Lung mesenchymal cells function as an inductive microenvironment for human lung cancer propagating cells†

Spatial architecture of tumour-infiltrating lymphocytes as a prognostic parameter in resected non-small-cell lung cancer

OBJECTIVES

Tumour-infiltrating lymphocytes (TILs) are critically implicated in the clinical outcome and response to immunotherapy in non-small-cell lung cancer (NSCLC) patients. The functional competence of lymphocyte subpopulations is strongly conditioned by their spatial arrangement within the tumour immune microenvironment. The aim of this study was to determine whether the tissue localization of specific TIL subpopulations might have an impact on the risk of recurrence in surgically resected NSCLC.

METHODS

High-speed scanning of whole slide images was performed on immunohistochemically stained tissue sections from 97 NSCLC patients to assess the number and ratio of CD3+, CD8+ and PD-1+ T-lymphocytes. TIL distribution was computed considering the intratumoural (proximal or distal) and peripheral (invasive margin) localization as well as their location within the fibrotic tissue (immune excluded). The tumour proliferative index was assessed by Ki67 labelling. The impact of TILs number and distribution on clinical-pathological characteristics and outcomes were statistically analysed.

RESULTS

High density and percentage of proximal CD8+ TILs and low PD-1-to-CD8 ratio had a positive impact on disease-free-survival (P = 0.03) and overall survival (P = 0.003). An inverse correlation was observed between the abundance of intratumoural CD8+ TILs carrying PD-1 inhibitory receptor and cancer cell proliferation. Cases with high compared to low fraction of immune excluded CD8+ TILs had significantly reduced 5-year overall survival (n events: 22 vs 12; P = 0.04) and disease-free survival (n events: 24 vs 16; P = 0.03) rates while the amount of CD3+ and CD8+ TILs located at the invasive margin had a favourable effect on the clinical course.

CONCLUSIONS

Mapping TIL subpopulations may implement the definition of prognostic parameters in surgically resected NSCLC.

Host CD39 Deficiency Affects Radiation-Induced Tumor Growth Delay and Aggravates Radiation-Induced Normal Tissue Toxicity

The ectonucleoside triphosphate diphosphohydrolase (CD39)/5′ ectonuclotidase (CD73)-dependent purinergic pathway emerges as promising cancer target. Yet, except for own previous work revealing a pathogenic role of CD73 and adenosine in radiation-induced lung fibrosis, the role of purinergic signaling for radiotherapy outcome remained elusive. Here we used C57BL/6 wild-type (WT), CD39 knockout (CD39^−/−), and CD73 knockout (CD73^−/−) mice and hind-leg tumors of syngeneic murine Lewis lung carcinoma cells (LLC1) to elucidate how host purinergic signaling shapes the growth of LLC1 tumors to a single high-dose irradiation with 10 Gy in vivo. In complementary in vitro experiments, we examined the radiation response of LLC1 cells in combination with exogenously added ATP or adenosine, the proinflammatory and anti-inflammatory arms of purinergic signaling. Finally, we analyzed the impact of genetic loss of CD39 on pathophysiologic lung changes associated with lung fibrosis induced by a single-dose whole-thorax irradiation (WTI) with 15 Gy. Loss of CD73 in the tumor host did neither significantly affect tumor growth nor the radiation response of the CD39/CD73-negative LLC1 tumors. In contrast, LLC1 tumors exhibited a tendency to grow faster in CD39^−/− mice compared to WT mice. Even more important, tumors grown in the CD39-deficient background displayed a significantly reduced tumor growth delay upon irradiation when compared to irradiated tumors grown on WT mice. CD39 deficiency caused only subtle differences in the immune compartment of irradiated LLC1 tumors compared to WT mice. Instead, we could associate the tumor growth and radioresistance-promoting effects of host CD39 deficiency to alterations in the tumor endothelial compartment. Importantly, genetic deficiency of CD39 also augmented the expression level of fibrosis-associated osteopontin in irradiated normal lungs and exacerbated radiation-induced lung fibrosis at 25 weeks after irradiation. We conclude that genetic loss of host CD39 alters the tumor microenvironment, particularly the tumor microvasculature, and thereby promotes growth and radioresistance of murine LLC1 tumors. In the normal tissue loss of host, CD39 exacerbates radiation-induced adverse late effects. The suggested beneficial roles of host CD39 on the therapeutic ratio of radiotherapy suggest that therapeutic strategies targeting CD39 in combination with radiotherapy have to be considered with caution.

