Bronchogenic cysts in rare sites (retroperitoneum, skin, spinal cord and pericardial cavity): A case series and characterization of epithelial phenotypes.

Bronchogenic cysts are congenital malformations of the bronchial tree, detected as a cystic and/or mass lesion in the thoracic cavity. Although it occurs in distant locations, such as skin and retroperitoneum, to the best of our knowledge, little is known about the components and phenotypes of the epithelium that line a bronchogenic cyst in rare sites. The present study reviewed 34 bronchogenic cysts that were surgically resected at Osaka Medical and Pharmaceutical University Hospital (Osaka, Japan) from January 1998 to December 2020. Bronchogenic cysts in rare sites were detected and diagnosis was confirmed based on the presence of pseudostratified, ciliated and/or columnar epithelium together with at least one of the following: Cartilage, smooth muscle or seromucous glands. The phenotypes of epithelium lining the cyst were characterized using immunohistochemical analysis. A total of six bronchogenic cysts in rare sites (two cases each in the retroperitoneum and skin and one case each in the cervical spinal cord and pericardial cavity) met the criteria for confirmation of the diagnoses. The epithelium lining the cyst stained positive for cytokeratin CK7 and thyroid transcription factor 1 (a marker expressed in thyroid follicles and bronchial epithelium) and negative for CK20, indicating that the phenotypes were similar to those of the respiratory epithelium. The present study demonstrated that a bronchogenic cyst can occur in rare sites, such as the retroperitoneum, skin, spinal cord and pericardial cavity, suggesting that it should be considered as a differential diagnosis before surgical approach to implement relevant management modalities such as follow-up, simple or radical resection.

Inhibition of the NOTCH and mTOR pathways by nelfinavir as a novel treatment for T cell acute lymphoblastic leukemia.

T cell acute lymphoblastic leukemia (T­ALL), a neoplasm derived from T cell lineage­committed lymphoblasts, is characterized by genetic alterations that result in activation of oncogenic transcription factors and the NOTCH1 pathway activation. The NOTCH is a transmembrane receptor protein activated by γ­secretase. γ­secretase inhibitors (GSIs) are a NOTCH­targeted therapy for T­ALL. However, their clinical application has not been successful due to adverse events (primarily gastrointestinal toxicity), limited efficacy, and drug resistance caused by several mechanisms, including activation of the AKT/mTOR pathway. Nelfinavir is an human immunodeficiency virus 1 aspartic protease inhibitor and has been repurposed as an anticancer drug. It acts by inducing endoplasmic reticulum (ER) stress and inhibiting the AKT/mTOR pathway. Thus, it was hypothesized that nelfinavir might inhibit the NOTCH pathway via γ­secretase inhibition and blockade of aspartic protease presenilin, which would make nelfinavir effective against NOTCH­associated T­ALL. The present study assessed the efficacy of nelfinavir against T­ALL cells and investigated mechanisms of action in vitro and in preclinical treatment studies using a SCL­LMO1 transgenic mouse model. Nelfinavir blocks presenilin 1 processing and inhibits γ­secretase activity as well as the NOTCH1 pathway, thus suppressing T­ALL cell viability. Additionally, microarray analysis of nelfinavir­treated T­ALL cells showed that nelfinavir upregulated mRNA levels of CHAC1 (glutathione­specific γ­glutamylcyclotransferase 1, a negative regulator of NOTCH) and sestrin 2 (SESN2; a negative regulator of mTOR). As both factors are upregulated by ER stress, this confirmed that nelfinavir induced ER stress in T­ALL cells. Moreover, nelfinavir suppressed NOTCH1 mRNA expression in microarray analyses. These findings suggest that nelfinavir inhibited the NOTCH1 pathway by downregulating NOTCH1 mRNA expression, upregulating CHAC1 and suppressing γ­secretase via presenilin 1 inhibition and the mTOR pathway by upregulating SESN2 via ER stress induction. Further, nelfinavir exhibited therapeutic efficacy against T­ALL in an SCL­LMO1 transgenic mouse model. Collectively, these findings highlight the potential of nelfinavir as a novel therapeutic candidate for treatment of patients with T­ALL.

A case of renomedullary interstitial cell tumor: Radiologic-pathologic correlation.

