Characterization of the role of TMEM45A in cancer cell sensitivity to cisplatin.

TMEM45A is a transmembrane protein involved in tumor progression and cancer resistance to chemotherapeutic agents in hypoxic condition. It is correlated to a low breast cancer patient overall survival. However, little is known about this protein, in particular the mechanisms by which TMEM45A modulates cancer cell chemosensitivity. In this work, the messenger RNA expression of TMEM45A was assessed in head and neck squamous cell carcinoma (HNSCC) and renal cell carcinoma (RCC) biopsies. TMEM45A was upregulated in patients diagnosed for head and neck or renal cancer. Then, the implication of this protein in cisplatin sensitivity was explored in SQD9 and RCC4 + pVHL cells. TMEM45A inactivation decreased cell proliferation and modulated cell responses to cisplatin. Indeed, TMEM45A inactivation increased the sensitivity of SQD9 cells to cisplatin, whereas it rendered RCC4 + pVHL cells resistant to this anticancer agent. Through RNA-sequencing analysis, we identified several deregulated pathways that indicated that the impact on cisplatin sensitivity may be associated to the inhibition of DNA damage repair and to UPR pathway activation. This study demonstrated, for the first time, an anti or a pro-apoptotic role of this protein depending on the cancer type and highlighted the role of TMEM45A in modulating patient responses to treatment.

Cycling hypoxia induces a specific amplified inflammatory phenotype in endothelial cells and enhances tumor-promoting inflammation in vivo.

Abnormal architecture of the tumor blood network, as well as heterogeneous erythrocyte flow, leads to temporal fluctuations in tissue oxygen tension exposing tumor and stromal cells to cycling hypoxia. Inflammation is another feature of tumor microenvironment and is considered as a new enabling characteristic of tumor progression. As cycling hypoxia is known to participate in tumor aggressiveness, the purpose of this study was to evaluate its role in tumor-promoting inflammation. Firstly, we assessed the impact of cycling hypoxia in vitro on endothelial inflammatory response induced by tumor necrosis factor α. Results showed that endothelial cells exposed to cycling hypoxia displayed an amplified proinflammatory phenotype, characterized by an increased expression of inflammatory cytokines, namely, interleukin (IL)-6 and IL-8; by an increased expression of adhesion molecules, in particular intercellular adhesion molecule-1 (ICAM-1); and consequently by an increase in THP-1 monocyte adhesion. This exacerbation of endothelial inflammatory phenotype occurs through nuclear factor-κB overactivation. Secondly, the role of cycling hypoxia was studied on overall tumor inflammation in vivo in tumor-bearing mice. Results showed that cycling hypoxia led to an enhanced inflammation in tumors as prostaglandin-endoperoxide synthase 2 (PTGS2), IL-6, CXCL1 (C-X-C motif ligand 1), and macrophage inflammatory protein 2 (murine IL-8 functional homologs) mRNA expression was increased and as a higher leukocyte infiltration was evidenced. Furthermore, cycling hypoxia-specific inflammatory phenotype, characterized by a simultaneous (baculoviral inhibitor of apoptosis repeat-containing 5)(low)/PTGS2(high)/ICAM-1(high)/IL-6(high)/IL-8(high) expression, is associated with a poor prognosis in human colon cancer. This new phenotype could thus be used in clinic to more precisely define prognosis for colon cancer patients. In conclusion, our findings evidenced for the first time the involvement of cycling hypoxia in tumor-promoting inflammation amplification.

An efficient one-pot approach to bridged bicyclic ring-systems through consecutive hetero-domino transformations: a mechanistic rationale and further rearrangements.

This article describes the design of olefin-generated/reagent-modulated consecutive hetero-domino reactions of 1,2-unsaturated bicyclic diols, which are potentially of great use, initiated by PhI(OAc)(2), continued by [Pb(OAc)(4)], and completed by use of a mild base (K(2)CO(3)). Inversion of a quaternary center has been achieved through a three-reaction sequence: a domino transformation followed by an m-CPBA-mediated Baeyer-Villiger oxidation and subsequent reductive lactone ring opening.