Macrophage infiltration in 3D cancer spheroids to recapitulate the TME and unveil interactions within cancer cells and macrophages to modulate chemotherapeutic drug efficacy

BACKGROUND

Recapitulating the tumor microenvironment (TME) in vitro remains a major hurdle in cancer research. In recent years, there have been significant strides in this area, particularly with the emergence of 3D spheroids as a model system for drug screening and therapeutics development for solid tumors. However, incorporating macrophages into these spheroid cultures poses specific challenges due to the intricate interactions between macrophages and cancer cells.

METHODS

To address this issue, in this study, we established a reproducible healthy multicellular 3D spheroid culture with macrophage infiltrates in order to mimic the TME and modulate the drug's efficacy on cancer cells in the presence of macrophages. A 3D spheroid was established using the human cancer cell line CAL33 and THP1 cell derived M0 macrophages were used as a source of macrophages. Cellular parameters including tumour metabolism, health, and mitochondrial mass were analysed in order to establish ideal conditions. To modulate the interaction of cancer cells with macrophage the ROS, NO, and H2O2 levels, in addition to M1 and M2 macrophage phenotypic markers, were analyzed. To understand the crosstalk between cancer cells and macrophages for ECM degradation, HSP70, HIF1α and cysteine proteases were examined in spheroids using western blotting and qPCR.

RESULTS

The spheroids with macrophage infiltrates exhibited key features of solid tumors, including cellular heterogeneity, metabolic changes, nutrient gradients, ROS emission, and the interplay between HIF1α and HSP70 for upregulation of ECM degradading enzymes. Our results demonstrate that tumor cells exhibit a metabolic shift in the presence of macrophages. Additionally, we have observed a shift in the polarity of M0 macrophages towards tumor-associated macrophages (TAMs) in response to cancer cells in spheroids. Results also demonstrate the involvement of macrophages in regulating HIF-1α, HSP70, and ECM degradation cysteine proteases enzymes.

CONCLUSIONS

This study has significant implications for cancer therapy as it sheds light on the intricate interaction between tumor cells and their surrounding macrophages. Additionally, our 3D spheroid model can aid in drug screening and enhance the predictive accuracy of preclinical studies. The strength of our study lies in the comprehensive characterization of the multicellular 3D spheroid model, which closely mimics the TME.

A benzophenanthridine alkaloid, chelerythrine induces apoptosis in vitro in a Dalton's lymphoma

PURPOSE

The aim of this study was to investigate the effect of chelerythrine on DL cell apoptosis in an in vitro experimental setup.

MATERIALS AND METHODS

For tumor model, spontaneous occurring T-cell lymphoma designated as Dalton's lymphoma (DL) was selected. Double staining, transmission electron microscope (TEM), fluorescence microscopy, Western blotting, Reverse Transcriptase-Polymerase Chain Reaction, and DNA fragmentation assay were used to detect heat shock factor 1 (HSF1) and hsp70 expression and PKC phosphorylation, and apoptotic characteristic of DL cells.

RESULTS

Chelerythrine exposure resulted in significant morphological alteration comparable to that of apoptosis. Furthermore, it was confirmed by fluorescence microscopy, TEM analysis, and DNA fragmentation assay that 10 μg/mL of chelerythrine is capable of inducing apoptosis in DL cells. The suppression in HSF1 expression and subsequent inhibition of hsp70 expression in chelerythrine-treated DL cells suggest that chelerythrine induces apoptosis in DL cells by inhibiting the expression of these cytoprotective proteins.

CONCLUSION

Chelerythrine is capable of inducing apoptosis DL cells in vitro and therefore, it could be useful in combating tumor growth and progression.

Suppressed expression of homotypic multinucleation, extracellular domains of CD172α (SIRP-α) and CD47 (IAP) receptors in TAMs upregulated by Hsp70-peptide complex in Dalton's lymphoma

CD172α and CD47 are members of glycoprotein expressed on macrophages and various immune cells, promote immune recognition and T cell stimulation that priming phagocytosis of pathogens and apoptotic bodies and malignant cell. Tumour-releasing immunosuppressive factor promotes tumour growth and transforms the tumour resident M1 phenotype of macrophage to M2 phenotype (TAMs) that promotes tumour progression by downregulating the expression of different surface receptor including CD172α and CD47. Recent studies have reported that CD172α and CD47 are involved in the pathogenesis and promote malignancies such as lymphoma, leukaemia, melanoma, lung cancer and multiple myeloma, and their expression varies during infection and malignancies. Autologous Hsp70 is well recognized for its role in activating macrophages leading to enhance production of inflammatory cytokines. It has been observed that Hsp70 derived from normal tissues do not elicit tumour immunity, while Hsp70 preparation from tumour cell was able to elicit tumour immunity. However, the role of exogenous autologous hsp70 on the formation of giant cells is completely unknown. Therefore, in the present study, we sought to investigate the effect of Hsp70-peptide complex on the expression of CD172α and CD47 receptors in normal peritoneal macrophages (NMO) and TAMs. Finding shows that the expression of CD172α and CD47 enhances in TAMs and it reverts back the suppressed function of TAMs into M1 state of immunoregulatory phenotype that promotes tumour regression by enhanced multinucleation and phagocytosis of malignant cells and significantly enhances the homotypic fusion of macrophages and polykaryon formation in vitro by enhancing the expression of SIRPα and IAP.