Sumoylation as an Emerging Target in Therapeutics against Cancer

Post-Translational Modifications in Multiple Myeloma: Mechanisms of Drug Resistance and Therapeutic Opportunities

Multiple myeloma (MM) remains an incurable hematologic malignancy due to the inevitable development of drug resistance, particularly in relapsed or refractory cases. Post-translational modifications (PTMs), including phosphorylation, ubiquitination, acetylation, and glycosylation, play pivotal roles in regulating protein function, stability, and interactions, thereby influencing MM pathogenesis and therapeutic resistance. This review comprehensively explores the mechanisms by which dysregulated PTMs contribute to drug resistance in MM, focusing on their impact on key signaling pathways, metabolic reprogramming, and the tumor microenvironment. We highlight how PTMs modulate drug uptake, alter drug targets, and regulate cell survival signals, ultimately promoting resistance to PIs, IMiDs, and other therapeutic agents. Furthermore, we discuss emerging therapeutic strategies targeting PTM-related pathways, which offer promising avenues for overcoming resistance to treatment. By integrating preclinical and clinical insights, this review underscores the potential of PTM-targeted therapies to enhance treatment efficacy and improve patient outcomes in MM.

Elevated UBC9 expression and its oncogenic role in colorectal cancer progression and chemoresistance

Colorectal cancer (CRC) is a highly prevalent and fatal malignancy, with incidence and mortality rates rising globally. While elevated UBC9 expression has been implicated in various cancers, its specific role in CRC remains poorly understood. This study aims to investigate the expression levels, prognostic significance, and functional roles of UBC9 in CRC. We assessed the expression and prognostic value of UBC9 mRNA and protein in colorectal cancer separately using multiple databases and immunohistochemical techniques. Additionally, in vitro functional assays and in vivo zebrafish tumor models were employed to elucidate the role of UBC9 in CRC cell proliferation, migration, invasion, and chemoresistance. UBC9 expression was significantly upregulated in CRC tissues. Elevated UBC9 levels were associated with poor prognosis in chemotherapy-treated CRC patients. Gene Set Enrichment Analysis revealed that pathways related to MYC targets, DNA repair, and oxidative stress response were enriched in groups with high UBC9 expression. Immune profiling indicated reduced infiltration of CD4+ memory-activated T cells and NK cells in tumors with elevated UBC9 levels. Functional assays demonstrated that UBC9 knockdown inhibited CRC cell proliferation, migration, and invasion, and sensitized cells to oxaliplatin, which was further validated using zebrafish xenograft models. UBC9 is crucial for CRC progression, genomic instability, and chemoresistance. It represents a potential prognostic biomarker and therapeutic target, particularly for enhancing chemotherapy efficacy in CRC patients.

USP34 regulates PIN1-cGAS-STING axis-dependent ferroptosis in cervical cancer via SUMOylation

BACKGROUND

Cervical cancer is a prevalent form of cancer in women, and the inhibition of ferroptosis has been shown to promote the progression of cervical cancer tumours. This study aimed to investigate the role of PIN1 in regulating ferroptosis in cervical cancer, focusing on its ability to modulate the cGAS-STING pathway and the potential involvement of USP34 as an upstream regulator of PIN1.

METHODS

PIN1-overexpressing and PIN1-knockdown cell lines were constructed. In addition to activating p-STING via PIN1 knockdown and inhibiting p-STING via PIN1 overexpression, cell activity was evaluated via CCK8, EdU, transwell and flow cytometry assays. The expression of USP34, PIN1, cGAS, p-STING, and STING was analysed through qRT-PCR and immunofluorescence. Western blot analysis was used to detect the regulatory effects of USP34, PIN1, cGAS, p-STING, and STING, as well as SUMOylation. Ferroptosis was detected by ROS immunofluorescence, the mitochondrial membrane potential, and mitochondrial electron microscopy. Furthermore, PIN1-knockdown cells were used to construct xenograft tumours in BALB/c male nude mice, and the relevant verification experiments were performed in vivo.

