Oncopathology Research Center, Iran University of Medical Sciences, Tehran, Iran.
Division of Histology, Department of Basic Science, Faculty of Veterinary Medicine, Science and Research Branch, Islamic Azad University, Tehran, Iran.
J Cancer Res Clin Oncol. 2023 Jul;149(7):4101-4116. doi: 10.1007/s00432-022-04303-8. Epub 2022 Aug 30.
Cancer stem cells (CSCs), a rare sub-fraction of tumor cells, with the capability of self-renewal and strong oncogenicity are tightly responsible for chemo and radio resistance and tumor metastasis in colorectal cancer. Hence, CSCs targeting would improve the efficacy of therapeutic strategies and clinical outcomes.
Here, using three-dimensional CSC spheroids and syngeneic mice model, we evaluated the cancer preventive impact of CSCs-based vaccination. CSCs enrichment was performed via colonosphere formation from CT-26 cell line and CT-26-derived tumor biopsy and characterized by confirming high expression of key stemness genes (OCT4, SOX2, and NANOG) and CSC-related surface biomarkers (CD166, DCLK1, and CD133) via real-time PCR and flow cytometry, respectively. Then, the stemness phenotype and self-renewal in CSC-enriched spheroids were further confirmed by showing serial sphere formation capacity, clonogenicity potential, and enhanced in vivo tumorigenic capacity compared to their parental counterparts. CSCs lysates were used as vaccines in prophylactic settings compared to the parental cell lysate and PBS groups.
Immunization of syngeneic mice with CSCs lysates was effective in the prevention of tumor establishment and significantly decreased tumor growth rate accompanied by an improvement in survival rate in tumor-bearing mice compared to groups subjected to parental cells lysate and PBS. These results, for the first time, showed that mice immunized with cell lysate from tumor biopsy-derived spheroids are resistant to tumor induction. Immunofluorescence staining indicated that only the serum antibodies from CSC-vaccinated mice reacted with colonospheres.
These findings represent CSCs lysate-based vaccination as a potential approach to hampering immunotherapy failure of colorectal cancer which along with other traditional therapies may effectively apply to prevent the establishment of aggressive tumors harboring stemness features.
癌症干细胞（CSC）是肿瘤细胞的一个稀有亚群，具有自我更新和强烈致癌性，是导致结直肠癌化疗和放疗耐药及肿瘤转移的主要原因。因此，针对 CSC 的治疗方法将提高治疗策略的疗效和临床转归。
本研究采用三维 CSC 球体和同基因小鼠模型，评估了基于 CSC 的疫苗接种对癌症的预防作用。通过 CT-26 细胞系和 CT-26 衍生肿瘤活检的球体形成，从 CT-26 细胞系中富集 CSC，并通过实时 PCR 和流式细胞术分别确认关键干性基因（OCT4、SOX2 和 NANOG）和 CSC 相关表面标志物（CD166、DCLK1 和 CD133）的高表达，对 CSC 进行鉴定。然后，通过显示连续球体形成能力、克隆形成潜力和增强的体内致瘤能力，进一步确认 CSC 富集球体中的干性表型和自我更新能力。与亲本细胞裂解物和 PBS 组相比，CSC 裂解物被用作预防性疫苗。
与亲本细胞裂解物和 PBS 组相比，用 CSC 裂解物免疫同基因小鼠可有效预防肿瘤的建立，并显著降低肿瘤生长速度，提高荷瘤小鼠的存活率。这些结果首次表明，用肿瘤活检衍生球体的细胞裂解物免疫的小鼠对肿瘤诱导具有抗性。免疫荧光染色表明，只有来自 CSC 疫苗接种小鼠的血清抗体与结肠球体反应。
这些发现代表 CSC 裂解物疫苗接种作为一种潜在的方法，可以阻止结直肠癌免疫治疗的失败，与其他传统疗法相结合，可能有效地应用于预防具有干性特征的侵袭性肿瘤的建立。
