KCTD15 Protein Expression in Peripheral Blood and Acute Myeloid Leukemia

Structural studies of KCTD1 and its disease-causing mutant P20S provide insights into the protein function and misfunction

Members of the KCTD protein family play key roles in fundamental physio-pathological processes including cancer, neurodevelopmental/neuropsychiatric, and genetic diseases. Here, we report the crystal structure of the KCTD1 P20S mutant, which causes the scalp-ear-nipple syndrome, and molecular dynamics (MD) data on the wild-type protein. Surprisingly, the structure unravels that the N-terminal region, which precedes the BTB domain (preBTB) and bears the disease-associated mutation, adopts a folded polyproline II (PPII) state. The KCTD1 pentamer is characterized by an intricate architecture in which the different subunits mutually exchange domains to generate a closed domain swapping motif. Indeed, the BTB of each chain makes peculiar contacts with the preBTB and the C-terminal domain (CTD) of an adjacent chain. The BTB-preBTB interaction consists of a PPII-PPII recognition motif whereas the BTB-CTD contacts are mediated by an unusual (+/-) helix discontinuous association. The inspection of the protein structure, along with the data emerged from the MD simulations, provides an explanation of the pathogenicity of the P20S mutation and unravels the role of the BTB-preBTB interaction in the insurgence of the disease. Finally, the presence of potassium bound to the central cavity of the CTD pentameric assembly provides insights into the role of KCTD1 in metal homeostasis.

A telomere-related gene risk model for predicting prognosis and treatment response in acute myeloid leukemia

Acute myeloid leukemia (AML) is a prevalent hematological malignancy among adults. Recent studies suggest that the length of telomeres could significantly affect both the risk of developing AML and the overall survival (OS). Despite the limited focus on the prognostic value of telomere-related genes (TRGs) in AML, our study aims at addressing this gap by compiling a list of TRGs from TelNet, as well as collecting clinical information and TRGs expression data through the Gene Expression Omnibus (GEO) database. The GSE37642 dataset, sourced from GEO and based on the GPL96 platform, was divided into training and validation sets at a 6:4 ratio. Additionally, the GSE71014 dataset (based on the GPL10558 platform), GSE12417 dataset (based on the GPL96 and GPL570 platforms), and another portion of the GSE37642 dataset (based on the GPL570 platform) were designated as external testing sets. Univariate Cox regression analysis identified 96 TRGs significantly associated with OS. Subsequent Lasso-Cox stepwise regression analysis pinpointed eight TRGs (MCPH1, SLC25A6, STK19, PSAT1, KCTD15, DNMT3B, PSMD5, and TAF2) exhibiting robust predictive potential for patient survival. Both univariate and multivariate survival analyses unveiled TRG risk scores and age as independent prognostic variables. To refine the accuracy of survival prognosis, we developed both a nomogram integrating clinical parameters and a predictive risk score model based on TRGs. In subsequent investigations, associations were emphasized not solely regarding the TRG risk score and immune infiltration patterns but also concerning the response to immune-checkpoint inhibitor (ICI) therapy. In summary, the establishment of a telomere-associated genetic risk model offers a valuable tool for prognosticating AML outcomes, thereby facilitating informed treatment decisions.

KCTD Proteins Have Redundant Functions in Controlling Cellular Growth

We explored the functional redundancy of three structurally related KCTD (Potassium Channel Tetramerization Domain) proteins, KCTD2, KCTD5, and KCTD17, by progressively knocking them out in HEK 293 cells using CRISPR/Cas9 genome editing. After validating the knockout, we assessed the effects of progressive knockout on cell growth and gene expression. We noted that the progressive effects of knockout of KCTD isoforms on cell growth were most pervasive when all three isoforms were deleted, suggesting some functions were conserved between them. This was also reflected in progressive changes in gene expression. Our previous work indicated that Gβ1 was involved in the transcriptional control of gene expression, so we compared the gene expression patterns between GNB1 and KCTD KO. Knockout of GNB1 led to numerous changes in the expression levels of other G protein subunit genes, while knockout of KCTD isoforms had the opposite effect, presumably because of their role in regulating levels of Gβ1. Our work demonstrates a unique relationship between KCTD proteins and Gβ1 and a global role for this subfamily of KCTD proteins in maintaining the ability of cells to survive and proliferate.

KCTD15 Is Overexpressed in her2+ Positive Breast Cancer Patients and Its Silencing Attenuates Proliferation in SKBR3 CELL LINE

Studies carried out in the last decade have demonstrated that the members of the KCTD protein family play active roles in carcinogenesis. Very recently, it has been reported that KCTD15, a protein typically associated with other physio-pathological processes, is involved in medulloblastoma and leukemia. Starting with some preliminary indications that emerged from the analysis of online databases that suggested a possible overexpression of KCTD15 in breast cancer, in this study, we evaluated the expression levels of the protein in breast cancer cell lines and in patients and the effects of its silencing in the HER2+ cell model. The analysis of the KCTD15 levels indicates a significant overexpression of the protein in Luminal A and Luminal B breast cancer patients as well as in the related cell lines. The greatest level of over-expression of the protein was found in HER2+ patients and in the related SKBR3 cell line model system. The effects of KCTD15 silencing in terms of cell proliferation, cell cycle, and sensitivity to doxorubicin were evaluated in the SKBR3 cell line. Notably, the KCTD15 silencing in SKBR3 cells by CRISPR/CAS9 technology significantly attenuates their proliferation and cell cycle progression. Finally, we demonstrated that KCT15 silencing also sensitized SKBR3 cells to the cytotoxic agent doxorubicin, suggesting a possible role of the protein in anti HER2+ therapeutic strategies. Our results highlight a new possible player in HER2 breast cancer carcinogenesis, paving the way for its use in breast cancer diagnosis and therapy.

