RARRES3 suppressed metastasis through suppression of MTDH to regulate epithelial-mesenchymal transition in colorectal cancer

It has been reported that Retinoic acid receptor responder 3 (RARRES3) could suppress the metastasis of colorectal cancer (CRC). However, the underlying mechanism by which RARRES3 suppresses metastasis remains unknown. To investigate the functional involvement of RARRES3 in CRC, we first analyzed the expression of this protein between human CRC clinical samples and their corresponding normal controls and tested its correlation with clinicopathology as well as prognosis of CRC. We also examined the endogenous expression of RARRES3 by western-blot in a panel of CRC cell lines with different metastatic capacity. Cell proliferation, migration and invation of the CRC cell lines with either knockdown or reexpression of RARRES3 were examined by MTT, transwell and wound healing assays, respectively. The intrecellular signaling pathways affected by manipulations of RARRES3 in CRC cells were determined by western blot. Immunoprecipitation (IP) was employed to assess the interactionbetween proteins. To investigate the metastatic ability in vivo, CRC cell lines with manipulations of RARRES3 expression were inoculated in nude mice through tail vein injection. We confirmed that RARRES3 was significantly down-regulated in CRC tissues compared with normal controls. RARRES3 expression was not correlated with prognosis but significantly associated with CRC differentiation and lymphnodes metastases. We also found that RARRES3 was able to significantly suppress the metastasis of CRC cells both in vitro and in vivo through the regulation of epithelial-mesenchymal transition (EMT) process during which RARRES3 interactedwith MTDH in an opposite way. Taken together, we for the first time found that RARRES3 was able to suppress the metastasis of CRC both in vitro and in vivo via suppression of MTDH so as to regulate EMT.     

The RING-H2 protein RNF11 is overexpressed in breast cancer and is a target of Smurf2 E3 ligase

The breast cancer-associated T2A10 clone was originally isolated from a cDNA library enriched for tumour messenger ribonucleic acids. Our survey of 125 microarrayed primary tumour tissues using affinity purified polyclonal antibodies has revealed that corresponding protein is overexpressed in invasive breast cancer and is weakly expressed in kidney and prostate tumours. Now known as RNF11, the gene encodes a RING-H2 domain and a PY motif, both of which mediate protein-protein interactions. In particular, the PPPPY sequence of RNF11 PY motif is identical to that of Smad7, which has been shown to bind to WW domains of Smurf2, an E3 ubiquitin ligase that mediates the ubiquitination and degradation of the TGFbeta receptor complex. Using various mutants of RNF11 in GST pulldown and immunoprecipitation assays, we found that RNF11 interacts with Smurf2 through the PY motif, leading to ubiquitination of both proteins. Smurf2 plays an active role in the repression of TGFbeta signalling, and our data indicate that overexpression of RNF11, through its interaction with Smurf2, can restore TGFbeta responsiveness in transfected cells.     

Effects of YAP1 and SFRP2 overexpression on the biological behavior of colorectal cancer cells and their molecular mechanisms

BackgroundColorectal cancer (CRC) is one of the most common malignancies worldwide and has a high mortality rate. With the development of tumor molecular biology, more and more attention is being paid to the mechanisms of cell pathways in colorectal carcinogenesis, such as the Hippo/Yes-associated protein 1 (YAP1) and Wnt/β-catenin signaling pathways. The abnormal expression of YAP1 and β-catenin have been reported in CRC, and can lead to excessive cell proliferation, and eventually, tumor formation. Secreted frizzled-related protein 2 (SFRP2) levels have been found to be decreased in a variety of cancers, and SFRP2 is an antagonist that binds directly to Wnt signal. At present, the molecular basis of colorectal tumors is still not fully understood. In the present study, we sought to identify the molecular mechanisms underlying YAP1 and SFRP2 in the development of CRC.MethodsWe constructed CRC cell lines that stably overexpressed YAP1 and SFRP2 using lentivirus packaging and cell infection. The levels of expression of the proteins were evaluated by western blot and immunofluorescence assays. Protein complex immunoprecipitation (Co-IP) was used to detect the interaction between YAP1, SFRP2, and β-catenin. The functional roles of YAP1 and SFRP2 in CRC was determined by a Cell Counting Kit-8 (CCK8) proliferation assay and flow cytometric apoptosis assay.ResultsThe data of the present study showed that the overexpression of SFRP2 promoted the expression of YAP1 and β-catenin protein, and the overexpression of YAP1 promoted the expression of β-catenin protein. YAP1 overexpression promoted cell proliferation, while SFRP2 overexpression inhibited cell proliferation and promoted cell apoptosis.ConclusionsOur findings showed that the expression of YAP1, SFRP2, and β-catenin is correlated in CRC cells. The Hippo pathway and Wnt pathway interact with each other in the pathogenesis of CRC, and YAP1 and SFRP2 are involved in the formation and development of CRC.     

