Search

Abstract Background The existence of a cross-talk between peritumoral adipocytes and cancer cells has been increasingly investigated. Several studies have shown that these adipocytes protect tumor cells from the effect of anticancer agents. Methods To investigate a potential protective effect of adipocyte-conditioned medium on HER2 positive breast cancer cells exposed to tyrosine kinase inhibitors (TKI) such as lapatinib, we analyzed the sensitivity of HER2 positive breast cancer models in vitro and in vivo on SCID mice in the presence or absence of adipocytes or adipocyte-conditioned medium. Results Conditioned medium from differentiated adipocytes reduced the in vitro sensitivity of the HER2+ cell lines BT474 and SKBR3 to TKI. Particularly, conditioned medium abrogated P27 induction in tumor cells by lapatinib but this was observed only when conditioned medium was present during exposure to lapatinib. In addition, resistance was induced with adipocytes derived from murine NIH3T3 or human hMAD cells but not with fibroblasts or preadipocytes. In vivo studies demonstrated that the contact of the tumors with adipose tissue reduced sensitivity to lapatinib. Soluble factors involved in this resistance were found to be thermolabile. Pharmacological modulation of lipolysis in adipocytes during preparation of conditioned media showed that various lipolysis inhibitors abolished the protective effect of conditioned media on tumor cells, suggesting a role for adipocyte lipolysis in the induction of resistance of tumor cells to TKI. Conclusions Overall, our results suggest that contact of tumor cells with proximal adipose tissue induces resistance to anti HER2 small molecule inhibitors through the production of soluble thermolabile factors, and that this effect can be abrogated using lipolysis inhibitors.

DNA repair mechanisms constitute major defences against agents that cause cancer, degenerative disease and aging. Different repair systems cooperate to maintain the integrity of genetic information. Investigations of DNA repair involvement in human pathology require an efficient tool that takes into account the variety and complexity of repair systems. We have developed a highly sensitive damaged plasmid microarray to quantify cell lysate excision/synthesis (ES) capacities using small amounts of proteins. This microsystem is based on efficient immobilization and conservation on hydrogel coated glass slides of plasmid DNA damaged with a panel of genotoxic agents. Fluorescent signals are generated from incorporation of labelled dNTPs by DNA excision-repair synthesis mechanisms at plasmid sites. Highly precise DNA repair phenotypes i.e. simultaneous quantitative measures of ES capacities toward seven lesions repaired by distinct repair pathways, are obtained. Applied to the characterization of xeroderma pigmentosum (XP) cells at basal level and in response to a low dose of UVB irradiation, the assay showed the multifunctional role of different XP proteins in cell protection against all types of damage. On the other hand, measurement of the ES of peripheral blood mononuclear cells from six donors revealed significant diversity between individuals. Our results illustrate the power of such a parallelized approach with high potential for several applications including the discovery of new cancer biomarkers and the screening of chemical agents modulating DNA repair systems. [ABSTRACT FROM AUTHOR]

Single-agent gemcitabine has shown encouraging results in patients with mantle cell lymphoma (MCL). This phase II study further explored the potential of a gemcitabine-based regimen in patients with relapsed or refractory MCL. Patients <70 years old received the PDG regimen: gemcitabine (1000 mg/m2, days 1 and 8), dexamethasone (40 mg/m2, days 1–4), and cisplatin (100 mg/m2, day 1). Patients ≥70 years of age received dexamethasone and gemcitabine only (DG regimen). Thirty patients (12 in the DG group, 18 in the PDG group) with a median age 66.5 years (range, 47–81) received a median of six cycles in both groups. The overall response rate was 36.4% [95% confidence interval (CI), 15.2% to 64.6%] with the DG regimen and 44.4% (95% CI 24.6% to 66.3%) with the PDG regimen. The median progression-free survival was 3 months (95% CI 0.0–7.9) in the DG group and 8.5 months (95% CI 4.8–12.2) in the PDG group. With a median follow-up of 38.8 months, 13 patients (including 11 given PDG) are still alive. DG was well tolerated, and thrombocytopenia was the most prevalent toxicity in patients receiving PDG. Both regimens deserve to be further investigated as a backbone for combination chemotherapy in patients with MCL. [ABSTRACT FROM AUTHOR]