Aromatase in human lung carcinoma

Lung cancer is the leading cause of cancer mortality in both women and men worldwide but gender differences exist in their clinical and biological manifestations. In particular, among life time non-smoker, female are far more likely to develop lung carcinoma than male. Recent studies demonstrated that estrogens are synthesized in situ in both male and female lung cancers through aromatase, suggesting that sex steroid may contribute to the pathogenesis and development of lung carcinoma. In addition, human lung carcinomas have been recently demonstrated to be frequently associated with expression of estrogen receptors in both male and female patients and a lower expression of aromatase was reported to be associated with better prognosis. Preclinical studies further demonstrated that aromatase inhibitor (AI) suppressed the lung tumor growth both in vitro and in vivo. These findings all suggest a potential role of intratumoral aromatase in biological behavior of non-small cell lung cancer (NSCLC), the most common form of human lung malignancy. Therefore, AIs may become viable therapeutic options for disease management in NSCLC patients but further studies are definitely required to obtain a better understanding of the potential roles of intratumoral aromatase expression as a predictive biomarker for clinical outcome in these NSCLC patients.     

Estrogen receptor signaling pathways in human non-small cell lung cancer

Lung cancer is the most common cause of cancer mortality in male and female patients in the US. The etiology of non-small cell lung cancer (NSCLC) is not fully defined, but new data suggest that estrogens and growth factors promote tumor progression. In this work, we confirm that estrogen receptors (ER), both ERalpha and ERbeta, occur in significant proportions of archival NSCLC specimens from the clinic, with receptor expression in tumor cell nuclei and in extranuclear sites. Further, ERalpha in tumor nuclei was present in activated forms as assessed by detection of ER phosphorylation at serines-118 and -167, residues commonly modulated by growth factor receptor as well as steroid signaling. In experiments using small interfering RNA (siRNA) constructs, we find that suppressing expression of either ERalpha or ERbeta elicits a significant reduction in NSCLC cell proliferation in vitro. Estrogen signaling in NSCLC cells may also include steroid receptor coactivators (SRC), as SRC-3 and MNAR/PELP1 are both expressed in several lung cell lines, and both EGF and estradiol elicit serine phosphorylation of SRC-3 in vitro. EGFR and ER also cooperate in promoting early activation of p42/p44 MAP kinase in NSCLC cells. To assess new strategies to block NSCLC growth, we used Faslodex alone and with erlotinib, an EGFR kinase inhibitor. The drug tandem elicited enhanced blockade of the growth of NSCLC xenografts in vivo, and antitumor activity exceeded that of either agent given alone. The potential for use of antiestrogens alone and with growth factor receptor antagonists is now being pursued further in clinical trials.     

Progesterone receptor inhibits aromatase and inflammatory response pathways in breast cancer cells via ligand-dependent and ligand-independent mechanisms

Aromatase (product of CYP19 gene), the critical enzyme in estrogen biosynthesis, is up-regulated in 70% of all breast cancers and is highly correlated with cyclooxygenase 2 (COX-2), the rate-determining enzyme in prostanoid biosynthesis. Expression of COX-2 also is correlated with the oncogene HER-2/neu. The efficacy of current endocrine therapies for breast cancer is predicted only if the tumor contains significant amounts of estrogen receptor. Because the progesterone receptor (PR) is an estrogen-induced target gene, it has been suggested that its presence may serve as an indicator of estrogen receptor functional capacity and the differentiation state of the tumor. In the present study, we tested the hypothesis that PR serves a crucial protective role by antagonizing inflammatory response pathways in the breast. We observed that progesterone antagonized the stimulatory effects of cAMP and IL-1beta on aromatase, COX-2, and HER-2/neu expression in T47D breast cancer cells. These actions of progesterone were associated with increased expression of the nuclear factor-kappaB inhibitor, IkappaBalpha. In 28 breast cancer cell lines, IkappaBalpha expression was positively correlated with PR mRNA levels; overexpression of a phosphorylation-defective mutant of IkappaBalpha inhibited expression of aromatase, COX-2, and HER-2/neu. Moreover, in breast cancer cell lines cultured in the absence of progesterone, up-regulation of endogenous PR caused decreased expression of aromatase, COX-2, and HER-2/neu expression, whereas down-regulation of endogenous PR resulted in a marked induction of aromatase and HER-2/neu mRNA. Collectively, these findings suggest that PR plays an important antiinflammatory role in breast cancer cells via ligand-dependent and ligand-independent mechanisms.     

