Inhibition of ubiquitin conjugating enzyme UBE2C reduces proliferation and sensitizes breast cancer cells to radiation, doxorubicin, tamoxifen and letrozole.
OBJECTIVE
The objective of this study was to determine radiation, doxorubicin, tamoxifen and letrozole sensitivity of breast cancer cells in response to functional inhibition of the ubiquitin conjugating enzyme UBE2C.


METHODS
Taqman Real time PCR was performed to measure UBE2C levels in breast cancer cell lines and control HBL100 and HEK293T cells. A dominant negative form of UBE2C (DN-UBE2C) was used to functionally inhibit wild type UBE2C. Cell proliferation and anchorage independent growth were measured by colorimetric and soft agar assays, respectively. Radiation, doxorubicin, tamoxifen and letrozole responses of the cell lines were assessed by colorimetric and clonogenic assays.


RESULTS
Overexpression of UBE2C was observed in all breast cancer cell lines tested using quantitative real time PCR. UBE2C expression was found to be highest in MDAMB231 and relatively lowest in MCF7 cells, compared to control cells. Both the growth rate and the anchorage independent growth of MCF7 and MDAMB231 cells transfected with DN-UBE2C were significantly reduced compared to cells transfected with vector alone. MCF7 and MDAMB231 cells expressing DN-UBE2C were significantly more sensitive to different doses of radiation and doxorubicin compared to both wild type and vector alone transfected cells. In addition, DN-UBE2C transfected MCF7 cells were more sensitive to inhibition by tamoxifen and letrozole compared to wild type and vector alone transfected cells.


CONCLUSIONS
Our results show that inhibition of UBE2C sensitizes breast cancer cells to radiation, doxorubicin and hormone blocking agents. UBE2C may, therefore, serve as a potential therapeutic target aimed at inducing radiation and chemo sensitization.
Department of Molecular Oncology, Cancer Institute (WIA), 38, Sardar Patel Road, Chennai, 600036, India.
Akhilesh
A
Rawat
Gopisetty
G
Gopal
Ganesharaja
G
Selvaluxmy
Thangarajan
T
Rajkumar
D000970:Antineoplastic Agents / Q000494:pharmacology; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D002460:Cell Line; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects* / Q000528:radiation effects; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D004317:Doxorubicin / Q000494:pharmacology*; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D057809:HEK293 Cells; D006801:Humans; D000077289:Letrozole; D061986:MCF-7 Cells; D009570:Nitriles / Q000494:pharmacology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013629:Tamoxifen / Q000494:pharmacology*; D014230:Triazoles / Q000494:pharmacology*; D044763:Ubiquitin-Conjugating Enzymes / Q000235:genetics* / Q000378:metabolism
D000970:Antineoplastic Agents; D009570:Nitriles; D014230:Triazoles; D013629:Tamoxifen; D000077289:Letrozole; D004317:Doxorubicin; C105156:UBE2C protein, human; D044763:Ubiquitin-Conjugating Enzymes