TY - JOUR
T1 - CDK4/6 Inhibition Induces Senescence and Enhances Radiation Response by Disabling DNA Damage Repair in Oral Cavity Squamous Cell Carcinoma
AU - Shrivastava, Nitisha
AU - Chavez, Claudia Gutierrez
AU - Li, Daniel
AU - Mehta, Vikas
AU - Thomas, Carlos
AU - Fulcher, Cory D.
AU - Kawachi, Nicole
AU - Bottalico, Danielle M.
AU - Prystowsky, Michael B.
AU - Basu, Indranil
AU - Guha, Chandan
AU - Ow, Thomas J.
N1 - Publisher Copyright:
© 2023 by the authors.
PY - 2023/4
Y1 - 2023/4
N2 - Purpose: HPV(−) OCSCC resists radiation treatment. The CDKN2A gene, encoding p16INK4A, is commonly disrupted in OCSCC. p16 inhibits CDK4/CDK6, leading to cell cycle arrest, but the biological sequelae of CDK4/6 inhibition in OCSCC remains understudied. This study examines whether inhibition of CDK4/6 enhances radiation response in OCSCC. Methods: MTT assays were performed in OCSCC cell lines HN5 and CAL27 following treatment with palbociclib. Clonogenic survival and synergy were analyzed after radiation (RT-2 or 4Gy), palbociclib (P) (0.5 µM or 1 µM), or concurrent combination treatment (P+RT). DNA damage/repair and senescence were examined. CDK4/6 were targeted via siRNA to corroborate P+RT effects. Three-dimensional immortalized spheroids and organoids derived from patient tumors (conditionally reprogrammed OCSCC CR-06 and CR-18) were established to further examine and validate responses to P+RT. Results: P+RT demonstrated reduced viability and synergy, increased β-gal expression (~95%), and ~two-fold higher γH2AX. Rad51 and Ku80 were reduced after P+RT, indicating impairment of both HR and NHEJ. siCDK4/6 increased senescence with radiation. Spheroids showed reduced proliferation and size with P+RT. CR-06 and CR-18 further demonstrated three-fold reduced proliferation and organoids size with P+RT. Conclusion: Targeting CDK4/6 can lead to improved efficacy when combined with radiation in OCSCC by inducing senescence and inhibiting DNA damage repair.
AB - Purpose: HPV(−) OCSCC resists radiation treatment. The CDKN2A gene, encoding p16INK4A, is commonly disrupted in OCSCC. p16 inhibits CDK4/CDK6, leading to cell cycle arrest, but the biological sequelae of CDK4/6 inhibition in OCSCC remains understudied. This study examines whether inhibition of CDK4/6 enhances radiation response in OCSCC. Methods: MTT assays were performed in OCSCC cell lines HN5 and CAL27 following treatment with palbociclib. Clonogenic survival and synergy were analyzed after radiation (RT-2 or 4Gy), palbociclib (P) (0.5 µM or 1 µM), or concurrent combination treatment (P+RT). DNA damage/repair and senescence were examined. CDK4/6 were targeted via siRNA to corroborate P+RT effects. Three-dimensional immortalized spheroids and organoids derived from patient tumors (conditionally reprogrammed OCSCC CR-06 and CR-18) were established to further examine and validate responses to P+RT. Results: P+RT demonstrated reduced viability and synergy, increased β-gal expression (~95%), and ~two-fold higher γH2AX. Rad51 and Ku80 were reduced after P+RT, indicating impairment of both HR and NHEJ. siCDK4/6 increased senescence with radiation. Spheroids showed reduced proliferation and size with P+RT. CR-06 and CR-18 further demonstrated three-fold reduced proliferation and organoids size with P+RT. Conclusion: Targeting CDK4/6 can lead to improved efficacy when combined with radiation in OCSCC by inducing senescence and inhibiting DNA damage repair.
KW - CDK4
KW - CDK6
KW - DNA repair
KW - PD-0332991 (palbociclib)
KW - head and neck squamous cell carcinoma (HNSCC)
KW - oral cavity
KW - organoids
KW - radiosensitizing
KW - senescence
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UR - http://www.scopus.com/inward/citedby.url?scp=85152961959&partnerID=8YFLogxK
U2 - 10.3390/cancers15072005
DO - 10.3390/cancers15072005
M3 - Article
AN - SCOPUS:85152961959
SN - 2072-6694
VL - 15
JO - Cancers
JF - Cancers
IS - 7
M1 - 2005
ER -