Huang J, Woods P, Normolle D, Goff J P, Benos P V, Stehle C J, Steinman R A
Department of Medicine, University of Pittsburgh School of Medicine and University of Pittsburgh Cancer Institute, Suite 2.26f Hillman Cancer Center, 5117 Centre Avenue, Pittsburgh, PA, 15213, USA.
School of Medicine, Tsinghua University, Beijing, China.
Breast Cancer Res Treat. 2017 Jan;161(2):229-243. doi: 10.1007/s10549-016-4052-0. Epub 2016 Nov 16.
Breast cancers have a poorer prognosis if estrogen receptor expression was lost during recurrence. It is unclear whether this conversion is cell autonomous or whether it can be promoted by the microenvironment during cancer dormancy. We explored the ability of marrow-derived stromal cell lines to arrest co-cultured breast cancer cells and suppress estrogen receptor alpha (ER) expression during arrest, facilitating the emergence of estrogen-independent breast cancer clones.
Cancer cell growth, ER protein, microRNA, and mRNA levels were measured in breast cancer cell lines exposed to conditioned medium from marrow stromal lines in the presence and absence of estrogen and of signaling pathway modulators.
We demonstrate that paracrine signaling from the stromal cell line HS5 downregulated ER in T47D and MCF7 breast cancer cells. This occurred at the mRNA level and also through decreased ER protein stability. Additionally, conditioned medium (CM) from HS5 arrested the breast cancer cells in G0/G1 in part through interleukin-1 (IL1) and inhibited cancer cell growth despite the activation of proliferative pathways (Erk and AKT) by the CM. Similar findings were observed for CM from the hFOB 1.19 osteoblastic cell line but not from two other fibroblastic marrow lines, HS27A and KM101. HS5-CM inhibition of MCF7 proliferation could not be restored by exogenous ER, but was restored by the IL1-antagonist IL1RA. In the presence of IL1RA, HS5-CM activation of AKT and Erk enabled the outgrowth of breast cancer cells with suppressed ER that were fulvestrant-resistant and estrogen-independent.
We conclude that marrow-derived stromal cells can destabilize estrogen receptor protein to convert the ER status of growth-arrested ER+ breast cancer cell lines. The balance between stromal pro- and anti-proliferative signals controlled the switch from a dormant phenotype to estrogen-independent cancer cell growth.
如果雌激素受体表达在复发过程中丧失，乳腺癌的预后会更差。目前尚不清楚这种转变是细胞自主性的，还是在癌症休眠期间可由微环境促进。我们探讨了骨髓来源的基质细胞系阻止共培养的乳腺癌细胞生长以及在阻止生长期间抑制雌激素受体α（ER）表达的能力，这有助于雌激素非依赖性乳腺癌克隆的出现。
在有或无雌激素及信号通路调节剂存在的情况下，测量暴露于骨髓基质细胞系条件培养基中的乳腺癌细胞系的癌细胞生长、ER蛋白、微小RNA和mRNA水平。
我们证明，基质细胞系HS5的旁分泌信号下调了T47D和MCF7乳腺癌细胞中的ER。这发生在mRNA水平，并且也是通过降低ER蛋白稳定性实现的。此外，HS5的条件培养基（CM）部分通过白细胞介素-1（IL1）使乳腺癌细胞停滞在G0/G1期，并抑制癌细胞生长，尽管CM激活了增殖途径（Erk和AKT）。对于hFOB 1.19成骨细胞系的CM也观察到了类似的结果，但另外两个成纤维骨髓系HS27A和KM101的CM则未观察到。HS5-CM对MCF7增殖的抑制不能通过外源性ER恢复，但可通过IL1拮抗剂IL1RA恢复。在存在IL1RA的情况下，HS5-CM对AKT和Erk的激活使得ER表达受抑制的乳腺癌细胞生长，这些细胞对氟维司群耐药且不依赖雌激素。
我们得出结论，骨髓来源的基质细胞可使雌激素受体蛋白不稳定，从而改变生长停滞的ER+乳腺癌细胞系的ER状态。基质促增殖信号和抗增殖信号之间的平衡控制了从休眠表型向雌激素非依赖性癌细胞生长的转变。
