cancer models that, in addition to cancer cells, also incorporate immune cells, including monocytes, cancer-associated macrophages, dendritic cells, neutrophils and lymphocytes.

Baseline blood immunological profiling differentiates between Her2-breast cancer molecular subtypes: implications for immunomediated mechanisms of treatment response

Purpose

Breast cancer patients’ response to treatment is highly dependent on the primary tumor molecular features, with triple-negative breast tumors having the worst prognosis of all subtypes. According to the molecular features, tumors stimulate the microenvironment to induce distinct immune responses, baseline immune activation being associated with higher likelihood of pathologic response. In this study, we investigated the deconvolution of the immunological status of triple-negative tumors in comparison with luminal tumors and the association with patients’ clinicopathological characteristics.

Patients and methods

Gene expression of 84 inflammatory molecules and their receptors were analyzed in 40 peripheral blood samples from patients with Her2− primary breast cancer tumors. We studied the association of triple-negative phenotype with age, clinical stage, tumor size, lymph nodes, and menopausal status.

Results

We observed that more patients with estrogen (ER)/progesterone (PR)-negative tumors had grade III, while more patients with ER/PR-positive tumors had grade II tumors. Gene expression analysis revealed a panel of 14 genes to have differential expression between the two groups: several interleukins: IL13, IL16, IL17C and IL17F, IL1A, IL3; interleukin receptors: IL10RB, IL5RA; chemokines: CXCL13 and CCL26; and cytokines: CSF2, IFNA2, OSM, TNSF13.

Conclusion

The expression levels of these genes have been previously shown to be associated with reduced immunological status; indeed, the triple-negative breast cancer patients presented with lower counts of lymphocytes and eosinophils than the ER/PR-positive ones. These results contribute to a better understanding of the possible role of antitumor immune responses in mediating the clinical outcome.

Control of pro-angiogenic cytokine mRNA half-life in cancer: the role of AU-rich elements and associated proteins

Control of mRNA half-life plays a central role in normal development and disease. Several pathological conditions, such as inflammation and cancer, tightly correlate with deregulation in mRNA stability of pro-inflammatory genes. Among these, pro-angiogenesis cytokines, which play a crucial role in the formation of new blood vessels, normally show rapid mRNA decay patterns. The mRNA half-life of these genes appears to be regulated by mRNA-binding proteins that interact with AU-rich elements (AREs) in the 3'-untranslated region of mRNAs. Some of these RNA-binding proteins, such as tristetraprolin (TTP), ARE RNA-binding protein 1, and KH-type splicing regulatory protein, normally promote mRNA degradation. Conversely, other proteins, such as embryonic lethal abnormal vision-like protein 1 (HuR) and polyadenylate-binding protein-interacting protein 2, act as antagonists, stabilizing the mRNA. The steady state levels of mRNA-binding proteins and their relative ratio is often perturbed in human cancers and associated with invasion and aggressiveness. Compelling evidence also suggests that underexpression of TTP and overexpression of HuR may be a useful prognostic and predictive marker in breast, colon, prostate, and brain cancers, indicating a potential therapeutic approach for these tumors. In this review, we summarize the main mechanisms involved in the regulation of mRNA decay of pro-angiogenesis cytokines in different cancers and discuss the interactions between the AU-rich-binding proteins and their mRNA targets.

Poly(ADP-ribose) polymerase-13 and RNA regulation in immunity and cancer

Post-transcriptional regulation of RNA is an important mechanism for activating and resolving cellular stress responses. Poly(ADP-ribose) polymerase-13 (PARP13), also known as ZC3HAV1 and zinc-finger antiviral protein (ZAP), is an RNA-binding protein that regulates the stability and translation of specific mRNAs, and modulates the miRNA silencing pathway to globally affect miRNA targets. These functions of PARP13 are important components of the cellular response to stress. In addition, the ability of PARP13 to restrict oncogenic viruses and to repress the prosurvival cytokine receptor tumor necrosis factor (TNF)-related apoptosis-inducing ligand receptor 4 (TRAILR4) suggests that it can be protective against malignant transformation and cancer development. The relevance of PARP13 to human health and disease make it a promising therapeutic target.

