An Arabidopsis PTH2 Gene Is Responsible for Gravity Resistance Supporting Plant Growth under Different Gravity Conditions.

Terrestrial plants respond to and resist gravitational force. The response is termed "gravity resistance", and centrifugal hypergravity conditions are efficient for investigating its nature and mechanism. A functional screening of Arabidopsis T-DNA insertion lines for the suppression rate of elongation growth of hypocotyls under hypergravity conditions was performed in this study to identify the genes required for gravity resistance. As a result, we identified PEPTIDYL-tRNA HYDROLASE II (PTH2). In the wild type, elongation growth was suppressed by hypergravity, but this did not happen in the pth2 mutant. Lateral growth, dynamics of cortical microtubules, mechanical properties of cell walls, or cell wall thickness were also not affected by hypergravity in the pth2 mutant. In other words, the pth2 mutant did not show any significant hypergravity responses. However, the gravitropic curvature of hypocotyls of the pth2 mutant was almost equal to that of the wild type, indicating that the PTH2 gene is not required for gravitropism. It is suggested by these results that PTH2 is responsible for the critical processes of gravity resistance in Arabidopsis hypocotyls.

Plan comparison of prostate stereotactic radiotherapy in spacer implant patients.

In prostate stereotactic body radiation therapy (SBRT), hydrogel spacers are increasingly used. This study aimed to perform a dosimetry comparison of treatment plans using CyberKnife (CK), commonly used for prostate SBRT, Helical TomoTherapy (HT), and TrueBeam (TB) in patients with hydrogel spacer implantations. The data of 20 patients who received hydrogel spacer implantation for prostate SBRT were retrospectively analyzed. The prescription dose was 36.25 Gy in five fractions to 95% of the planning target volume (PTV; D95). The conformity index (CI), gradient index (GI), homogeneity index (HI), and dose-volume histogram (DVH) were analyzed for the three modalities, using the same PTV margins. The monitor unit (MU) and the beam-on-time (BOT) values were subsequently compared. The CI of TB (0.93 ± 0.02) was significantly superior to those of CK (0.82 ± 0.03, p < 0.01) and HT (0.86 ± 0.03, p < 0.01). Similarly, the GI value of TB (3.59 ± 0.12) was significantly better than those of CK (4.31 ± 0.43, p < 0.01) and HT (4.52 ± 0.24, p < 0.01). The median doses to the bladder did not differ between the CK and TB (V18.1 Gy: 16.5% ± 4.5% vs. 15.8% ± 4.4%, p = 1.00), but were significantly higher for HT (V18.1 Gy: 33.2% ± 7.3%, p < 0.01 vs. CK, p < 0.01 vs. TB). The median rectal dose was significantly lower for TB (V18.1 Gy: 5.6% ± 4.5%) than for CK (V18.1 Gy: 11.2% ± 6.7%, p < 0.01) and HT (20.2% ± 8.3%, p < 0.01). TB had the shortest BOT (2.6 min; CK: 17.4 min, HT: 6.9 min). TB could create treatment plans dosimetrically comparable to those of CK when using the same margins, in patients with hydrogel spacers.

Difficulty in distinguishing radiation-induced prostate sarcoma from radiation mucositis in a patient with persistent urinary retention and hematuria after prostate cancer radiotherapy.

Urinary retention and hematuria owing to radiation-induced mucositis are occasional late adverse events in patients with prostate cancer. Moreover, radiation-induced secondary malignancies are late adverse events, although they are extremely rare. Herein, we describe a case of radiation-induced secondary malignancy of the prostate that was initially difficult to distinguish from radiation mucositis. A 74-year-old man with prostate cancer underwent brachytherapy and external beam radiotherapy 9 years ago. Twenty-eight months after irradiation, he presented with urinary retention and hematuria owing to radiation mucositis and underwent transurethral resection of the prostate. At 89 months after irradiation, the patient again showed urinary retention and hematuria. The cause of urinary retention and hematuria could not be identified on cystoscopy. Despite receiving medications, the patient's symptoms did not improve. Therefore, transurethral fulguration was performed, and prostate biopsy revealed spindle cell sarcoma. A diagnosis of radiation-induced undifferentiated pleomorphic/spindle cell sarcoma was made, and the patient underwent total cystectomy and construction of the ileal conduit. Two weeks after the surgery, computed tomography revealed peritoneal dissemination. The patient died 5 weeks after the surgery. The case findings indicate that clinicians should consider the possibility of radiation-induced secondary malignancy; moreover, thorough pathological examination of the prostate with CT and MRI is important to distinguish RISM from radiation mucositis even if no tumors are found on cystoscopy.