RESULTS

PIN1 can increase the proliferation and invasion of cervical cancer cells by significantly inhibiting ferroptosis. The mechanism by which PIN1 promotes cancer is inhibition of the cGAS-STING pathway. Additionally, we found that USP34 could increase the expression of PIN1 via SUMOylation in cervical cancer cells.

CONCLUSION

This study confirmed that USP34 could upregulate PIN1 expression and SUMOylation, thereby inhibiting ferroptosis by suppressing the cGAS-STING pathway and in turn promoting the progression of cervical cancer.

SENP7 inhibits glioblastoma metastasis and invasion by dissociating SUMO2/3 binding to specific target proteins

Background

The poor surgical efficacy and recurrence of glioblastoma (GBM) are due to its lack of visible infiltrative features. Our bioinformatics study suggests that low expression of small ubiquitin-like modifier (SUMO)-specific protease 7 (SENP7) indicates poor prognosis in GBM.

Objectives

This study investigated the effect of SENP7 expression on the invasion, migration, and proliferation of GBM cells and aims to identify the SUMO target proteins affected by SENP7.

Methods

SENP7 expression was analyzed in eight GBM tumor samples and four GBM cell lines, comparing them to normal brain tissue. The effect of SENP7 overexpression on GBM LN229 cell migration, invasion, and proliferation was examined through in vitro assays. Furthermore, four SUMO target proteins involved in tumor invasion and proliferation (CDK6, matrix metalloproteinase-9 [MMP9], AKT, and HIF-1α) were studied to explore SENP7's molecular mechanism.

Results

SENP7 expression was significantly lower in GBM tumors compared to normal tissue. SENP7 overexpression in LN229 cells inhibited migration and invasion without affecting proliferation. Overexpression reduced the levels of MMP9, AKT, and HIF-1α, but not CDK6. Immunohistochemical analysis showed decreased MMP9 and CD31 levels, suggesting reduced tumor invasion and angiogenesis. However, SENP7 overexpression did not affect tumor growth in vivo.

Conclusions

SENP7 inhibits GBM invasion by dissociating proteins associated with tumor invasion from SUMO2/3, providing a potential target for future GBM therapies.

The prognosis, chemotherapy and immunotherapy efficacy of the SUMOylation pathway signature and the role of UBA2 in lung adenocarcinoma

Lung adenocarcinoma (LUAD) is one of the most common malignant tumors worldwide. Small Ubiquitin-like Modifier (SUMO)-ylation plays a crucial role in tumorigenesis. However, the SUMOylation pathway landscape and its clinical implications in LUAD remain unclear. Here, we analyzed genes involved in the SUMOylation pathway in LUAD and constructed a SUMOylation pathway signature (SUMOPS) using the LASSO-Cox regression model, validated in independent cohorts. Our analysis revealed significant dysregulation of SUMOylation-related genes in LUAD, comprising of favorable or unfavorable prognostic factors. The SUMOPS model was associated with established molecular and histological subtypes of LUAD, highlighting its clinical relevance. The SUMOPS stratified LUAD patients into SUMOPS-high and SUMOPS-low subtypes with distinct survival outcomes and adjuvant chemotherapy responses. The SUMOPS-low subtype showed favorable responses to adjuvant chemotherapy. The correlations between SUMOPS scores and immune cell infiltration suggested that patients with the SUMOPS-high subtype exhibited favorable immune profiles for immune checkpoint inhibitor (ICI) treatment. Additionally, we identified UBA2 as a key SUMOylation-related gene with an increased expression and a poor prognosis in LUAD. Cell function experiment confirmed the role of UBA2 in promoting LUAD cell proliferation, invasion, and migration. These findings provide valuable insights into the SUMOylation pathway and its prognostic implications in LUAD, paving the way for personalized treatment strategies and the development of novel therapeutic targets.

