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Sensitization of Cancer Cells to Chemotherapy or Olaparib by ILK Inhibition

Kuo, Yi-Chiu
http://rave.ohiolink.edu/etdc/view?acc_num=osu1480534020796613

Abstract Details

2016, Doctor of Philosophy, Ohio State University, Pharmaceutical Sciences.
Part I. Breast cancer, the most commonly diagnosed cancer, ranks as the second cause of cancer death among women in the United States. Chemotherapy combined with radiation and surgery has been adopted to treat breast cancer; however, the development of resistance ultimate leads to disease progression and decreases the survival rate of patients. Thus, it is of utmost importance to develop drugs to sensitize the resistant cells. T315, an integrin-linked kinase (ILK) inhibitor, has an IC50 of 1.5 µM in breast cancer cells MDA-MB-231 and MDA-MB-468. After T315 treatment or ILK knockdown, there is decrease in DNA repair proteins expression detected by western blot. Conversely, ILK overexpression increased DNA repair protein expression. Since ILK is upstream of the AKT-NF-¿B pathway, which has been shown to be associated with DNA repair, overexpression of p65 or myristoylated AKT was used to examine the DNA repair proteins as well. T315-induced ¿-H2AX foci was observed by microscopy, and DR-GFP assay demonstrated the suppression of homologous recombination caused by T315. ILK inhibition induces decrease in DNA repair proteinis through transcriptional regulation based on the results of RT-PCR, promoter reporter assay and CHIP assay. Moreover, clonogenic assay showed that ILK knockdown increased sensitivity to doxorubicin or cisplatin in MCF-7 IL-6 overexpressing cells, which has higher chemotherapeutic resistance and expression of DNA repair-related proteins than MCF-7 cells. T315 treatment or ILK knockdown also sensitized MDA-MB-231 cells to doxorubicin. In summary, the down-regulation of these proteins related with DNA repair by ILK inhibition sensitizes breast cancer cells to chemotherapeutic drugs, confirming that ILK is a target for cancer treatment to counter drug resistance. Part II. Olaparib, the first approved PARP inhibitor by US Food and Drug Administration (FDA) in 2014, shows high clinical response in ovarian cancers that harbor BRCA mutation. Olaparib is indicated as a monotherapy in ovarian cancer patients who have received three or more lines of chemotherapy and have a deleterious BRCA mutation. We then inquired whether olaparib has synergistic effects with T315 in BRCA wild-type breast cancers, since down-regulation of BRCA1 and BRCA2 by T315 is shown in part I of this dissertation. Two ovarian cancer cell lines, SKOV3 and OVCAR3 with wild-type BRCA, were used in this study. T315 showed an IC50 of 2 µM and 4 µM in SKOV3 and OVCAR3, respectively. By western-blotting, T315 or ILK knockdown decreased DNA repair proteins. In clonogenic assay, combined treatment of T315 and olaparib significantly suppressed colony formation and similar results were shown in cells with ILK knockdown combined with olaparib. Additionally, T315 treatment or ILK knockdown potentiates expression ¿-H2AX in cells simultaneously treated with olaparib. Moreover, the severity of DNA damage was measured by the comet assay. Combination of T315 and olaparib increased the mean value of tail DNA percentage compared with individual drug treatments. In short, T315 through ILK inhibition sensitized cancer cells to PARP inhibitors, which suggests cancer patients with wild-type BRCA may also benefit from PARP inhibitors when they are treated with ILK inhibitors simultaneously.
Ching-Shih Chen (Advisor)
114 p.
Pharmacy Sciences
ILK

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Citations

  • Kuo, Y.-C. (2016). Sensitization of Cancer Cells to Chemotherapy or Olaparib by ILK Inhibition [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1480534020796613

    APA Style (7th edition)

  • Kuo, Yi-Chiu. Sensitization of Cancer Cells to Chemotherapy or Olaparib by ILK Inhibition. 2016. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1480534020796613.

    MLA Style (8th edition)

  • Kuo, Yi-Chiu. "Sensitization of Cancer Cells to Chemotherapy or Olaparib by ILK Inhibition." Doctoral dissertation, Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1480534020796613

    Chicago Manual of Style (17th edition)

osu1480534020796613
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© 2016, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.