COPD-Type lung inflammation promotes K-ras mutant lung cancer through epithelial HIF-1α mediated tumor angiogenesis and proliferation

Chronic obstructive pulmonary disease (COPD), an inflammatory disease of the lung, is an independent risk factor for lung cancer. Lung tissues obtained from human smokers with COPD and lung cancer demonstrate hypoxia and up-regulated hypoxia inducible factor-1 (HIF-1). HIF-1 activation is the central mechanism for controlling the cellular response to hypoxia during inflammation and tumor development. These facts suggest a link between COPD-related airway inflammation, HIF-1, and lung cancer. We have previously established a mouse model of COPD-like airway inflammation that promotes lung cancer in a K-ras mutant mouse model (CC-LR). Here we show that tumors in the CC-LR model have significantly elevated levels of HIF-1α and HIF-1 activity. To determine the tumor-promoting functions of HIF-1 in CC-LR mice, the gene Hif1a which encodes HIF-1α and is required for HIF-1 activity, was disrupted in the lung epithelium of CC-LR animals. Airway epithelial specific HIF-1α deficient mice demonstrated significant reductions in lung surface tumor numbers, tumor angiogenesis, and tumor cell proliferation in the absence or presence of COPD-like airway inflammation. In addition, when CC-LR mice were bred with transgenic animals that overexpress a constitutively active mutant form of human HIF-1α in the airway epithelium, both COPD- and adenocarcinoma-like phenotypes were observed. HIF-1α overexpressing CC-LR mice had significant emphysema, and they also showed potentiated tumorigenesis, angiogenesis, and cell proliferation accompanied by an invasive metastatic phenotype. Our gain and loss of function studies support a key role for HIF-1α in the promotion of lung cancer by COPD-like inflammation.

Requirement for MUC5AC in KRAS-dependent lung carcinogenesis

With more than 150,000 deaths per year in the US alone, lung cancer has the highest number of deaths for any cancer. These poor outcomes reflect a lack of treatment for the most common form of lung cancer, non-small cell lung carcinoma (NSCLC). Lung adenocarcinoma (ADC) is the most prevalent subtype of NSCLC, with the main oncogenic drivers being KRAS and epidermal growth factor receptor (EGFR). Whereas EGFR blockade has led to some success in lung ADC, effective KRAS inhibition is lacking. KRAS-mutant ADCs are characterized by high levels of gel-forming mucin expression, with the highest mucin levels corresponding to worse prognoses. Despite these well-recognized associations, little is known about roles for individual gel-forming mucins in ADC development causatively. We hypothesized that MUC5AC/Muc5ac, a mucin gene known to be commonly expressed in NSCLC, is crucial in KRAS/Kras-driven lung ADC. We found that MUC5AC was a significant determinant of poor prognosis, especially in patients with KRAS-mutant tumors. In addition, by using mice with lung ADC induced chemically with urethane or transgenically by mutant-Kras expression, we observed significantly reduced tumor development in animals lacking Muc5ac compared with controls. Collectively, these results provide strong support for MUC5AC as a potential therapeutic target for lung ADC, a disease with few effective treatments.

IL22 Promotes Kras-Mutant Lung Cancer by Induction of a Protumor Immune Response and Protection of Stemness Properties