The therapeutic potential of mesenchymal stem cells in lung cancer: benefits, risks and challenges

BACKGROUND

Lung cancer is one of the most challenging diseases to treat. In the past decades standard therapy including surgery, chemo- and radiation therapy, alone or in combination has not changed the high mortality rate and poor prognosis. In recent years, mesenchymal stem cells (MSCs) have emerged as putative therapeutic tools due to their intrinsic tumor tropism, anti-tumor and immunoregulatory properties. MSCs release biomolecules that are thought to exert the same beneficial effects as their cellular counterparts and, as such, they may offer practical possibilities of using MSC-secreted products. Owing to their innate affinity to home to tumor sites, MSCs have also gained interest as selective vehicles for the delivery of anti-cancer agents. However, MSCs are also known to confer pro-oncogenic effects, rendering them into double-sword weapons against neoplastic diseases.

CONCLUSIONS

Here, we present published data on the cell- and secretome-based therapeutic competences of MSCs, as well as on their potential as engineered delivery vectors for the treatment of lung cancer. Despite the controversial role of MSCs in the context of lung cancer therapy, current findings support hopeful perspectives to harness the potential of MSC-based regimens that may augment current treatment modalities in lung cancer.

Targeting the Immunomodulatory CD73/Adenosine System to Improve the Therapeutic Gain of Radiotherapy

Extracellular adenosine is a potent endogenous immunosuppressive mediator critical to the maintenance of homeostasis in various normal tissues including the lung. Adenosine is either released from stressed or injured cells or generated from extracellular adenine nucleotides by the concerted action of the ectoenzymes ectoapyrase (CD39) and 5′ ectonucleotidase (CD73) that catabolize ATP to adenosine. An acute CD73-dependent increase of adenosine in normal tissues mostly exerts tissue protective functions whereas chronically increased adenosine-levels in tissues exposed to DNA damaging chemotherapy or radiotherapy promote pathologic remodeling processes and fibrosis for example in the skin and the lung. Importantly, cancer cells also express CD73 and high CD73 expression in the tumor tissue has been linked to poor overall survival and recurrence free survival in patients suffering from breast and ovarian cancer. CD73 and adenosine support growth-promoting neovascularization, metastasis, and survival in cancer cells. In addition, adenosine can promote tumor intrinsic or therapy-induced immune escape by various mechanisms that dampen the immune system. Consequently, modulating CD73 or cancer-derived adenosine in the tumor microenvironment emerges as an attractive novel therapeutic strategy to limit tumor progression, improve antitumor immune responses, avoid therapy-induced immune deviation, and potentially limit normal tissue toxicity. However, the role of CD73/adenosine signaling in the tumor and normal tissue responses to radiotherapy and its use as therapeutic target to improve the outcome of radiotherapy approaches is less understood. The present review will highlight the dual role of CD73 and adenosine in tumor and tissue responses to radiotherapy with a special focus to the lung. It will also discuss the potential benefits and risks of pharmacologic modulation of the CD73/adenosine system to increase the therapeutic gain of radiotherapy or combined radioimmunotherapy in cancer treatment.

Can Youthful Mesenchymal Stem Cells from Wharton's Jelly Bring a Breath of Fresh Air for COPD?

Chronic obstructive pulmonary disease (COPD) is a major global cause of morbidity and mortality, projected to become the 3rd cause of disease mortality worldwide by 2020. COPD is characterized by persistent and not fully reversible airflow limitation that is usually progressive and is associated with an abnormal chronic inflammatory response of the lung to noxious agents including cigarette smoke. Currently available therapeutic strategies aim to ease COPD symptoms but cannot prevent its progress or regenerate physiological lung structure or function. The urgently needed new approaches for the treatment of COPD include stem cell therapies among which transplantation of mesenchymal stem cells derived from Wharton’s jelly (WJ-MSCs) emerges as a promising therapeutic strategy because of the unique properties of these cells. The present review discusses the main biological properties of WJ-MSCs pertinent to their potential application for the treatment of COPD in the context of COPD pathomechanisms with emphasis on chronic immune inflammatory processes that play key roles in the development and progression of COPD.

