A mechanistic modeling framework reveals the key principles underlying tumor metabolism

While aerobic glycolysis, or the Warburg effect, has for a long time been considered a hallmark of tumor metabolism, recent studies have revealed a far more complex picture. Tumor cells exhibit widespread metabolic heterogeneity, not only in their presentation of the Warburg effect but also in the nutrients and the metabolic pathways they are dependent on. Moreover, tumor cells can switch between different metabolic phenotypes in response to environmental cues and therapeutic interventions. A framework to analyze the observed metabolic heterogeneity and plasticity is, however, lacking. Using a mechanistic model that includes the key metabolic pathways active in tumor cells, we show that the inhibition of phosphofructokinase by excess ATP in the cytoplasm can drive a preference for aerobic glycolysis in fast-proliferating tumor cells. The differing rates of ATP utilization by tumor cells can therefore drive heterogeneity with respect to the presentation of the Warburg effect. Building upon this idea, we couple the metabolic phenotype of tumor cells to their migratory phenotype, and show that our model predictions are in agreement with previous experiments. Next, we report that the reliance of proliferating cells on different anaplerotic pathways depends on the relative availability of glucose and glutamine, and can further drive metabolic heterogeneity. Finally, using treatment of melanoma cells with a BRAF inhibitor as an example, we show that our model can be used to predict the metabolic and gene expression changes in cancer cells in response to drug treatment. By making predictions that are far more generalizable and interpretable as compared to previous tumor metabolism modeling approaches, our framework identifies key principles that govern tumor cell metabolism, and the reported heterogeneity and plasticity. These principles could be key to targeting the metabolic vulnerabilities of cancer.

Patient-derived iPSCs link elevated mitochondrial respiratory complex I function to osteosarcoma in Rothmund-Thomson syndrome

Rothmund-Thomson syndrome (RTS) is an autosomal recessive genetic disorder characterized by poikiloderma, small stature, skeletal anomalies, sparse brows/lashes, cataracts, and predisposition to cancer. Type 2 RTS patients with biallelic RECQL4 pathogenic variants have multiple skeletal anomalies and a significantly increased incidence of osteosarcoma. Here, we generated RTS patient-derived induced pluripotent stem cells (iPSCs) to dissect the pathological signaling leading to RTS patient-associated osteosarcoma. RTS iPSC-derived osteoblasts showed defective osteogenic differentiation and gain of in vitro tumorigenic ability. Transcriptome analysis of RTS osteoblasts validated decreased bone morphogenesis while revealing aberrantly upregulated mitochondrial respiratory complex I gene expression. RTS osteoblast metabolic assays demonstrated elevated mitochondrial respiratory complex I function, increased oxidative phosphorylation (OXPHOS), and increased ATP production. Inhibition of mitochondrial respiratory complex I activity by IACS-010759 selectively suppressed cellular respiration and cell proliferation of RTS osteoblasts. Furthermore, systems analysis of IACS-010759-induced changes in RTS osteoblasts revealed that chemical inhibition of mitochondrial respiratory complex I impaired cell proliferation, induced senescence, and decreased MAPK signaling and cell cycle associated genes, but increased H19 and ribosomal protein genes. In summary, our study suggests that mitochondrial respiratory complex I is a potential therapeutic target for RTS-associated osteosarcoma and provides future insights for clinical treatment strategies.

The potential skin lightening candidate, senolytic drug ABT263, for photoageing pigmentation

Senescent cells accumulate in several tissues during ageing, including the skin, and contribute to the functional decline of the skin via the senescence-associated secretory phenotypes (SASPs) ¹ . Due to the potential negative effects of SASPs during the ageing process, drugs that selectively target senescent cells or SASPs represent an important therapeutic strategy to delay skin ageing. The selective induction of cell death specifically to kill senescent cells using drugs, referred to as senolytics, is a main approach to achieve this strategy ² .