Somatic KRAS mutations are the most common oncogenic variants in lung cancer and are associated with poor prognosis. Using a Kras-induced lung cancer mouse model, CC-LR, we previously showed a role for inflammation in lung tumorigenesis through activation of the NF-κB pathway, along with induction of interleukin 6 (IL6) and an IL17-producing CD4+ T-helper cell response. IL22 is an effector molecule secreted by CD4+ and γδ T cells that we previously found to be expressed in CC-LR mice. IL22 mostly signals through the STAT3 pathway and is thought to act exclusively on nonhematopoietic cells with basal IL22 receptor (IL22R) expression on epithelial cells. Here, we found that higher expression of IL22R1 in patients with KRAS-mutant lung adenocarcinoma was an independent indicator of poor recurrence-free survival. We then showed that genetic ablation of Il22 in CC-LR mice (CC-LR/IL22KO mice) caused a significant reduction in tumor number and size. This was accompanied by significantly lower tumor cell proliferation, angiogenesis, and STAT3 activation. Il22 ablation was also associated with significant reduction in lung-infiltrating inflammatory cells and expression of protumor inflammatory cytokines. Conversely, this was accompanied with increased antitumor Th1 and cytotoxic CD8+ T-cell responses, while suppressing the protumor immunosuppressive T regulatory cell response. In CC-LR/IL22KO mice, we found significantly reduced expression of core stemness genes and the number of prototypical SPC+CCSP+ stem cells. Thus, we conclude that IL22 promotes Kras-mutant lung tumorigenesis by driving a protumor inflammatory microenvironment with proliferative, angiogenic, and stemness contextual cues in epithelial/tumor cells. Cancer Immunol Res; 6(7); 788-97. ©2018 AACR.

Abstract 2679: A promoting role for the epithelial MyD88/IRAK4/NF-kB signaling in K-ras mutant lung tumorigenesis

K-ras mutation is the most common oncogenic alterations associated with lung cancer development. Unfortunately, all attempts to develop therapies directly targeting K-ras have been failed thus far, clearly stating the need for new strategies targeting downstream effectors and/or cooperating pathways of K-ras to overcome lung cancer displaying such a molecular profile. Using a conditional K-ras mutated lung cancer mouse model, CC-LR (CCSPcre/LSL-K-rasG12D) we previously showed that K-ras mutated lung tumorigenesis is associated with lung inflammation due to activation of NF-κB pathway and increased expression of its downstream targets in the lung. Here we have shown that lack of NF-κB activity in the airway epithelium by selectively targeting IKKβ, which is required for NF-kB activation, significantly reduces lung tumor burden (3.4-fold) and changes the inflammatory cells and mediators in the bronchoalveolar lavage fluid (BALF) of CC-LR mice. Immunohistochemically staining of lung tissues with specific markers, Ki-67 and CD-31, demonstrated significantly lower tumor cell proliferation and angiogenesis in CC-LR mice with lack of epithelial NF-kB activity. To further dissect the role of NF-κB pathway in this process, CC-LR mice were crossed with MyD88f/f mice to develop a mouse with lack of MyD88 (an adaptor protein upstream to IKKβ) in the airway epithelial cells (CC-LR/MyD88Δ/Δ mice). As we had hypothesized, the resulting tumor numbers in the lungs were significantly lower (1.9-fold) in CC-LR mice with lack of MyD88 in the airway epithelial cells compared to control CC-LR mice. Tumor reduction in CC-LR-MyD88Δ/Δ mice was also associated with decreased tumor cell proliferation and angiogenesis compared to control CC-LR mice. Surprisingly, unlike to lack of epithelial NF-kB activity, absence of MyD88 in the airway epithelium did not change the BALF inflammatory cell component of CC-LR mice. We then targeted another upstream signaling molecule to NF-kB, IRAK4, which is down stream of MyD88 by crossing CC-LR mice to IRAK4 knock out mice. Similar to lack of MyD88, we found a significant reduction in lung tumor number (1.8-fold) with no changes in BALF inflammatory cell component in CC-LR mice with lack of IRAK4 compared to the control CC-LR mice. Taken these together, we conclude that there is an essential role for MyD88/IRAK4/NF-kB pathway activation in promotion of K-ras mutant lung cancer.

