Editorial: The adipose tissue microenvironment in cancer: Molecular mechanisms and targets for treatment

The adipose tissue microenvironment in cancer: Molecular mechanisms and targets for treatment Adipose tissue is one of the major components distributed throughout the human body and is considered as tissues that actively participates in metabolic and endocrine homeostasis.Cancer-associated adipocytes (CAAs) are commonly seen in tumors that originate from adipocyte-rich organs, which include breast cancer, ovarian cancer, colorectal cancer, and pancreatic cancers.Though CAAs were originally thought to be merely a passive, neutral, and terminally differentiated cell type during tumor progression, interest in them re-surged after they were identified to have multiple abilities to promote tumor growth, invasion, and metastasis.Recent evidence shows that CAAs respond to cancer cell-derived paracrine signaling to provide various adipokines, growth factors, as well as metabolic substrates for enhancing tumor cell proliferation and invasion (Quail and Dannenberg, 2019;Hoy et al., 2017).In addition to direct crosstalk between CAA and tumor cells, CAA participates in TME remodeling by altering the phenotype of other host cell types or by the phenotypic transition to fibroblast-like cells (Bochet et al., 2013).The remodeled TME in turn facilitates tumor growth, invasion, and drug resistance (Song et al., 2020;Iwamoto et al., 2018;Sheng et al., 2017).This indirect tumor-promoting effect of CAA has not been fully understood.Other than adipocytes in the tumor, distant adipose depots outside the TME restlessly communicate with tumor tissue.Factors and metabolites released from the TME influence the distant tissues and organs, hence inducing cancer-associated complications.Cancer-associated cachexia (CAC) is the most critical cancerassociated complication and is estimated to be the cause of death in 1/4 of cancer patients (Baracos et al., 2018).Conversely, distant adipose depots provide metabolites, endocrine factors, and exosomes to regulate tumor development (Jafari et al., 2021).Together, adipocyte-tumor cell crosstalk not only happens in