Pan-EGFR Inhibitor Dacomitinib Resensitizes Paclitaxel and Induces Apoptosis via Elevating Intracellular ROS Levels in Ovarian Cancer SKOV3-TR Cells.

Paclitaxel is still used as a standard first-line treatment for ovarian cancer. Although paclitaxel is effective for many types of cancer, the emergence of chemoresistant cells represents a major challenge in chemotherapy. Our study aimed to analyze the cellular mechanism of dacomitinib, a pan-epidermal growth factor receptor (EGFR) inhibitor, which resensitized paclitaxel and induced cell cytotoxicity in paclitaxel-resistant ovarian cancer SKOV3-TR cells. We investigated the significant reduction in cell viability cotreated with dacomitinib and paclitaxel by WST-1 assay and flow cytometry analysis. Dacomitinib inhibited EGFR family proteins, including EGFR and HER2, as well as its downstream signaling proteins, including AKT, STAT3, ERK, and p38. In addition, dacomitinib inhibited the phosphorylation of Bad, and combination treatment with paclitaxel effectively suppressed the expression of Mcl-1. A 2'-7'-dichlorodihydrofluorescein diacetate (DCFH-DA) assay revealed a substantial elevation in cellular reactive oxygen species (ROS) levels in SKOV3-TR cells cotreated with dacomitinib and paclitaxel, which subsequently mediated cell cytotoxicity. Additionally, we confirmed that dacomitinib inhibits chemoresistance in paclitaxel-resistant ovarian cancer HeyA8-MDR cells. Collectively, our research indicated that dacomitinib effectively resensitized paclitaxel in SKOV3-TR cells by inhibiting EGFR signaling and elevating intracellular ROS levels.

Deguelin Restores Paclitaxel Sensitivity in Paclitaxel-Resistant Ovarian Cancer Cells via Inhibition of the EGFR Signaling Pathway.

Background: Ovarian cancer is one of women's malignancies with the highest mortality among gynecological cancers. Paclitaxel is used in first-line ovarian cancer chemotherapy. Research on paclitaxel-resistant ovarian cancer holds significant clinical importance. Methods: Cell viability and flow cytometric assays were conducted at different time and concentration points of deguelin and paclitaxel treatment. Immunoblotting was performed to assess the activation status of key signaling molecules important for cell survival and proliferation following treatment with deguelin and paclitaxel. The fluo-3 acetoxymethyl assay for P-glycoprotein transport activity assay and cell viability assay in the presence of N-acetyl-L-cysteine were also conducted. Results: Cell viability and flow cytometric assays demonstrated that deguelin resensitized paclitaxel in a dose- and time-dependent manner. Cotreatment with deguelin and paclitaxel inhibited EGFR and its downstream signaling molecules, including AKT, ERK, STAT3, and p38 MAPK, in SKOV3-TR cells. Interestingly, cotreatment with deguelin and paclitaxel suppressed the expression level of EGFR via the lysosomal degradation pathway. Cotreatment did not affect the expression and function of P-glycoprotein. N-acetyl-L-cysteine failed to restore cell cytotoxicity when used in combination with deguelin and paclitaxel in SKOV3-TR cells. The expression of BCL-2, MCL-1, and the phosphorylation of the S155 residue of BAD were downregulated. Moreover, inhibition of paclitaxel resistance by deguelin was also observed in HeyA8-MDR cells. Conclusion: Our research showed that deguelin effectively suppresses paclitaxel resistance in SKOV3-TR ovarian cancer cells by downregulating the EGFR and its downstream signaling pathway and modulating the BCL-2 family proteins. Furthermore, deguelin exhibits inhibitory effects on paclitaxel resistance in HeyA8-MDR ovarian cancer cells, suggesting a potential mechanism for paclitaxel resensitization that may not be cell-specific. These findings suggest that deguelin holds promise as an anticancer therapeutic agent for overcoming chemoresistance in ovarian cancer.

Phloroglucinol Enhances Anagen Signaling and Alleviates H2O2-Induced Oxidative Stress in Human Dermal Papilla Cells.

