Biological factors driving colorectal cancer metastasis.

Approximately 20% of colorectal cancer (CRC) patients present with metastasis at diagnosis. Among Stage I-III CRC patients who undergo surgical resection, 18% typically suffer from distal metastasis within the first three years following initial treatment. The median survival duration after the diagnosis of metastatic CRC (mCRC) is only 9 mo. mCRC is traditionally considered to be an advanced stage malignancy or is thought to be caused by incomplete resection of tumor tissue, allowing cancer cells to spread from primary to distant organs; however, increasing evidence suggests that the mCRC process can begin early in tumor development. CRC patients present with high heterogeneity and diverse cancer phenotypes that are classified on the basis of molecular and morphological alterations. Different genomic and nongenomic events can induce subclone diversity, which leads to cancer and metastasis. Throughout the course of mCRC, metastatic cascades are associated with invasive cancer cell migration through the circulatory system, extravasation, distal seeding, dormancy, and reactivation, with each step requiring specific molecular functions. However, cancer cells presenting neoantigens can be recognized and eliminated by the immune system. In this review, we explain the biological factors that drive CRC metastasis, namely, genomic instability, epigenetic instability, the metastatic cascade, the cancer-immunity cycle, and external lifestyle factors. Despite remarkable progress in CRC research, the role of molecular classification in therapeutic intervention remains unclear. This review shows the driving factors of mCRC which may help in identifying potential candidate biomarkers that can improve the diagnosis and early detection of mCRC cases.

[Corrigendum) RNA interference­mediated FANCF silencing sensitizes OVCAR3 ovarian cancer cells to adriamycin through increased adriamycin­induced apoptosis dependent on JNK activation.

After the publication of the article, an interested reader drew to the authors' attention that there appeared to be a pair of overlapping data panels in Fig. 4C on p. 1726 [specifically, the 'Untransfected' and 'Control shRNA' data panels for the ADM (24 h) experiments]. The authors have consulted their original data, and have realized that this figure was inadvertently assembled incorrectly. Furthermore, they have noticed that Fig. 1 on p. 1724 also contained errors that arose during its assembly; essentially, several of the data panels in Fig. 1C, showing the detection of FANCD2 focus formation via immunofluorescence experiments, were selected inappropriately. The corrected versions of Figs. 1 and 4, containing the corrected data panels for Figs. 1C and 4C respectively, are shown on the next page. Note that these errors did not affect the results or the conclusions reported in this work. The authors all agree to this Corrigendum, and are grateful to the Editor of Oncology Reports for allowing them to have the opportunity to correct these mistakes. Lastly, the authors apologize to the readership for any inconvenience these errors may have caused. [Oncology Reports 29: 1721­1729, 2013; DOI: 10.3892/or.2013.2295].

[Corrigendum] MicroRNA-148a inhibits breast cancer migration and invasion by directly targeting WNT-1.

Subsequently to the publication of the above article, an interested reader drew to the authors' attention that the data panel for the MDA­MB­231/migration/NC experiment in Fig. 2B on p. 1428 was strikingly similar to the data shown for the MDA­MB­231/invasion/Blank experiment in Fig. 2C, such that these data appeared to have been derived from the same original source. The authors have referred back to their original data, and realize that the data panel was selected incorrectly for Fig. 2B. The corrected version of Fig. 2, showing the correct data for the MDA­MB­231/migration/NC experiment in Fig. 2B, is shown on the next page. The authors regret the error that was made during the preparation of this figure, and can confirm that the error in the assembly of this figure did not adversely affect the conclusions reported in the study. The authors are grateful to the Editor of Oncology Reports for allowing them the opportunity to publish a Corrigendum, and all the authors agree to this Corrigendum. Furthermore, they apologize to the readership for any inconvenience caused. [the original article was published in Oncology Reports 35: 1425­1432, 2016; DOI: 10.3892/or.2015.4502].

Upregulated expression of ACTL8 contributes to invasion and metastasis and indicates poor prognosis in colorectal cancer.