Increased Small Ubiquitin-like Modifier-Activating Enzyme SAE1 Promotes Hepatocellular Carcinoma by Enhancing mTOR SUMOylation

SUMOylation, one of the most important posttranslational modifications of proteins, plays an essential role in various biological processes; however, enzymes that control SUMOylation in hepatocellular carcinoma (HCC) are still unclear. Comprehensive exploration of the expression and clinical significance of SUMO enzymes in HCC would be of great value. Here, we obtained the gene expression profile of each small ubiquitin-like modifier (SUMO) protein and the corresponding clinical information from The Cancer Genome Atlas. We found that all SUMO enzymes were significantly increased in HCC tissues compared with that in adjacent nontumorous tissues. We identified a 6-gene prognostic signature, including SAE1, PIAS2, PIAS3, SENP3, SENP5, and UBC9, that could effectively predict the overall survival in patients with HCC. Specifically, SAE1 was the most valuable prognostic indicator. In 282 clinical samples, we found that SAE1 was closely related to the clinicopathologic parameters and prognosis of patients with HCC. In vitro and in vivo studies showed that SAE1 knockdown inhibits the proliferation, migration, and invasion of HCC cells. Mechanistically, we confirmed that SAE1 plays a role in driving HCC progression, which is largely dependent on the SUMOylation of mTOR signaling. In conclusion, our study revealed that the expression of SUMO enzymes, especially SAE1, is highly associated with HCC development and acts as a promising prognostic predictor.

PIAS1 Alleviates Hepatic Ischemia-Reperfusion Injury in Mice through a Mechanism Involving NFATc1 SUMOylation

Recently, attentions have come to the alleviatory effect of protein inhibitor of activated STAT1 (PIAS1) in hepatic ischemia-reperfusion injury (HIRI), but the underlying molecular mechanistic actions remain largely unknown, which were illustrated in the present study. Microarray-based analysis predicted a possible regulatory mechanism involving the PIAS1/NFATc1/HDAC1/IRF-1/p38 MAPK signaling axis in HIRI. Then, growth dynamics of hypoxia/reoxygenation- (H/R-) exposed hepatocytes and liver injury of HIRI-like mice were delineated after the alteration of the PIAS1 expression. We validated that PIAS1 downregulation occurred in H/R-exposed hepatocytes and HIRI-like mice, while the expression of NFATc1, HDAC1, and IRF-1 and phosphorylation levels of p38 were increased. PIAS1 inactivated p38 MAPK signaling by inhibiting HDAC1-mediated IRF-1 through NFATc1 SUMOylation, thereby repressing the inflammatory response and apoptosis of hepatocytes in vitro, and alleviated liver injury in vivo. Collectively, the NFATc1/HDAC1/IRF-1/p38 MAPK signaling axis is highlighted as a promising therapeutic target for potentiating hepatoprotective effects of PIAS1 against HIRI.

Ginkgolic acid improves bleomycin-induced pulmonary fibrosis by inhibiting SMAD4 SUMOylation

Idiopathic pulmonary fibrosis (IPF) is a refractory chronic respiratory disease with progressively exacerbating symptoms and a high mortality rate. There are currently only two effective drugs for IPF; thus, there is an urgent need to develop new therapeutics. Previous experiments have shown that ginkgolic acid (GA), as a SUMO-1 inhibitor, exerted an inhibitory effect on cardiac fibrosis induced by myocardial infarction. Regarding the pathogenesis of PF, previous studies have concluded that small ubiquitin-like modifier (SUMO) polypeptides bind multiple target proteins and participate in fibrosis of multiple organs, including PF. In this study, we found altered expression of SUMO family members in lung tissues from IPF patients. GA mediated the reduced expression of SUMO1/2/3 and the overexpression of SENP1 in a PF mouse model, which improved PF phenotypes. At the same time, the protective effect of GA on PF was also confirmed in the SENP1-KO transgenic mice model. Subsequent experiments showed that SUMOylation of SMAD4 was involved in PF. It was inhibited by TGF-β1, but GA could reverse the effects of TGF-β1. SENP1 also inhibited the SUMOylation of SMAD4 and then participated in epithelial-mesenchymal transition (EMT) downstream of TGF-β1. We also found that SENP1 regulation of SMAD4 SUMOylation affected reactive oxygen species (ROS) production during TGF-β1-induced EMT and that GA prevented this oxidative stress through SENP1. Therefore, GA may inhibit the SUMOylation of SMAD4 through SENP1 and participate in TGF-β1-mediated pulmonary EMT, all of which reduce the degree of PF. This study provided potential novel targets and a new alternative for the future clinical testing in PF.

