Apoptotic and autophagic cell death induced by glucolaxogenin in cervical cancer cells

Preparation and cytotoxic evaluation of new steroidal oximes and aza-homosteroids from diosgenin and cholesterol

Using cholesterol and diosgenin as starting materials, we have designed a straightforward methodology to prepare in a reduced number of steps a novel series of steroidal oximes and their aza-homolactam analogs with four types of side chains: cholestane, spirostane, 22-oxocholestane and 22,26-epoxycholestene. The products were evaluated for their cytotoxic activity against the MCF-7 breast cancer cell line. Moreover, the selectivity of the most active compounds was determined against peripheral blood lymphocytes. Compounds 5, 8 and 13 were found to be the most active derivatives, exhibiting IC₅₀ values in the low micromolar range (7.9-9.5 µM) and excellent selectivities (IC₅₀ > 100 µM) against the non-tumor cell line.

Synthesis and biological in vitro evaluation of the effect of hydroxyimino steroidal derivatives on breast cancer cells

Breast cancer is the most common cause of cancer death in women, according to Global Cancer Observatory. This fact forces scientists to continue in the search for effective treatments against this aggressive type of cancer. Breast cancer frequently metastasizes to other organs, most often the bones, lungs, and liver. Breast cancer is normally associated with estrogen and progestogen levels and can be hormone or non-hormone dependent. In current experiments herein reported, some hydroxyimino spirostan derivatives showed great potential against MCF-7 breast cancer, a Luminal-A cancer. On the other hand, a set of synthesized 6-hydroxyimino-22-oxocholestane compounds had excellent activity against the MDA-MB-231 breast cancer cell line. The synthesis of hydroxyamino derivatives from spirostan and 22-oxocholestane compounds was improved. The hydroxyimino compounds enhanced the bioactivity when compared with their parent carbonyl skeletons.

Saponins Extracted from Tea (Camellia Sinensis) Flowers Induces Autophagy in Ovarian Cancer Cells

Tea flower saponins (TFS) possess effective anticancer properties. The diversity and complexity of TFS increases the difficulty of their extraction and purification from tea flowers. Here, multiple methods including solvent extraction, microporous resin separation and preparative HPLC separation were used to obtain TFS with a yield of 0.34%. Furthermore, we revealed that TFS induced autophagy—as evidenced by an increase in MDC-positive cell populations and mCherry-LC3B-labeled autolysosomes and an upregulation of LC3II protein levels. 3-MA reversed the decrease in cell viability induced by TFS, showing that TFS induced autophagic cell death. TFS-induced autophagy was not dependent on the Akt/mTOR/p70S6K signaling pathway. TFS-induced autophagy in OVCAR-3 cells was accompanied by ERK pathway activation and reactive oxygen species (ROS) generation. This paper is the first report of TFS-mediated autophagy of ovarian cancer cells. These results provide new insights for future studies of the anti-cancer effects of TFS.

Regulation of autophagy by high- and low-risk human papillomaviruses

While high-risk human papillomavirus (HR-HPV) infection is related to the development of cervical, vulvar, anal, penile and oropharyngeal cancer, low-risk human papillomavirus (LR-HPV) infection is implicated in about 90% of genital warts, which rarely progress to cancer. The carcinogenic role of HR-HPV is due to the overexpression of HPV E5, E6 and E7 oncoproteins which target and modify cellular proteins implicated in cell proliferation, apoptosis and immortalization. LR-HPV proteins also target and modify some of these processes; however, their oncogenic potential is lower than that of HR-HPV. HR-HPVs have substantial differences with LR-HPVs such as viral integration into the cell genome, induction of p53 and retinoblastoma protein degradation, alternative splicing in HR-HPV E6-E7 open reading frames, among others. In addition, LR-HPV can activate the autophagy process in infected cells while HR-HPV infection deactivates it. However, in cancer HR-HPV might reactivate autophagy in advance stages. Autophagy is a catabolic process that maintains cell homoeostasis by lysosomal degradation and recycling of damaged macromolecules and organelles; nevertheless, depending upon cellular context autophagy may also induce cell death. Therefore, autophagy can contribute either as a promotor or as a suppressor of tumours. In this review, we focus on the role of HR-HPV and LR-HPV in autophagy during viral infection and cancer development. Additionally, we review key regulatory molecules such as microRNAs in HPV present during autophagy, and we emphasize the potential use of cancer treatments associated with autophagy in HPV-related cancers.

Apoptotic, necrotic, and antiproliferative activity of diosgenin and diosgenin glycosides on cervical cancer cells

(25R)-spirost-5-en-3β-ol, also known as diosgenin (DSG), exerts antiproliferative activity on diverse cell lines, induces apoptosis, and acts as a chemopreventative agent. However, the relationship between DSG glycosides and apoptotic, necrotic, and antiproliferative activity remains unclear. It is in this regard that we report the antiproliferative, necrotic, and apoptotic activities of DSG and its glycoside derivatives: (25R)-spirost-5-en-3β-yl O-β-D-glucopyranoside (3GD), (25R)-spirost-5-en-3β-yl O-α-L-rhamnopyranosyl-(1 → 4)-β-D-glucopyranoside (3GRD); and (25R)-spirost-5-en-3β-yl O-α-L-rhamnopyranosyl-(1 → 2)-O-[α-L-rhamnopyranosyl-(1 → 4)]-β-D-glucopyranoside), also known as dioscin (DSC), in in vitro assays of cervical HeLa and CaSki cancer cells. The results demonstrated that DSG glycosidic derivatives preserved their antiproliferative activity. However, in both cancer cell lines, 3GD and 3GRD were less potent than DSG, while DSC was more potent than DSG. With respect to necrotic activity, all tested compounds showed no or low activity on the two cervical cancer cell lines. Regarding apoptosis, the results showed that DSG glycosides were better apoptosis-inducers than DSG, suggesting that glucose and rhamnose residues play a central role in enhancing the apoptotic activity of DSG. Finally, DSG and its glycosidic derivatives were shown to affect the proliferative potential of lymphocytes (non-tumour cells) to a lesser extent than cancer cells, suggesting that these compounds have selective action. In conclusion, the results indicate that DSG and its glycosidic derivatives are promising anticancer compounds since they are compounds with low necrotic activity and selective action.

Wheat germ agglutinin-induced paraptosis-like cell death and protective autophagy is mediated by autophagy-linked FYVE inhibition

Wheat germ agglutinin (WGA) is a lectin that specifically binds cell surface glycoproteins and disrupts nuclear pore complex function through its interaction with POM121. Our data indicate WGA induces paraptosis-like cell death without caspase activation. We observed the main features of paraptosis, including cytoplasmic vacuolation, endoplasmic reticulum dilation and increased ER stress, and the unfolded protein response in WGA-treated cervical carcinoma cells. Conversion of microtubule-associated protein I light chain 3 (LC3-I) into LC3-II and punctuate formation suggestive of autophagy were observed in WGA-treated cells. WGA-induced autophagy antagonized paraptosis in HeLa and CaSKi cells, which expressed autophagy-linked FYVE (Alfy) protein, but not in SiHa cells that did not express Alfy. Alfy knockdown in HeLa cells induced paraptosis-like cell death. These data indicate that WGA-induced cell death occurs through paraptosis and that autophagy may exert a protective effect. WGA treatment and Alfy inhibition could be an effective therapeutic strategy for apoptosis-resistant cervical cancer cells.