Uncoupling fork speed and origin activity to identify the primary cause of replicative stress phenotypes

In growing cells, DNA replication precedes mitotic cell division to transmit genetic information to the next generation. The slowing or stalling of DNA replication forks at natural or exogenous obstacles causes "replicative stress" that promotes genomic instability and affects cellular fitness. Replicative stress phenotypes can be characterized at the single-molecule level with DNA combing or stretched DNA fibers, but interpreting the results obtained with these approaches is complicated by the fact that the speed of replication forks is connected to the frequency of origin activation. Primary alterations in fork speed trigger secondary responses in origins, and, conversely, primary alterations in the number of active origins induce compensatory changes in fork speed. Here, by employing interventions that temporally restrict either fork speed or origin firing while still allowing interrogation of the other variable, we report a set of experimental conditions to separate cause and effect in any manipulation that affects DNA replication dynamics. Using HeLa cells and chemical inhibition of origin activity (through a CDC7 kinase inhibitor) and of DNA synthesis (via the DNA polymerase inhibitor aphidicolin), we found that primary effects of replicative stress on velocity of replisomes (fork rate) can be readily distinguished from primary effects on origin firing. Identifying the primary cause of replicative stress in each case as demonstrated here may facilitate the design of methods to counteract replication stress in primary cells or to enhance it in cancer cells to increase their susceptibility to therapies that target DNA repair.The DNA Replication Group is part of the BFU2016-81796-REDC network of excellence. We thank all members of the group for discussions and Dr. Oscar Fernández-Capetillo and Dr. Ana Losada for useful comments on the manuscriptS

Monitoring vascular normalization induced by antiangiogenic treatment with (18)F-fluoromisonidazole-PET

This work was supported by the following sources: Fondo de Investigacion Sanitaria (Ministry of Health, Spain; numbers FIS PI10/0288, FIS PI13/00430, FIS PI 11/00616, CPII14/00005 and FIS PI14/00860; the first two awarded to MQF and the last three to MD), and "Fondo Europeo de Desarrollo Regional (FEDER) - Una manera de hacer Europa". MQF is a recipient of a 2010 Beca-Retorno from the AECC Scientific Foundation. Rosae Foundation and AVON Espana S.A.U. contributed to this work with unrestricted donations. Dovitinib was kindly provided by Novartis.BACKGROUND: Rationalization of antiangiogenics requires biomarkers. Vascular re-normalization is one widely accepted mechanism of action for this drug class. The interstitium of tumors with abnormal vasculature is hypoxic. We sought to track vascular normalization with (18)F-misonidazole ([18F]-FMISO, a probe that detects hypoxia) PET, in response to window-of-opportunity (WoO) treatment with the antiangiogenic dovitinib. METHODS: Two patient-derived pancreas xenografts (PDXs; Panc215 and Panc286) and the spontaneous breast cancer model MMTV-PyMT were used. Animals were treated during 1 week of WoO treatment with vehicle or dovitinib, preceded and followed by [18F]-FMISO-PET, [18F]-FDG-PET, and histologic assessment (dextran extravasation, hypoxia and microvessel staining, and necrosis, cleaved caspase-3 and Ki67 measurements). After WoO treatment, gemcitabine (pancreas)/adriamycin (breast) or vehicle was added and animals were treated until the humane endpoint. Tumor growth inhibition (TGI) and survival were the parameters studied. RESULTS: [18F]-FMISO SUV did not change after dovitinib-WoO treatment compared to vehicle-WoO (0.54 vs. 0.6) treatment in Panc215, but it decreased significantly in Panc286 (0.58 vs. 1.18; P < 0.05). In parallel, 10-KDa perivascular dextran extravasation was not reduced with dovitinib or vehicle-WoO treatment in Panc215, but it was reduced in Panc286. Whereas the addition of dovitinib to gemcitabine was indifferent in Panc215, it increased TGI in Panc286 (TGI switched from -59% to +49%). [18F]-FMISO SUV changes were accompanied by an almost 100% increase in interstitial gemcitabine delivery (665-1260 ng/mL). The results were validated in the PyMT model. CONCLUSIONS: [18F]-FMISO accurately monitored vascular re-normalization and improved interstitial chemotherapy delivery.This work was supported by the following sources: Fondo de Investigacion Sanitaria (Ministry of Health, Spain; numbers FIS PI10/0288, FIS PI13/00430, FIS PI 11/00616, CPII14/00005 and FIS PI14/00860; the first two awarded to MQF and the last three to MD), and "Fondo Europeo de Desarrollo Regional (FEDER) - Una manera de hacer Europa". MQF is a recipient of a 2010 Beca-Retorno from the AECC Scientific Foundation. Rosae Foundation and AVON Espana S.A.U. contributed to this work with unrestricted donations. Dovitinib was kindly provided by Novartis.S

Tumor P70S6K hyperactivation is inversely associated with tumor-infiltrating lymphocytes in triple-negative breast cancer

