CircRNA hsa_circ_0070934 functions as a competitive endogenous RNA to regulate HOXB7 expression by sponging miR‑1236‑3p in cutaneous squamous cell carcinoma

Circ_0070934 promotes MGAT3 expression and inhibits epithelial-mesenchymal transition in bronchial epithelial cells by sponging miR-199a-5p

BACKGROUND

Circular RNA (circRNA) has the potential to serve as a crucial regulator in the progression of bronchial asthma. The objective of this investigation was to elucidate the functional dynamics of the circ_0070934/miR-199a-5p/Mannoside acetylglucosaminyltransferase 3 (MGAT3) axis in the development of asthma.

METHODS

Circ_0070934, miR-199a-5p and MGAT3 in peripheral venous blood of 38 asthmatic patients and 43 healthy controls were detected by qRT-PCR, and the expression of MGAT3 protein was examined by ELISA. The GSE148000 dataset was analyzed for differences in MGAT3. The BEAS-2B cells were transfected with circ_0070934 plasmid and small interfering RNA, miR-199a-5p mimics and inhibitors. The apoptosis level was detected by flow cytometry and MGAT3 was detected by qRT-PCR and Western blot. The expression of E-cadherin, N-cadherin, Vimentin was examined by Western blot. Interleukin-4 (IL-4) and IL-13 were used to co-stimulate BEAS-2B cells as an asthmatic airway epithelial cell model. BEAS-2B cells exposed to type 2 cytokines (IL-4 and IL-13) were treated with circ_0070934 plasmid, and the expression of E-cadherin, N-cadherin, and Vimentin was detected by Western blot. The binding relationships were verified using dual-luciferase reporter assay and miRNA pull-down assay.

RESULTS

The expression of circ_0070934 and MGAT3 in peripheral venous blood of asthmatic patients was down-regulated, and the expression of miR-199a-5p was up-regulated. And the expression of MGAT3 was reduced in sputum of asthma patients. Down-regulating the expression of circ_0070934 could promote apoptosis of BEAS-2B cells and increase epithelial-mesenchymal transition (EMT), and this effect can be partially reversed by down-regulating miR-199a-5p. Circ_0070934 could inhibit the process of epithelial mesenchymal transition induced by IL-4 and IL-13 in BEAS-2B cells. In addition, miR-199a-5p could respectively bind to circ_0070934 and MGAT3.

CONCLUSION

The findings of this study indicate that circ_0070934 may function as a competitive endogenous RNA (ceRNA) of miR-199a-5p, thereby modulating the expression of MGAT3 and impacting the process of EMT in bronchial epithelial cells. These results contribute to the establishment of a theoretical framework for advancing the prevention and treatment strategies for asthma.

MiR-1236: Key controller of tumor development and progression: Focus on the biological functions and molecular mechanisms

Combating with the cancer, as one of the leading causes of morbidity and mortality worldwide, scientific community extensively evidenced microRNA 1236 (miR-1236) roles in the pathogenesis of malignant tumors. It has been mentioned that miR-1236 target genes and signal pathways that are key controller of tumor development and progression. Consistently, increasing evidence reports that miR-1236 participates in cancer cell growth, migration, invasion, apoptosis, and drug resistance, as well as tumor diagnosis, and prognosis. MiR-1236 is also implicated in epithelial-mesenchymal transition (EMT), which is a significant indicator of the metastatic process. Moreover, miR-1236 itself is regulated by several newly discovered long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs). Current review aimed to summarize and discuss different dimensions of miR-1236 involvement in the fundamental cellular and molecular mechanisms of tumor progressions. We believe that miR-1236 may serve as a non-invasive diagnostic marker and potential therapeutic target for cancer.

Circ_TNFRSF21 promotes cSCC metastasis and M2 macrophage polarization via miR-214-3p/CHI3L1

BACKGROUND

Cutaneous squamous cell carcinoma (cSCC) is a highly invasive disease with the potential to metastasize and cause fatality. Therefore, it is crucial to understand the mechanism behind cSCC in order to devise effective strategies to combat this disease.

OBJECTIVE

We investigated the function of circ_TNFRSF21/miR-214-3p/CHI3L1 axis in cSCC.