Analgesic effects of a 5-HT3 receptor antagonist in an animal model of complex regional pain syndrome

OBJECTIVE

Complex regional pain syndrome (CRPS) is caused by injuries from fracture after trauma and orthopaedic surgical procedures in the hind limbs. The symptoms of CRPS include warmth, pain, allodynia, and hyperalgesia. It is known that 5-hydroxytryptamine 3 (5-HT3) receptors contribute to hyperalgesia, but their role has not yet been fully elucidated. This study investigated the mechanism of pain relief when a 5-HT3 receptor antagonist was administered in a CRPS animal model.

MATERIALS AND METHODS

To establish a CRPS animal model, 10-week-old Sprague-Dawley rats were used in the experiment. On the fourth week post tibial fracture surgery, we performed the von Frey test to measure mechanical allodynia. After performing behavioural tests, we collected blood and tissue samples after sacrificing the animals. Enzyme-linked immunosorbent assay and western blot were also performed.

RESULTS

The experimental tibia fracture model-induced CRPS animals elicited increased 5-HT3 receptor expression, and the 5-HT transporter was decreased in the brain stem after 4 weeks of surgical intervention. Additionally, in CRPS-induced animals, both the concentration of substance P and the level of interleukin 6 were increased peripherally and centrally. Treatment with the 5-HT3 receptor antagonist, ramosetron, exerted an analgesic effect in the paw withdrawal test and was dependent on the attenuation of the 5-HT3 receptor population with inflammatory pain mediators.

CONCLUSIONS

These data suggest that treatment with the 5-HT3 receptor antagonist, ramosetron, in experimental CRPS animal models alleviated pain-related behaviours and may be a new therapeutic option or potential therapeutic agent for patients with CRPS.

Short-term outcomes of a multicentre randomized clinical trial comparing laparoscopic pylorus-preserving gastrectomy with laparoscopic distal gastrectomy for gastric cancer (the KLASS-04 trial)

BACKGROUND

There remain concerns about the safety and functional benefit of laparoscopic pylorus-preserving gastrectomy (LPPG) compared with laparoscopic distal gastrectomy (LDG). This study evaluated short-term outcomes of a randomized clinical trial (RCT) comparing LPPG with LDG for gastric cancer.

METHODS

The Korean Laparoendoscopic Gastrointestinal Surgery Study (KLASS)-04 trial was an investigator-initiated, open-label, parallel-assigned, superiority, multicentre RCT in Korea. Patients with cT1N0M0 cancer located in the middle third of the stomach at least 5 cm from the pylorus were randomized to undergo LPPG or LDG. Participants, care givers and those assessing the outcomes were not blinded to group assignment. Outcomes were 30-day postoperative morbidity rate and death at 90 days.

RESULTS

Some 256 patients from nine institutions were randomized (LPPG 129 patients, LDG 127 patients) between July 2015 and July 2017 and outcomes for 253 patients were analysed. Postoperative complications within 30 days were seen in 19.3 and 15.5 per cent in the LPPG and LDG groups respectively (P = 0·419). Postoperative pyloric stenosis was observed in nine (7.2 per cent) and two (1·5 per cent) patients in the LPPG and LDG groups (P = 0·026) respectively. In multivariable analysis higher BMI was a risk factor for postoperative complications (odds ratio 1·17, 95 per cent c.i. 1·04 to 1·32; P = 0·011). Death at 90 days was zero in both groups.

CONCLUSION

Postoperative complications and mortality was comparable in patients undergoing LPPG and LDG. Registration number: NCT02595086 (http://www.clinicaltrials.gov).

A study on the relationship between the rate of vertebral body height loss before balloon kyphoplasty and early adjacent vertebral fracture

BACKGROUND

The number of patients with an osteoporotic vertebral compression fracture, which is often accompanied by lower back pain and restrained activities, is growing. Balloon kyphoplasty involves the inflation of a balloon to restore height and reduce kyphotic deformity before stabilization with polymethylmethacrylate. However, there is a great deal of debate about whether balloon kyphoplasty also increases fracture morbidity by either inducing or facilitating subsequent adjacent vertebral fractures.