Citation Format: Susana Castro, Soudabeh Daliri, Maria Miguelina De La Garza, Amber M. Cumpian, Misha Umer, Diana Del Bosque, Sabah Akbani, Scott E. Evans, Seyed Javad Moghaddam. A promoting role for the epithelial MyD88/IRAK4/NF-kB signaling in K-ras mutant lung tumorigenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2679. doi:10.1158/1538-7445.AM2017-2679

Abstract 3714: Muc5ac plays an essential role in promotion of k-ras mutant lung cancer

Worldwide, lung cancer is the leading cause of cancer mortality, and cigarette smoking (CS) is its principal cause. However, several studies have found that smokers with chronic obstructive pulmonary disease (COPD), an inflammatory disease of the lung, have an increased risk of lung cancer (3 to 10-fold) compared to smokers with comparable cigarette exposure but without COPD. Importantly, among smokers with COPD, even following withdrawal of cigarette smoke, inflammation persists and lung function continues to deteriorate as does the increased risk of lung cancer. These facts suggest a strong link between COPD-related lung inflammation and lung cancer, however, the precise mechanistic link is not known. Mucociliary dysfunction and mucin hyperproduction are important features of COPD with inflammation being the major trigger. Interestingly, lung cancer with mucin overexpression has higher malignancy potential and poor prognosis, which around 76% having mutations in K-ras oncogene, the most frequent oncogenic mutation in lung adenocarcinoma. Taken these together, we hypothesized that mucins contribute to promotion of K-ras mutant lung cancer by inflammation. Here we first investigated whether Muc5ac, predominant airway mucin that plays a primary role in inflammatory lung diseases, is predictive of clinical outcome in KRAS-mutant human lung adenocarcinomas. We determined Muc5ac mRNA expression by array analysis of 150 lung adenocarcinomas from patients that did not received neoadjuvant therapy and we found that, Muc5ac mRNA level was a significant predictor of poor disease-free survival in KRAS-mutant lung adenocarcinomas. We have further found increased mucin and high expression of Muc5ac in lung tumor tissues of the mice with airway specific expression of a mutant form of K-ras (CC-LR mice). Then, we crossed previously developed Muc5ac knockout (KO) mice to CC-LR mice in order to develop a K-ras mutant lung cancer mouse model with lack of Muc5ac (CC-LR/Muc5ac KO mice). This resulted in a significant tumor reduction by ~54% (2.2-fold) in lung of CC-LR/Muc5ac KO mice compared to age and sex matched control CC-LR mice. Lung inflammation was evaluated by analysis of bronchoalveolar lavage fluid and revealed a significant reduction (3-fold) in number of macrophages, and levels of IL-6 and IL-17 in CC-LR/Muc5ac KO mice compared to CC-LR control mice. Immunohistopathological analysis of lung sections confirmed lower inflammation, decreased tumor number and size, less adenomatous lesions, and reduced tumor cell proliferation and angiogenesis in CC-LR mice with lack of Muc5ac compared to control CC-LR mice. Our experimental results suggest that Muc5ac has an essential role in promotion of K-ras mutant lung cancer through autocrine cell intrinsic and paracrine immune cell mediated mechanisms.

Citation Format: Misha Umer, Amber M. Cumpian, Nasim Khosravi, Zoulikha Azzegagh, Maede Mohebnasab, Mauricio S. Caetano, Edwin J. Ostrin, Ignacio I. Wistuba, Burton Dickey, Humam Kadara, Christopher M. Evans, Seyed J. Moghaddam. Muc5ac plays an essential role in promotion of k-ras mutant lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3714. doi:10.1158/1538-7445.AM2017-3714

Tumor necrosis factor links chronic obstructive pulmonary disease and K-ras mutant lung cancer through induction of an immunosuppressive pro-tumor microenvironment

