10 research outputs found
A COMBINATION OF BORTEZOMIB WITH CX-4945, A CASEIN KINASE 2 (CK2) INHIBITOR, HAS SYNERGISTIC CYTOTOXIC EFFECTS IN ACUTE LYMPHOBLASTIC LEUKEMIA (ALL) CELL LINES
Introduction. The proteasome inhibitor bortezomib is a new treatment
option for patients with refractory or relapsed ALL, particularly when
used in combination with conventional chemotherapy or other targeted
agents. Indeed, a limited efficacy of bortezomib alone in ALL
patients has been reported. A terminal pro-apoptotic endoplasmic reticulum
(ER) stress/unfolded protein response (UPR) is one of the several
mechanisms of bortezomib-induced apoptosis. CX-4945, a potent CK2
inhibitor, has been found to induce apoptotic cell death in T-ALL preclinical
models, via perturbation of ER/UPR pathway. Here, we have
explored the cytotoxic effects of a bortezomib/CX-4945 combination
in a panel of B- and T-ALL cell lines. Methods. B- (KOPN-8, NALM-6,
RS4;11) and T- (MOLT-4, Jurkat, CEM-R) ALL cell lines were pretreated
with bortezomib (Selleck Chemicals, Houston TX, USA), for six
hours and then with CX-4945 (Selleck Chemicals, Houston TX, USA),
for 16/24 hours. MTT assays were performed to analyze cell viability.
Apoptosis induction was evaluated by Annexin V/PI staining and flow
cytometric analysis. Protein expression was studied by western blot.
Results. Cells were cultured in the presence of bortezomib or CX-4945,
either alone or in combination at a fixed ratio. The combined treatment
was more effective in reducing cell viability in all B-ALL cell lines
and in MOLT-4 cells. Annexin V/PI staining was performed; interestingly,
no synergism was detected if the two drugs were administered
together since the beginning of treatment. In response to treatment
with 2.5 nM bortezomib followed by 5 ÎĽM CX-4945, we detected an
increase in apoptosis in B-ALL cell lines and in MOLT-4 cells after 24 h.
Western blot analysis for the cleaved forms of caspase-3 and PARP, confirmed
a higher apoptosis induction by the combined treatment. A
reduction in anti-apoptotic Bcl2 concomitant with an increase in proapoptotic
Bax, suggested that bortezomib/CX-4945 treatment caused
a mitochondrial apoptosis. IRE1a and CHOP (established markers of ER
stress/UPR-mediated apoptosis) levels increased in response to the combined
treatment, in contrast the expression of GRP78/BIP (a marker of
UPR activation) decreased, suggesting that a potential mechanism by
which the drug combination induced cell death, involved ER stress
induction by bortezomib and the inability to respond by adequate activation
of the UPR signaling which was blocked by CX-4945. Conclusions.
Here, we demonstrated that the proteasome inhibitor bortezomib
and the CK2 inhibitor CX-4945 interact in a synergistic manner to
induce apoptosis both in B- and in T-ALL cell lines. Drug cytotoxicity
was associated with modulation of the ER stress/UPR signaling pathway.
Importantly, the synergism was observed only when bortezomib
treatment preceded CX-4945 administration. Therefore, our findings
support clinical application of bortezomib in combination with CX-
4945 in B- and T-ALL treatment
PI3K pan-inhibition impairs more efficiently proliferation and survival of T-cell acute lymphoblastic leukemia cell lines when compared to isoform-selective PI3K inhibitors
Therapeutic targeting of Polo-like kinase-1 and Aurora kinases in T-cell acute lymphoblastic leukemia
Polo-like kinases (PLKs) and Aurora kinases (AKs) act as key cell cycle regulators in healthy human cells. In cancer, these protein kinases are often overexpressed and dysregulated, thus contributing to uncontrolled cell proliferation and growth. T-cell acute lymphoblastic leukemia (T-ALL) is a heterogeneous malignancy arising in the thymus from T-cell progenitors. Primary chemoresistant and relapsed T-ALL patients have yet a poor outcome, therefore novel therapies, targeting signaling pathways important for leukemic cell proliferation, are required. Here, we demonstrate the potential therapeutic effects of BI6727, MK-5108, and GSK1070916, three selective inhibitors of PLK1, AK-A, and AK-B/C, respectively, in a panel of T-ALL cell lines and primary cells from T-ALL patients. The drugs were both cytostatic and cytotoxic to T-ALL cells by inducing G2/M-phase arrest and apoptosis. The drugs retained part of their pro-apoptotic activity in the presence of MS-5 bone marrow stromal cells. Moreover, we document for the first time that BI6727 perturbed both the PI3K/Akt/mTORC2 and the MEK/ERK/mTORC1 signaling pathways, and that a combination of BI6727 with specific inhibitors of the aforementioned pathways (MK-2206, CCI-779) displayed significantly synergistic cytotoxic effects. Taken together, our findings indicate that PLK1 and AK inhibitors display the potential for being employed in innovative therapeutic strategies for improving T-ALL patient outcome. © 2014 Landes Bioscience
ASSESSMENT OF THE EFFECT OF SPHINGOSINE KINASE INHIBITORS ON APOPTOSIS, UNFOLDED PROTEIN RESPONSE AND AUTOPHAGY OF T-ACUTE LYMPHOBLASTIC LEUKEMIA CELLS: INDICATIONS FOR NOVEL THERAPEUTICS
Introduction. Sphingosine 1-phosphate (S1P) is involved in many
processes such as cell survival, growth, migration, and cancer. S1P is
formed by the phosphorylation of sphingosine by sphingosine kinase
1 (SK1) or sphingosine kinase 2 (SK2). While the role of SK1 in cancer
is well established, the role of SK2 in regulating apoptosis is still a matter
of debate, even though emerging evidence has highlighted the
importance of SK2 in cancer. Therefore, SKs represent a promising target
for cancer therapy. Recently, the importance of S1P in hematological