Renomedullary interstitial cell tumor (RMICT), referred to as a medullary fibroma, is almost always asymptomatic and incidentally identified either at autopsy or upon resection of the kidney for other reasons. Although a few cases of RMICTs that are large in size and clinically symptomatic have been reported, there are few reports of RMICTs contrasting imaging findings with pathological findings. In this report, we describe a relatively large RMICT case of 3 cm in size, focusing on the radiologic-pathologic correlation.

A glucocorticoid-receptor agonist ameliorates bleomycin-induced alveolar simplification in newborn rats.

BACKGROUND: Glucocorticoids (GCs) are highly effective yet problematic agents against bronchopulmonary dysplasia (BPD). The dimeric trans-activation of GCs induces unfavorable effects, while monomeric trans-repression suppresses inflammation-related genes. Recently, non-steroidal-selective glucocorticoid-receptor agonists and modulators (SEGRAMs) with only the trans-repressive action have been designed. METHODS: Using a bleomycin (Bleo)-induced alveolar simplification newborn rat model (recapitulating arrested alveolarization during BPD), we evaluated the therapeutic effects of compound-A (CpdA), a SEGRAM. Sprague-Dawley rats were administered Bleo from postnatal day (PD) 0 to 10 and treated with dexamethasone (Dex) or CpdA from PD 0 to 13. The morphological changes and mRNA expression of inflammatory mediators, including interleukin (IL)-1ß, C-X-C motif chemokine ligand 1 (CXCL1), and C-C motif chemokine 2 (CCL2) were investigated. RESULTS: Similar to the effects of Dex, CpdA exerted protective effects on morphological derangements and inhibited macrophage infiltration and production of pro-inflammatory mediators in Bleo-treated animals. The effects of CpdA were probably mediated by GC receptor (GR)-dependent trans-repression, because unlike the Dex-treated group, anti-inflammatory genes specifically induced by GR-dependent trans-activation (such as "glucocorticoid-induced leucine zipper, GILZ") were not upregulated. CONCLUSIONS: CpdA improved lung inflammation, inhibited the arrest of alveolar maturation, and restored histological and biochemical changes in a Bleo-induced alveolar simplification model. IMPACT: SEGRAMs have attracted widespread attention because they are expected to not exhibit unfavorable effects of GCs. Compound A, one of the SEGRAMs, improved lung morphometric changes and decreased lung inflammation in a bleomycin-induced arrested alveolarization, a newborn rat model representing one of the main features of BPD pathology. Compound A did not elicit bleomycin-induced poor weight gain, in contrast to dexamethasone treatment. SEGRAMs, including compound A, may be promising candidates for the therapy of BPD with less adverse effects compared with GCs.

Breast neuroendocrine tumor arising in the axilla of a man: a case report.

BACKGROUND: Accessory breast carcinomas of the axilla of males are rare, and primary breast neuroendocrine tumors (BNETs) are rare as well. We present a case of a BNET arising in the axilla of a man. CASE PRESENTATION: A 64-year-old Japanese man presented with a hard 15-mm mass in the axilla and axillary lymph node swelling. Histopathological examination of the incisional biopsy specimen revealed a neuroendocrine carcinoma. Therefore, wide radical excision of the axillary tumor and axillary lymph node dissection were performed. Hematoxylin and eosin staining showed that the solid tumor was mainly located in the subcutaneous adipose tissues and appeared to invade the skin. The tumor phenotypes were positive for CAM 5.2, synaptophysin, estrogen receptor, progesterone receptor, and GATA-binding protein 3; they were negative for human epidermal growth receptor 2. The neuroendocrine component comprised more than 90% of the tumor, and the Ki-67 index was 21%. These results indicated that the tumor was a BNET. This patient underwent adjuvant chemotherapy, endocrine therapy, and radiotherapy. CONCLUSIONS: BNET cases in males are rare. The clinical and histological criteria as well as treatment for these rare cases are discussed.

Conjunctival epithelial hyperplasia in a patient with a nodular lesion in the palpebral conjunctiva: A case report.