OBJECTIVE

To evaluate the relationship between the rate of vertebral body height loss before balloon kyphoplasty and the etiology of early adjacent vertebral fracture after augmentation.

METHODS

A total of 59 patients with osteoporotic vertebral compression fractures who underwent kyphoplasty were enrolled. This study defined early adjacent segmental fractures as new fractures occurring within three months after surgery. This study included the rate of vertebral body height loss.

RESULTS

Early adjacent vertebral fractures were diagnosed in nine (15%) of the 59 patients. The patients were divided into two groups, with and without adjacent vertebral fractures. There was no significant difference in terms of age, body mass index, bone mineral density, local kyphotic angle, Cobb's angle, cement volume, cement leakage, and percent height restored between the groups with fractures and without fractures. There was a statistically significant difference between the two groups in the rate of vertebral body height loss. The rate of vertebral body height loss was significantly higher in the fracture group than in the without fracture group.

CONCLUSIONS

A high rate of vertebral body height loss increased the risk of early adjacent vertebral fractures after balloon kyphoplasty.

Drug-induced Hyperprolactinemia Results in Atypical Atypical Fracture

We report a case of bilateral femur fracture which may have resulted in part from long-term administration of antipsychotic agents. A 43-year-old female patient with pain in both thighs visited our clinic. We conducted X-ray and magnetic resonance imaging (MRI) examinations which revealed bilateral femur fractures. The right proximal femur had a complete fracture, and the left proximal femur had an incomplete fracture, both of which were in the subtrochanteric area. The patient was treated by intramedullary nailing in the right femur. Laboratory analysis showed hyperprolactinemia and hypogonadism. Bone mineral density analysis showed osteoporosis. Antipsychotic drug-induced hyperprolactinemia is a well-known phenomenon. Despite concerns about hyperprolactinemia induced osteoporotic fracture in patients treated with only prolactin-elevating medications, the issue has not been extensively studied. If hyperprolactinemia patients suffer from uncontrolled pain, we recommend MRI examination as surgeons should be aware of the possibility of osteoporotic fracture induced by hyperprolactinemia.

Towards decoding the coupled decision-making of metabolism and epithelial-to-mesenchymal transition in cancer

Cancer cells have the plasticity to adjust their metabolic phenotypes for survival and metastasis. A developmental programme known as epithelial-to-mesenchymal transition (EMT) plays a critical role during metastasis, promoting the loss of polarity and cell-cell adhesion and the acquisition of motile, stem-cell characteristics. Cells undergoing EMT or the reverse mesenchymal-to-epithelial transition (MET) are often associated with metabolic changes, as the change in phenotype often correlates with a different balance of proliferation versus energy-intensive migration. Extensive crosstalk occurs between metabolism and EMT, but how this crosstalk leads to coordinated physiological changes is still uncertain. The elusive connection between metabolism and EMT compromises the efficacy of metabolic therapies targeting metastasis. In this review, we aim to clarify the causation between metabolism and EMT on the basis of experimental studies, and propose integrated theoretical-experimental efforts to better understand the coupled decision-making of metabolism and EMT.

