Biology subjects

Palma, M. B.

Publications and source records attributed to Palma, M. B..

5 recordsLinked to original sources

bioRxiv2026

Modulating SPARC Expression in Mesenchymal Stem Cells Improves Secretome-Mediated Skin Regeneration and Wound Repair

Mesenchymal stem cells (MSCs) have garnered significant attention over the past three decades due to their robust regenerative potential, primarily mediated by their paracrine activity by releasing soluble bioactive factors and extracellular vesicles (EVs). The MSC secretome plays a pivotal role in wound healing by influencing cellular migration, inflammation, angiogenesis, extracellular matrix (ECM) remodeling, and re-epithelialization. SPARC (Secreted Protein Acidic and Rich in Cysteine), a multifunctional ECM glycoprotein involved in tissue repair and remodeling, regulates key processes such as cell migration, proliferation, angiogenesis, and survival. Despite its known role in ECM dynamics, the impact of SPARC expression on the regenerative properties of MSCs remains underexplored. In this study, we hypothesized that SPARC overexpression in MSCs enhances their secretomes regenerative capacity. Using lentiviral systems, we generated SPARC-overexpressing (+SPARC) and SPARC-knockdown (KD-SPARC) MSCs to investigate SPARCs role in wound healing. Conditioned media (CM) derived from these MSCs were analyzed in vitro for their effects on human skin keratinocytes and fibroblasts. Our results revealed that SPARC expression significantly influences cell-specific migration and cell cycle. Furthermore, in an in vivo wound healing model, CM from +SPARC MSCs accelerated regeneration, while SPARC absence in MSCs CM delayed the healing process. These findings underscore the critical role of SPARC in modulating MSC secretome composition and enhancing its regenerative efficacy. This study highlights SPARC as a promising therapeutic target for the development of advanced regenerative therapies aimed at improving cutaneous wound healing outcomes.

cell biology↗

bioRxiv2025

CANNABIDIOL MODULATES CLASSICAL AND NON-CLASSICAL HLA EXPRESSION IN HUMAN CHORIOCARCINOMA CELL LINE

Cannabidiol (CBD) modulates diverse signaling pathways with potential relevance to tumor immune escape, however its impact on the regulation of classical and non-classical HLA class I molecules remains incompletely understood. Here, we examined the mechanisms by which CBD regulates HLA expression in JEG-3 choriocarcinoma cells, focusing on cannabinoid-related receptors and intracellular Ca{superscript 2} signaling. CBD increased the expression of classical HLA class I genes--most notably HLA-C--while reducing HLA-G levels, a non-classical HLA class I molecule that acts as a local immunosuppressor. Receptor profiling revealed constitutive expression of CB1 and CB2, whereas GPR55 and PPAR{gamma} expression became detectable only after CBD exposure. Functional inhibition assays showed that HLA-G downregulation was selectively attenuated by CB1 blockade, with no meaningful contribution from CB2 or GPR55. In contrast, CBD-induced HLA-C upregulation required GPR55 and CB2 activity, while being unaffected by CB1 inhibition, indicating distinct receptor pathways for classical and non-classical HLA regulation. Calcium chelation using BAPTA further demonstrated that HLA-G modulation is highly sensitive to intracellular Ca{superscript 2} reduction, whereas classical HLA expression required higher BAPTA concentrations to be affected. Altogether, these findings identify CBD as a dual immunomodulatory agent capable of enhancing tumor immune visibility while limiting immunotolerant HLA-G expression through receptor-specific and Ca{superscript 2}-dependent mechanisms.

cancer biology↗

bioRxiv2025

Cannabidiol (CBD) as a novel inhibitor of HLA-G expression in human choriocarcinoma cell line (JEG-3)

