bims-stacyt 2021-10-10 papers

Front Immunol. 2021 ;12 741305

Tumor-Associated Macrophages and Their Functional Transformation in the Hypoxic Tumor Microenvironment.

Tumor-associated macrophages (TAMs) are some of the most abundant immune cells within tumors and perform a broad repertoire of functions via diverse phenotypes. On the basis of their functional differences in tumor growth, TAMs are usually categorized into two subsets of M1 and M2. It is well established that the tumor microenvironment (TME) is characterized by hypoxia along with tumor progression. TAMs adopt an M1-like pro-inflammatory phenotype at the early phases of oncogenesis and mediate immune response that inhibits tumor growth. As tumors progress, anabatic hypoxia of the TME gradually induces the M2-like functional transformation of TAMs by means of direct effects, metabolic influence, lactic acidosis, angiogenesis, remodeled stroma, and then urges them to participate in immunosuppression, angiogenesis and other tumor-supporting procedure. Therefore, thorough comprehension of internal mechanism of this TAM functional transformation in the hypoxic TME is of the essence, and might provide some novel insights in hypoxic tumor immunotherapeutic strategies.

Keywords: hypoxic tumor microenvironment; macrophage functional transformation; macrophage polarization; tumor hypoxia; tumor-associated macrophages

DOI: https://doi.org/10.3389/fimmu.2021.741305

Trends Immunol. 2021 Oct 02. pii: S1471-4906(21)00178-2. [Epub ahead of print]

Metabolic regulation of the cancer-immunity cycle.

Luis F Somarribas Patterson, Santosha A Vardhana.

The cancer-immunity cycle (CIC) comprises a series of events that are required for immune-mediated control of tumor growth. Interruption of one or more steps of the CIC enables tumors to evade immunosurveillance. However, attempts to restore antitumor immunity by reactivating the CIC have had limited success thus far. Recently, numerous studies have implicated metabolic reprogramming of tumor and immune cells within the tumor microenvironment (TME) as key contributors to immune evasion. In this opinion, we propose that alterations in cellular metabolism during tumorigenesis promote both initiation and disruption of the CIC. We also provide a rationale for metabolically targeting the TME, which may assist in improving tumor responsiveness to chimeric antigen receptor (CAR)-transduced T cells or immune checkpoint blockade (ICB) therapies.

Keywords: CAR-T cells; PD-1; glycolysis; immunotherapy; lactate; metabolism; tumor immunology

DOI: https://doi.org/10.1016/j.it.2021.09.002

Endocrinology. 2021 Oct 06. pii: bqab212. [Epub ahead of print]

TXNIP links anticipatory unfolded protein response to estrogen reprogramming glucose metabolism in breast cancer cells.

Yuanzhong Wang, Shiuan Chen.

Estrogen and estrogen receptor (ER) play a fundamental role in breast cancer. To adapt the rapid proliferation of ER+ breast cancer cells, estrogen increases glucose uptake and reprograms glucose metabolism. Meanwhile, estrogen/ER activates the anticipatory unfolded protein response (UPR) preparing cancer cells for the increased protein production required for subsequent cell proliferation. Here, we report that thioredoxin-interacting protein (TXNIP) is an important regulator of glucose metabolism in ER+ breast cancer cells, and estrogen/ER increases glucose uptake and reprograms glucose metabolism via activating anticipatory unfolded protein response (UPR) and subsequently repressing TXNIP expression. By using two widely used ER+ breast cancer cell lines MCF7 and T47D, we showed that MCF7 cells express high TXNIP levels and exhibit mitochondrial oxidative phosphorylation (OXPHOS) phenotype, while T47D cells express low TXNIP levels and display aerobic glycolysis (Warburg effect) phenotype. Knockdown of TXNIP promoted glucose uptake and Warburg effect, while forced overexpression of TXNIP inhibited glucose uptake and Warburg effect. We further showed that estrogen represses TXNIP expression and activates UPR sensor inositol-requiring enzyme 1 (IRE1) via ER in the breast cancer cells, and IRE1 activity is required for estrogen suppression of TXNIP expression and estrogen-induced cell proliferation. Together, our study suggests that TXNIP is involved in estrogen-induced glucose uptake and metabolic reprogramming in ER+ breast cancer cells, and links anticipatory UPR to estrogen reprogramming glucose metabolism.

Keywords: TXNIP; breast cancer; estrogen; glucose metabolism; unfolded protein response

DOI: https://doi.org/10.1210/endocr/bqab212