Increasing membrane polyunsaturated fatty acids sensitizes non-small cell lung cancer to anti-PD-1/PD-L1 immunotherapy.

Immune checkpoints inhibitors (ICIs) as anti-PD-1/anti-PD-L1 have been approved as first-line treatment in patients with non-small cell lung cancer (NSCLC), but only 25 % of patients achieve durable response. We previously unveiled that estrogen receptor α transcriptionally up-regulates PD-L1 and aromatase inhibitors such as letrozole increase the efficacy of pembrolizumab. Here we investigated if letrozole may have additional immune-sensitizing mechanisms. We found that higher the level of PD-L1 in NSCLC, higher the activation of SREBP1c that transcriptionally increases fatty acid synthase and stearoyl-CoA desaturase enzymes, increasing the amount of polyunsaturated fatty acids (PUFAs). Letrozole further up-regulated SREBP1c-mediated transcription of lipogenic genes, and increased the amount of PUFAs, thereby leading to greater membrane fluidity and reduced binding between PD-L1 and PD-1. The same effects were observed upon supplementation with ω3-PUFA docosahexaenoic acid (DHA) that enhanced the efficacy of pembrolizumab in humanized NSCLC immune-xenografts. We suggest that PUFA enrichment in membrane phospholipids improves the efficacy of ICIs. We propose to repurpose letrozole or DHA as new immune-sensitizing agents in NSCLC.

TFEB controls sensitivity to chemotherapy and immuno-killing in non-small cell lung cancer.

BACKGROUND: In non-small cell lung cancer (NSCLC) the efficacy of chemo-immunotherapy is affected by the high expression of drug efflux transporters as ABCC1 and by the low expression of ABCA1, mediating the isopentenyl pyrophosphate (IPP)-dependent anti-tumor activation of Vγ9Vδ2 T-lymphocytes. In endothelial cells ABCA1 is a predicted target of the transcription factor EB (TFEB), but no data exists on the correlation between TFEB and ABC transporters involved in the chemo-immuno-resistance in NSCLC. METHODS: The impact of TFEB/ABCC1/ABCA1 expression on NSCLC patients' survival was analyzed in the TCGA-LUAD cohort and in a retrospective cohort of our institution. Human NSCLC cells silenced for TFEB (shTFEB) were analyzed for ABC transporter expression, chemosensitivity and immuno-killing. The chemo-immuno-sensitizing effects of nanoparticles encapsulating zoledronic acid (NZ) on shTFEB tumors and on tumor immune-microenvironment were evaluated in Hu-CD34+ mice by single-cell RNA-sequencing. RESULTS: TFEBlowABCA1lowABCC1high and TFEBhighABCA1highABCC1low NSCLC patients had the worst and the best prognosis, respectively, in the TCGA-LUAD cohort and in a retrospective cohort of patients receiving platinum-based chemotherapy or immunotherapy as first-line treatment. By silencing shTFEB in NSCLC cells, we demonstrated that TFEB was a transcriptional inducer of ABCA1 and a repressor of ABCC1. shTFEB cells had also a decreased activity of ERK1/2/SREBP2 axis, implying reduced synthesis and efflux via ABCA1 of cholesterol and its intermediate IPP. Moreover, TFEB silencing reduced cholesterol incorporation in mitochondria: this event increased the efficiency of OXPHOS and the fueling of ABCC1 by mitochondrial ATP. Accordingly, shTFEB cells were less immuno-killed by the Vγ9Vδ2 T-lymphocytes activated by IPP and more resistant to cisplatin. NZ, which increased IPP efflux but not OXPHOS and ATP production, sensitized shTFEB immuno-xenografts, by reducing intratumor proliferation and increasing apoptosis in response to cisplatin, and by increasing the variety of anti-tumor infiltrating cells (Vγ9Vδ2 T-lymphocytes, CD8+T-lymphocytes, NK cells). CONCLUSIONS: This work suggests that TFEB is a gatekeeper of the sensitivity to chemotherapy and immuno-killing in NSCLC, and that the TFEBlowABCA1lowABCC1high phenotype can be predictive of poor response to chemotherapy and immunotherapy. By reshaping both cancer metabolism and tumor immune-microenvironment, zoledronic acid can re-sensitize TFEBlow NSCLCs, highly resistant to chemo- and immunotherapy.

