Circular RNAs Could Encode Unique Proteins and Affect Cancer Pathways

CircRNAs constitute a novel class of RNA, generally considered as non-coding RNAs; nonetheless, their coding potential has been under scrutiny. In this work, we systematically explored the predicted proteins of more than 160,000 circRNAs detected by exome capture RNA-sequencing and collected in the MiOncoCirc pan-cancer compendium, including normal and cancer samples from different types of tissues. For the functional evaluation, we compared their primary structure and domain composition with those derived from the same linear mRNAs. Among the 4362 circRNAs potentially encoding proteins with a unique primary structure and 1179 encoding proteins with a novel domain composition, 183 were differentially expressed in cancer. In particular, eight were associated with prognosis in acute myeloid leukemia. The functional classification of the dysregulated circRNA-encoded polypeptides showed an enrichment in the heme and cancer signaling, DNA-binding, and phosphorylation processes, and disclosed the roles of some circRNA-based effectors in cancer

Protein Kinase C at the Crossroad of Mutations, Cancer, Targeted Therapy and Immune Response

The frequent PKC dysregulations observed in many tumors have made these enzymes natural targets for anticancer applications. Nevertheless, this considerable interest in the development of PKC modulators has not led to the expected therapeutic benefits, likely due to the complex biological activities regulated by PKC isoenzymes, often playing ambiguous and protective functions, further driven by the occurrence of mutations. The structure, regulation and functions of PKCs have been extensively covered in other publications. Herein, we focused on PKC alterations mostly associated with complete functional loss. We also addressed the modest yet encouraging results obtained targeting PKC in selected malignancies and the more frequent negative clinical outcomes. The reported observations advocate the need for more selective molecules and a better understanding of the involved pathways. Furthermore, we underlined the most relevant immune mechanisms controlled by PKC isoforms potentially impacting the immune checkpoint inhibitor blockade-mediated immune recovery. We believe that a comprehensive examination of the molecular features of the tumor microenvironment might improve clinical outcomes by tailoring PKC modulation. This approach can be further supported by the identification of potential response biomarkers, which may indicate patients who may benefit from the manipulation of distinctive PKC isoforms

Inhibition of the lncRNA Coded within Transglutaminase 2 Gene Impacts Several Relevant Networks in MCF-7 Breast Cancer Cells

Long non-coding RNAs are nucleotide molecules that regulate transcription in numerous cellular processes and are related to the occurrence of many diseases, including cancer. In this regard, we recently discovered a polyadenylated long non-coding RNA (named TG2-lncRNA) encoded within the first intron of the Transglutaminase type 2 gene (TGM2), which is related to tumour proliferation in human cancer cell lines. To better characterize this new biological player, we investigated the effects of its suppression in MCF-7 breast cancer cells, using siRNA treatment and RNA-sequencing. In this way, we found modifications in several networks associated to biological functions relevant for tumorigenesis (apoptosis, chronic inflammation, angiogenesis, immunomodulation, cell mobility, and epithelial-mesenchymal transition) that were originally attributed only to Transglutaminase type 2 protein but that could be regulated also by TG2-lncRNA. Moreover, our experiments strongly suggest the ability of TG2-lncRNA to directly interact with important transcription factors, such as RXRα and TP53, paving the way for several regulatory loops that can potentially influence the phenotypic behaviour of MCF-7 cells. These considerations imply the need to further investigate the relative relevance of the TG2 protein itself and/or other gene products as key regulators in the organization of breast cancer program

State-of-the-art in transposable element modulation affected by drugs in malignant prostatic cancer cells

Over recent years, the investigation of transposable elements (TEs) has granted researchers a deeper comprehension of their characteristics and functions, particularly regarding their significance in the mechanisms contributing to cancer development. This manuscript focuses on prostate carcinoma cell lines and offers a comprehensive review intended to scrutinize the associations and interactions between TEs and genes, as well as their response to treatment using various chemical drugs, emphasizing their involvement in cancer progression. We assembled a compendium of articles retrieved from the PubMed database to construct networks demonstrating correlations with genes and pharmaceuticals. In doing so, we linked the transposition of certain TE types to the expression of specific transcripts directly implicated in carcinogenesis. Additionally, we underline that treatment employing different drugs revealed unique patterns of TE reactivation. Our hypothesis gathers the current understanding and guides research toward evidence-based investigations, emphasizing the association between antiviral drugs, chemotherapy, and the reduced expression of TEs in patients affected by prostate cancer