Regulation of the mRNA half-life in breast cancer

The control of the half-life of mRNA plays a central role in normal development and in disease progression. Several pathological conditions, such as breast cancer, correlate with deregulation of the half-life of mRNA encoding growth factors, oncogenes, cell cycle regulators and inflammatory cytokines that participate in cancer. Substantial stability means that a mRNA will be available for translation for a longer time, resulting in high levels of protein gene products, which may lead to prolonged responses that subsequently result in over-production of cellular mediators that participate in cancer. The stability of these mRNA is regulated at the 3’UTR level by different mechanisms involving mRNA binding proteins, micro-RNA, long non-coding RNA and alternative polyadenylation. All these events are tightly inter-connected to each other and lead to steady state levels of target mRNAs. Compelling evidence also suggests that both mRNA binding proteins and regulatory RNAs which participate to mRNA half-life regulation may be useful prognostic markers in breast cancers, pointing to a potential therapeutic approach to treatment of patients with these tumors. In this review, we summarize the main mechanisms involved in the regulation of mRNA decay and discuss the possibility of its implication in breast cancer aggressiveness and the efficacy of targeted therapy.

TRIM24 links glucose metabolism with transformation of human mammary epithelial cells

Tripartite motif 24 protein (TRIM24) is a plant homeodomain/bromodomain histone reader, recently associated with poor overall survival of breast-cancer patients. At a molecular level, TRIM24 is a negative regulator of p53 levels and a co-activator of estrogen receptor. However, the role of TRIM24 in breast tumorigenesis remains largely unknown. We used an isogenic human mammary epithelial cell (HMEC) culture model, derived from reduction mammoplasty tissue, and found that ectopic expression of TRIM24 in immortalized HMECs (TRIM24 iHMECs) greatly increased cellular proliferation and induced malignant transformation. Subcutaneous injection of TRIM24 iHMECs in nude mice led to growth of intermediate to high-grade tumors in 60-70% of mice. Molecular analysis of TRIM24 iHMECs revealed a glycolytic and tricarboxylic acid cycle gene signature, alongside increased glucose uptake and activated aerobic glycolysis. Collectively, these results identify a role for TRIM24 in breast tumorigenesis through reprogramming of glucose metabolism in HMECs, further supporting TRIM24 as a viable therapeutic target in breast cancer.

Variants of interleukin-16 associated with gastric cancer risk

AIM

We conducted a case-control matched study to investigate the role of IL-16 gene polymorphisms, rs4072111, rs1131445, rs4778889 and rs11556218, in the risk of gastric cancer in a Chinese population, also performing subgroup analysis by subsites.

METHODS

To test the hypothesis of involvement, we analyzed the four SNPs of IL16 in 347 cancer patients and 368 controls. Demographic data and other information were collected using a newly designed questionnaire. Genotyping of IL16 (rs4072111, rs1131445, rs4778889 and rs11556218) was performed in a 384-well plate format on the MassARRAY® platform.

RESULTS

In our study, we found the gastric cancer patients were more likely to be male and have a family history of cancer (P < 0.05). We found the rs4778889 CC and rs11556218 GG genotype was significantly associated with 1.97 and 1.84-fold increased risk of non-cardia gastric cancer, while we did not find significant association between the four IL-16 SNPs and cardia gastric cancer.

CONCLUSIONS

In conclusion, our study indicated that IL-16 rs4778889 CC and rs11556218 GG genotypes are associated with an increased risk of non-cardia gastric cancer in a Chinese population. Our results offer insights into the influence of IL-16 on development of gastric cancer.

Tristetraprolin represses estrogen receptor α transactivation in breast cancer cells

Estrogen receptor α (ERα) mediates the effects of 17β-estradiol (E2) in normal mammary gland, and it is a key participant in breast cancer tumor development. ERα transactivation activity is mediated by the synergistic interaction of two domains designated AF1 and AF2. The function of AF2 is to recruit coactivator and corepressor proteins that allow ERα to oscillate between the roles of transcriptional activator and repressor. In contrast, the mechanism responsible for AF-1 transcriptional activity is not completely understood. In this study, we identified tristetraproline (TTP) as a novel ERα-associated protein. TTP expression in MCF7 cells repressed ERα transactivation and reduced MCF7 cell proliferation and the ability of the cells to form tumors in a mouse model. We show that TTP transcriptional activity is mediated through its recruitment to the promoter region of ERα target genes and its interaction with histone deacetylases, in particular with HDAC1. TTP expression attenuates the coactivating activity of SRC-1, suggesting that exchange between TTP and other coactivators may play an important role in fine-tuning ERα transactivation. These results indicate that TTP acts as a bona fide ERα corepressor and suggest that this protein may be a contributing factor in the development of E2-dependent tumors in breast cancer.