The conjunctiva is a thin and delicate mucous membrane lining the inner eyelid and the anterior surface of the eyeball. Although hyperplastic changes can occur due to nonspecific chronic inflammation, 'conjunctival epithelial hyperplasia' has not been sufficiently established as a pathological entity. Additionally, the immunohistochemical (IHC) features of both the intact conjunctiva epithelium and conjunctival epithelial hyperplasia have not been sufficiently evaluated. The present report describes the case of an 86-year-old man who consulted with an ophthalmologist for a 6-month-old nodular lesion on his left eye. Located in the medial aspect of the left lower palpebral conjunctiva, the lesion was slightly erythematous and smooth. An excisional biopsy of the lesion was performed to obtain a pathological diagnosis. The hematoxylin and eosin sections revealed a thickened conjunctival epithelium composed of hyperplastic cuboidal epithelial cells and goblet cells, indicating conjunctival epithelial hyperplasia. Atypia, increased mitosis and a papillomatous architecture, indicative of neoplastic changes, were not observed. This resulted in conjunctival squamous intraepithelial neoplasia and squamous cell papilloma being ruled out. IHC analysis was performed to further characterize the lesion as well as the intact conjunctival epithelium. The thick conjunctival epithelium was composed of epithelial cells that stained positive for cytokeratin [AE1/AE3 (intensity: +), CK5/6 (intensity: ++), and CK7 (intensity: +)] and p63-positive basal cells (intensity: +) whose presence in the conjunctiva has received insufficient recognition. Moreover, squamous metaplasia was found in a segment of the thick conjunctiva, which exhibited IHC features similar to those of hyperplasia. CK5/6 was positive, indicating endogenous squamous differentiation of the conjunctival epithelial hyperplasia. These findings led to the diagnosis of conjunctival epithelial hyperplasia as a pathological entity. Further collection and analysis of several cases of conjunctival epithelial hyperplasia may lead the development of preventative methods and drug treatments for this lesion, and additional prognostic data, such as the recurrence rate.

Nelfinavir Inhibits the Growth of Small-cell Lung Cancer Cells and Patient-derived Xenograft Tumors.

BACKGROUND/AIM: Small-cell lung cancer (SCLC) is aggressive and confers poor prognosis. Although SCLC shows more response to chemotherapy than other types of lung cancer, it is difficult to cure because of its frequent recurrence. New drugs and molecular targets need to be identified. MATERIALS AND METHODS: We investigated the effect of nelfinavir, an HIV protease inhibitor, on SCLC cells and in preclinical treatment studies using SCLC patient-derived xenograft (PDX) mouse models. RESULTS: Nelfinavir inhibited SCLC cell proliferation and induced cell death in vitro, which was caused by induction of the unfolded protein response (UPR), inhibition of mammalian/mechanistic target of rapamycin (mTOR) activation, and reduction in the expression of SCLC-related molecules such as achaete-scute homolog 1 (ASCL1). In vivo, nelfinavir inhibited the growth of SCLC PDX tumors, which correlated with the induction of UPR and reduced expression of ASCL1. CONCLUSION: Nelfinavir is highly effective in SCLC in vitro and in vivo, suggesting possible incorporation of nelfinavir into clinical trials for patients with SCLC.

Combining Nelfinavir With Chloroquine Inhibits In Vivo Growth of Human Lung Cancer Xenograft Tumors.

BACKGROUND/AIM: Nelfinavir is a human immunodeficiency virus protease inhibitor that is currently being repositioned as an anticancer drug. Chloroquine, an anti-malarial lysosomotropic drug, inhibits autophagy. It has been reported that the combination of nelfinavir and chloroquine significantly enhances endoplasmic reticulum (ER) stress and induces selective cell death in multiple cell line models (in vitro). MATERIALS AND METHODS: We assessed the effects of the combination of these drugs on human NSCLC cell lines in vitro using cell proliferation assay and performed preclinical treatment studies using cell line-derived xenograft mouse models in vivo. RESULTS: In vitro, this combination enhanced inhibition of NSCLC cell proliferation with increased proteotoxicity, including ER stress, and apoptosis. In vivo, the growth of human NSCLC xenograft tumors was inhibited, which correlated with increased apoptosis and induction of ER stress as well as NSCLC growth in vitro. CONCLUSION: Our findings suggest that the induction of proteotoxicity provides a promising new target for developing anticancer drugs.

A phase I/II study of pemetrexed with sirolimus in advanced, previously treated non-small cell lung cancer.

