A novel EGFP-expressing nude mice with complete loss of lymphocytes and NK cells to study tumor-host interactions

[Peripheral blood exosomes from patients with multiple myeloma mediate bortezomib resistance in cultured multiple myeloma cells]

OBJECTIVE

To investigate the role of exosome in mediating bortezomib (Btz) resistance in multiple myeloma cells in vitro and explore the underlying mechanisms.

METHODS

Peripheral blood samples were collected from 15 patients with multiple myeloma with Btz tolerance, and serum exosomes were isolated by ultracentrifugation and identified with electron microscopy, NTA and Western blotting. In vitro cultured multiple myeloma cells were treated with gradient concentrations of Btz to determine the optimal drug concentration for subsequent experiment. The cells were pretreated with different concentrations of exosomes, and their sensitivity to BTZ was assessed using MTS assay. We searched the exosome database Exocarta and used STRING to generate the network map and the protein interaction graph.

RESULTS

The diameters of the vesicles isolated from the peripheral blood of the patients were mostly below 200 nm with a mean particle size of 153 nm and a mode of 140.1 nm. The results of Western blotting showed that the isolated exosomes expressed the marker proteins CD63, Tsg101 and Alix. In cultured multiple myeloma cells, pretreatment with exosomes resulted in a decreased sensitivity of the cells to bortezomib, and longer treatment durations and higher exosome concentrations consistently enhanced the resistance of the cells to the same Btz concentration. Analysis of the Exocarta database identified human serum exosomal proteins ABCB1, ABCB4, PDCD6IP, and EGFR, among which EGFR served as a network node.

CONCLUSIONS

Exosome within a specific concentration range may serve as a signal carrier to mediate the resistance of multiple myeloma cells to Btz. EGFR likely plays a key role to promote exosome-mediated Btz resistance in myeloma cells.

Application of Highly Immunocompromised Mice for the Establishment of Patient-Derived Xenograft (PDX) Models

Patient-derived xenograft (PDX) models are created by engraftment of patient tumor tissues into immunocompetent mice. Since a PDX model retains the characteristics of the primary patient tumor including gene expression profiles and drug responses, it has become the most reliable in vivo human cancer model. The engraftment rate increases with the introduction of Non-obese diabetic Severe combined immunodeficiency (NOD/SCID)-based immunocompromised mice, especially the NK-deficient NOD strains NOD/SCID/interleukin-2 receptor gamma chain(IL2Rγ)null (NOG/NSG) and NOD/SCID/Jak3(Janus kinase 3)null (NOJ). Success rates differ with tumor origin: gastrointestinal tumors acquire a higher engraftment rate, while the rate is lower for breast cancers. Subcutaneous transplantation is the most popular method to establish PDX, but some tumors require specific environments, e.g., orthotropic or renal capsule transplantation. Human hormone treatment is necessary to establish hormone-dependent cancers such as prostate and breast cancers. PDX mice with human hematopoietic and immune systems (humanized PDX) are powerful tools for the analysis of tumor-immune system interaction and evaluation of immunotherapy response. A PDX biobank equipped with patients' clinical data, gene-expression patterns, mutational statuses, tumor tissue architects, and drug responsiveness will be an authoritative resource for developing specific tumor biomarkers for chemotherapeutic predictions, creating individualized therapy, and establishing precise cancer medicine.

Tumorigenicity and Validity of Fluorescence Labelled Mesenchymal and Epithelial Human Oral Cancer Cell Lines in Nude Mice

Tumorigenicity and metastatic activity can be visually monitored in cancer cells that were labelled with stable fluorescence. The aim was to establish and validate local and distant spread of subcutaneously previously injected fluorescence transduced human tongue cancer cell lines of epithelial and mesenchymal phenotype in nude mice. A total of 32 four-week-old male athymic Balb/c nude mice were randomly allocated into 4 groups (n = 8). A single dose of 0.3 mL PBS containing 1 × 107 of four different cancer cell-lines (UM1, UM1-GFP, UM2, and UM2-RFP) was injected subcutaneously into the right side of their posterolateral back. Validity assessment of the labelled cancer cells' tumorigenicity was assessed by physical examination, imaging, and histology four weeks after the injection. The tumor take rate of cancer cells was similar in animals injected with either parental or transduced cancer cells. Transduced cancer cells in mice were easily detectable in vivo and after cryosection using fluorescent imaging. UM1 cells showed increased tumor take rate and mean tumor volume, presenting with disorganized histopathological patterns. Fluorescence labelled epithelial and mesenchymal human tongue cancer cell lines do not change in tumorigenicity or cell phenotype after injection in vivo.

Inhibition of carbonic anhydrase potentiates bevacizumab treatment in cholangiocarcinoma

Cholangiocarcinoma (CCA) is a unique liver cancer subtype with an increasing incidence globally. The lack of specific symptoms and definite diagnostic markers results in a delayed diagnosis and disease progression. Systemic chemotherapy is commonly selected for advanced CCA even though its advantages remain unknown. Targeted therapy, especially anti-vascular endothelial growth factor (VEGF) therapy, is promising for CCA; however, improvements in the therapeutic regimen are necessary to overcome subsequent resistance. We demonstrated VEGF expression was higher in CCA cell lines than in other liver cancer cells. Secreted VEGFs played roles in the induction of peri- and intra-tumoral vascularization. VEGF neutralization by bevacizumab effectively reduced tumor growth, mainly through the suppression of angiogenesis; however, increases in the expression of hypoxia-inducible factor 1α (HIF1α) and HIF1α-responsive genes (such as VEGF, VEGFR1, VEGFR2, carbonic anhydrase (CA) IX and CAXII) indicated the potential for subsequent therapeutic resistance. Supplementation with a carbonic anhydrase inhibitor, acetazolamide, enhanced the anti-CCA effects of bevacizumab. Anti-angiogenesis and anti-proliferation were observed with the combination treatment. These results suggested a novel treatment strategy to overcome anti-angiogenesis resistance and the importance of "induced essentiality" in the treatment of CCA.