The flavonoid TL-2-8 induces cell death and immature mitophagy in breast cancer cells via abrogating the function of the AHA1/Hsp90 complex

Abstract

The flavonoid quercetin exhibits significant anticancer activities with few side effects. In the current study, we characterized TL-2-8, a quercetin derivative, as a novel anticancer agent in vitro and in vivo. Cell proliferation and viability were assessed using Cell Counting Kit-8 and CellTiter-Blue assay, respectively. Cell death was examined using PI staining or a TUNEL assay. Mitophagy was determined by measuring autophagic flux and by confocal imaging. Protein expression was examined by Western blotting. We found that TL-2-8 selectively inhibited the proliferation and decreased the viability of various cancer cells (the anti-proliferation IC 50 values in MDA-MB-231, MDA-MB-468 and MCF-7 breast cancer cells at 72 h were 8.28, 8.56, and 9.58 μmol/L, respectively), and it displayed only slight cytotoxicity against normal MCF-10A and HEK-293 cells. In MDA-MB-231 and MDA-MB-468 breast cancer cells, TL-2-8 treatment induced the degradation of multiple Hsp90 client proteins without inducing Hsp70. TL-2-8 (3, 6, 12 μmol/L) dose-dependently inhibited the expression of AHA1, an activator of Hsp90 ATPase, and decreased Hsp90-AHA1 complex formation, leading to decreased Hsp90 chaperone function and reduced polo-like kinase 1 (PLK1) signaling. Consequently, impaired mitophagy was induced via the downregulation of lysosomal-associated membrane protein 2 (LAMP2). The in vivo anticancer effects of TL-2-8 were evaluated in an MDA-MB-231 breast cancer xenograft model, which was treated with TL-2-8 (25, 50, 100 mg·kg -1 ·d -1 , po). Administration of TL-2-8 resulted in tumor growth inhibition rates of 37.9%, 58.9% and 70.9%, respectively, whereas quercetin treatment (100 mg·kg -1 ·d -1 , po) produced only a lower tumor growth inhibition rate (49.5%). Furthermore, TL-2-8 treatment significantly extended the lifespan of mice bearing MDA-MB-231 breast cancer cell xenografts. Our results demonstrate that TL-2-8 induces significant cell death and immature mitophagy in breast cancer cells in vitro and in vivo via AHA1 abrogation.

Quercetin‐mediated regulation of signal transduction cascades and microRNAs: Natural weapon against cancer

“…These findings highlighted the role of ER stress as a "double-edged sword" in quercetin-mediated apoptosis in ovarian cancer cells. 7,8 As shown in Figure 1A, quercetin markedly reduced STAT3 phosphorylation at the 705th tyrosine residue and 727th serine residue in BC3 and BCBL1 cells. Quercetin worked synergistically with bortezomib against primary effusion lymphoma cells.…”

“…7,8 Furthermore, autophagy inhibitor 3-methyladenine (3-MA) enhanced quercetin-mediated tumor suppressive effects in mice xenografted with ovarian cancer cells. Quercetin was noted to activate protective autophagy simultaneously by activating the p-STAT3/ Bcl-2 axis.…”

“…44 Dextran-aldehyde-quercetin conjugates were noted to be superior in efficacy as compared with nonconjugated quercetin. 7,8 Hsp90 client interactions have been quantitatively analyzed, and data clearly suggested that Hsp90 assembled with different cochaperones and synchronously coordinated the maturation of its client proteins. 19,20 Biologically active (poly(phenylalanine)-b-poly(L-histidine)-b-poly(ethylene glycol) polypeptide nanoconstructs were used for the delivery of payload consisting of doxorubicin and quercetin.…”

“…45 Quercetin loaded nanoliposomes induced regression of tumors without hepatic toxicity or renal dysfunctions in Balb/c mice xenografted with U14 cervical cancer cells. 7,8 7 | CLINICAL TRIALS OF QUERCETIN Despite unique biological and pharmacological properties, clinical trials related to the evaluation of true potential of quercetin as an anticancer agent are limited. 46 Smartly designed pH-sensitive nanovehicles had precisely tailored drugto-carrier ratios that facilitated release of the drug in a controlled manner.…”

“…It selectively inhibited proliferation of MDA-MB-231, MCF-7, and MDA-MB-468 BCa cells. 7,8 Hsp90 client interactions have been quantitatively analyzed, and data clearly suggested that Hsp90 assembled with different cochaperones and synchronously coordinated the maturation of its client proteins. TL-2-8 triggered degradations of multiple Hsp90 client proteins in MDA-MB-468 and MDA-MB-231 BCa cells.…”