Alanine supplementation exploits glutamine dependency induced by SMARCA4/2-loss

SMARCA4 (BRG1) and SMARCA2 (BRM) are the two paralogous ATPases of the SWI/SNF chromatin remodeling complexes frequently inactivated in cancers. Cells deficient in either ATPase have been shown to depend on the remaining counterpart for survival. Contrary to this paralog synthetic lethality, concomitant loss of SMARCA4/2 occurs in a subset of cancers associated with very poor outcomes. Here, we uncover that SMARCA4/2-loss represses expression of the glucose transporter GLUT1, causing reduced glucose uptake and glycolysis accompanied with increased dependency on oxidative phosphorylation (OXPHOS); adapting to this, these SMARCA4/2-deficient cells rely on elevated SLC38A2, an amino acid transporter, to increase glutamine import for fueling OXPHOS. Consequently, SMARCA4/2-deficient cells and tumors are highly sensitive to inhibitors targeting OXPHOS or glutamine metabolism. Furthermore, supplementation of alanine, also imported by SLC38A2, restricts glutamine uptake through competition and selectively induces death in SMARCA4/2-deficient cancer cells. At a clinically relevant dose, alanine supplementation synergizes with OXPHOS inhibition or conventional chemotherapy eliciting marked antitumor activity in patient-derived xenografts. Our findings reveal multiple druggable vulnerabilities of SMARCA4/2-loss exploiting a GLUT1/SLC38A2-mediated metabolic shift. Particularly, unlike dietary deprivation approaches, alanine supplementation can be readily applied to current regimens for better treatment of these aggressive cancers.

Risk-focused differences in molecular processes implicated in SARS-CoV-2 infection: corollaries in DNA methylation and gene expression

BACKGROUND

Understanding the molecular basis of susceptibility factors to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is a global health imperative. It is well-established that males are more likely to acquire SARS-CoV-2 infection and exhibit more severe outcomes. Similarly, exposure to air pollutants and pre-existing respiratory chronic conditions, such as asthma and chronic obstructive respiratory disease (COPD) confer an increased risk to coronavirus disease 2019 (COVID-19).

METHODS

We investigated molecular patterns associated with risk factors in 398 candidate genes relevant to COVID-19 biology. To accomplish this, we downloaded DNA methylation and gene expression data sets from publicly available repositories (GEO and GTEx Portal) and utilized data from an empirical controlled human exposure study conducted by our team.

RESULTS

First, we observed sex-biased DNA methylation patterns in autosomal immune genes, such as NLRP2, TLE1, GPX1, and ARRB2 (FDR < 0.05, magnitude of DNA methylation difference Δβ > 0.05). Second, our analysis on the X-linked genes identified sex associated DNA methylation profiles in genes, such as ACE2, CA5B, and HS6ST2 (FDR < 0.05, Δβ > 0.05). These associations were observed across multiple respiratory tissues (lung, nasal epithelia, airway epithelia, and bronchoalveolar lavage) and in whole blood. Some of these genes, such as NLRP2 and CA5B, also exhibited sex-biased gene expression patterns. In addition, we found differential DNA methylation patterns by COVID-19 status for genes, such as NLRP2 and ACE2 in an exploratory analysis of an empirical data set reporting on human COVID-9 infections. Third, we identified modest DNA methylation changes in CpGs associated with PRIM2 and TATDN1 (FDR < 0.1, Δβ > 0.05) in response to particle-depleted diesel exhaust in bronchoalveolar lavage. Finally, we captured a DNA methylation signature associated with COPD diagnosis in a gene involved in nicotine dependence (COMT) (FDR < 0.1, Δβ > 0.05).

CONCLUSION

Our findings on sex differences might be of clinical relevance given that they revealed molecular associations of sex-biased differences in COVID-19. Specifically, our results hinted at a potentially exaggerated immune response in males linked to autosomal genes, such as NLRP2. In contrast, our findings at X-linked loci such as ACE2 suggested a potentially distinct DNA methylation pattern in females that may interact with its mRNA expression and inactivation status. We also found tissue-specific DNA methylation differences in response to particulate exposure potentially capturing a nitrogen dioxide (NO2) effect-a contributor to COVID-19 susceptibility. While we identified a molecular signature associated with COPD, all COPD-affected individuals were smokers, which may either reflect an association with the disease, smoking, or may highlight a compounded effect of these two risk factors in COVID-19. Overall, our findings point towards a molecular basis of variation in susceptibility factors that may partly explain disparities in the risk for SARS-CoV-2 infection.