BACKGROUND: ACTL8 is a member of the CT antigens. There are only few studies on the role of ACTL8 in malignant tumors. The aim of this study is to investigate the expression and clinical significance of ACTL8 protein in colorectal cancer (CRC). MATERIALS AND METHODS: Human CRC tissues and cell lines, and paired adjacent non-tumor tissues and human intestinal epithelial cell lines were obtained to evaluate the expression of ACTL8. The association between protein expression of ACTL8 and clinicopathological parameters and prognosis of CRC patients was examined. The biological functions of ACTL8 in the invasion and metastasis of CRC were determined by wound healing and transwell invasion assays after silencing of ACTL8 in CRC cell lines. The potential target genes of ACTL8 were also identified by quantitative reverse transcription PCR and Western blotting after silencing of ACTL8 in CRC cell lines. RESULTS: It was found that ACTL8 was upregulated in human CRC tissues and cell lines. The expression of ACTL8 was positively associated with poor differentiation, invasion and metastasis, postoperative infection, and poor prognosis, but negatively associated with proximal margin length. In addition, silencing of ACTL8 significantly decreased the capacity of invasion and migration in HT29 and SW620 CRC cell lines. Moreover, silencing of ACTL8 significantly decreased the expression of TRIM29 in HT29 and SW620 CRC cell lines. CONCLUSION: These results suggest that ACTL8 plays a key role in the invasion and metastasis of CRC, and TRIM29 may be involved in the ACTL8-mediated poor prognosis of CRC.

Salinomycin induces selective cytotoxicity to MCF-7 mammosphere cells through targeting the Hedgehog signaling pathway.

Breast cancer stem cells (BCSCs) are believed to be responsible for tumor chemoresistance, recurrence, and metastasis formation. Salinomycin (SAL), a carboxylic polyether ionophore, has been reported to act as a selective breast CSC inhibitor. However, the molecular mechanisms underlying SAL-induced cytotoxicity on BCSCs remain unclear. The Hedgehog (Hh) signaling pathway plays an important role in CSC maintenance and carcinogenesis. Here, we investigated whether SAL induces cytotoxicity on BCSCs through targeting Hh pathway. In the present study, we cultured breast cancer MCF-7 cells in suspension in serum-free medium to obtain breast CSC-enriched MCF-7 mammospheres (MCF-7 MS). MCF-7 MS cells possessed typical BCSC properties, such as CD44+CD24-/low phenotype, high expression of OCT4 (a stem cell marker), increased colony-forming ability, strong migration and invasion capabilities, differentiation potential, and strong tumorigenicity in xenografted mice. SAL exhibited selective cytotoxicity to MCF-7 MS cells relative to MCF-7 cells. The Hh pathway was highly activated in BCSC-enriched MCF-7 MS cells and SAL inhibited Hh signaling activation by downregulating the expression of critical components of the Hh pathway such as PTCH, SMO, Gli1, and Gli2, and subsequently repressing the expression of their essential downstream targets including C-myc, Bcl-2, and Snail (but not cyclin D1). Conversely, Shh-induced Hh signaling activation could largely reverse SAL-mediated inhibitory effects. These findings suggest that SAL-induced selective cytotoxicity against MCF-7 MS cells is associated with the inhibition of Hh signaling activation and the expression of downstream targets and the Hh pathway is an important player and a possible drug target in the pathogenesis of BCSCs.

MicroRNA-148a inhibits breast cancer migration and invasion by directly targeting WNT-1.

Wnt/ß-catenin signaling pathway influences embryonic development, cell polarity and adhesion, apoptosis and tumorigenesis. MicroRNAs (miRNAs) function as important regulators of the tumorigenesis and metastasis. In the present study, we aimed to find novel targets and mechanisms of microRNA-148a (miR-148a) in regulating the migration and invasion of breast cancer cells. In the present study, miR-148a was found downregulated in human breast cancer tissues and cell lines. The ectopic miR-148a expression inhibited the migration and invasion of MCF-7 and MDA-MB-231 breast cancer cells. Furthermore, we demonstrated that WNT-1, one of the ligands of Wnt/ß-catenin signaling pathway, was a direct target of miR-148a. The overexpression of miR-148a reduced the mRNA and protein expression levels of WNT-1, also decreased the expression levels of the key components of Wnt/ß-catenin pathway, including ß-catenin, metalloproteinase-7 (MMP-7) and T-cell factor-4 (TCF-4) in MCF-7 and MDA-MB-231 cells. In addition, the data showed that the expression of WNT-1 was significantly higher in human breast cancer tissues compared with the adjacent normal tissues and the expression of miR-148a was negatively correlated with the WNT-1 expression in human breast cancer tissues. Taken together, our results suggest that miR-148a can suppress the migration and invasion of breast cancer cells by targeting WNT-1 and inhibiting Wnt/ß-catenin signaling pathway and this will provide new insights into the molecular mechanisms of breast cancer metastasis.