Cannabinoids have emerged as promising agents in cancer research due to their antitumor properties. While their effects on tumor growth and survival have been widely investigated, their impact on immune checkpoint regulation remains largely unexplored. In this study, we examined the effects of cannabidiol (CBD) and a high-CBD extract (CBD-HCE) on the expression of HLA-G in human choriocarcinoma JEG-3 cells. HLA-G is a non-classical HLA class I molecule associated with immune escape in tumors. Both CBD and CBD-HCE were found to reduce cell proliferation and migration, increase apoptosis, and significantly downregulate HLA-G expression at both the mRNA and protein levels. This inhibitory effect was observed to be both dose- and time-dependent, and it was completely reversible after the treatment was removed, indicating a dynamic and CBD-dependent modulation. These results provide the first experimental evidence of HLA-G downregulation by CBD and CBD-HCE, highlighting a novel immunomodulatory mechanism with potential therapeutic implications. By simultaneously targeting tumor cell viability and immune evasion, CBD-based compounds may enhance antitumor immune responses and improve the efficacy of immunotherapies. Further research involving additional tumor cell lines, in vivo models, and immune-relevant systems are necessary to validate and expand upon these findings.

cancer biology↗

bioRxiv2023

The transcription factor OCT6 promotes the dissolution of the naive pluripotent state by repressing Nanog and activating a formative state gene regulatory network.

Animal development relies on complex gene regulatory networks (GRNs) that govern the nearly irreversible changes that occur during cell differentiation. In this work we aimed to determine key transcription factors (TFs) associated with the dissolution of the naive pluripotent state and the acquisition of a formative identity. We identified OCT6 as one of the earliest TFs induced during the onset of mouse embryonic stem cell (mESCs) differentiation. To investigate its role, we generated an Oct6 knockout mESC line, which failed to acquire the characteristic cell morphology associated with the formative state. Transcriptome analysis of differentiating cells revealed nearly 300 differentially expressed genes compared to wild-type cells, including pluripotency TFs Nanog, Klf2, Nr5a2, Prdm14, and Esrrb, that failed to correctly downregulate. Notably, premature expression of OCT6 in naive cells triggered a rapid morphological transformation mirroring differentiation, accompanied by self-induction of Oct6 and expression of TFs such as Sox3, Zic2/3, Foxp1, as well as the formative genes Dnmt3A and FGF5. Strikingly, the majority of OCT6 expressing cells did not express NANOG. Gene expression and single molecule RNA-FISH analysis confirmed that this regulation was at the transcriptional level. Collectively, our results establish OCT6 as a key TF in the dissolution of the naive pluripotent state and support a model where Oct6 and Nanog form a double negative feedback loop which could act as a toggle switch important for the transition to the formative state. HighlightsO_LIOct6 is rapidly induced as mESCs exit ground state pluripotency. C_LIO_LILoss of OCT6 negatively affects the transition to formative pluripotency. C_LIO_LIPremature expression of OCT6 in mESCs is sufficient to induce a formative-like phenotype. C_LIO_LIOCT6 and NANOG repress each other forming a double negative feedback loop. C_LI

developmental biology↗

bioRxiv2021

HLA-G gene editing: a novel therapeutic alternative in cancer immunotherapy

Cancer immunotherapies based mainly on the blockade of immune-checkpoint (IC) molecules by anti-IC antibodies offer new alternatives for treatment in oncological diseases. However, a considerable proportion of patients remain unresponsive to them. Hence, the development of novel clinical immunotherapeutic approaches and/or targets are crucial. In this context, targeting the immune-checkpoint HLA-G/ILT2/ILT4 has caused great interest since it is abnormally expressed in several malignancies generating a tolerogenic microenvironment. Here, we used CRISPR/Cas9 gene editing to block the HLA-G expression in two tumor cell lines expressing HLA-G, including a renal cell carcinoma (RCC7) and a choriocarcinoma (JEG-3). Different sgRNA/Cas9 plasmids targeting HLA-G exon 1 and 2 were transfected in both cell lines. Downregulation of HLA-G was reached to different degrees, including complete silencing. Most importantly, HLA-G - cells triggered a higher in vitro response of immune cells with respect to HLA-G + wild type cells. Altogether, we demonstrated for the first time the HLA-G downregulation through gene editing. We propose this approach as a first step to develop novel clinical immunotherapeutic approaches in cancer.

cancer biology↗