Carcinoma of the External Auditory Meatus and Middle Ear. Results of the Treatment of 28 Cases

Aims

The authors report their experience on the treatment of 28 cases of middle ear (3) and external auditory meatus (EAM) cancers (25) with surgery and/or radiation therapy. According to histologic type, there were 23 squamous cell carcinomas, 4 basal cell carcinomas and 1 adenocystic carcinoma.

Methods

Surgery alone was performed in 2 cases, surgery combined with radiotherapy in 11 cases, and radiotherapy alone in 15 cases. Postoperative radiation therapy dose ranged between 4500 and 5500 cGy; the definitive dose was 6000-7000 cGy. The median follow-up was 61 months.

Results

Complete respons rate 6 weeks after the end of the treatment, evaluated by CT scan, was 85.7% (24/28). Definitive local control was obtained in 20/28 cases for the primary site and in 26/28 cases for the neck. Nine of the 10 recurrences were retreated with low-dose radiotherapy combined with surgery, chemotherapy or hyperthermia. A new local control was obtained in 2 cases. Four patients were lost during the follw-up at 13, 14, 17 and 23 months after the end of the treatment. The survival rate was 54% (13/24); disease-free survival was 50% (11/22).

Conclusions

Despite a not very aggressive treatment, our results are quite good.

Interstitial Brachytherapy for Carcinomas of the Lower Lip. Results of Treatment

From 1973 to 1988 47 patients with previously untreated T1 and T2 squamous cell carcinomas of the lower lip received a definitive course of interstitial brachytherapy by iridium 192 wires. The disease stage was T1 in 21 cases (44.7 %) and T2 in 26, and NO in all cases except 2 of N1. Radiation therapy dose ranged between 6000 and 8000 cGy. Local control was obtained in 44 patients (93.6 %). Treatment failure in the neck was observed in 3 patients (6.7 %) The 5- and 10-year actuarial disease-free survival rates were 92% and 85%, respectively. A surgical salvage was attempted in 3 patients, with postoperative definitive control of the disease in 2. The 10-year actuarial overall survival was 95 %. The incidence of complications was acceptable (10.6% of mucosal necrosis). An excellent or good cosmetic result was obtained in 91.7% of patients.

Abstract A49: Transcription factor upregulation after mTOR inhibition by Torin1 induces growth factor receptor expression

Introduction: mTOR (mammalian target of rapamycin) integrates signals from cellular nutrient status and growth factors, to regulate cell growth, proliferation, and metabolism. mTOR is a part of the PI3K-Akt-mTOR signalling pathway, the components of which are frequently mutated in human cancers. Various inhibitors of mTOR activity have been developed to target this pathway, including rapamycin and its analogs sirolimus, everolimus, temsirolimus. These inhibitors are currently approved for the treatment of certain cancers, and under investigation in clinical trials for the treatment of others. Despite displaying initial effectiveness in delaying tumor progression, mTOR inhibitors eventually lose efficacy and patients relapse due to development of resistance.

Due to the regulation of cap-dependent translation by mTOR, treatment of cells with mTOR inhibitors inhibits general protein translation. However, a subset of proteins exhibit increased translation in response to mTOR inhibitors. We postulate that these proteins that exhibit upregulation in response to mTOR inhibition play a role in conferring mTOR inhibitor resistance. In this study, we aim to characterize the landscape of proteins that are upregulated in response to mTOR inhibition, in order to identify pathways that contribute to resistance. We use a second-generation mTOR inhibitor Torin1, which targets both mTORC1 and mTORC2 complexes.

Methods: In order to study newly translated proteins after mTOR inhibition by Torin1 on a proteomic scale, we combined the methods of click chemistry with SILAC (stable isotopic labelling of amino acids in cell culture) and tandem mass spectrometry. The translatome was studied through click-pulse-SILAC experiments conducted at 2 hours and 24 hours post Torin1 treatment in MEFs (mouse embryonic fibroblasts) as well as PC3 prostate carcinoma cells. The total proteome of MEF and PC3 cells 24 hours after Torin1 treatment was studied using SILAC and tandem mass spectrometry. Proteomics data processing and pathway enrichment analysis was performed using the Perseus software, and upregulated proteins were subject to analysis by RNA silencing, qPCR, and click chemistry.

