Acidic pH is an important feature of tumor microenvironment and a major determinant of tumor progression. We reported that cancer cells upregulate autophagy as a survival mechanism to acidic stress. Inhibition of autophagy by administration of chloroquine (CQ) in combination anticancer therapies is currently evaluated in clinical trials. We observed in 3 different human cancer cell lines cultured at acidic pH that autophagic flux is not blocked by CQ. This was consistent with a complete resistance to CQ toxicity in cells cultured in acidic conditions. Conversely, the autophagy-inhibiting activity of Lys-01, a novel CQ derivative, was still detectable at low pH. The lack of CQ activity was likely dependent on a dramatically reduced cellular uptake at acidic pH. Using cell lines stably adapted to chronic acidosis we could confirm that CQ lack of activity was merely caused by acidic pH. Moreover, unlike CQ, Lys-01 was able to kill low pH-adapted cell lines, although higher concentrations were required as compared with cells cultured at normal pH conditions. Notably, buffering medium pH in low pH-adapted cell lines reverted CQ resistance. In vivo analysis of tumors treated with CQ showed that accumulation of strong LC3 signals was observed only in normoxic areas but not in hypoxic/acidic regions. Our observations suggest that targeting autophagy in the tumor environment by CQ may be limited to well-perfused regions but not achieved in acidic regions, predicting possible limitations in efficacy of CQ in antitumor therapies.

Immunotherapy efficacy relies on the crosstalk within the tumor microenvironment between cancer and dendritic cells (DCs) resulting in the induction of a potent and effective antitumor response. DCs have the specific role of recognizing cancer cells, taking up tumor antigens (Ags) and then migrating to lymph nodes for Ag (cross)-presentation to naïve T cells. Interferon-α-conditioned DCs (IFN-DCs) exhibit marked phagocytic activity and the special ability of inducing Ag-specific T-cell response. Here, we have developed a novel microfluidic platform recreating tightly interconnected cancer and immune systems with specific 3D environmental properties, for tracking human DC behaviour toward tumor cells. By combining our microfluidic platform with advanced microscopy and a revised cell tracking analysis algorithm, it was possible to evaluate the guided efficient motion of IFN-DCs toward drug-treated cancer cells and the succeeding phagocytosis events. Overall, this platform allowed the dissection of IFN-DC-cancer cell interactions within 3D tumor spaces, with the discovery of major underlying factors such as CXCR4 involvement and underscored its potential as an innovative tool to assess the efficacy of immunotherapeutic approaches.

Background: Inefficient T-cell access to the tumor microenvironment (TME) is among the causes of tumor immune-resistance. Previous evidence demonstrated that targeting CXCR4 improves anti-PD-1/PD-L1 efficacy reshaping TME. To evaluate the role of newly developed CXCR4 antagonists (PCT/IB2011/000120/ EP2528936B1/ US2013/0079292A1) in potentiating anti-PD-1 efficacy two syngeneic murine models, the MC38 colon cancer and the B16 melanoma-human CXCR4-transduced, were employed. Methods: Mice were subcutaneously injected with MC38 (1 × 10 6) or B16-hCXCR4 (5 × 10 5). After two weeks, tumors bearing mice were intraperitoneally (ip) treated with murine anti-PD-1 [RMP1-14] (5 mg/kg, twice week for 2 weeks), Pep R (2 mg/kg, 5 days per week for 2 weeks), or both agents. The TME was evaluated through immunohistochemistry and flow-cytometry. In addition, the effects of the human-anti-PD-1 nivolumab and/or Peptide-R54 (Pep R54), were evaluated on human melanoma PES43 cells and xenografts treated.

