Therapeutic Response Of Tumors Research Articles

Cancer cell membrane-camouflaged CuPt nanoalloy boosts chemotherapy of cisplatin prodrug to enhance anticancer effect and reverse cisplatin resistance of tumor

The biotoxicity and chemotherapeutic resistance of cisplatin (CDDP) pose a challenge for tumor therapy. Practically, the change in the therapeutic response of tumor from resistance to sensitivity are impressive but challenging. To this end, we propose a strategy of “one stone, three birds” by designing a CuPt nanoalloy to simultaneously eliminate GSH, relieve hypoxia, and promote ROS production for effectively reversing the platinum (IV) (Pt(IV), (c,c,t-[Pt(NH3)2Cl2(OOCCH2CH2COOH)2)) resistance. Notably, the CuPt nanoalloy exhibits ternary catalytic capabilities including mimicking GSH oxidase, catalase and peroxidase. With the subsequent disguise of tumor cell membrane, the CuPt nanoalloy is conferred with homologous targeting ability, making it actively recognize tumor cells and then effectively internalized by tumor cells. Upon entering tumor cell, it gives rise to GSH depletion, hypoxia relief, and oxidative stress enhancement by catalyzing the reaction of GSH and H2O2, which mitigates the vicious milieu and ultimately reinforces the tumor response to Pt(IV) treatment. In vivo results prove that combination therapy of mCuPt and Pt(IV) realizes the most significant suppression on A549 cisplatin-resistant tumor. This study provides a potential strategy to design novel nanozyme for conquering resistant tumor.

Leveraging circulating microbiome signatures to predict tumor immune microenvironment and prognosis of patients with non-small cell lung cancer

BackgroundAccumulating evidence supports the significant role of human microbiome in development and therapeutic response of tumors. Circulating microbial DNA is non-invasive and could show a general view of the microbiome of host, making it a promising biomarker for cancers. However, whether circulating microbiome is associated with prognosis of non-small cell lung cancer (NSCLC) and its potential mechanisms on tumor immune microenvironment still remains unknown.MethodsThe blood microbiome data and matching tumor RNA-seq data of TCGA NSCLC patients were obtained from Poore’s study and UCSC Xena. Univariate and multivariate Cox regression analysis were used to identify circulating microbiome signatures associated with overall survival (OS) and construct the circulating microbial abundance prognostic scoring (MAPS) model. Nomograms integrating clinical characteristics and circulating MAPS scores were established to predict OS rate of NSCLC patients. Joint analysis of blood microbiome data and matching tumor RNA-seq data was used to deciphered the tumor microenvironment landscape of patients in circulating MAPS-high and MAPS-low groups. Finally, the predictive value of circulating MAPS on the efficacy of immunotherapy and chemotherapy were assessed.ResultsA circulating MAPS prediction model consisting of 14 circulating microbes was constructed and had an independent prognostic value for NSCLC. The integration of circulating MAPS into nomograms may improve the prognosis predictive power. Joint analysis revealed potential interactions between prognostic circulating microbiome and tumor immune microenvironment. Especially, intratumor plasma cells and humoral immune response were enriched in circulating MAPS-low group, while intratumor CD4 + Th2 cells and proliferative related pathways were enriched in MAPS-high group. Finally, drug sensitivity analysis indicated the potential of circulating MAPS as a predictor of chemotherapy efficacy.ConclusionA circulating MAPS prediction model was constructed successfully and showed great prognostic value for NSCLC. Our study provides new insights of interactions between microbes, tumors and immunity, and may further contribute to precision medicine for NSCLC.

Emerging Potential Mechanism and Therapeutic Target of Ferroptosis in PDAC: A Promising Future.