Nigericin decreases the viability of multidrug-resistant cancer cells and lung tumorspheres and potentiates the effects of cardiac glycosides

Multiple factors including tumor heterogeneity and intrinsic or acquired resistance have been associated with drug resistance in lung cancer. Increased stemness and the plasticity of cancer cells have been identified as important mechanisms of resistance; therefore, treatments targeting cancer cells independent of stemness phenotype would be much more effective in treating lung cancer. In this article, we have characterized the anticancer effects of the antibiotic Nigericin in cells displaying varying degrees of stemness and resistance to anticancer drugs, arising from (1) routine culture conditions, (2) prolonged periods of serum starvation. These cells are highly resistant to conventional anticancer drugs such as Paclitaxel, Hydroxyurea, Colchicine, Obatoclax, Wortmannin, and LY294002, and the multidrug-resistant phenotype of cells growing under prolonged periods of serum starvation is likely the result of extensive rewiring of signaling pathways, and (3) lung tumorspheres that are enriched for cancer stem-like cells. We found that Nigericin potently inhibited the viability of cells growing under routine culture conditions, prolonged periods of serum starvation, and lung tumorspheres. In addition, we found that Nigericin downregulated the expression of key proteins in the Wnt canonical signaling pathway such as LRP6, Wnt5a/b, and β-catenin, but promotes β-catenin translocation into the nucleus. The antitumor effects of Nigericin were potentiated by the Wnt activator HLY78 and by therapeutic levels of the US Food and Drug Administration–approved drug Digitoxin and its novel synthetic analog MonoD. We believe that Nigericin may be used in a co-therapy model in combination with other novel chemotherapeutic agents in order to achieve potent inhibition of cancers that display varying degrees of stemness, potentially leading to sustained anticancer effects.

Combination of Gefitinib and Pemetrexed Prevents the Acquisition of TKI Resistance in NSCLC Cell Lines Carrying EGFR-Activating Mutation

INTRODUCTION

Development of resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors is a clinical issue in patients with epidermal growth factor receptor gene (EGFR)-mutated non-small cell lung cancer (NSCLC). The aim of this study was to investigate the potential of combining gefitinib and pemetrexed in preventing the acquisition of resistance to EGFR tyrosine kinase inhibitors in NSCLC cell lines harboring EGFR exon 19 deletion.

METHODS

The effect of different combinatorial schedules of gefitinib and pemetrexed on cell proliferation, cell cycle, apoptosis, and acquisition of gefitinib resistance in PC9 and HCC827 NSCLC cell lines and in PC9 xenograft models was investigated.

RESULTS

Simultaneous treatment with gefitinib and pemetrexed enhanced cell growth inhibition and cell death and prevented the appearance of gefitinib resistance mediated by T790M mutation or epithelial-to-mesenchymal transition (EMT) in PC9 and HCC827 cells, respectively. In PC9 cells and in PC9 xenografts the combination of gefitinib and pemetrexed, with different schedules, prevented gefitinib resistance only when pemetrexed was the first treatment, given alone or together with gefitinib. Conversely, when gefitinib alone was administered first and pemetrexed sequentially alternated, a negative interaction was observed and no prevention of gefitinib resistance was documented. The mechanisms of resistance that developed in vivo included T790M mutation and EMT. The induction of EMT was a feature of tumors treated with gefitinib when given before pemetrexed, whereas T790M was recorded only in tumors treated with gefitinib alone.

CONCLUSIONS

The combination of gefitinib and pemetrexed is effective in preventing gefitinib resistance; the application of intermittent treatments requires that gefitinib not be administered before pemetrexed.

Secretome of human bone marrow mesenchymal stem cells: an emerging player in lung cancer progression and mechanisms of translation initiation

