Mutation of SPINOPHILIN (PPP1R9B) found in human tumors promotes the tumorigenic and stemness properties of cells.
Rationale: SPINOPHILIN (SPN, PPP1R9B) is an important tumor suppressor involved in the progression and malignancy of different tumors depending on its association with protein phosphatase 1 (PP1) and the ability of the PP1-SPN holoenzyme to dephosphorylate retinoblastoma (pRB). Methods: We performed a mutational analysis of SPN in human tumors, focusing ... on the region of interaction with PP1 and pRB. We explored the effect of the SPN-A566V mutation in an immortalized non-tumorigenic cell line of epithelial breast tissue, MCF10A, and in two different p53-mutated breast cancer cells lines, T47D and MDA-MB-468. Results: We characterized an oncogenic mutation of SPN found in human tumor samples, SPN-A566V, that affects both the SPN-PP1 interaction and its phosphatase activity. The SPN-A566V mutation does not affect the interaction of the PP1-SPN holoenzyme with pocket proteins pRB, p107 and p130, but it affects its ability to dephosphorylate them during G0/G1 and G1, indicating that the PP1-SPN holoenzyme regulates cell cycle progression. SPN-A566V also promoted stemness, establishing a connection between the cell cycle and stem cell biology via pocket proteins and PP1-SPN regulation. However, only cells with both SPN-A566V and mutant p53 have increased tumorigenic and stemness properties. Conclusions: SPN-A566V, or other equivalent mutations, could be late events that promote tumor progression by increasing the CSC pool and, eventually, the malignant behavior of the tumor.
Mesh Terms:
Animals, Breast Neoplasms, Carcinogenesis, Cell Line, Transformed, Cell Line, Tumor, Female, G1 Phase Cell Cycle Checkpoints, Gene Expression Regulation, Neoplastic, Humans, Mice, Mice, Nude, Microfilament Proteins, Mutation, Neoplastic Stem Cells, Nerve Tissue Proteins, Phosphorylation, Protein Phosphatase 1, Resting Phase, Cell Cycle, Retinoblastoma Protein, Signal Transduction, Tumor Suppressor Protein p53, Xenograft Model Antitumor Assays
Animals, Breast Neoplasms, Carcinogenesis, Cell Line, Transformed, Cell Line, Tumor, Female, G1 Phase Cell Cycle Checkpoints, Gene Expression Regulation, Neoplastic, Humans, Mice, Mice, Nude, Microfilament Proteins, Mutation, Neoplastic Stem Cells, Nerve Tissue Proteins, Phosphorylation, Protein Phosphatase 1, Resting Phase, Cell Cycle, Retinoblastoma Protein, Signal Transduction, Tumor Suppressor Protein p53, Xenograft Model Antitumor Assays
Theranostics
Date: Feb. 05, 2021
PubMed ID: 33537097
View in: Pubmed Google Scholar
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