Institute for Molecular Imaging and Theranostics, Chonnam National University Medical School, Gwangju, 61469, Republic of Korea.
Department of Molecular Medicine (BrainKorea21 Plus), Chonnam National University Graduate School, Gwangju, 61469, Republic of Korea.
Mol Imaging Biol. 2024 Feb;26(1):148-161. doi: 10.1007/s11307-023-01879-6. Epub 2023 Nov 28.
Attenuated Salmonella typhimurium is a potential biotherapeutic antitumor agent because it can colonize tumors and inhibit their growth. The present study aimed to develop a doxycycline (Doxy)-inducible gene switch system in attenuated S. typhimurium and assess its therapeutic efficacy in various tumor-bearing mice models.
A Doxy-inducible gene switch system comprising two plasmids was engineered to trigger the expression of cargo genes (Rluc8 and clyA). Attenuated S. typhimurium carrying Rluc8 were injected intravenously into BALB/c mice bearing CT26 tumors, and bioluminescence images were captured at specified intervals post-administration of doxycycline. The tumor-suppressive effects of bacteria carrying clyA were evaluated in BALB/c mice bearing CT26 tumors and in C57BL/6 mice bearing MC38 tumors.
Expression of the fimE gene, induced only in the presence of Doxy, triggered a unidirectional switch of the P promoter to induce expression of the cargo genes. The switch event was maintained over a long period of bacterial culture. After intravenous injection of transformed Salmonella into mice bearing CT26 tumors, the bacteria transformed with the Doxy-inducible gene switch system for Rluc8 targeted only tumor tissues and expressed the payloads 2 days after Doxy treatment. Notably, bacteria carrying the Doxy-inducible gene switch system for clyA effectively suppressed tumor growth and prolonged survival, even after just one Doxy induction.
These results suggest that attenuated S. typhimurium carrying this novel gene switch system elicited significant therapeutic effects through a single induction triggering and were a potential biotherapeutic agent for tumor therapy.
减毒鼠伤寒沙门氏菌是一种有潜力的生物治疗抗肿瘤药物，因为它可以定植肿瘤并抑制其生长。本研究旨在开发减毒鼠伤寒沙门氏菌中的强力霉素（Doxy）诱导基因开关系统，并评估其在各种荷瘤小鼠模型中的治疗效果。
设计了一个由两个质粒组成的强力霉素诱导基因开关系统，以触发货物基因（Rluc8 和 clyA）的表达。携带 Rluc8 的减毒鼠伤寒沙门氏菌被静脉注射到携带 CT26 肿瘤的 BALB/c 小鼠中，并在给予强力霉素后指定的时间间隔拍摄生物发光图像。在携带 CT26 肿瘤的 BALB/c 小鼠和携带 MC38 肿瘤的 C57BL/6 小鼠中评估携带 clyA 的细菌的肿瘤抑制作用。
只有在存在强力霉素的情况下，诱导 fimE 基因的表达会触发 P 启动子的单向开关，从而诱导货物基因的表达。该开关事件在细菌培养的很长一段时间内得以维持。在将转化后的沙门氏菌静脉注射到携带 CT26 肿瘤的小鼠中后，经强力霉素诱导的基因开关系统转化的细菌仅靶向肿瘤组织，并在强力霉素治疗后 2 天表达有效载荷。值得注意的是，携带强力霉素诱导基因开关系统的 clyA 的细菌有效地抑制了肿瘤生长并延长了生存时间，甚至在单次强力霉素诱导后也是如此。
这些结果表明，携带这种新型基因开关系统的减毒鼠伤寒沙门氏菌通过单次诱导触发产生了显著的治疗效果，是一种有潜力的肿瘤治疗生物治疗剂。