METHODS

The features of circ_TNFRSF21 was characterized using Sanger sequencing, and RNase R/actinomycin D treatment. Genes and M1/M2 markers levels were assessed by qRT-PCR and IHC. The proliferation, migration, and invasion of cells were evaluated by CCK-8, colony formation, EdU incorporation, and transwell assays. Tumor growth and metastasis in vivo were evaluated by nude mouse xenograft model. Interactions of circ_TNFRSF21/miR-214-3p and miR-214-3p/CHI3L1 were validated by RNA immunoprecipitation and dual luciferase assay.

RESULTS

Circ_TNFRSF21 and CHI3L1 expression were elevated in both human cSCC tissues and cells, whereas miR-214-3p was reduced. Circ_TNFRSF21 silencing or miR-214-3p overexpression suppressed cSCC cell proliferation, migration, invasion, and M2 macrophage polarization. Circ_TNFRSF21 functioned as a sponge for miR-214-3p while miR-214-3p directly targeted CHI3L1. Knockdown of miR-214-3p reversed the effects of circ_TNFRSF21 knockdown on cSCC development, while CHI3L1 upregulation reversed the effects of miR-214-3p overexpression. Furthermore, knockdown of circ_TNFRSF21 inhibited cSCC tumor growth and metastasis in vivo.

CONCLUSION

Circ_TNFRSF21 plays a significant role in cSCC progression by enhancing cell proliferation, migration, invasion, and M2 macrophage polarization through inhibiting miR-214-3p and subsequent disinhibition of CHI3L1. These findings deepen our understanding of the molecular mechanism of cSCC and propose the circ_TNFRSF21/miR-214-3p/CHI3L1 axis as promising diagnosis markers or therapeutic targets for cSCC.

Circ_0068631 sponges miR-139-5p to promote the growth and metastasis of cutaneous squamous cell carcinoma by upregulating HOXB7

BACKGROUND

Circular RNAs (circRNAs) are often dysregulated in cancers and closely related to cancer progression, including cutaneous squamous cell carcinoma (CSCC). However, the role and mechanism of circ_0068631 in CSCC progression have not been reported.

METHODS

The expression of circ_0068631, microRNA-139-5p (miR-139-5p), and homeobox B7 (HOXB7) was measured by real-time quantitative polymerase chain reaction (RT-qPCR). Cell counting kit-8 (CCK-8) assay, 5-ethynyl-2'-deoxyuridine (EdU) assay, and colony formation assay were used to measure cell proliferation. Cell apoptosis was assessed by flow cytometry. Cell migration was detected by transwell assay. The interaction between miR-139-5p and circ_0068631 or HOXB7 was confirmed by dual-luciferase reporter assay. A xenograft tumor model was established to confirm the function of circ_0068631 in vivo.

RESULTS

Circ_0068631 was upregulated in CSCC tissues and cells, and its silencing could inhibit CSCC cell proliferation and metastasis while promoting apoptosis in vitro, as well as restrain CSCC tumor growth in vivo. Circ_0068631 acted as a sponge of miR-139-5p, and miR-139-5p inhibition reversed the repressive effect of circ_0068631 knockdown on CSCC cell progression. Furthermore, HOXB7 was a target of miR-139-5p, and miR-139-5p inhibited the malignant behaviors by downregulating HOXB7 expression in CSCC cells. Further, circ_0068631 sponged miR-139-5p to regulate HOXB7 expression.

CONCLUSION

Circ_0068631 functioned as a novel oncogene in CSCC progression by regulating miR-139-5p/HOXB7 axis, suggesting that circ_0068631 may be a potential target for CSCC treatment.

HIGHLIGHTS

Circ_0068631 was overexpressed in CSCC tissues and cells. Circ_0068631 downregulation suppressed CSCC progression via miR-139-5p. Circ_0068631 regulated HOXB7 via sponging miR-139-5p.

Knockdown of circRNA circEBF1 inhibits cutaneous squamous cell carcinoma progression by regulating the miR-1247-5p/CSF3 axis

BACKGROUND

Cutaneous squamous cell carcinoma (CSCC) is one of the causes of cancer-related death worldwide. Circular RNAs (circRNAs) play a vital role in the pathological process of many malignant tumors. This study aimed to explore the specific role and potential mechanism of circRNA EBF transcription factor 1 (circEBF1) in CSCC.

