Valproic acid induces apoptosis in human leukemia cells by stimulating both caspase-dependent and -independent apoptotic signaling pathways
Introduction
Accumulating evidence indicates that some members of short chain fatty acids (SCFAs) affect the proliferation and/or the differentiation of a wide variety of tumor cells [1], [2], [3], [4], [5], [6]. For instance, aromatic SCFAs such as butyrate, phenylacetate, and phenylbutyrate, promote differentiation or induce apoptosis in many types of tumor cells including colon cancer [1], [2], head and neck squamous carcinoma [3], renal cell carcinoma [4], neuroblastoma [5], and leukemia [6], [7]. Valproic acid (2-propylpentanoic acid, VPA) is a member of branched SCFAs and has been widely used in the management of various types of epilepsy for decades. As similar to the other members of SCFAs, VPA affects the growth and differentiation of some types of cells. It is reported that VPA induces differentiation in neuroblastoma cells and inhibits their growth [8], [9]. Furthermore, VPA affects the growth of hematopoietic cells. VPA inhibited the formation of normal granulocyte and macrophage colonies at the higher concentration [10]. Tittle et al. showed that VPA inhibited the growth of murine B-lymphoid leukemia cell lines and a human T-lymphoblastic leukemia cell line, Jurkat [11]. The mechanism underlying these effects of VPA on normal and malignant hematopoietic cells is unknown at present.
In this study, we firstly aimed to clarify the effect of VPA on the growth of various human leukemia cell lines and the mechanism underlying it. We demonstrated that VPA induces apoptosis in a variety of human leukemia cell lines in a dose dependent manner. LD50 of the four of nine cell lines tested were within the range that did not inhibit the growth of normal hematopoietic progenitors. It is proposed that there are some apoptotic signaling pathways and with a few exceptions [12], [13], [14], [15], [16], they all activate the family of cysteine proteases known as caspases. Though many anti-cancer drugs are known to induce apoptosis in tumor cells, few are reported to be independent to caspases. If a drug dose induces apoptosis independently to caspases, it might be applicable as an option for the cancer treatment. We show in this study that VPA led the cells to death by stimulating both caspase-dependent and -independent apoptotic signaling pathways. Our findings suggest that VPA may be useful as an anti-leukemic agent without serious toxicity to normal hematopoiesis.
Section snippets
Cell lines
RS4-11, a human B-cell precursor leukemia cell line [17] and a human biphenotypic (B-myeloid) cell line, MV4-11 [18] were obtained from American Type Culture Collection (Manassas, VA). KOCL-33, KOCL-44 and KOPB-26 (B-cell precursor) [19] were kindly gifted by Drs. K. Sugita and S. Nakazawa (Department of Pediatrics, Yamanashi Medical College, Japan). THP-1, a human monocytic leukemia cell line [20], was purchased from Japanese Collection of Research Bioresources (Tokyo, Japan). MOLT-4 [21] and
VPA induces cell death in human leukemia cell lines
To examine the effects of VPA on the growth and survival of human leukemic cells, nine human leukemia cell lines (four B-cell precursor, two T-lymphoid, one myeloid, one monocytic and one biphenotypic cell lines) were cultured with various concentrations of VPA (0–300 μg/ml) for 5 days. As shown in Fig. 1, VPA decreased the number of viable cells in all the cell lines tested in a dose-dependent manner. The sensitivity to VPA was different among the cell lines, and there was no correlation
Discussion
In the present study, we demonstrated that VPA, a member of SCFAs, induces cell death in a variety of human leukemia cell lines including pre-B and T-lymphoid, and myeloid lineages. These results are consistent with the previous report showing that VPA inhibits the growth of murine B-lymphoid cell lines [11]. Among the cell lines tested, two cell lines, MV4-11 and KOCL-44, were completely killed by the clinical dose (100–150 μg/ml) of VPA (Fig. 1). Importantly these two cell lines carry the
Acknowledgements
R. Kawagoe collected, assembled and analyzed the data and drafted the manuscript. H. Kawagoe provided the concept and design. K. Sano obtained the funding provided study materials, gave critical input into the revision, and gave final approval.
References (29)
- et al.
Role of short-chain fatty acids in the prevention of colorectal cancer
Eur. J. Cancer
(1995) - et al.
In vitro differentiation of human neuroblastoma cells induced by sodium phenylacetate
Cancer Lett.
(1993) - et al.
HMBA induces activation of a caspase-independent pathway to overcome P-glycoprotein-mediated multidrug resistance
Blood
(2000) - et al.
Caspase-independent commitment phase to apoptosis in activated blood T-lymphocytes: reversibility at low apoptotic insult
Blood
(2000) - et al.
Human acute leukemia cell line with t(4; 11) chromosomal rearrangement exhibits B-lineage and monocytic characteristics
Blood
(1985) - et al.
Fluorometric and colormetric detection of caspase activity associated with apoptosis
Anal. Biochem.
(1997) - et al.
A combinatorial approach defines specigicities of members of the caspase family and granzyme-B
J. Biol. Chem.
(1997) - et al.
Activation of caspase-8 in drug-induced apoptosis of B-lymphoid cells is independent of CD95/Fas receptor–ligand interaction and occurs downstream of caspase-3
Blood
(2001) - et al.
A novel evidence of different mechanisms of lithium and valproate neuroprotective action on human SY5Y neuroblastoma cells: caspase-3 dependency
Neurosci. Lett.
(2000) - et al.
Sodium butyrate induces apoptosis in human colonic tumour cell lines in a p53-indeoendent pathway: implications for the possible role of dietary fibre in the prevention of large-bowel cancer
Int. J. Cancer.
(1993)
Effects of sodium butyrate on growth, differentiation, and apoptosis in head and neck squamous carcinoma cell lines
Head Neck
Sodium butyrate induces apoptosis in human renal carcinoma cells and synergistic enhances their sensitivity to anti-Fas-mediated cytotoxicity
Int. J. Oncol.
Apoptosis induced by the histone deacetylase inhibitor sodium butyrate in human leukemic lymphblasts
FESEB
Phenylbutyrate-induced G1 arrest and apoptosis in myeloid leukemia cells: structure–function analysis
Leukemia
Cited by (120)
Histone deacetylases inhibitors (HDACis) as novel therapeutic application in various clinical diseases
2017, Progress in Neuro-Psychopharmacology and Biological PsychiatryMechanistic Insights about Sorafenib-, Valproic Acid- and Metformin-Induced Cell Death in Hepatocellular Carcinoma
2024, International Journal of Molecular SciencesThe Diagnostic and Prognostic Values of HOXA Gene Family in Kidney Clear Cell Renal Cell Carcinoma
2022, Journal of Oncology