CENPK

CENPK is a constitutive centromere protein that forms a stoichiometric heterodimeric complex with CENP-H at kinetochores via coiled-coil interactions, contributing to kinetochore assembly (PMID:19381461). Beyond its canonical kinetochore role, CENPK functions as an oncogenic signaling scaffold in multiple cancer types: it physically interacts with XRCC5 (Ku80) to promote proliferation and migration in gastric cancer (PMID:35715658), binds SOX6 to disrupt β-catenin sequestration and activate Wnt signaling in cervical cancer (PMID:35418160), and signals through JAK1/STAT3 in breast cancer where its transcription is driven by CTCF (PMID:41797275). A cancer-associated splice variant lacking exon 8 (CENPK-Δ8) acquires neomorphic interactions with FLNA and FLOT1, linking aberrant splicing to cytoskeletal remodeling and drug-resistant cell migration (PMID:39404386).

1. 2009 Medium

   Establishing that CENPK is not simply a kinetochore-associated protein but forms a defined biochemical subunit — a ~1:1 heterodimer with CENP-H via coiled-coil domains — provided the first structural framework for its kinetochore function.

   Evidence Tandem affinity purification from HEK 293 cells with domain mapping and coiled-coil prediction

   PMID:19381461

   Open questions at the time

   • No crystal or cryo-EM structure of the CENP-H/K heterodimer
   • Functional consequence of disrupting the coiled-coil interaction on kinetochore integrity not tested
   • Stoichiometry validated by single purification method without biophysical confirmation
2. 2017 Low

   The finding that CENPK overexpression stimulates AKT and MDM2 phosphorylation while suppressing p53 phosphorylation in hepatocellular carcinoma cells first suggested that CENPK has oncogenic signaling functions beyond its kinetochore role.

   Evidence Overexpression/knockdown in HCC cell lines with Western blot for phospho-AKT, phospho-MDM2, and phospho-p53

   PMID:29088763

   Open questions at the time

   • No direct biochemical interaction between CENPK and AKT/MDM2/p53 demonstrated
   • Single method (Western blot) in a single lab without epistasis validation
   • Mechanism by which a kinetochore protein engages cytoplasmic kinase cascades undefined
3. 2019 Low

   Demonstration that YAP1 re-expression partially rescues proliferation and EMT defects caused by CENPK knockdown positioned CENPK upstream of YAP1, connecting it to Hippo pathway output in liver cancer.

   Evidence shRNA knockdown with YAP1 rescue in HCC cells; functional assays including wound healing and Transwell

   PMID:30774374

   Open questions at the time

   • No direct CENPK–YAP1 binding shown; pathway link is inferred from rescue
   • Single lab, no independent confirmation
   • Mechanism of CENPK-mediated YAP1 regulation not defined
4. 2021 Low

   Studies in gastric cancer and tongue squamous cell carcinoma broadened CENPK's oncogenic signaling repertoire to include PTEN–PI3K–AKT and JAK/STAT3 pathways, suggesting context-dependent pathway engagement.

   Evidence shRNA knockdown and overexpression in gastric cancer and TSCC cells; Western blot for PI3K, p-AKT, p-GSK3β, PTEN, JAK, and STAT3; xenograft models

   PMID:33658048 PMID:34382342

   Open questions at the time

   • All pathway placements based on Western blot correlations without direct interaction data
   • No mechanism explaining how CENPK regulates these diverse signaling cascades
   • Findings from single labs with no independent replication
5. 2022 Medium

   Identification of XRCC5 (Ku80) as a direct CENPK interactor via Co-IP/MS and functional rescue provided the first biochemically validated non-kinetochore binding partner, linking CENPK to DNA damage response components in gastric cancer.

   Evidence Reciprocal co-immunoprecipitation with LC-MS identification; XRCC5 overexpression rescue of CENPK knockdown phenotypes in gastric cancer cells

   PMID:35715658

   Open questions at the time

   • Domain mapping of CENPK–XRCC5 interaction not performed
   • Whether this interaction occurs at kinetochores, in the nucleoplasm, or both is unknown
   • Functional consequence for DNA repair not directly tested
6. 2022 Medium

   The discovery that ZC3H13 mediates m6A methylation of CENPK mRNA and that CENPK protein binds SOX6 to liberate β-catenin for nuclear translocation revealed both a post-transcriptional regulatory layer and a direct mechanism for Wnt pathway activation in cervical cancer.

   Evidence MeRIP, co-immunoprecipitation, ChIP, luciferase reporter, cycloheximide chase, and cell fractionation in cervical cancer cells

   PMID:35418160

   Open questions at the time

   • Structural basis of CENPK–SOX6 interaction unknown
   • Whether m6A-dependent CENPK regulation operates in non-cancer contexts not tested
   • Single lab; SOX6 interaction not confirmed by orthogonal biophysical methods
7. 2024 Medium

   Discovery that the CENPK-Δ8 splice variant selectively binds FLNA and FLOT1 — interactions absent for wild-type CENPK — revealed that alternative splicing generates neomorphic protein interactions linking CENPK to cytoskeletal organization and drug resistance.

   Evidence Co-IP comparing wild-type and Δ8 splice variant; patient-derived xenografts and 3D organoids from abiraterone-resistant prostate cancer

   PMID:39404386

   Open questions at the time

   • Structural basis for why exon 8 loss exposes FLNA/FLOT1 binding interfaces unknown
   • Whether CENPK-Δ8 retains kinetochore localization and CENP-H binding not tested
   • Prevalence and regulation of this splice variant across cancer types undefined
8. 2024 Low

   Showing that E2F1 directly drives CENPK transcription and that CENPK activates mTOR signaling through GOLPH3, with CENPK silencing sensitizing cells to rapamycin, established a transcription factor–effector–druggable pathway axis in ovarian cancer.

   Evidence ChIP and transcriptional reporter assays for E2F1; CENPK knockdown with mTOR pathway readouts; rapamycin combination experiments

   PMID:38670220

   Open questions at the time

   • Mechanism of CENPK–GOLPH3–mTOR connection not biochemically defined
   • Single lab without independent validation
   • Whether rapamycin sensitization translates in vivo not shown
9. 2026 Medium

   Demonstrating that CTCF directly binds the CENPK promoter and that the resulting CTCF–CENPK–JAK1/STAT3 axis drives tamoxifen resistance established a second transcription factor input and connected CENPK to endocrine therapy failure in breast cancer.

   Evidence ChIP-qPCR, luciferase reporter, knockdown/overexpression rescue, Western blot for phospho-JAK1/STAT3, thermal shift assay, molecular docking

   PMID:41797275

   Open questions at the time

   • Whether CENPK directly binds JAK1 or acts indirectly unknown
   • Relationship between CTCF- and E2F1-driven transcription of CENPK not explored
   • Applicability to tamoxifen resistance in clinical cohorts not validated

• It remains unknown how CENPK mechanistically transitions from its canonical kinetochore role to engagement with diverse cytoplasmic signaling pathways, and whether its oncogenic functions require kinetochore dissociation or represent moonlighting at distinct subcellular compartments.
• No structural model of CENPK in complex with any non-kinetochore partner
• Subcellular localization of CENPK's signaling-active pools not resolved
• Whether CENPK oncogenic functions are kinetochore-dependent or -independent is untested