scholarly journals 9-cis-retinoic acid: effects on normal and leukemic hematopoiesis in vitro

Blood ◽  
1993 ◽  
Vol 81 (4) ◽  
pp. 1009-1016 ◽  
Author(s):  
A Sakashita ◽  
M Kizaki ◽  
S Pakkala ◽  
G Schiller ◽  
N Tsuruoka ◽  
...  
Keyword(s):  
Retinoic Acid ◽  
Cell Lines ◽  
Clonal Growth ◽  
Myelogenous Leukemia ◽  
Leukemic Cells ◽  
Clonal Proliferation ◽  
Normal Individuals ◽  
Cellular Responsiveness ◽  
X Receptors

Retinoic acid exhibits effects on the proliferation and differentiation of many hematopoietic cells. Cellular responsiveness to retinoic acid (RA) is conferred through two distinct classes of nuclear receptors, the RA receptors (RARs) and the retinoid X receptors (RXRs). The RARs bind to both 9-cis- and all-trans-RAs, but 9-cis-RA alone directly binds and activates RXR. This suggested that 9-cis-RA could have expanded hematopoietic activities as compared with all-trans-RA. We compared the abilities of 9-cis- and all-trans-RAs to induce differentiation and inhibit proliferation of three acute myelogenous leukemia (AML) cell lines and fresh leukemic cells from 28 patients and found that: (1) 9-cis-RA in general was more potent than all-trans-RA in suppressing the clonal growth of two AML cell lines and 17 AML samples from patients, including four from individuals with acute promyelocytic leukemia (APL). Eleven leukemic samples, including three from patients with chronic myelogenous or chronic myelomonocytic leukemia, were relatively refractory to both retinoids. (2) The range of activities of both retinoids was similar except that the clonal growth of samples from three AML patients were inhibited by 9-cis-RA, but not by all-trans-RA. (3) Both retinoids inhibited the clonal proliferation of leukemia cells without necessarily inducing their differentiation; in fact, the only fresh AML cells that were able to undergo differentiation were from patients with APL and one individual with M2 AML. (4) Both retinoids enhanced myeloid and erythroid clonal growth from normal individuals, and 9-cis-RA showed slightly more stimulation of the myeloid clonal growth than did the all-trans-RA. Our study suggests that 9-cis-RA is worthy of further study for the treatment of selected individuals with AML.

scholarly journals 9-cis-retinoic acid: effects on normal and leukemic hematopoiesis in vitro

Blood ◽  
1993 ◽  
Vol 81 (4) ◽  
pp. 1009-1016 ◽  
Author(s):  
A Sakashita ◽  
M Kizaki ◽  
S Pakkala ◽  
G Schiller ◽  
N Tsuruoka ◽  
...  
Keyword(s):  
Retinoic Acid ◽  
Cell Lines ◽  
Clonal Growth ◽  
Myelogenous Leukemia ◽  
Leukemic Cells ◽  
Clonal Proliferation ◽  
Normal Individuals ◽  
Cellular Responsiveness ◽  
X Receptors

Abstract Retinoic acid exhibits effects on the proliferation and differentiation of many hematopoietic cells. Cellular responsiveness to retinoic acid (RA) is conferred through two distinct classes of nuclear receptors, the RA receptors (RARs) and the retinoid X receptors (RXRs). The RARs bind to both 9-cis- and all-trans-RAs, but 9-cis-RA alone directly binds and activates RXR. This suggested that 9-cis-RA could have expanded hematopoietic activities as compared with all-trans-RA. We compared the abilities of 9-cis- and all-trans-RAs to induce differentiation and inhibit proliferation of three acute myelogenous leukemia (AML) cell lines and fresh leukemic cells from 28 patients and found that: (1) 9-cis-RA in general was more potent than all-trans-RA in suppressing the clonal growth of two AML cell lines and 17 AML samples from patients, including four from individuals with acute promyelocytic leukemia (APL). Eleven leukemic samples, including three from patients with chronic myelogenous or chronic myelomonocytic leukemia, were relatively refractory to both retinoids. (2) The range of activities of both retinoids was similar except that the clonal growth of samples from three AML patients were inhibited by 9-cis-RA, but not by all-trans-RA. (3) Both retinoids inhibited the clonal proliferation of leukemia cells without necessarily inducing their differentiation; in fact, the only fresh AML cells that were able to undergo differentiation were from patients with APL and one individual with M2 AML. (4) Both retinoids enhanced myeloid and erythroid clonal growth from normal individuals, and 9-cis-RA showed slightly more stimulation of the myeloid clonal growth than did the all-trans-RA. Our study suggests that 9-cis-RA is worthy of further study for the treatment of selected individuals with AML.

