Serine catabolism produces ROS, sensitizes cells to actin dysfunction, and suppresses cell growth in fission yeast

Serine is an essential component in organisms as a building block of biomolecules, a precursor of metabolites, an allosteric regulator of an enzyme, etc. This amino acid is thought to be a key metabolite in human diseases including cancers and infectious diseases. To understand the consequence of serine catabolism, we screened natural products to identify a fungal metabolite chaetoglobosin D (ChD) as a specific inhibitor of fission yeast cell growth when cultivated with serine as a sole nitrogen source. ChD targets actin, and actin mutant cells showed severe growth defect on serine medium. ROS accumulated in cells when cultivated in serine medium, while actin mutant cells showed increased sensitivity to oxidative stress. ROS production is a new aspect of serine metabolism, which might be involved in disease progression, and actin could be the drug target for curing serine-dependent symptoms.

Abstract P6-02-11: The TILs-US scores based on ultrasonography can predict lymphocyte-predominant breast cancer before surgery

[Purpose]

Tumor-infiltrating lymphocytes (TILs) has been shown to be useful for predicting outcomes after surgery in breast cancer, and while TILs can be evaluated in preoperative biopsy tissue, heterogeneous distribution of TILs requires examination of all biopsied tissue samples.

We gave scores to preoperative ultrasonography (US) images with characteristics indicative of lymphocyte-predominant breast cancer (LPBC) and attempted to apply these for diagnostic prediction of LPBC. In this study, TILs-US scores based on preoperative US were assessed for their usefulness in predicting LPBC, the diagnosis of which was confirmed with postoperative pathology.

[Methods]

We evaluated 161 patients with invasive breast cancer between January 2014 and December 2017. All patients were treated by either mastectomy or breast-conserving surgery. Stromal lymphocytes were evaluated on preoperative biopsy tissues and surgical pathological specimens. Breast cancer samples with ≥ 50% stromal TILs were defined as pre-LPBC (preoperative biopsy tissues) and LPBC (surgical pathological specimens). TILs-US score was calculated from US before curative surgery. Based on clinicopathological factors including TILs-US scores based on preoperative US and pre-LPBC indicators, determinants useful for prediction of LPBC were examined.

[Results]

There were 39 cases of LPBCs and 122 cases of non-LPBCs in surgical pathological specimens. We set TILs-US score cut-offs for predicting LPBC at 4 points based on the receiver operating characteristics (ROC) curves (AUC, 0.88). There were significant predictors for LPBC in maltivariate logistic analysis (TILs-US score: OR26.8, p<0.001; pre- LPBC: 18.6, p=0.002; HER-2: OR9.2, p=0.009) in preoperative clinicopathological factor. The sensitivity, specificity and accuracy of TILs-US score for predicting LPBC were 0.74 (0.62-0.84), 0.89 (0.85-0.92) and 0.85 (0.79-0.90). Those of pre-LPBC were 0.51(0.42-0.55), 0.98 (0.96-1.00) and 0.87 (0.82-0.89), and those of HER2 were 0.28(0.19-0.36), 0.94(0.91-0.97) and 0.78 (0.74-0.82), respectively. The sensitivity of TILs-US score for predicting LPBC was significantly greater than those of pre- LPBC (p=0.04) and HER2 (p<0.001). On the other hand, the specificity of pre- LPBC for predicting LPBC was significantly greater than that of TILs-US score(p=0.002).

The sensitivity, specificity and accuracy of predicting LPBCPerformance measureTILs-US score (95%CI)Preoperative biopsyHER-2P, TILs-US score vs. Preoperative biopsyP, TILs-USscore vs. HER-2Sensitivity0.74 (0.62-0.84)0.51 (0.42-0.55)0.28 (0.19-0.36)0.04<0.001Specificity0.89 (0.85-0.92)0.98 (0.96-1.00)0.94 (0.91-0.97)0.0020.11Accuracy0.85 (0.79-0.90)0.87 (0.82-0.89)0.78 (0.74-0.82)0.230.11

[Conclusions]

TILs-US scores are an important factor that can predict LPBC preoperatively. The TILs-US score has particularly high sensitivity and may be an applicable index in the preoperative evaluation for LPBC.

