Lidong Zu

IL-6 secreted by cancer-associated fibroblasts induces tamoxifen resistance in luminal breast cancer

Cancer-associated fibroblasts (CAFs) have been implicated in the development of resistance to anticancer drugs; however, the role and mechanism underlying CAFs in luminal breast cancer (BrCA) tamoxifen resistance are unclear. We found that stromal fibroblasts isolated from the central or peripheral area of BrCA have similar CAF phenotype and activity. In vitro and in vivo experiments showed that CAFs derived from clinical-luminal BrCAs induce tamoxifen resistance through decreasing estrogen receptor-α (ER-α) level when cultured with luminal BrCA cell lines MCF7 and T47D. CAFs promoted tamoxifen resistance through interleukin-6 (IL-6) secretion, which activates Janus kinase/signal transducers and activators of transcriptionxa0(JAK/STAT3) and phosphatidylinositol 3-kinase (PI3K)/AKT pathways in tumor cells, followed by induction of epithelial-mesenchymal transitionxa0and upregulation of E3 ubiquitin ligase anaphase-promoting complexxa010 activity, which targeted ER-α degradation through the ubiquitin-proteasome pathway. Inhibition of proteasome activity, IL-6 activity or either the JAK/STAT3 or PI3K/AKT pathways markedly reduced CAF-induced tamoxifen resistance. In xenograft experiments of CAFs mixed with MCF7 cells, CAF-specific IL-6 knockdown inhibited tumorigenesis and restored tamoxifen sensitivity. These findings indicate that CAFs mediate tamoxifen resistance through IL-6-induced degradation of ER-αxa0in luminal BrCAs.Oncogene advance online publication, 9 June 2014; doi:10.1038/onc.2014.158.

Dual Inhibition of PI3K and mTOR Mitigates Compensatory AKT Activation and Improves Tamoxifen Response in Breast Cancer

Everolimus, an mTOR inhibitor, showed great clinical efficacy in combination with tamoxifen, letrozole, or exemestane for the treatment of estrogen receptor-positive (ER+) breast cancer. However, its antitumor activity was shown to be compromised by a compensatory process involving AKT activation. Here, it was determined whether combining an additional PI3K inhibitor can reverse this phenomenon and improve treatment efficacy. In breast cancer cells (MCF-7 and BT474), everolimus inhibited the mTOR downstream activity by limiting phosphorylation of p70S6K and 4EBP1, which resulted in p-Ser473-AKT activation. However, addition of a LY294002, a PI3K inhibitor, to tamoxifen and everolimus treatment improved the antitumor effect compared with tamoxifen alone or the other two agents in combination. Moreover, LY294002 suppressed the activity of the PI3K/AKT/mTOR axis and mitigated the p-Ser473-AKT activation feedback loop in both cell lines. Critically, this combination scheme also significantly inhibited the expression of HIF-1a, an angiogenesis marker, under hypoxic conditions and reduced blood vessel sprout formation in vitro. Finally, it was shown that the three-agent cocktail had the greatest efficacy in inhibiting MCF-7 xenograft tumor growth and angiogenesis. Taken together, these results suggest that inhibition of PI3K and mTOR may further improve therapy in ER+ breast cancer cells. Implications: Combinatorial inhibition of the PI3K/AKT/mTOR signaling axis may enhance endocrine-based therapy in breast cancer. Mol Cancer Res; 11(10); 1269–78. ©2013 AACR.

HIC1 Silencing in Triple-Negative Breast Cancer Drives Progression through Misregulation of LCN2

The tumor suppressor gene HIC1 is frequently deleted or epigenetically silenced in human cancer, where its restoration may improve cancer prognosis. Here, we report results illuminating how HIC1 silencing alters effect or signals in triple-negative breast cancer (TNBC), which are crucial for its pathogenesis. HIC1 expression was silenced only in TNBC compared with other molecular subtypes of breast cancer. Restoring HIC1 expression in TNBC cells reduced cell migration, invasion, and metastasis, whereas RNAi-mediated silencing of HIC1 in untransformed human breast cells increased their invasive capabilities. Mechanistic investigations identified the small-secreted protein lipocalin-2 (LCN2), as a critical downstream target of HIC1 in TNBC cells. Elevating LCN2 expression in cells expressing HIC1 partially rescued its suppression of cell invasion and metastasis. Notably, autocrine secretion of LCN2 induced by loss of HIC1 activated the AKT pathway through the neutrophil gelatinase-associated lipocalin receptor, which is associated with TNBC progression. Taken together, our findings revealed that the HIC1-LCN2 axis may serve as a subtype-specific prognostic biomarker, providing an appealing candidate target for TNBC therapy.