Autocrine 17-ß-Estradiol/Estrogen Receptor-α Loop Determines the Response to Immune Checkpoint Inhibitors in Non-Small Cell Lung Cancer.

PURPOSE: The response to immune checkpoint inhibitors (ICI) often differs between genders in non-small cell lung cancer (NSCLC), but metanalyses results are controversial, and no clear mechanisms are defined. We aim at clarifying the molecular circuitries explaining the differential gender-related response to anti-PD-1/anti-PD-L1 agents in NSCLC. EXPERIMENTAL DESIGN: We prospectively analyzed a cohort of patients with NSCLC treated with ICI as a first-line approach, and we identified the molecular mechanisms determining the differential efficacy of ICI in 29 NSCLC cell lines of both genders, recapitulating patients' phenotype. We validated new immunotherapy strategies in mice bearing NSCLC patient-derived xenografts and human reconstituted immune system ("immune-PDXs"). RESULTS: In patients, we found that estrogen receptor α (ERα) was a predictive factor of response to pembrolizumab, stronger than gender and PD-L1 levels, and was directly correlated with PD-L1 expression, particularly in female patients. ERα transcriptionally upregulated CD274/PD-L1 gene, more in females than in males. This axis was activated by 17-ß-estradiol, autocrinely produced by intratumor aromatase, and by the EGFR-downstream effectors Akt and ERK1/2 that activated ERα. The efficacy of pembrolizumab in immune-PDXs was significantly improved by the aromatase inhibitor letrozole, which reduced PD-L1 and increased the percentage of antitumor CD8+T-lymphocytes, NK cells, and Vγ9Vδ2 T-lymphocytes, producing durable control and even tumor regression after continuous administration, with maximal benefit in 17-ß-estradiol/ERα highfemale immune-xenografts. CONCLUSIONS: Our work unveils that 17-ß-estradiol/ERα status predicts the response to pembrolizumab in patients with NSCLC. Second, we propose aromatase inhibitors as new gender-tailored immune-adjuvants in NSCLC. See related commentary by Valencia et al., p. 3832.

Mitochondrial ROS drive resistance to chemotherapy and immune-killing in hypoxic non-small cell lung cancer.

BACKGROUND: Solid tumors subjected to intermittent hypoxia are characterized by resistance to chemotherapy and immune-killing by effector T-lymphocytes, particularly tumor-infiltrating Vγ9Vδ2 T-lymphocytes. The molecular circuitries determining this double resistance are not known. METHODS: We analyzed a panel of 28 human non-small cell lung cancer (NSCLC) lines, using an in vitro system simulating continuous and intermittent hypoxia. Chemosensitivity to cisplatin and docetaxel was evaluated by chemiluminescence, ex vivo Vγ9Vδ2 T-lymphocyte expansion and immune-killing by flow cytometry. Targeted transcriptomics identified efflux transporters and nuclear factors involved in this chemo-immuno-resistance. The molecular mechanism linking Hypoxia-inducible factor-1α (HIF-1α), CCAAT/Enhancer Binding Protein-ß (C/EBP-ß) isoforms LAP and LIP, ABCB1, ABCC1 and ABCA1 transporters were evaluated by immunoblotting, RT-PCR, RNA-IP, ChIP. Oxidative phosphorylation, mitochondrial ATP, ROS, depolarization, O2 consumption were monitored by spectrophotometer and electronic sensors. The role of ROS/HIF-1α/LAP axis was validated in knocked-out or overexpressing cells, and in humanized (Hu-CD34+NSG) mice bearing LAP-overexpressing tumors. The clinical meaning of LAP was assessed in 60 NSCLC patients prospectively enrolled, treated with chemotherapy. RESULTS: By up-regulating ABCB1 and ABCC1, and down-regulating ABCA1, intermittent hypoxia induced a stronger chemo-immuno-resistance than continuous hypoxia in NSCLC cells. Intermittent hypoxia impaired the electron transport chain and reduced O2 consumption, increasing mitochondrial ROS that favor the stabilization of C/EBP-ß mRNA mediated by HIF-1α. HIF-1α/C/EBP-ß mRNA binding increases the splicing of C/EBP-ß toward the production of LAP isoform that transcriptionally induces ABCB1 and ABCC1, promoting the efflux of cisplatin and docetaxel. LAP also decreases ABCA1, limiting the efflux of isopentenyl pyrophosphate, i.e. the endogenous activator of Vγ9Vδ2 T-cells, and reducing the immune-killing. In NSCLC patients subjected to cisplatin-based chemotherapy, C/EBP-ß LAP was abundant in hypoxic tumors and was associated with lower response to treatment and survival. LAP-overexpressing tumors in Hu-CD34+NSG mice recapitulated the patients' chemo-immuno-resistant phenotype. Interestingly, the ROS scavenger mitoquinol chemo-immuno-sensitized immuno-xenografts, by disrupting the ROS/HIF-1α/LAP cascade. CONCLUSIONS: The impairment of mitochondrial metabolism induced by intermittent hypoxia increases the ROS-dependent stabilization of HIF-1α/LAP complex in NSCLC, producing chemo-immuno-resistance. Clinically used mitochondrial ROS scavengers may counteract such double resistance. Moreover, we suggest C/EBP-ß LAP as a new predictive and prognostic factor in NSCLC patients.