Tumor necrosis factor (TNF) is known as an important regulator of tumor microenvironment and inflammation. TNF levels are markedly elevated in the bronchoalveolar lavage fluid (BALF) of patients with chronic obstructive pulmonary disease (COPD), which is an independent risk factor for lung cancer. We have previously shown that COPD-like airway inflammation promotes lung cancer in a K-ras mutant mouse model (CC-LR mouse). This was associated with a significant increase of neutrophils in BALF, accompanied by a marked increase in TNF level, suggesting a link between COPD, TNF, and lung cancer promotion. Therefore, we first overexpressed TNF in the airway epithelium of CC-LR mice, which promoted lung cancer by ∼2-fold. This was associated with increased numbers of Ki67 and CD31 positive cells in lung tumors of CC-LR/TNF-Tg mice. We also found a robust increase in NF-κB activation, and numbers of neutrophils and myeloid-derived suppressor cells (MDSCs) in lung. Accordingly, we depleted MDSCs in CC-LR/TNF-Tg mice, which lead to significant tumor suppression emphasizing on the role of TNF-induced MDSCs in K-ras induced lung tumorigenesis. Finally, we targeted TNF expression by crossing CC-LR mice with TNF knock-out mice (CC-LR/TNF-KO), which resulted in a significant decrease in lung tumor burden in the absence or presence of COPD-like airway inflammation. Interestingly, there were less MDSCs and lower Ki67 and CD31 expression in the lung of the CC-LR/TNF-KO mice. We conclude that TNF links COPD to lung cancer promotion by induction of an immunosuppressive MDSC response, and subsequent amplification of proliferation and angiogenesis in tumors.

Abstract 4398: Impact of Interleukin-22 on K-ras mutant lung tumor microenvironment and stemness properties

Oncogenic K-ras mutations found in ∼ 30% of all non-small cell lung cancers are associated with chemoresistance and poor prognosis. Using a K-ras induced lung cancer mouse model, CC-LR, we previously showed that K-ras mutant lung tumors have intrinsic inflammatory characteristics with activation of NF-kB pathway, release of inflammatory cytokines IL-6, and activation of the IL-6 responsive transcription factor STAT3. We have further shown that IL-6/STAT3 pathway, and IL-17 producing CD4 helper T cells (Th17 cells) through their main cytokine, IL-17A, play critical roles in promotion of lung cancer in this model. IL-22 is another effecter molecule secreted by Th17 cells which is highly expressed in our K-ras mutant mouse model. IL-22 is a unique cytokine, which seems to act exclusively on nonhematopoietic cells, with basal IL-22R expression in the epithelial cells and fibroblast, and mostly signals through STAT3 pathway. Here we found that genetic ablation of IL-22 in CC-LR mice (CC-LR/IL22-KO mice), causes significant reduction in lung surface tumor numbers by ∼54% (2.1-fold). Histopathological analysis of lung sections confirmed a reduction in number and size of tumors in CC-LR/IL22-KO mice, which was associated with significantly lower tumor cell proliferation, angiogenesis and STAT3 activation. IL-22 ablation also reduced the numbers of inflammatory cells in bronchoalveolar lavage fluid, and decreased the expression of pro-tumor inflammatory cytokines such as IL-6, IL-17 and TNFα. This was associated with increased expression of anti-tumor Th1 cells -specific transcription factor (Tbet) and their activation markers, IFNγ, and GZB, and decreased expression of pro-tumor Th17- (RORγ) and T regulatory (FOXP3+) specific transcription factors. Recent studies have shown an association between IL-22 and stem-cell like properties in colon cancer. In lung cancer, cell populations expressing NANOG, SOX2, Oct4 and/or aldehyde dehydrogenase activity are enriched with stemness properties. Interestingly, in CC-LR/IL22-KO mice we found significant reduction in expression of these stemness genes. Thus, we conclude that IL-22 promotes K-ras mutant lung tumorigenesis by inducing a pro-tumor inflammatory microenvironment with proliferative and angiogenic properties as well as protecting stemness characteristic in epithelial/tumor cells. Therefore, we propose pharmacological targeting of IL-22 as a potential therapeutic strategy in combination with conventional cytotoxic therapy, immune check point blockade, or other targeted therapies (e.g. MEK inhibition) for lung cancer patients with K-ras mutation.

