Abstract: Betulin is a pentacyclic triterpene found in many plant species, among others, in white birch bark. The aim of the study wasin vitrocharacterization of the anticancer activity of betulin in a range of human tumour cell lines (neuroblastoma, rhabdomyosarcoma‐medulloblastoma, glioma, thyroid, breast, lung and colon carcinoma, leukaemia and multiple myeloma), and in primary tumour cultures isolated from patients (ovarian carcinoma, cervical carcinoma and glioblastoma multiforme). In this study, we demonstrated a remarkable anti‐proliferative effect of betulin in all tested tumour cell cultures. Neuroblastoma (SK‐N‐AS) and colon carcinoma (HT‐29) were the most sensitive to the anti‐proliferative effect of betulin. Furthermore, betulin altered tumour cells morphology, decreased their motility and induced apoptotic cell death. These findings demonstrate the anti‐cancer potential of betulin and suggest that they may be applied as an adjunctive measure in cancer treatment.

Histone deacetylase inhibitors (HDIs) are promising anticancer drugs, which inhibit proliferation of a wide variety of cancer cells including breast carcinoma cells. In the present study, we investigated the influence of valproic acid (VPA) and suberoylanilide hydroxamic acid (SAHA, vorinostat), alone or in combination with cisplatin (CDDP) on proliferation, induction of apoptosis and cell cycle progression in MCF7, T47D and MDA-MB-231 human breast carcinoma cell lines. The type of interaction between HDIs and CDDP was determined by an isobolographic analysis. The isobolographic analysis is a very precise and rigorous pharmacodynamic method, to determine the presence of synergism, addition or antagonism between different drugs with using variety of fixed dose ratios. Our experiments show that the combinations of CDDP with SAHA or VPA at a fixed-ratio of 1:1 exerted additive interaction in the viability of MCF7 cells, while in T47D cells there was a tendency to synergy. In contrast, sub-additive (antagonistic) interaction was observed for the combination of CDDP with VPA in MDA-MB-231 “triple-negative” (i.e. estrogen receptor negative, progesterone receptor negative, and HER-2 negative) human breast cancer cells, whereas combination of CDDP with SAHA in the same MDA-MB-231 cell line yielded additive interaction. Additionally, combined HDIs/CDDP treatment resulted in increase in apoptosis and cell cycle arrest in all tested breast cancer cell lines in comparison with a single therapy. In conclusion, the additive interaction of CDDP with SAHA or VPA suggests that HDIs could be combined with CDDP in order to optimize treatment regimen in some human breast cancers.

Palmatine (PLT) is a natural isoquinoline alkaloid that belongs to the class of protoberberines and exhibits a wide spectrum of pharmacological and biological properties, including anti-cancer activity. The aim of our study was to isolate PLT from the roots of Berberis cretica and investigate its cytotoxic and anti-proliferative effects in vitro alone and in combination with doxorubicine (DOX) using human ER⁺/HER2⁻ breast cancer cell lines. The alkaloid was purified by column chromatography filled with silica gel NP and Sephadex LH-20 resin developed in the mixture of methanol: water (50:50 v/v) that provided high-purity alkaloid for bioactivity studies. The purity of the alkaloid was confirmed by high resolution mass measurement and MS/MS fragmentation analysis in the HPLC-ESI-QTOF-MS/MS-based analysis. It was found that PLT treatment inhibited the viability and proliferation of breast cancer cells in a dose-dependent manner as demonstrated by MTT and BrdU assays. PLT showed a quite similar growth inhibition on breast cancer cells with IC₅₀ values ranging from 5.126 to 5.805 µg/mL. In contrast, growth of normal human breast epithelial cells was not affected by PLT. The growth inhibitory activity of PLT was related to the induction of apoptosis, as determined by Annexin V/PI staining. Moreover, PLT sensitized breast cancer cells to DOX. Isobolographic analysis revealed synergistic and additive interactions between studied agents. Our studies suggest that PLT can be a potential candidate agent for preventing and treating breast cancer.

Inhibition of mitochondrial 2-oxoglutarate dehydrogenase impairs viability of cancer cells in a cell-specific metabolism-dependent manner

Gastric cancer (GC) has high incidence rates and constitutes a common cause of cancer mortality. Despite advances in treatment, GC remains a challenge in cancer therapy which is why novel treatment strategies are needed. The interest in natural compounds has increased significantly in recent years because of their numerous biological activities, including anti-cancer action. The isolation of the bioactive compounds from Coptis chinensis Franch was carried out with the Centrifugal Partition Chromatography (CPC) technique, using a biphasic solvent system composed of chloroform (CHCl₃)—methanol (MeOH)—water (H₂O) (4:3:3, v/v) with an addition of hydrochloric acid and trietylamine. The identity of the isolated alkaloids was confirmed using a high resolution HPLC-MS chromatograph. The phytochemical constituents of Coptis chinensis such as berberine, jatrorrhizine, palmatine and coptisine significantly inhibited the viability and growth of gastric cancer cell lines ACC-201 and NCI-N87 in a dose-dependent manner, with coptisine showing the highest efficacy as revealed using MTT and BrdU assays, respectively. Flow cytometry analysis confirmed the coptisine-induced population of gastric cancer cells in sub-G1 phase and apoptosis. The combination of coptisine with cisplatin at the fixed-ratio of 1:1 exerted synergistic and additive interactions in ACC-201 and NCI-N87, respectively, as determined by means of isobolographic analysis. In in vivo assay, coptisine was safe for developing zebrafish at the dose equivalent to the highest dose active in vitro, but higher doses (greater than 10 times) caused morphological abnormalities in larvae. Our findings provide a theoretical foundation to further studies on more detailed mechanisms of the bioactive compounds from Coptis chinensis Franch anti-cancer action that inhibit GC cell survival in in vitro settings.