Castration-resistant prostate cancer (CRPC) remains difficult to treat with conventional chemotherapy. We evaluated a stem cell-based enzyme-prodrug strategy using hTERT-immortalized adipose-derived stem cells engineered to express rabbit carboxylesterase 2 (hTERT-ADSC.CE2) in combination with irinotecan (CPT-11). hTERT-ADSC.CE2 cells were generated via lentiviral transduction and confirmed to overexpress CE2. Their tumor-homing capacity toward PC3 prostate cancer cells was assessed, along with prodrug activation, apoptosis induction, and in vivo tumor suppression in a CRPC mouse model. hTERT-ADSC.CE2 cells demonstrated enhanced migration toward PC3 cells and higher expression of tumor-homing factors than the controls. Under CPT-11, they exhibited a strong “suicide” effect and induced selective killing of PC3 cells, with upregulation of BAX and cleaved caspase-3 and downregulation of BCL-2. By day 14, the combination arm showed significantly lower tumor burden than both the control and irinotecan-alone arms (p < 0.05). The pattern is consistent with intratumoral activation and localized SN-38 exposure. hTERT-ADSC.CE2 combined with irinotecan provides potent, tumor-targeted cytotoxicity and markedly suppresses CRPC progression. This cell-mediated prodrug activation system may represent a promising therapeutic approach for advanced prostate cancer.

Chronic kidney disease (CKD) involves uremic toxin-driven tubular injury and systemic vascular dysfunction, in which mitochondrial impairment and apoptotic cell loss contribute to progressive tissue deterioration. Accordingly, a targeted EV platform is required to enable efficient miRNA delivery to the toxin-stressed tubular–endothelial compartment. Based on our previous study showing that melatonin restores miR-4516 levels under CKD-related stress, we directly loaded miR-4516 into engineered extracellular vesicles (EVs) to evaluate its effects on mitochondrial function and cell survival. Here, we engineered EVs with a G3-C12/RGD surface modification and established a miR-4516 loading strategy to enhance delivery to kidney proximal tubule cells and vascular endothelial cells. miR-4516 loading increased EV-associated miR-4516 levels without major changes in particle size distribution, and EV identity was supported by CD9 and CD81 expression. Confocal microscopy and flow cytometry demonstrated increased cellular uptake of miR-4516-loaded G3-C12/RGD-EVs compared with control EVs in TH1 proximal tubule cells and HUVECs. Under indoxyl sulfate stress, engineered EV treatment restored intracellular miR-4516 and improved mitochondrial function, as indicated by recovery of respiratory Complex I and Complex IV activities and improved Seahorse bioenergetic parameters (OCR/ECAR, basal and maximal respiration, ATP-linked respiration, and spare respiratory capacity). Annexin V staining further indicated reduced toxin-induced apoptosis. In an adenine diet-induced CKD mouse model, intravenous administration of miR-4516-loaded G3-C12/RGD-EVs improved urinary albumin-to-creatinine ratio (UACR), blood urea nitrogen (BUN), and serum creatinine. These findings indicate that miR-4516-loaded, targeting-engineered EVs may mitigate uremic toxin-associated mitochondrial dysfunction and renal impairment in CKD.

Colorectal cancer (CRC) remains a major cause of cancer-related deaths in advanced disease, and activating KRAS/NRAS mutations limit the use of anti-EGFR antibodies to RAS–wild-type tumors. The cellular prion protein (PrP^C) has been linked to aggressive and chemoresistant CRC, but its extracellular partners and functional relevance in KRAS-mutant disease are not fully defined. Here, we examined extracellular PrP^C complexes and PrP^C-associated signaling in CRC cell lines and xenografts using a neutralizing PrP^C monoclonal antibody. Across a CRC panel that included SNU-C5/WT and its 5-fluorouracil- and oxaliplatin-resistant derivatives, HT-29 (KRAS–wild-type), and HCT-8 and LoVo (KRAS-mutant), co-immunoprecipitation showed that PrP^C forms complexes with the 37/67 kDa laminin receptor (RPSA), with PrP^C–RPSA association particularly increased in KRAS-mutant HCT-8 and LoVo cells. PrP^C protein levels were higher in KRAS-mutant HCT-8, SW620, and SNU-407 cells than in HT-29, and PrP^C neutralization reduced viability in all four lines. Accordingly, we assessed upstream RAS activity and found that active RAS (RAS-GTP) was higher in KRAS-mutant cells than in HT-29, and PrP^C treatment was associated with reduced RAS-GTP levels. In the same KRAS-mutant setting, basal AKT phosphorylation exceeded that in HT-29, and PrP^C treatment lowered AKT phosphorylation without changing total AKT. Moreover, PrP^C treatment was associated with reduced ERK1/2 phosphorylation in KRAS-mutant cells, suggesting attenuation of downstream RAS pathway output. These signaling changes coincided with a decrease in the S-phase fraction and an increase in G1. In an HCT-8 (KRAS G13D) xenograft model, PrP^C monotherapy inhibited tumor growth in a dose-dependent manner, and 5-fluorouracil (5-FU) monotherapy produced an intermediate effect. The combination of PrP^C (10 mg/kg) and 5-FU (20 mg/kg) yielded the greatest tumor growth inhibition among the tested regimens. Consistent with this enhanced tumor control, immunofluorescence of xenograft tissues showed that PrP^C, particularly with 5-FU, reduced intratumoral PrP^C and PCNA and decreased CD31-positive microvessels and α-SMA–positive vessel structures. Taken together, these findings suggest that extracellular PrP^C supports RAS–AKT signaling, proliferation, and tumor-associated angiogenesis in KRAS-mutant colorectal cancer, and that PrP^C neutralization additively enhances 5-fluorouracil activity in KRAS-mutant models. The data provide a preclinical basis for evaluating PrP^C antibodies in combination with fluoropyrimidine-based regimens in patients with KRAS-mutant CRC.

Stem cells can selectively migrate toward cancer cells, and therapeutic genes can be introduced into stem cells. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces apoptosis in cancer cells without harming normal cells. In this study, we evaluated the inhibition of tumor growth in castration-resistant prostate cancer (CRPC) using human adipose-derived stem cells (ADSCs) engineered to express cytosine deaminase (CD) and soluble TRAIL (sTRAIL), combined with the prodrug 5-fluorocytosine (5-FC). An immortalized human ADSC line (hTERT-ADSC) was transduced with a lentiviral vector encoding CD and sTRAIL, generating ADSC.CD.sTRAIL cells. Expression of chemoattractant ligands and receptors was assessed by RT-PCR. The suicide gene effect was evaluated by 5-FC treatment, measuring cell viability and apoptosis markers in vitro. A subcutaneous CRPC mouse model was used for in vivo studies. ADSC.CD.sTRAIL cells showed enhanced migration toward prostate cancer cells. Treatment with 5-FC significantly reduced cell viability, and co-culture with PC3 cells plus 5-FC increased apoptosis marker expression. In vivo, mice treated with ADSC.CD.sTRAIL and 5-FC had significantly smaller tumor volumes than control groups, with no treatment-related toxicity observed. These findings suggest that ADSCs overexpressing CD and sTRAIL, combined with 5-FC, effectively inhibit CRPC tumor growth and represent a promising targeted therapeutic strategy.