Citation Format: Nasim Khosravi, Amber M. Cumpian, Soudabeh Daliri, Cynthia De La Garza, Mauricio S. Caetano, Seyed Javad Moghaddam. Impact of Interleukin-22 on K-ras mutant lung tumor microenvironment and stemness properties. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4398.

IL6 Blockade Reprograms the Lung Tumor Microenvironment to Limit the Development and Progression of K-ras-Mutant Lung Cancer

Activating mutations of K-ras are the most common oncogenic alterations found in lung cancer. Unfortunately, attempts to target K-ras-mutant lung tumors have thus far failed, clearly indicating the need for new approaches in patients with this molecular profile. We have previously shown NF-κB activation, release of IL6, and activation of its responsive transcription factor STAT3 in K-ras-mutant lung tumors, which was further amplified by the tumor-enhancing effect of chronic obstructive pulmonary disease (COPD)-type airway inflammation. These findings suggest an essential role for this inflammatory pathway in K-ras-mutant lung tumorigenesis and its enhancement by COPD. Therefore, here we blocked IL6 using a monoclonal anti-IL6 antibody in a K-ras-mutant mouse model of lung cancer in the absence or presence of COPD-type airway inflammation. IL6 blockade significantly inhibited lung cancer promotion, tumor cell-intrinsic STAT3 activation, tumor cell proliferation, and angiogenesis markers. Moreover, IL6 inhibition reduced expression of protumor type 2 molecules (arginase 1, Fizz 1, Mgl, and IDO), number of M2-type macrophages and granulocytic myeloid-derived suppressor cells, and protumor T-regulatory/Th17 cell responses. This was accompanied by increased expression of antitumor type 1 molecule (Nos2), and antitumor Th1/CD8 T-cell responses. Our study demonstrates that IL6 blockade not only has direct intrinsic inhibitory effect on tumor cells, but also reeducates the lung microenvironment toward an antitumor phenotype by altering the relative proportion between protumor and antitumor immune cells. This information introduces IL6 as a potential druggable target for prevention and treatment of K-ras-mutant lung tumors. Cancer Res; 76(11); 3189-99. ©2016 AACR.

Abstract 413: Targeting IL-6 as a preventive and therapeutic strategy for K-ras mutant lung cancer

Worldwide, lung cancer (LC) leads in cancer mortality and cigarette smoking (CS) is its principal cause. Activating mutations of K-ras are one of the most common alterations in LC and are associated with CS exposure. However, several studies have shown that smokers with chronic obstructive pulmonary disease (COPD), an inflammatory disease of the lung, have a higher risk of developing LC when compared to smokers without COPD. These facts suggest a strong link between COPD-type inflammatory lung microenvironment and K-ras mutant lung cancer. Unfortunately, attempts to directly target K-ras have thus far failed, clearly stating the need for new approaches to bring clinical benefits to patients with this undrugabble profile. Using a conditional K-ras induced lung cancer mouse model (CC-LR) we showed that K-ras mutant lung tumors have intrinsic inflammatory characteristics, and a bacterial lysate-induced COPD-like airway inflammation promotes lung cancer in this model. This was associated with release of the cytokine IL-6 and activation of the IL-6-responsive transcription factor STAT3. We showed that genetic ablation of IL-6 in this model results in a significant tumor reduction indicating an essential role for IL-6/STAT3 pathway in lung cancer promotion and introducing IL-6 as a druggable target for K-ras mutant lung tumor. Therefore, we blocked IL-6 using a monoclonal anti-IL-6 immunotherapy in our K-ras mutant model. Six week old CC-LR mice were injected intraperitoneally with 20 mg/kg dose of an anti-IL-6 monoclonal IgG1 antibody twice a week for eight weeks, while been exposed to the aerosolized bacterial lysate once weekly for 8 weeks. Anti-IL-6 therapy not only inhibited intrinsic lung cancer development by ∼78%, but also inhibited the tumor promoting effect of the COPD-like airway inflammation. It also decreased the expression of P-STAT3, proliferation marker, Ki67, and pro-angiogenic factors: VEGF, MMP-9 and CD31 in lung tissue. qPCR analysis of lung tissues from anti-IL-6 treated mice showed a decrease in Arginase1, FIZZ1, FOXP3, and IL-17 expression, with increased expression of Th1 markers, IFNγ and TBx21. Flow cytometry analysis of total lung inflammatory cells in CC-LR mouse showed a significant increase in the population of tumor associated macrophages (TAMs) during tumor progression from age 6 to 14 weeks, and COPD-like inflammation induced an increase in myeloid derived suppressor cell (MDSCs) population. Interestingly, we found a significant decrease in TAMs and MDSCs population after anti-IL-6 treatment. Taken together, we conclude that IL-6 blockade not only has cell intrinsic effect in K-ras mutant tumors but also edit the lung microenvironment toward an anti-tumor phenotype. Therefore, we propose pharmacological targeting of IL-6 alone or in combination with conventional cytotoxic therapy, or other targeted therapies for prevention and treatment of lung cancer patients with K-ras mutation.