Olvanil activates sensory nerve fibers, increases T cell response and decreases metastasis of breast carcinoma.

BACKGROUND: Inactivation of sensory neurons expressing transient receptor potential vanilloid 1 (TRPV1) enhances breast cancer metastasis. Sensory neurons have profound effects on immune response to a wide range of diseases including cancer. Hence, activation of sensory nerves using feasible approaches such as specific TRPV1 agonists may inhibit breast cancer metastasis through neuroimmune pathways. TRPV1 agonists are considered for the treatment of pain and inflammatory diseases. METHODS: We here first determined the effects of four different TRPV1 agonists on proliferation of three different metastatic breast carcinoma cells since TRPV1 is also expressed in cancer cells. Based on the results obtained under in-vitro conditions, brain metastatic breast carcinoma cells (4TBM) implanted orthotopically into the mammary-pad of Balb-c mice followed by olvanil treatment (i.p.). Changes in tumor growth, metastasis and immune response to cancer cells were determined. RESULTS: Olvanil dose-dependently activated sensory nerve fibers and markedly suppressed lung and liver metastasis without altering the growth of primary tumors. Olvanil (5 mg/kg) systemically increased T cell count, enhanced intra-tumoral recruitment of CD8+ T cells and increased IFN-γ response to irradiated cancer cells and Con-A. Anti-inflammatory changes such as increased IL-10 and decrease IL-6 as well as S100A8+ cells were observed following olvanil treatment. CONCLUSIONS: Our results show that anti-metastatic effects of olvanil is mainly due to activation of neuro-immune pathways since olvanil dose used here is not high enough to directly activate immune cells. Furthermore, olvanil effectively depletes sensory neuropeptides; hence, olvanil is a good non-pungent alternative to capsaicin.

Effects of in-vitro modulation of TRPV1 activity on immune response of mice bearing metastatic breast carcinoma: Enhanced inflammatory response may hinder therapeutic potentials of TRPV1 agonists.

AIMS: Activation of transient receptor potential vanilloid 1 (TRPV1) ion channels inhibits inflammation, enhance cytotoxic immune response, and may have therapeutic potential in treatment of cancer characterized by increased systemic inflammation. We here determined how activation of TRPV1 alters immune response of tumor-bearing mice. MAIN METHODS: Three different metastatic subset of 4 T1 breast carcinoma cells were used to induce tumors in Balb-c mice. Mix leukocyte cultures (MLCs) using spleens and draining lymph nodes were prepared and stimulated with various challenges. Effects TRPV1 agonists including capsaicin, antagonist (AMG9810) and Gambogic Amide (GA), a TrkA agonist that sensitizes TRPV1, on secreted levels of cytokines were determined. KEY FINDINGS: MLCs of tumor-bearing mice secreted markedly higher levels of IL-6 and lower levels of IFN-γ compared to control mice. We observed differential effects of TRPV1 agonists in control and mice bearing different subset of metastatic cells. TRPV1 increased IFN-γ and IL-17 secretion in control mice while they markedly increased IL-6 secretion and suppressed IFN--γ secretion in tumor-bearing mice. Unexpectedly, AMG9810 acted as an inverse agonist and did not antagonize the effects of TRPV1 agonists. SIGNIFICANCE: Our results demonstrate constitutive activity of TRPV1 in immune cells, suggesting cross activation. To prevent excessive chronic activation of TRPV1 in immune cells in the presence of metastatic breast carcinoma, lower doses of TRPV1 agonist should be considered. Unexpected findings further document that a drug can have multiple intrinsic activities depending on surrounding factors can act on the same receptor as an agonist, antagonist or inverse agonist.