Non-small cell lung cancer (NSCLC) remains the most common cause of cancer-related death worldwide. Patients presenting with advanced-stage NSCLC have poor prognosis, while metastatic spread accounts for >70 % of patient's deaths. The major advances in the treatment of lung cancer have brought only minor improvements in survival; therefore, novel strategic treatment approaches are urgently needed. Accumulating data allocate a central role for the cancer microenvironment including mesenchymal stem cells (MSCs) in acquisition of drug resistance and disease relapse. Furthermore, studies indicate that translation initiation factors are over expressed in NSCLC and negatively impact its prognosis. Importantly, translation initiation is highly modulated by microenvironmental cues. Therefore, we decided to examine the effect of bone marrow MSCs (BM-MSCs) from normal donors on NSCLC cell lines with special emphasis on translation initiation mechanism in the crosstalk. We cultured NSCLC cell lines with BM-MSC conditioned media (i.e., secretome) and showed deleterious effects on the cells' proliferation, viability, death, and migration. We also demonstrated reduced levels of translation initiation factors implicated in cancer progression [eukaryotic translation initiation factor 4E (eIF4E) and eukaryotic translation initiation factor 4GI (eIF4GI)], their targets, and regulators. Finally, we outlined a mechanism by which BM-MSCs' secretome affected NSCLC's mitogen-activated protein kinase (MAPK) signaling pathway, downregulated the cell migration, and diminished translation initiation factors' levels. Taken together, our study demonstrates that there is direct dialogue between the BM-MSCs' secretome and NSCLC cells that manipulates translation initiation and critically affects cell fate. We suggest that therapeutic approach that will sabotage this dialogue, especially in the BM microenvironment, may diminish lung cancer metastatic spread and morbidity and improve the patient's life quality.

[Advances in Lung Stem Cells and Lung Cancer Stem Cells]

癌干细胞是目前癌症研究的热点之一。肺癌干细胞与正常肺干细胞有许多共同之处, 包括自我更新能力和多分化潜能。许多癌干细胞分子标志为肺癌干细胞所共有, 如CD133、CD44、乙醛脱氢酶(aldehyde dehydrogenase, ALDH)以及ATP结合转运蛋白G超家族成员2(ATP-binding cassette sub-family G member 2, ABCG2)。肺癌干细胞的扩增与作用不仅受胚胎干细胞途径如Notch、Hedgehog和Wnt调控, 也受肿瘤信号途径如表皮生长因子受体(epidermal growth factor receptor, EGFR)、信号传导转录激活因子3(signal transducer and activator of transcription 3, STAT3)和磷脂酰肌醇3激酶(phosphatidylinositol 3 kinase, PI3K)等的调控。由于癌干细胞在肿瘤复发、转移和耐药性等方面发挥着重要作用, 揭示肺癌干细胞与正常干细胞的区别, 鉴定并靶向癌干细胞特异性表面标志物及其介导的信号通路, 将有望改善肺癌治疗效果和提高患者生存率。

Drug-releasing mesenchymal cells strongly suppress B16 lung metastasis in a syngeneic murine model

BACKGROUND

Mesenchymal stromal cells (MSCs) are considered an important therapeutic tool in cancer therapy. They possess intrinsic therapeutic potential and can also be in vitro manipulated and engineered to produce therapeutic molecules that can be delivered to the site of diseases, through their capacity to home pathological tissues. We have recently demonstrated that MSCs, upon in vitro priming with anti-cancer drug, become drug-releasing mesenchymal cells (Dr-MCs) able to strongly inhibit cancer cells growth.

METHODS

Murine mesenchymal stromal cells were loaded with Paclitaxel (Dr-MCsPTX) according to a standardized procedure and their ability to inhibit the growth of a murine B16 melanoma was verified by in vitro assays. The anti-metastatic activity of Dr-MCsPTX was then studied in mice injected i.v. with B16 melanoma cells that produced lung metastatic nodules. Lung nodules were counted under a dissecting stereomicroscope and metastasis investigated by histological analysis.

RESULTS

We found that three i.v. injections of Dr-MCsPTX on day 5, 10 and 15 after tumor injection almost completely abolished B16 lung metastasis. Dr-MCsPTX arrested into lung by interacting with endothelium and migrate toward cancer nodule through a complex mechanism involving primarily mouse lung stromal cells (mL-StCs) and SDF-1/CXCR4/CXCR7 axis.

CONCLUSIONS

Our results show for the first time that Dr-MCsPTX are very effective to inhibit lung metastasis formation. Actually, a cure for lung metastasis in humans is mostly unlikely and we do not know whether a therapy combining engineered MSCs and Dr-MCs may work synergistically. However, we think that our approach using Dr-MCs loaded with PTX may represent a new valid and additive therapeutic tool to fight lung metastases and, perhaps, primary lung cancers in human.