TY - JOUR
T1 - Therapeutically targeting cyclin D1 in primary tumors arising from loss of Ini1
AU - Smith, Melissa E.
AU - Cimica, Velasco
AU - Chinni, Srinivasa
AU - Jana, Suman
AU - Koba, Wade
AU - Yang, Zhixia
AU - Fine, Eugene
AU - Zagzag, David
AU - Montagna, Cristina
AU - Kalpana, Ganjam V.
PY - 2011/1/4
Y1 - 2011/1/4
N2 - Rhabdoid tumors (RTs) are rare, highly aggressive pediatric malignancies with poor prognosis and with no standard or effective treatment strategies. RTs are characterized by biallelic inactivation of the INI1 tumor suppressor gene. INI1 directly represses CCND1 and activates cyclin-dependent kinase (cdk) inhibitors p16Ink4a and p21CIP. RTs are exquisitely dependent on cyclin D1 for genesis and survival. To facilitate translation of unique therapeutic strategies, we have used genetically engineered, Ini1 +/- mice for therapeutic testing. We found that PET can be used to noninvasively and accurately detect primary tumors in Ini1+/- mice. In a PET-guided longitudinal study, we found that treating Ini1+/- mice bearing primary tumors with the pan-cdk inhibitor flavopiridol resulted in complete and stable regression of some tumors. Other tumors showed resistance to flavopiridol, and one of the resistant tumors overexpressed cyclin D1, more than flavopiridol-sensitive cells. The concentration of flavopiridol used was not sufficient to down-modulate the high level of cyclin D1 and failed to induce cell death in the resistant cells. Furthermore, FISH and PCR analyses indicated that there is aneuploidy and increased CCND1 copy number in resistant cells. These studies indicate that resistance to flavopiridol may be correlated to elevated cyclin D1 levels. Our studies also indicate that Ini1+/- mice are valuable tools for testing unique therapeutic strategies and for understanding mechanisms of drug resistance in tumors that arise owing to loss of Ini1, which is essential for developing effective treatment strategies against these aggressive tumors.
AB - Rhabdoid tumors (RTs) are rare, highly aggressive pediatric malignancies with poor prognosis and with no standard or effective treatment strategies. RTs are characterized by biallelic inactivation of the INI1 tumor suppressor gene. INI1 directly represses CCND1 and activates cyclin-dependent kinase (cdk) inhibitors p16Ink4a and p21CIP. RTs are exquisitely dependent on cyclin D1 for genesis and survival. To facilitate translation of unique therapeutic strategies, we have used genetically engineered, Ini1 +/- mice for therapeutic testing. We found that PET can be used to noninvasively and accurately detect primary tumors in Ini1+/- mice. In a PET-guided longitudinal study, we found that treating Ini1+/- mice bearing primary tumors with the pan-cdk inhibitor flavopiridol resulted in complete and stable regression of some tumors. Other tumors showed resistance to flavopiridol, and one of the resistant tumors overexpressed cyclin D1, more than flavopiridol-sensitive cells. The concentration of flavopiridol used was not sufficient to down-modulate the high level of cyclin D1 and failed to induce cell death in the resistant cells. Furthermore, FISH and PCR analyses indicated that there is aneuploidy and increased CCND1 copy number in resistant cells. These studies indicate that resistance to flavopiridol may be correlated to elevated cyclin D1 levels. Our studies also indicate that Ini1+/- mice are valuable tools for testing unique therapeutic strategies and for understanding mechanisms of drug resistance in tumors that arise owing to loss of Ini1, which is essential for developing effective treatment strategies against these aggressive tumors.
KW - Atypical teratoid/rhabdoid tumors
KW - Genetically engineered mouse model
KW - SMARCB1
KW - hSNF5
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U2 - 10.1073/pnas.0913297108
DO - 10.1073/pnas.0913297108
M3 - Article
C2 - 21173237
AN - SCOPUS:78651106536
SN - 0027-8424
VL - 108
SP - 319
EP - 324
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 1
ER -