Department of Medical Sciences, Graduate School, Soonchunhyang University, Asan-si, 31538, Republic of Korea.
Department of Biomedical Laboratory Science, College of Medical Sciences, Soonchunhyang University, Asan-si, 31538, Republic of Korea.
Breast Cancer Res. 2023 Oct 25;25(1):128. doi: 10.1186/s13058-023-01732-2.
Gremlin-1 (GREM1) and Gremlin-2 (GREM2) are bone morphogenetic protein antagonists that play important roles in organogenesis, tissue differentiation, and tissue homeostasis. Although GREM1 has been reported to be involved in promoting various cancers, little has been reported about effects of GREM2 on cancer. Recently, it has been reported that GREM2 can inhibit adipogenesis in adipose-derived stromal/stem cells. However, as an inhibitor of adipogenesis, the role of GREM2 in cancer progression is not well understood yet.
Pre-adipocyte 3T3-L1 cells overexpressing mock or Grem2 were established using a lentiviral transduction system and differentiated into adipocytes-mock and adipocytes-Grem2, respectively. To investigate the effect of adipocyte-Grem2 on breast cancer cells, we analyzed the proliferative and invasion abilities of spheroids using a 3D co-culture system of breast cancer cells and adipocytes or conditioned medium (CM) of adipocytes. An orthotopic breast cancer mouse model was used to examine the role of adipocytes-Grem2 in breast cancer progression.
Grem2 overexpression suppressed adipogenesis of 3T3-L1 cells. Proliferative and invasion abilities of spheroids formed by co-culturing MTV/TM-011 breast cancer cells and adipocytes-Grem2 were significantly reduced compared to those of spheroids formed by co-culturing MTV/TM-011 cells and adipocytes-mock. Compared to adipocytes-mock, adipocytes-Grem2 showed decreased mRNA expression of several adipokines, notably IL-6. The concentration of IL-6 in the CM of these cells was also decreased. Proliferative and invasive abilities of breast cancer cells reduced by adipocytes-Grem2 were restored by IL-6 treatment. Expression levels of vimentin, slug, and twist1 in breast cancer cells were decreased by treatment with CM of adipocytes-Grem2 but increased by IL-6 treatment. In orthotopic breast cancer mouse model, mice injected with both MTV/TM-011 cells and adipocytes-Grem2 showed smaller primary tumors and lower lung metastasis than controls. However, IL-6 administration increased both the size of primary tumor and the number of metastatic lung lesions, which were reduced by adipocytes-Grem2.
Our study suggests that GREM2 overexpression in adipocytes can inhibit adipogenesis, reduce the expression and secretion of several adipokines, including IL-6, and ultimately inhibit breast cancer progression.
Gremlin-1（GREM1）和 Gremlin-2（GREM2）是骨形态发生蛋白的拮抗剂，在器官发生、组织分化和组织稳态中发挥重要作用。尽管已有报道称 GREM1 参与促进多种癌症，但关于 GREM2 对癌症的影响知之甚少。最近，有报道称 GREM2 可以抑制脂肪细胞向脂肪细胞分化。然而，作为脂肪生成的抑制剂，GREM2 在癌症进展中的作用尚不清楚。
使用慢病毒转导系统建立了过表达 mock 或 Grem2 的前脂肪细胞 3T3-L1 细胞，并分别分化为脂肪细胞-mock 和脂肪细胞-Grem2。为了研究脂肪细胞-Grem2 对乳腺癌细胞的影响，我们使用乳腺癌细胞和脂肪细胞的 3D 共培养系统或脂肪细胞的条件培养基（CM）分析了球体的增殖和侵袭能力。使用原位乳腺癌小鼠模型研究了脂肪细胞-Grem2 在乳腺癌进展中的作用。
Grem2 过表达抑制了 3T3-L1 细胞的脂肪生成。与共培养 MTV/TM-011 乳腺癌细胞和脂肪细胞-mock 形成的球体相比，共培养 MTV/TM-011 乳腺癌细胞和脂肪细胞-Grem2 形成的球体的增殖和侵袭能力显著降低。与脂肪细胞-mock 相比，脂肪细胞-Grem2 的几种脂肪细胞因子的 mRNA 表达降低，尤其是 IL-6。这些细胞 CM 中的 IL-6 浓度也降低了。用 IL-6 处理可恢复脂肪细胞-Grem2 降低的乳腺癌细胞的增殖和侵袭能力。用脂肪细胞-Grem2 的 CM 处理后，乳腺癌细胞中波形蛋白、slug 和 twist1 的表达水平降低，但用 IL-6 处理后表达水平升高。在原位乳腺癌小鼠模型中，与对照组相比，注射 MTV/TM-011 细胞和脂肪细胞-Grem2 的小鼠原发性肿瘤较小，肺转移较少。然而，IL-6 的给药增加了原发性肿瘤的大小和转移性肺病变的数量，而这些病变被脂肪细胞-Grem2 减少了。
我们的研究表明，脂肪细胞中 GREM2 的过表达可抑制脂肪生成，降低包括 IL-6 在内的几种脂肪细胞因子的表达和分泌，最终抑制乳腺癌的进展。
