CK2 and PI3K are direct molecular targets of quercetin in chronic lymphocytic leukaemia

Abstract

Despite the encouraging results of the innovative therapeutic treatments, complete remission is uncommon in patients affected by chronic lymphocytic leukaemia, which remains an essentially incurable disease. Recently, clinical trials based on BH3-mimetic drugs showed positive outcomes in subjects with poor prognostic features. However, resistance to treatments occurs in a significant number of patients. We previously reported that the multi-kinase inhibitor quercetin, a natural flavonol, restores sensitivity to ABT-737, a BH3-mimetic compound, in both leukemic cell lines and B-cells isolated from patients. To identify the molecular target of quercetin, we employed a new cell line, HG3, obtained by immortalization of B-cells from a chronic lymphocytic leukaemia patient at the later stage of disease. We confirmed that quercetin in association with ABT-737 synergistically enhances apoptosis in HG3 (combination index < 1 for all fractions affected). We also reported that the cellular uptake of quercetin is extremely rapid, with an intracellular concentration of about 38.5 ng/106 cells, after treatment with 25 μM for 5 min. We demonstrated that the activity of protein kinase CK2, which positively triggers PI3K/Akt pathway by inactivating PTEN phosphatase, is inhibited by quercetin immediately after its addition to HG3 cells (0–2 min). PI3K activity was also inhibited by quercetin within 60 min from the treatment. The combined inhibition of CK2 and PI3K kinase activities by quercetin restored ABT-737 sensitivity and increased lethality in human leukemia cells.

Alternaria toxins as casein kinase 2 inhibitors and possible consequences for estrogenicity: a hybrid in silico/in vitro study

“…This inhibition was significant for ≥ 1 µM and the IC 50 was calculated to reside at 5.1 µM. 10 µM of quercetin, which was previously reported to act as a CK2 inhibitor (Russo et al 2017), served as a positive control and suppressed CK2 activity by 94%.…”

Sulfur-containing histidine compounds inhibit γ-glutamyl transpeptidase activity in human cancer cells

“…Autophagy was monitored using the Cyto-ID Autophagy Detection kit (ENZO Life Science, Milan, Italy) as described (56,57) using quercetin as the positive control. After incubation with ovo (20 -100 M), HepG2 or HG3 cells (2 ϫ 10 4 ) were washed and incubated with the autophagy detection marker (Cyto-ID) and nuclear dye (Hoechst 33342).…”

QSAR Model of Indeno[1,2-b]indole Derivatives and Identification of N-isopentyl-2-methyl-4,9-dioxo-4,9-Dihydronaphtho[2,3-b]furan-3-carboxamide as a Potent CK2 Inhibitor

“…It is involved in different intracellular signaling pathways and is also known to be an apoptosis-suppressor in cancer cells [2,3]. CK2 was shown to be overexpressed in cells of different cancer types, including prostate, breast, and colon tumors [4][5][6]. The overexpression of CK2 is not only related to cancer, but also to the development of other diseases, such as autoimmune diseases, cardiac hypertrophy, and central nervous system (CNS) diseases [7][8][9][10].…”