Impact of posttranslational modifications in pancreatic carcinogenesis and treatments

Serine/threonine-protein kinase D2-mediated phosphorylation of DSG2 threonine 730 promotes esophageal squamous cell carcinoma progression

Desmoglein-2 (DSG2) is a transmembrane glycoprotein belonging to the desmosomal cadherin family, which mediates cell-cell junctions; regulates cell proliferation, migration, and invasion; and promotes tumor development and metastasis. We previously showed serum DSG2 to be a potential biomarker for the diagnosis of esophageal squamous cell carcinoma (ESCC), although the significance and underlying molecular mechanisms were not identified. Here, we found that DSG2 was increased in ESCC tissues compared with adjacent tissues. In addition, we demonstrated that DSG2 promoted ESCC cell migration and invasion. Furthermore, using interactome analysis, we identified serine/threonine-protein kinase D2 (PRKD2) as a novel DSG2 kinase that mediates the phosphorylation of DSG2 at threonine 730 (T730). Functionally, DSG2 promoted ESCC cell migration and invasion dependent on DSG2-T730 phosphorylation. Mechanistically, DSG2 T730 phosphorylation activated EGFR, Src, AKT, and ERK signaling pathways. In addition, DSG2 and PRKD2 were positively correlated with each other, and the overall survival time of ESCC patients with high DSG2 and PRKD2 was shorter than that of patients with low DSG2 and PRKD2 levels. In summary, PRKD2 is a novel DSG2 kinase, and PRKD2-mediated DSG2 T730 phosphorylation promotes ESCC progression. These findings may facilitate the development of future therapeutic agents that target DSG2 and DSG2 phosphorylation. © 2024 The Pathological Society of Great Britain and Ireland.

Modification of lysine-260 2-hydroxyisobutyrylation destabilizes ALDH1A1 expression to regulate bladder cancer progression

ALDH1A1 is one of the classical stem cell markers for bladder cancer. Lysine 2-hydroxyisobutyrylation (Khib) is a newfound modification to modulate the protein expression, and the underlying mechanisms of how ALDH1A1 was regulated by Khib modification in bladder cancer remains unknown. Here, ALDH1A1 showed a decreased K260hib modification, as identified by protein modification omics in bladder cancer. Decreasing ALDH1A1 expression significantly suppressed the proliferation, migration and invasion of bladder cancer cells. Moreover, K260hib modification is responsible for the activity of ALDH1A1 in bladder cancer, which is regulated by HDAC2/3. Higher K260hib modification on ALDH1A1 promotes protein degradation through chaperone-mediated autophagy (CMA), and ALDH1A1 K260hib could sensitize bladder cancer cells to chemotherapeutic drugs. Higher ALDH1A1 expression with a lower K260hib modification indicates a poor prognosis in patients with bladder cancer. Overall, we demonstrated that K260hib of ALDH1A1 can be used as a potential therapeutic target for bladder cancer treatment.

Biological characteristics of pancreatic ductal adenocarcinoma: Initiation to malignancy, intracellular to extracellular

Pancreatic ductal adenocarcinoma (PDAC) is a highly life-threatening tumour with a low early-detection rate, rapid progression and a tendency to develop resistance to chemotherapy. Therefore, understanding the regulatory mechanisms underlying the initiation, development and metastasis of pancreatic cancer is necessary for enhancing therapeutic effectiveness. In this review, we summarised single-gene mutations (including KRAS, CDKN2A, TP53, SMAD4 and some other less prevalent mutations), epigenetic changes (including DNA methylation, histone modifications and RNA interference) and large chromosome alterations (such as copy number variations, chromosome rearrangements and chromothripsis) associated with PDAC. In addition, we discussed variations in signalling pathways that act as intermediate oncogenic factors in PDAC, including PI3K/AKT, MAPK/ERK, Hippo and TGF-β signalling pathways. The focus of this review was to investigate alterations in the microenvironment of PDAC, particularly the role of immunosuppressive cells, cancer-associated fibroblasts, lymphocytes, other para-cancerous cells and tumour extracellular matrix in tumour progression. Peripheral axons innervating the pancreas have been reported to play a crucial role in the development of cancer. In addition, tumour cells can influence the behaviour of neighbouring non-tumour cells by secreting certain factors, both locally and at a distance. In this review, we elucidated the alterations in intracellular molecules and the extracellular environment that occur during the progression of PDAC. Altogether, this review may enhance the understanding of the biological characteristics of PDAC and guide the development of more precise treatment strategies.

USPs in Pancreatic Ductal Adenocarcinoma: A Comprehensive Bioinformatic Analysis of Expression, Prognostic Significance, and Immune Infiltration

