Tumor-associated Macrophages (TAMs) in Cancer Resistance; Modulation by Natural Products.

Tumor-associated macrophages (TAMs) play a pivotal role in the progression and resistance of tumors to different anticancer drugs. TAMs can modulate the tumor microenvironment (TME) in favor of immune system exhaustion. The interactions of TAMs with TME can affect the function of cytotoxic CD8+ T lymphocytes (CTLs) and natural killer (NK) cells. Furthermore, TAMs can induce cancer cell proliferation by releasing some growth factors, such as transforming growth factor (TGF)-ß. TAMs have several positive cross-talks with other immune suppressive cells such as regulatory T cells (Tregs), myeloid-derived suppressor cells (MDSCs), cancerassociated fibroblasts (CAFs), and cancer cells, leading to the release of growth factors, the proliferation of cancer cells and tumor growth. These interactions also can induce invasion and migration of cancer cells, angiogenesis, and metastasis. The inhibition of TAMs is an intriguing strategy for overcoming tumor resistance and suppression of cancer cells. Some natural-derived agents such as melatonin, curcumin, resveratrol, apigenin, and other flavonoids have shown the ability to modulate TME, including TAMs. These adjuvants may be able to boost antitumor immunity through the modulation of TAMs. This review explains the modulatory effects of some well-known naturally derived agents on the activity of TAMs. The modulation of TAMs by these agents may be useful in suppressing tumor growth and invasion.

Utilization of novel lectin-conjugated Au nanoparticles as Thomsen-Friedenreich onco-antigen target for in vitro cytotoxicity and apoptosis induction in leukemic cell line.

Leukemia is a tumor of blood-forming tissues including bone marrow and lymphatic nodes, which comprise biologically distinct subgroups. In the present study, Au NPs-PEG-Lectin was prepared as a drug targeting system for potential Thomsen-Friedenreich antigen (TF-Ag) presented on the surface of leukemic cells to induce cytotoxicity. Gold nanoparticles were prepared using citrate reduction method and conjugated with lectin via SH-PEG-COOH. The conjugate was characterized using UV/Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Zeta potential, and Scanning electron microscopy (SEM) with subsequent applications for cytotoxicity, cell cycle analysis, and apoptosis. Immunophenotypically blood samples from patients with acute lymphoblastic leukemia (ALL) were positively expressed CD45, CD95 dim expression, and low CD176 (TF-Ag) expression. Samples of acute myeloid leukemia (AML) confirmed the expression of all markers. Au NPs-PEG-Lectin conjugate showed an average size of 35.82 nm with zeta potential of -27.33 with accelerated lectin release from the conjugate at acidic pH. Au NPs-PEG-Lectin demonstrated the highest and most significant cytotoxic activity against HL-60 and K562 with IC50 of 132.5 and 314.8 µg mL-1, respectively. Flow cytometric analysis revealed induction of HL-60 cell apoptosis upon conjugate treatment in a dose-dependent pattern up to 51.03 % with no sign of necrosis with cell cycle arrest at G0/G1 phase. HL-60 cells treated with Au NPs-PEG-Lectin exhibited inter-nucleosomal DNA fragmentation. Morphologically, Phospho-Histone/BrdU dual staining indicated that Au NPs-PEG-Lectin initiated HL-60 arrest at G0/G1 phase. Taken together, molecular docking verified the possible interaction between lectin amino acids and different hydroxy groups within TF-Ag forming hydrogen bonds.