Endogenous Endophthalmitis successfully treated with Intravitreal Povidone-iodine injection: a case report.

BACKGROUND: The usefulness of povidone-iodine as an alternative to antimicrobial agents, for endophthalmitis, has recently been documented. We report a case of endogenous endophthalmitis successfully treated with intravitreal injection of povidone-iodine. CASE PRESENTATION: An 88-year-old woman underwent small bowel bypass surgery for postoperative ileus following rectal cancer resection. She developed a fever during total parenteral nutrition and was diagnosed with gram-positive cocci bacteremia of central venous catheter origin. The patient was referred to our department with chief complaints of ocular pain, hyperemia and decreased vision in the right eye, which had manifested during the febrile period. The initial examination revealed the visual acuity in her right eye to be finger counting and that in her left eye 0.2. The right eye showed a severe inflammatory reaction in the anterior chamber, fibrin deposition, and hypopyon. The fundus was difficult to visualize. Endogenous endophthalmitis due to bacteria was diagnosed. Surgical treatment was judged to be difficult based on the patient's poor general condition and mental status, and intravitreal injection of 0.1 ml of 1.25% povidone-iodine was performed on the same day. The inflammation rapidly diminished, and the hypopyon had disappeared 4 days after treatment. The fundus became visible 7 days after treatment and there was no recurrence of endophthalmitis findings. The visual acuity in her right eye recovered to that in the left eye (0.2). CONCLUSION: Intravitreal injection of povidone-iodine is potentially useful and effective as an alternative treatment of antibiotics for endogenous endophthalmitis patients, especially in whom surgical therapy is difficult.

MCA1 and MCA2 Are Involved in the Response to Hypergravity in Arabidopsis Hypocotyls.

Plants respond to and resist gravitational acceleration, but the mechanism of signal perception in the response is unknown. We studied the role of MCA (mid1-complementing activity) proteins in gravity perception by analyzing the expression of the MCA1 and MCA2 genes, and the growth of hypocotyls of mca mutants, under hypergravity conditions in the dark. An MCA1 promoter::GUS fusion reporter gene construct (MCA1p::GUS) and MCA2p::GUS were expressed almost universally in etiolated seedlings. Under hypergravity conditions, the expression levels of both genes increased compared with that under the 1 g condition, and remained higher, especially in the basal supporting region. On the other hand, mca-null and MCA-overexpressing seedlings showed normal growth under the 1 g condition. Hypergravity suppressed elongation growth of hypocotyls, but this effect was reduced in hypocotyls of mca-null mutants compared with the wild type. In contrast, MCA-overexpressing seedlings were hypersensitive to increased gravity; suppression of elongation growth was detected at a lower gravity level than that in the wild type. These results suggest that MCAs are involved in the perception of gravity signals in plants, and may be responsible for resistance to hypergravity.

Kynurenine plays an immunosuppressive role in 2,4,6-trinitrobenzene sulfate-induced colitis in mice.

BACKGROUND: Inflammatory bowel disease, such as Crohn's disease and ulcerative colitis, is characterized by chronic intestinal inflammation leading to intestinal mucosal damage. Inflammatory bowel disease causes dysregulation of mucosal T cell responses, especially the responses of CD4+ T cells. Previously, we demonstrated that indoleamine-2,3-dioxygenase plays an immunosuppressive role in 2,4,6-trinitrobenzene sulfate (TNBS)-induced colitis. Although indoleamine-2,3-dioxygenase exerts immunosuppressive effects by altering the local concentration of tryptophan (Trp) and immunomodulatory Trp metabolites, the specific changes in immune regulation during colitis caused by Trp metabolites and its related enzymes remain unclear. AIM: To investigate role of kynurenine 3-monooxygenase (KMO) in TNBS-induced colitis and involvement of Trp metabolites in maintenance of intestinal homeostasis. METHODS: Colitis was induced in eight-week-old male KMO+/+ or KMO-/- mice of C57BL/6N background using TNBS. Three days later, the colon was used for hematoxylin-eosin staining for histological grading, immunohistochemical or immunofluorescence staining for KMO, cytokines, and immune cells. Inflammatory and anti-inflammatory cytokines were measured using quantitative RT-PCR, and kynurenine (Kyn) pathway metabolites were measured by high-performance liquid chromatography. The cell proportions of colonic lamina propria and mesenteric lymph nodes were analyzed by flow cytometry. RESULTS: KMO expression levels in the colonic mononuclear phagocytes, including dendritic cells and macrophages increased upon TNBS induction. Notably, KMO deficiency reduced TNBS-induced colitis, resulting in an increased frequency of Foxp3+ regulatory T cells and increased mRNA and protein levels of anti-inflammatory cytokines, including transforming growth factor-ß and interleukin-10. CONCLUSION: Absence of KMO reduced TNBS-induced colitis via generation of Foxp3+ regulatory T cells by producing Kyn. Thus, Kyn may play a therapeutic role in colon protection during colitis.