METHODS

The levels of circEBF1, microRNA-1247-5p (miR-1247-5p) and colony stimulating factor 3 (CSF3) were determined by quantitative real-time PCR and Western blot. Cell proliferation was assessed by colony formation assay. Cell migration, invasion and apoptosis were evaluated by Transwell, wound healing, flow cytometry and Western blot assays. Cellular glycolysis, including glucose consumption, lactate production, and ATP level, was detected by commercial kits. The binding relationship between miR-1247-5p and circEBF1 or CSF3 was verified by dual-luciferase reporter assay, RNA immunoprecipitation (RIP) assay and RNA pull-down assay. Xenograft experiment was conducted to analyze tumor growth in vivo.

RESULTS

circEBF1 and CSF3 were up-regulated, while miR-1247-5p was down-regulated in CSCC tissues and cells. Interference of circEBF1 hindered the proliferation, migration, invasion, and glycolysis of CSCC cells and promoted apoptosis. In addition, circEBF1 sponged miR-1247-5p to regulate CSCC cell development. Also, miR-1247-5p suppressed CSCC cell progression by inhibiting CSF3. Moreover, depletion of circEBF1 blocked CSCC tumor growth in vivo.

CONCLUSION

Down-regulation of circEBF1 impeded CSCC progression by regulating the miR-1247-5p/CSF3 pathway, suggesting that circEBF1 might be a promising therapeutic target for CSCC.

Non-coding RNAs in skin cancers:Biological roles and molecular mechanisms

Cutaneous malignancies, including basal cell carcinoma, cutaneous squamous cell carcinoma, and cutaneous melanoma, are common human tumors. The incidence of cutaneous malignancies is increasing worldwide, and the leading cause of death is malignant invasion and metastasis. The molecular biology of oncogenes has drawn researchers’ attention because of the potential for targeted therapies. Noncoding RNAs, including microRNAs, long noncoding RNAs, and circular RNAs, have been studied extensively in recent years. This review summarizes the aspects of noncoding RNAs related to the metastasis mechanism of skin malignancies. Continuous research may facilitate the identification of new therapeutic targets and help elucidate the mechanism of tumor metastasis, thus providing new opportunities to improve the survival rate of patients with skin malignancies.

Non-Melanoma Skin Cancer: A Genetic Update and Future Perspectives

Simple Summary

Non-melanoma skin cancer (NMSC) is the main type of cancer in the Caucasian population, and the number of cases continues to rise. Research mostly focuses on clinical characteristics analysis, but genetic features are crucial to malignancies’ establishment and advance. We aim to explore the genetic basics of skin cancer, surrounding microenvironment interactions, and regulation mechanisms to provide a broader perspective for new therapies’ development.

Abstract

Skin cancer is one of the main types of cancer worldwide, and non-melanoma skin cancer (NMSC) is the most frequent within this group. Basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) are the most common types. Multifactorial features are well-known for cancer development, and new hallmarks are gaining relevance. Genetics and epigenetic regulation play an essential role in cancer susceptibility and progression, as well as the variety of cells and molecules that interact in the tumor microenvironment. In this review, we provide an update on the genetic features of NMSC, candidate genes, and new therapies, considering diverse perspectives of skin carcinogenesis. The global health situation and the pandemic have been challenging for health care systems, especially in the diagnosis and treatment of patients with cancer. We provide innovative approaches to overcome the difficulties in the current clinical dynamics.

Circ-LARP1B knockdown restrains the tumorigenicity and enhances radiosensitivity by regulating miR-578/IGF1R axis in hepatocellular carcinoma

INTRODUCTION AND OBJECTIVES

Circular RNA La Ribonucleoprotein 1B (circ-LARP1B) was reported to serve as an oncogene in many types of cancers. Radiotherapy (RT) is an important element of the multimodal treatment concept in malignancies. Here, this work aimed to investigate the role of circ-LARP1B in the tumorigenesis and radiosensitivity of hepatocellular carcinoma (HCC).

PATIENTS OR MATERIALS AND METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot were used to detect the expression of genes and proteins. In vitro experiments were conducted using cell counting Kit-8 (CCK-8), colony formation, EDU, transwell, and tube formation assays, respectively. Dual-luciferase reporter assay was employed to identify the target relationship between miR-578 and circ-LARP1B or IGF1R (insulin-like growth factor 1 receptor). In vivo assay was performed using murine xenograft model.