Hypoxia, endoplasmic reticulum stress and chemoresistance: dangerous liaisons.

Solid tumors often grow in a micro-environment characterized by < 2% O2 tension. This condition, together with the aberrant activation of specific oncogenic patwhays, increases the amount and activity of the hypoxia-inducible factor-1α (HIF-1α), a transcription factor that controls up to 200 genes involved in neoangiogenesis, metabolic rewiring, invasion and drug resistance. Hypoxia also induces endoplasmic reticulum (ER) stress, a condition that triggers cell death, if cells are irreversibly damaged, or cell survival, if the stress is mild.Hypoxia and chronic ER stress both induce chemoresistance. In this review we discuss the multiple and interconnected circuitries that link hypoxic environment, chronic ER stress and chemoresistance. We suggest that hypoxia and ER stress train and select the cells more adapted to survive in unfavorable conditions, by activating pleiotropic mechanisms including apoptosis inhibition, metabolic rewiring, anti-oxidant defences, drugs efflux. This adaptative process unequivocally expands clones that acquire resistance to chemotherapy.We believe that pharmacological inhibitors of HIF-1α and modulators of ER stress, although characterized by low specificty and anti-cancer efficacy when used as single agents, may be repurposed as chemosensitizers against hypoxic and chemorefractory tumors in the next future.

Hypoxia Dictates Metabolic Rewiring of Tumors: Implications for Chemoresistance.

Hypoxia is a condition commonly observed in the core of solid tumors. The hypoxia-inducible factors (HIF) act as hypoxia sensors that orchestrate a coordinated response increasing the pro-survival and pro-invasive phenotype of cancer cells, and determine a broad metabolic rewiring. These events favor tumor progression and chemoresistance. The increase in glucose and amino acid uptake, glycolytic flux, and lactate production; the alterations in glutamine metabolism, tricarboxylic acid cycle, and oxidative phosphorylation; the high levels of mitochondrial reactive oxygen species; the modulation of both fatty acid synthesis and oxidation are hallmarks of the metabolic rewiring induced by hypoxia. This review discusses how metabolic-dependent factors (e.g., increased acidification of tumor microenvironment coupled with intracellular alkalinization, and reduced mitochondrial metabolism), and metabolic-independent factors (e.g., increased expression of drug efflux transporters, stemness maintenance, and epithelial-mesenchymal transition) cooperate in determining chemoresistance in hypoxia. Specific metabolic modifiers, however, can reverse the metabolic phenotype of hypoxic tumor areas that are more chemoresistant into the phenotype typical of chemosensitive cells. We propose these metabolic modifiers, able to reverse the hypoxia-induced metabolic rewiring, as potential chemosensitizer agents against hypoxic and refractory tumor cells.

Insights into P-Glycoprotein Inhibitors: New Inducers of Immunogenic Cell Death.

