Geminin is required for Hox gene regulation to pattern the developing limb
DEVELOPMENTAL BIOLOGY
Authors: Lewis, Emily M. A.; Sankar, Savita; Tong, Caili; Patterson, Ethan S.; Waller, Laura E.; Gontarz, Paul; Zhang, Bo; Ornitz, David M.; Kroll, Kristen L.
Abstract
Development of the complex structure of the vertebrate limb requires carefully orchestrated interactions between multiple regulatory pathways and proteins. Among these, precise regulation of 5' Hox transcription factor expression is essential for proper limb bud patterning and elaboration of distinct limb skeletal elements. Here, we identified Geminin (Gmnn) as a novel regulator of this process. A conditional model of Gmnn deficiency resulted in loss or severe reduction of forelimb skeletal elements, while both the forelimb autopod and hindlimb were unaffected. 5' Hox gene expression expanded into more proximal and anterior regions of the embryonic forelimb buds in this Gmnn-deficient model. A second conditional model of Gmnn deficiency instead caused a similar but less severe reduction of hindlimb skeletal elements and hindlimb polydactyly, while not affecting the forelimb. An ectopic posterior SHH signaling center was evident in the anterior hindlimb bud of Gmnn-deficient embryos in this model. This center ectopically expressed Hoxd13, the HOXD13 target Shh, and the SHH target Ptch1, while these mutant hindlimb buds also had reduced levels of the cleaved, repressor form of GLI3, a SHH pathway antagonist. Together, this work delineates a new role for Gmnn in modulating Hox expression to pattern the vertebrate limb.
Overexpression of Cell Cycle Progression Inhibitor Geminin is Associated with Tumor Stem-Like Phenotype of Triple-Negative Breast Cancer
JOURNAL OF BREAST CANCER
Authors: Di Bonito, Maurizio; Cantile, Monica; Collina, Francesca; Scognamiglio, Giosue; Cerrone, Margherita; La Mantia, Elvira; Barbato, Antonio; Liguori, Giuseppina; Botti, Gerardo
Abstract
Purpose: Triple-negative breast cancer, has a significant clinical relevance being associated with a shorter median time to relapse and death and does not respond to endocrine therapy or other available targeted agents. For this reason, identifying the molecular pathways associated with increased aggressiveness, for example the presence of stem cell populations within the tumor and alteration of genes associated with cell cycle regulation represents an important objective in the clinical research into this neoplasm. Methods: To investigate the role of cell cycle progression inhibitor Geminin in triple-negative breast cancers and its potential correlation with stem-like phenotype of this neoplasm, we used tissue microarray technology to build a specific triple-negative breast cancer tissue micro-array. Geminin and cancer stem cell marker CD133 expression was further investigated at the mRNA level for selected breast tumor samples through real-time polymerase chain reaction quantification. Results: Our results showed that CD133 expression was significantly associated to high Geminin expression (p=0.017), a strong association between Ki-67 and tumor grade (p=0.020) and an inverse association between Geminin expression and lymphonode metastases (p=0.058), and a trend of statistically significance between Geminin marker expression and survival of triple-negative breast cancer patients (p=0.076). Conclusion: The strong association between the expression of CD133 and Geminin could be useful in molecular stratification of breast tumors and in particular of triple-negative breast cancers.