Citation Format: Mauricio S. Caetano, Amber M. Cumpian, Lei Gong, Seon H. Chang, Huiyuan Zhang, Humam N. Kadara, Cinthya Sternberg, Carlos G. Ferreira, Stephanie S. Watowich, Seyed J. Moghaddam. Targeting IL-6 as a preventive and therapeutic strategy for K-ras mutant lung cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 413. doi:10.1158/1538-7445.AM2015-413

Abstract B43: Targeting tumor microenvironment for treatment of K-ras mutant lung cancer

Activating mutations of K-ras are one of the most common molecular alterations associated with lung cancer development. Several attempts to develop therapies directly targeting K-ras have been failed thus far, clearly state the need for new strategies to bring clinical benefits to patients displaying such a molecular profile. Using a conditional K-ras mutant lung cancer mouse model (CC-LR) we previously showed that K-ras mutated lung tumors have intrinsic inflammatory characteristics associated with NF-κB pathway activation. Therefore, CC-LR mice were crossed with IKK-β f/f mice to develop a K-ras mutant mouse with lack of NF-κB activity in airway epithelium. This changed the bronchoalveolar lavage fluid (BALF) cellular component of the CC-LR mice (mostly by reduction of macrophages), and resulted in a ∼70% (3.4-fold) reduction in lung surface tumor number. Lung of CC-LR mice also shows high protein level of IL-6 (downstream to NF-κB activation) and increased STAT3 gene expression (downstream signal to IL-6) plus infiltration of myeloid and Th17 cells. Accordingly, we genetically ablated IL-6 in the CC-LR mice. This significantly inhibited lung cancer development (1.7-fold, 41%) suggesting a role for IL-6 mediated signaling in tumor promotion probably through STAT3 pathway activation. IL-6 and STAT3 are required for differentiation of Th17 cells from naïve T cells. Th17 cells mostly produce IL-17A that binds to the IL-17 receptor (IL-17R). IL-17R signaling is required for lung CXC chemokine expression and myeloid cell recruitment. Furthermore, IL-17A induces more production of IL-6 by epithelial cells. So, CC-LR mice were crossed with IL-17A KO mice. Lack of IL-17A in CC-LR mice resulted in a ∼70% (3.4-fold) tumor reduction. It also decreased the expression of pro-inflammatory mediators and reduced recruitment of myeloid cells. These reults suggest that K-ras initiated airway inflammation through NF-κB mediated activation of the IL-6/STAT3/Th17 signaling promotes lung tumorigenesis, and introduce IL-6 as a potential druggable target for lung cancer patients who harbor K-ras mutations. This prompted us to block IL-6 pathway using a monoclonal anti-IL-6 immunotherapy in our K-ras mutant model. Six week old CC-LR mice were injected intraperitoneally with 20 mg/kg dose of an anti-IL-6 monoclonal IgG1 antibody, twice a week, for a period of 8 weeks. Flowcytometry and qPCR analysis of total lung in non-treated CC-LR mice showed 2-fold increase in the population of tumor associated macrophage (TAM) and Arginase-1 mRNA expression (3 fold) during tumor progression from age 6 weeks to 14 weeks suggesting that epithelial signal initiated by K-ras mutation dictates an inflammatory type 2 pro-tumor fate for lung microenvironment. We further found that anti-IL-6 treatment suppressed tumor development by ∼78% (4.6-fold) in CC-LR mice with a significant reduction in the expression levels of Ki-67, VEGF, MMP9, CD31 and phospho-STAT3 in lung tissue. It also reduced TGFβ and KC protein levels in BALF with a significant decrease in Arginase1 mRNA expression (3-fold) and TAM population (5-fold) in total lung homogenate. We conclude that K-ras mutation drives an immunosuppressive pro-tumor response and blocking IL-6 shifts this to an anti-tumor lung microenvironment. Therefore we propose pharmacological targeting of IL-6 as a potential therapeutic strategy alone or in combination with conventional cytotoxic therapy for lung cancer patients with K-ras mutation.