Doxorubicin is a strong inducer of immunogenic cell death (ICD), but it is ineffective in P-glycoprotein (Pgp)-expressing cells. Indeed, Pgp effluxes doxorubicin and impairs the immunesensitizing functions of calreticulin (CRT), an "eat-me" signal mediating ICD. It is unknown if classical Pgp inhibitors, designed to reverse chemoresistance, may restore ICD. We addressed this question by using Pgp-expressing cancer cells, treated with Tariquidar, a clinically approved Pgp inhibitor, and R-3 compound, a N,N-bis(alkanol)amine aryl ester derivative with the same potency of Tariquidar as Pgp inhibitor. In Pgp-expressing/doxorubicin-resistant cells, Tariquidar and R-3 increased doxorubicin accumulation and toxicity, reduced Pgp activity, and increased CRT translocation and ATP and HMGB1 release. Unexpectedly, only R-3 promoted phagocytosis by dendritic cells and activation of antitumor CD8+T-lymphocytes. Although Tariquidar did not alter the amount of Pgp present on cell surface, R-3 promoted Pgp internalization and ubiquitination, disrupting its interaction with CRT. Pgp knock-out restores doxorubicin-induced ICD in MDA-MB-231/DX cells that recapitulated the phenotype of R-3-treated cells. Our work demonstrates that plasma membrane-associated Pgp prevents a complete ICD notwithstanding the release of ATP and HMGB1, and the exposure of CRT. Pharmacological compounds reducing Pgp activity and amount may act as promising chemo- and immunesensitizing agents.

ABCA1/ABCB1 Ratio Determines Chemo- and Immune-Sensitivity in Human Osteosarcoma.

The ATP Binding Cassette transporter B1 (ABCB1) induces chemoresistance in osteosarcoma, because it effluxes doxorubicin, reducing the intracellular accumulation, toxicity, and immunogenic cell death induced by the drug. The ATP Binding Cassette transporter A1 (ABCA1) effluxes isopentenyl pyrophosphate (IPP), a strong activator of anti-tumor Vγ9Vδ2 T-cells. Recruiting this population may represent an alternative strategy to rescue doxorubicin efficacy in ABCB1-expressing osteosarcoma. In this work, we analyzed how ABCA1 and ABCB1 are regulated in osteosarcoma, and if increasing the ABCA1-dependent activation of Vγ9Vδ2 T-cells could be an effective strategy against ABCB1-expressing osteosarcoma. We used 2D-cultured doxorubicin-sensitive human U-2OS and Saos-2 cells, their doxorubicin-resistant sublines (U-2OS/DX580 and Saos-2/DX580), and 3D cultures of U-2OS and Saos-2 cells. DX580-sublines and 3D cultures had higher levels of ABCB1 and higher resistance to doxorubicin than parental cells. Surprisingly, they had reduced ABCA1 levels, IPP efflux, and Vγ9Vδ2 T-cell-induced killing. In these chemo-immune-resistant cells, the Ras/Akt/mTOR axis inhibits the ABCA1-transcription induced by Liver X Receptor α (LXRα); Ras/ERK1/2/HIF-1α axis up-regulates ABCB1. Targeting the farnesylation of Ras with self-assembling nanoparticles encapsulating zoledronic acid (NZ) simultaneously inhibited both axes. In humanized mice, NZ reduced the growth of chemo-immune-resistant osteosarcomas, increased intratumor necro-apoptosis, and ABCA1/ABCB1 ratio and Vγ9Vδ2 T-cell infiltration. We suggest that the ABCB1highABCA1low phenotype is indicative of chemo-immune-resistance. We propose aminobisphosphonates as new chemo-immune-sensitizing tools against drug-resistant osteosarcomas.

CD200fc enhances anti-tumoral immune response and inhibits visceral metastasis of breast carcinoma.

CD200 is a widely expressed cell surface glycoprotein that inhibits excessive inflammation in autoimmunity, transplantation, and viral infections. We previously observed that visceral metastasis of highly aggressive and inflammatory 4THM breast carcinoma cells was markedly decreased in CD200 transgenic mice. The goal of this study was to determine whether exogenous exposure to CD200fc mimics the effects of endogenously over expressed CD200. Female BALB/c mice were injected with CD200fc two times a week for five times. Injection was started two days after orthotopic injection of 4THM cells. Tumor infiltrating Gr1+Cd11b+ cells were decreased while CD8+ cells were increased in CD200fc-treated animals. CD200fc injection significantly decreased lung and liver metastasis and the growth of primary tumors. CD200fc injection enhanced the tumor-induced IFN-g response while suppressing the IL-10 response. We observed excessive basal IL-6 secretion in MLC which was significantly decreased in CD200fc treated mice 12 days after injection of 4TM cells. These results are in accord with previous data from CD200 transgenic mice, and demonstrate for the first time that CD200 analogues might have therapeutic potential in the treatment of aggressive breast carcinoma which induces excessive systemic inflammation.