Pancreatic cancer (PC) is a devastating malignant tumor of gastrointestinal (GI) tumors characterized by late diagnosis, low treatment success and poor prognosis. The most common pathological type of PC is pancreatic ductal adenocarcinoma (PDAC), which accounts for approximately 95% of PC. PDAC is primarily driven by the Kirsten rat sarcoma virus (KRAS) oncogene. Ferroptosis was originally described as ras-dependent cell death but is now defined as a regulated cell death caused by iron accumulation and lipid peroxidation. Recent studies have revealed that ferroptosis plays an important role in the development and therapeutic response of tumors, especially PDAC. As the non-apoptotic cell death, ferroptosis may minimize the emergence of drug resistance for clinical trials of PDAC. This article reviews what has been learned in recent years about the mechanisms of ferroptosis in PDAC, introduces the association between ferroptosis and the KRAS target, and summarizes several potential strategies that are capable of triggering ferroptosis to suppress PDAC progression.

Myricetin activates the Caspase-3/GSDME pathway via ER stress induction of pyroptosis in lung cancer cells.

Pyroptosis is related to the occurrence, development, and therapeutic response of tumors, mediated by the proteins of the Gasdermin family. These proteins have become potential biomarkers for cancer treatment, and their agonists are likely to become a new direction in research and development of antitumor drugs. In this study, we found that myricetin has an inhibitory effect on lung cancer cells of the activation of pyroptosis. Analysis of the expression of Gasdermin family proteins revealed that this phenomenon was caused by the cleavage of GSDME. Subsequently, specific inhibitors, we found that caspase-3 was its upstream activation factor. In addition, mitochondrial and endoplasmic reticulum (ER) analysis showed that myricetin can cause endoplasmic reticulum stress and increase reactive oxygen species (ROS) levels. Subsequent inhibition of caspase-12 revealed that the expression levels of cleaved-caspase-3 and cleaved-GSDME were significantly reduced, resulting in the inhibition of pyroptosis. Using in vivo experiments, we also found that the treatment with myricetin can reduce tumor volume and significantly increase the level of pyroptosis-related proteins in tumor tissues. Overall, our findings show that myricetin induces cell death of lung cancer cells primarily through an ER stress pathway-induced pyroptosis. Therefore, myricetin has the potential to be used as a pyroptosis agonist in research and development of antitumor drugs.

Delivery of anti-cancer drugs using microbubble-assisted ultrasound in digestive oncology: From preclinical to clinical studies

Introduction The combination of microbubbles (MBs) and ultrasound (US) is an emerging method for the noninvasive and targeted enhancement of intratumor chemotherapeutic uptake. This method showed an increased local drug extravasation in tumor tissue while reducing the systemic adverse effects in various tumor models. Area covered We focused on preclinical and clinical studies investigating the therapeutic efficacy and safety of this technology for the treatment of colorectal, pancreatic and liver cancers. We discussed the limitations of the current investigations and future perspectives. Expert opinion The therapeutic efficacy and the safety of delivery of standard chemotherapy regimen using MB-assisted US have been mainly demonstrated in subcutaneous models of digestive cancers. Although some clinical trials on pancreatic ductal carcinoma and hepatic metastases from various digestive cancers have shown promising results, successful evaluation of this method in terms of US settings, chemotherapeutic schemes and MBs-related parameters will need to be addressed in more relevant preclinical models of digestive cancers, in small and large animals before fully and successfully translating this technology for clinic use. Ultimately, a clear evidence of the correlation between the enhanced intratumoral concentrations of therapeutics and the increased therapeutic response of tumors have to be provided in clinical trials.

Emerging roles of protein palmitoylation and its modifying enzymes in cancer cell signal transduction and cancer therapy.

Protein palmitoylation is an increasingly investigated form of post-translational lipid modification that affects protein localization, accumulation, secretion and function. Recently, emerging findings have revealed that protein palmitoylation is crucial for many tumor-related signaling pathways, such as EGFR, RAS, PD-1/PD-L1 signaling, affecting the occurrence, progression and therapeutic response of tumors. Protein palmitoylation and its modifying enzymes, including palmitoylases and depalmitoylases, are expected to be new targets for effective tumor treatment. Recognizing the significance of palmitoylation modification on protein stability, localization and downstream signal regulation, this review focuses on the regulatory roles of protein palmitoylation and its modifying enzymes in tumor cell signal transduction, aiming to bring new ideas for effective cancer prevention and treatment.

