Highly malignant triple-negative breast cancer (TNBC) cells rely mostly on glycolysis to maintain cellular homeostasis; however, mitochondria are still required for migration and metastasis. Taking advantage of the metabolic flexibility of TNBC MDA-MB-231 cells to generate subpopulations with glycolytic or oxidative phenotypes, we screened phenolic compounds containing an ortho-carbonyl group with mitochondrial activity and identified a bromoalkyl-ester of hydroquinone named FR58P1a, as a mitochondrial metabolism-affecting compound that uncouples OXPHOS through a protonophoric mechanism. In contrast to well-known protonophore uncoupler FCCP, FR58P1a does not depolarize the plasma membrane and its effect on the mitochondrial membrane potential and bioenergetics is moderate suggesting a mild uncoupling of OXPHOS. FR58P1a activates AMPK in a Sirt1-dependent fashion. Although the activation of Sirt1/AMPK axis by FR58P1a has a cyto-protective role, selectively inhibits fibronectin-dependent adhesion and migration in TNBC cells but not in non-tumoral MCF10A cells by decreasing β1-integrin at the cell surface. Prolonged exposure to FR58P1a triggers a metabolic reprograming in TNBC cells characterized by down-regulation of OXPHOS-related genes that promote cell survival but comprise their ability to migrate. Taken together, our results show that TNBC cell migration is susceptible to mitochondrial alterations induced by small molecules as FR58P1a, which may have therapeutic implications.

A great number of alkaloids exhibit high potential in cancer research. Some of them are anticancer drugs with well-defined clinical uses, exerting their action on microtubules dynamics or DNA replication and topology. On the other hand, mitochondria have been recognized as an essential organelle in the establishment of tumor characteristics, especially the resistance to cell death, high proliferative capacity and adaptation to unfavorable cellular environment. Interestingly, many alkaloids exert their anticancer activities affecting selectively some functions of the tumor mitochondria by 1) modulating OXPHOS and ADP/ATP transport, 2) increasing ROS levels and mitochondrial potential dissipation by crosstalk between endoplasmic reticulum (ER) and mitochondria, 3) inducing mitochondria-dependent apoptosis and autophagy, 4) inhibiting mitochondrial metabolic pathways and 5) by alteration of the morphology and biogenesis of this organelle. These antecedents show the relevance of developing research about the effects of alkaloids on functions controlled by tumor mitochondria, offering an attractive target for the design of new alkaloid derivatives, considering organelle- specific delivery strategies. This review describes mitochondria as a central component in the anticancer action of a set of alkaloids, in a way to illustrate the importance of this organelle in medicinal chemistry.

Reprimo-like (RPRML) is an uncharacterized member of the Reprimo gene family. Here, we evaluated the role of RPRML and whether its regulation by DNA methylation is a potential non-invasive biomarker of gastric cancer. RPRML expression was evaluated by immunohistochemistry in 90 patients with gastric cancer and associated with clinicopathologic characteristics and outcomes. The role of RPRML in cancer biology was investigated in vitro, through RPRML ectopic overexpression. Functional experiments included colony formation, soft agar, MTS, and Ki67 immunofluorescence assays. DNA methylation-mediated silencing was evaluated by the 5-azacytidine assay and direct bisulfite sequencing. Non-invasive detection of circulating methylated RPRML DNA was assessed in 25 gastric cancer cases and 25 age- and sex-balanced cancer-free controls by the MethyLight assay. Downregulation of RPRML protein expression was associated with poor overall survival in advanced gastric cancer. RPRML overexpression significantly inhibited clonogenic capacity, anchorage-independent growth, and proliferation in vitro. Circulating methylated RPRML DNA distinguished patients with gastric cancer from controls with an area under the curve of 0.726. The in vitro overexpression results and the poor patient survival associated with lower RPRML levels suggest that RPRML plays a tumor-suppressive role in the stomach. Circulating methylated RPRML DNA may serve as a biomarker for the non-invasive detection of gastric cancer.

Recently, the combination of chemotherapy plus nivolumab (chemo-immunotherapy) has become the standard of care for advanced-stage gastric cancer (GC) patients. However, despite its efficacy, up to 40% of patients do not respond to these treatments. Our study sought to identify variations in gene expression associated with primary resistance to chemo-immunotherapy. Diagnostic endoscopic biopsies were retrospectively obtained from advanced GC patients previously categorized as responders (R) or non-responders (NR). Thirty-four tumor biopsies (R: n = 16, NR: n = 18) were analyzed by 3′ massive analysis of cDNA ends (3′MACE). We found >30 differentially expressed genes between R and NRs. Subsequent pathway enrichment analyses demonstrated that angiogenesis and the Wnt-β-catenin signaling pathway were enriched in NRs. Concomitantly, we performed next generation sequencing (NGS) analyses in a subset of four NR patients that confirmed alterations in genes that belonged to the Wnt/β-catenin and the phosphoinositide 3-kinase (PI3K) pathways. We speculate that angiogenesis, the Wnt, and the PI3K pathways might offer actionable targets. We also discuss therapeutic alternatives for chemo-immunotherapy-resistant advanced-stage GC patients.