Pancreatic ductal adenocarcinoma (PDAC), as an intractable malignancy, still causes an extremely high mortality worldwide. The ubiquitin-specific protease (USP) family constitutes the major part of deubiquitinating enzymes (DUBs) which has been reported to be involved in initiation and progression of various malignancies via the function of deubiquitination. However, the biological function and clinical values of USPs in PDAC have not been comprehensively elucidated. In this study, Gene Expression Profiling Interactive Analysis (GEPIA), Gene Expression Omnibus (GEO) datasets, UALCAN database, and the Human Protein Atlas (HPA) online tool were used to analyze the expression level and the relationship between USP expression and clinicopathological features in PDAC. Survival module of HPA and Kaplan-Meier plotter (KMP) databases was recruited to explore the prognostic value of USPs. Tumor Immune Estimation Resource (TIMER) online tool and KMP databases were utilized to elucidate tumor immune infiltration and immune-related survival of USPs. CBioPortal online tool was used to identify the gene mutation level of USPs in PDAC. Both cBioPortal and LinkedOmics were used to confirm the potential biological functions of USPs in PDAC. Our study showed that USP10, USP14, USP18, USP32, USP33, and USP39 (termed as six-USPs) expressions were significantly elevated in tumor tissues. The high expression of the four USPs (USP10, USP14, USP18, and USP39) indicated a poor prognosis. A significant relationship was indicated between the expression of six-USPs and clinicopathological features. Also, the expression of six-USPs was related to promoter methylation level. Moreover, more than 40% genetic alterations and mutations were discovered in six-USPs. Furthermore, the six-USP expression was correlated with immune infiltration and immune-related prognosis. The functional analysis found that the six-USPs were involved in various biological processes and signaling pathways, such as nucleocytoplasmic transport, choline metabolism in cancer, cell cycle, ErbB signaling pathway, RIG-I-like receptor signaling pathway, TGF-β signaling pathway, and TNF signaling pathway. In conclusion, the results showed that six-USPs are potential prognostic biomarkers and can be recruited as possible therapeutic targets of PDAC.

Dysregulation of SIRT3 SUMOylation Confers AML Chemoresistance via Controlling HES1-Dependent Fatty Acid Oxidation

Sirtuin 3 (SIRT3) deacetylase is a key regulator for chemoresistance in acute myeloid leukemia (AML) cells due to its capability of modulating mitochondrial metabolism and reactive oxygen species (ROS). SIRT3 is de-SUMOylated by SUMO-specific peptidase 1 (SENP1), which enhances its deacetylase activity. Therefore, dysregulation of SIRT3 SUMOylation may lead to fortified chemoresistance in AML. Indeed, SIRT3 de-SUMOylation was induced by chemotherapeutic agents, which in turn, exacerbated resistance against chemotherapies in AML by activating SIRT3 via preventing its proteasome degradation. Furthermore, RNA-seq revealed that expression of a collection of genes was altered by SIRT3 de-SUMOylation including inhibition of transcription factor Hes Family BHLH Transcription Factor 1 (HES1), a downstream substrate of Notch1 signaling pathway, leading to increased fatty acids oxidation (FAO). Moreover, the SENP1 inhibitor momordin-Ic or HES1 overexpression synergized with cytarabine to eradicate AML cells in vitro and in xenograft mouse models. In summary, the current study revealed a novel role of SIRT3 SUMOylation in the regulation of chemoresistance in AML via HES1-dependent FAO and provided a rationale for SIRT3 SUMOylation and FAO targeted interventions to improve chemotherapies in AML.

Pevonedistat Suppresses Pancreatic Cancer Growth via Inactivation of the Neddylation Pathway

Background

The neddylation pathway is aberrantly overactivated in multiple human cancers and has been indicated as an effective target for anticancer therapy in clinical trials. We aimed to study whether the neddylation pathway is upregulated in pancreatic cancer and whether pevonedistat, a first-in-class anticancer agent specifically targeting this pathway, will suppress cancer tumorigenesis and progression.

Methods

We evaluated the expression pattern of neddylation pathway components in 179 pancreatic adenocarcinoma (PAAD) compared with 171 normal tissues from The Cancer Genome Atlas (TCGA) dataset and further assessed PAAD patient prognosis with high neddylation pathway expression via Gene Expression Profiling Interactive Analysis (GEPIA). We then analyzed malignant cancer phenotypes both in vitro and in vivo, as well as intrinsic molecular mechanisms upon pevonedistat treatment.

Results

We found that the neddylation pathway was hyperactivated in pancreatic cancer. Patients with high neddylation pathway expression exhibited worse prognoses. Pevonedistat significantly inhibited the cancer cell cycle, cell growth, and proliferation; increased cell apoptosis; and decreased cancer cell xenografts in a mouse model. Mechanistically, pevonedistat treatment and the siRNA knockdown neddylation pathway were able to remarkably induce the accumulation of Wee1, p27, and p21. Further mechanistic studies revealed that pevonedistat mainly impaired the ubiquitination level and delayed the protein degradation of Wee1, p27, and p21.

Conclusions

Our results showed that pevonedistat targeted the overexpression of the neddylation pathway in pancreatic cancer to induce cell growth suppression by inducing the accumulation of the cell cycle regulators Wee1, p27, and p21, which provides sound evidence for the clinical trial of pevonedistat for pancreatic cancer therapy.

Posttranslational modifications in pathogenesis of PCOS

Polycystic ovary syndrome (PCOS) is a lifelong reproductive, metabolic, and psychiatric disorder that affects 5-18% of women, which is associated with a significantly increased lifetime risk of concomitant diseases, including type 2 diabetes, psychiatric disorders, and gynecological cancers. Posttranslational modifications (PTMs) play an important role in changes in protein function and are necessary to maintain cellular viability and biological processes, thus their maladjustment can lead to disease. Growing evidence suggests the association between PCOS and posttranslational modifications. This article mainly reviews the research status of phosphorylation, methylation, acetylation, and ubiquitination, as well as their roles and molecular mechanisms in the development of PCOS. In addition, we briefly summarize research and clinical trials of PCOS therapy to advance our understanding of agents that can be used to target phosphorylated, methylated, acetylated, and ubiquitinated PTM types. It provides not only ideas for future research on the mechanism of PCOS but also ideas for PCOS treatments with therapeutic potential.