RESULTS

Circ-LARP1B was highly expressed in HCC tissues and cells, and high expression of circ-LARP1B was closely associated with poor prognosis. Functional experiments demonstrated that circ-LARP1B silencing impaired cell proliferation, invasion, angiogenesis and reduced radioresistance in vitro. Mechanistically, circ-LARP1B could competitively bind with miR-578 to relieve the repression of miR-578 on the expression of its target gene IGF1R. Further rescue assay confirmed that miR-578 inhibition reversed the inhibitory effects of circ-LARP1B knockdown on HCC cell malignant phenotypes and radioresistance. Moreover, miR-578 overexpression restrained tumorigenicity and enhanced radiosensitivity in HCC cells, which were attenuated by IGF1R up-regulation. Besides that, circ-LARP1B knockdown impeded tumor growth and enhanced irradiation sensitivity in HCC in vivo.

CONCLUSIONS

Circ-LARP1B knockdown restrained HCC tumorigenicity and enhanced radiosensitivity by regulating miR-578/IGF1R axis, providing a new target for the treatment of HCC.

Identification of potentially functional circular RNAs hsa_circ_0070934 and hsa_circ_0004315 as prognostic factors of hepatocellular carcinoma by integrated bioinformatics analysis

Hepatocellular carcinoma (HCC) is one of the most prevalent cancers worldwide, which has a high mortality rate and poor treatment outcomes with yet unknown molecular basis. It seems that gene expression plays a pivotal role in the pathogenesis of the disease. Circular RNAs (circRNAs) can interact with microRNAs (miRNAs) to regulate gene expression in various malignancies by acting as competitive endogenous RNAs (ceRNAs). However, the potential pathogenesis roles of the ceRNA network among circRNA/miRNA/mRNA in HCC are unclear. In this study, first, the HCC circRNA expression data were obtained from three Gene Expression Omnibus microarray datasets (GSE164803, GSE94508, GSE97332), and the differentially expressed circRNAs (DECs) were identified using R limma package. Also, the liver hepatocellular carcinoma (LIHC) miRNA and mRNA sequence data were retrieved from TCGA and differentially expressed miRNAs (DEMIs) and mRNAs (DEGs) were determined using the R DESeq2 package. Second, CSCD website was used to uncover the binding sites of miRNAs on DECs. The DECs' potential target miRNAs were revealed by conducting an intersection between predicted miRNAs from CSCD and downregulated DEMIs. Third, candidate genes were uncovered by intersecting targeted genes predicted by miRWalk and targetscan online tools with upregulated DEGs. The ceRNA network was then built using the Cytoscape software. The functional enrichment and the overall survival time of these potential targeted genes were analyzed, and a PPI network was constructed in the STRING database. Network visualization was performed by Cytoscape, and ten hub genes were detected using the CytoHubba plugin tool. Four DECs (hsa_circ_0000520, hsa_circ_0008616, hsa_circ_0070934, hsa_circ_0004315) were obtained and six miRNAs (hsa-miR-542-5p, hsa-miR-326, hsa-miR-511-5p, hsa-miR-195-5p, hsa-miR-214-3p, and hsa-miR-424-5p) which are regulated by the above DECs were identified. Then 543 overlapped genes regulated by six miRNAs mentioned above were predicted. Functional enrichment analysis showed that these genes are mostly associated with regulatory pathways in cancer. Ten hub genes (TTK, AURKB, KIF20A, KIF23, CEP55, CDC6, DTL, NCAPG, CENPF, PLK4) have been screened from the PPI network of the 204 survival-related genes. KIF20A, NCAPG, TTK, PLK4, and CDC6 were selected for the highest significance p-values. At the end, a circRNA-miRNA-mRNA regulatory axis was established for five final selected hub genes. This study implies the potential pathogenesis of the obtained network and proposes that the two DECs (has_circ_0070934 and has_circ_0004315) may be important prognostic markers for HCC.