scholarly journals Myeloid differentiation mediated through retinoic acid receptor/retinoic X receptor (RXR) not RXR/RXR pathway

Blood ◽  
1994 ◽  
Vol 84 (2) ◽  
pp. 446-452 ◽  
Author(s):  
MI Dawson ◽  
E Elstner ◽  
M Kizaki ◽  
DL Chen ◽  
S Pakkala ◽  
...  
Keyword(s):  
Retinoic Acid ◽  
Cell Lines ◽  
Clonal Growth ◽  
Synergistic Effects ◽  
Myeloid Cell ◽  
Leukemic Cell ◽  
Leukemic Cells ◽  
Cd11b Expression ◽  
Inhibition Of Proliferation

Abstract Retinoids, such as all-trans-retinoic acid and 9-cis-retinoic acid, are naturally occurring ligands of the nuclear retinoic acid receptors (RARs). In concert with binding of ligand, these receptors from heterodimers with the retinoic X receptor (RXR) and transactivate RAR/RXR-responsive genes. Retinoids can differentiate leukemic cell lines in vitro and induce clinically complete remissions in patients with acute promyelocytic leukemia. Synthetic ligands to the RAR and RXR receptors have been developed that selectively bind and activate RAR/RXR (TTAB) and RXR/RXR dimers (SR11217). We investigated the affect of these ligands, either alone or in combination, on in vitro growth and differentiation of cells from the HL-60, KG-1, THP-1, and WEHI-3 myeloid cell lines as well as on clonal growth of fresh myeloid leukemic blasts from patients. Clonal inhibition of proliferation of these cells was studied in soft agar cultures. Cells were plated in the presence of either one or a combination of retinoids at concentrations of 10(-5) to 10(-10) mol/L. TTAB inhibited 50% clonal growth at an effective dose (ED50) that was about 1,000-fold lower than the concentration of SR11217 required to achieve an ED50 for the same leukemic cells. Combination of both ligands at a variety of concentrations showed no synergistic effects. Superoxide production (nitroblue tetrazolium reduction) and CD11b expression as parameters of differentiation of HL-60 cells were also examined. Results paralleled those of clonal growth, with SR11217 being markedly less potent than TTAB. These results show that the ligand selective for RXR-homodimers has little effect on either inducing differentiation or inhibiting clonal growth of leukemic cells. The differentiating and antiproliferative effects of retinoids are mainly induced through RAR/RXR heterodimers, and development of therapeutic analogs should focus on this category of retinoids.

scholarly journals Myeloid differentiation mediated through retinoic acid receptor/retinoic X receptor (RXR) not RXR/RXR pathway

Blood ◽  
1994 ◽  
Vol 84 (2) ◽  
pp. 446-452
Author(s):  
MI Dawson ◽  
E Elstner ◽  
M Kizaki ◽  
DL Chen ◽  
S Pakkala ◽  
...  
Keyword(s):  
Retinoic Acid ◽  
Cell Lines ◽  
Clonal Growth ◽  
Synergistic Effects ◽  
Myeloid Cell ◽  
Leukemic Cell ◽  
Leukemic Cells ◽  
Cd11b Expression ◽  
Inhibition Of Proliferation