Overexpression of Rsf-1 correlates with pathological type, p53 status and survival in primary breast cancer.

AIM: The incidence of breast cancer in developing countries still increasing, to identify novel molecular markers associated with carcinogenesis and prognosis of breast cancer still being implemented. The largest subunit of Remodeling and spacing factor (RSF), Rsf-1, mediates ATPase-dependent chromatin remodeling. Its oncogenic properties have been demonstrated in certain carcinomas. The aim of this study was to examine the prognostic value of Rsf-1 in patients with primary breast carcinoma. METHODS: A total of 537 patients with primary breast cancer, and 54 with benign breast hyperplasia, were performed resection surgery in the same period were enrolled. Rsf-1 immunoexpression was retrospectively assessed by immunohistochemistry (IHC). As well as, it relationship with clinicopathological factors and patient survival (LRFS, DFS and OS) was investigated. RESULTS: Compared with benign breast hyperplasia tissues, higher percentage of Rsf-1 positive expression was detected in malignant breast carcinomas. Based on IHC staining extent × intensity scores and ROC analysis, 278 of 526 cancers (52.9%) had high-expression (cut-off values 2.5) of Rsf-1, which correlated significantly to pathologic subtypes of breast cancer (DCIS vs. IDC, P < 0.001; ILC vs. IDC, P = 0.036), bigger tumor size (P = 0.030), higher TNM stage (P = 0.044), and p53-positive expression. In addition, there was a trend that high-expression of Rsf-1 associated with younger age (P = 0.053). We further prove that combined positive-expression of Rsf-1 and p53 (Rsf-1 (+)/p53 (+)) was correlated with the bigger tumor size (P = 0.018), and higher TNM stage (P = 0.024). Kaplan-Meier survival analysis showed that Rsf-1 high-expression and combined positive-expression of Rsf-1 and p53 (Rsf-1 (+)/p53 (+)) exhibited a significant correlation with poor overall survival of patients with primary breast cancer, and no association has been identified in relation to LRFS or DFS. Especially, Univariate and multivariate survival analysis demonstrated Rsf-1 expression is an independent prognostic parameter for the overall survival of patients with breast cancer. CONCLUSIONS: High-expression of Rsf-1 is associated with pathologic subtypes of breast cancer, aggressive phenotype, p53 positive and poor clinical outcome, which confers tumor aggressiveness through chromatin remodeling, and targeting Rsf-1 gene and the pathway it related may provide new therapeutic avenues for treating breast cancer.

MiR-487a resensitizes mitoxantrone (MX)-resistant breast cancer cells (MCF-7/MX) to MX by targeting breast cancer resistance protein (BCRP/ABCG2).

Breast cancer resistance protein (BCRP/ABCG2) specifically transports various chemotherapeutic agents and is involved in the development of multidrug resistance (MDR) in cancer cells. MicroRNAs (miRNAs) can play an important role in modulating the sensitivity of cancer cells to chemotherapeutic agents. Therefore, after confirming that BCRP was increased in the mitoxantrone (MX)-resistant MCF-7 breast cancer cell line MCF-7/MX compared with its parental sensitive MCF-7 cell line, we aimed to explore the miRNAs that regulate BCRP expression and sensitize breast cancer cells to chemotherapeutic agents. In the present study, bioinformatic analysis indicated that miR-487a was one of the miRNAs that could bind to the 3' untranslated region (3'UTR) of BCRP. Quantitative RT-PCR (qRT-PCR) analysis demonstrated that the expression of miR-487a was reduced in MCF-7/MX cells, and a luciferase reporter assay demonstrated that miR-487a directly bound to the 3'UTR of BCRP. Moreover, ectopic miR-487a down-regulated BCRP expression at the mRNA and protein levels, increasing the intracellular accumulation and cytotoxicity of MX in resistant MCF-7/MX breast cancer cells. Meanwhile, inhibition of miR-487a increased BCRP expression at the mRNA and protein levels and induced MX resistance in sensitive MCF-7 breast cancer cells. Furthermore, the reduced expression of BCRP and increased antitumor effects of MX were also detected in MCF-7/MX xenograft tumors treated with the miR-487a agmir. Thus, our results suggested that miR-487a can directly regulate BCRP expression and reverse chemotherapeutic drug resistance in a subset of breast cancers.

