YAP activation attenuates toxicarioside G‑induced lethal autophagy arrest in SW480 colorectal cancer cells

Toxicarioside H induces ferroptosis in triple-negative breast cancer cells through Nrf2/HO-1 pathway

Recent studies have identified novel cardiac glycosides from natural sources with potential anti-tumor properties. Toxicarioside H (ToxH) is a novel cardiac glycoside isolated by our collaborative research team. However, its ability to induce ferroptosis in triple-negative breast cancer (TNBC) cells has not been investigated. Therefore, this study evaluates whether ToxH has the capability of inducing ferroptosis and elucidates the underlying molecular mechanisms. Treatment with ToxH led to dose- and time-dependent growth inhibition in BT-549 and MDA-MB-468 cells. Flow cytometry analysis and lactate dehydrogenase assay revealed that ToxH induced various forms of cell death in both BT-549 and MDA-MB-468 cells. Examination through transmission electron microscopy, along with flow cytometry analysis of 7-AAD-stained dead cells and ferroptosis markers BODIPY-C11 and Fe2+ ions, identified various forms of cell death induced by ToxH, including apoptosis, autophagy, apoptotic necrosis, and ferroptosis. Co-treatment with the ferroptosis inhibitor Fer-1 significantly reduced ToxH-induced cell death, indicating that ToxH primarily inhibits TNBC cell growth by inducing ferroptosis. Further investigation into the molecular mechanisms revealed upregulation of Nrf2 and HO-1 expression by ToxH. Effective inhibition of ToxH-induced ferroptosis was achieved through shRNA-mediated knockdown of HO-1 expression. Animal experiments demonstrated that ToxH treatment markedly suppressed tumor growth compared to the control group, while co-administration of Fer-1 led to an increase in tumor growth. These findings suggest that ToxH suppresses TNBC cell growth by modulating the Nrf2/HO-1 signaling pathway to induce ferroptosis. ToxH presents itself as a promising cardiac glycoside compound for TNBC treatment, warranting further translational research.

Combination of ethyl acetate fraction from Calotropis gigantea stem bark and sorafenib induces apoptosis in HepG2 cells

The cytotoxicity of the ethyl acetate fraction of the Calotropis gigantea (L.) Dryand. (C. gigantea) stem bark extract (CGEtOAc) has been demonstrated in many types of cancers. This study examined the improved cancer therapeutic activity of sorafenib when combined with CGEtOAc in HepG2 cells. The cell viability and cell migration assays were applied in HepG2 cells treated with varying concentrations of CGEtOAc, sorafenib, and their combination. Flow cytometry was used to determine apoptosis, which corresponded with a decline in mitochondrial membrane potential and activation of DNA fragmentation. Reactive oxygen species (ROS) levels were assessed in combination with the expression of the phosphatidylinositol-3-kinase (PI3K)/ protein kinase B (Akt)/ mammalian target of rapamycin (mTOR) pathway, which was suggested for association with ROS-induced apoptosis. Combining CGEtOAc at 400 μg/mL with sorafenib at 4 μM, which were their respective half-IC50 concentrations, significantly inhibited HepG2 viability upon 24 h of exposure in comparison with the vehicle and each single treatment. Consequently, CGEtOAc when combined with sorafenib significantly diminished HepG2 migration and induced apoptosis through a mitochondrial-correlation mechanism. ROS production was speculated to be the primary mechanism of stimulating apoptosis in HepG2 cells after exposure to a combination of CGEtOAc and sorafenib, in association with PI3K/Akt/mTOR pathway suppression. Our results present valuable knowledge to support the development of anticancer regimens derived from the CGEtOAc with the chemotherapeutic agent sorafenib, both of which were administered at half-IC50, which may minimize the toxic implications of cancer treatments while improving the therapeutic effectiveness toward future medical applications.

Rational targeting of autophagy in colorectal cancer therapy: From molecular interactions to pharmacological compounds

The abnormal progression of tumors has been a problem for treatment of cancer and therapeutic should be directed towards targeting main mechanisms involved in tumorigenesis in tumors. The genomic mutations can result in changes in biological mechanisms in human cancers. Colorectal cancer is one of the most malignant tumors of gastrointestinal tract and its treatment has been faced some difficulties due to development of resistance in tumor cells and also, their malignant behavior. Hence, new therapeutic modalities for colorectal cancer are being investigated. Autophagy is a "self-digestion" mechanism that is responsible for homeostasis preserving in cells and its aberrant activation/inhibition can lead to tumorigenesis. The current review focuses on the role of autophagy mechanism in colorectal cancer. Autophagy may be associated with increase/decrease in progression of colorectal cancer due to mutual function of this molecular mechanism. Pro-survival autophagy inhibits apoptosis to increase proliferation and survival rate of colorectal tumor cells and it is also involved in cancer metastasis maybe due to EMT induction. In contrast, pro-death autophagy decreases growth and invasion of colorectal tumor cells. The status of autophagy (upregulation and down-regulation) is a determining factor for therapy response in colorectal tumor cells. Therefore, targeting autophagy can increase sensitivity of colorectal tumor cells to chemotherapy and radiotherapy. Interestingly, nanoparticles can be employed for targeting autophagy in cancer therapy and they can both induce/suppress autophagy in tumor cells. Furthermore, autophagy modulators can be embedded in nanostructures in improving tumor suppression and providing cancer immunotherapy.

