Abstract P054

The Kinase CK2 is deregulated and targetable in classical Hodgkin Lymphoma

Introducation: CK2 is a pleiotropic kinase consisting of 2 catalytic (a) and 2 regulatory (b) subunits, usually overexpressed, that sustains cancer signaling cascades through the activation of NF-kB, PI3K and STAT pathways. Considering that NF-kB, STAT and PI3K pathways are key players in Hodgkin lymphoma (HL), it is likely that CK2 might play a role in the pathogenesis of this disease.

Methods: Experiments were performed and replicated at least for five times employing 4 HL cell lines (L-428, L-540, KM-H2 and HDLM-1) cultured in RPMI. CK2a, CK2b, RelA-Serine (S)529, RelA, PARP, AKT-S473, AKT, STAT3-S727, STAT3, tubulin, ubiquitin expression levels were evaluated by western blot analysis (WB). Silmitasertib and bortezomib were used as CK2a and proteasome inhibitors. Apoptosis was assessed by Annexin V/Propidium iodide assay and PARP cleavage by WB. Immunohistochemistry (IHC) for CK2a and CK2b was performed on formalin fixed paraffin embedded sections of lymph-nodes from patients with HL, indolent and aggressive NHL. Chou-Talalay methods was used to calculate the combination index (C.I.) of two drugs.

Results: By WB and IF we found that all the 4 HL cell lines expressed higher levels of CK2a, but not CK2b, as compared to normal B lymphocytes (p<0.001). By IHC on 35 patients’ lymph-nodes, we confirmed that CK2a but not CK2b was highly expressed in Reed-Sternberg cells. In addition, patients with lower levels of CK2b display a better progression-free survival (p<0.05). The unbalance between a and b subunits was not observed in low or high-grade NHL (p<0.001). Furthermore, we observed that mRNA levels of both CSNK2A and CSNK2B were similar to normal B lymphocytes, and that proteasome inhibition with bortezomib caused the upregulation of CK2b. AKT, RelA and STAT3 were constitutively phosphorylated in HL at their activatory S-residue (S473, S529, and S727 respectively). Treatment of HL cell lines with silmitasertib caused down-regulation of these phospho-serine proteins, time and dose-dependent apoptosis (p<0.0001). In addition, we found that silmitasertib did not modulate surface CD30 and had a synergistic anti-apoptotic effect in combination with monomethyl auristatin E (C.I.<1)

Conclusions: We demonstrated that CK2a is overexpressed, active, induced key pro-survival signals in HL, and its inhibition trigger apoptosis. CK2b is likely downregulated due to proteasome degradation. These preliminary data suggest that CK2 might be a new therapeutic target in HL.


Andrea Visentin, Edoardo Ruggeri, Federica Frezzato, Marco Pizzi, Alessandro Cellini, Francesco Angotzi, Chiara Adele Cavarretta, Valeria Ruocco, Stefano Pravato, Filippo Severin, Monica Facco, Sabrina Manni, Francesci Piazza, Livio Trentin