BACKGROUND: Single-agent pemetrexed is a treatment for recurrent non-squamous non-small cell lung cancer (NSCLC) that provides limited benefit. Preclinical studies showed promising synergistic effects when the mammalian target of rapamycin (mTOR) inhibitor sirolimus was added to pemetrexed. METHODS: This was a single-institution phase I/II study of pemetrexed in combination with sirolimus. The primary endpoint for the phase I was to determine the maximum tolerated dose (MTD) and safety of the combination. The primary endpoint for the phase II portion was to determine the overall response rate at the MTD. Key eligibility criteria included recurrent, metastatic NSCLC, ECOG performance status of 0-2, and adequate organ function. Sirolimus was administered orally daily after an initial loading dose, and pemetrexed was given intravenously on day 1 of every 21-day cycle. RESULTS: Forty-two patients with recurrent, metastatic NSCLC were enrolled, 22 in phase I and 20 in phase II. The MTD was pemetrexed 500 mg/m2 every 3 weeks, and sirolimus 10 mg on day 1, and 3 mg daily thereafter. Treatment-related adverse events (AEs) occurred in 38 (90.5%) patients. The most common grade 3-4 treatment-related AEs were lymphopenia (31%) and hypophosphatemia (19%). Two treatment-related deaths occurred due to febrile neutropenia and infection, respectively. Among 27 total patients treated at the MTD, 6 (22.2%) had a partial response (PR), 12 (44.4%) had stable disease (SD) and 5 (18.5%) had progressive disease. Median progression-free survival (PFS) was 18.4 weeks (95% CI: 7.0-29.4). CONCLUSIONS: The combination of pemetrexed and sirolimus is active in heavily-pretreated NSCLC (ClinicalTrials.gov Identifier: NCT00923273).

Rapamycin sensitizes cancer cells to growth inhibition by the PARP inhibitor olaparib.

Poly (ADP-ribose) polymerase inhibitors (PARPi) have been developed and tested in a context of combining it with double-stranded (ds) DNA repair defects or inhibitors, as PARP inhibitor impairs single-stranded (ss) DNA break repair, resulting in the activation of the dsDNA break repair machinery. Rapamycin has been widely prescribed for more than a decade and recent studies have revealed that it may inhibit dsDNA break repair. The combination of the PARP inhibitor olaparib and rapamycin synergistically inhibited cell proliferation in non-small cell lung cancer (NSCLC) cells, and even in triple negative breast cancer (TNBC) cells with BRCA1 mutations. Rad51, which forms a polymer on ssDNA upon dsDNA breaks, plays an essential role in homologous recombination. Olaparib induced Rad51 focus formation, while rapamycin successfully inhibited it both in vivo and in vitro, suggesting that this combination worked through the blocking of both ssDNA break repair and dsDNA break repair; hence the cells cannot go through the G2/M checkpoint. The protein level of PARP was a predictive marker for both PAR activity and Rad51 focus formation in this combination. Collectively, these data suggest that this combination could have therapeutic potential in the treatment of cancer with high PARP expression, or in combination with cytotoxic chemotherapy or radiotherapy.

Control of PD-L1 Expression by Oncogenic Activation of the AKT-mTOR Pathway in Non-Small Cell Lung Cancer.

Alterations in EGFR, KRAS, and ALK are oncogenic drivers in lung cancer, but how oncogenic signaling influences immunity in the tumor microenvironment is just beginning to be understood. Immunosuppression likely contributes to lung cancer, because drugs that inhibit immune checkpoints like PD-1 and PD-L1 have clinical benefit. Here, we show that activation of the AKT-mTOR pathway tightly regulates PD-L1 expression in vitro and in vivo. Both oncogenic and IFNγ-mediated induction of PD-L1 was dependent on mTOR. In human lung adenocarcinomas and squamous cell carcinomas, membranous expression of PD-L1 was significantly associated with mTOR activation. These data suggest that oncogenic activation of the AKT-mTOR pathway promotes immune escape by driving expression of PD-L1, which was confirmed in syngeneic and genetically engineered mouse models of lung cancer where an mTOR inhibitor combined with a PD-1 antibody decreased tumor growth, increased tumor-infiltrating T cells, and decreased regulatory T cells.

Epidermal growth factor receptor as a novel molecular target for aggressive papillary tumors in the middle ear and temporal bone.

