Quantitative and Functional Requirements for Bioluminescent Cancer Models.

BACKGROUND: Bioluminescent cancer models are widely used but detailed quantification of the luciferase signal and functional comparison with a non-transfected control cell line are generally lacking. In the present study, we provide quantitative and functional tests for luciferase-transfected cells. MATERIALS AND METHODS: We quantified the luciferase expression in BLM and HCT8/E11 transfected cancer cells, and examined the effect of long-term luciferin exposure. The present study also investigated functional differences between parental and transfected cancer cells. RESULTS: Our results showed that quantification of different single-cell-derived populations are superior with droplet digital polymerase chain reaction. Quantification of luciferase protein level and luciferase bioluminescent activity is only useful when there is a significant difference in copy number. Continuous exposure of cell cultures to luciferin leads to inhibitory effects on mitochondrial activity, cell growth and bioluminescence. These inhibitory effects correlate with luciferase copy number. Cell culture and mouse xenograft assays showed no significant functional differences between luciferase-transfected and parental cells. CONCLUSION: Luciferase-transfected cells should be validated by quantitative and functional assays before starting large-scale experiments.

FHL2: a scaffold protein of carcinogenesis, tumour-stroma interactions and treatment response.

Four-and-a-half LIM-domain protein 2 (FHL2) is a multifunctional scaffolding protein regulating signalling cascades and gene transcription. It shuttles between focal adhesions and the nucleus where it signals through direct interaction with a number of proteins including ß-catenin. The multiplicity of molecular pathways affected by FHL2 suggests an important role in several physiological and pathological events. The function of FHL2 in cancer is particularly intriguing, since it may act as an oncoprotein or as a tumour suppressor in a tissue-dependent fashion. In this review we present the current knowledge on the role of FHL2 in carcinogenesis, with emphasis on the digestive tract. We discuss the overexpression of FHL2 in colorectal, gastric and pancreatic cancer, the downregulation in hepatocellular carcinoma and the role of FHL2 in epithelial-mesenchymal transition. We briefly look at the potential role of FHL2 in the tumoural microenvironment and discuss how FHL2 expression and function might influence cancer treatment. Before implementation of FHL2 as a biomarker by pathologists, antibody validation should, however, be carried out.

Radiation-induced lung damage promotes breast cancer lung-metastasis through CXCR4 signaling.

Radiotherapy is a mainstay in the postoperative treatment of breast cancer as it reduces the risks of local recurrence and mortality after both conservative surgery and mastectomy. Despite recent efforts to decrease irradiation volumes through accelerated partial irradiation techniques, late cardiac and pulmonary toxicity still occurs after breast irradiation. The importance of this pulmonary injury towards lung metastasis is unclear. Preirradiation of lung epithelial cells induces DNA damage, p53 activation and a secretome enriched in the chemokines SDF-1/CXCL12 and MIF. Irradiated lung epithelial cells stimulate adhesion, spreading, growth, and (transendothelial) migration of human MDA-MB-231 and murine 4T1 breast cancer cells. These metastasis-associated cellular activities were largely mimicked by recombinant CXCL12 and MIF. Moreover, an allosteric inhibitor of the CXCR4 receptor prevented the metastasis-associated cellular activities stimulated by the secretome of irradiated lung epithelial cells. Furthermore, partial (10%) irradiation of the right lung significantly stimulated breast cancer lung-specific metastasis in the syngeneic, orthotopic 4T1 breast cancer model.Our results warrant further investigation of the potential pro-metastatic effects of radiation and indicate the need to develop efficient drugs that will be successful in combination with radiotherapy to prevent therapy-induced spread of cancer cells.

P-cadherin expression reduces melanoma growth, invasion, and responsiveness to growth factors in nude mice.

The prognostic discrepancy between localized melanoma and metastatic disease demands a better understanding of melanoma progression. The role of E-cadherin and N-cadherin in melanoma has been widely studied; however, the function of P-cadherin remains to be elucidated. We wanted to assess the effects of P-cadherin overexpression in BLM melanoma cells with regard to xenograft growth, invasion, and survival of mice in our model to mimic micrometastatic spread. Swiss nu/nu mice were subcutaneously injected with control (BLM LIE) and P-cadherin overexpressing (BLM P-cad) melanoma cells alone and in combination with myofibroblasts, and intracardially injected with BLM LIE and BLM P-cad cells. Tumor volumes and survival of mice were assessed and analyzed. In-vitro assays were used to further investigate the influence, and identify the target receptors of growth factors secreted by myofibroblasts in melanoma cells. In-vivo experiments point out that P-cadherin reduces xenograft growth (1621 mm ± 107 vs. 329 mm ± 71) and invasion, and prolongs overall survival (34.1 ± 0.84 vs. 51.1 ± 1.8 days) of mice in our model to mimic micrometastatic spread. Coinjection with myofibroblasts resulted in increased tumor growth in BLM LIE (3896 mm ± 64 vs. 1621 mm ± 107) in contrast to BLM P-cad (417 mm ± 47 vs. 329 ± 71). P-cadherin reduces melanoma growth and invasion, prolongs the survival of mice intracardially injected, and induces a state of decreased responsiveness to myofibroblast-derived growth factors. Therefore, P-cadherin can be considered as a potential therapeutic target in the treatment of melanoma.