Citation Format: Kanou A, Masumoto N, Shiroma N, Fukui K, Sasada S, Emi A, Kadoya T, Yokozaki M, Arihiro K, Okada M. The TILs-US scores based on ultrasonography can predict lymphocyte-predominant breast cancer before surgery [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-02-11.

Abstract P6-02-06: Characteristics of lymphocyte-predominant breast cancer in ultrasound images and their application to diagnostic prediction

[Purpose]

Tumor-infiltrating lymphocytes (TILs) is a prognostic factor for breast cancer, however, an accurate and simple evaluation method remains elusive. Therefore, we focused on findings characteristic of lymphocyte-predominant breast cancer (LPBC) in ultrasound (US) images. In this study, the application of preoperative US image assessment to diagnostic prediction of LPBC evaluated from postoperative pathological specimens, was appraised.

[Methods]

We evaluated 191 patients with invasive breast cancer between January 2014 and December 2017. All patients were treated by either mastectomy or breast-conserving surgery. Stromal lymphocytes were evaluated on surgical pathological specimens. Breast cancer samples with ≥ 50% stromal TILs were defined as LPBC. Preoperative US was performed in all cases and images were examined for characteristics indicative of TILs. Scores were given to US images with characteristic TILs and these TILs-US scores were assessed for their application to predict LPBC.

[Results]

There were 39 cases of LPBCs and 122 cases of non-LPBCs in surgical pathological specimens.

The characteristic US image findings predicting LPBC were shape (more lobulated), internal echo level (weaker) and posterior echoes (stronger). The TILs-US scores were given based on these three ultrasound tissue characterizations.We set TILs-US score cut-offs for predicting LPBC at 4 points (Sensitivity, 0.73; specificity, 0.87; accuracy, 0.83) based on the receiver operating characteristics (ROC) curves (AUC, 0.88). There were significant predictors for LPBC in maltivariate logistic analysis (Nuclear Grade (NG): OR3.4, p=0.02; ER: 5.7, p =0.007;HER-2: OR4.1, p=0.04; TILs-US score2: OR14.9, p<0.001) in preoperative clinicopathological factor. The sensitivity, specificity and accuracy of NG for predicting LPBC were 0.75, 0.69 and 0.71. Those of ER and HER2 were 0.33, 0.96 and 0.79.Sensitivity, specificity, and accuracy of NG, ER, and HER2 diagnoses were all lower than the TILs-US score, and the TILs-US score showed the best diagnostic ability.

The sensitivity, specificity and accuracy of predicting LPBCPerformance measureTILs-US score (95%CI)NGER or HER-2P, TILs-US score vs. NG,P, TILs-USscore vs. ER or HER-2Sensitivity0.73 (0.63-0.81)0.75 (0.64-0.84)0.327 (0.24-0.39)0.08<0.001specificity0.87 (0.83-0.90)0.69 (0.65-0.72)0.957 (0.93-0.98)<0.001<0.001accuracy0.83 (0.77-0.88)0.707 (0.65-0.376)0.785 (0.74-0.82)0.0040.25

Conclusions

LPBC has characteristic ultrasound tissue characterizations in US images. Thus, TILs-US scores based on US may be applicable to accurate and convenient preoperative diagnosis of LPBC.

Citation Format: Fukui K, Masumoto N, Shiroma N, Kanou A, Yokozaki M, Sasada S, Emi A, Kadoya T, Arihiro K, Okada M. Characteristics of lymphocyte-predominant breast cancer in ultrasound images and their application to diagnostic prediction [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-02-06.

Simultaneous ablation of prmt-1 and prmt-5 abolishes asymmetric and symmetric arginine dimethylations in Caenorhabditis elegans

