The Dual Face of Gingival Mesenchymal Stem Cell Paracrine Signalling in Oral Squamous Cell Carcinoma: A Pro-Tumour Transcriptional Programme and a Hypothesis-Generating Drug-Repurposing Screen

Background: In our companion study, the gingival mesenchymal stem cell (GMSC) secretome suppresses oxidative stress and induces apoptosis in primary oral squamous cell carcinoma (OSCC) cells, where those wet-lab results are themselves reported as preliminary; here we ask whether it also engages a proliferation × migration programme in patient tissue. The two arms differ in read-out type (apoptosis and redox there, transcript abundance here), not in opposed function. Methods: Primary OSCC cells received GMSC-conditioned medium (GMSC-CM) or indirect Transwell co-culture, assayed by RT-qPCR (VEGFA, TGFB1, MMP9, CXCL12, CCND1, PCNA, MYC, EGFR), MTT, and scratch-wound migration. Thirteen computational layers plus a GeoMx spatial verify-and-decide layer were applied to public data: TCGA-HNSC, GEO, CPTAC, single-cell inference, prognostic modelling, DepMap and LINCS L1000. Results: All eight transcripts were raised in all three arms (16 of 24 comparisons significant), indicating a pro-tumour transcriptional shift; metabolic activity was unchanged and wound closure was reduced under conditioned medium (p < 0.01). Of 1358 genes significant in all three modalities, 1219 (89.8%, 95% CI 88.0–91.3%) share direction against 25.0% expected by chance (3.59-fold; exact binomial p below machine precision). The pre-registered oral-cavity signature did not validate externally (GSE41613; C = 0.562), and no ligand–receptor pair survived permutation calibration. Conclusions: GMSC paracrine exposure induces a pro-tumour transcriptional programme in primary OSCC cells that replicates at patient level, without demonstrated functional or therapeutic consequence; gefitinib is nominated only as a hypothesis-generating candidate. The evidence rests on three primary cultures (n = 3), one GMSC donor preparation, one 24 h time point, a single reference gene, no cell-line authentication and no test of gefitinib; the study programme has concluded, and these experiments cannot be performed now.