With the intent to identify biomarkers in renal cell carcinoma (RCC) the functional status of T-regulatory cells (Tregs) was investigated in primary RCC. Tregs were isolated from tumoral-(TT), peritumoral tissue-(PT) and peripheral blood-(PB) of 42 primary RCC patients and function evaluated through effector T cells (Teff) proliferation, cytokines release and demethylation of Treg Specific Region (TSDR). The highest value of Tregs was detected in TT with the uppermost amount of effector-Tregs-(CD4+CD25hiFOXP3hiCD45RA-). PB-RCC Tregs efficiently suppress Teff proliferation compared to healthy donor (HD)-Tregs and, at the intrapatient evaluation, TT-derived Tregs were the most suppressive. Higher demethylation TSDR was detected in TT- and PB-RCC Tregs vs HD-Tregs (P <0,001). CXCR4 is highly expressed on Tregs, thus we wished to modulate Tregs function through CXCR4 inhibition. CXCR4 antagonism, elicited by a new peptidic antagonist, Peptide-R29, efficiently reversed Tregs suppression of Teff proliferation. Thus Tregs functional evaluation precisely reflects Tregs status and may be a reliable biomarker of tumoral immune response. In addition, treatment with CXCR4 antagonist, impairing Tregs function, could improve the anticancer immune response, in combination with conventional therapy and/or immunotherapy such as checkpoints inhibitors.

The tumor microenvironment (TME) is a complex entity where host immune and non-immune cells establish a dynamic crosstalk with cancer cells. Through cell-cell interactions, which are mediated by key signals, such as the PD-1/PD-L1 axis, as well as the release of soluble mediators, this articulated process defines the nature of TME determining tumor development, prognosis, and response to therapy. Specifically, tumors are characterized by cellular plasticity that allows for the microenvironment to polarize towards inflammation or immunosuppression. Thus, the dynamic crosstalk among cancer, stromal, and immune components crucially favors the dominance of one of the Janus-faced contexture of TME crucial to the outcome of tumor development and therapeutic response. However, mostly, TME is dominated by an immunosuppressive landscape that blocks antitumor immunity and sustain tumor progression. Hence, in most cases, the immunosuppressive components of TME are highly competent in suppressing tumor-specific CD8+ T lymphocytes, the effectors of cancer destruction. In this complex context, immunotherapy aims to arm the hidden Janus face of TME disclosing and potentiating antitumor immune signals. Herein, we discuss recent knowledge on the immunosuppressive crosstalk within TME, and share perspectives on how immunotherapeutic approaches may exploit tumor immune signals to generate antitumor immunity.

Sustained autophagy contributes to the metabolic adaptation of cancer cells to hypoxic and acidic microenvironments. Since cells in such environments are resistant to conventional cytotoxic drugs, inhibition of autophagy represents a promising therapeutic strategy in clinical oncology. We previously reported that the efficacy of hydroxychloroquine (HCQ), an autophagy inhibitor under clinical investigation is strongly impaired in acidic tumor environments, due to poor uptake of the drug, a phenomenon widely associated with drug resistance towards many weak bases. In this study we identified salinomycin (SAL) as a potent inhibitor of autophagy and cytotoxic agent effective on several cancer cell lines under conditions of transient and chronic acidosis. Since SAL has been reported to specifically target cancer-stem cells (CSC), we used an established model of breast CSC and CSC derived from breast cancer patients to examine whether this specificity may be associated with autophagy inhibition. We indeed found that CSC-like cells are more sensitive to autophagy inhibition compared to cells not expressing CSC markers. We also report that the ability of SAL to inhibit mammosphere formation from CSC-like cells was dramatically enhanced in acidic conditions. We propose that the development and use of clinically suitable SAL derivatives may result in improved autophagy inhibition in cancer cells and CSC in the acidic tumor microenvironment and lead to clinical benefits.

