miR-520h is crucial for DAPK2 regulation and breast cancer progression

Development of an anoikis-related gene signature and prognostic model for predicting the tumor microenvironment and response to immunotherapy in colorectal cancer

The effect of anoikis-related genes (ARGs) on clinicopathological characteristics and tumor microenvironment remains unclear. We comprehensively analyzed anoikis-associated gene signatures of 1057 colorectal cancer (CRC) samples based on 18 ARGs. Anoikis-related molecular subtypes and gene features were identified through consensus clustering analysis. The biological functions and immune cell infiltration were assessed using the GSVA and ssGSEA algorithms. Prognostic risk score was constructed using multivariate Cox regression analysis. The immunological features of high-risk and low-risk groups were compared. Finally, DAPK2-overexpressing plasmid was transfected to measure its effect on tumor proliferation and metastasis in vitro and in vivo. We identified 18 prognostic ARGs. Three different subtypes of anoikis were identified and demonstrated to be linked to distinct biological processes and prognosis. Then, a risk score model was constructed and identified as an independent prognostic factor. Compared to the high-risk group, patients in the low-risk group exhibited longer survival, higher enrichment of checkpoint function, increased expression of CTLA4 and PD-L1, higher IPS scores, and a higher proportion of MSI-H. The results of RT-PCR indicated that the expression of DAPK2 mRNA was significantly downregulated in CRC tissues compared to normal tissues. Increased DAPK2 expression significantly suppressed cell proliferation, promoted apoptosis, and inhibited migration and invasion. The nude mice xenograft tumor model confirmed that high expression of DAPK2 inhibited tumor growth. Collectively, we discovered an innovative anoikis-related gene signature associated with prognosis and TME. Besides, our study indicated that DAPK2 can serve as a promising therapeutic target for inhibiting the growth and metastasis of CRC.

circNFATC3 facilitated the progression of oral squamous cell carcinoma via the miR-520h/LDHA axis

The aim of this study was to verify the effects of circular RNA nuclear factor of activated T-cells, cytoplasmic 3 (circNFATC3), in oral squamous cell carcinoma (OSCC) development. The levels of circNFATC3, microRNA-520h (miR-520h), and lactate dehydrogenase A (LDHA) were measured by qRT-PCR and western blot analysis. The cellular functions were assessed by using commercial kits, MTT assay, EdU assay, flow cytometry analysis, and transwell assay. The interactions between miR-520h and circNFATC3 or LDHA were confirmed by dual-luciferase reporter assay. Finally, the mice test was enforced to evaluate the character of circNFATC3. We observed that the contents of circNFATC3 and LDHA were upregulated and miR-520h levels were downregulated in OSCC tissues compared with those in paracancerous tissues. For functional analysis, circNFATC3 knockdown repressed the cell glycolysis metabolism, cell proliferation, migration, and invasion, although it improved cell apoptosis in OSCC cells. LDHA could regulate the development of OSCC. circNFATC3 acted as a miR-520h sponge to modulate LDHA expression. In addition, the absence of circNFATC3 subdued tumor growth in vivo. In conclusion, circNFATC3 promoted the advancement of OSCC by adjusting the miR-520h/LDHA axis.

Hsa_Circ_0001860 Promotes Smad7 to Enhance MPA Resistance in Endometrial Cancer via miR-520h

Background: Medroxyprogesterone acetate (MPA) is one of the most commonly prescribed progestin for the treatment of endometrial cancer (EC). Despite initial benefits, many patients ultimately develop progesterone resistance. Circular RNA (circRNA) is a kind of noncoding RNA, contributing greatly to the development of human tumor. However, the role of circular RNA in MPA resistance is unknown.

Methods: We explored the expression profile of circRNAs in Ishikawa cells treated with (ISK/MPA) or without MPA (ISK) by RNA sequencing, and identified a key circRNA, hsa_circ_0001860. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used to verify its expression in MPA-resistant cell lines and tissues. CCK8, Transwell, and flow cytometry were used to evaluate the functional roles of hsa_circ_0001860 in MPA resistance. The interaction between hsa_circ_0001860 and miR-520 h was confirmed by bioinformatics analysis, luciferase reporter assay, and RNA pull-down assay.

Results: The expression of hsa_circ_0001860 was significantly downregulated in MPA-resistant cell lines and tissues, and negatively correlated with lymph node metastasis and histological grade of EC. Functional analysis showed that hsa_circ_0001860 knockdown by short hairpin RNA (shRNA) promoted the proliferation, inhibited the apoptosis of Ishikawa cells, and promoted the migration and invasion of Ishikawa cells treated with MPA. Mechanistically, hsa_circ_0001860 promoted Smad7 expression by sponging miR-520 h.

Conclusion: Hsa_circ_0001860 plays an important role in the development of MPA resistance in EC through miR-520h/Smad7 axis, and it could be targeted to reverse the MPA resistance in endometrial cancer.

