engleski

Inhibition of SKOV-3 ovarian cancer cell proliferation by a C-terminal p21 fragment attached to thermally responsive Bac-7-ELP1

Current treatment of solid tumors is limited by normal tissue tolerance and inherent tumor radio or chemo-resistance, resulting in a narrow therapeutic index. To overcome some of these limitations, it is necessary to consider alternative targeted therapeutic approaches for localized tumors that increase the specificity and efficacy and reduce the cytotoxicity in normal tissues. In order to minimize nonspecific toxicity, we developed thermally responsive polypeptide inhibitors of the cell cycle, which can be targeted to the tumor site by applying local hyperthermia and inhibit proliferation of cancer cells. The design of this thermally responsive polypeptide is based on elastin-like polypeptide (ELP), which is soluble in aqueous solution below physiological temperature 37 °C, but aggregates when the temperature is raised above 41 °C. Uptake of therapeutic macromolecules such as ELP into live eukaryotic cells is hindered by the lipophilic nature of the plasma membrane. One approach for delivering macromolecules or proteins into the target cells is to couple them to cell penetrating peptides (CPP). Therefore, we used a small CPP, Bac-7, fused to the thermally responsive elastin like polypeptide (ELP). The coding sequence for ELP was also modified by the addition of a small therapeutic peptide derived from p21, which acts as a cyclin-CDK inhibitor. The designed polypeptide (Bac-ELP1-p21) was then expressed and purified from E. coli. While 1 hour incubation with Bac-ELP1-p21 at 37 oC did not have any effect on SKOV-3 cell proliferation, use of hyperthermia inhibited the total cell number and cell proliferation rate by 80%. 24 hours after cell treatment, Bac-ELP1-p21 displayed a nuclear distribution and induced temperature dependent caspase activation. Cell cycle analysis revealed S and G2/M phase accumulation at the expense of G1 phase in cells treated at 42 oC as compared to 37 oC. Cell cycle inhibition was accompanied by a decrease in Rb phosphorylation levels in cells treated at 42 oC as compared to treatment at 37 oC, as confirmed by Western blot. In summary, we have shown that Bac-ELP1-p21 inhibits cell proliferation in response to hyperthermia, indicating that it has great potential as a thermally responsive targeted therapeutic.

ELP; targeted delivery; solid tumors

Cancer Prevention Journals Portal is a virtual journal featuring prevention articles published in the six AACR journals: - Cancer Research, - Clinical Cancer Research, - Cancer Epidemiology, Biomarkers & Prevention, - Clinical Prevention Research, - Molecular Cancer Therapeutics, - Molecular Cancer Research Molim upisati rad u izvornom izdanju, uz napomenu da je kratko priopćenje o radu tiskano u ...... Admin (2009-09-03)