Emerging nanomedicine-based therapeutics for hematogenous metastatic cascade inhibition: Interfering with the crosstalk between "seed and soil"

Despite considerable progresses in cancer treatment, tumor metastasis is still a thorny issue, which leads to majority of cancer-related deaths. In hematogenous metastasis, the concept of "seed and soil" suggests that the crosstalk between cancer cells (seeds) and premetastatic niche (soil) facilitates tumor metastasis. Considerable efforts have been dedicated to inhibit the tumor metastatic cascade, which is a highly complicated process involving various pathways and biological events. Nonetheless, satisfactory therapeutic outcomes are rarely observed, since it is a great challenge to thwart this multi-phase process. Recent advances in nanotechnology-based drug delivery systems have shown great potential in the field of anti-metastasis, especially compared with conventional treatment methods, which are limited by serious side effects and poor efficacy. In this review, we summarized various factors involved in each phase of the metastatic cascade ranging from the metastasis initiation to colonization. Then we reviewed current approaches of targeting these factors to stifle the metastatic cascade, including modulating primary tumor microenvironment, targeting circulating tumor cells, regulating premetastatic niche and eliminating established metastasis. Additionally, we highlighted the multi-phase targeted drug delivery systems, which hold a better chance to inhibit metastasis. Besides, we demonstrated the limitation and future perspectives of nanomedicine-based anti-metastasis strategies.

Role of myeloid-derived suppressor cells in premetastatic niche formation and tumor metastasis promotion / 中国癌症杂志

Sustaining survival of tumor cells is the main limiting step of tumor metastasis. Similar to tumor microenvironment, local environment in premetastatic organ (premetastatic niche) also provides a favorable condition for surviving of tumor cell and is the premise of tumor cell survival and proliferation in distant organ. Myeloid-derived suppressor cells (MDSCs) are the key component of the niche and play an important role in tumor cell implantation and metastasis formation through fabricating a proliferative, inflammatory, immunosuppressive and vascular remodeling premetastatic niche. MDSCs may also serve as potential therapeutic target for anti-metastasis therapy. Here, this study focused on the mechanisms of MDSCs in prematastatic niche formation and associated signal pathway, moreover, pro-vided reference to study on anti-metastasis therapy through interfering with the formation of premetastatic niche.