Funded by: American Cancer Society, RSG-11-115-01-CNE, and American Lung Association/LUNGevity Foundation, LCD-114696-N

Citation Format: Mauricio da Silva Caetano, Seon Hee Chang, Amber M. Cumpian, Soudabeh Daliri, Maria Miguelina De La Garza, Cesar E. Ochoa, Chen Dong, Seyed Javad Moghaddam. Targeting tumor microenvironment for treatment of K-ras mutant lung cancer. [abstract]. In: Proceedings of the AACR Special Conference on RAS Oncogenes: From Biology to Therapy; Feb 24-27, 2014; Lake Buena Vista, FL. Philadelphia (PA): AACR; Mol Cancer Res 2014;12(12 Suppl):Abstract nr B43. doi: 10.1158/1557-3125.RASONC14-B43

Abstract A13: Pharmacologic targeting of IL-6 suppresses tumor progression in a non-small cell lung cancer mouse model with K-ras mutation through re-educating the tumor microenvironment

Activating mutations of K-ras are one of the most common molecular alterations associated with lung cancer development. Several attempts to develop therapies directly targeting K-ras have failed thus far, clearly state the need for new strategies to bring clinical benefits to patients displaying such molecular profile. Using a conditional K-ras mutated lung cancer mouse model (CC-LR) we previously showed that K-ras mutated lung tumors have intrinsic inflammatory characteristics and we also demonstrated that chronic obstructive pulmonary disease (COPD)-like airway inflammation, an independent risk factor for lung cancer, promotes lung tumor in this model. CC-LR mice shows high protein level of interleukin 6 (IL-6) and increased STAT3 (downstream signal to IL6) gene expression, and we have further shown that genetic ablation of IL-6 in CC-LR mice results in significant tumor reduction. High levels of IL-6 and up-regulation of STAT3 and its target genes have been observed in the lungs of smokers with COPD, and in 50% of human lung adenocarcinomas. These indicate an essential role for IL-6 in lung cancer promotion, and introduce IL-6 as a potential druggable target for lung cancer patients who harbor K-ras mutations. This prompted us to block IL-6 pathway using a monoclonal anti-IL-6 immunotherapy in our K-ras mutated lung cancer mouse model. Six week old CC-LR mice were injected intraperitoneally (I.P.) with 20 mg/kg dose of an anti-IL-6 monoclonal IgG1 antibody, twice a week, for a period of eight weeks. Flowcytometry analysis of total lung inflammatory cell population in non-treated CC-LR mice showed 2-fold increase in the population of tumor associated macrophage (TAM) (CD45+/CD11b+/GR1+/F4/80+/MCSFR+) during tumor progression from age 6 weeks to 14 weeks. qPCR analysis of total lung RNA from non-treated CC-LR mice showed that there is an increase in the level of Arginase-1 (3 fold) with no change in the level of inducible Nitric Oxide Synthetize (NOS2). This suggests that epithelial signal initiated by K-ras mutation may dictate the fate of lung microenvironment by creating an inflammatory pro-tumor type 2 response. Then we found that anti-IL-6 treatment suppresses tumor progression by ~78% (4.6-fold) in CC-LR mice which is associated with a significant reduction in the quantity of inflammatory cells in bronchoalveolar lavage fluid (BALF). It also decreased the expression of proliferation marker: Ki-67, and pro angiogenic factors: VEGF, MMP9 and CD31 and phospho-STAT3 in lung tissue. ELISA analysis of BALF from CC-LR mice also showed that anti-IL-6 treatment reduces TGFβ and KC protein levels with no change in level of IL-17. qPCR and flowcytometry analysis of total lung homogenate of CC-LR mice further showed that IL-6 blockade induces a significant decrease in Arginase1 expression (3-fold) and TAM population (5-fold). Taking together here we showed that K-ras mutated lung tumor drives an immunosuppressive pro-tumor microenvironment, with an M2 TAM polarization and blocking the suppressive actions of IL-6 shifts this to an anti-tumor lung microenvironment. Therefore we propose pharmacological targeting of IL-6 as a potential therapeutic strategy alone or in combination with conventional cytotoxic therapy for lung cancer patients with K-ras mutation.

