Human mesenchymal stromal cells (hMSCs) show great potential for clinical and experimental use due to their capacity to self-renew and differentiate into multiple mesenchymal lineages. However, disadvantages of primary cultures of hMSCs are the limited in vitro lifespan, and the variable properties of cells from different donors and over time in culture. In this article, we describe the generation of a telomerase-immortalized nontumorigenic human bone marrow-derived stromal mesenchymal cell line, and its detailed characterization after long-term culturing (up to 155 population doublings). The resulting cell line, iMSC#3, maintained a fibroblast-like phenotype comparable to early passages of primary hMSCs, and showed no major differences from hMSCs regarding surface marker expression. Furthermore, iMSC#3 had a normal karyotype, and highresolution array comparative genomic hybridization confirmed normal copy numbers. The gene expression profiles of immortalized and primary hMSCs were also similar, whereas the corresponding DNA methylation profiles were more diverse. The cells also had proliferation characteristics comparable to primary hMSCs and maintained the capacity to differentiate into osteoblasts and adipocytes. A detailed characterization of the mRNA and microRNA transcriptomes during adipocyte differentiation also showed that the iMSC#3 recapitulates this process at the molecular level. In summary, the immortalized mesenchymal cells represent a valuable model system that can be used for studies of candidate genes and their role in differentiation or oncogenic transformation, and basic studies of mesenchymal biology.
The tumor microenvironment (TME) may influence both cancer progression and therapeutic response. In breast cancer, particularly in the aggressive triple‐negative/basal‐like subgroup, patient outcome is strongly associated with the tumor's inflammatory profile. Tumor‐associated macrophages (TAMs) are among the most abundant immune cells in the TME, shown to be linked to poor prognosis and therapeutic resistance. In this study, we investigated the effect of the metastasis‐ and inflammation‐associated microenvironmental factor S100A4 on breast cancer cells (BCCs) of different subtypes and explored their further interactions with myeloid cells. We demonstrated that extracellular S100A4 activates BCCs, particularly the basal‐like subtype, to elevate secretion of pro‐inflammatory cytokines. The secreted factors promoted conversion of monocytes to TAM‐like cells that exhibited protumorigenic activities: stimulated epithelial–mesenchymal transition, proliferation, chemoresistance, and motility in cancer cells. In conclusion, we have shown that extracellular S100A4 instigates a tumor‐supportive microenvironment, involving a network of cytokines and TAM‐like cells, which was particularly characteristic for basal‐like BCCs and potentiated their aggressive properties. The S100A4–BCC–TAM interaction cascade could be an important contributor to the aggressive behavior of this subtype and should be further explored for therapeutic targeting.
Wee1 is a nuclear kinase regulating cell cycle progression, and has emerged as a promising therapeutic target in cancer. Expression of Wee1 has been associated with poor outcome in certain tumor types, but the prognostic impact and clinical significance in colorectal cancer is unknown. The expression of Wee1 was examined by immunohistochemistry in primary colorectal carcinomas from a prospectively collected patient cohort, and associations with clinicopathological parameters and outcome were investigated. Cell culture experiments were performed using the cell lines RKO and SW620, and the relationship with the metastasis-promoting protein S100A4 was investigated. Nuclear expression was detected in 229 of the 258 tumors analyzed (89 %). Wee1 staining was associated with low pT stage, but no other significant associations with demographic or histopathological variables were found. Moderate Wee1 staining intensity was a predictor of favorable metastasis-free and overall survival compared to strong intensity and no or weak staining. The fraction of positive cells was not a prognostic factor in the present cohort. Inhibition of Wee1 expression using siRNA or treatment with the Wee1 inhibitor MK-1775 reduced expression of the metastasis-promoting protein S100A4, but no relationship between Wee1 and S100A4 was found in the patient samples. In conclusion, Wee1 is highly expressed in primary colorectal carcinomas, but few relevant associations with clinicopathological parameters or outcome were found. The lack of clinical significance of Wee1 expression could indicate that other tumor types might be better suited for further development of Wee1 inhibitors.
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