The role of RNA binding proteins in hepatocellular carcinoma

RNA-binding protein QKI promotes the progression of HCC by interacting with long non-coding RNA EGOT

BACKGROUND

RNA-binding proteins are revealed to play important roles during the progression of hepatocellular carcinoma (HCC). However, the regulatory mechanisms of RNA-binding protein Quaking (QKI) in the expression and role of long non-coding RNAs (lncRNAs) in HCC cells remain not well understood.

METHODS

Cell Counting Kit-8, wound-healing, Transwell and colony-forming assays were performed to evaluate the effects of QKI and lncRNA EGOT on proliferation and migration of HCC cells. Tumor growth of HCC was analyzed using a mouse xenograft model. Immunoprecipitation (RIP) assay was used to investigate the interaction between QKI and EGOT.

RESULTS

The expression of QKI was significantly upregulated in HCC tissues and the higher QKI level was significantly associated with a poorer prognosis. Overexpression of QKI promoted the proliferation, migration, and colony-forming ability of HCC cells in vitro and tumor growth of HCC in vivo. Mechanistically, QKI protein could bind to EGOT RNA and increase its expression. Inhibition of EGOT attenuated the effects of QKI on the malignant phenotypes of HCC cells. In addition, both QKI and EGOT could activate the SAPK/JNK signaling pathway in HCC cells.

CONCLUSIONS

Our findings indicated that QKI exerted promotive effects on the malignant phenotypes of HCC through its interaction with EGOT.

HNRNPL facilitates ferroptosis in hepatocellular carcinoma cells by promoting S100A9 expression

OBJECTIVE

This study probed into the effect of HNRNPL on ferroptosis in hepatocellular carcinoma (HCC) cells and related molecular mechanisms.

METHODS

Expression patterns of HNRNPL, Recombinant S100 Calcium Binding Protein A9 (S100A9) were analyzed in HCC tissues or cells. Following transfection, HCC cell activity was analyzed, followed by detection of levels of ROS, iron content, LPO, MDA, and GSH as well as the expression of ferroptosis-related proteins. For molecular mechanism, RIP, RNA pull-down assay and actinomycin D assay were implemented to verify the binding relationship between HNRNPL and S100A9. Finally, in vivo nude mouse xenograft tumor experiments were performed for further validate the crucial role of HNENPL expression in HCC.

RESULTS

HNRNPL and S100A9 were significantly overexpressed in HCC. sh-HNRNPL treatment led to a significant decrease in cellular activity, GSH content, and expression of GPX4 and SLC7A11, and a significant increase in iron content, LPO level, MDA, ROS content, and expression of ACSL4 and TFR1. In addition, after sh-HNRNPL was combined with oe-S100A9 or Fer-1, a ferroptosis inhibitor, both oe-S100A9 and Fer-1 reversed the promotional effect of sh-HNRNPL on ferroptosis of HCC cells when sh-HNRNPL acted alone. Mechanically, HNRNPL promoted S100A9 mRNA stability and expression through RBP. Furthermore, low expression of HNRNPL in vivo delayed the growth of xenograft tumors and the expression of ferroptosis-related proteins.

CONCLUSION

HNRNPL promotes S100A9 mRNA stability and expression through RBP action, thereby promoting ferroptosis in HCC cells.

RNA-binding proteins in breast cancer: Biological implications and therapeutic opportunities

RNA-binding proteins (RBPs) refer to a class of proteins that participate in alternative splicing, RNA stability, polyadenylation, localization and translation of RNAs, thus regulating gene expression in post-transcriptional manner. Dysregulation of RNA-RBP interaction contributes to various diseases, including cancer. In breast cancer, disorders in RBP expression and function influence the biological characteristics of tumor cells. Targeting RBPs has fostered the development of innovative therapies for breast cancer. However, the RBP-related mechanisms in breast cancer are not completely clear. In this review, we summarize the regulatory mechanisms of RBPs and their signaling crosstalk in breast cancer. Specifically, we emphasize the potential of certain RBPs as prognostic factors due to their effects on proliferation, invasion, apoptosis, and therapy resistance of breast cancer cells. Most importantly, we present a comprehensive overview of the latest RBP-related therapeutic strategies and novel therapeutic targets that have proven to be useful in the treatment of breast cancer.

