Linking unfolded protein response to ovarian cancer cell fusion

Background

Polyploid giant cancer cells (PGCCs) have been observed in epithelial ovarian tumors. They can resist antimitotic drugs, thus participating in tumor maintenance and recurrence. Although their origin remains unclear, PGCC formation seems to be enhanced by conditions that trigger the unfolded protein response (UPR) such as hypoxia or chemotherapeutic drugs like paclitaxel. Hypoxia has been shown to promote the formation of ovarian PGCCs by cell fusion. We thus hypothesized that the UPR could be involved in EOC cell fusion, possibly explaining the occurrence of PGCCs and the aggressiveness of EOC.

Methods

The UPR was induced in two ovarian cancer cell lines (SKOV3 and COV318). The UPR activation was assessed by Western blot and polyploidy indexes were calculated. Then, to confirm the implication of cell fusion in PGCC formation, two populations of SKOV3 cells were transfected with plasmids encoding for two distinct nuclear fluorescent proteins (GFP and mCherry) associated with different antibiotic resistance genes, and the two cell populations were mixed in co-culture. The co-culture was submitted to a double-antibiotic selection. The resulting cell population was characterized for its morphology, cyclicity, and proliferative and tumorigenic capacities, in addition to transcriptomic characterization.

Results

We demonstrated that cell fusion could be involved in the generation of ovarian PGCCs and this process was promoted by paclitaxel and the UPR activation. Double-antibiotic treatment of PGCCs led to the selection of a pure population of cells containing both GFP- and mCherry-positive nuclei. Interestingly, after 3 weeks of selection, we observed that these cells were no longer polynucleated but displayed a single nucleus positive for both fluorescent proteins, suggesting that genetic material mixing had occurred. These cells had reinitiated their normal cell cycles, acquired an increased invasive capacity, and could form ovarian tumors in ovo.

Conclusions

The UPR activation increased the in vitro formation of PGCCs by cell fusion, with the newly generated cells further acquiring new properties. The UPR modulation in ovarian cancer patients could represent an interesting therapeutic strategy to avoid the formation of PGCCs and therefore limit cancer relapse and drug resistance.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09648-4.

Dual effect of nifedipine on pregnant human myometrium contractility: Implication of TRPC1

Nifedipine, an L‐type voltage‐gated Ca²⁺ channel (L‐VGCC) blocker, is one of the most used tocolytics to treat preterm labor. In clinical practice, nifedipine efficiently decreases uterine contractions, but its efficacy is limited over time, and repeated or maintained nifedipine‐based tocolysis appears to be ineffective in preventing preterm birth. We aimed to understand why nifedipine has short‐lasting efficiency for the inhibition of uterine contractions. We used ex vivo term pregnant human myometrial strips treated with cumulative doses of nifedipine. We observed that nifedipine inhibited spontaneous myometrial contractions in tissues with high and regular spontaneous contractions. By contrast, nifedipine appeared to increase contractions in tissues with low and/or irregular spontaneous contractions. To investigate the molecular mechanisms activated by nifedipine in myometrial cells, we used the pregnant human myometrial cell line PHM1‐41 that does not express L‐VGCC. The in vitro measurement of intracellular Ca²⁺ showed that high doses of nifedipine induced an important intracellular Ca²⁺ entry in myometrial cells. The inhibition or downregulation of the genes encoding for store‐operated Ca²⁺ entry channels from the Orai and transient receptor potential‐canonical (TRPC) families in PHM1‐41 cells highlighted the implication of TRPC1 in nifedipine‐induced Ca²⁺ entry. In addition, the use of 2‐APB in combination with nifedipine on human myometrial strips tends to confirm that the pro‐contractile effect induced by nifedipine on myometrial tissues may involve the activation of TRPC channels.

Role of the Uteroplacental Renin-Angiotensin System in Placental Development and Function, and Its Implication in the Preeclampsia Pathogenesis

Placental development and function implicate important morphological and physiological adaptations to thereby ensure efficient maternal–fetal exchanges, as well as pregnancy-specific hormone secretion and immune modulation. Incorrect placental development can lead to severe pregnancy disorders, such as preeclampsia (PE), which endangers both the mother and the infant. The implication of the systemic renin–angiotensin system (RAS) in the pregnancy-related physiological changes is now well established. However, despite the fact that the local uteroplacental RAS has been described for several decades, its role in placental development and function seems to have been underestimated. In this review, we provide an overview of the multiple roles of the uteroplacental RAS in several cellular processes of placental development, its implication in the regulation of placental function during pregnancy, and the consequences of its dysregulation in PE pathogenesis.

