The cancer stem cell (CSC) hypothesis has gained significant recognition as a descriptor of tumorigenesis. Additionally, tumor‐associated macrophages (TAMs) are known to promote growth and metastasis ...of breast cancer. However, it is not known whether TAMs mediate tumorigenesis through regulation of breast CSCs. Here, we report that TAMs promote CSC‐like phenotypes in murine breast cancer cells by upregulating their expression of Sox‐2. These CSC‐like phenotypes were characterized by increased Sox‐2, Oct‐4, Nanog, AbcG2, and Sca‐1 gene expression, in addition to increased drug‐efflux capacity, resistance to chemotherapy, and increased tumorigenicity in vivo. Downregulation of Sox‐2 in tumor cells by siRNA blocked the ability of TAMs to induce these CSC‐like phenotypes and inhibited tumor growth in vivo. Furthermore, we identified a novel epidermal growth factor receptor (EGFR)/signal transducers and activators of transcription 3 (Stat3)/Sox‐2 paracrine signaling pathway between macrophages and mouse breast cancer cells that is required for macrophage‐induced upregulation of Sox‐2 and CSC phenotypes in tumor cells. We showed that this crosstalk was effectively blocked by the small molecule inhibitors AG1478 or CDDO‐Im against EGFR and Stat3, respectively. Therefore, our report identifies a novel role for TAMs in breast CSC regulation and establishes a rationale for targeting the EGFR/Stat3/Sox‐2 signaling pathway for CSC therapy. STEM CELLS2013;31:248–258
The altered metabolism and acidic microenvironment plays an important role in promoting tumor malignant characteristics. A small population of cancer stem cells (CSCs) were considered as a therapy ...target to reserve tumor relapse, resistance, and metastasis. However, the molecular mechanism that regulates CSCs metabolism remains poorly understood. In this study, we demonstrate a fundamental role of stemness gene LIN28B in maintaining CSCs glycolysis metabolism. Using LIN28B-expressing cancer cell lines, we found that the rate of extracellular acidification, glucose uptake, and lactate secretion are all suppressed by LIN28B knockdown in vitro and in vivo. Importantly, metabolic analyses reveal that CSCs have enhanced aerobic glycolysis metabolic characteristics and the glycolytic product lactate further promotes cancer associated stemness properties. LIN28B silencing suppresses MYC expression that further increases miR-34a-5p level. Furthermore, the glycolysis metabolism of human breast cancer cell line MDA-MB-231 is suppressed by either MYC siRNA or miR-34a-5p mimic. Clinically, high MYC and low miR-34a-5p level are correlated with high LIN28B expression and poor prognosis in human breast cancer patients. Notably, blocking LIN28B/MYC/miR-34a-5p signaling pathway by LIN28B-specific inhibitor causes dramatic inhibition of tumor growth and metastasis in immunodeficient orthotopic mouse models of human breast cancer cell MDA-MB-231. Taken together, our findings offer a preclinical investigation of targeting LIN28B to suppress CSCs glycolysis metabolism and tumor progression that may improve the therapeutic benefit for cancer patients.