Assessing the therapeutic response of tumors to hypoxia-targeted prodrugs with an in silico approach.

Tumor hypoxia is commonly recognized as a condition stimulating the progress of the aggressive phenotype of tumor cells. Hypoxic tumor cells inhibit the delivery of cytotoxic drugs, causing hypoxic areas to receive insufficient amounts of anticancer agents, which results in adverse treatment responses. Being such an obstruction to conventional therapies for cancer, hypoxia might be considered a target to facilitate the efficacy of treatments in the resistive environment of tumor sites. In this regard, benefiting from prodrugs that selectively target hypoxic regions remains an effective approach. Additionally, combining hypoxia-activated prodrugs (HAPs) with conventional chemotherapeutic drugs has been used as a promising strategy to eradicate hypoxic cells. However, determining the appropriate sequencing and scheduling of the combination therapy is also of great importance in obtaining favorable results in anticancer therapy. Here, benefiting from a modeling approach, we study the efficacy of HAPs in combination with chemotherapeutic drugs on tumor growth and the treatment response. Different treatment schedules have been investigated to see the importance of determining the optimal schedule in combination therapy. The effectiveness of HAPs in varying hypoxic conditions has also been explored in the study. The model provides qualitative conclusions about the treatment response, as the maximal benefit is obtained from combination therapy with greater cell death for highly hypoxic tumors. It has also been observed that the antitumor effects of HAPs show a hypoxia-dependent profile.

Autophagy in the cancer-immunity dialogue.

Autophagy is quintessential for the maintenance of cellular homeostasis in all eukaryotic cells, explaining why both normal and malignant cells benefit from proficient autophagic responses. Moreover, autophagy is intimately involved in the immunological control of malignant transformation, tumor progression and response to therapy. However, the net effect of autophagy activation or inhibition on the natural growth or therapeutic response of tumors evolving in immunocompetent hosts exhibits a considerable degree of context dependency. Here, we discuss the complex cross-talk between autophagy and immuno-oncology as delineated by genetic and pharmacological approaches in mouse models of cancer.

Microwave Ablation and/or Transcatheter Arterial Chemo-embolization in the Treatment of Hepatocellular Carcinoma

Background and study aim: Percutaneous microwave ablation (MWA) and trans-arterial chemo-embolization (TACE) are established therapies for treatment of HCC patients. Lower rates of complete response with mono-therapies have been reported. Therefore, combined treatment strategies, including combined TACE and MWA have been used. The study aimed at comparing the efficacy of MWA mono-therapy; TACE mono-therapy and combined TACE-MWA in the treatment of 3- 5 cm HCC. Patients and methods: The study prospectively included 102 patients with 113 hepatic focal lesions (3-5 cm) diagnosed as HCC by contrast-enhanced triphasic CT or dynamic MRI. Thirty-five HCC in 34 patients were subjected to MWA mono-therapy; 41 HCC in 34 patients were subjected to TACE mono-therapy, while 37 HCC in 34 patients were subjected to combined TACE-MWA therapy. Follow up by contrast-enhanced CT or MRI was done at one month, and every 3 months, up to one year after treatment. Therapeutic tumor response and local tumor progression were evaluated and compared among the groups. Results: After one year follow up, the combined TACE-MWA group showed a higher rate of complete response (CR) (83.3%) when compared to MWA group (76.5%) and TACE group (66.6%) (P>0.05). The local tumor progression (LTP) rate in the combined TACE-MWA group was lower (16.6%) than that in MWA group (23.5%) and TACE group (33.3%) (P=0.2). Conclusion: Combined TACE-MWA therapy appears to be non-significantly superior to MWA mono-therapy and TACE mono-therapy in terms of complete tumor response and local tumor progression in patients with 3-5 cm HCC.

