Alejandra Paola García-Hernández

Umbelliferone (7-hydroxycoumarin) is a bioactive scaffold whose pharmacological profile may be modified through coordination to metal centers. Five coordination compounds of umbelliferone with the main-group elements Bi(III), In(III), Ga(III), Sb(III), and Te(IV) were synthesized by alkali-assisted deprotonation of the phenolic group followed by reaction with the corresponding metal salt, and characterized by melting point, FT-IR, ¹H and ¹³C NMR spectroscopy, FAB⁺ mass spectrometry, and elemental microanalysis. Disappearance of the phenolic ν(O–H) band (3113 cm⁻¹) and of the ¹H signal at 10.5 ppm in U-Bi, U-In, U-Ga and U-Te, with a minor residual signal persisting for U-Sb, together with preservation of the aromatic and vinylic resonances of the coumarin core and a shift in ν(C=O) from 1701 cm to ¹ to 1667–1683 cm⁻¹, is consistent with metal binding through the C7-phenolato oxygen. Antiproliferative activity and cytotoxicity were evaluated in MCF-7 and MDA-MB-231 breast cancer cells and in non-tumorigenic MCF-10A cells at 24 and 48 h, by crystal violet (CV) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. The coordination compounds displayed metal- and cell-line-dependent activity relative to free umbelliferone. U-Te (IC₅₀ = 7.4 µM) and U-Sb (9.5 µM) were the most potent in MCF-7 cells, while U-Bi (9.8 µM) was the most active in MDA-MB-231 cells, all at 24 h. IC₅₀ values in MCF-10A cells were ≥181 µM for every compound at 24 h, yielding selectivity indices >17 for the most active members of the series. Treated tumor cells showed morphological changes consistent with cytotoxicity (rounding, loss of adhesion, and monolayer disruption). These findings identify U-Sb, U-Te, and U-Bi as the most active and selective compounds of the series and support further investigation of umbelliferone-derived coordination compounds as potential antiproliferative agents. However, further investigation is needed to determine the relative contributions of intact compounds and solution-derived species to the observed biological effects.

Tumors have high requirements in terms of nutrients and oxygen. Angiogenesis is the classical mechanism for vessel formation. Tumoral vascularization has the function of nourishing the cancer cells to support tumor growth. Vasculogenic mimicry, a novel intratumoral microcirculation system, alludes to the ability of cancer cells to organize in three-dimensional (3D) channel-like architectures. It also supplies the tumors with nutrients and oxygen. Both mechanisms operate in a coordinated way; however, their functions in breast cancer stem-like cells and their regulation by microRNAs remain elusive. In the present study, we investigated the functional role of microRNA-204 (miR-204) on angiogenesis and vasculogenic mimicry in breast cancer stem-like cells. Using flow cytometry assays, we found that 86.1% of MDA-MB-231 and 92% of Hs-578t breast cancer cells showed the CD44+/CD24− immunophenotype representative of cancer stem-like cells (CSCs). The MDA-MB-231 subpopulation of CSCs exhibited the ability to form mammospheres, as expected. Interestingly, we found that the restoration of miR-204 expression in CSCs significantly inhibited the number and size of the mammospheres. Moreover, we found that MDA-MB-231 and Hs-578t CSCs efficiently undergo angiogenesis and hypoxia-induced vasculogenic mimicry in vitro. The transfection of precursor miR-204 in both CSCs was able to impair the angiogenesis in the HUVEC cell model, which was observed as a diminution in the number of polygons and sprouting cells. Remarkably, miR-204 mimics also resulted in the inhibition of vasculogenic mimicry formation in MDA-MB-231 and Hs-578t CSCs, with a significant reduction in the number of channel-like structures and branch points. Mechanistically, the effects of miR-204 were associated with a diminution of pro-angiogenic VEGFA and β-catenin protein levels. In conclusion, our findings indicated that miR-204 abrogates the angiogenesis and vasculogenic mimicry development in breast cancer stem-like cells, suggesting that it could be a potential tool for breast cancer intervention based on microRNA replacement therapies.

Excess body weight and obesity have become significant risk factors for cancer development. During obesity, adipose tissue alters its biological function, deregulating the secretion of bioactive factors such as hormones, cytokines, and adipokines that promote an inflammatory microenvironment conducive to carcinogenesis and tumor progression. Adipokines regulate tumor processes such as apoptosis, proliferation, migration, angiogenesis, and invasion. Additionally, it has been found that they can modulate autophagy, a process implicated in tumor suppression in healthy tissue and cancer progression in established tumors. Since the tumor-promoting role of autophagy has been well described, the process has been suggested as a therapeutic target in cancer. However, the effects of targeting autophagy might depend on the tumor type and microenvironmental conditions, where circulating adipokines could influence the role of autophagy in cancer. Here, we review recent evidence related to the role of adipokines in cancer cell autophagy in an effort to understand the tumor response in the context of obesity under the assumption of an autophagy-targeting treatment.

Leptin is one of the main adipokines secreted in breast tissue, and has been associated with epithelial-mesenchymal transition (EMT) and tumor progression in breast cancer. Leptin promotes EMT, cell migration and invasion in epithelial breast cells, leading to tumor progression. However, the molecular mechanism that underlies these events is not fully understood; however, the activation of different signaling pathways appears to be essential. In this sense, the effect of leptin on the activation of kinases like Src and FAK, which regulate signaling pathways that activate the EMT program, has not been completely described. Therefore, we investigated the involvement of these kinases using an in vitro model for leptin-induced EMT process in the non-tumorigenic MCF10A cell line. To this end, MCF10A cells were stimulated with leptin, and Src and FAK activation was assessed. Specific events occurring during EMT were also evaluated in the presence or absence of the kinases’s chemical inhibitors PP2 and PF-573228. For instance, we tested the expression and subcellular localization of the EMT-related transcription factors Twist and □-catenin, by western blot and immunofluorescence. We also evaluated the secretion and activation of matrix metalloproteases (MMP-2 and MMP-9) by gelatin zymography. Invasiveness properties of leptin-stimulated cells were determined by invadopodia formation assays, and by the transwell chamber method. Our results showed that leptin promotes EMT through Src and FAK activation, which leads to the secretion and activation of MMP-2 and MMP-9, invadopodia formation and cell invasion in MCF10A cells. In conclusion, our data suggest that leptin promotes an increase in the expression levels of Twist and □-catenin, the secretion of MMP-2, MMP-9, the invadopodia formation and invasion in MCF10A cells in a Src and FAK-dependent manner.