Relationship between aromatase activity and steroid receptor levels in ovarian tumors from postmenopausal women

Aromatase activity, as well as steroid receptors, exists in nonfunctional ovarian tumors. Steroid receptor status has been reported to be related to prognosis in ovarian cancer patients. We determined aromatase activity and progesterone receptor (PR) and estrogen receptor (ER) levels in 43 ovarian tumors obtained from postmenopausal women. Aromatase activity was detected in 35 tumors (81%), PR in 21 tumors (49%) and ER in 13 tumors (30%). Eighty-three percent (10/12) of mucinous cystadenoma tissues showed positive PR with high aromatase activity, while 93% (13/14) of malignant tumors showed negative PR and low aromatase activity. Aromatase activity was detected in 95% (20/21) of PR-positive tumors, being greater than in PR-negative tumors (P < 0.002). There was a positive correlation between aromatase activity and PR (r_s = 0.49, P < 0.001). However, there was no correlation between aromatase activity and ER. In 17 patients (43%), the serum estradiol level was higher than 30 pg/ml and there was a positive correlation among estradiol, estrone, androstenedione and testosterone. However, serum steroid levels were not correlated with aromatase activity, PR or ER. Aminoglutethimide inhibited aromatase activity of benign and malignant ovarian tumors, uterine myoma, choriocarcinoma cells and purified human placental P-450arom in a similar manner. These results suggest that aromatase activity is correlated with PR in ovarian tumors of postmenopausal women. In addition to steroid receptor status, aromatase activity may be a useful prognostic factor in ovarian cancers.     

非小细胞肺癌BRCA2的表达及其与ER、PR及c—erbB-2的相关性研究

目的在非小细胞肺癌中检测乳腺癌易感基因（BRCA2）的表达和ER、PR及c-erbB-2蛋白表达特点,探讨BRCA2的表达与ER、PR及c-erbB-2之间的相关性。方法免疫组织化学SP法检测了42例手术切除的非小细胞肺癌中ER、PR、c-erbB-2和BRCA2蛋白表达,根据各种临床病理因素分组进行BRCA2表达阳性率统计学分析。结果BRCA2蛋白表达阳性15例（35．7％）;BRCA2蛋白表达阳性率在大于或等于60岁与小于60岁两年龄组间、男女组间、鳞状细胞癌组与腺癌组间及其分化程度以及c-erbB-2表达阳性组与阴性组间比较有显著性差异（P〈0．01）;而在有无淋巴结转移组间BRCA2蛋白表达阳性率比较无显著性差异（P〉0．05）;ER、PR在所有非小细胞肺癌病例中均为阴性。结论非小细胞肺癌可见BRCA2和c-erbB-2的表达,其两者的表达具有相关性,可能存在协同作用。提示BRCA2和c-erbB-2可作为反映非小细胞肺癌恶性特征的一个检测指标。     

7,8-Dihydroxycoumarin exerts antitumor potential on DMBA-induced mammary carcinogenesis by inhibiting ERα, PR,EGFR, and IGF1R: involvement of MAPK1/2-JNK1/2-Akt pathway

Breast cancer (BC) is a persistent and impulsive metabolic disorder with the highest prevalence in women, worldwide. 7,12-Dimethylbenz(a)anthracene (DMBA) is a potent polyaromatic hydrocarbon (PAH)-based carcinogen producing mammary carcinomas in rats resembling the human hormone-dependent BC. 7,8-Dihydroxycoumarin (78DC) is a coumarin derivative that possesses diversified and favorable pharmacology profile to be considered in anticancer research against various malignancies. The present study was intended to investigate the antiproliferative and chemotherapeutic potentials of 78DC (20, 40, and 80 mg/kg BW) against DMBA (20 mg in olive oil)-induced mammary carcinoma Sprague-Dawley rats. We established the in silico approach for evaluation of the effect of 78DC on hormonal (estrogen receptor-α (ERα), progesterone receptor (PR)), growth factor receptors (EGFR and IGFR), 17β-hydroxysteroid dehydrogenase type 1 (17β-HD1), and aromatase. Effect of 78DC on estrogen synthesis, tumor growth, proliferation markers (Ki-67 and PCNA), cytokines (IL-10, IL-1β, IL-12), chemokine (MCP-1), and cellular expressions of ERα, PR, EGFR, IGF1R, p-MAPK1/2, p-JNK1/2, p-Akt, 17β-HD1, and aromatase was evaluated in mammary carcinoma bearing SD rats. DMBA induces large tumor burden and histological alterations in mammary gland with a subsequent increase in ERα, PR, EGFR, IGF1R, Ki-67, proliferating cell nuclear antigen (PCNA ), cytokines, and chemokine expressions. This was also correlated with the changes in rapid cell differentiation and proliferation. In contrast, 78DC treatment to the cancer-bearing animals abbreviated these changes and revealed to possess antitumorigenic and antiproliferative potentials. Further, a significant decrease in expressions of ERα, PR, EGFR, IGFR, p-MAPK1/2, p-JNK1/2, p-Akt, 17β-HD1, and aromatase signifies a reduction in estrogen sensitivity and secondary signaling pathways that may contribute to the prevention of tumor growth. The current findings revealed that 78DC potentially reduce cancer cell proliferation and reverted mammary cancer-induced changes in experimental animals in a dose-dependent manner.     