Utility and specificity of plasma heat shock protein 90 alpha,CEA, and CA199 as the diagnostic test in colorectal cancer liver metastasis

BackgroundPlasma heat shock protein 90 alpha (Hsp90α) has been suggested as a novel biomarker for the diagnosis and prognosis of cancer. Carcinoembryonic antigen (CEA) and carbohydrate antigen199 (CA199) are traditional tumor biomarkers for colorectal cancer (CRC). Previous studies have shown that Hsp90α and the combination of Hsp90α and CEA are optimal biomarkers for CRC at an early stage. However, research on the use of Hsp90α alone or in combination with CEA and/or CA199 in diagnosing CRC development, particularly liver metastasis, is limited. This study sought to investigate the value of Hsp90α alone or in combination with CEA/CA199 in diagnosing CRC liver metastasis.MethodsThe clinical data of 472 CRC patients were retrospectively analyzed, which were confirmed by clinical manifestations and a histopathological examination associated with an imaging diagnosis. The levels of Hsp90α, and CEA, and CA199 were assessed by enzyme-linked immunoassays and electrochemiluminescence immunoassays. Liver metastasis was diagnosed by imaging or pathology of the liver. Logistic regression models were used to analyze associations between Hsp90α, CEA, and CA199, and liver metastasis in CRC. The areas under the curves (AUCs) were used to compare the utility of Hsp90α, CEA, and CA199 in the diagnosis of CRC liver metastasis (CRLM). Additionally, we compared the diagnostic utility of the models, including the Hsp90α plus 1 of the other serum markers, and a combination of the 3 serum makers.ResultsThe plasma levels of Hsp90α, CEA, and CA199 were positively associated with a higher risk of CRLM [odds ratios (OR) ranging from 1.36–2.72]. The AUCs of CEA, CA199, and Hsp90α for CRLM were 0.80, 0.69, and 0.55, respectively. The AUCs for the combination of Hsp90α and CEA, combination of Hsp90α and CA199, combinations of Hsp90α, CEA, and CA199 were 0.75, 0.66, 0.76, respectively. The combination of Hsp90α, CEA, and CA199 did not improve the diagnostic utility for liver metastasis in CRC.ConclusionsThe level of Hsp90α was elevated in CRC and was associated with CRLM. Thus, the Hsp90α is a potential biomarker for CRLM. CEA has the largest diagnostic utility for CRLM. Adding Hsp90α to CEA/CA199 did not improve their diagnostic utility for CRLM.     

AKT inhibits the phosphorylation level of H2A at Tyr57 via CK2α to promote the progression of gastric cancer

BackgroundHistone H2A and its variants have an important effect on DNA damage repair and cancer development. Protein kinase B (AKT) can regulate various cellular functions and play critical roles in the progression of different cancers. However, the interaction mechanism of H2A with AKT in gastric cancer (GC) has not been reported. A series of experiments were carried out in the present study to investigate this issue.MethodsFirstly, we used western blot and immunoprecipitation assays to determine the correlation between AKT and H2A, then detected the relationship between AKT and protein kinase CK2α that can phosphorylate H2A at Tyr57 site (H2A^Y57), and next examined the interaction among AKT, CK2α, and H2A in SNU-16 cells. Subsequently, the effect of these molecules on the cellular proliferation, migration, and invasion was measured by Cell Counting Kit-8 (CCK-8), wound healing, and transwell invasion assays.ResultsOur study preliminarily found that AKT was negatively correlated with H2A phosphorylation at the Tyr 57 site (H2A^Y57p). It was revealed that AKT mediated the phosphorylation of CK2α at the T13 site, which decreased the affinity of CK2α with its substrate histone H2A and inhibited the level of H2A^Y57p in GC cells. Furthermore, AKT-mediated CK2α phosphorylation promoted the proliferation, migration, and invasion of SNU-16 cells possibly through downregulating H2A^Y57p level.ConclusionsThese findings contribute to understanding the interactions among AKT, CK2α, and H2A in GC, and provide the potential biomarkers for the diagnosis and treatment of GC.     

PGK1-coupled HSP90 stabilizes GSK3β expression to regulate the stemness of breast cancer stem cells

Objective: Glycogen synthase kinase-3β(GSK3β) has been recognized as a suppressor of Wnt/β-catenin signaling, which is critical for the stemness maintenance of breast cancer stem cells. However, the regulatory mechanisms of GSK3β protein expression remain elusive.Methods: Co-immunoprecipitation and mass spectral assays were performed to identify molecules binding to GSK3β, and to characterize the interactions of GSK3β, heat shock protein 90(Hsp90), and co-chaperones. The role of PGK1 in Hsp90 ch...     

