OBJECTIVETo investigate the effect of CAL-101, a selective inhibitor of PI3Kδ, in combination with bortezomib on the proliferation and apoptosis in human mantle cell lymphoma cell lines Z138, HBL-2 and Jeko-1 in vitro, to explore its mechanisms and provide the foundation for effective treatment strategies against mantle cell lymphoma.

METHODSMTT assay was applied to detect the inhibitory effects of CAL-101 and bortezomib either alone or combined on Z138, HBL-2 and Jeko-1 cells. Calcusyn software was used to analyze the synergistic cytotoxicity. Western blot was used to detect the expression of PI3K-p110σ and p-Akt, Akt, p-ERK and ERK proteins after the cells were exposed to different concentrations of CAL-101. Flow cytometry was employed to assess the apoptosis rate. NF-κB kit was used to determine the changes of location of NF-κB P65, and Western blot was applied to detect the level of caswpase-3 and the phosphorylation of Akt in different groups.

RESULTSCAL-101 and BTZ inhibited the proliferation of Z138, HBL-2 and Jeko-1 cells in a dose- and time-dependent manner. CAL-101/BTZ combination induced significantly synergistic cytotoxicity in the MCL cells. The results of Western blot assay showed that CAL-101 significantly blocked the phosphorylation of Akt and ERK in the MCL cell lines. In addition, CAL-101 combined with BTZ induced pronounced apoptosis (P < 0.01). For example, after the Z138 cells exposed to the drugs for 48 h, the apoptosis rates of the control, CAL-101, BTZ and CAL-101 + BTZ groups were: (2.6 ± 1.8)%, (40.0 ± 3.0)%, (34.0 ± 1.0)%, and (67.4 ± 1.0)%, respectively; and when drug treatment was given to HBL-2 cells over 96 h, the apoptosis rates of these four cell groups were (7.4 ± 0.6)%, (30.7 ± 5.7)%, (12.0 ± 1.0)%, and (85.0 ± 4.0)%, respectively. The combination therapy contributed to the enhanced inactivity of nuclear factor-κB (NF-κB) and Akt inactivation in the MCL cell lines (P < 0.05), however, the casepase-3 activity was up-regulated.

CONCLUSIONSThe combination of CAL-101 and bortezomib is muchmore effective in inhibiting proliferation and promoting apoptosis of mantle cell lymphoma cell lines (Z138, HBL-2 and Jeko-1), which may be mediated through inhibiting PI3K/Akt signaling pathway and the transcription of NF-κB.

Antineoplastic Agents ; pharmacology ; Antineoplastic Combined Chemotherapy Protocols ; pharmacology ; Apoptosis ; drug effects ; Blotting, Western ; Boronic Acids ; Bortezomib ; pharmacology ; Caspase 3 ; metabolism ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Class Ia Phosphatidylinositol 3-Kinase ; antagonists & inhibitors ; Dose-Response Relationship, Drug ; Drug Synergism ; Formazans ; Humans ; Lymphoma, Mantle-Cell ; drug therapy ; pathology ; MAP Kinase Signaling System ; drug effects ; NF-kappa B ; metabolism ; Neoplasm Proteins ; metabolism ; Phosphatidylinositol 3-Kinases ; metabolism ; Phosphorylation ; drug effects ; Proto-Oncogene Proteins c-akt ; metabolism ; Purines ; administration & dosage ; pharmacology ; Pyrazines ; Quinazolinones ; administration & dosage ; pharmacology ; Signal Transduction ; Software ; Tetrazolium Salts