KCTD15 deregulation is associated with alterations of the NF-κB signaling in both pathological and physiological model systems

Like other KCTD proteins, KCTD15 is involved in important albeit distinct biological processes as cancer, neural crest formation, and obesity. Here, we characterized the role of KCTD15 in different physiological/pathological states to gain insights into its diversified function(s). The silencing of KCTD15 in MLL-rearranged leukemia models induced attenuation of the NF-κB pathway associated with a downregulation of pIKK-β and pIKB-α. Conversely, the activation of peripheral blood T cells upon PMA/ionomycin stimulation remarkably upregulated KCTD15 and, simultaneously, pIKK-β and pIKB-α. Moreover, a significant upregulation of KCTD15 was also observed in CD34 hematopoietic stem/progenitor cells where the NF-κB pathway is physiologically activated. The association between KCTD15 upregulation and increased NF-κB signaling was confirmed by luciferase assay as well as KCTD15 and IKK-β proximity ligation and immunoprecipitation experiments. The observed upregulation of IKK-β by KCTD15 provides a novel and intriguing interpretative key for understanding the protein function in a wide class of physiological/pathological conditions ranging from neuronal development to cancer and obesity/diabetes.

The emerging role of the KCTD proteins in cancer

The human family of Potassium (K+) Channel Tetramerization Domain (KCTD) proteins counts 25 members, and a significant number of them are still only partially characterized. While some of the KCTDs have been linked to neurological disorders or obesity, a growing tally of KCTDs are being associated with cancer hallmarks or involved in the modulation of specific oncogenic pathways. Indeed, the potential relevance of the variegate KCTD family in cancer warrants an updated picture of the current knowledge and highlights the need for further research on KCTD members as either putative therapeutic targets, or diagnostic/prognostic markers. Homology between family members, capability to participate in ubiquitination and degradation of different protein targets, ability to heterodimerize between members, role played in the main signalling pathways involved in development and cancer, are all factors that need to be considered in the search for new key players in tumorigenesis. In this review we summarize the recent published evidence on KCTD members' involvement in cancer. Furthermore, by integrating this information with data extrapolated from public databases that suggest new potential associations with cancers, we hypothesize that the number of KCTD family members involved in tumorigenesis (either as positive or negative modulator) may be bigger than so far demonstrated. Video abstract.

Long non‑coding RNA NEAT1 regulates glioma cell proliferation and apoptosis by competitively binding to microRNA‑324‑5p and upregulating KCTD20 expression

Previous studies have demonstrated that long non‑coding RNAs (lncRNAs) serve a key role in the development and progression of several types of cancer, including glioma. The lncRNA nuclear paraspeckle assembly transcript 1 (NEAT1) contributes to cancer growth through its effects on cell proliferation, migration, invasion and drug resistance. However, the exact regulatory mechanisms via which NEAT1 acts in glioma are unclear. In the present study, the expression levels and function of NEAT1 in glioma tissues and cell lines were examined in vitro and in vivo. By reverse transcription‑quantitative PCR and fluorescence in situ hybridization analysis, NEAT1 expression was upregulated in glioma tissues compared with in adjacent normal brain tissues, and elevated NEAT1 levels were associated with poor prognosis. Cell Counting Kit‑8, colony formation, ethynyldeoxyuridine, flow cytometry and western blotting assays were performed to detect the effects of NEAT1 on cell biological behavior. Knockdown of NEAT1 in glioma cell lines was associated with cell cycle arrest at the G₀/G₁ phase, decreased proliferation and elevated apoptosis in vitro, and resulted in reduced tumor growth and increased survival in a mouse xenograft model of glioma. Using bioinformatics analysis, RNA immunoprecipitation experiments and luciferase reporter assays, it was demonstrated that NEAT1 may competitively bind to microRNA (miR)‑324‑5p, thus blocking its interaction with target mRNAs. Potassium channel tetramerization protein domain containing 20 (KCTD20) was identified as a specific miR‑324‑5p target. Accordingly, the inhibition of NEAT1 resulted in the downregulation of KCTD20 through competitive binding with miR‑324‑5p, decreased cell proliferation and increased apoptosis. Concomitant NEAT1 knockdown and inhibition of miR‑324‑5p partially reversed the effects of NEAT1 knockdown on cell proliferation and apoptosis, and further regulated KCTD20 expression. Collectively, the present findings demonstrated that NEAT1 acted as a competing endogenous RNA for miR‑324‑5p, and identified the NEAT1/miR‑324‑5p/KCTD20 axis as a novel regulatory axis and a potential therapeutic target for human glioma.