Norcantharidin combined with paclitaxel induces endoplasmic reticulum stress mediated apoptotic effect in prostate cancer cells by targeting SIRT7 expression

Paclitaxel and docetaxel resistance in prostate cancer: Molecular mechanisms and possible therapeutic strategies

Prostate cancer is among most malignant tumors around the world and this urological tumor can be developed as result of genomic mutations and their accumulation during progression towards advanced stage. Due to lack of specific symptoms in early stages of prostate cancer, most cancer patients are diagnosed in advanced stages that tumor cells display low response to chemotherapy. Furthermore, genomic mutations in prostate cancer enhance the aggressiveness of tumor cells. Docetaxel and paclitaxel are suggested as well-known compounds for chemotherapy of prostate tumor and they possess a similar function in cancer therapy that is based on inhibiting depolymerization of microtubules, impairing balance of microtubules and subsequent delay in cell cycle progression. The aim of current review is to highlight mechanisms of paclitaxel and docetaxel resistance in prostate cancer. When oncogenic factors such as CD133 display upregulation and PTEN as tumor-suppressor shows decrease in expression, malignancy of prostate tumor cells enhances and they can induce drug resistance. Furthermore, phytochemicals as anti-tumor compounds have been utilized in suppressing chemoresistance in prostate cancer. Naringenin and lovastatin are among the anti-tumor compounds that have been used for impairing progression of prostate tumor and enhancing drug sensitivity. Moreover, nanostructures such as polymeric micelles and nanobubbles have been utilized in delivery of anti-tumor compounds and decreasing risk of chemoresistance development. These subjects are highlighted in current review to provide new insight for reversing drug resistance in prostate cancer.

Sirtuins and their influence on autophagy

Sirtuins and autophagy are well-characterized agents that can promote longevity and protect individual organisms from age-associated diseases like neurodegenerative disorders. In recent years, more and more data has been obtained that discerned potential overlaps and crosstalk between Sirtuin proteins and autophagic activity. This review aims to summarize the advances within the field for each individual Sirtuin in mammalian systems. In brief, most Sirtuins have been implicated in promoting autophagy, with Sirtuin 1 and Sirtuin 6 showing the highest immediate involvement, while Sirtuin 4 and Sirtuin 5 only demonstrate occasional influence. The way Sirtuins regulate autophagy, however, is very diverse, as they have been shown to regulate gene expression of autophagy-associated genes and posttranslational modifications of proteins, with consequences for the activity and cellular localization of these proteins. They have also been shown to determine specific proteins for autophagic degradation. Overall, much data has been accumulated over recent years, yet many open questions remain. Especially although the dynamic between Sirtuin proteins and the immediate regulation of autophagic players like Light Chain 3B has been confirmed, many of these proteins have various orthologues in mammalian systems, and research so far has not exceeded the bona fide components of autophagy.

LncRNA RHPN1-AS1 inhibition induces autophagy and apoptosis in prostate cancer cells via the miR-7-5p/EGFR/PI3K/AKT/mTOR signaling pathway

LncRNA RHPN1-AS1 (RHPN1-AS1) has been confirmed to promote tumor progression in multiple cancers and is upregulated in prostate cancer (PCa), but whether it has an effect on PCa progression remains unclear. In this study, we found that PCa patients with high RHPN1-AS1 expression had a shorter survival time, and RHPN1-AS1 was significantly upregulated in PCa tissues and cells. Based on informatics analysis we predicted that miR-7-5p binds to 3'UTR of RHPN1-AS1 and epidermal growth factor receptor (EGFR) and verified it by luciferase reporter gene assay. Subsequently, we transfected PCa cells with RHPN1-AS1 overexpression vector (RHPN1-AS1), knockdown plasmids (sh-RHPN1-AS1) and/or miR-7-5p mimics or inhibitor and/or overexpression vector (EGFR) or small interfering RNA of EGFR (si-EGFR) or its control, and found that overexpression of RHPN1-AS1 inhibited miR-7-5p expression and promoted EGFR expression, silencing RHPN1-AS1 inhibited proliferation and invasion, and induced G2/M arrest, apoptosis and autophagy in PCa cells. 3MA (an inhibitor of autophagy)-mediated autophagy inhibition attenuated RHPN1-AS1 inhibition-induced apoptosis. Overexpression miR-7-5p or silencing EGFR promoted LC3-I to LC3-II conversion, enhanced autophagy activity, induced cleaved-caspase-3 expression and apoptosis in PCa cells. Furthermore, overexpression of RHPN1-AS1 promoted phosphorylation of phosphatidylinositol 3-kinase (PI3K), AKT and mTOR, inhibited LC3-I to LC3-II conversion and reduced apoptosis in PCa cells, while GSK2126458 (an inhibitor of PI3K) reversed the effect of RHPN1-AS1 on PCa cells. In summary, RHPN1-AS1 acted as a ceRNA of miR-7-5p to upregulate EGFR expression, silencing RHPN1-AS1 suppressed PCa tumor progression by inducing autophagy and apoptosis in PCa cells through the miR-7-5p/EGFR/PI3K/AKT/mTOR pathway.