Retraction Note to: IL-6 secreted by cancer-associated fibroblasts induces tamoxifen resistance in luminal breast cancer

The authors wish to retract this article due to concerns raised regarding some of the data presented in Figures 2, 4, 5, 6 and Supplementary Figures 6 and 7. According to the data presented in Figures 1, 3 and 7, the major conclusion drawn from this article is still valid: IL-6 secreted by CAFs is causal factor for tamoxifen resistance in luminal breast cancer.

The feedback loop between miR-124 and TGF-β pathway plays a significant role in non-small cell lung cancer metastasis.

Increasing evidence shows that micro RNAs (miRNAs) play a critical role in tumor development. However, the role of miRNAs in non-small cell lung cancer (NSCLC) metastasis remains largely unknown. Here, we found that miR-124 expression was significantly impaired in NSCLC tissues and associated with its metastasis. In vitro and in vivo experiments indicate that restoring miR-124 expression in NSCLC cells had a marked effect on reducing cell migration, invasion and metastasis. Mechanistic analyses show that Smad4, a cobinding protein in transforming growth factor-β (TGF-β) pathway, was identified as a new target gene of miR-124. Restoring Smad4 expression in miR-124-infected cells could partially rescue miR-124-induced abolition of cell migration and invasion. Notably, upon TGF-β stimulation, phosphorylation of Smad2/3 was modulated by alteration of miR-124 or Smad4 expression, followed by inducing some special transcription of downstream genes including Snail, Slug and ZEB2, all of which may trigger epithelial-mesenchymal transition and be associated with NSCLC metastasis. Moreover, activation of TGF-β pathway may enhance expression of DNMT3a, leading to hypermethylation on miR-124 promoter. Therefore, heavily loss of miR-124 expression further enhances Smad4 level by this feedback loop. Taken together, our data show for the first time that the feedback loop between miR-124 and TGF-β pathway may play a significant role in NSCLC metastasis. Targeting the loop may prove beneficial to prevent metastasis and provide a more effective therapeutic strategy for NSCLC.

Bmi-1 expression modulates non-small cell lung cancer progression

Previous studies indicate that the role of B lymphoma Mo-MLV insertion region 1 homolog (Bmi-1) is responsible for multiple cancer progression. However, Bmi-1 in controlling gene expression in non-small cell lung cancer (NSCLC) development is not well explored. Here we report that the Bmi-1 level is highly increased in primary NSCLC tissues compared to matched adjacent non-cancerous tissues and required for lung tumor growth in xenograft model. Furthermore, we also demonstrate that Bmi-1 level is lower in matched involved lymph node cancerous tissues than the respective primary NSCLC tissues. We find that Bmi-1 does not affect cell cycle and apoptosis in lung cancer cell lines as it does not affect the expression of p16/p19, Pten, AKT and P-AKT. Mechanistic analyses note that reduction of Bmi-1 expression inversely regulates invasion and metastasis of NSCLC cells in vitro and in vivo, followed by induction of epithelial-mesenchymal transition (EMT). Using genome microarray assays, we find that RNAi-mediated silence of Bmi-1 modulates some important molecular genetics or signaling pathways, potentially associated with NSCLC development. Taken together, our findings disclose for the first time that Bmi-1 level accumulates strongly in early stage and then declines in late stage, which is potentially important for NSCLC cell invasion and metastasis during progression.

HIC1 loss promotes prostate cancer metastasis by triggering epithelial-mesenchymal transition: HIC1 loss and prostate cancer metastasis

Metastatic disease is the leading cause of death due to prostate cancer (PCa). Although the hypermethylated in cancer 1 (HIC1) gene has been observed to be epigenetically modified in PCa, its intrinsic role and mechanism in PCa metastasis still remain uncertain. Here, we show that hypermethylation of the HIC1 promoter markedly reduces its suppressive function in metastatic PCa tissues as compared with primary and adjacent normal prostate tissues, and is associated with poor patient survival. PCas in cancer‐prone mice homozygous for a prostate‐targeted Hic1 conditional knockout showed stronger metastatic behaviour than those in heterozygous mice, as a result of epithelial–mesenchymal transition (EMT). Moreover, impairment of HIC1 expression in PCa cells induced their migration and metastasis through EMT, by enhancing expression of Slug and CXCR4, both of which are critical to PCa metastasis; the CXCL12–CXCR4 axis promotes EMT by activating the extracellular signal‐regulated kinase (ERK) 1/2 pathway. Taken together, our results suggest that evaluation of HIC1–CXCR4–Slug signalling may provide a potential predictor for PCa aggressiveness. Copyright

Hypermethylated in cancer 1(HIC1) suppresses non-small cell lung cancer progression by targeting interleukin-6/Stat3 pathway

