Biochemistry

Purpose Multidrug resistance (MDR) is known as a problem limiting the success of therapy in patients treated long term with chemotherapeutic drugs. The drug resistance is mainly due to the overexpression of the 170 kDa P-glycoprotein (Pgp), which causes a reduction in drug accumulation in the cancer cells. In this study, novel chemical modulator(s) from bitter melon (Momordica charantia L.) extracts obtained from leaves, fruits and tendrils were tested for their abilities to modulate the function of Pgp and the MDR phenotype in the multidrug-resistant human cervical carcinoma KB-V1 cells (high Pgp expression) in comparison with wildtype drug-sensitive KB-3-1 cells (lacking Pgp). Methods The KB-V1 and KB-3-1 cells were exposed to bitter melon extracts in the presence of various concentrations of vinblastine, and cytotoxicity was assessed by means of the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay. Relative resistance was calculated as the ratio of the IC50 value of the KB-V1 cells to the IC50 value of the KB-3-1 cells. Accumulation and efflux of vinblastine in KB-V1 and KB-3-1 cells were measured using a [3H]-vinblastine incorporation assay. Results The leaf extracts increased the intracellular accumulation of [3H]-vinblastine in KB-V1 cells in a dose-dependent manner, but extracts from the fruits and tendrils had no effect. By modulating Pgp-mediated vinblastine efflux, the leaf extracts decreased the [3H]-vinblastine efflux in KB-V1 cells in a dose-dependent manner, but not in KB-3-1 cells. Treatment of drug-resistant KB-V1 cells with bitter melon leaf extracts increased their sensitivity to vinblastine, but similar treatment of KB-3-1 cells showed no modulating effect. The fruit and tendril extracts did not affect the MDR phenotype in either cell line. Conclusion The leaf extracts from bitter melon were able to reverse the MDR phenotype, which is consistent with an increase in intracellular accumulation of the drug. The exact nature of the active components of bitter melon leaf extracts remains to be identified.

Air pollution is one of the largest global environmental health hazards that threaten premature mortality or morbidity. Particulate matter 10 (PM10) has been demonstrated to contribute to several human diseases via dysregulated miRNA expression. Trophoblast cells play a key role in implantation and placentation for a successful pregnancy. Nonetheless, the PM10 associated trophoblast cell functions during pregnancy and miRNA expression are still unknown. Our study showed that PM10 affected HTR-8/SVneo cell viability and also decreased cell proliferation, migration, and invasion. A high concentration of PM10 caused an increase in HTR-8/SVneo cell apoptosis. Treatment with PM10 induced inflammation through the upregulated IL-1β, IL-6, and TNF-α expression in trophoblast cells. In PM10-treated HTR-8/SVneo cells, miR-125b-5p expression was considerably increased and TXNRD1 was found to be negatively related to miR-125b-5p. Collectively, our findings revealed that PM10 could alter miR-125...

Perilla leaves are known to be a rich source of polyphenols, which have been shown to exhibit various biological effects. This study aimed to compare the bioefficacies and bioactivities of fresh (PLEf) and dry (PLEd) Thai perilla (Nga-mon) leaf extracts. Phytochemical analysis indicated that both PLEf and PLEd were abundant in rosmarinic acid and bioactive phenolic compounds. PLEd, which had higher levels of rosmarinic acid but lower levels of ferulic acid and luteolin than PLEf, exhibited greater effectiveness in a free radical scavenging assay. Furthermore, both extracts were found to suppress intracellular ROS generation and exhibit antimutagenic activity against food-borne carcinogens in S. typhimurium. They also attenuated lipopolysaccharide-induced inflammation in RAW 264.7 cells by inhibiting the expression of nitric oxide, iNOS, COX-2, TNF-α, IL-1β, and IL-6 through the suppression of NF-κB activation and translocation. However, PLEf exhibited a higher ability to suppress ce...

Cancer cells evade replicative senescence by re-expressing telomerase, which maintains telomere length and hence chromosomal integrity. Telomerase inhibition would lead cancer cells to senesce and therefore prevent cancer cells from growing indefinitely. G-quadruplex ligands can attenuate telomerase activity by inducing G-quadruplex formation at the 3 0-overhang of telomere and at the human telomerase reverse transcriptase (hTERT) promoter; the former prevents telomerase from accessing the telomere, and the latter acts as a transcriptional silencer. The present investigation found that perylene derivatives PM2 and PIPER induced G-quadruplex formation from both telomeric DNA and the hTERT promoter region in vitro. Further, TRAP assay showed that these compounds inhibited telomerase in a dose-dependent manner. When A549 human lung cancer cells were treated with these compounds, hTERT expression was down-regulated. Moreover, the crude protein extract from these treated cells exhibited less telomerase activity. In the long-term treatment of A549 lung cancer cells with sub-cytotoxic dose of these perylenes, telomere shortening, reduction of cell proliferation and tumorigenicity, and cell senescence were observed. The results of this study indicate that perylene derivatives warrant further consideration as effective agents for cancer therapy.