Epithelial-mesenchymal transition: a hallmark in pancreatic cancer stem cell migration, metastasis formation, and drug resistance.

Metastasis, tumor progression, and chemoresistance are the major causes of death in patients with pancreatic ductal adenocarcinoma (PDAC). Tumor dissemination is associated with the activation of an epithelial-to-mesenchymal transition (EMT) process, a program by which epithelial cells lose their cell polarity and cell-to-cell adhesion, and acquire migratory and invasive abilities to become mesenchymal stem cells (MSC). These MSCs are multipotent stromal cells capable of differentiating into various cell types and trigger the phenotypic transition from an epithelial to a mesenchymal state. Therefore, EMT promotes migration and survival during cancer metastasis and confers stemness features to particular subsets of cells. Furthermore, a major problem limiting our ability to treat PDAC is the existence of rare populations of pancreatic cancer stem cells (PCSCs) or cancer-initiating cells in pancreatic tumors. PCSCs may represent sub-populations of tumor cells resistant to therapy which are most crucial for driving invasive tumor growth. These cells are capable of regenerating the cellular heterogeneity associated with the primary tumor when xenografted into mice. Therefore, the presence of PCSCs has prognostic relevance and influences the therapeutic response of tumors. PCSCs express markers of cancer stem cells (CSCs) including CD24, CD133, CD44, and epithelial specific antigen as well as the drug transporter ABCG2 grow as spheroids in a defined growth medium. A major difficulty in studying tumor cell dissemination and metastasis has been the identification of markers that distinguish metastatic cancer cells from cells that are normally circulating in the bloodstream or at sites where these cells metastasize. Evidence highlights a linkage between CSC and EMT. In this review, The current understanding of the PCSCs, signaling pathways regulating these cells, PDAC heterogeneity, EMT mechanism, and links between EMT and metastasis in PCSCs are summarised. This information may provide potential therapeutic strategies to prevent EMT and trigger CSC growth inhibition and cell death.

Radiation-Induced Lung Injury (RILI).

Radiation pneumonitis (RP) and radiation fibrosis (RF) are two dose-limiting toxicities of radiotherapy (RT), especially for lung, and esophageal cancer. It occurs in 5–20% of patients and limits the maximum dose that can be delivered, reducing tumor control probability (TCP) and may lead to dyspnea, lung fibrosis, and impaired quality of life. Both physical and biological factors determine the normal tissue complication probability (NTCP) by Radiotherapy. A better understanding of the pathophysiological sequence of radiation-induced lung injury (RILI) and the intrinsic, environmental and treatment-related factors may aid in the prevention, and better management of radiation-induced lung damage. In this review, we summarize our current understanding of the pathological and molecular consequences of lung exposure to ionizing radiation, and pharmaceutical interventions that may be beneficial in the prevention or curtailment of RILI, and therefore enable a more durable therapeutic tumor response.