Cell density is a critical determinant of aromatase expression in adipose stromal cells

Obesity is associated with an increased risk of breast cancer among postmenopausal women. This is at least partly due to excessive estrogen production in adipose tissue of obese women. Aromatase, the key enzyme in estrogen biosynthesis, is an important target in endocrine therapy for estrogen receptor (ER)-positive postmenopausal breast cancer. In this study we show that high confluency of human adipose stromal cells (ASCs) cultured in vitro can significantly stimulate aromatase gene expression and reduce the expression of breast tumor suppressor BRCA1 and members of the NR4A orphan nuclear family. Furthermore, small interfering RNA (siRNA)-mediated knockdown of Nurr1, a member of the NR4A family, substantially increased aromatase expression. Lastly, we found that the cell density-triggered inducibility of aromatase expression varies in ASCs isolated from different disease-free individuals. Our finding highlights the impact of increased cell number on estrogen biosynthesis as in the case of excessive adiposity.     

Modulation of in situ estrogen synthesis by proline-, glutamic acid-, and leucine-rich protein-1: potential estrogen receptor autocrine signaling loop in breast cancer cells

In situ estrogen synthesis is implicated in tumor cell proliferation through autocrine or paracrine mechanisms especially in postmenopausal women. Several recent studies demonstrated activity of aromatase, an enzyme that plays a critical role in estrogen synthesis in breast tumors. Proline-, glutamic acid-, and leucine-rich protein-1 (PELP1/MNAR) is an estrogen receptor (ER) coregulator, and its expression is deregulated in breast tumors. In this study, we examined whether PELP1 promotes tumor growth by promoting local estrogen synthesis using breast cancer cells (MCF7) that stably overexpress PELP1. Immunohistochemistry revealed increased aromatase expression in MCF7-PELP1-induced xenograft tumors. Real-time PCR analysis showed enhanced activation of the aromatase promoter in MCF7-PELP1 clones compared with MCF7 cells. Using a tritiated-water release assay, we demonstrated that MCF7-PELP1 clones exhibit increased aromatase activity compared with control MCF-7 cells. PELP1 deregulation uniquely up-regulated aromatase expression via activation of aromatase promoter I.3/II, and growth factor signaling enhanced PELP1 activation of aromatase. PELP1-mediated induction of aromatase requires functional Src and phosphatidylinositol-3-kinase pathways. Mechanistic studies revealed that PELP1 interactions with ER-related receptor-alpha and proline-rich nuclear receptor coregulatory protein 2 lead to activation of aromatase. Immunohistochemistry analysis of breast tumor array showed increased expression of aromatase in ductal carcinoma in situ and node-positive tumors compared with no or weak expression in normal breast tissue. Fifty-four percent (n = 79) of PELP1-overexpressing tumors also overexpressed aromatase compared with 36% (n = 47) in PELP1 low-expressing tumors. Our results suggest that PELP1 regulation of aromatase represents a novel mechanism for in situ estrogen synthesis leading to tumor proliferation by autocrine loop and open a new avenue for ablating local aromatase activity in breast tumors.     