Adenomatous tumors in the middle ear and temporal bone are rare but highly morbid because they are difficult to detect prior to the development of audiovestibular dysfunction. Complete resection is often disfiguring and difficult because of location and the late stage at diagnosis, so identification of molecular targets and effective therapies is needed. Here, we describe a new mouse model of aggressive papillary ear tumor that was serendipitously discovered during the generation of a mouse model for mutant EGFR-driven lung cancer. Although these mice did not develop lung tumors, 43% developed head tilt and circling behavior. Magnetic resonance imaging (MRI) scans showed bilateral ear tumors located in the tympanic cavity. These tumors expressed mutant EGFR as well as active downstream targets such as Akt, mTOR and ERK1/2. EGFR-directed therapies were highly effective in eradicating the tumors and correcting the vestibular defects, suggesting these tumors are addicted to EGFR. EGFR activation was also observed in human ear neoplasms, which provides clinical relevance for this mouse model and rationale to test EGFR-targeted therapies in these rare neoplasms.

Impact of HIV on lung tumorigenesis in an animal model.

Many HIV patients on antiretroviral therapy have controlled viremia and restored (albeit partially) immunity. Yet, they have high rates of lung cancer, even after controlling for smoking. We tested the hypothesis that HIV proteins accelerate development/progression of lung cancer in an immunocompetent HIV transgenic mouse model. The expression of HIV proteins did not enhance lung tumorigenesis caused by two different tobacco carcinogens, suggesting that incompletely restored immunity and/or inflammation, which persist(s) in most HIV patients despite controlled viremia, underlie(s) excess risk of lung cancer. Adjuvant therapies that restore immunity and lower inflammation may decrease lung cancer mortality in HIV patients.

A phase I trial of the HIV protease inhibitor nelfinavir in adults with solid tumors.

Nelfinavir is an HIV protease inhibitor being repurposed as an anti-cancer agent in preclinical models and in small oncology trials, yet the MTD of nelfinavir has not been determined. Therefore, we conducted a Phase Ia study to establish the maximum tolerated dose (MTD) and dose limiting toxicities (DLT) of nelfinavir in subjects with advanced solid tumors. Adults with refractory cancers were given oral nelfinavir twice daily with pharmacokinetic and pharmacodynamic analyses. Twenty-eight subjects were enrolled. Nelfinavir was generally well tolerated. Common adverse events included diarrhea, anemia, and lymphopenia, which were mostly mild. The DLT was rapid-onset neutropenia that was reversible. The MTD was established at 3125 mg twice daily. In an expansion cohort at the MTD, one of 11 (9%) evaluable subjects had a confirmed partial response. This, plus two minor responses, occurred in subjects with neuroendocrine tumors of the midgut or pancreatic origin. Thirty-six percent of subjects had stable disease for more than 6 months. In peripheral blood mononuclear cells, Nelfinavir inhibited AKT and induced markers of ER stress. In summary, nelfinavir is well tolerated in cancer patients at doses 2.5 times the FDA-approved dose for HIV management and showed preliminary activity in tumors of neuroendocrine origin.

Rapamycin prevents the development and progression of mutant epidermal growth factor receptor lung tumors with the acquired resistance mutation T790M.

Lung cancer in never-smokers is an important disease often characterized by mutations in epidermal growth factor receptor (EGFR), yet risk reduction measures and effective chemopreventive strategies have not been established. We identify mammalian target of rapamycin (mTOR) as potentially valuable target for EGFR mutant lung cancer. mTOR is activated in human lung cancers with EGFR mutations, and this increases with acquisition of T790M mutation. In a mouse model of EGFR mutant lung cancer, mTOR activation is an early event. As a single agent, the mTOR inhibitor rapamycin prevents tumor development, prolongs overall survival, and improves outcomes after treatment with an irreversible EGFR tyrosine kinase inhibitor (TKI). These studies support clinical testing of mTOR inhibitors in order to prevent the development and progression of EGFR mutant lung cancers.

SOX2 expression is an early event in a murine model of EGFR mutant lung cancer and promotes proliferation of a subset of EGFR mutant lung adenocarcinoma cell lines.

