C/EBP-β-activated microRNA-223 promotes tumour growth through targeting RASA1 in human colorectal cancer

Circulating Serum miRNAs as Diagnostic Markers for Colorectal Cancer

AIM

The study was designed to assess the possibility of using circulating miRNAs (serum miRNAs) as diagnostic biomarkers in colorectal cancer (CRC) and to identify their possibility as candidates for targeted therapy.

METHODS

The study involved two sample sets: 1- a training set which included 90 patients with colorectal related disease (30 with CRC, 18 with inflammatory bowel disease (IBD), 18 with colonic polyps (CP) and 24 with different colonic symptoms but without any colonoscopic abnormality who were enrolled as control group) and 2- a validation set which included 100 CRC patients. Serum miRNAs were extracted from all subjects to assess the expression profiles for the following miRNAs (miR-17, miR-18a, miR-19a, miR-19b, miR-20a, miR-21, miR-146a, miR-223, miR-24, miR-454, miR-183, miR-135a, miR- 135b and miR- 92a) using the custom miScript miRNA PCR-based sybergreen array. The area under the receiver operating characteristic curve (AUC) was used to evaluate the diagnostic performance of the studied miRNAs for colorectal cancer diagnosis.

RESULTS

Data analysis of miRNA from the training set showed that; compared to control group, only miR-19b was significantly up-regulated in patients with IBD group (fold change = 5.24, p = 0.016), whereas in patients with colonic polyps, miR-18a was significantly up-regulated (fold change = 3.49, p-value = 0.018). On the other hand, miR-17, miR-19a, miR-20a and miR-223 were significantly up-regulated (fold change = 2.35, 3.07, 2.38 and 10.35; respectively and p-value = 0.02, 0.015, 0.017 and 0.016; respectively in CRC patients. However, the validation set showed that only miR-223 was significantly up-regulated in CRC patients (fold change = 4.06, p-value = 0.04).

CONCLUSION

Aberrant miRNA expressions are highly involved in the cascade of colorectal carcinogenesis. We have found that (miR-17, miR-19a, miR-20a and miR-223) could be used as diagnostic biomarkers for CRC. On the other hand, miR-19b and miR-18a could be used as diagnostic biomarkers for CP and IBD respectively.

miR-663 overexpression induced by endoplasmic reticulum stress modulates hepatocellular carcinoma cell apoptosis via transforming growth factor beta 1

microRNAs are commonly dysregulated in a number of human cancers, for example, hepatocellular carcinoma (HCC), but the precise mechanism of dysregulation has not been extensively studied. Although previous studies have indicated that HCC cells are resistant to endoplasmic reticulum (ER) stress-induced apoptosis, little is known about the relationship between microRNAs and ER stress-mediated apoptosis resistance. In this study, we have demonstrated for the first time that the expression level of miR-663 was significantly upregulated in HCC cells co-incubated with tunicamycin, an ER stress inducer, as measured by a microRNA-chromatin immunoprecipitation microarray and quantitative real-time polymerase chain reaction; however, the effect of miR-663 on HCC cell apoptosis remains unknown. To investigate the potential involvement of miR-663 in HCC, HepG2 cells were transfected with mimics or inhibitors of miR-663. Consequently, we identified that downregulation of miR-663 suppressed HCC cell proliferation and promoted apoptosis under ER stress. Target gene analysis further predicted that the effects of miR-663 on HCC cells were mediated by directly targeting transforming growth factor beta 1 (TGFB1). Interestingly, the expression levels of TGFB1 changed inversely after downregulation or upregulation of miR-663 by inhibitors or mimics of miR-663 in HepG2 cells. Additionally, TGFB1 knockdown inhibited apoptosis in HepG2 cells. In sum, our study identifies a role for miR-663 as a critical regulator of ER stress-mediated apoptosis resistance in HCC cells via TGFB1. Accordingly, therapies aimed at the miR-663/TGFB1 axis might represent a hopeful strategy to overcome apoptosis resistance in HCC.

MicroRNA-Based Therapeutic Strategies for Targeting Mutant and Wild Type RAS in Cancer

MicroRNAs (miRs) have been causally implicated in the progression and development of a wide variety of cancers. miRs modulate the activity of key cell signaling networks by regulating the translation of pathway component proteins. Thus, the pharmacological targeting of miRs that regulate cancer cell signaling networks, either by promoting (using miR-supplementation) or by suppressing (using antisense oligonucleotide-based strategies) miR activity is an area of intense research. The RAS-extracellular signal regulated kinase (ERK) pathway represents a major miR-regulated signaling network that endows cells with some of the classical hallmarks of cancer, and is often inappropriately activated in malignancies by somatic genetic alteration through point mutation or alteration of gene copy number. In addition, recent progress indicates that many tumors may be deficient in GTPase activating proteins (GAPs) due to the collaborative action of oncogenic miRs. Recent studies also suggest that in tumors harboring a mutant RAS allele there is a critical role for wild type RAS proteins in determining overall RAS-ERK pathway activity. Together, these two advances comprise a new opportunity for therapeutic intervention. In this review, we evaluate miR-based therapeutic strategies for modulating RAS-ERK signaling in cancers; in particular for more direct modulation of RAS-GTP levels, with the potential to complement current strategies to yield more durable treatment responses. To this end, we discuss the potential for miR-based therapies focused on three prominent miRs including the pan-RAS regulator let-7 and the GAP regulator comprised of miR-206 and miR-21 (miR-206/21).