RNA-binding protein RPS7 promotes hepatocellular carcinoma progression via LOXL2-dependent activation of ITGB1/FAK/SRC signaling

BACKGROUND

Metastasis is one of the leading cause contributes to treatment failure and poor prognosis of hepatocellular carcinoma (HCC) patients. The underlying mechanism of HCC metastasis remains to be determined. Although several RNA binding proteins (RBPs) have been found to participate in tumorigenesis and progression of liver cancer, the role of RBPs in HCC patients with extrahepatic metastases is poorly understood.

METHODS

By performing RNA-seq of primary HCC tissues (including HCC with extrahepatic metastasis and those did not develop metastasis), we identified a set of HCC metastasis-associated RBPs candidates. Among which, ribosomal protein S7 (RPS7) was found to be remarkably increased in HCC tissues and be strongly related to HCC poor survival. Overexpression or CRISPR-Cas9-mediated knockout were applied to investigate the role of RPS7 on the metastasis-associated phenotypes of HCC cells. RNA sequencing, RIP, RNA-pull down, dual luciferase reporter assay, nascent RNA capture assay, and RNA decay and so on, were applied to reveal the underlying mechanism of RPS7 induced HCC metastasis.

RESULTS

Gain- and loss- of function analyses revealed that RPS7 promoted HCC cells adhesion, migration and invasion capabilities, as well as lung metastasis. Mechanistically, we uncovered that lysyl oxidase-like 2 (LOXL2) was a critical downstream target of RPS7. RPS7 could stabilize LOXL2 mRNA by binding to AUUUA motifs in the 3155-3375 region of the 3'UTR of LOXL2 mRNA, thus increased LOXL2 expression via elevating LOXL2 mRNA abundance. Further research revealed that LOXL2 could accelerate focal adhesion formation through maintaining the protein stability of ITGB1 and activating ITGB1-mediated FAK/SRC signaling pathway, and thereby contribute to the pro-metastasis effect of RPS7.

CONCLUSIONS

Taken together, our data reveal a novel function of RPS7 in HCC metastasis, also reveal the critical roles of the RPS7/LOXL2/ITGB1 axis in HCC metastasis and shed new light on the exploration of molecular drugs against HCC.

Unraveling the Role of RNA-Binding Proteins, with a Focus on RPS5, in the Malignant Progression of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) represents a major global health concern, demanding a thorough understanding of its molecular mechanisms for effective therapeutic strategies. RNA-binding proteins (RBPs) play critical roles in post-transcriptional gene regulation, with their dysregulation increasingly recognized as a hallmark of various cancers. However, the specific contributions of RBPs to HCC pathogenesis and prevention remain incompletely understood. In this study, we systematically conducted an examination of the expression profiles and clinical relevance of RBPs in 556 clinical samples from well-established cohorts. Through comprehensive analyses, a subset of RBPs exhibiting significant overexpression in HCC was identified, establishing a noteworthy correlation between their aberrant expression and HCC progression. Furthermore, 40S ribosomal protein S5 (RPS5), a ribosomal protein, emerged as a potential key contributor in HCC progression. Rigorous analyses established a correlation between elevated RPS5 expression and advanced clinicopathological features, suggesting its potential as a prognostic biomarker. Experiments further confirmed the impact of RPS5 on pivotal cellular processes implicated in cancer progression, including cell proliferation and metastasis. Further mechanistic studies unveiled the potential of RPS5 to activate the cell cycle by binding to key molecules involved in the pathway, thereby promoting the malignant progression of HCC. Additionally, our analysis of the etiology behind RPS5 overexpression in HCC posited it as an outcome of transcriptional regulation by the transcription factors Nuclear Respiratory Factor 1 (NRF1) and MYC-associated zinc finger protein (MAZ). In conclusion, our study contributes to the growing evidence elucidating the intricate involvement of RBPs, exemplified by RPS5, in the malignant progression of HCC. The integration of genomic, transcriptomic, and functional analyses provides a comprehensive understanding of the regulatory mechanisms associated with RPS5 in HCC. This comprehensive analysis not only advances our knowledge of the molecular drivers behind HCC but also highlights the potential therapeutic relevance of targeting RBPs and their regulatory network for the development of more effective treatment strategies.

