Recently, there has been an increasing focus on cellular morphology and mechanical behavior in order to gain a better understanding of the modulation of cell malignancy. This study used uniaxial-stretching technology to select a mechanical regimen able to elevate SAOS-2 cell migration, which is crucial in osteosarcoma cell pathology. Using confocal and atomic force microscopy, we demonstrated that a 24 h 0.5% cyclic elongation applied at 1 Hz induces morphological changes in cells. Following mechanical stimulation, the cell area enlarged, developing a more elongated shape, which disrupted the initial nuclear-to-cytoplasm ratio. The peripheral cell surface also increased its roughness. Cell-based biochemical assays and real-time PCR quantification showed that these morphologically induced changes are unrelated to the osteoblastic differentiative grade. Interestingly, two essential cell-motility properties in the modulation of the metastatic process changed following the 24 h 1 Hz mechanical stimulation. These were cell adhesion and cell migration, which, in fact, were dampened and enhanced, respectively. Notably, our results showed that the stretch-induced up-regulation of cell motility occurs through a mechanism that does not depend on matrix metalloproteinase (MMP) activity, while the inhibition of ion–stretch channels could counteract it. Overall, our results suggest that further research on mechanobiology could represent an alternative approach for the identification of novel molecular targets of osteosarcoma cell malignancy.

Background: We had previously synthetized a macromolecular prodrug consisting of oxidized Alginate and dopamine (AlgOx-Da) for a potential application in Parkinson disease (PD). Methods: In the present work, we aimed at gaining an insight into the interactions occurring between AlgOx-Da and SH-SY5Y neuronal cell lines in view of further studies oriented towards PD treatment. With the scope of ascertaining changes in the external and internal structure of the cells, multiple methodologies were adopted. Firstly, fluorescently labeled AlgOx-Da conjugate was synthetized in the presence of fluorescein 5(6)-isothiocyanate (FITC), providing FITC-AlgOx-Da, which did not alter SH-SY5Y cell viability according to the sulforhodamine B test. Furthermore, the uptake of FITC-AlgOx-Da by the SH-SY5Y cells was studied using scanning near-field optical microscopy and assessments of cell morphology over time were carried out using atomic force microscopy. Results: Notably, the AFM methodology confirmed that no relevant damage occurred to the neuronal cells. Regarding the effects of DA on the intracellular reactive oxygen species (ROS) production, AlgOx-Da reduced them in comparison to free DA, while AlgOx did almost not influence ROS production. Conclusions: these findings seem promising for designing in vivo studies aiming at administering Oxidized Alginate Dopamine Conjugate for PD treatment.

Citrate-capped gold nanoparticles (AuNPs) were functionalized with three distinct antitumor gold(III) complexes, e.g., [Au(N,N)(OH)₂][PF₆], where (N,N)=2,2′-bipyridine; [Au(C,N)(AcO)₂], where (C,N)=deprotonated 6-(1,1-dimethylbenzyl)-pyridine; [Au(C,N,N)(OH)][PF₆], where (C,N,N)=deprotonated 6-(1,1-dimethylbenzyl)-2,2′-bipyridine, to assess the chance of tracking their subcellular distribution by atomic force microscopy (AFM), and surface enhanced Raman spectroscopy (SERS) techniques. An extensive physicochemical characterization of the formed conjugates was, thus, carried out by applying a variety of methods (density functional theory—DFT, UV/Vis spectrophotometry, AFM, Raman spectroscopy, and SERS). The resulting gold(III) complexes/AuNPs conjugates turned out to be pretty stable. Interestingly, they exhibited a dramatically increased resonance intensity in the Raman spectra induced by AuNPs. For testing the use of the functionalized AuNPs for biosensing, their distribution in the nuclear, cytosolic, and membrane cell fractions obtained from human lymphocytes was investigated by AFM and SERS. The conjugates were detected in the membrane and nuclear cell fractions but not in the cytosol. The AFM method confirmed that conjugates induced changes in the morphology and nanostructure of the membrane and nuclear fractions. The obtained results point out that the conjugates formed between AuNPs and gold(III) complexes may be used as a tool for tracking metallodrug distribution in the different cell fractions.

Osteosarcoma (OS), the most common primary malignant bone tumor arising in the highly mechanosensitive bone tissue, exhibits marked heterogeneity and resistance to conventional therapies. While molecular drivers have been extensively characterized, the role of mechanical stimuli in OS progression remains underexplored. In this study, we identify the transient receptor potential vanilloid 1 (TRPV1) channel as a key regulator of mechanotransduction and drug responsiveness in OS cells. Using uniaxial cyclic stretch, we show that the highly aggressive U-2 OS cell model undergoes TRPV1-dependent perpendicular reorientation, in contrast to the inert response observed in the less aggressive SAOS-2 cells. Through confocal microscopy, immunohistochemistry, and atomic force microscopy, we demonstrate that nanomolar concentrations of capsaicin—a well-characterized TRPV1 agonist—chemically replicate the mechanical phenotype, altering metastatic traits such as cell adhesion, edge architecture, migration rate, nuclear-to-cytoplasmic ratio, and chemotherapeutic sensitivity to doxorubicin and cisplatin. TRPV1 activation, whether mechanical or chemical, elicits subtype-specific effects absent in healthy hFOB osteoblasts. Notably, it differentially regulates nuclear localization of the pro-to-oncogene Src in U-2 OS versus SAOS-2 cells. Parallel changes in Src and acetylated histone H3 (acH3) levels support a role for TRPV1 as a molecular switch in the Src–acH3 mechanosignaling axis. These TRPV1-mediated effects were not observed in non-malignant cells, underscoring their tumor specificity. Our findings position TRPV1 as a mechanosensitive signaling hub that integrates mechanical and chemical cues to drive epigenetic remodeling and phenotypic plasticity in OS, offering a potential therapeutic target—particularly in aggressive, drug-resistant subtypes.

Osteosarcoma (OS), the most common primary malignant bone tumor, arises in highly mechanosensitive tissue and exhibits marked heterogeneity and resistance to conventional therapies. While molecular drivers have been extensively characterized, the role of mechanical stimuli in OS progression remains underexplored. Here, we identify the transient receptor potential vanilloid 1 (TRPV1) channel as a key regulator of mechanotransduction and drug responsiveness in OS cells. Using uniaxial cyclic stretch, we show that aggressive U-2 OS cells undergo TRPV1-dependent perpendicular reorientation, unlike the inert SAOS-2 cells. Confocal microscopy, immunohistochemistry, and atomic force microscopy reveal that nanomolar concentrations of capsaicin—a well-characterized TRPV1 agonist—chemically mimic this mechanical phenotype, altering metastatic traits including adhesion, edge architecture, migration, nuclear-to-cytoplasmic ratio, and sensitivity to doxorubicin and cisplatin. TRPV1 activation, whether mechanical or chemical, induces subtype-specific effects absent in healthy hFOB osteoblasts. Notably, it differentially regulates nuclear localization of the proto-oncogene Src in U-2 OS versus SAOS-2 cells. Corresponding changes in Src and acetylated histone H3 (acH3) levels support a role for TRPV1 in modulating the Src–acH3 mechanosignaling axis. These effects are tumor-specific, positioning TRPV1 as a mechanosensitive signaling hub that integrates mechanical and chemical cues to drive epigenetic remodeling and phenotypic plasticity in OS, with potential as a therapeutic target in aggressive, drug-resistant subtypes