Cover 2 - In Vitro Prediction of Therapeutic Tumor Response

Cover 2 - In Vitro Prediction of Therapeutic Tumor Response

Highlights of This Issue

Microtubule poisons such as paclitaxel are the most commonly utilized first-line chemotherapeutics. However, chemotherapeutic resistance can occur and the mechanistic understanding by which treatment induces survival is limited. Here, mitotic slippage-induced senescence is identified as a route by which the senescence-associated secretory phenotype (SASP) engenders paracrine tumorigenesis in an autophagy-dependent manner. Combined treatment with autophagy inhibitors resulted in senescence bypass and cell death. Importantly, p53 status was found to dictate success to such combinatorial sensitization. Thus, clinical treatment regimens targeting senescence and SASP could provide an effective combinatorial strategy with anti-mitotic drugs.There is a growing interest in identifying specific tumor cell niches/organs, termed the premetastatic reservoir, where disseminated cancer cells may acquire chemoresistance to remain quiescent for a long-term period. This study demonstrated that the thymus, particularly the atrophied thymus, serves as a premetastatic reservoir for melanoma cells. Chemotherapeutic treatment with doxorubicin initiates activation of p53 in nonmalignant thymic cells: thymic epithelial cells (TECs) and thymocytes, leading to apoptosis in thymocytes and senescence in TECs, cooperatively resulting in a thymic proinflammatory condition. This inflammatory thymic microenvironment, in turn, induces thymus-harboring melanoma cells to acquire chemoresistant features.Retinoblastoma should not be biopsied for fear of extraocular tumor dissemination; thus, tumor DNA is not used for diagnosis or prognosis. The current study demonstrates that tumor-derived cell-free DNA (cfDNA) is present in aqueous humor, the clear fluid in front of the eye, which can be safely sampled. For the first time, these data demonstrate in vivo access to tumor DNA which can be correlated with genomic alterations and therapeutic tumor response. Importantly, chromosome 6p gain was significantly associated with increased odds of an eye failing treatment and ultimately requiring enucleation. Using aqueous as a liquid biopsy provides new insight into tumorigenesis for this rare cancer.An adequate blood supply is critical for the development and progression of solid tumors, such as head and neck squamous cell carcinoma (HNSCC). Ludwig and colleagues describe a new mechanism for angiogenesis in HNSCC driven by tumor-derived exosomes (TEX). These exosomes carry a variety of pro-angiogenic proteins and directly interact with endothelial cells, inducing the formation of new blood vessels. In vivo, TEX enhance vascularization of tumor tissues and facilitate cancer progression. These results emphasize the need for a deeper understanding of this novel angiogenic mechanism and of the role TEX plays in HNSCC progression.

Corrigendum: Modulating the therapeutic response of tumours to dietary serine and glycine starvation.

This corrects the article DOI: 10.1038/nature22056.

Modulating the therapeutic response of tumours to dietary serine and glycine starvation.

The non-essential amino acids serine and glycine are used in multiple anabolic processes that support cancer cell growth and proliferation (reviewed in ref. 1). While some cancer cells upregulate de novo serine synthesis, many others rely on exogenous serine for optimal growth. Restriction of dietary serine and glycine can reduce tumour growth in xenograft and allograft models. Here we show that this observation translates into more clinically relevant autochthonous tumours in genetically engineered mouse models of intestinal cancer (driven by Apc inactivation) or lymphoma (driven by Myc activation). The increased survival following dietary restriction of serine and glycine in these models was further improved by antagonizing the anti-oxidant response. Disruption of mitochondrial oxidative phosphorylation (using biguanides) led to a complex response that could improve or impede the anti-tumour effect of serine and glycine starvation. Notably, Kras-driven mouse models of pancreatic and intestinal cancers were less responsive to depletion of serine and glycine, reflecting an ability of activated Kras to increase the expression of enzymes that are part of the serine synthesis pathway and thus promote de novo serine synthesis.

The Pleiotropic Role of L1CAM in Tumor Vasculature.

Angiogenesis, the formation of new vessels, is a key step in the development, invasion, and dissemination of solid tumors and, therefore, represents a viable target in the context of antitumor therapy. Indeed, antiangiogenic approaches have given promising results in preclinical models and entered the clinical practice. However, in patients, the results obtained so far with antiangiogenic drugs have not completely fulfilled expectations, especially because their effect has been transient with tumors developing resistance and evasion mechanisms. A better understanding of the mechanisms that underlie tumor vascularization and the functional regulation of cancer vessels is a prerequisite for the development of novel and alternative antiangiogenic treatments. The L1 cell adhesion molecule (L1CAM), a cell surface glycoprotein previously implicated in the development and plasticity of the nervous system, is aberrantly expressed in the vasculature of various cancer types. L1CAM plays multiple pro-angiogenic roles in the endothelial cells of tumor-associated vessels, thus emerging as a potential therapeutic target. In addition, L1CAM prevents the maturation of cancer vasculature and its inhibition promotes vessel normalization, a process that is thought to improve the therapeutic response of tumors to cytotoxic drugs. We here provide an overview on tumor angiogenesis and antiangiogenic therapies and summarize the current knowledge on the biological role of L1CAM in cancer vasculature. Finally, we highlight the clinical implications of targeting L1CAM as a novel antiangiogenic and vessel-normalizing approach.