Airflow limitation as a risk factor for vascular stiffness

BACKGROUND: Cardiovascular disease is one of the main causes of mortality in patients with chronic obstructive pulmonary disease (COPD), and atherosclerosis is a cause of cardiac comorbidities in COPD. However, it is not clear whether airflow limitation is associated with atherosclerosis irrespective of smoking.OBJECTIVE: To investigate whether airflow limitation is independently associated with vascular stiffness.METHODS: We enrolled 18 893 participants (male 70.5%; mean age 47.5 ± 9.8 years; never smokers 44.2%) who underwent spirometry and brachial-ankle pulse wave velocity (baPWV) as part of a standard health examination at Ajou University Hospital, Suwon, South Korea, from January 2010 to December 2015.We defined vascular peripheral atherosclerosis as baPWV ≥ 1400 cm/s and airflow limitation as pre-bronchodilator ratio of forced expiratory volume in 1 sec (FEV₁) to forced vital capacity (FVC) <70%.RESULTS: Mean baPWV was higher in subjects with airflow limitation (1477.6 ± 331.7 cm/sec, n = 638) than in those without airflow limitation (1344.1 ± 231.8 cm/sec, n = 18255, P < 0.001). In multivariate logistic regression analysis, the following were independent predictors associated with peripheral atherosclerosis (P < 0.05): age, male sex, fasting serum glucose, mean blood pressure, serum leukocyte count, serum low density lipoprotein level and FEV₁.CONCLUSION: Airflow limitation was an independent predictor of vascular stiffness irrespective of smoking history, which suggests that airflow limitation is linked with atherosclerosis.

Ataxia-telangiectasia mutated interacts with Parkin and induces mitophagy independent of kinase activity. Evidence from mantle cell lymphoma

Ataxia telangiectasia mutated (ATM), a critical DNA damage sensor with protein kinase activity, is frequently altered in human cancers including mantle cell lymphoma. Loss of ATM protein is linked to accumulation of nonfunctional mitochondria and defective mitophagy in both murine thymocytes and in ataxia-telangiectasia cells. However, the mechanistic role of ATM kinase in cancer cell mitophagy is unknown. Here, we provide evidence that FCCP-induced mitophagy in mantle cell lymphoma and other cancer cell lines is dependent on ATM but independent of its kinase function. While Granta-519 mantle cell lymphoma cells possess single copy kinase-dead ATM and are resistant to FCCP-induced mitophagy, both Jeko-1 and Mino cells are ATMproficient and induce mitophagy. Stable knockdown of ATM in Jeko-1 and Mino cells conferred resistance to mitophagy and was associated with reduced ATP production, oxygen consumption, and increased mitochondrial reactive oxygen species. ATM interacts with the E3 ubiquitin ligase Parkin in a kinase-independent manner. Knockdown of ATM in HeLa cells resulted in proteasomal degradation of GFP-Parkin which was rescued by the proteasome inhibitor, MG132, suggesting that the ATMParkin interaction is important for Parkin stability. Neither loss of ATM kinase activity in primary B-cell lymphomas nor inhibition of ATM kinase in mantle cell lymphoma, ataxia-telangiectasia and HeLa cell lines mitigated FCCP- or CCCP-induced mitophagy suggesting that ATM kinase activity is dispensable for mitophagy. Malignant B-cell lymphomas without detectable ATM, Parkin, Pink1, and Parkin-Ub^Ser65 phosphorylation were resistant to mitophagy, providing the first molecular evidence of the role of ATM in mitophagy in mantle cell lymphoma and other B-cell lymphomas.

Computer-Aided Diagnostic System for Thyroid Nodules on Ultrasonography: Diagnostic Performance Based on the Thyroid Imaging Reporting and Data System Classification and Dichotomous Outcomes

BACKGROUND AND PURPOSE

Artificial intelligence-based computer-aided diagnostic systems have been introduced for thyroid cancer diagnosis. Our aim was to compare the diagnostic performance of a commercially available computer-aided diagnostic system and radiologist-based assessment for the detection of thyroid cancer based on the Thyroid Imaging Reporting and Data Systems (TIRADS) and dichotomous outcomes.

MATERIALS AND METHODS

In total, 372 consecutive patients with 454 thyroid nodules were enrolled. The computer-aided diagnostic system was set up to render a possible diagnosis in 2 formats, the Korean Society of Thyroid Radiology (K)-TIRADS and the American Thyroid Association (ATA)-TIRADS-classifications, and dichotomous outcomes (possibly benign or possibly malignant).