Funded by: American Cancer Society, RSG-11-115-01-CNE, and American Lung Association/LUNGevity Foundation, LCD-114696-N

Citation Format: Mauricio S. Caetano, Amber M. Cumpian, Lei Gong, Cesar E. Ochoa, Seon H. Chang, Huiyuan Zhang, Stephanie Watowich, Cinthya Sternberg, Carlos G. Ferreira, Seyed J. Moghaddam. Pharmacologic targeting of IL-6 suppresses tumor progression in a non-small cell lung cancer mouse model with K-ras mutation through re-educating the tumor microenvironment. [abstract]. In: Proceedings of the AACR-IASLC Joint Conference on Molecular Origins of Lung Cancer; 2014 Jan 6-9; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2014;20(2Suppl):Abstract nr A13.

Promoting effect of neutrophils on lung tumorigenesis is mediated by CXCR2 and neutrophil elastase

BACKGROUND

Tumor cells produce various cytokines and chemokines that attract leukocytes. Leukocytes can amplify parenchymal innate immune responses, and have been shown to contribute to tumor promotion. Neutrophils are among the first cells to arrive at sites of inflammation, and the increased number of tumor-associated neutrophils is linked to poorer outcome in patients with lung cancer.

RESULTS

We have previously shown that COPD-like airway inflammation promotes lung cancer in a K-ras mutant mouse model of lung cancer (CC-LR). This was associated with severe lung neutrophilic influx due to the increased level of neutrophil chemoattractant, KC. To further study the role of neutrophils in lung tumorigenesis, we depleted neutrophils in CC-LR mice using an anti-neutrophil antibody. This resulted in a significant reduction in lung tumor number. We further selectively inhibited the main receptor for neutrophil chemo-attractant KC, CXCR2. Similarly, this resulted in suppression of neutrophil recruitment into the lung of CC-LR mice followed by significant tumor reduction. Neutrophil elastase (NE) is a potent elastolytic enzyme produced by neutrophils at the site of inflammation. We crossed the CC-LR mice with NE knock-out mice, and found that lack of NE significantly inhibits lung cancer development. These were associated with significant reduction in tumor cell proliferation and angiogenesis.

CONCLUSION

We conclude that lung cancer promotion by inflammation is partly mediated by activation of the IL-8/CXCR2 pathway and subsequent recruitment of neutrophils and release of neutrophil elastase. This provides a baseline for future clinical trials using the IL-8/CXCR2 pathway or NE inhibitors in patients with lung cancer.