malignancies has been described. Here, we analyze the therapeutic
effects of 2-(p-Hydroxyanilino)-4-(p-chlorophenyl)thiazole (SKi), an
SK1/2 inhibitor, and (R)-FTY720 methyl ether (ROMe), a SK2-selective
inhibitor, in T-ALL cell lines. Methods. T- ALL cell lines (Molt-4, Jurkat,
CEM-R) were treated with SKi and ROMe for 40 h, then MTT assays
were performed to analyze cell viability. Apoptosis induction was evaluated
by Annexin V/PI staining. Protein expression was studied by
western blot (WB). Results. SKi and ROMe induced a decrease in cell viability,
as demonstrated by MTT assays. Annexin-V/PI staining and flow
cytometric analysis of cells treated with a SKi concentration equivalent
to the IC50 documented the occurrence of apoptotic cell death. This
was confirmed by WB analysis for caspase and PARP cleavage in all the
cell lines. However, we also observed a SKi-induced autophagy by
means of WB and transmission electron microscopy analysis in Jurkat
and CEM-R cells. We then analyzed the expression of ER stress/UPR
hallmarks. SKi activated the ER stress/UPR pathway and this occurred
following apoptosis and correlated with autophagy. The combination
of SKi and chloroquine (an autophagy inhibitor) induced a decrease in
cell viability, indicating that the UPR/autophagic response is likely to be
a protective mechanism. In Molt-4 cells, we detected an increase in SK1
expression after 40 h of treatment with SKi, that could represent an
attempt of cells to escape SKi-induced apoptosis, as high SK1 expression
is known to enhance cell growth and survival. Notably, SKi synergized
with vincristine at concentrations of SKi that were much below
its respective IC50, suggesting that vincristine sensitized T-ALL cells to
SKi and that combining chemotherapeutic agents with SK inhibitors
could be feasible in the treatment of T-ALL. Finally, ROMe treatment
induced an autophagic type of cell death. Conclusions. We report herein
that SKi and ROMe affect T-ALL cell viability, but they exert their
effects through different mechanisms. While ROMe induces an
autophagic cell death, SKi induces apoptosis. Moreover, for the first
time, we demonstrated that SKi activates an ER stress/UPR pathway in
T-ALL cells and this is linked with a protective autophagic response.
Thus, our findings indicate that SK1 or SK2 may represent potential
targets for treating T-ALL, thereby enabling better management of this
cancer
Therapeutic targeting of Polo-like kinase-1 and Aurora kinases in T-cell acute lymphoblastic leukemia
Long-term health-related quality of life and psychological adjustment in children after haemolytic-uraemic syndrome
BACKGROUND: In children after haemolytic-uraemic syndrome (HUS), little is known about long-term health-related quality of life (HRQoL) and psychological adjustment as defined by behavioural problems, depressive symptoms and post-traumatic stress symptoms.
METHODS: Sixty-two paediatric patients with a history of HUS were included in this study. Medical data of the acute HUS episode were retrieved retrospectively from hospital records. Data on the clinical course at study investigation were assessed by clinical examination and laboratory evaluation. HRQoL and psychological adjustment data were measured by standardised, parent- and self-reported questionnaires.
RESULTS: Haemolytic-uraemic syndrome was diagnosed at a mean of 6.5 years before the initiation of the study (standard deviation 2.9, range 0.1-15.7) years. Among the preschool children, parents reported that their child was less lively and energetic (HRQoL emotional dimension), while no increased behavioural problems were reported. In the school-age children, self- and proxy-reported HRQoL was well within or even above the norms, while increased total behavioural problems were found. The school-age children reported no increased depression scores. Also none of the children met the criteria for full or partial HUS-associated posttraumatic stress disorder.
CONCLUSIONS: Healthcare providers should be particularly alert to behavioural problems in school-age children with a history of HUS and to lower HRQoL in preschool children
Hemolytic-uremic syndrome in Switzerland: a nationwide surveillance 1997-2003
Hemolytic-uremic syndrome (HUS) is a leading cause of acute renal failure in childhood. In its typical presentation, it is preceded by an episode of diarrhea mostly due to Shiga-toxin-producing Escherichia coli. There is important geographical variation of many aspects of this syndrome. Nationwide data on childhood HUS in Switzerland have not been available so far. In a prospective national study through the Swiss Pediatric Surveillance Unit 114 cases (median age 21 months, 50% boys) were reported between April 1997 and March 2003 by 38 pediatric units (annual incidence 1.42 per 10(5) children < or =16 years). Shiga-toxin-producing E. coli were isolated in 32 (60%) of tested stool samples, serotype O157:H7 in eight. Sixteen children presented with only minimal renal involvement, including three with underlying urinary tract infection. Six patients presented with atypical hemolytic-uremic syndrome, and six with HUS due to invasive Streptococcus pneumoniae infection. Mortality was 5.3%, including two out of six children with S. pneumoniae infection. The severity of thrombocytopenia and the presence of central nervous system involvement significantly correlated with mortality. In conclusion, childhood HUS is not rare in Switzerland. Contrasting other countries, E. coli O157:H7 play only a minor role in the etiology. Incomplete manifestation is not uncommon