介紹：改善日益增長早期患者庫的結果需要開發輔助非手術治療策略，這些策略傳統上集中在晚期非小細胞肺癌。二甲雙胍是一種廣泛使用的II型糖尿病藥物，具有長期的安全性和最小的副作用，也被認為具有抗癌活性。我們之前已經證明二甲雙胍在I期非小細胞肺癌中的抗癌作用取決於患者體重指數(BMI)。為了深入了解這些環境依賴效應的分子機製，我們試圖在小鼠肺癌模型中模擬高BMI狀態和二甲雙胍的效應。

Introduction:Improving outcomes for the growing early-stage patient pool requires developing adjuvant non-surgical therapeutic strategies, which have been traditionally focused on late-stage NSCLC. Metformin, a widely used type II diabetes drug with a long history of safety and minimal side effects, is also known to show anti-cancer activity. We have previously demonstrated that the anti-cancer effects metformin in stage I NSCLC is dependent on patient Body mass index (BMI). To gain insight into the molecular mechanism responsible for these context-dependent effects, we sought to model the effects of high-BMI status and metformin in a mouse model of lung cancer.

方法：通過給C57BL/6小鼠喂食高脂飲食16周，建立飲食誘導肥胖(DIO)，年齡/性別匹配的對照組小鼠以正常飲食喂養。來自肥胖組和非肥胖組的隊列皮下注射Lewis肺癌(LLC)細胞，隨後進行監測，直到發現已形成的腫瘤為止(~11天)。荷瘤小鼠每兩天腹腔注射二甲雙胍(50mg/kg)，連續測量腫瘤生長。流式細胞術用於測量腫瘤免疫微環境，RNA-seq用於測量比較人群中腫瘤的基因表達。

Methods:Diet-induced obesity (DIO) was established by feeding C57BL/6 mice a high-fat diet for 16 weeks. Age/sex-matched control mice were fed a normal diet. Cohorts from obese and non-obese groups were injected subcutaneously with Lewis lung carcinoma (LLC) cells and subsequently monitored until established tumors were noted (~day 11). Tumor-bearing mice were then injected intraperitoneally every two days with metformin (50 mg/kg), and tumor growth was serially measured. Flow cytometry was used to measure tumor immune microenvironment and RNA-seq was used to measure gene expression of tumors in comparison populations.

結果

圖1總結了我們的結果。未服用二甲雙胍的肥胖小鼠支持腫瘤的強勁生長。然而，二甲雙胍治療的肥胖小鼠的腫瘤生長受到抑製。相比之下，二甲雙胍對非肥胖小鼠的治療並不影響腫瘤的進展，這與肺部患者的生存數據一致。二甲雙胍對肥胖和非肥胖小鼠的免疫檢查點分子有不同的影響。特別值得注意的是二甲雙胍治療肥胖小鼠腫瘤相關調節性T細胞PD-1和CTLA-4水平的降低。與非肥胖對照組相比，二甲雙胍也降低了肥胖小鼠腫瘤浸潤淋巴細胞中表達PD-1的CD8+T細胞的頻率。對這些小鼠腫瘤中基因表達的轉錄組分析也揭示了二甲雙胍對與白細胞記憶/效應器分化調節相關的基因編碼因子以及在代謝和生物合成途徑中具有已知作用的基因的肥胖依賴性影響。

Results:Figure 1 summarizes our results. Obese mice given no metformin supported robust tumor growth. However, tumor growth was suppressed in metformin-treated obese mice. In contrast, and in agreement with lung patient survival data, metformin treatment of non-obese mice did not affect tumor progression. Immune checkpoint molecules were divergently affected by metformin in obese and non-obese mice. Particularly notable were the reductions seen in the levels of PD-1 and CTLA-4 on tumor-associated regulatory (Treg) T cells in metformin-treated obese mice. The frequencies of PD-1-expressing CD8+ T cells among tumor-infiltrating lymphocytes were also reduced by metformin in obese mice compared to non-obese controls. Transcriptome analysis of gene expression in the tumors of these mice also revealed obesity-dependent effects of metformin on genes encoding factors relevant to the regulation of leukocyte memory/effector differentiation as well as genes with known roles in metabolic and biosynthetic pathways.

結論：在高BMI患者中觀察到的二甲雙胍的促生存和抗腫瘤作用是跨物種的，因此可以在廣泛使用的小鼠模型中進行機理探討。研究結果表明，二甲雙胍對高BMI肺癌患者和肥胖小鼠的免疫調節作用可能源於獨特的代謝條件，這種代謝條件可以提供抗腫瘤免疫反應的最佳重塑。

Conclusion:Pro-survival and anti-tumor effects of metformin observed in high-BMI patients are operative across species and can therefore be explored mechanistically in widely used mouse models. Our results suggest that the immune-modifying effects of metformin seen in high-BMI lung cancer patients and obese mice alike may stem from unique metabolic conditions that afford optimal reshaping of the anti-tumor immune response.