Amino Acid Starvation Sensitizes Resistant Breast Cancer to Doxorubicin-Induced Cell Death

Circular RNAs as a novel molecular mechanism in diagnosis, prognosis, therapeutic target, and inhibiting chemoresistance in breast cancer

Breast cancer (BC) is the most common cancer among women, characterized by significant heterogeneity. Diagnosis of the disease in the early stages and appropriate treatment plays a crucial role for these patients. Despite the available treatments, many patients due to drug resistance do not receive proper treatments. Recently, circular RNAs (circRNAs), a type of non-coding RNAs (ncRNAs), have been discovered to be involved in the progression and resistance to drugs in BC. CircRNAs can promote or inhibit malignant cells by their function. Numerous circRNAs have been discovered to be involved in the proliferation, invasion, and migration of tumor cells, as well as the progression, pathogenesis, tumor metastasis, and drug resistance of BC. Circular RNAs can also serve as a biomarker for diagnosing, predicting prognosis, and targeting therapy. In this review, we present an outline of the variations in circRNAs expression in various BCs, the functional pathways, their impact on the condition, and their uses in clinical applications.

Cold atmospheric pressure plasma treatment combined with starvation increases autophagy and apoptosis in melanoma in vitro and in vivo

Despite advances in therapy, malignant melanoma remains a fatal disease. Among several emerging approaches to combat cancer, cold atmospheric pressure plasma (CAP) has shown promising results as a novel antitumor agent in preclinical models so far. The technology mainly relies on the emittance of various reactive oxygen and nitrogen species (ROS/RNS) that are tumor-toxic at high concentrations. Moreover, malignant melanoma has a metabolic dimension that can be targeted by mild starvation. To this end, we investigated the combined effect of starvation and CAP treatment on melanoma in vitro and in vivo. In vitro, starvation+CAP led to cell morphology changes, decreased metabolic activity and increased lipid peroxidation accompanied by apoptosis and DNA fragmentation in murine B16 melanoma cells but not murine non-malignant L929 fibroblasts. This was paralleled by increased apoptosis (Bax, Bcl-2 and Caspase-3) and autophagy (Lc3 and Atg5)-related gene expression. In vivo, starvation reduced tumor burden. Combination with CAP treatment augmented this effect significantly, albeit there was no difference of combination treatment to CAP exposure alone. Interestingly, there was an overall greater increase of Lc3 and Atg5 in the tumor tissue compared to CAP exposure alone, while starvation-induced autophagy-related gene expression was similar to in the combination group. These data collectively suggest that CAP-derived ROS/RNS treatment and autophagy-induction augment antitumor effects in malignant melanoma in vitro and in vivo.

Identification and validation of an epigenetically regulated long noncoding RNA model for breast cancer metabolism and prognosis

Background

Breast cancer (BC) is the leading cause of death among women, and epigenetic alterations that can dysregulate long noncoding RNAs (lncRNAs) are thought to be associated with cancer metabolism, development, and progression. This study investigated the epigenetic regulation of lncRNAs and its relationship with clinical outcomes and treatment responses in BC in order to identify novel and effective targets for BC treatment.

Methods

We comprehensively analysed DNA methylation and transcriptome data for BC and identified epigenetically regulated lncRNAs as potential prognostic biomarkers using machine learning and multivariate Cox regression analysis. Additionally, we applied multivariate Cox regression analysis adjusted for clinical characteristics and treatment responses to identify a set of survival-predictive lncRNAs, which were subsequently used for functional analysis of protein-encoding genes to identify downstream biological pathways.

Results

We identified a set of 1350 potential epigenetically regulated lncRNAs and generated a methylated lncRNA dataset for BC, MylnBrna, comprising 14 lncRNAs from a list of 20 epigenetically regulated lncRNAs significantly associated with tumour survival. MylnBrna stratifies patients into high-risk and low-risk groups with significantly different survival rates. These lncRNAs were found to be closely related to the biological pathways of amino acid metabolism and tumour metabolism, revealing a potential tumour-regulation function.

Conclusion

This study established a potential prognostic biomarker model (MylnBrna) for BC survival and offered an insight into the epigenetic regulatory mechanisms of lncRNAs in BC in the context of tumour metabolism.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-022-01256-2.

CircINTS4 Facilitates Chemoresistance of TNBC by Competitively Binding miR-129-5p/POM121 Axis

Objectives. To detect the expression of circular RNA (circRNA) circINTS4 in triple-negative breast cancer (TNBC) and to analyze the relationship between the expression of circRNA circINTS4 and the clinicopathological characteristics and chemotherapy resistance of patients with TNBC. Methods. Bioinformatics was used to predict that circINTS4 and POM121 could bind to miR-129-5p, and dual luciferase reporter genes proved that circINTS4 could bind to miR-129-5p and miR-129-5p could bind to POM121. RNA immunoprecipitation (RIP) and RNA pull-down experiments confirmed that circINTS4 binds to miR-129-5p. The correlation among circINTS4, miR-129-5p, and POM121 was detected by qRT-PCR. Results. In ADR-resistant TNB cells, circINTS4 was significantly up-regulated, miR-129-5p was down-regulated, and POM121 protein expression was significantly up-regulated. Experimental results showed that circINTS4 knockdown inhibited proliferation, migration, invasion, and autophagy. Knocking down miR-129-5p or overexpression of POM121 reversed the inhibitory effect of sh-circints4 on the development of ADR-resistant TNBC cells. In addition, CIRCINTS4 regulates POM121 expression by sponge-adsorbed miR-129-5p. CIRCINTS4 knockdown prevents ADR-resistant tumor growth by regulating the miR-129-5p/POM121 axis in vivo. Conclusions. CircRNA circINTS4 may act as the ceRNA of miR-129-5p to regulate the expression of target gene POM121, thereby promoting the progress of TNBC molecular mechanism and providing scientific basis for circINTS4 as a new molecular target for clinical diagnosis and drug resistance therapy of TNBC.

Synergistic Disruption of Metabolic Homeostasis through Hyperbranched Poly(ethylene glycol) Conjugates as Nanotherapeutics to Constrain Cancer Growth

Combination therapy is a promising approach for effective treatment of tumors through synergistically regulating pathways. However, the synergistic effect is limited, likely by uncontrolled co-delivery of different therapeutic payloads in a single nanoparticle. Herein, a combination nanotherapeutic is developed by using two amphiphilic conjugates, hyperbranched poly(ethylene glycol)-pyropheophorbide-a (Ppa) (HP-P) and hyperbranched poly(ethylene glycol)-doxorubicin (DOX) (HP-D) to construct co-assembly nanoparticles (HP-PD NPs) for controllably co-loading and co-delivering Ppa and DOX. In vitro and in vivo antitumor studies confirm the synergistic effect of photodynamic therapy and chemotherapy from HP-PD NPs. Metabolic variations reveal that tumor suppression is associated with disruption of metabolic homeostasis, leading to reduced protein translation. This study uncovers the manipulation of metabolic changes in tumor cells through disruption of cellular homeostasis using HP-PD NPs and provides a new insight into the rational design of synergistic nanotherapeutics for combination therapy.