Ubiquitination regulation of aerobic glycolysis in cancer

Aerobic glycolysis, or the Warburg effect, is regarded as a critical part of metabolic reprogramming and plays a crucial role in the occurrence and development of tumours. Ubiquitination and deubiquitination, essential post-translational modifications, have attracted increasing attention with regards to the regulation of metabolic reprogramming in cancer. However, the mechanism of ubiquitination in glycolysis remains unclear. In this review, we discuss the roles of ubiquitination and deubiquitination in regulating glycolysis, and their involvement in regulating important signalling pathways, enzymes, and transcription factors. Focusing on potential mechanisms may provide novel strategies for cancer treatment.

Nanocarrier-Based Drug Delivery for Melanoma Therapeutics

Melanoma, as a tumor cell derived from melanocyte transformation, has the characteristics of malignant proliferation, high metastasis, rapid recurrence, and a low survival rate. Traditional therapy has many shortcomings, including drug side effects and poor patient compliance, and so on. Therefore, the development of an effective treatment is necessary. Currently, nanotechnologies are a promising oncology treatment strategy because of their ability to effectively deliver drugs and other bioactive molecules to targeted tissues with low toxicity, thereby improving the clinical efficacy of cancer therapy. In this review, the application of nanotechnology in the treatment of melanoma is reviewed and discussed. First, the pathogenesis and molecular targets of melanoma are elucidated, and the current clinical treatment strategies and deficiencies of melanoma are then introduced. Following this, we discuss the main features of developing efficient nanosystems and introduce the latest reports in the literature on nanoparticles for the treatment of melanoma. Subsequently, we review and discuss the application of nanoparticles in chemotherapeutic agents, immunotherapy, mRNA vaccines, and photothermal therapy, as well as the potential of nanotechnology in the early diagnosis of melanoma.

The subgroup of 2'-hydroxy-flavonoids: Molecular diversity, mechanism of action, and anticancer properties

Flavonoids are abundant in nature, structurally very diversified and largely investigated. However, the subgroup of 2'-hydroxyflavonoids is much less known and not frequently studied. The present review identifies the major naturally-occurring and synthetic 2'-hydroxyflavonoid derivatives and discusses their structural characteristics and biological properties, with a focus on anticancer activities. The pharmacological properties of 2'-hydroxyflavone (2'-HF) and 2'-hydroxyflavanone (2'-HFa) are detailed. Upon binding to the Ral-interacting protein Rlip implicated in the transport of glutathione conjugates, 2'-HFa inhibits tumor cell proliferation and restrict tumor growth, in particular in breast cancer models. Among the synthetic derivatives, the characteristics of the anticancer product 2D08 (2',3',4'-trihydroxy flavone) are detailed to shed light on the molecular mechanism of action of this compound, as a regulator of protein SUMOylation. Inhibition of protein SUMOylation by 2D08 blocks cancer cell migration and invasion, and the compound greatly enhances the anticancer effects of conventional cytotoxic drugs like etoposide. The structural role of the 2'-hydroxyl group on the phenyl C-ring of the flavonoid is discussed, notably the capacity to engage intramolecular H-bonding interactions with the O1 atom on the B-ring of the chromone unit (or the oxygen of a 3-OH group when it is presents). The 2'-hydroxyl group of flavonoid appears as a regulator of the conformational freedom between the bicyclic A-B unit and the appended phenyl C-ring, favoring the planarity of the molecule. It is an essential group accounting for the biological properties of 2'-HF, 2'-HFa and structurally related compounds. This review shed light on 2'-hydroxyflavonoids to encourage their use and chemical development.