Prelude therapeutics: Transglutaminase type 2 inhibitors target Kv10.1 channels in triple negative MDA-MB-231 breast cancer cells

Type 2 Transglutaminase (TG2) in addition to being endowed with transmidating activity by which it regulates several extra- and intracellular functions, can also act as membrane G protein. In this context, it has been reported that TG2 is involved in the regulation of potassium current in several models, which however express different types of potassium channels. In this study we have analyzed the intracellular effects of TG2 using specific inhibitors, which could affect not only the catalytic activity, but also the GTPase function, modifying conformational states. We applied this approach using patch-clamp technique coupled to the administration of the specific inibitor NC9 in breast cancer MDA-MB-231 single-cell, because they are rappresentative of triple negative phenotype, a tumour still difficult to treat. We applied a current-voltage protocol ranging from -90 to +70 mV (20 mV step) to control cells (n=14) and NC9 treated cells (n=6). The TG2 inhibitor led to significant decrease in the membrane current. The treatment of MDA-MB-231 cells with AA9, another TG2 inhibitor, was more effective than NC9 decreasing by 90.1±3.3% the +70 mV current-voltage (two way ANOVA, P<0.001). Since the main ion involved in the genesis of the membrane current is the K+ ion, we attempted to identify the possible K+-channel target of TG2. The literature suggests that the most abundant K+-channel in cancer cells is Kv10.1. In order to demonstrate that it is present in MDA-MB-231 cells, we repeated the patch clamp experiments by treating the cells with its specific inhibitor 4-amino-pyridine. This treatment led to reduction of the membrane current equal to 88.4±3.5% comparable to that obtained with AA9. These results suggest an involvement of TG2 in the regulation of the Kv10.1 channels, and this effect is of particular interest because this type of channel, generally expressed in excitable cells, is of exclusive use in MDA-MB-231 cells, in which other potassium channels result mutated or altered. This aspect makes it an important therapeutic target for targeted therapy. The consequences of this alteration in the membrane current remain to be investigated, since it is associated in non-neuronal models with secretion processes, as in the case of pancreatic beta cells, in which TG2 appears to direct the traffic of vesicles for insulin secretion. The analysis of the secretome of these tumor cells will contribute to define other players involved and orchestrated by TG2

Inverse Impact of Cancer Drugs on Circular and Linear RNAs in Breast Cancer Cell Lines

Altered expression of circular RNAs (circRNAs) has previously been investigated in breast cancer. However, little is known about the effects of drugs on their regulation and relationship with the cognate linear transcript (linRNA). We analyzed the dysregulation of both 12 cancer-related circRNAs and their linRNAs in two breast cancer cell lines undergoing various treatments. We selected 14 well-known anticancer agents affecting different cellular pathways and examined their impact. Upon drug exposure circRNA/linRNA expression ratios increased, as a result of the downregulation of linRNA and upregulation of circRNA within the same gene. In this study, we highlighted the relevance of identifying the drug-regulated circ/linRNAs according to their oncogenic or anticancer role. Interestingly, VRK1 and MAN1A2 were increased by several drugs in both cell lines. However, they display opposite effects, circ/linVRK1 favors apoptosis whereas circ/linMAN1A2 stimulates cell migration, and only XL765 did not alter the ratio of other dangerous circ/linRNAs in MCF-7. In MDA-MB-231 cells, AMG511 and GSK1070916 decreased circGFRA1, as a good response to drugs. Furthermore, some circRNAs might be associated with specific mutated pathways, such as the PI3K/AKT in MCF-7 cells with circ/linHIPK3 correlating to cancer progression and drug-resistance, or NHEJ DNA repair pathway in TP-53 mutated MDA-MB-231 cells

Drug repurposing and transposable elements: a new promising strategy to fight prostate cancer

New sequencing technologies have enhanced the study of transposable elements (TEs), pivotal in organism evolution and implicated in diseases like cancer. Reactivated TEs, notably LINE-1 retrotransposons, correlate with cancer development, including prostate cancer (PCa). Our group explored the effects of anti-retroviral drugs on TE expression in PCa cells (PC-3). Transcriptome analysis post-treatment revealed significant gene alterations, particularly in inflammation-related pathways, alongside modulation of TE expression. This suggests anti-retrovirals could complement standard PCa therapies, although further validation and functional analysis are warranted