Related Experiment Video
Updated: Aug 12, 2026
Utilizing Murine Inducible Telomerase Alleles in the Studies of Tissue Degeneration/Regeneration and Cancer
Published on: April 13, 2015
Hemangiosarcomas, medulloblastomas, and other tumors in Ink4c/p53-null mice
Frederique Zindy1, Lisa M Nilsson, Luc Nguyen
1Department of Genetics and Tumor Cell Biology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA.
Abstract:
Ink4 proteins inhibit the enzymatic activities of cyclin D-dependent kinases, thereby governing transcriptional programs that depend on the activities of the retinoblastoma protein and other retinoblastoma family members (p107 and p130). Mice lacking Ink4c and p53 spontaneously develop a broad spectrum of neoplasms, usually presenting with multiple tumors of different histological types and dying of cancer by 6 months of age. Whereas thymic lymphomas or pituitary tumors predominate in mice lacking p53 or Ink4c, respectively, animals lacking both genes develop many vascular tumors and also present with medulloblastomas not observed in the parental strains. Unlike p53, loss of the Arf tumor suppressor did not contribute to the appearance of vascular or cerebellar tumors. Vascular tumors ranged in severity from angiomas to hemangiosarcomas, some of which could be transplanted into immunocompromised mice. Intriguingly, loss of Ink4c but maintenance of at least one Ink4d allele was required for formation of medulloblastomas in p53-null mice. In situ hybridization revealed that, in newborn mice, Ink4c is detected in the pia mater and in an adjacent layer of rapidly dividing cells within the cerebellar external granule layer (EGL), whereas Ink4d is primarily expressed in Purkinje neurons. Because the pia mater and Purkinje cells sandwich the cerebellar EGL from which medulloblastomas are presumed to arise, Ink4 proteins might function in a cell-autonomous manner in governing neuronal cell cycle exit as well as in a non-cell-autonomous manner in controlling the production of diffusible mitogens and chemokines that influence postnatal development of the cerebellar EGL.
Insights
Mice lacking Ink4c and p53 develop various cancers. Loss of Ink4c is crucial for medulloblastoma formation in p53-null mice, suggesting dual roles in tumor suppression.
Area of Science:
- Molecular Biology
- Oncology
- Developmental Neuroscience
Background:
- Ink4 proteins (Ink4c, Ink4d) regulate cyclin D-dependent kinases, controlling cell cycle progression via retinoblastoma protein family interactions.
- Ink4c and p53 tumor suppressor proteins are critical in preventing neoplasia.
- Combined loss of Ink4c and p53 in mice leads to diverse, aggressive tumors, including vascular neoplasms and medulloblastomas.
Purpose of the Study:
- To investigate the specific roles of Ink4c and Ink4d in tumor development, particularly medulloblastomas, in the context of p53 deficiency.
- To elucidate the cellular and molecular mechanisms underlying Ink4 protein function in cerebellar development and tumorigenesis.
Main Methods:
- Generation and analysis of genetically engineered mouse models lacking Ink4c and/or p53.
- Histopathological examination of tumors developed in these mouse models.
- In situ hybridization to determine the expression patterns of Ink4c and Ink4d in the developing cerebellum.
Main Results:
- Mice lacking both Ink4c and p53 developed a wide array of tumors, including vascular tumors (angiomas to hemangiosarcomas) and medulloblastomas.
- Medulloblastoma formation in p53-null mice required the loss of Ink4c, while Ink4d expression was localized to Purkinje neurons.
- Ink4c expression was detected in the pia mater and external granule layer (EGL) of the newborn cerebellum, regions implicated in medulloblastoma origin.
Conclusions:
- Ink4c plays a critical role in suppressing medulloblastoma formation in a p53-null background.
- Ink4 proteins may exert tumor suppressive functions through both cell-autonomous (governing neuronal cell cycle exit) and non-cell-autonomous mechanisms (influencing cerebellar microenvironment).
- These findings highlight the complex interplay between Ink4 proteins and p53 in preventing diverse cancers and underscore Ink4c's specific role in cerebellar tumorigenesis.
More Related Videos
Related Concept Videos
02:23Abnormal Proliferation
01:05Cancer-Critical Genes II: Tumor Suppressor Genes
When the function of certain critical genes, especially those involved in cell cycle regulation and cell growth signaling cascades, gets disrupted, it upsets the cell cycle progression. Such cells with unchecked cell cycles start proliferating uncontrollably and eventually develop into tumors.
Such genes that act...