Retinoids, such as all-trans-retinoic acid and 9-cis-retinoic acid, are naturally occurring ligands of the nuclear retinoic acid receptors (RARs). In concert with binding of ligand, these receptors from heterodimers with the retinoic X receptor (RXR) and transactivate RAR/RXR-responsive genes. Retinoids can differentiate leukemic cell lines in vitro and induce clinically complete remissions in patients with acute promyelocytic leukemia. Synthetic ligands to the RAR and RXR receptors have been developed that selectively bind and activate RAR/RXR (TTAB) and RXR/RXR dimers (SR11217). We investigated the affect of these ligands, either alone or in combination, on in vitro growth and differentiation of cells from the HL-60, KG-1, THP-1, and WEHI-3 myeloid cell lines as well as on clonal growth of fresh myeloid leukemic blasts from patients. Clonal inhibition of proliferation of these cells was studied in soft agar cultures. Cells were plated in the presence of either one or a combination of retinoids at concentrations of 10(-5) to 10(-10) mol/L. TTAB inhibited 50% clonal growth at an effective dose (ED50) that was about 1,000-fold lower than the concentration of SR11217 required to achieve an ED50 for the same leukemic cells. Combination of both ligands at a variety of concentrations showed no synergistic effects. Superoxide production (nitroblue tetrazolium reduction) and CD11b expression as parameters of differentiation of HL-60 cells were also examined. Results paralleled those of clonal growth, with SR11217 being markedly less potent than TTAB. These results show that the ligand selective for RXR-homodimers has little effect on either inducing differentiation or inhibiting clonal growth of leukemic cells. The differentiating and antiproliferative effects of retinoids are mainly induced through RAR/RXR heterodimers, and development of therapeutic analogs should focus on this category of retinoids.

scholarly journals Effects of novel retinoid X receptor-selective ligands on myeloid leukemia differentiation and proliferation in vitro

Blood ◽  
1996 ◽  
Vol 87 (5) ◽  
pp. 1977-1984 ◽  
Author(s):  
M Kizaki ◽  
MI Dawson ◽  
R Heyman ◽  
E Elster ◽  
R Morosetti ◽  
...  
Keyword(s):  
Retinoic Acid ◽  
Clonal Growth ◽  
Myeloid Leukemia ◽  
Target Genes ◽  
Synergistic Effects ◽  
Leukemic Cells ◽  
Acute Myeloid Leukemia Cells ◽  
Differentiation And Proliferation ◽  
Acute Myeloid

The biologic effects of retinoids such as all-trans-retinoic acid (ATRA) and 9-cis-retinoic acid on proliferation and differentiation of hematopoietic cells are mediated by binding and activating two distinct families of transcription factors: the retinoic acid receptors (RARs) and the retinoid X receptors (RXRs). The RARs require heterodimerization with RXRs; in addition, RXRs can form homodimers, which can bind to DNA response elements that are either distinct or the same as those bound by the RAR/RXR heterodimers. Therefore, the two retinoid pathways provide sequences that are specific for effective DNA binding and activation of target genes. We have developed several series of novel synthetic retinoids that selectively interact with RXR/RXR homodimers and RAR/RXR heterodimers. We show here that SR11236 and SR11246, which are RXR-selective analogs, had little ability to inhibit clonal growth and induce differentiation of leukemic cells (HL- 60 cells and fresh acute myeloid leukemia cells). However, SR11249, SR11256, and LGD1069, which activated both RXR/RXR homodimers and RAR/RXR heterodimers, could inhibit clonal growth and induce differentiation of HL-60 cells as well as leukemic cells from patients, including those with acute promyelocytic leukemia (APL). This is similar to results observed with RAR/RXR-specific ligands. Interestingly, the combination of ATRA and either SR11249, SR11256, or LGD1069 showed synergistic effects in inducing differentiation of HL-60 cells. A retinoid (SR11238) with strong anti-AP-1 activity that did not activate the RARs and RXRs for gene transcription from the response element TREpal was inactive in our assay systems, suggesting that the antiproliferative effects of retinoids on leukemic cells is not mediated by inhibiting the AP-1 pathway. We conclude that the RAR/RXR pathway is more important than RXR/RXR pathway for differentiation and proliferation of acute myeloid leukemic cells, and certain retinoids or combination of retinoids with both RAR and RXR specificities may synergistically enhance the differentiation activity of ATRA, which may be relevant in several clinical situations.

