Mitochondrial genome transfer drives metabolic reprogramming in adjacent colonic epithelial cells promoting TGFß1-mediated tumor progression.

Although nontumor components play an essential role in colon cancer (CC) progression, the intercellular communication between CC cells and adjacent colonic epithelial cells (CECs) remains poorly understood. Here, we show that intact mitochondrial genome (mitochondrial DNA, mtDNA) is enriched in serum extracellular vesicles (EVs) from CC patients and positively correlated with tumor stage. Intriguingly, circular mtDNA transferred via tumor cell-derived EVs (EV-mtDNA) enhances mitochondrial respiration and reactive oxygen species (ROS) production in CECs. Moreover, the EV-mtDNA increases TGFß1 expression in CECs, which in turn promotes tumor progression. Mechanistically, the intercellular mtDNA transfer activates the mitochondrial respiratory chain to induce the ROS-driven RelA nuclear translocation in CECs, thereby transcriptionally regulating TGFß1 expression and promoting tumor progression via the TGFß/Smad pathway. Hence, this study highlights EV-mtDNA as a major driver of paracrine metabolic crosstalk between CC cells and adjacent CECs, possibly identifying it as a potential biomarker and therapeutic target for CC.

Tumour-associated macrophage-derived DOCK7-enriched extracellular vesicles drive tumour metastasis in colorectal cancer via the RAC1/ABCA1 axis.

BACKGROUND: Metastasis accounts for the majority of deaths among patients with colorectal cancer (CRC). Here, the regulatory role of tumour-associated macrophages (TAMs) in CRC metastasis was explored. METHODS: Immunohistochemical (IHC) analysis of the TAM biomarker CD163 was conducted to evaluate TAM infiltration in CRC. Transwell assays and an ectopic liver metastasis model were established to evaluate the metastatic ability of tumour cells. RNA sequencing (RNA-seq) and liquid chromatography-mass spectrometry (LC-MS) were applied to identify the differentially expressed genes and proteins in CRC cells and in TAM-derived extracellular vesicles (EVs). Cholesterol content measurement, a membrane fluidity assay and filipin staining were performed to evaluate cholesterol efflux in CRC cells. RESULTS: Our results showed that TAM infiltration is positively correlated with CRC metastasis. TAMs can facilitate the migration and invasion of MC-38 and CT-26 cells via EVs. According to the RNA-seq data, TAM-EVs increase cholesterol efflux and enhance membrane fluidity in CRC cells by regulating ABCA1 expression, thus affecting the motility of CRC cells. Mechanistically, DOCK7 packaged in TAM-EVs can activate RAC1 in CRC cells and subsequently upregulate ABCA1 expression by phosphorylating AKT and FOXO1. Moreover, IHC analysis of ABCA1 in patients with liver-metastatic CRC indicated that ABCA1 expression is significantly greater in metastatic liver nodules than in primary CRC tumours. CONCLUSIONS: Overall, our findings suggest that DOCK7 delivered via TAM-EVs could regulate cholesterol metabolism in CRC cells and CRC cell metastasis through the RAC1/AKT/FOXO1/ABCA1 axis. DOCK7 could thus be a new therapeutic target for controlling CRC metastasis.

Tumor-derived extracellular vesicles delivering TNF-α promotes colorectal cancer metastasis via the NF-kB/LAMB3/AKT axis by targeting SNAP23.

Accumulating evidence have demonstrated that cytokines are enriched in tumor-derived extracellular vesicles (EVs) and widely involved in tumorigenesis of various types of carcinomas, including colorectal cancer (CRC). Nevertheless, the functions of cytokines in EVs secreted from colorectal cancer cells remain largely unknown. In the present study, we found that TNF-α was elevated in EVs from CRC patient serum samples and CRC cell lines, of which the expression was associated with aggressive features of colorectal cancer. EV TNF-α secretion is dependent on synaptosome-associated protein 23 (SNAP23). Functional experiments revealed that EV TNF-α promotes CRC cell metastasis via the NF-κB pathway by targeting SNAP23. Mechanistically, SNAP23 was transcriptionally upregulated by EV TNF-α/NF-κB axis to enhance the expression of laminin subunit beta-3 (LAMB3), thereby activating the PI3K/AKT signaling pathway and consequently facilitate CRC progression. Based on our findings, we could conclude that EV TNF-α plays an oncogenic role in CRC progression through SNAP23, which in turn promotes EV TNF-α secretion, suggesting that EV TNF-α/SNAP23 axis may serve as a diagnostic biomarker and potential therapeutic target for CRC.

