One of the main problems in oncology is the development of drugs that cause the death of cancer cells without damaging normal cells. Another key problem to be solved is to suppress the drug resistance of cancer cells. The third important issue is to provide effective penetration of drug molecules to cancer cells. TRAIL (TNFα-related apoptosis inducing ligand)/Apo2L is a highly selective anticancer agent. However, the recombinant TRAIL protein having high efficiency against cancer cells in vitro was not effective in clinical trials. Recently we have discovered an acquisition of TRAIL resistance by cancer cells in confluent cultures, which is apparently a manifestation of the general phenomenon of multicellular resistance. The aim of this study was to evaluate whether the anticancer effect of the recombinant protein TRAIL in vivo can be improved by the suppression of multicellular TRAIL-resistance using sorafenib and a tumor-penetrating peptide iRGD, c(CRGDKGPDC). The results testified a great increase in the resistance of human fibrosarcoma HT-1080 cells to izTRAIL both in confluent cultures and in spheroids. Sorafenib administered at nontoxic concentration effectively suppressed confluent- or spheroid-mediated TRAIL-resistance of HT-1080 cells in vitro. Sorafenib combined with iRGD significantly improved the anticancer effect of the recombinant protein izTRAIL in HT-1080 human fibrosarcoma grafts in BALB/c nude mice. Consistent with this finding, multicellular TRAIL-resistance may be a reason of inefficacy of izTRAIL alone in vivo. The anticancer effect of the recombinant protein izTRAIL in vivo may be improved in combination with sorafenib, an inhibitor of multicellular TRAIL resistance and iRGD, the tumor-penetrating peptide.

Melatonin (N-acetyl-5-methoxytryptamine MEL) is an indolamine that has antioxidant, anti-inflammatory and anti-tumor properties. Moreover, MEL is capable of exhibiting both anti-apoptotic and pro-apoptotic effects. In the normal cells, MEL possesses antioxidant property and has an anti-apoptotic effect, while in the cancer cells it has pro-apoptotic action. We investigated the combined effect of MEL and navitoclax (ABT-737), which promotes cell death, on the activation of proliferation in acute promyelocytic leukemia on a cell model HL-60. The combined effect of these compounds leads to a reduction of the index of mitotic activity. The alterations in the level of anti- and pro-apoptotic proteins such as BclxL, Bclw, Mcl-1, and BAX, membrane potential, Ca2+ retention capacity, and ROS production under the combined action of MEL and ABT-737 were performed. We obtained that MEL in combination with ABT-737 decreased Ca2+ capacity, dropped membrane potential, increased ROS production, suppressed the expression of anti-apoptotic proteins such as BclxL, Bclw, and Mcl-1, and enhanced the expression of pro-apoptotic BAX. Since, MEL modulates autophagy and endoplasmic reticulum (ER) stress in cancer cells, the combined effect of MEL and ABT-737 on the expression of ER stress and autophagy markers was checked. The combined effect of MEL and ABT-737 (0.2 μM) increased the expression of protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK), leading to a decrease in the level of binding immunoglobulin protein (BIP) followed by an increase in the level of C/EBP homologous protein (CHOP). In this condition, the expression of ERO1 decreased, which could lead to a decrease in the level of protein disulfide isomerase (PDI). The obtained data suggested that melatonin has potential usefulness in the treatment of cancer, where it is able to modulate ER stress, autophagy and apoptosis.

Tailoring of the cytotoxicity and dissolution rate of luminescent porous silicon quantum dots is presented.

No abstract

Silicon nanoparticles (SiNP) are currently of great interest, especially in biomedicine, because of their unique physicochemical properties combined with biodegradability. SiNPs can be obtained in various ways and can have either a non-porous solid (sol-) or porous (por-) structure. In this work, we carry out detailed optical monitoring of sol- and por-SiNP biodegradation using Raman and photoluminescence (PL) micro-spectroscopy. SiNPs were obtained by ultrasound grinding of sol- or por-silicon nanowires, created by silver-assisted chemical etching of crystalline Si with different doping levels. In this case, sol-SiNPs consist of nanocrystals 30 nm in size, while por-SiNPs consist of small 3 nm nanocrystals and 16 nm pores. Both SiNPs show low in vitro cytotoxicity towards MCF-7 and HEK293T cells up to 800 μg/mL. The appearance of the F-band (blue–yellow) PL, as well as a decrease in the intensity of the Raman signal, indicate the gradual dissolution of the sol-SiNPs during 20 days of incubation. At the same time, the rapid dissolution of por-SiNP within 24 h is identified by the quenching of their S-band (red) PL and the disappearance of the Raman signal. The obtained results are important for development of intelligent biodegradable drug delivery systems based on SiNPs.