OBJECTIVES: Primary and acquired resistance to EGFR TKIs in EGFR mutant lung cancer occurs primarily through secondary mutations in EGFR or Met amplification. Drug resistance can also be mediated by expression of pluripotency transcription factors, such as OCT4, SOX2 and NANOG that decrease terminal differentiation. In this study, we investigated the expression and role of SOX2 in model systems of EGFR mutant tumors. MATERIALS AND METHODS: Immunoblotting or immunohistochemistry was used to assess expression of pluripotency transcription factors in lungs of transgenic mice or in human NSCLC cell lines. Expression of SOX2 was reduced by shRNA knockdown, and response to erlotinib and cellular proliferation were assessed. RESULTS AND CONCLUSION: Induction of mutant EGFR in transgenic CCSP-rtTA/TetO-EGFR(L858R/T790M) mice correlated with increased OCT4 and SOX2 expression in lung tissue prior to tumor development. Established lung tumors retained SOX2 expression. To assess a role for SOX2 in tumorigenesis, a panel of NSCLC cell lines with activating EGFR mutations was assessed for SOX2 expression. Two of six cell lines with mutant EGFR showed detectable SOX2 levels, suggesting SOX2 expression did not correlate with EGFR mutation status. To assess the role of SOX2 in these cell lines, HCC827 and H1975 cells were infected with lentivirus containing SOX2 shRNA. Knockdown of SOX2 decreased proliferation in both cell lines and increased sensitivity to erlotinib in HCC827 cells. Because constitutive activation of the PI3K/Akt pathway is associated with EGFR TKI resistance, cells were treated with PI3K/AKT inhibitors and expression of SOX2 was examined. PI3K/Akt inhibitors decreased SOX2 expression in a time-dependent manner. These data suggest targeting SOX2 may provide therapeutic benefit in the subset of EGFR-mutant tumors with high constitutive levels of SOX2, and that until more direct means of inhibiting SOX2 are developed, PI3K/Akt inhibitors might be useful to inhibit SOX2 in EGFR TKI resistant tumors.

Rapamycin downregulates thymidylate synthase and potentiates the activity of pemetrexed in non-small cell lung cancer.

Non-small cell lung cancer (NSCLC) accounts for 80-85% of lung cancer cases, and almost half of newly diagnosed patients have metastatic disease. Pemetrexed is a widely used drug for NSCLC and inhibits several folate-dependent enzymes including thymidylate synthase (TS). Increased expression of TS confers resistance to pemetrexed in vitro and predicts poor response to pemetrexed. Rapamycin is an mTOR inhibitor and suppresses cap-dependent synthesis of specific mRNA species. Here, we show that the combination of rapamycin and pemetrexed synergistically inhibits proliferation of NSCLC cells. Although pemetrexed as a single agent induced TS, pretreatment with rapamycin suppressed pemetrexed-induced TS expression. In vivo, the combination of rapamycin and pemetrexed inhibited growth of NSCLC xenografts, which correlated with decreased mTOR activity and suppression of pemetrexed-induced TS expression. The ability of rapamycin to enhance the efficacy of pemetrexed and prevent TS expression has implications for the design of Phase I and/or Phase II NSCLC clinical trials with mTOR inhibitors in combination with pemetrexed.

Metformin prevents tobacco carcinogen--induced lung tumorigenesis.

Activation of the mammalian target of rapamycin (mTOR) pathway is an important and early event in tobacco carcinogen-induced lung tumorigenesis, and therapies that target mTOR could be effective in the prevention or treatment of lung cancer. The biguanide metformin, which is widely prescribed for the treatment of type II diabetes, might be a good candidate for lung cancer chemoprevention because it activates AMP-activated protein kinase (AMPK), which can inhibit the mTOR pathway. To test this, A/J mice were treated with oral metformin after exposure to the tobacco carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). Metformin reduced lung tumor burden by up to 53% at steady-state plasma concentrations that are achievable in humans. mTOR was inhibited in lung tumors but only modestly. To test whether intraperitoneal administration of metformin might improve mTOR inhibition, we injected mice and assessed biomarkers in liver and lung tissues. Plasma levels of metformin were significantly higher after injection than oral administration. In liver tissue, metformin activated AMPK and inhibited mTOR. In lung tissue, metformin did not activate AMPK but inhibited phosphorylation of insulin-like growth factor-I receptor/insulin receptor (IGF-1R/IR), Akt, extracellular signal-regulated kinase (ERK), and mTOR. This suggested that metformin indirectly inhibited mTOR in lung tissue by decreasing activation of insulin-like growth factor-I receptor/insulin receptor and Akt upstream of mTOR. Based on these data, we repeated the NNK-induced lung tumorigenesis study using intraperitoneal administration of metformin. Metformin decreased tumor burden by 72%, which correlated with decreased cellular proliferation and marked inhibition of mTOR in tumors. These studies show that metformin prevents tobacco carcinogen-induced lung tumorigenesis and support clinical testing of metformin as a chemopreventive agent.