Protein arginine methyltransferases (PRMTs) catalyze the transfer of a methyl group from S-adenosylmethionine to arginine residues and are classified into two types: type I producing asymmetric dimethylarginine (ADMA) and type II producing symmetric dimethylarginine (SDMA). PRMTs have been shown to regulate many cellular processes, including signal transduction, transcriptional regulation and RNA processing. Since the loss-of-function mutation of PRMT1 and PRMT5, each of which is the predominant type I and II, respectively, causes embryonic lethality in mice, their physiological significance at the whole-body level remains largely unknown. Here, we show the morphological and functional phenotypes of single or double null alleles of prmt-1 and prmt-5 in Caenorhabditis elegans. The prmt-1;prmt-5 double mutants are viable, and exhibit short body length and small brood size compared to N2 and each of the single mutants. The liquid chromatography-tandem mass spectrometry analysis demonstrated that the levels of ADMA and SDMA were abolished in the prmt-1;prmt-5 double mutants. Both prmt-1 and prmt-5 were required for resistance to heat and oxidative stresses, whereas prmt-5 is not involved in lifespan regulation even when prmt-1 is ablated. This mutant strain would be a useful model animal for investigating the role of asymmetric and symmetric arginine dimethylation in vivo.

PRMT-5 converts monomethylarginines into symmetrical dimethylarginines in Caenorhabditis elegans

The transmethylation to arginine residues of proteins is catalyzed by protein arginine methyltransferases (PRMTs) that form monomethylarginine (MMA), asymmetric (ADMA) and symmetric dimethylarginines (SDMA). Although we previously demonstrated that the generation of ADMA residues in whole proteins is driven by PRMT-1 in Caenorhabditis elegans, much less is known about MMA and SDMA in vivo. In this study, we measured the amounts of different methylarginines in whole protein extracts made from wild-type (N2) C. elegans and from prmt-1 and prmt-5 null mutants using liquid chromatography-tandem mass spectrometry. Interestingly, we found that the amounts of MMA and SDMA are about fourfold higher than those of ADMA in N2 protein lysates using acid hydrolysis. We were unable to detect SDMA residues in the prmt-5 null mutant. In comparison with N2, an increase in SDMA and decrease in MMA were observed in prmt-1 mutant worms with no ADMA, but ADMA and MMA levels were unchanged in prmt-5 mutant worms. These results suggest that PRMT-1 contributes, at least in part, to MMA production, but that PRMT-5 catalyzes the symmetric dimethylation of substrates containing MMA residues in vivo.

Hydralazine is involved in tele-methylhistamine metabolism by inhibiting monoamine oxidase B in pregnancy-associated hypertensive mice

Hypertensive disorders of pregnancy globally affect 6-8% of gestation and remain a major cause of both foetal and maternal morbidity and mortality. However, the antihypertensive medications for the patients of this disease are strictly limited due to the teratogenic potentials. Here, we found that tele-methylhistamine (tMH) increased in response to the administration of hydralazine (Hdz), a vasodilative agent, in the pregnancy-associated hypertensive (PAH) mice. Hdz abrogated the degradation of tMH catalyzed by monoamine oxidase B (MAO-B) in vitro. These results suggested that Hdz inhibited the MAO-B activity and consequently tMH increased in the maternal circulation of PAH mice.

Severe Hypomyelination and Developmental Defects Are Caused in Mice Lacking Protein Arginine Methyltransferase 1 (PRMT1) in the Central Nervous System

Protein arginine methyltransferase 1 (PRMT1) is involved in cell proliferation, DNA damage response, and transcriptional regulation. Although PRMT1 is extensively expressed in the CNS at embryonic and perinatal stages, the physiological role of PRMT1 has been poorly understood. Here, to investigate the primary function of PRMT1 in the CNS, we generated CNS-specific PRMT1 knock-out mice by the Cre-loxP system. These mice exhibited postnatal growth retardation with tremors, and most of them died within 2 weeks after birth. Brain histological analyses revealed prominent cell reduction in the white matter tracts of the mutant mice. Furthermore, ultrastructural analysis demonstrated that myelin sheath was almost completely ablated in the CNS of these animals. In agreement with hypomyelination, we also observed that most major myelin proteins including myelin basic protein (MBP), 2',3'-cyclic-nucleotide 3'-phosphodiesterase (CNPase), and myelin-associated glycoprotein (MAG) were dramatically decreased, although neuronal and astrocytic markers were preserved in the brain of CNS-specific PRMT1 knock-out mice. These animals had a reduced number of OLIG2(+) oligodendrocyte lineage cells in the white matter. We found that expressions of transcription factors essential for oligodendrocyte specification and further maturation were significantly suppressed in the brain of the mutant mice. Our findings provide evidence that PRMT1 is required for CNS development, especially for oligodendrocyte maturation processes.