The endoplasmic reticulum stress response in prostate cancer

In order to proliferate in unfavourable conditions, cancer cells can take advantage of the naturally occurring endoplasmic reticulum-associated unfolded protein response (UPR) via three highly conserved signalling arms: IRE1α, PERK and ATF6. All three arms of the UPR have key roles in every step of tumour progression: from cancer initiation to tumour growth, invasion, metastasis and resistance to therapy. At present, no cure for metastatic prostate cancer exists, as targeting the androgen receptor eventually results in treatment resistance. New research has uncovered an important role for the UPR in prostate cancer tumorigenesis and crosstalk between the UPR and androgen receptor signalling pathways. With an improved understanding of the mechanisms by which cancer cells exploit the endoplasmic reticulum stress response, targetable points of vulnerability can be uncovered.

Norbornene and Related Structures as Scaffolds in the Search for New Cancer Treatments

The norbornene scaffold has arisen as a promising structure in medicinal chemistry due to its possible therapeutic application in cancer treatment. The development of norbornene-based derivatives as potential chemotherapeutic agents is attracting significant attention. Here, we report an unprecedented review on the recent advances of investigations into the antitumoral efficacy of different compounds, including the abovementioned bicyclic scaffold in their structure, in combination with chemotherapeutic agents or forming metal complexes. The impact that structural modifications to these bicyclic compounds have on the antitumoral properties and the mechanisms by which these norbornene derivatives act are discussed in this review. In addition, the use of norbornene, and its related compounds, encapsulation in nanosystems for its use in cancer therapies is here detailed.

Norcantharidin induces ferroptosis via the suppression of NRF2/HO‑1 signaling in ovarian cancer cells

Increasing evidence has indicated a crucial role of ferroptosis in ovarian cancer (OC). Norcantharidin (NCTD), a normethyl compound of cantharidin, is extensively used in clinical practice as an optional anticancer drug. However, whether NCTD leads to ferroptosis in OC has not been previously explored, at least to the best of our knowledge. In the present study, the effect of NCTD on SKOV3 and OVCAR-3 cells was evaluated. The experimental data of the present study revealed that NCTD significantly suppressed SKOV3 and OVCAR-3 cell viability in a concentration- and time-dependent manner. The results of Cell Counting Kit-8 assay revealed that NCTD treatment decreased SKOV3 and OVCAR-3 cell viability. In comparison, pre-incubation with ferrostatin-1 (Fer-1) significantly reversed the NCTD-induced reduction in SKOV3 and OVCAR-3 cell viability; however, no changes in cell viability were observed when the SKOV3 and OVCAR-3 cells were treated with NCTD, in combination with the apoptosis inhibitor, Z-VAD-FMK, the ferroptosis inhibitor, necrostatin-1, and the autophagy inhibitor, 3-methyladenine. Additionally, it was observed that NCTD markedly enhanced reactive oxygen species production and malondialdehyde and ferrous ion levels in the SKOV3 and OVCAR-3 cells; however, pre-incubation with Fer-1 abolished these effects. Flow cytometry also demonstrated a significant increase in cell death following treatment of the SKOV3 and OVCAR-3 cells with NCTD; however, pre-incubation with Fer-1 also reversed these effects. In vivo experiments demonstrated that NCTD significantly reduced tumor volume and weight. More importantly, it was revealed that nuclear factor erythroid 2-related factor 2 (NRF2), heme oxygenase 1 (HO-1), glutathione peroxidase 4 (GPX4) and solute carrier family 7 member 11 (xCT) expression levels were significantly decreased following NCTD treatment. Collectively, NCTD may represent a potent anticancer agent in OC cells, and NCTD-induced ferroptotic cell death may be achieved by inhibiting the NRF2/HO-1/GPX4/xCT axis.

Sirtuin 7 serves as a promising therapeutic target for cardiorenal diseases

Cardiovascular disorders and associated renal diseases account for the main cause of morbidity and mortality worldwide, necessitating the development of novel effective approaches for the prevention and treatment of cardiorenal diseases. Mammalian sirtuins (SIRTs) function as nicotinamide adenine dinucleotide (NAD+)-dependent protein/histone deacetylases. Seven members of SIRTs share a highly invariant catalytic core domain responsible for the specific enzymatic activity. Intriguingly, the broad distribution of SIRTs and alternative isoforms implicate its distinct functions in diverse cardiac and renal cells and tissue types. Notably, SIRT7 has been shown to exert beneficial effects in cardiorenal physiology and pathophysiology via modulation of senescence, DNA damage repair, ribosomal RNA synthesis, protein biosynthesis, angiogenesis, apoptosis, superoxide generation, cardiorenal metabolism, and dysfunction. Furthermore, SIRT7 has emerged as a critical modulator of a broad range of cellular activities including oxidative stress, inflammation response, endoplasmic reticulum stress, and mitochondrial homeostasis, which are all of great significance in postponing the progression of cardiorenal diseases. More importantly, SIRT7 has been implicated in cardiorenal hypertrophy, fibrosis, remodeling, heart failure, atherosclerosis as well as renal acid-base and electrolyte homeostasis as an essential regulator. In this review, we focus on the involvement in cardiorenal physiology and pathophysiology, diverse actions and underlying mechanisms of the SIRT7 signaling, highlighting its updated research progress in heart failure, atherosclerosis, diabetic nephropathy and other cardiorenal diseases. Targeting SIRT7 signaling could be potentially exploited as a therapeutic strategy aiming to prevent and treat cardiorenal diseases.