Purpose: Triple-negative breast cancer (TNBC) is characterized by large heterogeneity and relative lack of available targeted therapies. To find therapeutic strategies for distinct patients with TNBC, several approaches have been used for TNBC clustering, including recently immune and phosphoproteomic patterns. Based on 70-kDa ribosomal protein S6 kinase (P70S6K)-TNBC clustering, the current study explores the immune profiling in TNBC tumors. Methods: Stromal tumor-infiltrating lymphocytes (sTILs) were evaluated in human TNBC tumor samples. Furthermore, immunohistochemistry staining for CD8, CD4, Foxp3, and CD20 was performed in tissue microarrays (TMA) sections. Results: Histological analysis showed decreased sTILs, CD20+ cells, and CD8+/CD4+ ratio in high phosphorylated P70S6K (p-P70S6K) tumors. Moreover, p-P70S6K score was directly correlated with CD4+ and Foxp3+ T cells, while it was inversely correlated with CD8+/CD4+ and CD8+/Foxp3+ ratios. Conclusion: sTIL infiltration and lymphocyte profiling vary in the context of hyperactivation of P70S6K in TNBC tumorsThe project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No 893597. RC is a recipient of the ISCIII grants: PI17/01865 and PI20/01458. MQF is a recipient of the following Grants: AES-PI19/00454 funded by the ISCIII and co-funded by the European Regional Development Fund (ERDF) and B2017/BMD3733 (Immunothercan-CM)—Call for Coordinated Research Groups from Madrid Region—Madrid Regional Government—ERDF funds. The study was also funded by CRIS Contra el Cancer Foundatio

Critically short telomeres and toxicity of chemotherapy in early breast cancer

Cumulative toxicity from weekly paclitaxel (myalgia, peripheral neuropathy, fatigue) compromises long-term administration. Preclinical data suggest that the burden of critically short telomeres ( 21.9% CSTs) had 2-fold higher number of neuropathy (P = 0.04) or fatigue (P = 0.019) episodes and >3-fold higher number of myalgia episodes (P = 0.005). The average telomere length was unrelated to the incidence of side effects.The percentage of CSTs, but not the average telomere size, is associated with weekly paclitaxel-derived toxicity.This work was supported by the Fondo de Investigación Sanitaria [FIS PI10/00288 and FIS PI13/00430]; AECC Scientific Foundation [Beca de Retorno-2010, to MQF]; Spanish Ministry of Economy and Competitiveness Projects [SAF2013-45111-R]; Madrid Regional Government Projects [S2010/BMD- 2303]; AXA Research Found; Fundación Botin; AVON Spain; and Boehringer-Ingelheim Spain.S

RANK is an independent biomarker of poor prognosis in estrogen receptor-negative breast cancer and a therapeutic target in patient-derived xenografts

Despite strong preclinical data, the therapeutic benefit of the RANKL inhibitor denosumab in BC patients, beyond its bone-related effects, is unclear. Here, we investigated the prognostic value of RANK expression and its functionality in human BC. We analyzed RANK and RANKL expression in more than 1500 BC cases (777 being estrogen receptor-negative (ER-)) from four independent cohorts. We confirmed that RANK is more frequently expressed in ER- tumors, but it is also found in a subset of ER+ tumors. In ER- BC, RANK expression was independently associated with poor outcome, especially in postmenopausal patients and those who received adjuvant chemotherapy. Gene expression analyses unraveled distinct biology associated with RANK in relation to ER expression and menopause, and evidenced enhanced RANK activation in ER- postmenopausal tumors, together with regulation of metabolic pathways. Functional studies and transcriptomic analyses in ER- RANK+ patients-derived orthoxenografts demonstrated that activation of RANK signaling pathway promotes tumor cell proliferation and stemness, and regulates multiple biological processes including tumor immune surveillance and metabolism. Our results demonstrate that RANK expression is an independent poor prognosis biomarker in postmenopausal ER- BC patients and support the rational of using RANK pathway inhibitors in combination with chemotherapy in ER- BC.N

RANK is a poor prognosis marker and a therapeutic target in ER-negative postmenopausal breast cancer

Despite strong preclinical data, the therapeutic benefit of the RANKL inhibitor, denosumab, in breast cancer patients, beyond the bone, is unclear. Aiming to select patients who may benefit from denosumab, we hereby analyzed RANK and RANKL protein expression in more than 2000 breast tumors (777 estrogen receptor-negative, ER-) from four independent cohorts. RANK protein expression was more frequent in ER- tumors, where it associated with poor outcome and poor response to chemotherapy. In ER- breast cancer patient-derived orthoxenografts (PDXs), RANKL inhibition reduced tumor cell proliferation and stemness, regulated tumor immunity and metabolism, and improved response to chemotherapy.Intriguingly, tumor RANK protein expression associated with poor prognosis in postmenopausal breast cancer patients, activation of NFKB signaling and modulation of immune and metabolic pathways, suggesting that RANK signaling increases after menopause. Our results demonstrate that RANK expression is an independent biomarker of poor prognosis in postmenopausal ER- breast cancer patients and support the therapeutic benefit of RANK pathway inhibitors, such as denosumab, in breast cancer patients with RANK+ ER- tumors after menopause