被动吸烟下调大鼠卵巢雌、孕激素及其受体的表达

目的利用Wistar大鼠烟雾吸入模型,观察被动吸烟对Wistar大鼠卵巢结构的影响,检测生殖激素水平,分析生殖内分泌的变化,为提倡生育期妇女避免被动吸烟提供新的理论依据。方法建立大鼠烟雾吸入模型。32只健康雌性Wistar大鼠,鼠龄(60±5)d,每只体重200～250g,随机分为空白对照组和实验组,每组16只。实验组吸烟3个月,对照组正常饲养。3个月后处死两组大鼠。酶联免疫吸附试验方法 (enzyme linkedimmunosorbent assay,ELISA)检测雌鼠血清中雌激素(estrogen,E2)、孕激素(progesterone,P4)的水平;常规石蜡切片,免疫组织化学SP法检测各组雌鼠卵巢雌激素受体(estrogen receptor,ER)、孕激素受体(progesterone receptor,PR)的表达情况。所得数据采用SPSS软件作统计学处理分析,比较各组间差异程度。结果①酶联免疫吸附试验结果 :吸烟3个月大鼠血清E2水平比空白对照组显著降低,其浓度值比较差异有显著性;吸烟3个月大鼠血清P4水平比空白对照组显著降低,其浓度值比较差异有显著性。②免疫组织化学结果 :ER主要表达在大鼠卵巢组织的各级生长卵泡的颗粒细胞的细胞核内,呈棕黄色颗粒状分布,卵泡膜细胞和间质细胞也有少量表达。吸烟3个月的大鼠卵巢组织中ER的表达显著低于空白对照组。PR主要表达在大鼠卵巢组织卵泡的颗粒细胞的细胞质和细胞核中,呈棕黄色颗粒状分布,吸烟3个月的大鼠卵巢组织中PR的表达显著低于空白对照组。结论①成功的建立了大鼠被动吸烟模型。②被动吸烟可使大鼠血清中E2及P4水平明显降低,使大鼠卵巢中ER及PR的表达减少,提示被动吸烟可破坏卵巢的功能,引起生殖内分泌失调。     

Estrogen and growth factor receptor interactions in human breast and non-small cell lung cancer cells

Extranuclear estrogen receptors may mediate rapid effects of estradiol that communicate with nuclear receptors and contribute to proliferation of human cancers bearing these signaling proteins. To assess these growth-promoting pathways, we undertook controlled homogenization and fractionation of NIH-H23 non-small cell lung cancer cells. As many breast tumors, NIH-H23 cells express estrogen receptors (ER), with the bulk of specific estradiol binding in nuclear fractions. However, as in breast cells, a significant portion of specific, high-affinity estradiol-17beta binding-sites are also enriched in plasma membranes of lung tumor cells. These estrogen binding-sites co-purify with plasma membrane-marker enzymes and are not significantly contaminated by cytosol or nuclei. On further purification of membrane caveolae from lung tumor cells, proteins recognized by monoclonal antibodies to nuclear ER-alpha and to ER-beta were identified in close association with EGF receptor in caveolae. In parallel studies, ER-alpha and ER-beta are also detected in nuclear and extranuclear sites in archival human breast and lung tumor samples and are noted to occur in clusters at the cell membrane by using confocal microscopy to visualize fluorescent-labeled monoclonal antibodies to ER-alpha. Data on site-directed mutagenesis of cysteine-447 in ER-alpha suggest that association of ER forms with membrane sites may depend on acylation of cysteine by palmitate. Estrogen-induced growth of MCF-7 breast cancer and NIH-H23 lung cancer cells in vitro correlated closely with acute hormonal activation of mitogen-activated protein kinase signaling and was significantly reduced by treatment with Faslodex, a pure anti-estrogen. Further, combination of Faslodex with selected growth factor receptor inhibitors elicited a more pronounced inhibiton of tumor cell growth. Thus, extranuclear forms of ER play a role in promoting downstream signaling for hormone-mediated proliferation and survival of breast, as well as lung, cancers and offer a new target for anti-tumor therapy.     

