Epigenetic Regulation of KPC1 Ubiquitin Ligase Affects the NF-κB Pathway in Melanoma

Abstract

Purpose Abnormal activation of the NF-κB pathway induces a more aggressive phenotype of cutaneous melanoma. Understanding the mechanisms involved in melanoma NF-κB activation may identify novel targets for this pathway. KPC1, an E3 ubiquitin ligase, is a regulator of NF-κB pathway. The objective of this study was to investigate the mechanisms regulating KPC1 expression and its clinical impact in melanoma. Experimental Design The clinical impact of KPC1 expression and its epigenetic regulation were assessed in large cohorts of clinically well-annotated melanoma tissues (tissue micro-arrays; n=137, JWCI cohort; n=40) and The Cancer Genome Atlas database (TCGA cohort, n=370). Using melanoma cell lines, we investigated the functional interactions between KPC1 and NF-κB, and the epigenetic regulations of KPC1, including DNA methylation and microRNA expression. Results We verified that KPC1 suppresses melanoma proliferation by processing NF-κB1 p105 into p50, thereby modulating NF-κB-target gene expression. Concordantly, KPC1 expression was down-regulated in AJCC stage IV melanoma compared to early stages (stage I/II p=0.013, stage III p=0.004), and low KPC1 expression was significantly associated with poor overall survival in stage IV melanoma (n=137, Hazard Ratio 1.810, p=0.006). Furthermore, our data showed that high miR-155-5p expression, which is controlled by DNA methylation at its promoter region (TCGA; Pearson’s r −0.455, p<0.001), is significantly associated with KPC1 down-regulation (JWCI; p=0.028, TCGA; p=0.003). Conclusions This study revealed novel epigenetic regulation of KPC1 associated with NF-κB pathway activation, promoting metastatic melanoma progression. These findings suggest the potential utility of KPC1 and its epigenetic regulation as theranostic targets.

Apoptosis induced by 9,11‑dehydroergosterol peroxide from Ganoderma�Lucidum mycelium in human malignant melanoma cells is Mcl‑1 dependent

“…Incorrect regulation of NF-κB has been linked to cancer, inflammatory and autoimmune diseases. Studies showed that novel epigenetic regulation of KPC1 associated with NF-κB pathway activation, promoting metastatic melanoma progression ( 24 ). These results suggest that it is possible for the steroid 9(11)-DHEP affect melanoma progression via its potential immunosuppressive effect by inhibiting the NF-κB pathway.…”

The Epigenomic Landscape of Pituitary Adenomas Reveals Specific Alterations and Differentiates Among Acromegaly, Cushing's Disease and Endocrine-Inactive Subtypes

“…RNA isolation from FFPE was performed as previously described (19). Briefly, deparaffinization was performed using standard xylene and ethanol rinse, and then digested by proteinase K. RNA was extracted using RNA-Solv Reagent (Omega Bio-Tek) with chloroform, followed by overnight precipitation in isopropanol and the addition of Pellet Paint NF (Novagen).…”

Downregulation of the Ubiquitin-E3 Ligase RNF123 Promotes Upregulation of the NF-κB1 Target SerpinE1 in Aggressive Glioblastoma Tumors

“…The ubiquitin-proteasome system (UPS) plays critical functions to maintain cellular homeostasis. As such the UPS controls the turnover of vital proteins that function in diverse processes such as the cell cycle, DNA-damage repair, cell metabolism, and cell stress [8][9][10][11]. The UPS controls a myriad of cell signaling pathways involved in the cell's inflammatory response, growth, migration, invasion, and homeostasis.…”

“…NF-κB1 (p105) and NF-κB2 (p100) are normally processed and activated into p50 and p52, respectively, by the proteasome system [16]. NF-κB1, or p105, is ubiquitinated by the ubiquitin-E3 ligase KIP1 ubiquitination-promoting complex subunit 1 (KPC1, also called RNF123 for ring finger protein 123) [9]. Ubiquitinated NF-κB1 is processed in the proteasome, which results in the formation and accumulation of p50 in different tumor types [9].…”

“…NF-κB1, or p105, is ubiquitinated by the ubiquitin-E3 ligase KIP1 ubiquitination-promoting complex subunit 1 (KPC1, also called RNF123 for ring finger protein 123) [9]. Ubiquitinated NF-κB1 is processed in the proteasome, which results in the formation and accumulation of p50 in different tumor types [9]. However, studies have reported that RNF123 also modulates the expression of p27 (CDKN1B) in fibroblasts and astrocytes in the spinal cord [17,18].…”