TABLE 2.
Mechanisms of antitumor drug resistance mediated by TAMs.
| Tumor type | Drug resistance | Mechanisms | References |
| Breast cancer | Paclitaxel | TAMs secreting cathepsins B and S. | Shree et al., 2011 |
| Cyclopamine | TAMs increasing the production of IL-6. | Xu X. et al., 2019 | |
| Paclitaxel | TAMs secreting IL-10, activating STAT3 and elevating the expression of Bcl-2. | Yang et al., 2015 | |
| CRC | 5-FU | TAMs secreting putrescine that inhibits the activation of JNK/caspase-3 pathway. | Zhang et al., 2016 |
| Oxaliplatin | TAMs secreting IL-6, activating IL-6R/STAT3/miR-204-5p pathway of tumor cells. | Yin et al., 2017 | |
| Cisplatin | TAMs secreting MFG-E8 to regulate CSCs via activating STAT3 and hedgehog signal. | Jinushi et al., 2011 | |
| Gastric cancer | Cisplatin | TAMs producing exosomes containing miR-21, downregulating PTEN and enhancing PI3K/AKT. | Zheng et al., 2017 |
| Glioma | Cisplatin | TAMs producing NO, inhibiting acid sphingomyelinase via NO/cGMp/PKA pathway. | Perrotta et al., 2018 |
| Anti-PD-L1/CTLA-4 | PD-L1 of TAMs binding with CD80 of CD4+ T cells, inhibiting antitumor T cell responses. | Aslan et al., 2020 | |
| HCC | Anti-PD-L1 | TREM-1+ TAMs damaging the cytotoxic functions of CD8+ T cells and causing CD8+ T cell apoptosis. | Wu et al., 2019 |
| HNSCC | Gefitinib | TAMs secreting CCL15, activating CCL15/CCR1/NF-κB pathway. | Yin et al., 2019 |
| Ovarian cancer | Cisplatin | TAMs secreting exosomes delivering miR-223, inactivating PI3K/AKT signal by targeting PTEN. | Zhu et al., 2019 |
| Pancreatic cancer | Gemcitabine | TAM secreting pyrimidines competitively inhibits gemcitabine uptake and metabolism. | Halbrook et al., 2019 |
| Gemcitabine | TAMs upregulating cytidine deaminase, promoting drug degradation. | Weizman et al., 2014 | |
| Gemcitabine | TAMs derived-exosomes transfer miR-365, upregulating cytidine deaminase. | Binenbaum et al., 2018 | |
| Camptothecin | TAMs secreting IL-1β, promoting the production of COX-2 and PGE2 via ERK1/2. | Angst et al., 2008 | |
| 5-FU | TAMs inducing EMT. | Kuwada et al., 2018 | |
| Prostate cancer | ADT | TAMs enhancing the stem-like properties of CSCs via IL-6/STAT3 pathway. | Huang et al., 2018 |
CRC, colorectal cancer; HCC, hepatocellular carcinoma; HNSCC, head and neck squamous cell carcinoma; 5-FU, 5-fluorouracil; ADT, androgen deprivation therapy; EMT, epithelial-mesenchymal transition.