Circ_0001821 contributes to the development of cutaneous squamous cell carcinoma by regulating miR-148a-3p/EGFR axis and activating PI3K/Akt pathway

Background: Circular RNAs (circRNAs) are implicated in diverse human cancers. However, the effects of circRNAs on cutaneous squamous cell carcinoma (CSCC) are barely known. we focused on the function of circ_0001821 in CSCC. Methods: QRT-PCR assay was performed for the expression of circ_0001821, miR-148a-3p and epidermal growth factor receptor (EGFR). Cell Counting Kit-8 (CCK-8) assay and colony formation assay were conducted to evaluate cell viability and colony formation ability. Flow cytometry analysis was adopted to analyze cell cycle and apoptosis. Transwell assay was employed to detect cell motility. Dual-luciferase reporter assay, RIP assay and RNA pull-down assay were utilized to verify the interaction between miR-148a-3p and circ_0001821 or EGFR. Western blot assay was conducted for protein levels. Murine xenograft model assay was used to explore the function of circ_0001821 in vivo. Results: Circ_0001821 level was increased in CSCC tissues and cells. Circ_0001821 knockdown restrained cell viability, colony formation, cell cycle process and metastasis and facilitated cell apoptosis in vitro and restrained tumor growth in vivo. For mechanism analysis, circ_0001821 directly targeted miR-148a-3p to elevate EGFR expression. Downregulation of miR-148a-3p weakened the impacts of circ_0001821 deficiency on CSCC malignant phenotypes. Moreover, miR-148a-3p overexpression inhibited the malignant phenotypes of CSCC cells, with EGFR elevation abrogated the effects. In addition, circ_0001821 knockdown blocked the activation of PI3K/Akt pathway. Conclusion: Circ_0001821 functioned as a tumor promotor in CSCC via regulating miR-148a-3p/EGFR axis and PI3K/Akt pathway.

Circular RNA circ-LARP1B contributes to cutaneous squamous cell carcinoma progression by targeting microRNA-515-5p/TPX2 microtubule nucleation factor axis

Circular RNAs (circRNAs) have shown pivotal regulatory roles in tumorigenesis and progression. Our purpose was to analyze the role of circRNA La ribonucleoprotein 1B (circ-LARP1B; hsa_circ_0070934) in cutaneous squamous cell carcinoma (CSCC) progression and its associated mechanism. Cell viability, colony formation ability, migration, and invasion were analyzed by 3-(4, 5-dimethylthiazol-2-yl)-2, 5 diphenyltetrazolium bromide (MTT) assay, colony formation assay, wound healing assay, and transwell invasion assay. Flow cytometry was performed to analyze cell apoptosis and cell cycle progression. Cell glycolytic metabolism was analyzed using Glucose Uptake Colorimetric Assay kit, Lactate Assay Kit II, and ATP colorimetric Assay kit. Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were performed to verify the interaction between microRNA-515-5p (miR-515-5p) and circ-LARP1B or TPX2 microtubule nucleation factor (TPX2). Circ-LARP1B expression was up-regulated in CSCC tissues and cell lines. Circ-LARP1B knockdown suppressed cell viability, colony formation ability, migration, invasion, cell cycle progression, and glycolysis and triggered cell apoptosis in CSCC cells. miR-515-5p was a direct target of circ-LARP1B in CSCC cells, and circ-LARP1B silencing-mediated anti-tumor effects were largely counteracted by miR-515-5p knockdown. miR-515-5p directly interacted with the 3' untranslated region (3'UTR) of TPX2. TPX2 overexpression largely overturned miR-515-5p-mediated anti-tumor effects in CSCC cells. Circ-LARP1B could up-regulate TPX2 expression by sponging miR-515-5p in CSCC cells. Circ-LARP1B knockdown suppressed tumor growth in vivo. In conclusion, circ-LARP1B contributed to CSCC progression by targeting miR-515-5p/TPX2 axis. The circ-LARP1B/miR-515-5p/TPX2 axis might provide novel therapeutic targets for CSCC patients.

Noncoding RNAs: emerging players in skin cancers pathogenesis

Skin malignancies form in tissues of the skin and are the most frequent cancers in the world, with an increasing incidence and a steady fatality rate. They are classified as melanoma or nonmelanoma cancers, which include basal cell carcinoma and squamous cell carcinoma. Noncoding RNA transcripts have received increased attention after the thorough analysis of the human genome revealed that most of the genomic components are not encoded to protein. MicroRNAs, long noncoding RNAs, and circular RNAs are some of the well-studied types of these noncoding regions. The alteration in any of these members' expression is associated intrinsically with human cancers, including skin malignancies, due to their critical functions in cell processes for normal development. As a result, investigating the noncoding component of the transcriptome opens up the possibility of discovering new therapeutic and diagnostic targets. This review discusses current studies on the involvement of microRNAs, long noncoding RNAs, and circular RNAs in the pathogenesis of human skin cancers.