RESULTS

The diagnostic sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the computer-aided diagnostic system for thyroid cancer were, respectively, 97.6%, 21.6%, 42.0%, 93.9%, and 49.6% for K-TIRADS; 94.6%, 29.6%, 43.9%, 90.4%, and 53.5% for ATA-TIRADS; and 81.4%, 81.9%, 72.3%, 88.3%, and 81.7% for dichotomous outcomes. The sensitivities of the computer-aided diagnostic system did not differ significantly from those of the radiologist (all P > .05); the specificities and accuracies were significantly lower than those of the radiologist (all P < .001). Unnecessary fine-needle aspiration rates were lower for the dichotomous outcome characterizations, particularly for those performed by the radiologist. The interobserver agreement for the description of K-TIRADS and ATA-TIRADS classifications was fair-to-moderate, but the dichotomous outcomes were in substantial agreement.

CONCLUSIONS

The diagnostic performance of the computer-aided diagnostic system varies in terms of TIRADS classification and dichotomous outcomes and relative to radiologist-based assessments. Clinicians should know about the strengths and weaknesses associated with the diagnosis of thyroid cancer using computer-aided diagnostic systems.

Properties of ^{187}Ta Revealed through Isomeric Decay

Mass-separated ^{187}Ta_{114} in a high-spin isomeric state has been produced for the first time by multinucleon transfer reactions, employing an argon gas-stopping cell and laser ionization. Internal γ rays revealed a T_{1/2}=7.3±0.9  s isomer at 1778±1  keV, which decays through a rotational band with perturbations associated with the approach to a prolate-oblate shape transition. Model calculations show less influence from triaxiality compared to heavier elements in the same mass region. The isomer-decay reduced E2 hindrance factor f_{ν}=27±1 supports the interpretation that axial symmetry is approximately conserved.

Effects of anti-resorptive drugs on implant survival and peri-implantitis in patients with existing osseointegrated dental implants: a retrospective cohort study

The effect of anti-resorptive drug (ARD) usage among patients with successful dental implant osseointegration is controversial. This study showed an increased risk of implant failure in ARD users. Risk factors included pre-existing marginal bone loss, overdenture, diabetes, and a short interval between implant placement and ARD administration.

INTRODUCTION

This retrospective study aimed to determine whether anti-resorptive drug (ARD) usage increased risk of implant failure among patients with successful implant osseointegration. Additionally, the study investigated risk factors that affected implant survival rate in ARD users.

METHODS

Eighty ARD users with 344 implants who had more than 12 months of follow-up from the initiation of ARD treatment during the period between 2008 and 2017 were included, along with 80 non-ARD users from the same period. The primary outcome was dental implant survival. Kaplan-Meier survival curves and Cox proportional hazard models were used for survival analysis.

RESULTS

Average follow-up was 85.3 months. Implant survival rates were 89.83% in ARD users and 96.03% in non-ARD users. In the univariate Cox proportional hazard model, risk of implant failure was significantly higher in patients with pre-existing marginal bone loss (MBL), diabetes, and concurrent bone augmentation. However, risk of implant failure was significantly lower when the interval between implant placement and ARD administration was < 36 months. Compared with overdenture, single crown and fixed splinted users had lower risk of implant failure. In multivariate analysis, variables including pre-existing MBL, diabetes, < 36-month interval between implant placement and ARD treatment, and usage of fixed splinted prosthesis were significantly associated with increased risk of implant failure.

CONCLUSIONS

ARD administration after implant osseointegration was correlated with a reduced implant survival rate. Pre-existing MBL, diabetes, type of final prosthesis, and the interval between implant placement and initiation of ARD administration influenced risk of implant failure.