scholarly journals cis-Retinoic acid stimulates the clonal growth of some myeloid leukemia cells in vitro

Blood ◽  
1987 ◽  
Vol 69 (1) ◽  
pp. 302-307 ◽  
Author(s):  
HJ Lawrence ◽  
K Conner ◽  
MA Kelly ◽  
MR Haussler ◽  
P Wallace ◽  
...  
Keyword(s):  
Retinoic Acid ◽  
T Lymphocytes ◽  
Clonal Growth ◽  
Colony Growth ◽  
Leukemic Cells ◽  
Leukemia Cells ◽  
Human Leukemia ◽  
Growth Responses ◽  
Drug Concentrations

Abstract We studied the effects of cis-retinoic acid (cisRA) on the clonogenic growth of samples of leukemic cells from 35 patients with acute nonlymphocytic leukemia (ANLL). We observed significant inhibition of leukemic colony growth in 17 samples by 10(-7) to 10(-6)M cisRA. However, we found that retinoid exposure resulted in striking stimulation of clonal growth in ten samples at the same drug concentrations. With the exception of cases with promyelocytic features, there was no morphologic or functional evidence that cisRA induced the leukemic blasts to differentiate. Both inhibition and stimulation were dose-dependent and observable at pharmacologically achievable levels of cisRA. Leukemic cells with monocytic features more frequently demonstrated a stimulatory response than did those without monocytic features. Depletion of T lymphocytes and monocytes did not alter the type of growth response. Assays for cellular retinoic acid- binding protein (CRABP) were performed on five samples (two with inhibitory growth responses, two with stimulatory responses, and one with no growth) and failed to reveal detectable levels of CRABP in any case. The addition of cisRA to liquid suspensions of leukemic cells produced no significant change in the number of viable cells. We conclude that the effects of cisRA on leukemic colony growth are not cytotoxic and not mediated by T lymphocytes, monocytes, or CRABP. More importantly, cisRA appears to enhance the growth of certain human leukemia cells in vitro. Taking into account the increasing use of retinoids in clinical trials for patients with leukemia, the latter findings may represent a significant cautionary note.

scholarly journals Effects of novel retinoid X receptor-selective ligands on myeloid leukemia differentiation and proliferation in vitro

Blood ◽  
1996 ◽  
Vol 87 (5) ◽  
pp. 1977-1984 ◽  
Author(s):  
M Kizaki ◽  
MI Dawson ◽  
R Heyman ◽  
E Elster ◽  
R Morosetti ◽  
...  
Keyword(s):  
Retinoic Acid ◽  
Clonal Growth ◽  
Myeloid Leukemia ◽  
Target Genes ◽  
Synergistic Effects ◽  
Leukemic Cells ◽  
Acute Myeloid Leukemia Cells ◽  
Differentiation And Proliferation ◽  
Acute Myeloid