[Detection of apolipoproteins E5 and E7 by a widely used commercial ApoE IFE kit--evidence provided by genotyping]

The purpose of this study is to examine a possibility to detect apolipoprotein (apo) E5 and E7 isoproteins with a commercial kit widely used (Phenotyping Apo E IFE System, Jokoh Co. LTD., Tokyo) and to clarify the frequency of the rare alleles in Central Japan. A total of 1,445 subjects living in Central Japan (1,030 hemodialysis patients and 415 apparently healthy individuals) was phenotyped for apo E isoproteins with the kit using isoelectric focusing with immunoblotting. In 23 subjects, unique apo E4 isoproteins, which migrate more basically than apo E4 isoprotein, were found. These unique isoproteins were proved to be apo E5 or E7 isoproteins by PCR with restriction fragment length polymorphism and with amplification refractory mutation systems, respectively. No significant differences in the frequencies of apo E5 or apo E7 alleles were observed between healthy individuals and hemodialysis patients (0.011 vs. 0.018, NS). The frequencies of apo E5 and E7 alleles were 0.001 and 0.005, respectively, in healthy individuals, and 0.003 and 0.005, respectively, in hemodialysis patients. These data in Central Japan were consistent with those in Western Japan (Matsunaga, et al, Clin Genet, 1995). These results indicate that the commercial kit is applicable to detect the rare alleles, apo E5 and E7 alleles and that the frequencies of the rare alleles in Central Japan are similar to those in Western Japan.

[Relapsing polychondritis: a case with respiratory failure]

A 48-year-old woman was admitted to our hospital with respiratory failure (Hugh-Jones IV-V). She was diagnosed as relapsing polychondritis 6 years ago. Her respiratory failure was due to pharyngial stenosis, deformity and inflammation of a trachea and lobar bronchus, and bronchial collapse. Her tracheobronchochondritis was managed by 500-700 mg/day of hydrocortisone and 50 mg/day of cyclophosphamide. Laboratory examination revealed only slight elevation of CRP and no elevation of anti-type II collagen antibody, although these parameters were very high on her first admission when she had severe polyarthritis, polychondritis of nose and auricles. Bronchoscopic findings were compatible with tracheobronchomalacia since pharyngial stenosis due to inflammatory pharyngitis and bronchial collapse due to tracheobronchochondritis were shown without lung parenchymal damage. We referred to the literature on tracheobronchomalacia which was associated by the varieties of respiratory and rheumatic diseases.

The effect of 17 beta-estradiol treatment on the mass and the turnover of bone in ovariectomized rats taking a mild dose of thyroxin

We performed the dosing experiment to establish whether estrogen administration has any beneficial effects on the mass and the turnover of bone in ovariectomized rats taking a mild dose of thyroxin. Thirty-five Wistar rats, 28 weeks of age, received ovariectomies (OVX) or sham operations and were divided into five groups. Group 1 was the sham group, Groups 2-5 were ovariectomized. Group 2 was the OVX-control, Group 3 treated with thyroxin 30 micrograms/kg/day (T4), Group 4, 17 beta-estradiol 0.3 mg/kg/week (E2), and Group 5, the combination of T4 and E2. The duration of the experiment was 12 weeks. At the end of the experiment, serum chemistries were measured. Bone minerals in the femur were determined with single photon absorptiometry and bone turnover was assessed histomorphometrically. Alkaline-phosphatase increased in Group 3 (OVX-T4), but it reduced in Groups 4 (OVX-E2) and 5 (OVX-T4 + E2). Bone minerals decreased in Groups 2 (OVX) and 3. In Group 4, it was preserved at the same level as in Group 1. Group 5 showed a significant increase of bone mass compared with Group 1. Eroded surface and osteoid surface increased in Groups 2 and 3 and they were reduced in Groups 4 and 5. Bone volume and mineral apposition rate were at a maximum in Group 5. This study demonstrated that 17 beta-estradiol was capable of preventing the bone mass decrease by regulating the turnover in ovariectomized rats taking a mild dose of thyroxin. Osteoblast function appeared to be stimulated in combination with 17 beta-estradiol and thyroxin.