ABSTRACT
Autophagy is one of the downstream effector mechanisms for elimination of intracellular microbes following activation of the Toll‐like receptors (TLRs). Although the detailed molecular ...mechanism for this cellular process is still unclear, Beclin 1, a key molecule for autophagy, has been suggested to play a role. Heat shock protein 90 (Hsp90) is a molecular chaperone that regulates the stability of signaling proteins. Herein, we show that Hsp90 forms a complex with Beclin 1 through an evolutionarily conserved domain to maintain the stability of Beclin 1. In monocytic cells, geldanamycin (GA), an Hsp90 inhibitor, effectively promoted proteasomal degradation of Beclin 1 in a concentration‐dependent (EC50 100 nM) and time‐dependent (t50 2 h) manner. In contrast, KNK437/Hsp inhibitor I had no effect. Hsp90 specifically interacted with Beclin 1 but not with other adapter proteins in the TLR signalsome. Treatment of cells with GA inhibited TLR3‐ and TLR4‐mediated autophagy. In addition, S. typhimurium infection‐induced autophagy was blocked by GA treatment. This further suggested a role of the Hsp90/Beclin 1 in controlling autophagy in response to microbial infections. Taken together, our data revealed that by maintaining the homeostasis of Beclin 1, Hsp90 plays a novel role in TLR‐mediated autophagy.—Xu, C., Liu, J., Hsu, L. ‐C., Luo, Y., Xiang, R., Chuang, T. ‐H. Functional interaction of Hsp90 and Beclin 1 modulates Toll‐like receptor‐mediated autophagy. FASEB J. 25, 2700‐2710 (2011). www.fasebj.org
Type 1 diabetic patients have lower counts of butyric acid-producing bacteria in the dysbiotic gut microbiome. In this study, we demonstrate that a butyric acid-producing Leuconostoc mesenteroides ...(L. mesenteroides) EH-1 strain isolated from Mongolian curd cheese can reduce blood glucose and IL-6 in the type 1 diabetic mouse model. L. mesenteroides EH-1 fermentation yielded high concentrations of butyric acid both in vitro and in vivo. Butyric acid or L. mesenteroides EH-1 increased the amounts of insulin in Min6 cell culture and streptozotocin (STZ)-induced diabetic mice. Inhibition or siRNA knockdown of free fatty acid receptor 2 (Ffar2) considerably reduced the anti-diabetic effect of probiotic L. mesenteroides EH-1 or butyric acid by lowering the level of blood glucose. We here demonstrate that Ffar2 mediated the effects of L. mesenteroides EH-1 and butryic acid on regulation of blood glucose and insulin in type 1 diabetic mice.
MicroRNAs have been reported to participate in tumorigenesis, treatment resistance, and tumor metastasis. Novel microRNAs need to be identified and investigated to guide the clinical prognosis or ...therapy for breast cancer.
The copy number variations (CNVs) of MIR3613 from Cancer Genome Atlas (TCGA) or Cancer Cell Line Encyclopedia (CCLE) were analyzed, and its correlation with breast cancer subtypes or prognosis was investigated. The expression level of miR-3613-3p in tumor tissues or serum of breast cancer patients was detected using in situ hybridization and qPCR. Gain-of-function studies were performed to determine the regulatory role of miR-3613-3p on proliferation, apoptosis, and tumor sphere formation of human breast cancer cells MDA-MB-231 or MCF-7. The effects of miR-3613-3p on tumor growth or metastasis in an immunocompromised mouse model of MDA-MB-231-luciferase were explored by intratumor injection of miR-3613-3p analogue. The target genes, interactive lncRNAs, and related signaling pathways of miR-3613-3p were identified by bioinformatic prediction and 3'-UTR assays.
We found that MIR3613 was frequently deleted in breast cancer genome and its deletion was correlated with the molecular typing, and an unfavorable prognosis in estrogen receptor-positive patients. MiR-3613-3p level was also dramatically lower in tumor tissues or serum of breast cancer patients. Gain-of-function studies revealed that miR-3613-3p could suppress proliferation and sphere formation and promote apoptosis in vitro and impeded tumor growth and metastasis in vivo. Additionally, miR-3613-3p might regulate cell cycle by targeting SMS, PAFAH1B2, or PDK3 to restrain tumor progression.
Our findings indicate a suppressive role of miR-3613-3p in breast cancer progression, which may provide an innovative marker or treatment for breast cancer patients.
Abstract
Different levels of regulatory mechanisms, including posttranscriptional regulation, are needed to elaborately regulate inflammatory responses to prevent harmful effects. Terminal ...uridyltransferase 7 (TUT7) controls RNA stability by adding uridines to its 3′ ends, but its function in innate immune response remains obscure. Here we reveal that TLR4 activation induces TUT7, which in turn selectively regulates the production of a subset of cytokines, including Interleukin 6 (IL-6). TUT7 regulates IL-6 expression by controlling ribonuclease Regnase-1 mRNA (encoded by
Zc3h12a
gene) stability. Mechanistically, TLR4 activation causes TUT7 to bind directly to the stem-loop structure on
Zc3h12a
3′-UTR, thereby promotes
Zc3h12a
uridylation and degradation.