Non-small cell lung cancer (NSCLC), which accounts for more than 80% of lung cancers, is a leading cause of cancer mortality worldwide. However, the mechanism underlying its progression remains unclear. Here we found that HIC1 promoter was heavily methylated in NSCLC cell lines and tissues contributing to its low expression compared to normal controls. Restoring HIC1 expression inhibited migration, invasion and promoted inducible apoptosis of NSCLC cells. Notably, HIC1 is a tumor suppressor through inhibiting the transcription of IL-6 by sequence-specific binding on its promoter. Restoring IL-6 expression could partially rescue these phenotypes induced by HIC1 in vitro and in vivo. Mechanistic analyses show that autocrine secretion of IL-6 induced by loss of HIC1 activated STAT3 through IL-6/JAK pathway and was associated with NSCLC progression. The HIC1/IL-6 axis may serve as a prognostic biomarker and provide an attractive therapeutic target for NSCLC.

Gastrin inhibits gastric cancer progression through activating the ERK-P65-miR23a/27a/24 axis

BackgroundTo test the hypothesis that activated extracellular signal-regulated kinase (ERK) regulates P65-miR23a/27a/24 axis in gastric cancer (GC) and the ERK-P65-miR23a/27a/24 axis plays an important role in the development of GC, and to evaluate the role of gastrin in GC progression and ERK-P65-miR23a/27a/24 axis.MethodsThe component levels of the ERK-P65-miR23a/27a/24 axis in four fresh GC tissues, 101 paraffin-embedded GC tissues and four GC cell lines were determined by Western blotting, immunohistochemistry (IHC) or qRT-PCR. The effects of gastrin on GC were first evaluated by measuring gastrin serum levels in 30 healthy and 70 GC patients and performing a correlation analysis between gastrin levels and survival time in 27 GC patients after eight years of follow-up, then evaluated on GC cell lines, GC cell xenograft models, and patient-derived xenografts (PDX) mouse models. The roles of ERK-P65-miR23a/27a/24 axis in GC progression and in the effects of gastrin on GC were examined.ResultsERK- P65-miR23a/27a/24 axis was proved to be present in GC cells. The levels of components of ERK-P65-miR23a/27a/24 axis were decreased in GC tissue samples and PGC cells. The decreased levels of components of ERK-P65-miR23a/27a/24 axis were associated with poor prognosis of GC, and ERK-P65-miR23a/27a/24 axis played a suppressive role in GC progression. Low blood gastrin was correlated with poor prognosis of the GC patients and decreased expression of p-ERK and p-P65 in GC tissues. Gastrin inhibited proliferation of poorly-differentiated GC (PGC) cells through activating the ERK-P65-miR23a/27a/24 axis. Gastrin inhibited GC growth and enhanced the suppression of GC by cisplatin in mice or PGC cell culture models through activating the ERK-P65-miR23a/27a/24 axis or its components.ConclusionsERK-P65-miR23a/27a/24 axis is down-regulated, leading to excess GC growth and poor prognosis of GC. Low gastrin promoted excess GC growth and contributed to the poor prognosis of the GC patients by down-regulating ERK-P65-miR23a/27a/24 axis. Gastrin inhibits gastric cancer growth through activating the ERK-P65-miR23a/27a/24 axis.

Overexpression of dedicator of cytokinesis 2 correlates with good prognosis in colorectal cancer associated with more prominent CD8+ lymphocytes infiltration: a colorectal cancer analysis: MIAO et al.

Recently, dedicator of cytokinesis 2 (DOCK2) has been reportedly exhibited high mutation prevalence in the Asian colorectal cancer (CRC) cohort. However, the expression pattern of DOCK2 and its clinical significance in CRC were still unknown. To characterize the role of DOCK2, a tissue microarray (TMA) containing 481 archived paraffin‐embedded CRC specimens was performed by immunohistochemistry. Among which, 54 primary CRC tissues showed high expression of DOCK2 protein, while others were negative. Moreover, DOCK2 expression was positively associated with invasion depth (Pu2009<u2009.001) and tumor size (Pu2009=u2009.016). Significantly, Kaplan‐Meier survival analysis revealed that patients with higher DOCK2 expression had a longer overall survival time (Pu2009=u2009.017). Furthermore, univariate and multivariate Cox regression analysis confirmed that DOCK2 is an independent prognostic marker in CRC (Pu2009=u2009.049,; HR, 0.519; 95% CI, 0.270 to 0.997). In addition, we observed a strong correlation between the infiltration of CD8+ T lymphocytes and DOCK2 expression (Pu2009=u2009.0119). Our findings demonstrated that overexpressed DOCK2 might involve in recruiting CD8+ T lymphocytes and serve as a novel prognostic indicator and indicated a potential therapeutic strategy by restoring DOCK2 for CRC.