Antitumor activity of pluripotent cell-engineered vaccines and their potential to treat lung cancer in relation to different levels of irradiation

Cancer stem cells (CSCs) are critical for tumor initiation/maintenance and recurrence or metastasis, so they may serve as a potential therapeutic target. However, CSC-established multitherapy resistance and immune tolerance render tumors resistant to current tumor-targeted strategies. To address this, renewable multiepitope-integrated spheroids based on placenta-derived mesenchymal stem cells (pMSCs) were X-ray-modified, at four different irradiation levels, including 80, 160, 240, and 320 Gy, as pluripotent biologics, to inoculate hosts bearing Lewis lung carcinoma (LL2) and compared with X-ray-modified common LL2 cells as control. We show that the vaccines at the 160/240 Gy irradiation levels could rapidly trigger tumor cells into the apoptosis loop and evidently prolong the tumor-bearing host's survival cycle, in contrast to vaccines irradiated at other levels (P<0.05), with tumor-sustaining stromal cell-derived factor-1/CXCR4 pathway being selectively blockaded. Meanwhile, almost no or minimal toxicity was detected in the vaccinated hosts. Importantly, 160/240 Gy-irradiated vaccines could provoke significantly higher killing of CSCs and non-CSCs, which may provide an access to developing a novel biotherapy against lung carcinoma.