Agreement of self-reported hormone receptor status with cancer registry data in young breast cancer patients

BackgroundThough breast cancer subtype is a key determinant of treatment choice and prognosis, few studies have assessed breast cancer patients’ knowledge of estrogen and progesterone receptor (ER/PR) status.MethodsWomen diagnosed with invasive breast cancer at age 18–64 years in 2007 were recruited from the Pennsylvania Cancer Registry, and mailed a questionnaire that asked respondents to identify their ER/PR status. There were 2191 respondents included in the analysis. Agreement between self-report and cancer registry ER/PR status was assessed using kappa statistic. Logistic regression was used to assess the association of demographic, socioeconomic, and tumor factors with inaccurate self-report of ER/PR status.ResultsFifty-nine percent of respondents reported ER/PR positive status, 15% reported ER/PR negative status, 17% responded ‘don’t know’, and 9% did not respond. Overall, there was 69% agreement between self-report and cancer registry data, and fair agreement as measured by kappa (0.36). After excluding women who did not know or did not report their ER/PR status, there was 93% agreement, and substantial agreement as measured by kappa (0.76). Women who were older, non-white, less educated, lower income, and had ER/PR negative disease were significantly more likely to inaccurately report their ER/PR status.ConclusionsThough a significant proportion of women do not know their hormone receptor status, women who reported their ER/PR status were accurate. Our results suggest room for improvement in patient knowledge of tumor subtypes, but also that self-reported ER/PR status may be a useful surrogate when medical record or cancer registry data is unavailable.     

Aromatase in the normal breast and breast cancer

Adipose tissue and muscle constitute the larger proportion of body mass, and therefore aromatization in these tissues is the major source of circulating estrogens in postmenopausal women. Although plasma estrogen concentrations are very low, levels in breast cancers from postmenopausal patients are reported to be 10-fold higher than in plasma and normal tissue. Whereas studies on aromatase activity in the tumor suggest that estrogen may be produced locally, the significance of this contribution has been questioned. Using immunocytochemistry (ICC) to an anti-aromatase antibody, a relatively strong immunoreaction was detected in tumor epithelial cells as well as in the terminal ductal lobular units (TDLUs) of the normal breast. Aromatase expression was detected in the cytoplasm of tumor epithelial cells and the surrounding stromal cells of over 50% of tumors in a series of 19 breast cancers. In situ hybridization (ISH) to aromatase mRNA confirmed the immunocytochemical result that the epithelial cells are the primary site of estrogen synthesis in the breast and breast cancers. In the 10 tumors which showed immunoreaction to aromatase, the average aromatase activity measured in cryosections was 286.5 ± 18.6 fmol estrogen/mg protein/h (SE), whereas in nine tumors with weak aromatase immunoreaction, the enzyme activity was 154.7 ± 19.3 fmol estrogen/mg protein/h (P < 0.05) (SE). The functional significance of tumor aromatase and locally produced estrogens on the growth of tumors was suggested by the correlation between aromatase activity and proliferating cell nuclear antigen (PCNA), a marker of cell proliferation (P < 0.005). Although intratumoral aromatase activity did not correlate with steroid receptors significantly, there was a trend for estrogen receptor (ER)-positive tumors to express aromatase. In addition, proliferation ([³H]-thymidine incorporation into DNA) during histoculture, was increased by both estradiol and testosterone in tumors with high aromatase activity. Our results suggest that some tumors synthesize sufficient estrogen to stimulate their proliferation. It may thus be important to inhibit tumor aromatase as well as to reduce circulating levels of estrogen for effective breast cancer treatment.     

Docosahexaenoic acid induces proteasome-dependent degradation of estrogen receptor α and inhibits the downstream signaling target in MCF-7 breast cancer cells

About two thirds of breast cancers in women are hormone-dependent and require estrogen for growth, its effects being mainly mediated through estrogen receptor α (ERα). Docosahexaenoic acid (DHA, 22:6n-3) and arachidonic acid (AA, 20:4n-6) have opposite effects on carcinogenesis, with DHA suppressing and AA promoting tumor growth both in vitro and in vivo. However, the mechanism is not clear. Here, we examined whether the effect is mediated through changes in ERα distribution. MCF-7 cells, an ERα-positive human breast cancer cell line, was cultured in estrogen-free medium containing 0, 10 or 60 μM DHA or AA, then were stimulated with estradiol. DHA supplementation resulted in down-regulation of ERα expression (particularly in the extranuclear fraction), a reduction in phosphorylated MAPK, a decrease in cyclin D1 levels and an inhibition in cell viability. In contrast, AA had no such effects. The DHA-induced decrease in ERα expression resulted from proteasome-dependent degradation and not from decreased ERα mRNA expression. We propose that breast cancer cell proliferation is inhibited by DHA through proteasome-dependent degradation of ERα, reduced cyclin D1 expression and inhibition of MAPK signaling.     

