The anti-tumor activity of pralatrexate (PDX) correlates with the expression of RFC and DHFR mRNA in preclinical models of multiple myeloma

Kinahan, Cristina; Mangone, Michael; Scotto, Luigi; Visentin, Michele; Marchi, Enrica; Cho, Hearn Jay; O’Connor, Owen A.

doi:10.18632/oncotarget.27516

Cited by 7 publications

(7 citation statements)

References 49 publications

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“…Using classical methods to produce drug-resistant cell lines, we generated two cell lines that showed approximately 30-fold greater resistance to PDX than their parental counterparts. The characteristics of the PDXresistant cells were as follows: (i) decreased internalization of PDX in CEM/P cells owing to reduced RFC expression; (ii) increased expression of DNMT3B; (iii) The potential mechanisms of acquired PDX resistance have gradually been uncovered in recent years [24,28,29], and appear to be similar to the resistance mechanism of MTX which have been extensively studied [30,31]. The most frequent mechanism mediating antifolate resistance is related to the impairment of antifolate uptake, typically due to reduced expression of RFC1 and/or inactivating mutations in RFC1 [21,22,28,32].…”

Section: Discussionmentioning

confidence: 99%

“…The characteristics of the PDXresistant cells were as follows: (i) decreased internalization of PDX in CEM/P cells owing to reduced RFC expression; (ii) increased expression of DNMT3B; (iii) The potential mechanisms of acquired PDX resistance have gradually been uncovered in recent years [24,28,29], and appear to be similar to the resistance mechanism of MTX which have been extensively studied [30,31]. The most frequent mechanism mediating antifolate resistance is related to the impairment of antifolate uptake, typically due to reduced expression of RFC1 and/or inactivating mutations in RFC1 [21,22,28,32]. Increased antifolate efflux owing to overexpression of multidrug resistance efflux transporters has also been reported [30,31].…”

Section: Discussionmentioning

confidence: 99%

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Characterization of newly established Pralatrexate-resistant cell lines and the mechanisms of resistance

et al. 2021

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Background Pralatrexate (PDX) is a novel antifolate approved for the treatment of patients with relapsed/refractory peripheral T-cell lymphoma, but some patients exhibit intrinsic resistance or develop acquired resistance. Here, we evaluated the mechanisms underlying acquired resistance to PDX and explored potential therapeutic strategies to overcome PDX resistance. Methods To investigate PDX resistance, we established two PDX-resistant T-lymphoblastic leukemia cell lines (CEM and MOLT4) through continuous exposure to increasing doses of PDX. The resistance mechanisms were evaluated by measuring PDX uptake, apoptosis induction and folate metabolism-related protein expression. We also applied gene expression analysis and methylation profiling to identify the mechanisms of resistance. We then explored rational drug combinations using a spheroid (3D)-culture assay. Results Compared with their parental cells, PDX-resistant cells exhibited a 30-fold increase in half-maximal inhibitory concentration values. Induction of apoptosis by PDX was significantly decreased in both PDX-resistant cell lines. Intracellular uptake of [14C]-PDX decreased in PDX-resistant CEM cells but not in PDX-resistant MOLT4 cells. There was no significant change in expression of dihydrofolate reductase (DHFR) or folylpolyglutamate synthetase (FPGS). Gene expression array analysis revealed that DNA-methyltransferase 3β (DNMT3B) expression was significantly elevated in both cell lines. Gene set enrichment analysis revealed that adipogenesis and mTORC1 signaling pathways were commonly upregulated in both resistant cell lines. Moreover, CpG island hypermethylation was observed in both PDX resistant cells lines. In the 3D-culture assay, decitabine (DAC) plus PDX showed synergistic effects in PDX-resistant cell lines compared with parental lines. Conclusions The resistance mechanisms of PDX were associated with reduced cellular uptake of PDX and/or overexpression of DNMT3B. Epigenetic alterations were also considered to play a role in the resistance mechanism. The combination of DAC and PDX exhibited synergistic activity, and thus, this approach might improve the clinical efficacy of PDX.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Characterization of newly established Pralatrexate-resistant cell lines and the mechanisms of resistance

et al. 2021

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“…Earlier data also show a similarly high sensitivity of DLBCL for PLX ( Marchi et al, 2010 ). The efficacy of PLX was shown to be related to the expression of RFC and DHFR ( Kinahan et al, 2020 ). This is in line with the findings that PLX is an excellent substrate for the RFC ( Figure 1 ; Wang et al, 2003 ; Visentin et al, 2014 ), but a poor substrate for PCFT and had a very low affinity for the folate receptors ( Table 1 ).…”

Section: Discussionmentioning

confidence: 99%

Schedule-Dependent Synergy Between the Histone Deacetylase Inhibitor Belinostat and the Dihydrofolate Reductase Inhibitor Pralatrexate in T-and B-cell Lymphoma Cells in vitro

Peters

Gemert

Kathmann

et al. 2020

Front. Cell Dev. Biol.