Abstract The biologic effects of retinoids such as all-trans-retinoic acid (ATRA) and 9-cis-retinoic acid on proliferation and differentiation of hematopoietic cells are mediated by binding and activating two distinct families of transcription factors: the retinoic acid receptors (RARs) and the retinoid X receptors (RXRs). The RARs require heterodimerization with RXRs; in addition, RXRs can form homodimers, which can bind to DNA response elements that are either distinct or the same as those bound by the RAR/RXR heterodimers. Therefore, the two retinoid pathways provide sequences that are specific for effective DNA binding and activation of target genes. We have developed several series of novel synthetic retinoids that selectively interact with RXR/RXR homodimers and RAR/RXR heterodimers. We show here that SR11236 and SR11246, which are RXR-selective analogs, had little ability to inhibit clonal growth and induce differentiation of leukemic cells (HL- 60 cells and fresh acute myeloid leukemia cells). However, SR11249, SR11256, and LGD1069, which activated both RXR/RXR homodimers and RAR/RXR heterodimers, could inhibit clonal growth and induce differentiation of HL-60 cells as well as leukemic cells from patients, including those with acute promyelocytic leukemia (APL). This is similar to results observed with RAR/RXR-specific ligands. Interestingly, the combination of ATRA and either SR11249, SR11256, or LGD1069 showed synergistic effects in inducing differentiation of HL-60 cells. A retinoid (SR11238) with strong anti-AP-1 activity that did not activate the RARs and RXRs for gene transcription from the response element TREpal was inactive in our assay systems, suggesting that the antiproliferative effects of retinoids on leukemic cells is not mediated by inhibiting the AP-1 pathway. We conclude that the RAR/RXR pathway is more important than RXR/RXR pathway for differentiation and proliferation of acute myeloid leukemic cells, and certain retinoids or combination of retinoids with both RAR and RXR specificities may synergistically enhance the differentiation activity of ATRA, which may be relevant in several clinical situations.

Chlorogenic acid inhibits Bcr-Abl tyrosine kinase and triggers p38 mitogen-activated protein kinase–dependent apoptosis in chronic myelogenous leukemic cells

Blood ◽  
2004 ◽  
Vol 104 (8) ◽  
pp. 2514-2522 ◽  
Author(s):  
Gautam Bandyopadhyay ◽  
Tanusree Biswas ◽  
Keshab C. Roy ◽  
Swapan Mandal ◽  
Chhabinath Mandal ◽  
...  
Keyword(s):  
Chlorogenic Acid ◽  
Cell Lines ◽  
Salivary Gland Tumor ◽  
K562 Cells ◽  
Myelogenous Leukemia ◽  
Mitogen Activated Protein Kinase ◽  
Leukemic Cells ◽  
Abl Kinase ◽  
Mitogen Activated Protein

Abstract We report that chlorogenic acid (Chl) induces apoptosis of several Bcr-Abl–positive chronic myelogenous leukemia (CML) cell lines and primary cells from CML patients in vitro and destroys Bcr-Abl–positive K562 cells in vivo. In contrast, this compound has no effect on the growth and viability of Bcr-Abl–negative lymphocytic and myeloid cell lines and primary CML cells. Sodium chlorogenate (NaChl) exhibits 2-fold higher efficiency in killing K562 cells compared with Chl. NaChl also induces growth inhibition of squamous cell carcinoma (HSC-2) and salivary gland tumor cells (HSG), although at 50-fold higher concentration. NaChl inhibits autophosphorylation of p210Bcr-Abl fusion protein rapidly. We demonstrate that p38 phosphorylation is increased in Bcr-Abl–positive cells after treatment with NaChl and closely paralleled the inhibition of Bcr-Abl phosphorylation. NaChl did not increase phosphorylation of p38 in Bcr-Abl–negative cells including HSC-2 and HSG that are responsive to this compound, indicating that p38 activation by NaChl is dependent on Bcr-Abl kinase inhibition. Inhibition of p38 activity by SB203580 significantly reduced NaChl-induced apoptosis of K562 cells, whereas activation of p38 by anisomycin augmented the apoptosis. These findings indicate that inhibition of Bcr-Abl kinase leading to activation of p38 mitogen-activated protein (MAP) kinase may play an important role in the anti-CML activity of Chl.

scholarly journals cis-Retinoic acid stimulates the clonal growth of some myeloid leukemia cells in vitro