LncRNA MIR17HG promotes colorectal cancer liver metastasis by mediating a glycolysis-associated positive feedback circuit.

Glycolysis plays a crucial role in reprogramming the metastatic tumor microenvironment. A series of lncRNAs have been identified to function as oncogenic molecules by regulating glycolysis. However, the roles of glycolysis-related lncRNAs in regulating colorectal cancer liver metastasis (CRLM) remain poorly understood. In the present study, the expression of the glycolysis-related lncRNA MIR17HG gradually increased from adjacent normal to CRC to the paired liver metastatic tissues, and high MIR17HG expression predicted poor survival, especially in patients with liver metastasis. Functionally, MIR17HG promoted glycolysis in CRC cells and enhanced their invasion and liver metastasis in vitro and in vivo. Mechanistically, MIR17HG functioned as a ceRNA to regulate HK1 expression by sponging miR-138-5p, resulting in glycolysis in CRC cells and leading to their invasion and liver metastasis. More interestingly, lactate accumulated via glycolysis activated the p38/Elk-1 signaling pathway to promote the transcriptional expression of MIR17HG in CRC cells, forming a positive feedback loop, which eventually resulted in persistent glycolysis and the invasion and liver metastasis of CRC cells. In conclusion, the present study indicates that the lactate-responsive lncRNA MIR17HG, acting as a ceRNA, promotes CRLM through a glycolysis-mediated positive feedback circuit and might be a novel biomarker and therapeutic target for CRLM.

The loss of SHMT2 mediates 5-fluorouracil chemoresistance in colorectal cancer by upregulating autophagy.

5-Fluorouracil (5-FU)-based chemotherapy is the first-line treatment for colorectal cancer (CRC) but is hampered by chemoresistance. Despite its impact on patient survival, the mechanism underlying chemoresistance against 5-FU remains poorly understood. Here, we identified serine hydroxymethyltransferase-2 (SHMT2) as a critical regulator of 5-FU chemoresistance in CRC. SHMT2 inhibits autophagy by binding cytosolic p53 instead of metabolism. SHMT2 prevents cytosolic p53 degradation by inhibiting the binding of p53 and HDM2. Under 5-FU treatment, SHMT2 depletion promotes autophagy and inhibits apoptosis. Autophagy inhibitors decrease low SHMT2-induced 5-FU resistance in vitro and in vivo. Finally, the lethality of 5-FU treatment to CRC cells was enhanced by treatment with the autophagy inhibitor chloroquine in patient-derived and CRC cell xenograft models. Taken together, our findings indicate that autophagy induced by low SHMT2 levels mediates 5-FU resistance in CRC. These results reveal the SHMT2-p53 interaction as a novel therapeutic target and provide a potential opportunity to reduce chemoresistance.

MALAT1 sponges miR-106b-5p to promote the invasion and metastasis of colorectal cancer via SLAIN2 enhanced microtubules mobility.

BACKGROUND: The low expression of miR93/25 (members of miR-106b~25 cluster) promoted the invasion and metastasis of colon cancer cells, which predicted poor survival. However, the role of miR-106b-5p, the member of miR-106b~25 cluster, in colorectal cancer (CRC) remains unclear. METHODS: Bioinformatics methods were used to predict the potential pairs of lncRNA-miRNA-mRNA. In situ hybridization and qPCR were used to evaluate the expression of MALAT1 and miR-106b-5p in the paraffin-embedded normal and CRC tissues. Kaplan-Meier analysis with the log-rank test was used for survival analyses. Immunohistochemistry staining was applied to investigate the expression of SLAIN2. Fluorescence recovery after photobleaching assay was applied to observe the microtubule (MT) mobility. In vitro and in vivo invasion and metastasis assays were used to explore the function of MALAT1/miR-106b-5p/SLAIN2 in the progression of CRC. FINDINGS: miR-106b-5p was identified as a suppressor in CRC. Functionally, ectopic or silencing the expression of miR-106b-5p inhibited or promoted the invasion and metastasis of CRC cells in vitro and in vivo. The long non-coding RNA MALAT1 regulated the miR-106b-5p expression and further mediated the mobility of SLAIN2-related MTs by functioning as a competing endogenous RNA in vitro and in vivo, which resulted in the progression of CRC. Clinically, low miR-106b-5p expression predicted poor survival of CRC patients, especially in combination with high MALAT1/ SLAIN2 expression. INTERPRETATION: miR-106b-5p served as a suppressor in combination with MALAT1/miR-106b-5p/SLAIN2, which might be a group of potential prognostic biomarkers in the prognosis of CRC. FUND: This work was supported by National Program Project for Precision Medicine in National Research and Development Plan of China (2016YFC0905300), National Natural Science Foundation of China (81572930), National Key Research and Development Program of the Ministry of Science and Technology of China (2016YFC0905303, 2016YFC1303200), Beijing Science and Technology Program (D17110002617004), Non-profit Central Research Institute Fund of Chinese Academy of Medical Sciences (2018PT32012), CAMS Innovation Fund for Medical Sciences (CIFMS) (2016-I2M-1-001), Incentive Fund for Academic Leaders of Oncology Hospital, Chinese Academy of Medical Sciences (RC2016003), and Beijing Hope Run Special Fund from Cancer Foundation of China (LC2017A19). The project of Shanghai Jiaotong Univversity (YG2017QN30).

