Sampath, P. | Search bioRxiv

bioRxiv2026

Inhibition of miR-1307 Reverses Resistance to Cisplatin in Drug-Resistant Oral Squamous Cell Carcinoma

BackgroundChemo-resistance remains a major clinical challenge in Oral Squamous Cell Carcinoma (OSCC), attributed to the intrinsically resistant cells. Although tumour-derived extracellular vesicles (EVs) have been implicated in cell-cell communication, their role in propagating chemo-resistance remains poorly defined. This study aims to identify salivary EV-associated miRNAs capable of predicting chemoresistance and to delineate the role of miR-1307-5p in modulating CSC-driven therapeutic refractoriness. MethodsSalivary EV-derived expression profile of miR-1307-5p was assessed by qPCR in chemo resistant OSCC patients and further validated in TCGA small RNA sequencing datasets. Expression was validated by qPCR and correlated with clinicopathological outcomes. Functional assays including cell-cycle analysis, apoptosis, migration/invasion, 3D spheroids, angiogenesis, and CAM assays were performed in miR-1307-5p inhibited CD44 CSC subpopulation compared to its vehicular control. Transcriptomic profiling cross-referencing with TCGA was conducted to identify potential novel targets of miR-1307-5p. Chemo-sensitisation was assessed by treating the knockdown chemo resistant cells with low dose cisplatin and validating it using in-vitro functional assays and orthotopic xenograft model. ResultsmiR-1307-5p was significantly elevated in salivary EVs of chemo resistant OSCC patients and correlated with poor overall survival (p = 0.03). The miRNA was markedly enriched in endogenously resistant CD44 CSCs. Silencing of miR-1307-5p induced G2/M arrest, triggered apoptosis, impaired invasion, and reduced angiogenesis both in-vitro and in ex-vivo assays. Transcriptomic profiling, TCGA validation, and integrative pathway analysis identified key oncogenic hubs which converge on PI3K-AKT, MAPK/ERK, and YAP signalling pathways governing EMT. Inhibition of miR-1307-5p restored cisplatin sensitivity in resistant CSCs, with low-dose cisplatin producing substantial tumour suppression in-vitro and in-vivo. Reduced CD44 expression in xenograft models confirmed CSC reprogramming. EVs from anti-miR-treated cells confer chemo sensitisation upon uptake by resistant CSCs. Xenograft models substantiated that EVs can initiate tumour formation and that EV-mediated delivery of anti-miR-1307-5p drives significant tumour regression. ConclusionThis study identifies salivary EV-derived miR-1307-5p as a clinically relevant biomarker of chemoresistance in OSCC and reveals its mechanistic role in sustaining CSC-driven therapeutic failure. Targeting miR-1307-5p offers a promising avenue for restoring cisplatin sensitivity and developing exosome-based therapeutic strategies. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=150 SRC="FIGDIR/small/709730v1_ufig1.gif" ALT="Figure 1"> View larger version (38K): org.highwire.dtl.DTLVardef@19f88e0org.highwire.dtl.DTLVardef@d36b95org.highwire.dtl.DTLVardef@3c2579org.highwire.dtl.DTLVardef@c04ef5_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2020

BRAWNIN: A sORF-encoded Peptide Essential for Vertebrate Mitochondrial Complex III Assembly

The emergence of small open reading frame (sORF)-encoded peptides (SEPs) is rapidly expanding the known proteome at the lower end of the size distribution1,2. Here, we show that the mitochondria proteome is enriched for proteins smaller than 100 a.a. (defined as SEPs). Using a mitochondrial prediction and validation pipeline for small open-reading-frame (sORF)-encoded peptides (SEPs), we report the discovery of 16 endogenous mitochondrial SEPs (mito-SEPs) associated with oxidative phosphorylation (OXPHOS). Through functional prediction, proteomics, metabolomics and metabolic flux modeling, we demonstrate that BRAWNIN (BR), a 71 amino acid peptide encoded by the C12orf73 gene, is essential for respiratory chain complex III (CIII) assembly. In human cells, BR is induced by the energy-sensing AMPK pathway, and its depletion impairs mitochondrial ATP production. In vivo, BR is enriched in muscle tissues and its maternal zygotic deletion in zebrafish causes complete CIII loss, resulting in severe growth retardation, lactic acidosis and early death. Our findings demonstrate that BR is essential for oxidative phosphorylation across vertebrate species. We propose that mito-SEPs are an untapped resource for essential regulators of oxidative metabolism.

cell biology↗

bioRxiv2019

Integrative analysis identifies key molecular signatures underlying neurodevelopmental deficits in Fragile X Syndrome

Fragile X syndrome (FXS) is an incurable neurodevelopmental disorder with no effective treatment. FXS is caused by epigenetic silencing of FMR1 and loss of FMRP expression. To investigate the consequences of FMRP deficiency in the context of human physiology, we established isogenic FMR1 knockout (FMR1KO) human embryonic stem cells (hESCs). Integrative analysis of the transcriptomic and proteomic profiles of hESC-derived FMRP-deficient neurons revealed several dysregulated pathways important for brain development including processes related to axon development, neurotransmission, and the cell cycle. We functionally validated alterations in a number of these pathways, showing abnormal neural rosette formation and increased neural progenitor cell proliferation in FMR1KO cells. We further demonstrated neurite outgrowth and branching deficits along with impaired electrophysiological network activity in FMRP-deficient neurons. Using isogenic FMR1KO hESC-derived neurons, we reveal key molecular signatures and neurodevelopmental abnormalities arising from loss of FMRP. We anticipate that the FMR1KO hESCs and the neuronal transcriptome and proteome datasets will provide a platform to delineate the pathophysiology of FXS in human neural cells.

neuroscience↗