Results: Translatome analysis after Torin1 treatment showed general translation inhibition as expected, except for a small subset of proteins with increased translation. Increased translation of growth factor receptors was observed 24 hours post-Torin1 treatment, and of many transcription factors 2 hours post-treatment. Total proteome analysis 24 hours post-treatment revealed an increase in total protein levels of many of these growth factor receptors as well as transcription factors. qPCR experiments revealed increased transcripts levels of these growth factor receptors as early as 2 hours post-treatment, suggesting transcriptional upregulation. Through cross-referencing our 2 hour translatome data with genome-wide ChIP-seq datasets accessed through Cscan, we determined candidate transcription factors that may be responsible for upregulating the expression of growth factor receptors. Knockdown studies suggest that some of these transcription factors are indeed responsible for the upregulation of growth factor receptors.

Conclusion: mTOR inhibition by Torin1 suppresses general translation, but many transcription factors escape this suppression and exhibit increased expression. These transcription factors induce expression of growth factor receptors, consequently enhancing their signaling. These studies identify an axis which potentially reduces the efficacy of mTOR inhibitors in cancer therapy, as well as targets that may require simultaneous inhibition.

Citation Format: Tianqing T. Yang, Gian L. Negri, Anders Kristensen, Poul H. B. Sorensen. Transcription factor upregulation after mTOR inhibition by Torin1 induces growth factor receptor expression. [abstract]. In: Proceedings of the AACR Special Conference on Translational Control of Cancer: A New Frontier in Cancer Biology and Therapy; 2016 Oct 27-30; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2017;77(6 Suppl):Abstract nr A49.

[THe cost of radiotherapy. Piedmontese experience]

INTRODUCTION

An integrated task force of radiotherapists and administrators of the Piedmont region studied the estimated cost of radiotherapy (RT) to compare it with the figures in the 502/92 law modifying the financing of medical structures. This law changed the financing method from productive factors compensation to actually provided performances compensation.

MATERIAL AND METHODS

The RT departments of the Turin and Novara university hospitals, those of Ivrea and Asti and that of the Pinna Pintor Clinic (Turin) participated in the study, with 4889 examinations in the period of interest. The study consisted of 6 steps: 1) defining a nomenclator; 2) making a list of standard resources; 3) calculating the actual resource consumption; 4) relating 2) to 3); 5) calculating cost and times; 6) defining quality standards. A technical and/or a central group(s) carried out all the steps. The nomenclator indicates 13 main activities (e.g., irradiation, telecobalt therapy, brachytherapy, hyperthermia), each of them featuring some subactivities (e.g., telecobalt therapy: flash, a fixed beam, two opposing beams). The following productive factor were considered: a) personnel; b) material; c) investments; d) the service cost; e) general costs. The personnel cost (the main cost) was calculated as: A) routine activity; B) activity for other units; C) congress activity; D) research. The times for individual performances were estimated according to professional roles (e.g., medical doctor, physicist, technician, nurse, administrative) for each subactivity.

RESULTS

The estimated RT costs were as follows (please note that all figures are expressed in US $, at a rate of 1$ = ItL 1700). Irradiation: 15 (cost/session +/- 3%); telecobalt therapy: 30-55; Linac (energy < > 10 Mev): 38-60; special techniques: 931-2,314; HDR brachytherapy: 878-1,515; hyperthermia: 285; simulation: 50-92; dosimetry: 52-286; examination, treatment planning, follow-up, etc.: 24-59; immobilization devices, photographs, etc.: 3-66. The quality criteria are related to the personnel; high energy equipment; treatment planning; 3D dosimetry.

CONCLUSIONS

Our study led the Italian Ministry of Health to revise the estimated cost of RT examinations in July, 1996. We will further enquire into the new figures.

[Radiotherapy results in the treatment of malignant tumors of the nasal fossa and vestibule]

The authors report their personal experience in the treatment of malignant tumors of the nasal cavity and vestibule with irradiation alone or combined with surgery. From January 1976 to December 1989 we treated 40 patients with 22 squamous cell carcinomas, 12 adenocarcinomas or other glandular types, and 6 other histologic types of lesions: 23 patients received irradiation alone and 17 patients were treated with surgery and postoperative irradiation. The protocol included surgery as the treatment of choice: irradiation alone was administered to inoperable tumors or to the patients refusing surgery; postoperative irradiation was given when macroscopic or microscopic residual disease was observed after surgery or to particular histologic types. In the whole series of patients, 3- and 5-year local control rates were 70% and 50%, respectively; better results were obtained in the patients receiving the combined treatment (64% at 5 years) than in the patients receiving irradiation alone (43% at 5 years). Disease stages (I and II versus III and IV) were the only statistically significant prognostic factor; worse results in irradiated patients might be due to the higher rate of advanced lesions in this group. Salvage therapy (irradiation in 8 cases, surgery in 2 and chemotherapy in 1) was successfully performed in 5 of 11 treated patients. The 3- and 5-year overall survival rates were 88% and 70%, respectively. Severe complication rate was lower than 10% (3 cases only).