MicroRNA-based potential diagnostic, prognostic and therapeutic applications in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a distinct subtype of breast cancer characterized by high recurrence rates and poor prognosis compared to other breast cancers. MicroRNAs (miRNAs) are small non-coding RNAs that regulate the expression of various post-transcriptional gene and silence a broad set of target genes. Many recent studies have demonstrated that miRNAs play an important role in the initiation, promotion, malignant conversion, progression, and metastasis of TNBC. Therefore, the aim of this review is to focus on recent advancements of microRNAs-based potential applications in diagnosis, treatment and prognosis of triple-negative breast cancer.

Brown Seaweed Fucoidan Inhibits Cancer Progression by Dual Regulation of mir-29c/ADAM12 and miR-17-5p/PTEN Axes in Human Breast Cancer Cells

In this study, we observed that brown seaweed fucoidan inhibited human breast cancer progression by upregulating microRNA (miR)-29c and downregulating miR-17-5p, thereby suppressing their target genes, a disintegrin and metalloproteinase 12 (ADAM12) and phosphatase and tensin homolog (PTEN), respectively. Moreover, fucoidan reduced the luciferase activity of 3'-untranslated region reporter; treatment of cells with the miR-29c mimic or miR-17-5p inhibitor also produced similar results. These effects of fucoidan inhibited the epithelial-mesenchymal transition in breast cancer cells, as evidenced by an increase in E-cadherin and a drop in N-cadherin, and inhibited breast cancer cell survival, as evidenced by the activation of the phosphoinositide 3-kinase/Akt pathway. Taken together, these findings demonstrate that fucoidan inhibits breast cancer progression by regulating the miR-29c/ADAM12 and miR-17-5p/PTEN axes. Fucoidan is a potential chemopreventive/chemotherapeutic agent for breast cancer.

MicroRNAs mediate therapeutic and preventive effects of natural agents in breast cancer

MicroRNAs (miRNAs) are a set of non-coding small RNA molecules that play a critical role in regulation of protein coding genes in cells. MiRNAs have been extensively studied as novel biomarkers, therapeutic targets, and new drugs in various human diseases. Breast cancer is a one of the leading tumor types significantly affecting women health worldwide. Over the past decade, a number of natural agents, such as paclitaxel and curcumin, have been applied for treatment and prevention of breast cancer due to their relatively low toxicity. However, the mechanisms of action have not been completely understood. Investigation on miRNAs is able to potentially provide a novel insight into better understanding the anticancer activities of these natural products. Given that a single miRNA can target multiple genes, theoretically, those genes involved in a certain phenotype can be clustered with one or a few miRNAs. Therefore, pleiotropic activities of natural agents should be interpreted by interactions between selected miRNAs and their targets. In this review, we summarize the latest publications related to the alterations of miRNAs by two natural agents (paclitaxel and curcumin) that are currently used in intervention of breast cancer, and conclude that the mechanism involving the regulation of miRNA expression is one of the keys to understand pleiotropic activities of natural agents.

MiR-302a/b/c/d cooperatively sensitizes breast cancer cells to adriamycin via suppressing P-glycoprotein(P-gp) by targeting MAP/ERK kinase kinase 1 (MEKK1)

BACKGROUND

The importance of individual microRNAs (miRNAs) in tumor has been established in different cancers. However, their association with tumor chemoresistance has not been fully understood. Previously, we found two novel MDR-associated microRNAs (miRNAs). In this report, we investigated the combined effects of miRNA gene cluster in chemoresistance of breast cancer.

METHODS

This study was performed in two different breast cancer cell lines (MCF-7 and MCF-7/ADR). The levels of miRNAs and mRNA expression were determined by using Quantitative Real-Time PCR. Western blotting was used to detect the levels of protein molecules. Cell viability was assessed by MTS assay. Bioinformatics and Luciferase reporter assay was performed to examine miRNA binding to the 3'-UTR of target genes.

RESULTS

The miR-302S family including miR-302a, miR-302b, miR-302c, and miR-302d was significantly down-regulated in P-glycoprotein (P-gp)-overexpressing MCF-7/ADR cells. Overexpression of miR-302 increased intracellular accumulation of ADR and sensitized breast cancer cells to ADR. Most importantly, miR-302S produced stronger effects than each individual member alone. The four miRNAs cooperatively downregulate P-gp expression in regulating drug sensitivity. However, our results showed that the suppression of P-gp expression by miR-302 is not through typical miRNA-mediated mRNA degradation but at the level of protein and transcription. Further studies identified MAP/ERK kinase kinase 1 (MEKK1) as a direct and functional target of miR-302. miR-302 showed combinatorial effects on MKEE1 repression and MEKK1-mediated ERK pathway. The suppression of P-gp by miR-302 was reversed by MEKK1 overexpression.

CONCLUSION

Our results indicate that miR-302 cooperatively sensitizes breast cancer cells to adriamycin via suppressing P-glycoprotein by targeting MEKK1 of ERK pathway. miR-302 gene cluster may be a potential target for reversing P-gp-mediated chemoresistance in breast cancer.