Introduction: Although obesity is associated with adverse cancer outcomes in general, most retrospective clinical studies suggest a beneficial effect of obesity in NSCLC.Methods: Hypothesizing that this "obesity paradox" arises partly from the limitations of using body mass index (BMI) to measure obesity, we quantified adiposity using preoperative computed tomography images. This allowed the specific determination of central obesity as abdominal visceral fat area normalized to total fat area (visceral fat index [VFI]). In addition, owing to the previously reported salutary effect of metformin on high-BMI patients with lung cancer, metformin users were excluded. We then explored associations between visceral obesity and outcomes after surgical resection of stage I and II NSCLC. We also explored potential immunologic underpinnings of such association using complimentary analyses of tumor gene expression data from NSCLC tumors and the tumor transcriptome and immune microenvironment in an immunocompetent model of lung cancer with diet-induced obesity.Results: We found that in 513 patients with stage I and II NSCLC undergoing lobectomy, a high VFI is associated with decreased recurrence-free and overall survival. VFI was also inversely related to an inflammatory transcriptomic signature in NSCLC tumors, consistent with observations made in immunocompetent murine models wherein diet-induced obesity promoted cancer progression while exacerbating elements of immune suppression in the tumor niche.Conclusions: In all, this study uses multiple lines of evidence to reveal the adverse effects of visceral obesity in patients with NSCLC, which align with those found in animal models. Thus, the obesity paradox may, at least in part, be secondary to the use of BMI as a measure of obesity and the confounding effects of metformin use.

Dysregulated protein synthesis is seen in many aggressive cancers, including metastatic breast cancer. However, the specific contributions of certain translation initiation factors to in vivo disease remain undefined. This is particularly true of eIF4B, an RNA-binding protein and cofactor of the RNA helicase eIF4A and associated eIF4F cap-binding complex. While eIF4A, eIF4G, and eIF4E are well-known to contribute to the progression of many cancer types including metastatic breast cancers, the role played by eIF4B in breast cancer remains relatively unclear. We therefore explored how naturally divergent and experimentally modulated eIF4B levels impact tumor growth and progression in well- characterized murine triple negative breast cancer (TNBC) models. Surprisingly, we found that higher eIF4B levels in mouse and human breast cancers were associated with less aggressive phenotypes. shRNA-mediated eIF4B knockdown in TNBC lines failed to markedly alter proliferation and global translation in the cells in vitro and only modestly hindered their growth as primary mammary tumors growth in mice. However, eIF4B knockdown significantly enhanced invasive growth in vitro and exacerbated both tumor burden and mortality relative to nontargeting shRNA controls in a model of metastatic disease. Analysis of eIF4B levels and breast cancer patient survival reinforced a link to better outcomes. Interestingly, low eIF4B expression was also associated with more formidable immune evasion in vitro and in vivo, implicating a novel immunomodulatory role for this factor in the malignant setting that suggests a mode of action beyond its historical role as a co-activator of eIF4A/F.

Metformin, the widely used and studied diabetes drug, has been reported to have anti-cancer effects. However, in retrospective clinical studies, the survival benefit associated with metformin use in cancer patients is often modest. Consequently, the design and conduct of sufficiently powered prospective clinical trials aimed at exploring this drug’s anti-tumor potential are hampered by the absence of predictive biomarkers. Testing the notion that specific patient characteristics such as obesity may impact the relative potency of metformin’s effects on lung cancer survival, we analyzed the patient outcomes of 756 non-small cell lung cancer (NSCLC) cases with early- (stage I/II, n = 490) or late-stage disease (stage III/IV, n = 266) that either did or did not use metformin (n = 121 and 635, respectively) while not receiving neoadjuvant therapy. We found that metformin use is associated with improved overall and recurrence free survival only in overweight and obese patients defined by a body mass index (BMI) greater than 25 kg/m2. Corroborative findings obtained from immunocompetent mouse lung cancer models aligned with these observations. In these studies, despite supporting accelerated growth of both primary and metastatic tumors compared to their normal weight counterparts, animals subjected to diet induced obesity (DIO) experienced significantly reduced tumor development upon metformin treatment. In contrast, the drug had little-to-no effect on tumor burden in normal weight controls. Furthermore, while flow cytometric evaluation of obese mouse-derived tumors identified several previously described mediators of immune dysfunction previously described in animals with DIO (e.g., widespread up-regulation of the immune checkpoint factors PD-1 and Lag3, elevated suppressor cell proportions and activity), metformin treatment was associated with their reversal specifically in the tumors of obese mice. Interestingly, the drug had little effect on the tumor immune contexture of normal weight mice, and gene expression analysis failed to reveal considerable alterations in canonical cancer pathways. Thus, our preclinical and clinical studies suggest that the anti-diabetic drug metformin has an anti-cancer effect in NSCLC that is restricted to overweight individuals and reflects its potential to direct favorable, context-specific immune reprogramming. This work also provides the rationale for using high BMI as a predictive biomarker of the anti-cancer effect of metformin in lung cancer. Citation Format: Joseph Barbi, Randall J. Smith, Robert Zollo, Stephanie N. Sass, Deschana Washington, Cara Petrucci, Aravind Srinivasan, Eric Kannisto, Santosh Patnaik, Sai Sai Yendamuri. Obesity dependent benefits of metformin for improved anti-tumor immunity and outcomes in non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2082.

Eukaryotic translation initiation is a critical node at which gene expression is regulated. Among the factors that are known to regulate this process, DEAD‐box RNA helicases are believed to promote translation by resolving secondary structure in the 5′ UTR of an mRNA. These helicases include the protein Ded1 in budding yeast, which is required to remove cap‐distal structure in the 5′ UTR of an mRNA, thus enabling scanning of the preinitiation complex. Yet the role of Ded1 in translation is complex; a translationally repressive role has also been demonstrated by Ded1 overexpression. Further confounding investigations of Ded1 function are the large number of protein‐protein and protein‐RNA contacts made by Ded1 to regulate activity. To study the diverse roles that Ded1 plays in translation, we have developed a system that reports on Ded1‐specific changes in translation in vivo. This system relies on a fluorescence‐based reporter that simultaneously promotes the transcription of two mRNA transcripts: one encoding RFP with a 5′ UTR that is translated independent of Ded1 activity, and the other encoding GFP with a 5′ UTR that requires Ded1‐activity for translation. We are using this system in combination with a library of random Ded1 mutants to broadly interrogate Ded1 activities for effects on translation initiation and repression. Support or Funding Information This work was supported by NIH grant R00GM119173 and start‐up funds from SUNY at Buffalo, College of Arts and Sciences.