Blood ◽  
1987 ◽  
Vol 69 (1) ◽  
pp. 302-307
Author(s):  
HJ Lawrence ◽  
K Conner ◽  
MA Kelly ◽  
MR Haussler ◽  
P Wallace ◽  
...  
Keyword(s):  
Retinoic Acid ◽  
T Lymphocytes ◽  
Clonal Growth ◽  
Colony Growth ◽  
Leukemic Cells ◽  
Leukemia Cells ◽  
Human Leukemia ◽  
Growth Responses ◽  
Drug Concentrations

We studied the effects of cis-retinoic acid (cisRA) on the clonogenic growth of samples of leukemic cells from 35 patients with acute nonlymphocytic leukemia (ANLL). We observed significant inhibition of leukemic colony growth in 17 samples by 10(-7) to 10(-6)M cisRA. However, we found that retinoid exposure resulted in striking stimulation of clonal growth in ten samples at the same drug concentrations. With the exception of cases with promyelocytic features, there was no morphologic or functional evidence that cisRA induced the leukemic blasts to differentiate. Both inhibition and stimulation were dose-dependent and observable at pharmacologically achievable levels of cisRA. Leukemic cells with monocytic features more frequently demonstrated a stimulatory response than did those without monocytic features. Depletion of T lymphocytes and monocytes did not alter the type of growth response. Assays for cellular retinoic acid- binding protein (CRABP) were performed on five samples (two with inhibitory growth responses, two with stimulatory responses, and one with no growth) and failed to reveal detectable levels of CRABP in any case. The addition of cisRA to liquid suspensions of leukemic cells produced no significant change in the number of viable cells. We conclude that the effects of cisRA on leukemic colony growth are not cytotoxic and not mediated by T lymphocytes, monocytes, or CRABP. More importantly, cisRA appears to enhance the growth of certain human leukemia cells in vitro. Taking into account the increasing use of retinoids in clinical trials for patients with leukemia, the latter findings may represent a significant cautionary note.

Effects of Novel RAR- and RXR-Selective Retinoids on Myeloid Leukemic Proliferation and Differentiation In Vitro

Blood ◽  
1999 ◽  
Vol 93 (6) ◽  
pp. 2057-2066 ◽  
Author(s):  
Masaaki Shiohara ◽  
Marcia I. Dawson ◽  
Peter D. Hobbs ◽  
Nobukuni Sawai ◽  
Tsukasa Higuchi ◽  
...  
Keyword(s):  
Retinoic Acid ◽  
Clonal Growth ◽  
Leukemic Cell ◽  
Leukemic Cells ◽  
Cd11b Expression ◽  
Nb4 Cells ◽  
Continuous Contact ◽  
Proliferation And Differentiation ◽  
Factor C

