Low SP1 SUMOylation-dependent SNHG17 upregulation promotes drug resistance of gastric cancer through impairing hsa-miR-23b-3p-induced Notch2 inhibition

Long Non-Coding RNAs in Drug Resistance of Gastric Cancer: Complex Mechanisms and Potential Clinical Applications

Gastric cancer (GC) ranks as the third most prevalent malignancy and a leading cause of cancer-related mortality worldwide. However, the majority of patients with GC are diagnosed at an advanced stage, highlighting the urgent need for effective perioperative and postoperative chemotherapy to prevent relapse and metastasis. The current treatment strategies have limited overall efficacy because of intrinsic or acquired drug resistance. Recent evidence suggests that dysregulated long non-coding RNAs (lncRNAs) play a significant role in mediating drug resistance in GC. Therefore, there is an imperative to explore novel molecular mechanisms underlying drug resistance in order to overcome this challenging issue. With advancements in deep transcriptome sequencing technology, lncRNAs-once considered transcriptional noise-have garnered widespread attention as potential regulators of carcinogenesis, including tumor cell proliferation, metastasis, and sensitivity to chemo- or radiotherapy through multiple regulatory mechanisms. In light of these findings, we aim to review the mechanisms by which lncRNAs contribute to drug therapy resistance in GC with the goal of providing new insights and breakthroughs toward overcoming this formidable obstacle.

SNHG17 alters anaerobic glycolysis by resetting phosphorylation modification of PGK1 to foster pro-tumor macrophage formation in pancreatic ductal adenocarcinoma

BACKGROUND

Within the tumor immune microenvironment (TME), tumor-associated macrophages (TAMs) are crucial in modulating polarization states to influence cancer development through metabolic reprogramming. While long non-coding RNAs (lncRNAs) have been shown to play a pivotal role in the progression of various cancers, the underlying mechanisms by which lncRNAs alter M2 polarization through macrophage metabolism remodeling remain unelucidated.

METHODS

RNA sequencing was used to screen for differentially expressed lncRNAs in TAMs and normal tissue-resident macrophages (NTRMs) isolated from pancreatic ductal adenocarcinoma (PDAC) tissues, whilst RT-qPCR and FISH were employed to detect the expression level of SNHG17. Moreover, a series of in vivo and in vitro experiments were conducted to assess the functions of SNHG17 from TAMs in the polarization and glycolysis of M2-like macrophages and in the proliferation and metastasis of pancreatic cancer cells (PCs). Furthermore, Western blotting, RNA pull-down, mass spectrometry, RIP, and dual-luciferase assays were utilized to explore the underlying mechanism through which SNHG17 induces pro-tumor macrophage formation.

RESULTS

SNHG17 was substantially enriched in TAMs and was positively correlated with a worse prognosis in PDAC. Meanwhile, functional assays determined that SNHG17 promoted the malignant progression of PCs by enhancing M2 macrophage polarization and anaerobic glycolysis. Mechanistically, SNHG17 could sponge miR-628-5p to release PGK1 mRNA and concurrently interact with the PGK1 protein, activating the pro-tumorigenic function of PGK1 by enhancing phosphorylation at the T168A site of PGK1 through ERK1/2 recruitment. Lastly, SNHG17 knockdown could reverse the polarization status of macrophages in PDAC.

CONCLUSIONS

The present study illustrated the essential role of SNHG17 and its molecular mechanism in TAMs derived from PDAC, indicating that SNHG17 might be a viable target for PDAC immunotherapy.

Role of non-canonical post-translational modifications in gastrointestinal tumors

Post-translational modifications (PTMs) of proteins contribute to the occurrence and development of tumors. Previous studies have suggested that canonical PTMs such as ubiquitination, glycosylation, and phosphorylation are closely implicated in different aspects of gastrointestinal tumors. Recently, emerging evidence showed that non-canonical PTMs play an essential role in the carcinogenesis, metastasis and treatment of gastrointestinal tumors. Therefore, we summarized recent advances in sumoylation, neddylation, isoprenylation, succinylation and other non-canonical PTMs in gastrointestinal tumors, which comprehensively describe the mechanisms and functions of non-classical PTMs in gastrointestinal tumors. It is anticipated that targeting specific PTMs could benefit the treatment as well as improve the prognosis of gastrointestinal tumors.

The emerging roles of SUMOylation in the tumor microenvironment and therapeutic implications

Tumor initiation, progression, and response to therapies depend to a great extent on interactions between malignant cells and the tumor microenvironment (TME), which denotes the cancerous/non-cancerous cells, cytokines, chemokines, and various other factors around tumors. Cancer cells as well as stroma cells can not only obtain adaption to the TME but also sculpt their microenvironment through a series of signaling pathways. The post-translational modification (PTM) of eukaryotic cells by small ubiquitin-related modifier (SUMO) proteins is now recognized as a key flexible pathway. Proteins involved in tumorigenesis guiding several biological processes including chromatin organization, DNA repair, transcription, protein trafficking, and signal conduction rely on SUMOylation. The purpose of this review is to explore the role that SUMOylation plays in the TME formation and reprogramming, emphasize the importance of targeting SUMOylation to intervene in the TME and discuss the potential of SUMOylation inhibitors (SUMOi) in ameliorating tumor prognosis.