Upregulation of virulence genes promotes Vibrio cholerae biofilm hyperinfectivity

Vibrio cholerae remains a major global health threat, disproportionately impacting parts of the world without adequate infrastructure and sanitation resources. In aquatic environments, V. cholerae exists both as planktonic cells and as biofilms, which are held together by an extracellular matrix. V. cholerae biofilms have been shown to be hyperinfective, but the mechanism of hyperinfectivity is unclear. Here we show that biofilm-grown cells, irrespective of the surfaces on which they are formed, are able to markedly outcompete planktonic-grown cells in the infant mouse. Using an imaging technique designed to render intestinal tissue optically transparent and preserve the spatial integrity of infected intestines, we reveal and compare three-dimensional V. cholerae colonization patterns of planktonic-grown and biofilm-grown cells. Quantitative image analyses show that V. cholerae colonizes mainly the medial portion of the small intestine and that both the abundance and localization patterns of biofilm-grown cells differ from that of planktonic-grown cells. In vitro biofilm-grown cells activate expression of the virulence cascade, including the toxin coregulated pilus (TCP), and are able to acquire the cholera toxin-carrying CTXФ phage. Overall, virulence factor gene expression is also higher in vivo when infected with biofilm-grown cells, and modulation of their regulation is sufficient to cause the biofilm hyperinfectivity phenotype. Together, these results indicate that the altered biogeography of biofilm-grown cells and their enhanced production of virulence factors in the intestine underpin the biofilm hyperinfectivity phenotype.

Association between body mass index and stroke severity in acute ischaemic stroke with non-valvular atrial fibrillation

BACKGROUND AND PURPOSE

The objective of this study was to investigate the association between body mass index (BMI) and both initial stroke severity at presentation and functional outcomes after acute ischaemic stroke (AIS) in patients with non-valvular atrial fibrillation (NVAF).

METHODS

Patients were categorized on the basis of their BMI into underweight (BMI <18.5, n = 111), normal (18.5 ≤ BMI <25, n = 1036) and overweight to obese (BMI ≥25, n = 472) groups. Initial stroke severity was assessed using the National Institutes of Health Stroke Scale (NIHSS) score and functional outcomes were assessed using the modified Rankin Scale score at discharge. The differences in stroke severity and functional outcomes were compared between groups using robust log-linear regression with a Poisson distribution and binary logistic regression analysis.

RESULTS

A total of 1619 AIS patients with NVAF from six hospitals were included. Compared with the NIHSS scores [median 5, interquartile range (IQR) 2-14] of normal-weight patients, the NIHSS scores (median 9, IQR 4-19) of underweight patients were more likely to be higher, whereas those of overweight to obese patients were lower (median 4, IQR 1-12) (P < 0.001). In terms of functional outcomes after stroke, underweight patients had a higher risk of poor functional outcomes (odds ratio 1.78, 95% confidence interval 1.09-2.56, P = 0.01) but overweight to obese patients had no significant difference in functional outcomes compared with normal-weight patients.

CONCLUSION

An inverse association was found between BMI and stroke severity in AIS patients with NVAF. This suggests the presence of an obesity paradox for short-term outcomes in patients with NVAF.

The effects of betaine supplementation in diets containing different levels of crude protein and methionine on the growth performance, blood components, total tract nutrient digestibility, excreta noxious gas emission, and meat quality of the broiler chickens