BACKGROUND AND PURPOSEPropranolol is a vasoactive drug that shows antiangiogenic and antitumour activities in melanoma. However, it is unknown whether these activities are dose-dependent and whether there is a relationship between systemic vascular effects of propranolol and anti-melanoma activity. EXPERIMENTAL APPROACHEffects of increasing doses of propranolol (10, 20, 30 and 40 mg·kg À1 ·day À1 ) on tumour growth were studied in B16F10 melanoma-bearing mice. Histological and biochemical analyses were used to assess propranolol effects on angiogenesis and cancer cell proliferation. Systemic vascular resistance (SVR) was evaluated by measuring cardiac output and arterial BP. KEY RESULTSIn vitro analyses revealed that B16F10 cells expressed β-adrenoceptors, but neither isoprenaline, a β-adrenoceptor agonist, nor the β-blocker propranolol affected cancer cell proliferation. In vivo studies showed that the antitumour efficacy of propranolol follows a U-shaped biphasic dose-response curve. Low doses (10 and 20 mg·kg À1 ·day À1 ) significantly inhibit tumour growth, whereas higher doses are progressively less effective. We also found that high-dose propranolol stimulates tumour arteriogenesis whereas no effect on angiogenesis was observed at any dose. Based on these data and considering that propranolol is a vasoactive drug, we hypothesized that it causes systemic vasoconstriction or vasodilation depending on the dose and thus alters tumour perfusion and growth. Consistent with this hypothesis, we found that propranolol has a biphasic effect on SVR with low and high doses producing vasoconstriction and vasodilation respectively. CONCLUSIONS AND IMPLICATIONSPropranolol inhibits melanoma growth in a U-shaped biphasic manner. A direct relationship exists between SVR and antimelanoma activity.Abbreviations α-SMA, α-smooth muscle actin; CO, cardiac output; GAPDH, Glyceraldehyde-3-phosphate dehydrogenase; HR, heart rate; IB4, isolectin B4; SV, stroke volume; SVR, systemic vascular resistance; vWF, Von Willebrand Factor Introduction β-Adrenoceptors are a family of G-protein coupled receptors comprising three subtypes, β 1 , β 2 and β 3 , which act by activating a Gs protein. These receptors play a role in the regulation of peripheral vascular resistance, heart function and airway reactivity, as well as a variety of metabolic and CNS functions. β-Adrenoceptors also regulate cellular processes involved in cancer and angiogenesis and are the molecular target of β-blockers, a class of drugs which inhibits the interaction of catecholamines with β-adrenoceptors.In vitro studies indicate that propranolol, the prototype of β-blockers, reduces melanoma cell proliferation in human and murine melanoma cell lines (Dal Monte et al., 2013;Moretti et al., 2013;Calvani et al., 2015;Wrobel and Le Gal, 2015). Furthermore, the systemic administration of propranolol slows down tumour development in immunodeficient mice transplanted with human melanoma cells (Wrobel and Le Gal, 2015) and inhibits the effects of stress on the growth and metast...

Cardiac dysfunction is often observed in patients with cancer also representing a serious problem limiting chemotherapeutic intervention and even patient survival. In view of the recently established role of the immune system in the control of cancer growth, the present work has been undertaken to investigate the effects of a panel of the most important inflammatory cytokines on the integrity and function of mitochondria, as well as of the cytoskeleton, two key elements in the functioning of cardiomyocytes. Either mitochondria features or actomyosin cytoskeleton organization of in vitro‐cultured cardiomyocytes treated with different inflammatory cytokines were analyzed. In addition, to investigate the interplay between tumor growth and cardiac function in an in vivo system, immunocompetent female mice were inoculated with cancer cells and treated with the chemotherapeutic drug doxorubicin at a dosing schedule able to suppress tumor growth without inducing cardiac alterations. Analyses carried out in cardiomyocytes treated with the inflammatory cytokines, such as tumor necrosis factor α (TNF‐α), interferon γ (IFN‐γ), interleukin 6 (IL‐6), IL‐8, and IL‐1β revealed severe phenotypic changes, for example, of contractile cytoskeletal elements, mitochondrial membrane potential, mitochondrial reactive oxygen species production and mitochondria network organization. Accordingly, in immunocompetent mice, the tumor growth was accompanied by increased levels of the inflammatory cytokines TNF‐α, IFN‐γ, IL‐6, and IL‐8, either in serum or in the heart tissue, together with a significant reduction of ventricular systolic function. The alterations of mitochondria and of microfilament system of cardiomyocytes, due to the systemic inflammation associated with cancer growth, could be responsible for remote cardiac injury and impairment of systolic function observed in vivo.