In Vivo Interrogation of the Hypoxic Transcriptome of Solid Tumors: Optimizing Hypoxic Probe Labeling with Laser Capture Microdissection for Isolation of High-Quality RNA for Deep Sequencing Analysis.

Global gene expression analysis is a powerful method for identifying biological networks and regulatory mechanisms that govern cellular or tissue-level responses to physiologic stress. In the context of tumor biology, differential gene expression studies have provided information about the growth, aggressiveness, prognosis, and therapeutic response of tumors in patients. Scientists are using these valuable data to investigate pathways that can be targeted therapeutically with the goal of improving patient outcome. RNA sequencing enables nucleotide resolution of expression of whole transcriptomes, but arrives with a new set of challenges surrounding the management and analysis of large datasets. This chapter aims to review technical advancements to current methods for isolating high-quality RNA for sequencing studies directly from hypoxic tissues and introduces select widely used applications for gene expression analyses of next-generation sequencing data.

Longitudinal evaluation of the metabolic response of a tumor xenograft model to single fraction radiation therapy using magnetic resonance spectroscopy

Proton magnetic resonance spectroscopy (MRS) was used to evaluate the metabolic profile of human glioblastoma multiform brain tumors grown as xenografts in nude mice before, and at multiple time points after single fraction radiation therapy. Tumors were grown over the thigh in 16 mice in this study, of which 5 served as untreated controls and 11 had their tumors treated to 800 cGy with 200 kVp x-rays. Spectra were acquired within 24 h pre-treatment, and then at 3, 7 and 14 d post-treatment using a 9.4 T animal magnetic resonance (MR) system. For the untreated control tumors, spectra (1–2 per mouse) were acquired at different stages of tumor growth. Spectra were obtained with the PRESS pulse sequence using a 3 × 3 × 3 mm3 voxel. Analysis was performed with the LCModel software platform. Six metabolites were profiled for this analysis: alanine (Ala), myo-inositol (Ins), taurine (Tau), creatine and phosphocreatine (Cr + PCr), glutamine and glutamate (Glu + Gln), and total choline (glycerophosphocholine + phosphocholine) (GPC + PCh). For the treated cohort, most metabolite/water concentration ratios were found to decrease in the short term at 3 and 7 d post-treatment, followed by an increase at 14 d post-treatment toward pre-treatment values. The lowest concentrations were observed at 7 d post-treatment, with magnitudes (relative to pre-treatment concentration ratios) of: 0.42 ± 24.6% (Ala), 0.43 ± 15.3% (Ins), 0.68 ± 27.9% (Tau), 0.52 ± 14.6% (GPC+PCh), 0.49 ± 21.0% (Cr + PCr) and 0.78 ± 24.5% (Glu + Gln). Control animals did not demonstrate any significant correlation between tumor volume and metabolite concentration, indicating that the observed kinetics were the result of the therapeutic intervention. We have demonstrated the feasibility of using MRS to follow multiple metabolic markers over time for the purpose of evaluating therapeutic response of tumors to radiation therapy. This study provides supporting evidence that metabolite/water concentration ratios have the potential to be used as biomarkers for the assessment of the response to therapy.