Advances in understanding of role and mechanism of Hippo signaling pathway in colorectal cancer

Colorectal cancer (CRC) is one of the most common malignant tumors, and most patients have a poor prognosis. Many studies have shown that the Hippo signaling pathway plays a key role in the occurrence and development of CRC by regulating CRC cell proliferation and apoptosis, tumor invasion and metastasis, autophagy, metabolic reprogramming, drug resistance, and other processes. This article reviews the latest progress in research of the expression of key molecules of the Hippo signaling pathway in CRC as well as the understanding of the mechanism by which this pathway regulates the occurrence and development of CRC.

Forced Overexpression of Signal Transducer and Activator of Transcription 3 (STAT3) Activates Yes-Associated Protein (YAP) Expression and Increases the Invasion and Proliferation Abilities of Small Cell Lung Cancer (SCLC) Cells

Background: We sought to investigate the interaction between signal transducer and activator of transcription 3 (STAT3) and the Yes-associated protein (YAP) signaling pathway in human small cell lung cancer (SCLC) cells. Methods: The STAT3-overexpressing SCLC cell lines H146 and H446 were established by plasmid DNA transfection for in vitro and in vivo experiments. Results: Overexpression of STAT3 increased YAP protein expression in H146 and H446 cells. STAT3 overexpression significantly increased YAP mRNA expression and the mRNA expression of the YAP signaling downstream genes CTGF and CYR61 in H146 and H446 cells (p < 0.05). We showed that STAT3 overexpression promoted EMT (epithelial−mesenchymal transition) with increased matrix metalloproteinase (MMP)-2 and MMP9 expression. Transwell assays showed that STAT3 overexpression increased the invasion ability of H146 and H446 cells. In addition, STAT3-overexpressing H146 cells grew significantly more rapidly than control H146 cells in the xenograft mouse model (p < 0.05). Immunohistochemistry (IHC) staining and Western blotting (WB) showed that STAT3-overexpressing H146 tumors had increased p-STAT3 and YAP staining and protein expression compared with control tumors. Increased EMT was also observed in STAT3-overexpressed xenograft tumors. Conclusions: The results of our study suggest that the overexpression of STAT3 promotes SCLC EMT, invasion, and proliferation through the activation of the YAP signaling pathway.

Protective effect of methanol extract of latex of Calotropis procera in an experimental model of colorectal cancer

ETHNOPHARMACOLOGICAL RELEVANCE

The plant, Calotropis procera, has been used for treating various gastrointestinal disorders and cancer. Some of these medicinal properties have been attributed to the latex produced by the plant.

AIM OF THE STUDY

To evaluate the efficacy of methanol extract of air-dried latex (MeDL) of C. procera in the rat model of colorectal cancer (CRC).

MATERIALS AND METHODS

CRC was induced in the rats by 1,2-dimethylhydrazine (DMH) and the effect of MeDL was evaluated at two doses (50 and 150 mg/kg). MeDL and reference drug aspirin (60 mg/kg) were administered orally starting from 1 h before injecting DMH till 8 weeks after the second dose of DMH. The study also included experimental and normal control groups. Microscopic analysis was carried out to determine the count for aberrant crypt foci (ACF) and histology score whereas enzyme-linked immunosorbent assay and immunohistochemical analyses were performed for markers of carcinogenesis and angiogenesis. Other parameters that were evaluated include deoxyribonucleic acid (DNA) fragmentation, laddering, Bcl₂ and Bax immunoreactivity, and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) positivity.

RESULTS

Subcutaneous injection of DMH induced pre-neoplastic changes in the colon of rats with the appearance of ACF with multiple crypts (1-3, 4-6 or >6). In the experimental control group, total ACF count was 3.49 ± 0.23/cm of the colon length and the median histology score was 2.0 for architectural abnormalities, 2.0 for dilatation of crypts and 1.5 for hyperplasia/dysplasia against 1.0 for all the characteristics in normal rats. Oral administration of MeDL similar to aspirin, led to a reduction in ACF count and histology score of CRC concomitant with a decrease in the levels of markers of carcinogenesis - β-catenin and proliferating cell nuclear antigen (PCNA); markers of angiogenesis - matrix metallopeptidase-9 (MMP-9) and vascular endothelial growth factor (VEGF), and an increase in apoptotic DNA fragmentation.

CONCLUSION

MeDL confers protection in the rat model of CRC and the study suggests its therapeutic potential in this condition.