Post-transcriptional control of cytokine gene expression in health and disease

Post-transcriptional control of cytokine gene expression is essential for rapid and transient response to stimuli and external stress. In health, post-transcriptional control is exerted by a number of trans-acting RNA-binding proteins and cis-acting sequence elements. These elements exist largely in the 3' untranslated region and comprise microRNA targets and notably AU-rich elements, and exert regulated mRNA decay and translation repression. Defects in this control can lead to increased and sustained production of pro-inflammatory mediators contributing to several chronic inflammatory disease and cancer states. This introduction to the Journal's special issue on the topic summarizes, in a non-comprehensive list, the types of RNA-binding protein and their target cytokines, and potential contributions to disease, and presents the highlights of the individual reviews.

Genetic variants in microRNA target sites of 37 selected cancer-related genes and the risk of cervical cancer

Objectives

Single nucleotide polymorphisms (SNPs) in putative microRNA binding sites (miRSNPs) modulate cancer susceptibility via affecting miRNA binding. Here, we sought to investigate the association between miRSNPs and cervical cancer risk.

Methods

We first genotyped 41 miRSNPs of 37 cancer-related genes in 338 patients and 334 controls (Study 1), and replicated the significant associations in 502 patients and 600 controls (Study 2). We tested the effects of miRSNPs on microRNA-mRNA interaction by luciferase reporter assay.

Results

Five SNPs displayed notable association with cervical cancer risk in Study 1. Only IL-16 rs1131445 maintained a significant association with cervical cancer (CT/CC vs. TT, adjusted OR = 1.51, P = 0.001) in Study 2. This association was more evident in the combined data of two studies (adjusted OR = 1.49, P = 0.00007). We also found that miR-135b mimics interacted with IL-16 3′-UTR to reduce gene expression and that the rs1131445 T to C substitution within the putative binding site impaired the interaction of miR-135b with IL-16 3′-UTR. An ELISA indicated that the serum IL-16 of patients with cervical cancer was elevated (vs. controls, P = 0.001) and correlated with the rs1131445 genotype. Patients who carried the rs1131445 C allele had higher serum IL-16 than non-carriers (P<0.001).

Conclusions

These results support our hypothesis that miRSNPs constitute a susceptibility factor for cervical cancers. rs1131445 affects IL-16 expression by interfering with the suppressive function of miR135b and this variant is significantly associated with cervical cancer risk.

Regulation of cellular processes by interleukin-16 in homeostasis and cancer

Interleukin-16 (IL-16) is generated as a precursor molecule that is cleaved by caspase-3 to produce a pro-IL-16 molecule that functions as a regulator of T cell growth, and a secreted peptide that functions as a CD4 and/or CD9 ligand for induction of cell motility and activation. IL-16 has been predominantly studied as a contributing factor in the orchestration of an immune response; however, more recently IL-16 bioactivity has been closely associated with the progression of a number of different cancers. While the association between IL-16 plasma levels and tumor progression has been reported for many types of cancer, the mechanism for IL-16 involvement has been partially elucidated for three of the cancer types, cutaneous T cell lymphoma (CTCL), multiple myeloma (MM), and breast cancer. The mechanism for promoting cell growth is different in each of these cancers and involves a sequence mutation in the pro-molecule facilitating decreased p27(KIP1) levels in CTCL; over expression of the secreted IL-16 molecule to induce proliferation in CTCL T cells, and plasma cells in MM; and increased secreted IL-16 acting to recruit CD4+ pro-tumor macrophages in breast cancer. This article will review the cellular process for generating IL-16, the biological activities for both the pro- and secreted forms of the protein, and then the mechanism by which these forms contribute to cancer progression. As a soluble cytokine the ability to reduce or eliminate IL-16 synthesis through siRNA approaches or bioactivity through the use of neutralizing antibody treatment may represent a novel therapeutic approach.