Long non-coding RNA HNF1A-AS1 mediated repression of miR-34a/SIRT1/p53 feedback loop promotes the metastatic progression of colon cancer by functioning as a competing endogenous RNA.

In recent years, accumulating evidence indicates that long noncoding RNAs (lncRNAs) have emerged as powerful influence factors in the progression of multiple malignancies. Dysregulation of lncRNA HNF1A-antisense 1 (HNF1A-AS1) has been reported in many types of human cancers, and studies on HNF1A-AS1 function in cancers revealed that HNF1A-AS1could act as either oncogene or tumor suppressor. Nevertheless, the functional involvement of HNF1A-AS1 in colon cancer remains unknown. In this study, we reported that HNF1A-AS1 was frequently upregulated in colon cancer tissues and associated with poor prognosis. Upregulated HNF1A-AS1 promoted colon cancer cell viability, migration and invasion both in vitro and in vivo. HNF1A-AS1 silencing impaired tumor growth and metastasis in xenograft model assay. Moreover, HNF1A-AS1 functioned as an oncogene in metastasis of colon cancer in part through serving as a competing endogenous RNA to modulate miRNA-34a expression, subsequently with repression of miR-34a/SIRT1/p53 feedback loop and activation of canonical Wnt signaling pathway. Our results demonstrated that HNF1A-AS1 mediated the metastatic progression of colon cancer in part through miR-34a/p53 signaling axis, and established its candidacy as a new prognostic biomarker and a potential novel therapeutic target.

miR-4775 promotes colorectal cancer invasion and metastasis via the Smad7/TGFß-mediated epithelial to mesenchymal transition.

BACKGROUND: Despite advancements in the diagnosis and treatment of colorectal cancer (CRC), many patients die because of tumor metastasis or recurrence. Therefore, identifying new prognostic markers and elucidating the mechanisms of CRC metastasis and recurrence will help to improve the prognosis of the disease. As dysregulation of microRNAs is strongly related to cancer progression, the aim of this study was to identify the role of miR-4775 in the prognosis of CRC patients and the underling mechanisms involved in CRC progression. METHODS: qPCR and in situ hybridization were used to evaluate the expression of miR-4775 in 544 pairs of paraffin-embedded normal and CRC tissues. Kaplan-Meier analysis with the log-rank test was used for survival analyses. Immunohistochemical staining was applied to investigate the expression of miR-4775-regulated Smad7/TGFß pathway-associated markers. In vitro and in vivo invasion and metastasis assays were used to explore the function of miR-4775 in the progression of CRC. RESULTS: miR-4775 was identified as a high-risk factor for CRC metastasis and recurrence, with high levels predicting poor survival among the 544 studied CRC patients. Furthermore, high miR-4775 expression promoted the invasion of CRC cells as well as metastasis and the epithelial to mesenchymal transition (EMT) via Smad7-mediated activation of TGFß signaling both in vitro and in vivo. Downregulating miR-4775 or overexpressing Smad7 reversed the tumor-promoting roles of miR-4775/Smad7/TGFß in vitro and in vivo. CONCLUSION: miR-4775 promotes CRC metastasis and recurrence in a Smad7/TGFß signaling-dependent manner, providing a new therapeutic target for inhibiting the metastasis or recurrence of the disease.