Estrogen Receptor 1 Gene Expression and Its Combination with Estrogen Receptor 2 or Aromatase Expression Predicts Survival in Non-Small Cell Lung Cancer

The biological roles of estrogen receptor 1 (ERS1), estrogen receptor 2 (ERS2), and aromatase (CYP19A1) genes in the development of non-small cell lung cancer (NSCLC) is unclear, as is the use of their expression as a prognostic factor. The aim of this study was to investigate the prognostic value of estrogen receptors and aromatase mRNA expression, along with aromatase protein concentration, in resected NSCLC patients. Tumor and non-tumor lung tissue samples were analyzed for the mRNA expression of ERS1, ERS2 and CYP19A1 by RT-PCR. Aromatase concentration was measured with an ELISA. A total of 96 patients were included. ERS1 expression was significantly higher in non-tumor tissue than in tumor samples. Two gene expression categories were created for each gene (and protein): high and low. ERS1 high category showed increased overall survival (OS) when compared to the low expression category. Aromatase protein concentration was significantly higher in tumor samples. Higher ERS1 expression in tumor tissues was related to longer overall survival. The analysis of gene expression combinations provides evidence for longer OS when both ERS1 and ERS2 are highly expressed. ESR1, alone or in combination with ERS2 or CYP19A1, is the most determining prognostic factor within the analyzed 3 genes. It seems that ERS1 can play a role in NSCLC prognosis, alone or in combination with other genes such as ERS2 or Cyp19a1. ERS2 in combination with aromatase concentration could have a similar function.     

Estrogen receptor β signaling regulates the progression of Chinese non-small cell lung cancer

Prospective studies have found that the risk of non-small cell lung cancer (NSCLC) has close relationship with estrogen. The effects of estrogens are mediated via two estrogen receptor (ER) isoforms, that is, ER alpha (ERα) and ER beta (ERβ). ERα in NSCLC has been evaluated mostly by immunohistochemistry. However, our previous study showed that ERβ was also highly expressed in Chinese NSCLC. But the roles of ERβ in Chinese NSCLC have not been clarified as yet. So in the present study, two Chinese lung adenocarcinoma cell lines, SPC-A1 and LTEP-a2, were used and the role of ERβ in lung tumorigenesis was focused to be investigated by in vitro and in vivo experiments. The results showed that over-expressed ERβ can promote the development of NSCLC, while siRNAs targeting ERβ gene can inhibit growth of NSCLC cells and induce apoptosis of these cells via mitochondrial depolarization and caspase-3 activation. These results indicated that ERβ plays an important role in development of Chinese NSCLC. This suggests that ERβ deactivation or down-regulation may possess potential therapeutic utility for the treatment of lung cancer.     

Low expression of ITIH5 in adenocarcinoma of the lung is associated with unfavorable patients' outcome

Inter-α-trypsin inhibitor heavy chain 5 (ITIH5) is supposed to be involved in extracellular matrix stability and thus may play a key role in the inhibition of tumor progression. The current study is the first to analyze in depth ITIH5 expression and DNA methylation, as well as its potential clinical impact in non-small-cell lung carcinoma (NSCLC). We examined ITIH5 mRNA expression in tumor and adjacent normal lung tissue specimens of NSCLC patients. In addition, methylation frequency of the ITIH5 promoter was investigated using methylation-specific PCR and pyrosequencing. Significance of our data was validated by independent data sets from The Cancer Genome Atlas and the Kaplan-Meier Plotter platform. Furthermore, ITIH5 protein expression was evaluated by immunohistochemistry utilizing a tissue microarray with 385 distinct lung tissue samples. Based on our tissue collections, ITIH5 mRNA expression was significantly decreased in NSCLC compared to normal lung tissue in line with an increased methylation frequency in lung cancer tissue. Independent TCGA data confirmed significant expression loss of ITIH5 in lung cancer concordant with ITIH5 promoter hypermethylation in NSCLC. Of interest, low ITIH5 mRNA expression was particularly found in the magnoid and squamoid ADC expression subtype, concordant with an unfavorable patients'' outcome in squamoid as well as tobacco smoking ADC patients. In conclusion, ITIH5 may be a novel putative tumor suppressor gene in NSCLC with a potential molecular significance in the squamoid ADC subtype and further clinical impact for risk stratification of adenocarcinoma patients. In addition, ITIH5 may serve as a novel biomarker for prognosis of tobacco smoking ADC patients.