PLGA Nanoparticles for the Intraperitoneal Administration of CBD in the Treatment of Ovarian Cancer: In Vitro and In Ovo Assessment

The intraperitoneal administration of chemotherapeutics has emerged as a potential route in ovarian cancer treatment. Nanoparticles as carriers for these agents could be interesting by increasing the retention of chemotherapeutics within the peritoneal cavity. Moreover, nanoparticles could be internalised by cancer cells and let the drug release near the biological target, which could increase the anticancer efficacy. Cannabidiol (CBD), the main nonpsychotropic cannabinoid, appears as a potential anticancer drug. The aim of this work was to develop polymer nanoparticles as CBD carriers capable of being internalised by ovarian cancer cells. The drug-loaded nanoparticles (CBD-NPs) exhibited a spherical shape, a particle size around 240 nm and a negative zeta potential (-16.6 ± 1.2 mV). The encapsulation efficiency was high, with values above 95%. A controlled CBD release for 96 h was achieved. Nanoparticle internalisation in SKOV-3 epithelial ovarian cancer cells mainly occurred between 2 and 4 h of incubation. CBD antiproliferative activity in ovarian cancer cells was preserved after encapsulation. In fact, CBD-NPs showed a lower IC₅₀ values than CBD in solution. Both CBD in solution and CBD-NPs induced the expression of PARP, indicating the onset of apoptosis. In SKOV-3-derived tumours formed in the chick embryo model, a slightly higher-although not statistically significant-tumour growth inhibition was observed with CBD-NPs compared to CBD in solution. To sum up, poly-lactic-co-glycolic acid (PLGA) nanoparticles could be a good strategy to deliver CBD intraperitoneally for ovarian cancer treatment.

Effect of local aromatase inhibition in endometriosis using a new chick embryo chorioallantoic membrane model

Endometriosis is an oestrogen‐dependent, inflammation‐driven gynaecologic disorder causing severe disability. Endometriosis implants are characterized by unbalanced local oestrogen metabolism leading to hyperoestrogenism and aromatase up‐regulation is one of main mechanism involved. Aromatase inhibitors such as letrozole or anastrozole use in young women are associated with severely side effects limiting their long‐term clinical use. An endometriosis‐targeted inhibition of local aromatase could be a viable alternative, although the role of the local inhibition of this enzyme is still unclear. Using a new chick embryo allantoic membrane (CAM) model incorporating xenografted human endometriosis cyst, we showed that topical treatment with anastrozole reduced lesion size, although oestrogens produced by CAM female embryo blunted this effect. Xenografted human endometriosis CAM is a new efficient model for the screening of new drugs targeting endometriosis tissue.

Endoplasmic reticulum stress responses in placentation - A true balancing act

The unfolded protein response (UPR) is recognized as a key mechanism to promote protein folding and processing in eukaryotes when endoplasmic reticulum stress (ERS) occurs. Some conditions such as hypoxia or glucose deprivation are factors that may elicit ERS response. Recent literature collectively proposes that ERS response is crucial for mammalian reproduction by allowing decidualization and placentation to occur. However, prolonged ERS and activation of UPR pathways can lead to apoptosis and autophagy, which in turn could pose adverse effects on pregnancy outcomes and placentation. ERS associated pregnancy pathologies include intrauterine growth restriction and early-onset preeclampsia. Given these findings, evidence suggests that overactivation of UPR may lead to harmful reproductive circumstances, whereas physiological regulation of ERS response is essential for mammalian reproduction and placental function. In this review, we discuss the dual role of UPR activation with respect to its contribution to placental development as well as pathologies caused by pathway overactivation. In addition, we suggest potential protein markers associated with the UPR, as circulating C-terminal GRP78 or anti-GRP78 autoantibodies which may prove to be of clinical interest.

Changes in mammary secretory tissue during lactation in ovariectomized dairy cows

In dairy animals, the milk yield (MY) changes during a lactation and is influenced by several physiological, livestock management and environmental factors. The MY produced by a mammary gland depends on synthetic activity of mammary epithelial cells (MECs) as well as MEC number and mammary secretory tissue organization. It has been suggested that ovarian steroids (estradiol and progesterone) have a negative effect on MY in lactating cows. In a previous study, we showed that the suppression of ovarian secretions by an ovariectomy improved lactation persistency in dairy cows. Here we were interested in the effects of ovariectomy on plasma estradiol and progesterone concentrations and on changes that occur in mammary secretory tissue during lactation. We demonstrated that the ovariectomy of lactating cows at the time of the lactation peak induced a rapid and dramatic drop in plasma progesterone and a smaller reduction in plasma estradiol. Interestingly, the study of the changes in mammary secretory tissue over time revealed that the improvement of MY measured in the ovariectomized cows was associated with a limited increase in estradiol receptivity in MECs, a reduced mammary tissue remodeling and reduced blood protein concentration in milk, in late lactation. These results suggest that ovarian secretions, particularly estradiol and progesterone, act to enhance processes for mammary gland involution in late-lactating dairy cows.