Long non-coding ribonucleic acid zinc finger antisense 1 promotes the progression of colonic cancer by modulating ZEB1 expression.

BACKGROUND AND AIM: Long non-coding RNA zinc finger antisense 1 (ZFAS1) is frequently amplified in hepatocellular carcinoma and promotes metastasis by increasing zinc finger E-box binding homeobox 1 (ZEB1), which can potentiate the progression of epithelial-to-mesenchymal transition (EMT). However, the expression pattern and role of ZFAS1 in colonic cancer remains unknown. The present study aimed to investigate the role of ZFAS1 and its clinical significance in colonic cancer. METHODS: Paired clinical colonic cancer tissue samples and clinicopathologic characteristics of 73 patients were analyzed. Quantitative real-time polymerase chain reaction analysis was used to evaluate expression levels of ZFAS1 in colonic cancer tissues, cell lines, and plasma. ZEB1 and EMT-related markers expression levels also were explored. Cell biology assays were used to explore the biologic consequences of ZFAS1 in regulating cell proliferation and invasion, as well as the roles in regulating EMT. RESULTS: Zinc finger antisense 1 was up-regulated in colonic cancer tissues compared with adjacent mucosa (P < 0.01), and its expression level was significantly correlated with TNM stage, vascular invasion, and lymph node metastasis (P < 0.05). ZFAS1 and ZEB1 were also increased in patients' plasma. Moreover, ZFAS1 promoted proliferation, invasion, and impeded apoptosis. Knockdown of ZFAS1 decreased expression of ZEB1 and increased the epithelial markers E-cadherin, ZO-1 while decreasing mesenchymal markers vimentin and N-cadherin. CONCLUSIONS: Long non-coding RNA ZFAS1 may function as an oncogene by modulating ZEB1 to induce EMT. Manipulation of ZFAS1 level may be a novel approach to suppress colonic cancer progression. In addition, ZFAS1 in plasma has the potential to be a diagnostic biomarker of colonic cancer.

The chromatin-remodeling enzyme BRG1 promotes colon cancer progression via positive regulation of WNT3A.

In this study, we aimed to elucidate the clinical significance and underlying mechanisms of BRG1 in colon cancer. In the clinical analysis, overexpression of BRG1 correlates with colon cancer progression in two cohorts (n = 191 and n = 75). Kaplan-Meier survival analysis revealed that BRG1 is a prognosis predictor for overall survival (P < 0.001) and disease-free survival (P = 0.001). Knocking down BRG1 expression significantly suppressed the proliferation and invasion in colon cancer cells. The expression pattern of WNT3A is consistent with BRG1 in colon cancer tissues and WNT3A expression was inhibited in BRG1 knockdown cells. In addition, restoring WNT3A expression rescues the inhibition of cell proliferation and invasion induced by BRG1. In this study, we demonstrate that BRG1 may contribute to colon cancer progression through upregulating WNT3A expression.

Histone deacetylase enzyme silencing using shRNAs enhances radiosensitivity of SW579 thyroid cancer cells.

The aim of the present study was to screen the enzymes that are associated with the radiosensitivity of SW579 thyroid cancer cells, and investigate whether radiation, combined with specific RNA interference on the screened enzymes, enhances radiosensitivity of SW579 thyroid cancer cells. Quantitative polymerase chain reaction (qPCR) was used to analyze epigenetic enzyme expression changes before and after radiotherapy, and four enzymes, histone deacetylase 1 (HDAC1), HDAC2, HDAC4 and HDAC6 were screened. Western blot analysis was performed to analyze the change in HDAC1, HDAC2, HDAC4 and HDAC6 protein expression following radiotherapy. Short hairpin RNA (ShRNA)­HDAC1, shRNA­HDAC2, shRNA­HDAC4 and shRNA­HDAC6 plasmids were constructed and SW579 cells were transfected with corresponding shRNA­HDACs. Reverse transcription­qPCR was used to detect whether downregulation of HDAC mRNAs had been effective. In addition, shRNA and shRNA negative control (NC) pools were established and transfected into the SW579 cells. The samples were divided into four groups; control, trichostatin A, shRNA pool and shRNA NC pool, to analyze the effective enhancement of specific shRNA on radiosensitivity in thyroid cancer cells. The morphological changes were observed in the SW579 cells, and the number of tumor cells decreased markedly in the shRNA pool group compared with that of the other three groups. Therefore, it was concluded that HDACs present a potential target for increasing the sensitivity of thyroid cancer cells to radiotherapy, and shRNA­HDAC interference combined with radiotherapy promotes the radiosensitivity of tumors.