CircRNA_103948 inhibits autophagy in colorectal cancer in a ceRNA manner

Circular RNA (circRNA) is implicated in many types of cancer; however, the expression and role of circRNAs in colorectal cancer (CRC) remains poorly understood. In this study, a circRNA microarray assay was performed to detect abnormally expressed circRNAs in CRC, and tissue arrays were used to determine the prognosis for CRC patients. Cell counting kit-8, clone formation, wound healing, and transwell assays were used to evaluate cell functions in vitro, and a mouse subcutaneous tumor model was designed for in vivo analysis. Autophagy was observed using confocal laser scanning and transmission electron microscopy. The expression of circRNA, miRNA, and mRNA was detected using qPCR; western blot, RNA pull-down assay, RNA immunoprecipitation, and dual luciferase assessment were applied for mechanistic studies. We found that circRNA_103948 expression is upregulated in CRC tissues, compared with adjacent normal tissues, and associated with poor prognosis. Knockdown of circRNA_103948 suppressed CRC both in vitro and in vivo. Mechanistically, circRNA_103948 could directly bind to miR-1236-3p and relieve suppression of the target TPT1. Furthermore, circRNA_103948 inhibited autophagy of CRC cells. Taken together, circRNA_103948 knockdown inhibited CRC cell growth by targeting miR-1236-3p/TPT1 axis-mediated autophagy. Thus, the circRNA_103948/miR-1236-3p/TPT1 axis affects CRC progression via modulation of autophagy.

Non-coding RNA dysregulation in skin cancers

Skin cancers are the most common cancers worldwide. They can be classified in melanoma and non-melanoma skin cancer (NMSC), the latter includes squamous cell carcinoma (SCC), basal cell carcinoma (BCC) and merkel cell carcinoma (MCC). In recent years, the crucial role of non-coding RNAs (ncRNAs) in skin cancer pathogenesis has become increasingly evident. NcRNAs are functional RNA molecules that lack any protein-coding activity. These ncRNAs are classified based on their length: small, medium-size, and long ncRNAs. Among the most studied ncRNAs there are microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNA (circRNAs). ncRNAs have the ability to regulate gene expression at transcriptional and post-transcriptional levels and are involved in skin cancer cell proliferation, angiogenesis, invasion, and metastasis. Many ncRNAs exhibit tissue- or cell-specific expression while others have been correlated to tumor staging, drug resistance, and prognosis. For these reasons, ncRNAs have both a diagnostic and prognostic significance in skin cancers. Our review summarizes the functional role of ncRNAs in skin cancers and their potential clinical application as biomarkers.

Identification of potential immune-related circRNA-miRNA-mRNA regulatory network in cutaneous squamous cell carcinoma

Circulating RNAs (circRNAs) are involved in tumor development and progression by participating in immune regulation. Nevertheless, the circRNAs expression profiles and their roles on the immunomodulatory effects in cutaneous squamous cell carcinoma (cSCC) have rarely been studied. In our study, we identified the differentially expressed circRNAs (DEcircRNAs), miRNAs (DEmiRNAs), mRNAs (DEmRNAs) in cSCC and established the circRNA competing endogenous RNAs (ceRNAs) network. Subsequently, the hub differentially expressed immune-related genes were identified and validated by immunochemistry as well as the GO and KEGG pathway analysis were performed. 54 differentially expressed circRNAs were identified and hub differentially expressed immune-related genes were identified and they were mostly associated with immune response in the progression of cSCC. Our results indicated that the potential immune-related circRNA-miRNA-mRNA network may assist in understanding the molecular mechanisms underlying the carcinogenesis and progression in cSCC. Moreover, the immune-related genes may provide an insight into the pathogenesis, molecular biomarkers, and potential therapeutic targets for cSCC patients.

Oh, the Mutations You'll Acquire! A Systematic Overview of Cutaneous Squamous Cell Carcinoma

Nearly two million cases of cutaneous squamous cell carcinoma (cSCC) are diagnosed every year in the United States alone. cSCC is notable for both its prevalence and its propensity for invasion and metastasis. For many patients, surgery is curative. However, patients experiencing immunosuppression or recurrent, advanced, and metastatic disease still face limited therapeutic options and significant mortality. cSCC forms after decades of sun exposure and possesses the highest known mutation rate of all cancers. This mutational burden complicates efforts to identify the primary factors driving cSCC initiation and progression, which in turn hinders the development of targeted therapeutics. In this review, we summarize the mutations and alterations that have been observed in patients’ cSCC tumors, affecting signaling pathways, transcriptional regulators, and the microenvironment. We also highlight novel therapeutic opportunities in development and clinical trials.