RNA interference-mediated FANCF silencing sensitizes OVCAR3 ovarian cancer cells to adriamycin through increased adriamycin-induced apoptosis dependent on JNK activation.

In the present study, we downregulated FANCF expression by small interfering RNA (siRNA) in OVCAR ovarian cancer cells to address the effects of decreased FANCF expression on the function of the Fanconi anemia (FA)/breast cancer susceptibility gene (BRCA) pathway. Furthermore, we investigated whether this method increases the sensitivity of OVCAR3 cells to adriamycin (ADM) and the possible mechanism(s). We found that silencing of FANCF inactivated the FA/BRCA pathway by decreasing the monoubiquitination and focus formation of FANCD2 and reduced the function of the FA/BRCA pathway, resulting in the inhibition of cell proliferation, increased cell apoptosis and DNA damage in OVCAR3 cells. Moreover, we observed that silencing of FANCF enhanced the antiproliferative effect of ADM in OVCAR3 cells and increased ADM intracellular accumulation consequently sensitizing OVCAR3 cells to ADM. Furthermore, silencing of FANCF increased cell apoptosis of OVCAR3 cells which was caused by decreased mitochondrial membrane potential (MMP)-induced DNA damage, activated Jun N-terminal kinase (JNK), increased release of cytochrome c, increased expression of cleaved caspase-3 and poly(ADP-ribose) polymerase (PARP) dependent on JNK activation following treatment of ADM. Collectively, we confirm that silencing of FANCF sensitizes OVCAR3 ovarian cancer cells to ADM, suggesting that FANCF may serve as a potential target for therapeutic strategies in the treatment of ovarian cancer.

DNA repair genes XPC, XPG polymorphisms: relation to the risk of colorectal carcinoma and therapeutic outcome with Oxaliplatin-based adjuvant chemotherapy.

Xeroderma pigmentosum complementation group C and G (XPC, XPG) play important roles in DNA damage repairing machinery. Genetic variations in the XPC and XPG may be associated with increased risk for colorectal carcinoma (CRC). In this study, we evaluated the relation between the XPC Lys939Gln, XPG Asp1104His polymorphisms, and CRC susceptibility in a population-based case-control study, which included 1,028 CRC cases and 1,085 controls. Compared with the corresponding wild genotypes, we found that individuals with at least one copy of the XPC Lys939Gln (AC or CC genotype) and XPG Asp1104His (GC or CC genotype) had an increased risk for CRC. In addition, the variant genotypes of the XPC Lys939Gln AC/CC (P = 0.027) or XPG Asp1104His GC/CC (P = 0.003) reduced the elevation of preoperative carcinoembryonic antigen (CEA) level. Moreover a significantly longer progression-free survival (PFS) after Oxaliplatin-based adjuvant chemotherapy was observed in patients with XPG Asp1104His wide-type GG genotype (n = 432, Log-rank test: P = 0.033). Cox proportional hazards analyses demonstrated that variant genotypes of XPG Asp1104His [hazard ratio (HR) = 1.692, 95% confidence interval (95%CI): 1.202-2.383, P = 0.003] as well as pathology grade (HR = 2.545, 95%CI: 2.139-3.030, P < 0.001), and lymph node metastases (HR = 1.851, 95%CI: 1.306-2.625, P < 0.001) were predictive of shorter PFS for the CRC patients with Oxaliplatin-based adjuvant chemotherapy. In conclusion, the current data suggested that XPC Lys939Gln and XPG Asp1104His polymorphisms might contribute to the identification of patients with increased risk for CRC.