Zc3h12a
from LPS-treated TUT7-sufficient macrophages possesses increased oligo-uridylated ends with shorter poly(A) tails, whereas oligo-uridylated
Zc3h12a
is significantly reduced in
Tut7
-/-
cells after TLR4 activation. Together, our findings reveal the functional role of TUT7 in sculpting TLR4-driven responses by modulating mRNA stability of a selected set of inflammatory mediators.
Immunotherapy using checkpoint blockade has revolutionized cancer treatment, improving patient survival and quality of life. Nevertheless, the clinical outcomes of such immunotherapy are highly ...heterogeneous between patients. Depending on the cancer type, the patient response rates to this immunotherapy are limited to 20-30%. Based on the mechanism underlying the antitumor immune response, new therapeutic strategies have been designed with the aim of increasing the effectiveness and specificity of the antitumor immune response elicited by checkpoint blockade agents. The activation of toll-like receptor 9 (TLR9) by its synthetic agonists induces the antitumor response within the innate immunity arm, generating adjuvant effects and priming the adaptive immune response elicited by checkpoint blockade during the effector phase of tumor-cell killing. This review first describes the underlying mechanisms of action and current status of monotherapy using TLR9 agonists and immune checkpoint inhibitors for cancer immunotherapy. The rationale for combining these two agents is discussed, and evidence indicating the current status of such combination therapy as a novel cancer treatment strategy is presented.
Macrophage accumulation and inflammation in the lung owing to stresses and diseases is a cause of lung cancer development. However, molecular mechanisms underlying the interaction between macrophages ...and cancer cells, which drive inflammation and stemness in cancers, are poorly understood. In this study, we investigated the expression of ubiquitin-specific peptidase 17 (USP17) in lung cancers, and role of elevated USP17 in the interaction between macrophages and lung cancer cells. USP17 expression in lung cancers was associated with poor prognosis, macrophage, and inflammatory marker expressions. Macrophages promoted USP17 expression in cancer cells. TNFR-associated factor (TRAF) 2-binding and TRAF3-binding motifs were identified in USP17, through which it interacted with and disrupted the TRAF2/TRAF3 complex. This stabilized its client proteins, enhanced inflammation and stemness in cancer cells, and promoted macrophage recruitment. In different animal studies, co-injection of macrophages with cancer cells promoted USP17 expression in tumors and tumor growth. Conversely, depletion of macrophages in host animals by clodronate liposomes reduced USP17 expression and tumor growth. In addition, overexpression of USP17 in cancer cells promoted tumor growth and inflammation-associated and stemness-associated gene expressions in tumors. These results suggested that USP17 drives a positive-feedback interaction between macrophages and cancer cells to enhance inflammation and stemness in cancer cells, and promotes lung cancer growth.
Lung cancer is the leading cause of cancer‐associated death, with a global 5‐year survival rate <20%. Early metastasis and recurrence remain major challenges for lung cancer treatment. The stemness ...property of cancer cells has been suggested to play a key role in cancer plasticity, metastasis and drug‐resistance, and is a potential target for drug development. In this study, we found that in non‐small cell lung cancer (NSCLC), BMI1 and MCL1 play crucial roles of cancer stemness including invasion, chemo‐resistance and tumour initiation. JNK signalling serves as a link between oncogenic pathway or genotoxicity to cancer stemness. The activation of JNK, either by mutant EGFR or chemotherapy agent, stabilized BMI1 and MCL1 proteins through suppressing the expression of E3‐ubiquitin ligase HUWE1. In lung cancer patient samples, high level of BMI1 is correlated with poor survival, and the expression of BMI1 is positively correlated with MCL1. A novel small‐molecule, BI‐44, was developed, which effectively suppressed BMI1/MCL1 expressions and inhibited tumour formation and progression in preclinical models. Targeting cancer stemness mediated by BMI1/MCL1 with BI‐44 provides the basis for a new therapeutic approach in NSCLC treatment.
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