Linc00152 Functions as a Competing Endogenous RNA to Confer Oxaliplatin Resistance and Holds Prognostic Values in Colon Cancer.

Long noncoding RNAs act as crucial regulators in plenty of human cancers, yet their potential roles and molecular mechanisms in chemoresistance are poorly understood. This study showed that a novel lncRNA, long intergenic noncoding RNA 152 (Linc00152 ), promoted tumor progression and conferred resistance to oxaliplatin (L-OHP)-induced apoptosis in vitro and in vivo. It antagonized chemosensitivity through acting as a competing endogenous RNA to modulate the expression of miR-193a-3p, and then erb-b2 receptor tyrosine kinase 4 (ERBB4). Knockdown of ERBB4 in colon cancer cells decreased AKT phosphorylation, which resulted in decreased L-OHP resistance. Consistent with above findings, the specific AKT signaling inhibitor and activator were used, respectively, which demonstrated that Linc00152 contributed to L-OHP resistance at least partly through activating AKT pathway. Further studies indicated that Linc00152 was increased and appeared to be an independent prognostic factor for decreased survival and increased disease recurrence in stage II and III colon cancer patients undergoing L-OHP-based chemotherapy after surgery. Collectively, our findings established Linc00152 as a candidate prognostic indicator of outcome and drug responsiveness in colon cancer patients, and the involvement of competing endogenous RNAs mechanism in Linc00152/miR-193a-3p/ERBB4/AKT signaling axis may provide a novel choice in the investigation of drug resistance.

MicroRNA-20a-5p promotes colorectal cancer invasion and metastasis by downregulating Smad4.

BACKGROUND: Tumor metastasis is one of the leading causes of poor prognosis for colorectal cancer (CRC) patients. Loss of Smad4 contributes to aggression process in many human cancers. However, the underlying precise mechanism of aberrant Smad4 expression in CRC development is still little known. RESULTS: miR-20a-5p negatively regulated Smad4 by directly targeting its 3'UTR in human colorectal cancer cells. miR-20a-5p not only promoted CRC cells aggression capacity in vitro and liver metastasis in vivo, but also promoted the epithelial-to-mesenchymal transition process by downregulating Smad4 expression. In addition, tissue microarray analysis obtained from 544 CRC patients' clinical characters showed that miR-20a-5p was upregulated in human CRC tissues, especially in the tissues with metastasis. High level of miR-20a-5p predicted poor prognosis in CRC patients. METHODS: Five miRNA target prediction programs were applied to identify potential miRNA(s) that target(s) Smad4 in CRC. Luciferase reporter assay and transfection technique were used to validate the correlation between miR-20a-5p and Smad4 in CRC. Wound healing, transwell and tumorigenesis assays were used to explore the function of miR-20a-5p and Smad4 in CRC progression in vitro and in vivo. The association between miR-20a-5p expression and the prognosis of CRC patients was evaluated by Kaplan-Meier analysis and multivariate cox proportional hazard analyses based on tissue microarray data. CONCLUSIONS: miR-20a-5p, as an onco-miRNA, promoted the invasion and metastasis ability by suppressing Smad4 expression in CRC cells, and high miR-20a-5p predicted poor prognosis for CRC patients, providing a novel and promising therapeutic target in human colorectal cancer.

High-level expression of P21-Cdc/Rac-activated kinase 7 is closely related to metastatic potential and poor prognosis of colon carcinoma.