The effects of betaine supplementation on growth performance, blood components, nutrient digestibility, excreta noxious gas emission, and meat quality of broiler chickens were examined using different dietary crude protein (CP) and methionine (Met) levels. A total of 768 Ross 308 broiler chickens were allotted to four treatments, with 12 replications of each treatment conducted over 6 wk. Treatments were factorially designed, with 2 levels of CP [Starter: CP 21% (low Met) and 23% (high Met); Finisher: CP 18% (low Met) and 20% (high Met)] and 2 levels of betaine supplementation (0 and 0.12%). Body weight gain and feed conversion improved significantly as dietary levels of protein increased (P < 0.05), but the results for betaine supplementation differed. The concentrations of serum total protein, albumin, and glutathione peroxidase (GPx) were elevated by either the supplementary betaine or the CP (P < 0.05). In addition, serum albumin concentration significantly increased in groups fed low CP amounts and betaine 0.12% compared with groups fed low CP only (P < 0.05). Total tract digestibility of nitrogen in broilers fed high CP amounts or 0.12% betaine, was observed to be greater than that in groups fed low CP amounts or no betaine treatment (P < 0.05). Supplemental betaine affected excreta ammonia gas emission, and hydrogen sulfide concentrations decreased significantly in low CP-fed groups (P < 0.05). Breast meat quality and relative organ weights were not influenced by CP levels or dietary betaine supplementation. These results suggest that betaine does not increase productivity, but may affect serum total protein, albumin, GPx, excreta ammonia emission, and nitrogen digestibility in broiler chickens. In addition, betaine supplementation is more effective in increasing serum albumin concentration when it was added in low CP (low Met) diets.

Abstract P3-06-16: Synergistic effect of biguanides and fatty acid β-oxidation inhibitor in triple-negative breast cancers

Triple negative breast cancer (TNBC) is one of non-targetable cancers which are still poorly understood for the driver pathways and therapeutic targets. Over the past decade, cancer metabolism researches have a huge advance. Thus, it has enhanced our understanding on metabolic reprogramming in cancer therapy. We have previously shown that metabolic reprogramming to fatty acid β-oxidation (FAO) is a key energy metabolic pathway in TNBC. Moreover, we reported that FAO regulates c-Src, one of the frequently upregulated oncopathways in TNBC via autophosphorylation of Src at Y419. However, single treatment by FAO inhibitor alone cannot effectively control the tumor progression in TNBC because of metabolic reprogramming and flexibility of tumors. Therefore, proper combination therapies with other metabolic targets are necessary.

Recently increasing studies demonstrate that anti-diabetic biguanides have attractive anti-cancer effect in various cancer types including breast cancer (BC). However, its significance as an anti-cancer drug is not well established due to parallel metabolic pathways that support tumor growth. Biguanide like metformin is the most widely administered anti-diabetic agent worldwide. Phenformin, a biguanide derivative similar to metformin, has a greater potency than metformin. Like metformin, phenformin also inhibits mitochondrial electron transport chain (ETC) through complex I inhibition. In addition, biguanides lead to the activation of AMPK, which plays a important role in insulin signaling and energy sensing. Importantly, AMPK is an upstream regulator of FAO pathway because it can phosphorylate ACC to activate FAO. Considering the dependency of TNBC to FAO, we evaluated the therapeutic significance of the combination of biguanides (ETC inhibitors) and FAO inhibitors in TNBC progression and metastasis. And we investigated that targeting both ‘arms’ of the pathway can provide more effective and durable responses in TNBC treatments. Our various in vitro and in vivo studies using TNBC cell lines and PDX models suggest that the combination of both inhibitors can provide better therapeutic benefits in TNBCs. This is a rationale and cost-effective metabolic approach to overcome the currently non-targetable TNBCs. Further study toward the clinical effectiveness of this combination may offer better treatment opportunities for TNBC patients.

Citation Format: Jun Hyoung Park, Kwang Hwa Jung, Dongya Jia, Benny A Kaipparettu. Synergistic effect of biguanides and fatty acid β-oxidation inhibitor in triple-negative breast cancers [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P3-06-16.