A central role for Foxp3+ regulatory T cells in K-Ras-driven lung tumorigenesis.

BACKGROUND: K-Ras mutations are characteristic of human lung adenocarcinomas and occur almost exclusively in smokers. In preclinical models, K-Ras mutations are necessary for tobacco carcinogen-driven lung tumorigenesis and are sufficient to cause lung adenocarcinomas in transgenic mice. Because these mutations confer resistance to commonly used cytotoxic chemotherapies and targeted agents, effective therapies that target K-Ras are needed. Inhibitors of mTOR such as rapamycin can prevent K-Ras-driven lung tumorigenesis and alter the proportion of cytotoxic and Foxp3+ regulatory T cells, suggesting that lung-associated T cells might be important for tumorigenesis. METHODS: Lung tumorigenesis was studied in three murine models that depend on mutant K-Ras; a tobacco carcinogen-driven model, a syngeneic inoculation model, and a transgenic model. Splenic and lung-associated T cells were studied using flow cytometry and immunohistochemistry. Foxp3+ cells were depleted using rapamycin, an antibody, or genetic ablation. RESULTS: Exposure of A/J mice to a tobacco carcinogen tripled lung-associated Foxp3+ cells prior to tumor development. At clinically relevant concentrations, rapamycin prevented this induction and reduced lung tumors by 90%. In A/J mice inoculated with lung adenocarcinoma cells resistant to rapamycin, antibody-mediated depletion of Foxp3+ cells reduced lung tumorigenesis by 80%. Likewise, mutant K-Ras transgenic mice lacking Foxp3+ cells developed 75% fewer lung tumors than littermates with Foxp3+ cells. CONCLUSIONS: Foxp3+ regulatory T cells are required for K-Ras-mediated lung tumorigenesis in mice. These studies support clinical testing of rapamycin or other agents that target Treg in K-Ras driven human lung cancer.

Nelfinavir, A lead HIV protease inhibitor, is a broad-spectrum, anticancer agent that induces endoplasmic reticulum stress, autophagy, and apoptosis in vitro and in vivo.

PURPOSE: The development of new cancer drugs is slow and costly. HIV protease inhibitors are Food and Drug Administration approved for HIV patients. Because these drugs cause toxicities that can be associated with inhibition of Akt, an emerging target in cancer, we assessed the potential of HIV protease inhibitors as anticancer agents. EXPERIMENTAL DESIGN: HIV protease inhibitors were screened in vitro using assays that measure cellular proliferation, apoptotic and nonapoptotic cell death, endoplasmic reticulum (ER) stress, autophagy, and activation of Akt. Nelfinavir was tested in non-small cell lung carcinoma (NSCLC) xenografts with biomarker assessment. RESULTS: Three of six HIV protease inhibitors, nelfinavir, ritonavir, and saquinavir, inhibited proliferation of NSCLC cells, as well as every cell line in the NCI60 cell line panel. Nelfinavir was most potent with a mean 50% growth inhibition of 5.2 micromol/L, a concentration achievable in HIV patients. Nelfinavir caused two types of cell death, caspase-dependent apoptosis and caspase-independent death that was characterized by induction of ER stress and autophagy. Autophagy was protective because an inhibitor of autophagy increased nelfinavir-induced death. Akt was variably inhibited by HIV protease inhibitors, but nelfinavir caused the greatest inhibition of endogenous and growth factor-induced Akt activation. Nelfinavir decreased the viability of a panel of drug-resistant breast cancer cell lines and inhibited the growth of NSCLC xenografts that was associated with induction of ER stress, autophagy, and apoptosis. CONCLUSIONS: Nelfinavir is a lead HIV protease inhibitor with pleiotropic effects in cancer cells. Given its wide spectrum of activity, oral availability, and familiarity of administration, nelfinavir is a Food and Drug Administration-approved drug that could be repositioned as a cancer therapeutic.