Retinoids such as all-trans-retinoic acid (ATRA) and 9-cis-retinoic acid (9-cis-RA) have an important role in many aspects of proliferation and differentiation of hematopoietic cells. They exert their effects by binding to retinoic acid receptors (RARs) and/or retinoid X receptors (RXRs). We studied the effects of novel retinoids on proliferation and differentiation of HL-60 and NB4 myeloid leukemic cells, as well as acute promyelocytic leukemia (APL) cells from patients. RXR-selective SR11345 (Retinoid C) had little ability to inhibit the clonal growth and to induce the differentiation of either HL-60 or NB4 cells. However, SR11276 (Retinoid E), which activated both the RAR and RXR classes, and SR11278 (Retinoid D), which activated the RAR subtypes , β, and γ, could inhibit clonal growth of both cell types, as well as leukemic cells from APL patients. The combination of ATRA and either SR11276 or SR11278 additively inhibited APL cell proliferation. SR11302 (Retinoid A), with reported anti-AP–1 activity and no activation of RARs and RXR and SR11363 (Retinoid B), which selectively activated RARβ and γ, were inactive. The clonal proliferation of both HL-60 and NB4 cells that were pulse-exposed to 10-9 mol/L ATRA, SR11276, SR11278, or SR11345 for 3 days, washed, and plated in methylcellulose culture were inhibited by 0%, 51%, 21%, and 1% for HL-60 cells and 43%, 41%, 35%, and 1% for NB4, respectively, compared with nontreated control cells. When the HL-60 cells were pulse-exposed to 10-9 mol/L of either SR11278 or SR11276, plus 10-9 mol/L ATRA for 3 days, colony numbers were reduced by 46% and 64%, respectively. Induction of leukemic cell differentiation as determined by the nitroblue tetrazolium (NBT) assay showed that the combination of 10-7 mol/L of either SR11278 or SR11276 with 10-7 mol/L ATRA had additive effects on HL-60 cells, NB4 cells, and fresh APL cells. Induction of CD11b expression on both HL-60 and NB4 cells occurs during their differentiation. Expression of this antigen was synergistically augmented by the combination of either 10-7 to 10-8 mol/L SR11278 or 10-7to 10-9 mol/L SR11276 with 10-9 mol/L ATRA compared with either analog alone in HL-60 cells. Expression of the novel myeloid specific transcription factor C/EBPɛ was increased by SR11278 and SR11276 in both the HL-60 and NB4 cell lines. We conclude that retinoids or combination of retinoids with specificities for both RAR and RXR may markedly enhance the ability of ATRA to inhibit clonal growth and induce differentiation of HL-60 and NB4 leukemic cells. This occurs in the absence of continuous contact with retinoids.

Synthesis and Characterization of New Palladium(II) Complexes with Ligands Derived from Furan-2-carbaldehyde and Benzaldehyde Thiosemicarbazone and their in vitro Cytotoxic Activities against Various Human Tumor Cell Lines

2010 ◽  
Vol 65 (10) ◽  
pp. 1271-1278 ◽  
Author(s):  
Wilfredo Hernández ◽  
Juan Paz ◽  
Fernando Carrasco ◽  
Abraham Vaisberg ◽  
Jorge Manzur ◽  
...  
Keyword(s):  
Tumor Cell ◽  
Cell Lines ◽  
Human Tumor ◽  
Myelogenous Leukemia ◽  
Cytotoxic Activities ◽  
Spectroscopic Techniques ◽  
Tumor Cell Lines ◽  
Human Tumor Cell ◽  
Human Tumor Cell Lines

With the ligands 4-phenyl-1-(furan-2-carbaldehyde)thiosemicarbazone, HTSC1, (1), 4-phenyl-1- (5´-phenyl-furan-2-carbaldehyde)thiosemicarbazone, HTSC2 (2), o-methoxy-benzaldehydethiosemicarbazone, HTSC3 (3), and o-cyano-benzaldehydethiosemicarbazone, HTSC4 (4), the corresponding palladium(II) complexes, Pd(TSC1)2 (5), Pd(TSC2)2 (6), Pd(TSC3)2 (7), and Pd(TSC4)2 (8) were synthesized and characterized by elemental analysis and spectroscopic techniques. The crystal structure of Pd(TSC3)2 (7) was determined by single-crystal X-ray diffraction. Complex 7 shows a squareplanar geometry, where two deprotonated ligands are coordinated to the PdII center through the nitrogen and sulfur atoms in a trans arrangement. In vitro antitumor studies against different human tumor cell lines have revealed that the palladium(II) complexes 5- 8 are more cytotoxic (IC50 values in the range of 0.21 - 3.79 μM) than their corresponding ligands (1 - 4) (> 60 μM). These results indicate that the antiproliferative activity is enhanced when thiosemicarbazone ligands are coordinated to the metal. Among the studied palladium(II) complexes, 8 exhibits high antitumor activity on K562 chronic myelogenous leukemia cells with a low value of the inhibitory concentration (IC50 = 0.21 μM).

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