P21 protein (Cdc42/Rac)-activated kinase 7 (PAK7) can promote neurite outgrowth, induce microtubule stabilization, and activate cell survival signaling pathways. PAK7 expression was found to increase with colon carcinoma progression, but the prognostic value, clinical significance, and underlying mechanisms have not been explored. In my study, the expression of PAK7 was up-related at both the transcriptional and the translational levels in colon tumors compared to that in adjacent normal colon tissue. Patients with PAK7-positive tumors had a lower rate of overall survival (OS) and metastasis-free survival (MFS) (log-rank test, P < 0.001). A Cox proportional hazards model showed that PAK7 expression was an independent prognostic factor for OS (hazard ration [HR], 2.08; 95% confidence interval [CI], 1.16-3.73; P = 0.004) and MFS (HR, 2.88; 95% CI, 1.53-5.42; P < 0.001) in patients with colon cancer. Patients with tumors that were over-expressing PAK7 experienced metastasis, and died within a significantly shorter time after surgery (P < 0.001). Knockdown of PAK7 by a specific short hairpin RNA (shRNA) significantly suppressed the progression of epithelial to mesechymal transition (EMT), migration, and invasion of colon cancer cells in vitro and tumor growth in vivo. However, overexpression of PAK7 significantly promoted these processes. These findings indicate that aberrant PAK7 expression is associated with the occurrence of metastasis and poor clinical outcomes of human colon cancer by promoting the EMT, and the assessment of PAK7 expression might be helpful in predicting metastasis and prognostication for patients with colon cancer.

DDA1 promotes stage IIB-IIC colon cancer progression by activating NFκB/CSN2/GSK-3ß signaling.

Conventional high-recurrence risk factors are not sufficient to predict post-operative risk of tumor recurrence or sensitivity to 5-fluorouracil (5-FU)-based chemotherapy for stage II colon cancer. DDA1, an evolutionarily conserved gene located at 19p13.11, may be involved in the activation of nuclear factor kappaB (NFκB). This study aimed to investigate whether DDA1 contributes to tumorigenesis and progression of stage II colon cancer via activation of the NFκB pathway. We found that positive expression of DDA1 alone or in combination with p65 nuclear translocation correlated with increased risk of tumor recurrence in patients with stage IIB-IIC colon cancer. DDA1 overexpression in colon cancer lines promoted cell proliferation, facilitated cell cycle progression, inhibited 5-FU-induced apoptosis, enhanced invasion, and induced the epithelial-mesenchymal transition. Suppression of DDA1 inhibited tumor progression, and reduced tumor growth in vivo. We also demonstrated that DDA1-mediated tumor progression is associated with the activation of the NFκB/COP9 signalosome 2(CSN2)/glycogen synthase kinase3ß (GSK3ß) pathway. These results indicate that DDA1 promotes colon cancer progression through activation of NFκB/CSN2/GSK3ß signaling. DDA1, together with NFκB activation status, may serve as a sensitive biomarker for tumor recurrence risk and prognosis in patients with stage IIB-IIC colon cancers.

Decreased MALL expression negatively impacts colorectal cancer patient survival.

The aim of the present study was to determine whether MALL expression is associated with colon cancer progression and patient survival. MALL mRNA expression was reduced in the tumor tissues of 70% of the colon cancer patients and 75% of the rectal cancer patients as compared to their normal tissues. MALL protein was also significantly reduced in the tumor tissues of colon cancer patients (P < 0.001). Increased LOH and methylation of MALL was observed in tumor tissues as compared to normal tissues. Reduced MALL expression was associated with vessin invasion, disease recurrence and metastasis or death (P ≤ 0.027). Furthermore, patients with MALL-negative tumors had significantly decreased overall survival (OS) and disease-free survival (DFS) (P < 0.008 and P < 0.011, respectively). Univariate analysis indicated that MALL expression was significantly associated with OS and DFS. Finally, overexpression of MALL suppressed HCT116 and SW480 cell proliferation and inhibited HCT116 migration. MALL may play a role in colorectal cancer progression as suppression of its expression in tumor tissues negatively impacts colorectal cancer patient survival. Further analyses are required to determine if reduced MALL expression is due to LOH and/or methylation.

LncRNA-ATB mediated E-cadherin repression promotes the progression of colon cancer and predicts poor prognosis.