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Pralatrexate (Folotyn; PLX) and belinostat (Beleodaq; BLS) are registered for the treatment of patients with peripheral T-cell lymphoma (PTCL) and are being considered for other lymphomas. In this study we investigated whether BLS had the ability to potentiate the cytotoxicity of PLX. A panel of lymphoma cell lines was used for the combination studies: the B-cell SUDHL-4, SUDHL-5, HT, Jeko-1 and T-cell Karpas-299 and Hut-78. Uptake of PLX was mediated by the reduced folate carrier (RFC). PLX showed a 6-fold better RFC substrate affinity compared to methotrexate, and 2-fold better than levoleucovorin (l-LV). Sensitivity expressed as the concentration that resulted in 50% growth inhibition (IC50) after 72 hr exposure to PLX varied from 2.8 to 20 nM and for BLS from 72 to 233 nM, independent of the background of the cell lines. The interaction between BLS and PLX was studied using the median-drug effect analysis. At a fixed molar ratio between the drugs based on the IC50 concentration the average combination index (CI) for all cell lines showed additivity (CI: around 1.0). In three selected cell lines (SUDHL-4, SUDHL-5, and HT) sequential exposure (24 h pretreatment with BLS, followed by 48 h to PLX + BLS), did not improve interaction (CI: 0.9–1.4). As an alternative approach a non-fixed ratio was used by exposing SUDHL-4, SUDHL-5, and HT cells to IC25 concentrations of either BLS or PLX in combination with the other drug. Exposure to IC25 of PLX did not decrease the IC50 for BLS (CI from 0.6–1.2), but exposure to IC25 of BLS markedly increased PLX sensitivity (low CIs from 0.40 to 0.66). Mechanistic studies focused on induction of apoptosis, and showed cleavage of predominantly caspase-9 in HT and SUDHL-4 cells for both drugs at their IC50s, being similar in the combination setting. Moreover, at these concentrations, the drugs were shown to confer an S-phase arrest. In conclusion, the combination of PLX and BLS showed additivity in various lymphoma cell lines, with a schedule-dependent synergism in B-cell lymphoma. Based on these data, proficient inhibition of HDAC activity by BLS holds promise in sensitization of tumor cells to PLX.

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“…Point mutation of G at nucleotide 133 and the substitution of lysine to glutamic acid in the first transmembrane domain of the hRFC protein reduces the tendency of the drug methotrexate to bind the transporter in ALL patients. A decrease in RFC expression leads to methotrexate resistance and poor response to therapy in osteosarcoma and resistance to pralatrexate in multiple myeloma [77][78][79].…”

Section: Drug Influx and Effluxmentioning

confidence: 99%

Battling Chemoresistance in Cancer: Root Causes and Strategies to Uproot Them

Ramos

Sadeghi

Tabatabaeian

2021

IJMS

135

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With nearly 10 million deaths, cancer is the leading cause of mortality worldwide. Along with major key parameters that control cancer treatment management, such as diagnosis, resistance to the classical and new chemotherapeutic reagents continues to be a significant problem. Intrinsic or acquired chemoresistance leads to cancer recurrence in many cases that eventually causes failure in the successful treatment and death of cancer patients. Various determinants, including tumor heterogeneity and tumor microenvironment, could cause chemoresistance through a diverse range of mechanisms. In this review, we summarize the key determinants and the underlying mechanisms by which chemoresistance appears. We then describe which strategies have been implemented and studied to combat such a lethal phenomenon in the management of cancer treatment, with emphasis on the need to improve the early diagnosis of cancer complemented by combination therapy.

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The anti-tumor activity of pralatrexate (PDX) correlates with the expression of RFC and DHFR mRNA in preclinical models of multiple myeloma

Cited by 7 publications

References 49 publications

Characterization of newly established Pralatrexate-resistant cell lines and the mechanisms of resistance

Characterization of newly established Pralatrexate-resistant cell lines and the mechanisms of resistance

Schedule-Dependent Synergy Between the Histone Deacetylase Inhibitor Belinostat and the Dihydrofolate Reductase Inhibitor Pralatrexate in T-and B-cell Lymphoma Cells in vitro

Battling Chemoresistance in Cancer: Root Causes and Strategies to Uproot Them

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