The Role of Circular RNAs in Keratinocyte Carcinomas

Keratinocyte carcinomas (KC) include basal cell carcinomas (BCC) and cutaneous squamous cell carcinomas (cSCC) and represents the most common cancer in Europe and North America. Both entities are characterized by a very high mutational burden, mainly UV signature mutations. Predominately mutated genes in BCC belong to the sonic hedgehog pathway, whereas, in cSCC, TP53, CDKN2A, NOTCH1/2 and others are most frequently mutated. In addition, the dysregulation of factors associated with epithelial to mesenchymal transition (EMT) was shown in invasive cSCC. The expression of factors associated with tumorigenesis can be controlled in several ways and include non-coding RNA molecules, such as micro RNAs (miRNA) long noncoding RNAs (lncRNA) and circular RNAs (circRNA). To update findings on circRNA in KC, we reviewed 13 papers published since 2016, identified in a PubMed search. In both BCC and cSCC, numerous circRNAs were identified that were differently expressed compared to healthy skin. Some of them were shown to target miRNAs that are also dysregulated in KC. Moreover, some studies confirmed the biological functions of individual circRNAs involved in cancer development. Thus, circRNAs may be used as biomarkers of disease and disease progression and represent potential targets of new therapeutic approaches for KC.

Hsa_circ_0008234 facilitates proliferation of cutaneous squamous cell carcinoma through targeting miR-127-5p to regulate ADCY7

Cutaneous squamous cell carcinoma (cSCC) is the second most common skin malignant tumor with 25-50% of 5-year survival. There exist urgent needs for the identification of novel biomarkers for the diagnostic and therapeutic strategies of cSCC. The differentially expressed circRNAs in cSCC tissues and non-lesional skin tissues were obtained through analyzing the circular RNAs (circRNAs) microarray dataset GSE74758. The expression pattern of the indicated circRNAs in cSCC tissues was confirmed by qRT-PCR. FISH analysis was used to detect the location of hsa_circ_0008234 in cells. RIP experiment was used to detect the interaction between hsa_circ_0008234 and miR-127-5p. CCK-8 analysis and colony formation assay were used to detect the proliferation of cSCC cells. qRT-PCR and western blot were adopted to detect the expression of ACDY7. Three differential expressed circRNAs were obtained from the microarray data (GSE74758), and hsa_circ_0008234 was confirmed to be highly expressed in cSCC tissues by qRT-PCR. Hsa_circ_0008234 was mainly located in cytoplasm and stable in cSCC cells. RIP experiment revealed that hsa_circ_0008234 directly interacts with miR-127-5p in cSCC cells. Hsa_circ_0008234 increased the cell viability and colony formation of cSCC cells through acting as the sponge of miR-127-5p. MiR-127-5p inhibited the expression of ADCY7 in cSCC cells through binding the 3'UTR of ADCY7. Hsa_circ_0008234 was positively associated with ADCY7 expression in cSCC tissues. Hsa_circ_0008234 facilitates the proliferation of cSCC through targeting miR-127-5p to regulate ADCY7 expression and has the potential to be a novel therapeutic target for cSCC.

Grape Seed Proanthocyanidins (GSPs) Inhibit the Development of Cutaneous Squamous Cell Carcinoma by Regulating the hsa_circ_0070934/miR-136-5p/PRAF2 Axis

Background

Grape seed proanthocyanidins (GSPs) have been shown to inhibit the progression of many cancers, including cutaneous squamous cell carcinoma (CSCC). Circular RNA (circRNA) is a key regulator for cancer progression. However, it is unclear whether GSPs can mediate the progression of CSCC by regulating circRNA.

Methods

Quantitative real-time PCR was conducted to determine the expression of hsa_circ_0070934, microRNA (miR)-136-5p and prenylated Rab acceptor family 2 (PRAF2). MTT assay and colony formation assay were used to assess cell proliferation. Cell cycle process and apoptosis were detected by flow cytometry, and cell migration and invasion were measured by transwell assay. Western blot analysis was utilized to examine protein expression. In addition, dual-luciferase reporter assay and RIP assay were used to evaluate the interaction between miR-136-5p and hsa_circ_0070934 or PRAF2. Subcutaneous xenograft models were constructed to explore the function of GSPs on CSCC tumor growth in vivo.