BACKGROUND: Long non-coding RNA-activated by TGF-ß (lncRNA-ATB) promotes the invasion-metastasis cascade in hepatocellular carcinoma via downregulating E-cadherin (E-cad) and inducing epithelial-to- mesenchymal transition (EMT) and is clinically significant in human colon cancer. However, its molecular mechanisms in colon cancer progression remain unclear. This study aimed to elucidate the role of lncRNA-ATB and its clinical value in colon cancer. METHODS: Expression levels of lncRNA-ATB in colon cancer tissues and colon cancer cell lines were evaluated using quantitative real-time polymerase chain reaction. The clinicopathological significance and prognostic value of lncRNA-ATB were investigated, and roles of lncRNA-ATB in regulating E-cad and other EMT-related markers expression and colon cancer progression were evaluated in vitro. Expression levels of lncRNA-ATB and E-cad in human plasma were evaluated. RESULTS: Long non-coding RNA-activated by TGF-ß was upregulated in colon cancer tissues compared with adjacent mucosa (P < 0.001). LncRNA-ATB levels were also higher in metastatic cancer tissues (P < 0.001). Among the three highly invasive colon cancer cell lines, lncRNA-ATB levels were relatively higher with concurrent low levels of E-cad compared with levels in the three low-invasive cell lines. LncRNA-ATB expression correlated with pN stage (P < 0.01) and American Joint Committee on Cancer stage (P < 0.01). Striking differences were observed in overall survival and disease-free survival in cases with both high lncRNA-ATB expression and low E-cad expression. Reduction of lncRNA-ATB increased expression of epithelial markers E-cad, ZO-1, and decreased expression of mesenchymal markers ZEB1 and N-cadherin (N-cad), and significantly influenced colon cancer cell progression. Plasma lncRNA-ATB was upregulated in colon cancer patients one month after surgery (P < 0.05). CONCLUSIONS: Long non-coding RNA-activated by TGF-ß may act on colon tumorigenesis by suppressing E-cad expression and promoting EMT process, and lncRNA-ATB inhibition may provide a promising therapeutic option for suppressing colon cancer progression.

Elevated expression of Thoc1 is associated with aggressive phenotype and poor prognosis in colorectal cancer.

The THO complex 1 (Thoc1) is a nuclear matrix protein playing vital roles in transcription elongation and mRNA export. Recently, aberrant expression of Thoc1 has been reported in an increasing array of tumor types. However, the clinical significance of Thoc1 expression in colorectal cancer (CRC) is still unknown. The present study aimed to characterize the expression of Thoc1 in human CRC and evaluate its clinical significance. Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting analyses showed that the mRNA and protein expression of Thoc1 in CRC specimens was significantly higher than that in adjacent normal colon mucosae. Immunohistochemistry (IHC) was conducted to characterize the expression pattern of Thoc1 in 185 archived paraffin-embedded CRC specimens. Statistical analyses revealed that high levels of Thoc1 expression were associated with the clinical stages and tumor differentiation. CRC patients with high levels of Thoc1 expression had poorer overall-survival and disease-free survival, whereas those with lower levels of Thoc1 expression survived longer. Furthermore, multivariate Cox regression analyses demonstrated that Thoc1 expression remained an independent prognostic factor for increased disease recurrence and decreased survival. Our results suggest for the first time that Thoc1 is involved in the development and progression of CRC, and elevated expression of Thoc1 is associated with aggressive phenotype and poor prognosis in CRC. These findings may prove to be clinically useful for developing a new therapeutic target of CRC treatment.

Period 1 and estrogen receptor-beta are downregulated in Chinese colon cancers.

To investigate whether Period 1 (PER1) and Estrogen receptor-beta (ER2) are associated with occurrence and development of Chinese colorectal cancers. By using RT-quantitative PCR, tissue microarray (TMA) and immunohistochemistry, we detected mRNA levels and protein levels of PER1 and ER2 in the cancerous tissues and paired normal adjacent tissues in patients with colorectal cancer. Survival analyses were performed by the Kaplan-Meier method utilizing log-rank test and univariate and multivariate Cox proportional modeling to measure 5-year disease-free survival (DFS) and overall survival (OS). Real-time PCR showed that, the delta Ct value (tumor tissue vs. normal mucosa) of PER1 or ER2 is 8.51 ± 2.81 vs. 7.34 ± 2.08 or 12.39 ± 2.43 vs. 9.76 ± 1.75, expression of PER1 and ER2 decreased significantly in tumor tissues compared with noncancerous mucosas of patients with or without metastasis (both of P values <0.001). Spearman test revealed that PER1 and ER2 were significantly down-regulated in cancerous tissues (r=0.283; P<0.001) which was also confirmed by immunohistochemistry of specimens from 203 colon cancer patients in a TMA format. The reduction of PER1 was associated with gender and distant metastasis (P=0.037 and P<0.001, respectively) whereas the decline of ER2 was associated with age (P=0.043) by analyzing the clinical data. However, we were not capable of detecting any association between PER1 level or ER2 level and overall survival (OS) or disease free survival (DFS). It is the first observation of correlated reduction of PER1 and ER2 in Chinese colon cancers, and they do play a certain role in colorectal cancer.