Abstract P3-10-03: Exploiting p53-dependent functional duality of estrogen receptor-beta to repurpose tamoxifen for triple negative breast cancer therapy

Whether estrogen receptor beta (ERβ/ESR2) is a pro- or anti-oncogenic protein in breast cancer has been controversial. ERβ levels are generally high in triple-negative breast cancer (TNBC). Reports including the Cancer Genome Atlas (TCGA) show that about 80% of TNBC express mutant p53 and it is a major driver of these cancers. We tested the hypothesis that WT versus mutant status of p53 will have an important role in determining the duality of ERβ functions. We showed that ERβ directly binds to TP53 in human breast cancer cells. Using glutathione-S-transferase (GST)-pull down and co-imunoprecipitation assays, we have delineated the DNA binding domain (DBD) along with the hinge domain of ERβ and the C-terminal regulatory domain of p53 to be essential for the interaction. The highly sensitive in situ proximity ligation assay (PLA) showed that ERβ is capable of interacting with both wild type (WT) and mutant p53 in breast cancer cells and tumor tissues. ERβ and p53 antibodies validated for specificity were used for all experiments. Combination of proliferation, cell cycle, and apoptosis assays, RNAi technology, quantitative ChIP (qChIP), and real-time PCR (qRT-PCR) showed that ERβ is pro-proliferative in the context of WTp53, whereas it is anti-proliferative in the context of mutant p53 in multiple breast cancer cell lines. The p53-dependent diametrically opposite functions of ERβ were recapitulated in isogenic MDA-MB-231 TNBC cells (generated by CRISPR) that differ only in the presence of WT versus mutant p53. A major gain-of-function of mutant p53 is its ability to bind and inactivate tumor suppressor p73. We show that ERβ binds and sequesters mutant p53 from mutant p53−p73 complex leading to reactivation of p73. Consistent with these observations, immunohistochemistry (IHC) in TNBC patient tumor tissue microarray (TMA) showed that patients with tumors expressing mutant p53 along with high levels of ERβ were of smaller size and lower stage. Complementing these findings, our analysis of the subgroup of the basal-like/TNBC tumors expressing mutant p53 (but not WTp53) in the METABRIC dataset showed that patients with tumors expressing higher levels of ERβ RNA (ESR2) had significantly better breast cancer-specific survival. The finding that ERβ–mutant p53 combination prognosticates survival in TNBC is important as to date there are no effective prognostic markers for TNBC and suggest the potential for using ERβ−mutant p53 combination in stratification of TNBC into therapeutically actionable subgroups.Furthermore, our findings provide a mechanistic explanation for the functional duality of ERβ and the controversy over its pro-versus anti-tumorigenic role.Surprisingly, Tamoxifen (Tam) increased ERβ-mut-p53 interaction in TNBC cells leading to increased transcription of anti-proliferation genes and knockdown experiments showed that the effect on transcription was dependent on both p73 and ERβ. Importantly, when combined with doxorubicin (Adriamycin) Tam decreased several fold the IC50 of doxorubicin resulting in increased apoptosis. The combination was more effective in inhibiting TNBC xenograft tumor growth in vivo compared to either treatment alone. Significant clinical implications of these findings include the potential for treating patients with doxorubicin at much lower dose than what is currently used in the management of TNBC, thereby reducing its major cumulative dose side effects. Importantly, although at present Tam is not indicated for TNBC, our data suggest the possibility for repurposing Tam therapy alone or in combination with chemotherapy to treat TNBC stratified based on ERβ and p53 status. If validated in a clinical trial, our findings could lead to a therapy that is fundamentally better in terms of effectiveness, cost and time needed to reach the TNBC patients.

Citation Format: Gokul M Das, Utpal K Mukhopadhyay, Chetan C Oturkar, Christina Adams, Nadi Wickramasekera, Sanjay Bansal, Rajesh Medisetty, Austin Miller, Wendy M Swetzig, Laxmi Silwal-Pandit, Anne-Lise Borresen-Dale, Creighton J Creighton, Jun Hyoung Park, Santhi D Konduri, Alka Mukhopadhyay, Alexander Caradori, Benny Abraham Kaipparettu. Exploiting p53-dependent functional duality of estrogen receptor-beta to repurpose tamoxifen for triple negative breast cancer therapy [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P3-10-03.