Recent demonstration that mechanism of action of small molecule imipridone ONC201 could be mediated through mitochondrial targeting (Graves et al., 2019; Greer et al., Ishizawa et al., 2019), was confirmed by identification of mitochondrial caseinolythic protease (ClpP), as the only target of ONC201 and its chemical analog TR57 (Graves et al., 2019). We further studied direct effect of these drugs on mitochondrial functions and mtDNA distribution in human breast cancer cells. Using respirometry and confocal microscopy, we demonstrated dose- and time dependent suppression of mitochondria oxygen consumption and degradation of mtDNA in cultured human BT-474 cell lines, treated with ONC201 and TR57. Both drugs, used in this study, induced significant and reversible decrease in the rate of proliferation as well as the content of mtDNA within the mitochondria (> by 50%), which was released into the cytosol. Semi-quantitative analysis of confocal images of mitochondrial matrix (MTDR, red fluorescence) and mtDNA (SYBR Green-1, green fluorescence) demonstrated 30-35% release of mtDNA from mitochondria/mitochondrial fragments. Exposure to ONC201 (10µM) or TR57 (50nM) for 48 h decreased mtDNA content by 60% and 85%, respectively. Effect of these drugs was reversible and washout of drugs restored the rate of proliferation as well as mtDNA content in time-dependent manner. Within 24h of washout, the total cellular mtDNA reached almost 90% of initial level, demonstrating fast activation of mtDNA synthesis upon removal of toxins. RT-PCR approach to monitor mtDNA in the cytosol and mitochondria confirmed release of mtDNA into the cytosol and associated decrease of mtDNA within mitochondria/mitochondrial fragments, following ONC201 or TR57 treatment of BT-474 cells. Taken together, our data demonstrate that these drugs reversibly modulate and regulate intracellular mtDNA content, through ONC201 and TR57 dependent regulation of mitochondrial biogenesis in human breast cancer cells. In conclusion, ONC201 & TR57 dependent reversible inhibition of cell proliferation and decrease in mtDNA content allow suggesting drug-dependent regulation of mitochondrial biogenesis in these BCC. Our observation warrants new direction in the elucidation of the mechanism of action of these drugs and search for novel efficient anti-cancer drugs. Support of Funding Information: Russian Science Foundation № 19-75-20145 Citation Format: Margarita I. Kobyakova, Serazhutdin Abdullaev, Yana V. Evstratova, Artem Mishukov, Irina Odinokova, Lee M. Graves, Ekhson Holmuhamedov. ONC201 & TR57 reversibly depletes mtDNA content & regulates mitochondrial biogenesis in BT-474, human breast cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 991.

The cytotoxicity and cytostatic effects of imipridone family drugs ONC201 and its analog TR57 (Madera, USA) in variety of cultured breast cancer cell line (estrogen dependent BT474) was manifested through induction of ISR (Integrated Stress Response), UPRER and UPRMT. The major consequences of drug treatment are inhibition of proliferation and mitochondrial structural and functional damage(s). Our preliminary data demonstrated that 24 h exposure of BT474 leads to dysregulation and suppression in mitochondrial Ca2+ uptake and Ca2+ capacity (Odinokova et al., 2021). In the present work, we extend our study to include the effect of these drugs on the rate of migration intact and treated cells in culture. Treatment of BT474 cells in culture for 24h resulted in decreased motility of cells from 17 ± 2 µm/h in the absence of the drugs to 5 ± 1 µm/h and to 3±1 µm/h in cells treated with 10µM of ONC201 or 50nM of TR57 (n=5). This suppression was fully reversible and removal of drugs for 120h resulted in time dependent restoration of the initial motility of BT474 cells, and TR57 caused larger inhibitory effect on motility as compared with ONC201. Buffering of extracellular Ca2+ with 5 mM EGTA or intracellular Ca2+ with 10 µM BAPTA, 30 min suppressed motility of cells (19 ± 2 µm/h vs 6 ± 1 µm/h). Gd3+, selective blocker of store operated Ca2+ entrance (SOCE) pathway at concentration of 10 µM suppressed the motility of BT474 cells, and rate of migration changed for from 16 ± 2 µm/h in control to 7± 2 µm/h, in Gd3+ treated cells. In line with our preliminary data, taken together these data indicate that ONC201 and/or TR57 induced dysfunction in mitochondrial Ca2+ homeostasis, which translates into the suppression of the migration of human breast cancer cells in culture. Support of Funding Information: Russian Science Foundation № 19-75-20145 Citation Format: Yana Evstratova, Margarita Kobyakova, Irina Odinokova, Alexander Stolyarov, Artyom Mishukov, Lee M. Graves, Ekhson Holmuhamedov. Reversible and dose-dependent suppression of motility of human breast cancer cells with ONC201 and/or TR57 in culture [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2888.