Results

GSPs could reduce hsa_circ_0070934 expression and inhibit CSCC cell proliferation, cell cycle process, migration, invasion, while promote apoptosis. Overexpressed hsa_circ_0070934 could reverse the suppressive effect of GSPs on CSCC cell progression. MiR-136-5p could be sponged by hsa_circ_0070934, and its overexpression also abolished the positively regulation of hsa_circ_0070934 on the progression of GSPs-induced CSCC cells. PRAF2 was a target of miR-136-5p, and its expression could be decreased by GSPs and increased by hsa_circ_0070934. The inhibitory effect of miR-136-5p on CSCC cell progression could be reversed by PRAF2 overexpression. Additionally, GSPs also could inhibit CSCC tumor growth in vivo.

Conclusion

Our data showed that GSPs regulated the hsa_circ_0070934/miR-136-5p/PRAF2 axis to restrain CSCC progression.

LINC00894 Enhances the Progression of Breast Cancer by Sponging miR-429 to Regulate ZEB1 Expression

PURPOSE

Long non-coding RNAs (lncRNAs) are known to regulate tumorigenesis. Although breast cancer tissues show a high expression of LINC00894, its specific biological role in breast cancer progression is still unknown. In this study, lncRNA microarray was used to analyze the lncRNA expression in breast cancer tissues, and LINC00894 was selected for further analysis.

MATERIALS AND METHODS

Expression of LINC00894 in 45 pairs of breast cancer tissues and normal tissues obtained from patients with breast cancer was assessed by quantitative reverse transcription-PCR, while proliferation and invasion of breast cancer cells were assessed using a Cell Counting Kit-8 (CCK-8), EdU assay, colony formation experiment, and transwell assays. A dual-luciferase reporter gene assay and bioinformatics analysis were employed to detect potential targets of LINC00894. Additionally, RNA Binding Protein Immunoprecipitation (RIP) and Western blot assays were utilized to clarify its interaction and roles in the regulation of breast cancer progression.

RESULTS

High expression of LINC00894 was observed in breast cancer cells, and its overexpression significantly expedited cell proliferation and invasion. Moreover, LINC00894 positively regulated the expression of ZEB1 by competitively binding to miR-429.

CONCLUSION

Taken together, these results suggest that LINC00894 competitively binds to miR-429 to mediate ZEB1 expression; consequently, it is implicated to play a role in the progression of breast cancer.

Exosomal Circular RNA RNA-seq Profiling and the Carcinogenic Role of Exosomal circ-CYP24A1 in Cutaneous Squamous Cell Carcinoma

Objective: Aberrantly expressed exosomal circular RNAs (circRNAs) have been reported in various human cancers. Nevertheless, it remains elusive in cutaneous squamous cell carcinoma (cSCC). Herein, based on RNA-seq, we systematically uncovered the expression and implication of exosomal circRNAs in cSCC.

Methods: Plasma exosomes derived from cSCC and healthy subjects were characterized by nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM), and western blot. Differentially expressed exosomal circular RNAs (circRNAs) were screened by RNA-seq analysis, which were validated by RT-qPCR. Among them, the biological structure of circ-CYP24A1 was validated by Sanger sequencing and RNase R digestion. Si-circ-CYP24A1 was transfected into exosomes, followed by incubation with A431 and SCL-1 cells. Then, viability, apoptosis, migration, and invasion were evaluated by CCK-8, TUNEL staining and migration assays.

Results: This study identified 25 up- and 76 down-regulated exosomal circRNAs in cSCC than healthy subjects. Among them, circulating circ-CYP24A1 was confirmed to be up-regulated in cSCC. Circ-CYP24A1 had a covalently closed circular structure and was not sensitive to RNase R digestion. After incubation with si-circ-CYP24A1-transfected exosomes, proliferation, migration, and invasion were lowered while apoptosis was enhanced in A431 and SCL-1 cells. Meanwhile, si-circ-CYP24A1-transfected exosomes significantly decreased the expression of downstream targets CDS2, MAVS, and SOGA in cSCC cells.

Conclusion: Collectively, our study identified that targeting exosomal circ-CYP24A1 could suppress cSCC progression by weakening tumor malignant behaviors, which might provide a promising therapeutic target and non-invasive diagnostic biomarker for cSCC.