A method to convert MRI images of temperature change into images of absolute temperature in solid tumours

Purpose: During hyperthermia (HT), the therapeutic response of tumours varies substantially within the target temperature range (39–43 °C). Current thermometry methods are either invasive or measure only temperature change, which limits the ability to study tissue responses to HT. This study combines manganese-containing low temperature sensitive liposomes (Mn-LTSL) with proton resonance frequency shift (PRFS) thermometry to measure absolute temperature in tumours with high spatial and temporal resolution using MRI.Methods: Liposomes were loaded with 300 mM MnSO4. The phase transition temperature (Tm) of Mn-LTSL samples was measured by differential scanning calorimetry (DSC). The release of manganese from Mn-LTSL in saline was characterised with inductively coupled plasma atomic emission spectroscopy. A 2T GE small animal scanner was used to acquire dynamic T1-weighted images and temperature change images of Mn-LTSL in saline phantoms and fibrosarcoma-bearing Fisher-344 rats receiving hyperthermia after Mn-LTSL injection.Results: The Tm of Mn-LTSL in rat blood was 42.9 ± 0.2 °C (DSC). For Mn-LTSL samples (0.06 mM–0.5 mM Mn2+ in saline) heated monotonically from 30 °C to 50 °C, a peak in the rate of MRI signal enhancement occurred at 43.1° ± 0.3 °C. The same peak in signal enhancement rate was observed during heating of fibrosarcoma tumours (N = 3) after injection of Mn-LTSL, and the peak was used to convert temperature change images into absolute temperature. Accuracies of calibrated temperature measurements were in the range 0.9–1.8 °C.Conclusion: The release of Mn2+ from Mn-LTSL affects the rate of MR signal enhancement which enables conversion of MRI-based temperature change images to absolute temperature.

Abstract 4793: A novel laser ablation electrospray ionization mass spectrometry (LAESI-MS) platform for biomarker discovery in cancer cells

Abstract Introductory Sentence: LAESI is a novel technique for the direct and rapid interrogation of cancer cells by mass spectrometry (MS) that can be used to identify potential biomarkers in live cell populations. Experimental: Presented in this work, the human leukemic cell line, REH, was cultured under 3 different conditions to represent clinically relevant scenarios. These included media alone or co-culture with human bone marrow or osteoblast cells to represent conditions in which leukemic disease originates and environments in which the therapeutic response of tumors is known to differ. In previous work, REH cells co-cultured with stromal cells have shown increased resistance to chemotherapeutic treatments prompting our interest in evaluating differences in tumor cells exposed to bone marrow microenvironment conditions compared to those deprived of these survival cues. Subsequently, these unique signatures may identify therapeutic targets of interest. To identify potential therapeutic targets, the cells were pelleted using centrifugation, washed twice, and pipetted upon slides for direct LAESI-MS analysis. The LAESI-MS analysis was performed using a Protea DP-1000 LAESI system interfaced to a Waters Synapt G2 mass spectrometer. The mid-IR laser in the DP-1000 had a maximum output energy of 1 mJ, a 200 µm spot size, and an operational frequency of 10 Hz. The MS was continually calibrated using a lockmass of m/z 445.1206 resulting in mass differences typically less than 5 ppm. After LAESI-MS analysis, the data was analyzed using MarkerLynx software and subjected to a principle component analysis (PCA) and orthogonal projections to latent structures discriminant analysis (OPLS-DA) for identification of potential biomarkers from each treatment. Five replicates of each cell population were analyzed for statistical significance and potential biomarkers were searched against online databases based on accurate mass and confirmed using MS/MS where possible. Summary of Data: The LAESI-MS analysis of the REH cell pellets produced several notable differences in the cell populations that could aid in the identification of biomarkers responsible for the increased resistance to chemotherapeutic treatments. The LAESI-MS analysis was very rapid, requiring less than five minutes of analysis time per cell population to get an average “fingerprint” mass spectrum in addition to MS/MS spectra to aid in metabolite verification. Conclusions: LAESI-MS is a rapid analysis technique that can be used for cancer research as applied here to cell populations. A LAESI-MS analysis requires minimal sample pretreatment with simple washing and pelleting of the cells being the only requirement for the analysis. This method allows the direct analysis of live cells, which can ultimately lead to the determination of biomarkers of disease through the comparison of different cell populations. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4793. doi:1538-7445.AM2012-4793