The possibility to combine Low Intensity UltraSound (LIUS) and Nanoparticles (NP) could represent a promising strategy for drugs delivery in tumors difficult to treat overcoming resistance to therapies. On one side the NP can carry drugs that specifically target the tumors on the other the LIUS can facilitate and direct the delivery to the tumor cells. In this study, we investigated whether Very Low Intensity UltraSound (VLIUS), at intensities lower than 120 mW/cm2, might constitute a novel strategy to improve delivery to tumor cells. Thus, in order to verify the efficacy of this novel modality in terms of increase selective uptake in tumoral cells and translate speedily in clinical practice, we investigated VLIUS in three different in vitro experimental tumor models and normal cells adopting three different therapeutic strategies. VLIUS at different intensities and exposure time were applied to tumor and normal cells to evaluate the efficiency in uptake of labeled human ferritin (HFt)-based NP, the delivery of NP complexed Firefly luciferase reported gene (lipoplex-LUC), and the tumor-killing of chemotherapeutic agent. Specifically, we found that specific VLIUS intensity (120 mW/cm2) increases tumor cell uptake of HFt-based NPs at specific concentration (0.5 mg/ml). Similarly, VLIUS treatments increase significantly tumor cells delivery of lipoplex-LUC cargos. Furthermore, of interest, VLIUS increases tumor killing of chemotherapy drug trabectedin in a time dependent fashion. Noteworthy, VLIUS treatments are well tolerated in normal cells with not significant effects on cell survival, NPs delivery and drug-induced toxicity, suggesting a tumor specific fashion. Our data shed novel lights on the potential application of VLIUS for the design and development of novel therapeutic strategies aiming to efficiently deliver NP loaded cargos or anticancer drugs into more aggressive and unresponsive tumors niche.

Obesity confers risks to cancer development and progression but the mechanisms underlying these risks remain unclear. In this study, we identify a role for the obesity cytokine leptin, which has been implicated previously in breast cancer development, as a determinant for the tumor-promoting activity of cancer-associated fibroblasts (CAF) in both wild-type (WT) and K303R mutant estrogen receptor-α (ERα)–expressing breast cancer cells. Human CAFs stimulated a greater increase in the proliferation and migration of breast cancer cells expressing the K303R-ERα hyperactive receptor than WT-ERα–expressing cells. A concomitant increase was seen in leptin receptor isoform expression and activation of the leptin signaling pathway in cells expressing K303R-ERα compared with WT-ERα, correlating with leptin effects on cell growth, motility, and invasiveness in mutant cells. Epidermal growth factor and other factors secreted by K303R-ERα cells stimulated CAF proliferation, migration, and subsequent leptin secretion. Moreover, K303R-ERα expression generated a leptin hypersensitive phenotype in vivo. Together, our results reveal a bidirectional cross-talk between breast cancer cells and “educated” CAFs that drives tumor progression via leptin signaling. In elucidating a mechanism that connects obesity and cancer, these findings reinforce the concept that blocking cancer–stromal cell communication may represent an effective strategy for targeted therapy of breast cancer. Cancer Res; 72(6); 1416–27. ©2012 AACR.

Preclinical in vivo studies using small animals are considered crucial in translational cancer research and clinical implementation of novel treatments. This is of paramount relevance in radiobiology, especially for any technological developments permitted to deliver high doses in single or oligo-fractionated regimens, such as stereotactic ablative radiotherapy (SABR). In this context, clinical success in cancer treatment needs to be guaranteed, sparing normal tissue and preventing the potential spread of disease or local recurrence. In this work we introduce a new dose-response relationship based on relevant publications concerning preclinical models with regard to delivered dose, fractionation schedule and occurrence of biological effects on non-irradiated tissue, abscopal effects. We reviewed relevant publications on murine models and the abscopal effect in radiation cancer research following PRISMA methodology. In particular, through a log-likelihood method, we evaluated whether the occurrence of abscopal effects may be related to the biologically effective dose (BED). To this aim, studies accomplished with different tumor histotypes were considered in our analysis including breast, colon, lung, fibrosarcoma, pancreas, melanoma and head and neck cancer. For all the tumors, the α / β ratio was assumed to be 10 Gy, as generally adopted for neoplastic cells. Our results support the hypothesis that the occurrence rate of abscopal effects in preclinical models increases with BED. In particular, the probability of revealing abscopal effects is 50% when a BED of 60 Gy is generated. Our study provides evidence that SABR treatments associated with high BEDs could be considered an effective strategy in triggering the abscopal effect, thus shedding light on the promising outcomes revealed in clinical practice.

The involvement of p53 protein in cell differentiation has been recently suggested by some observations made with tumor cells and the correlation found between differentiation and increased levels of p53. However, the effect of p53 on differentiation is in apparent contrast with the normal development of p53-null mice. To test directly whether p53 has a function in cell differentiation, we interfered with the endogenous wt-p53 protein of nontransformed cells of two different murine histotypes: 32D myeloid progenitors, and C2C12 myoblasts. A drastic inhibition of terminal differentiation into granulocytes or myotubes, respectively, was observed upon expression of dominant-negative p53 proteins. This inhibition did not alter the cell cycle withdrawal typical of terminal differentiation, nor p21(WAF1/CIP1) upregulation, indicating that interference with endogenous p53 directly affects cell differentiation, independently of the p53 activity on the cell cycle. We also found that the endogenous wt-p53 protein of C2C12 cells becomes transcriptionally active during myogenesis, and this activity is inhibited by p53 dominant-negative expression. Moreover, we found that p53 DNA-binding and transcriptional activities are both required to induce differentiation in p53-negative K562 cells. Taken together, these data strongly indicate that p53 is a regulator of cell differentiation and it exerts this role, at least in part, through its transcriptional activity.

Leptin, a cytokine mainly produced by adipocytes, seems to play a crucial role in mammary carcinogenesis. In the present study, we explored the mechanism of leptin-mediated promotion of breast tumor growth using xenograft MCF-7 in 45-day-old female nude mice, and an in vitro model represented by MCF-7 three-dimensional cultures. Xenograft tumors, obtained only in animals with estradiol (E₂) pellet implants, doubled control value after 13 weeks of leptin exposure. In three-dimensional cultures, leptin and/or E₂ enhanced cell-cell adhesion. This increased aggregation seems to be dependent on E-cadherin because it was completely abrogated in the presence of function-blocking E-cadherin antibody or EGTA, a calcium-chelating agent. In three-dimensional cultures, leptin and/or E₂ treatment significantly increased cell growth, which was abrogated when E-cadherin function was blocked. These findings well correlated with an increase of mRNA and protein content of E-cadherin in three-dimensional cultures and in xenografts. In MCF-7 cells both hormones were able to activate E-cadherin promoter. Mutagenesis studies, electrophoretic mobility shift assay, and chromatin immunoprecipitation assays revealed that cyclic AMP–responsive element binding protein and Sp1 motifs, present on E-cadherin promoter, were important for the up-regulatory effects induced by both hormones on E-cadherin expression in breast cancer MCF-7 cells. In conclusion, the present study shows how leptin is able to promote tumor cell proliferation and homotypic tumor cell adhesion via an increase of E-cadherin expression. This combined effect may give reasonable emphasis to the important role of this cytokine in stimulating primary breast tumor cell growth and progression, particularly in obese women. [Cancer Res 2007;67(7):3412–21]