Phloroglucinol (PG) is one of the abundant isomeric benzenetriols in brown algae. Due to its polyphenolic structure, PG exhibits various biological activities. However, the impact of PG on anagen signaling and oxidative stress in human dermal papilla cells (HDPCs) is unknown. In this study, we investigated the therapeutic potential of PG for improving hair loss. A non-cytotoxic concentration of PG increased anagen-inductive genes and transcriptional activities of ß-Catenin. Since several anagen-inductive genes are regulated by ß-Catenin, further experiments were performed to elucidate the molecular mechanism by which PG upregulates anagen signaling. Various biochemical analyses revealed that PG upregulated ß-Catenin signaling without affecting the expression of Wnt. In particular, PG elevated the phosphorylation of protein kinase B (AKT), leading to an increase in the inhibitory phosphorylation of glycogen synthase kinase 3 beta (GSK3ß) at serine 9. Treatment with the selective phosphoinositide 3-kinase/AKT inhibitor, LY294002, restored the increased AKT/GSK3ß/ß-Catenin signaling and anagen-inductive proteins induced by PG. Moreover, conditioned medium from PG-treated HDPCs promoted the proliferation and migration of human epidermal keratinocytes via the AKT signaling pathway. Subsequently, we assessed the antioxidant activities of PG. PG ameliorated the elevated oxidative stress markers and improved the decreased anagen signaling in hydrogen peroxide (H2O2)-induced HDPCs. The senescence-associated ß-galactosidase staining assay also demonstrated that the antioxidant abilities of PG effectively mitigated H2O2-induced senescence. Overall, these results indicate that PG potentially enhances anagen signaling and improves oxidative stress-induced cellular damage in HDPCs. Therefore, PG can be employed as a novel therapeutic component to ameliorate hair loss symptoms.

Effects of Nonylphenol on the Secretion of Catecholamines and Adrenocortical Hormones from Short-Term Incubated Rat Adrenal Glands.

Previously, we showed that a chronic-low-dose nonylphenol (NP) exposure resulted in histological changes with sexually dimorphic pattern in rat adrenal glands. We hypothesized that such structural changes are closely related to the hormonal secretory patterns. To test this hypothesis, we developed the short-term adrenal incubation method, and measured the levels of catecholamines and cortical steroids using the high-performance liquid chromatography with electrochemical detection (HPLC-ECD) and specific enzyme-linked immunosorbent assay, respectively. The norepinephrine (NE) levels in media from NP-treated female adrenal, except 100 pM NP, were significantly increased [control (CTL) vs 1 nM NP, p<0.001; vs 10 nM NP, p<0.05; vs 100 nM NP, p<0.001; vs 1 µM NP, p<0.01]. The NE secretion from male adrenal was higher when treated with 100 nM and 1 µM NP (CTL vs 100 nM NP, p<0.05; vs 1 µM NP, p<0.05, respectively). The aldosterone level in the female adrenal media treated with 100 pM NP was significantly decreased, on the other hand, that of media treated with 10 nM NP was significantly increased (CTL vs 100 pM NP, p<0.05; vs 10 nM NP, p<0.01). In male adrenal media, the aldosterone levels of 10 nM, 100 nM and 1 µM NP-treated media were significantly declined (CTL vs 10 nM NP, p<0.001; vs 100 nM NP, p<0.001; vs 1 µM NP, p<0.001). These results showed the NP treatment altered secretory pattern of aldosterone from adrenals of both sexes, showing sexual dimorphism. It may be helpful for understanding possible adrenal pathophysiology, and endocrine disrupting chemicals-related sexually dimorphic phenomena in adrenals.

Tephrosin Suppresses the Chemoresistance of Paclitaxel-Resistant Ovarian Cancer via Inhibition of FGFR1 Signaling Pathway.

Ovarian cancer is the leading cause of death among gynecologic cancers. Paclitaxel is used as a standard first-line therapeutic agent for ovarian cancer. However, chemotherapeutic resistance and high recurrence rates are major obstacles to treating ovarian cancer. We have found that tephrosin, a natural rotenoid isoflavonoid, can resensitize paclitaxel-resistant ovarian cancer cells to paclitaxel. Cell viability, immunoblotting, and a flow cytometric analysis showed that a combination treatment made up of paclitaxel and tephrosin induced apoptotic death. Tephrosin inhibited the phosphorylation of AKT, STAT3, ERK, and p38 MAPK, all of which simultaneously play important roles in survival signaling pathways. Notably, tephrosin downregulated the phosphorylation of FGFR1 and its specific adapter protein FRS2, but it had no effect on the phosphorylation of the EGFR. Immunoblotting and a fluo-3 acetoxymethyl assay showed that tephrosin did not affect the expression or function of P-glycoprotein. Additionally, treatment with N-acetylcysteine did not restore cell cytotoxicity caused by a treatment combination made up of paclitaxel and tephrosin, showing that tephrosin did not affect the reactive oxygen species scavenging pathway. Interestingly, tephrosin reduced the expression of the anti-apoptotic factor XIAP. This study demonstrates that tephrosin is a potent antitumor agent that can be used in the treatment of paclitaxel-resistant ovarian cancer via the inhibition of the FGFR1 signaling pathway.