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Browsing by Author "Li, Fangjia"
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Item Mechanical tibial loading remotely suppresses brain tumors by dopamine-mediated downregulation of CCN4(Springer Nature, 2021-05-24) Fan, Yao; Zha, Rongrong; Sano, Tomohiko; Zhao, Xinyu; Liu, Shengzhi; Woollam, Mark D.; Wu, Di; Sun, Xun; Li, Kexin; Egi, Motoki; Li, Fangjia; Minami, Kazumasa; Siegel, Amanda P.; Horiuchi, Takashi; Liu, Jing; Agarwal, Mangilal; Sudo, Akihiro; Nakshatri, Harikrishna; Li, Bai-Yan; Yokota, Hiroki; Biomedical Engineering, School of Engineering and TechnologyMechanical loading to the bone is known to be beneficial for bone homeostasis and for suppressing tumor-induced osteolysis in the loaded bone. However, whether loading to a weight-bearing hind limb can inhibit distant tumor growth in the brain is unknown. We examined the possibility of bone-to-brain mechanotransduction using a mouse model of a brain tumor by focusing on the response to Lrp5-mediated Wnt signaling and dopamine in tumor cells. The results revealed that loading the tibia with elevated levels of tyrosine hydroxylase, a rate-limiting enzyme in dopamine synthesis, markedly reduced the progression of the brain tumors. The simultaneous application of fluphenazine (FP), an antipsychotic dopamine modulator, enhanced tumor suppression. Dopamine and FP exerted antitumor effects through the dopamine receptors DRD1 and DRD2, respectively. Notably, dopamine downregulated Lrp5 via DRD1 in tumor cells. A cytokine array analysis revealed that the reduction in CCN4 was critical for loading-driven, dopamine-mediated tumor suppression. The silencing of Lrp5 reduced CCN4, and the administration of CCN4 elevated oncogenic genes such as MMP9, Runx2, and Snail. In summary, this study demonstrates that mechanical loading regulates dopaminergic signaling and remotely suppresses brain tumors by inhibiting the Lrp5-CCN4 axis via DRD1, indicating the possibility of developing an adjuvant bone-mediated loading therapy.Item Overexpression of Lrp5 enhanced the anti-breast cancer effects of osteocytes in bone(Springer Nature, 2021-07-06) Liu, Shengzhi; Wu, Di; Sun, Xun; Fan, Yao; Zha, Rongrong; Jalali, Aydin; Feng, Yan; Li, Kexin; Sano, Tomohiko; Vike, Nicole; Li, Fangjia; Rispoli, Joseph; Sudo, Akihiro; Liu, Jing; Robling, Alexander; Nakshatri, Harikrishna; Li, Bai-Yan; Yokota, Hiroki; Biomedical Engineering, School of Engineering and TechnologyOsteocytes are the most abundant cells in bone, which is a frequent site of breast cancer metastasis. Here, we focused on Wnt signaling and evaluated tumor-osteocyte interactions. In animal experiments, mammary tumor cells were inoculated into the mammary fat pad and tibia. The role of Lrp5-mediated Wnt signaling was examined by overexpressing and silencing Lrp5 in osteocytes and establishing a conditional knockout mouse model. The results revealed that administration of osteocytes or their conditioned medium (CM) inhibited tumor progression and osteolysis. Osteocytes overexpressing Lrp5 or β-catenin displayed strikingly elevated tumor-suppressive activity, accompanied by downregulation of tumor-promoting chemokines and upregulation of apoptosis-inducing and tumor-suppressing proteins such as p53. The antitumor effect was also observed with osteocyte-derived CM that was pretreated with a Wnt-activating compound. Notably, silencing Lrp5 in tumors inhibited tumor progression, while silencing Lrp5 in osteocytes in conditional knockout mice promoted tumor progression. Osteocytes exhibited elevated Lrp5 expression in response to tumor cells, implying that osteocytes protect bone through canonical Wnt signaling. Thus, our results suggest that the Lrp5/β-catenin axis activates tumor-promoting signaling in tumor cells but tumor-suppressive signaling in osteocytes. We envision that osteocytes with Wnt activation potentially offer a novel cell-based therapy for breast cancer and osteolytic bone metastasis.Item Skeletal loading regulates breast cancer-associated osteolysis in a loading intensity-dependent fashion(Springer Nature, 2020-02-14) Fan, Yao; Jalali, Aydin; Chen, Andy; Zhao, Xinyu; Liu, Shengzhi; Teli, Meghana; Guo, Yunxia; Li, Fangjia; Li, Junrui; Siegel, Amanda; Yang, Lianxiang; Liu, Jing; Na, Sungsoo; Agarwal, Mangilal; Robling, Alexander G.; Nakshatri, Harikrishna; Li, Bai-Yan; Yokota, Hiroki; Biomedical Engineering, School of Engineering and TechnologyOsteocytes are mechanosensitive bone cells, but little is known about their effects on tumor cells in response to mechanical stimulation. We treated breast cancer cells with osteocyte-derived conditioned medium (CM) and fluid flow-treated conditioned medium (FFCM) with 0.25 Pa and 1 Pa shear stress. Notably, CM and FFCM at 0.25 Pa induced the mesenchymal-to-epithelial transition (MET), but FFCM at 1 Pa induced the epithelial-to-mesenchymal transition (EMT). This suggested that the effects of fluid flow on conditioned media depend on flow intensity. Fluorescence resonance energy transfer (FRET)-based evaluation of Src activity and vinculin molecular force showed that osteopontin was involved in EMT and MET switching. A mouse model of tumor-induced osteolysis was tested using dynamic tibia loadings of 1, 2, and 5 N. The low 1 N loading suppressed tumor-induced osteolysis, but this beneficial effect was lost and reversed with loads at 2 and 5 N, respectively. Changing the loading intensities in vivo also led to changes in serum TGFβ levels and the composition of tumor-associated volatile organic compounds in the urine. Collectively, this study demonstrated the critical role of intensity-dependent mechanotransduction and osteopontin in tumor-osteocyte communication, indicating that a biophysical factor can tangibly alter the behaviors of tumor cells in the bone microenvironment.Item Vinculin Force Sensor Detects Tumor-Osteocyte Interactions(Springer Nature, 2019-04-04) Li, Fangjia; Chen, Andy; Reeser, Andrew; Wang, Yue; Fan, Yao; Liu, Shengzhi; Zhao, Xinyu; Prakash, Rahul; Kota, Divya; Li, Bai-Yan; Yokota, Hiroki; Liu, Jing; Physics, School of ScienceThis study utilized a Förster resonance energy transfer (FRET)-based molecular tension sensor and live cell imaging to evaluate the effect of osteocytes, a mechanosensitive bone cell, on the migratory behavior of tumor cells. Two cell lines derived from MDA-MB-231 breast cancer cells were transfected with the vinculin tension sensor to quantitatively evaluate the force in focal adhesions of the tumor cell. Tumor cells treated with MLO-A5 osteocyte-conditioned media (CM) decreased the tensile forces in their focal adhesions and decreased their migratory potential. Tumor cells treated with media derived from MLO-A5 cells exposed to fluid flow-driven shear stress (FFCM) increased the tensile forces and increased migratory potential. Focal adhesion tension in tumor cells was also affected by distance from MLO-A5 cells when the two cells were co-cultured, where tumor cells close to MLO-A5 cells exhibited lower tension and decreased cell motility. Overall, this study demonstrates that focal adhesion tension is involved in altered migratory potential of tumor cells, and tumor-osteocyte interactions decrease the tension and motility of tumor cells.