Radiation engenders converse migration and invasion in colorectal cancer cells through opposite modulation of ANXA2/AKT/GSK3β pathway

Radiation therapy is an effective non-surgical means to achieve local control for various solid tumors including colorectal cancer (CRC), but metastasis and recurrences after conventional radiotherapy remains a major obstacle in clinical practice, and the knowledge concerning the changes of metastatic potential after heavy ion radiation is still limited. This study investigated how radiation, including γ- and carbon ion radiation, would change the metastatic capacity of two CRC cell lines, HCT116 and DLD-1, and examined the underlying molecular mechanisms. We found that the migration and invasion was enhanced in DLD-1 cells but impaired in HCT116 cells in vitro and in vivo after radiation of γ-rays or carbons, and radiation induced epithelial mesenchymal transition (EMT) in DLD-1 cells but mesenchymal epithelial transition (MET) in HCT116 cells. The expression of snail, a key inducer of EMT, was significantly enhanced by inhibition of glycogen synthase kinase-3β (GSK3β) in both cell lines, suggesting the modulation of snail was alike in the two CRC cell lines. However, radiation inactivated GSK3β through stimulating the phosphorylation of AKT and GSK3β at Ser473 and Ser9 in DLD-1 cells respectively, but activated GSK3β by decreasing the expression of pAKT^Ser473 and pGSK3β^Ser9 or increasing the phosphorylation of GSK3β at Tyr216 in HCT116 cells. Therefore, the above inverted motility changes was due to the opposite modulation of AKT/GSK3β signaling pathway by radiation, which was further verified in other type of cancer cell lines including MCF-7, U251 and A549 cells. Moreover, it was found that annexin A2 (ANAX2) directly bound with GSK3β and acted as a negative regulator of GSK3β upon radiation. Knocking-down ANXA2 gene reversed the enhanced migration of the irradiated DLD-1 cells and strengthened radiation-impaired migration of HCT116 cells. Collectively, this study reveals that the change of cellular motility after radiation is independent of radiation type but is correlated with the inherent of cells.     

Tumor‐associated macrophage‐derived transforming growth factor‐β promotes colorectal cancer progression through HIF1‐TRIB3 signaling

Tumor‐associated macrophages (TAMs), one of the most common cell components in the tumor microenvironment, have been reported as key contributors to cancer‐related inflammation and enhanced metastatic progression of tumors. To explore the underlying mechanism of TAM‐induced tumor progression, TAMs were isolated from colorectal cancer patients, and the functional interaction with colorectal cancer cells was analyzed. Our study found that coculture of TAMs contributed to a glycolytic state in colorectal cancer, which promoted the stem‐like phenotypes and invasion of tumor cells. TAMs produced the cytokine transforming growth factor‐β to support hypoxia‐inducible factor 1α (HIF1α) expression, thereby upregulating Tribbles pseudokinase 3 (TRIB3) in tumor cells. Elevated expression of TRIB3 resulted in activation of the β‐catenin/Wnt signaling pathway, which eventually enhanced the stem‐like phenotypes and cell invasion in colorectal cancer. Our findings provided evidence that TAMs promoted colorectal cancer progression in a HIF1α/TRIB3‐dependent manner, and blockade of HIF1α signals efficiently improved the outcome of chemotherapy, describing an innovative approach for colorectal cancer treatment.     

PRRX1 promotes colorectal cancer stemness and chemoresistance via the JAK2/STAT3 axis by targeting IL-6

BackgroundStemness acquirement is one of the hallmarks of cancer and the major reason for the chemoresistance and poor prognosis of colorectal cancer (CRC). Previous research has revealed the stimulatory role of paired related homeobox 1 (PRRX1) on CRC metastasis. However, the role of PRRX1 in stemness acquirement and chemoresistance of CRC is still not clear.MethodsA retrospective cohort study was performed to investigate the relationship between PRRX1 expression and multiple clinicopathological characteristics of CRC patients. The functional effects of PRRX1 on stemness and chemoresistance of CRC cells were validated by in vitro and in vivo assays. Gene set enrichment analysis (GSEA) and JASPAR software were performed to predict the underlying mechanisms. Enzyme-linked immunosorbent assay (ELISA), Western blot, immunofluorescence, and dual-luciferase reporter assays were used to confirm the PRRX1-mediated signaling and its downstream factors.ResultsThe expression of PRRX1 was up-regulated in CRC tissues and cell lines compared to normal epithelial tissues and cell lines. High expression of PRRX1 was tightly associated with the metastasis, chemoresistance, and poor prognosis of CRC patients. Additionally, PRRX1 significantly promoted the proliferation, viability, stemness, and chemoresistance of CRC cells, as well as the activation of the interleukin-6 (IL-6)/JAK2/STAT3 axis. Inhibiting the expression of IL-6 dramatically eliminated the effects of PRRX1 on CRC cell stemness and chemoresistance.ConclusionsPRRX1 plays a vital role in the stemness and chemoresistance of CRC cells via JAK2/STAT3 signaling by targeting IL-6. Further, PRRX1 may be a valid biomarker for predicting the effect of chemotherapy and prognosis of CRC patients.     