KIAA1429 protects hepatocellular carcinoma cells from ferroptotic cell death with a m6 A-dependent posttranscriptional modification of SLC7A11

N6 -methyladenosine (m6 A) modification represents the most abundant internal methylation of eukaryotic RNAs. KIAA1429 acts as a key component of the m6 A methyltransferase complex, but its function and mechanism in ferroptotic cell death of hepatocellular carcinoma (HCC) are barely defined. We found that KIAA1429 suppression triggered ferroptosis in HCC cells according to increased cell death, iron and MDA levels, C11-BODIPY-positive cells, ROS production and decreased GSH level. Ferroptosis inhibitors ferrostatin-1 (0.5 μM) and liproxstatin-1 (10 μM) blocked KIAA1429 suppression-induced ferroptosis of HCC cells. In addition, overexpressed KIAA1429 notably heightened the activity of cystine/glutamate antiporter (SLC7A11). SLC7A11 up-regulation partially hindered KIAA1429 inhibition-mediated ferroptosis of HCC cells. The regulation SLC7A11 by KIAA1429 was attenuated by global m6 A inhibitor cycloleucine (40 μM). RNA immunoprecipitation confirmed the binding of KIAA1429 to m6 A on SLC7A11 transcript. Additionally, it was proven that KIAA1429 inhibition mitigated HCC growth in subcutaneous xenograft mice through SLC7A11. Altogether, our findings first propose that KIAA1429 protects HCC cells from ferroptosis with a m6 A-dependent post-transcriptional modification of SLC7A11 and offer a novel insight into the dysregulated epi-transcriptomics in the context of HCC.

Deciphering roles of TRIMs as promising targets in hepatocellular carcinoma: current advances and future directions

Tripartite motif (TRIM) family is assigned to RING-finger-containing ligases harboring the largest number of proteins in E3 ubiquitin ligating enzymes. E3 ubiquitin ligases target the specific substrate for proteasomal degradation via the ubiquitin-proteasome system (UPS), which seems to be a more effective and direct strategy for tumor therapy. Recent advances have demonstrated that TRIM genes associate with the occurrence and progression of hepatocellular carcinoma (HCC). TRIMs trigger or inhibit multiple biological activities like proliferation, apoptosis, metastasis, ferroptosis and autophagy in HCC dependent on its highly conserved yet diverse structures. Remarkably, autophagy is another proteolytic pathway for intracellular protein degradation and TRIM proteins may help to delineate the interaction between the two proteolytic systems. In depth research on the precise molecular mechanisms of TRIM family will allow for targeting TRIM in HCC treatment. We also highlight several potential directions warranted further development associated with TRIM family to provide bright insight into its translational values in hepatocellular carcinoma.

RNA-binding proteins in degenerative joint diseases: A systematic review

RNA-binding proteins (RBPs), which are conserved proteins comprising multiple intermediate sequences, can interact with proteins, messenger RNA (mRNA) of coding genes, and non-coding RNAs to perform different biological functions, such as the regulation of mRNA stability, selective polyadenylation, and the management of non-coding microRNA (miRNA) synthesis to affect downstream targets. This article will highlight the functions of RBPs, in degenerative joint diseases (intervertebral disc degeneration [IVDD] and osteoarthritis [OA]). It will reviews the latest advancements on the regulatory mechanism of RBPs in degenerative joint diseases, in order to understand the pathophysiology, early diagnosis and treatment of OA and IVDD from a new perspective.

MiR-22 Deficiency Fosters Hepatocellular Carcinoma Development in Fatty Liver

MiR-22 is mostly considered as a hepatic tumor-suppressor microRNA based on in vitro analyses. Yet, whether miR-22 exerts a tumor-suppressive function in the liver has not been investigated in vivo. Herein, in silico analyses of miR-22 expression were performed in hepatocellular carcinomas from human patient cohorts and different mouse models. Diethylnitrosamine-induced hepatocellular carcinomas were then investigated in lean and diet-induced obese miR-22-deficient mice. The proteome of liver tissues from miR-22-deficient mice prior to hepatocellular carcinoma development was further analyzed to uncover miR-22 regulated factors that impact hepatocarcinogenesis with miR-22 deficiency. MiR-22 downregulation was consistently observed in hepatocellular carcinomas from all human cohorts and mouse models investigated. The time of appearance of the first tumors was decreased and the number of tumoral foci induced by diethylnitrosamine was significantly increased by miR-22-deficiency in vivo, two features which were further drastically exacerbated with diet-induced obesity. At the molecular level, we provide evidence that the loss of miR-22 significantly affects the energetic metabolism and mitochondrial functions of hepatocytes, and the expression of tumor-promoting factors such as thrombospondin-1. Our study demonstrates that miR-22 acts as a hepatic tumor suppressor in vivo by restraining pro-carcinogenic metabolic deregulations through pleiotropic mechanisms and the overexpression of relevant oncogenes.