[The otoneurological assessment of radiotherapy-induced brain stem involvement in patients with rhinopharyngeal neoplasms]

The authors report a study in which otoneurological tests were employed in order to determine the possibility of radio-induced alterations in the brainstem of patients with a rhinopharyngeal carcinoma, which extended to basicranial structures, who had undergone radiotherapy. The case report includes 16 patients; 10 males and 6 females, aged from 37 to 82, all with rhinopharyngeal tumors. All the subjects underwent Co 60 radiotherapy (44-68 Gy); the brainstem received from 40 to 100% of the total dose. Otoneurological evaluation prior to and following radiotherapy was performed employing pure tone audiometry, ABR, rotatory tests, saccadic eye movements, smooth pursuit. After RT treatment, ABR analysis revealed an abnormal wave I-V interpeak interval in 40% of the cases and pathologic in 37%. Smooth pursuit, saccades and sinusoidal rotation analysis showed important alterations respectively in 21%, 6% and 12% of the subjects. The most significant variations were in patients who received more than 60 Gy. The data gathered regarding abnormalities of otoneurological parameters indicate a probable close relationship between these modifications and precocious radio-induced brainstem damage.

[Results of interstitial curietherapy and combined transcutaneous radiotherapy-curietherapy in 150 patients with carcinoma of the tongue and/or mouth floor]

The authors report their experience on the treatment of carcinoma of the oral tongue and floor of the mouth with interstitial brachytherapy, alone or in combination with external irradiation. One hundred and fifty patients were treated; among these, 116 with brachytherapy alone, 34 with combined treatment. The five years local control in those patients treated with brachytherapy alone was 72.5% in T1, 61.2% in T2 and 35% in T3; in those patients treated with external irradiation and brachytherapy the global five years control was 42.5%. The global five years survival was 64% in the patients treated with brachytherapy alone and 48% in the patients treated with combined therapy.

[Chemotherapy of cerebral tumours: data on malignant gliomas (author's transl)]

The Authors, after briefly reviewing the literature on chemotherapy of malignant gliomas, present their own experience on forty-four patients with such tumors. All of them had been previously operated and irradiated. The clinical course was controlled by various parameters which are described. Results obtained in glioblastomas, anaplastic astrocytomas and malignant oligodendrogliomas are discussed. BCNU and CCNU seem to be beneficial not only in prolonging survival time but also in improving its quality: the average survival time of treated patients is 9.2 +/- 9.8 against 6.7 +/- 3.4 of controls. These values however are not statistically significant. In 15 out of 31 patients, who died at varying intervals after chemoterapy, an autopsy was performed. The morphology of the tumors was compared with that of previous biopsies. No specific alterations to be referred to chemotherapy were found. The side effects are described in detail and particular attention is focused on toxicity (blood and liver) whose main effect is the lowering of platelets and white cells. However, this and the epatic alterations did not reach values requiring interruption of chemotherapy. Other drugs have been used such as MeCCNU, VM 26 and Procarbazine. The number of patients, treated with each of them, is low for a definite conclusion; even if VM 26 and Procarbazine seem to offer the best effects.

[Dosimetric experience with mammography]

Dose measurements were carried out during mammography with both conventional films without a reinforcement screen and with Low-dose films, using hot press chip lithium fluoride meters on the breast, sternum, mons Veneris, and the glabella between the supraciliary arches. The results made it clear that there were no dosimetric objections to the large-scale employment of mammography in diagnosis. Value absorbed were lower than those given in the literature for both the conventional and the Low-dose system.

[Results of hyperthermia on the bladder carcinomas of the dog (author's transl)]

A study on the effects of hyperthermia on B.N.A. induced bladder carcinomas of the dog has been carried out since 1966. The hyperthermic treatment has been performed directly in the bladder using an original equipment especially designed. In a large majority of the animals definite cancericidal changes have been shown. The most favorable results were obtained in the treatment of carcinomas not infiltrating the muscular layer of the bladder. In these cases malignant recurrency was not shown up to five years after treatment. Good palliative effect is also refferred in the treatment of advanced bladder carcinoma of the man.