Estradiol downregulation of the tumor suppressor gene BTG2 requires estrogen receptor‐α and the REA corepressor

B‐cell Translocation Gene 2 (BTG2/TIS21/PC3) is an anti‐proliferative tumor suppressor gene whose expression is significantly reduced in breast carcinomas, and in MCF‐7 and T‐47D breast cancer cell lines treated with estradiol (E2). In this study the mechanisms involved in E2 down regulation of BTG2 gene expression were examined. Depletion of ERα by siRNA indicated that the receptor is required for E2 down regulation of BTG2 mRNA levels, and cycloheximide experiments indicated that the effect of E2 on BTG2 expression was independent of intermediary protein synthesis. Chromatin immunoprecipitation analyses revealed that ERα interacts with the BTG2 promoter in a ligand‐independent fashion whereas transfection experiments indicated that ERα's DNA and ligand binding domains are required for E2 repression of BTG promoter activity. Surprisingly, histone deacetylase (HDACs) activity is essential for basal expression as evidenced by trichostatin A inhibition of BTG2 mRNA levels. Estradiol treatment did not alter histone H3 acetylation although it did induce displacement of RNA polymerase II from the BTG2 gene. Depletion of the ER specific corepressor REA (Repressor of Estrogen Receptor Activity) significantly abrogated E2‐mediated BTG2 repression. Taken together, our results reveal a requirement of HDAC activity for basal BTG2 expression and the ERα‐REA interaction for estrogen repression of the BTG2 gene. The ability of E2‐bound ERα and REA to suppress BTG2 expression indicates a positive role for this corepressor in regulation of breast cancer cell proliferation. © 2008 Wiley‐Liss, Inc.     

Mortalin maintains breast cancer stem cells stemness via activation of Wnt/GSK3β/β-catenin signaling pathway

Previous research indicated that mortalin overexpressed in breast cancer and contributed to carcinogenesis. Mortalin was also demonstrated to promote Epithelial-mesenchymal transition (EMT) and was considered as a factor for maintaining the stemness of the cancer stem cells. However, the underlying mechanisms about mortalin maintaining the stemness of breast cancer stem cells (BCSCs) remain unclear. Here, we identified that increased expression of mortalin in breast cancer was associated with poorer overall survival rate. Mortalin was elevated in breast cancer cell lines and BCSC-enriched populations. Additionally, knockdown of mortalin significantly inhibited the cell proliferation, migration and EMT, as well as sphere forming capacity and stemness genes expression. Further study revealed that mortalin promoted EMT and maintained BCSCs stemness via activating the Wnt/GSK3β/β-catenin signaling pathway in vivo and in vitro. Taken together, these findings unveiled the mechanism of mortalin in maintaining and regulating the stemness of BCSCs, and may offer novel therapeutic strategies for breast cancer treatment.     

bFGF-mediated phosphorylation of δ-catenin increases its protein stability and the ability to induce the nuclear redistribution of β-catenin

Recently, we have shown that δ-catenin strengthened the epidermal growth factor receptor (EGFR)/Erk1/2 signaling pathway through the association between EGFR and δ-catenin. Now, we further analyzed the correlation between basic fibroblast growth factor (bFGF)/fibroblast growth factor receptor 1 (FGFR1) and δ-catenin in prostate cancer and investigated the molecular mechanism underlying the role of bFGF/FGFR1 modulation in CWR22Rv-1 (Rv-1) cells. Here, we demonstrated that bFGF phosphorylated the tyrosine residues of δ-catenin in Rv-1 cells and further proved that the bFGF mediated FGFR1/δ-catenin tyrosine phosphorylation was time dependent. Furthermore, we demonstrated that bFGF stabilized the expression of δ-catenin through weakening its association with GSK3β and enhancing its stability to induce β-catenin into the nuclear by strengthening the processing of E-cadherin. In a word, these results indicated that bFGF/FGFR1 signaling pathway could enhance the tumor progression of prostate cancer via δ-catenin.