Anterior Lens Capsule Transplantation for Acquired Optic Disc Pit Maculopathy.

A patient with acquired optic disc pit (ODP) maculopathy underwent vitrectomy with anterior capsule transplantation to the ODP and gas tamponade. Structural changes were evaluated by enhanced depth imaging optical coherence (OCT) tomography. During vitrectomy, the eye was confirmed to have preexisting posterior vitreous detachment. Postoperative OCT showed complete closure of the optic pit resulting in rapid absorption of subretinal fluid. The authors' observations suggest that the anterior capsule is a useful material for achieving optic pit closure. To the authors' knowledge, this is the first report describing application of the anterior capsule to the treatment of ODP maculopathy. [Ophthalmic Surg Lasers Imaging Retina. 2019;50:649-652.].

Prospective study of vitrectomy for epiretinal membranes in patients with good best-corrected visual acuity.

BACKGROUND: To evaluate the efficacy of epiretinal membrane removal in patients with good best-corrected visual acuity (BCVA) for improving visual function and quality of life (QOL). METHODS: This prospective case study compared 37 subjects with preoperative BCVA ≦ 0.046 logMAR (Good group) to 35 patients with 0.10-0.52 logMAR (Moderate group) at 3 and 6 months. Linear mixed-effect models were used for statistical analysis. The primary outcome was the horizontal metamorphopsia score (MH) at 6 months postoperatively (post-6 M), while secondary outcomes were postoperative BCVA, vertical metamorphopsia score (MV), aniseikonia, stereopsis and central foveal thickness. In the Good group, QOL was assessed using the National Eye Institute Visual Functioning Questionnaire-25 (NEI VFQ-25) at 6 and 12 months. RESULTS: MH was significantly improved at post-3 M and post-6 M in the both groups but there were no significant differences between the two groups. MV showed no improvement at the final observation in either group. LogMAR BCVA was significantly improved at post-6 M in the Good group, which had significantly better vision than the Moderate group. Preoperative vertical and horizontal aniseikonia scores remained unchanged in the Good group at post-6 M but worsened in the Moderate group. The NEI VFQ-25 score improved in the Good group, reflecting improved general health, general vision, and mental health. CONCLUSIONS: Early epiretinal surgery for patients with BCVA ≦ 0.046 logMAR was effective for improvement of HM, BCVA, and QOL and prevented worsening of aniseikonia. TRIAL REGISTRATION: UMIN000021220 . Registered 10 September 2015. UMIN Clinical Trials Registry.

No increase in incidence of post-intravitreal injection endophthalmitis without topical antibiotics: a prospective study.

PURPOSE: In our previous report, intravitreal injection using 0.25% povidone-iodine to irrigate the conjunctival sac together with pre- and post-injection topical antibiotics achieved an incidence of post-injection endophthalmitis significantly lower than other reports. In this study, we examined whether similarly low incidence is achieved without using any topical antibiotics. STUDY DESIGN: Prospective cohort study. METHODS: We evaluated intravitreal injections of anti-vascular endothelial growth factor agents conducted by vitreoretinal specialists at the outpatient injection room of a single university hospital. This study had two protocols. First stage: We performed more than 3000 injections with pre-injection but without post-injection topical antibiotics. Final stage: After confirming no case of endophthalmitis in the first stage, we performed more than 12,500 injections without either pre- or post-injection topical antibiotics. In both protocols, we used 0.25% povidone-iodine to sterilize the conjunctival sac both before and after injection. RESULTS: First stage was performed between April 2015 and January 2016. No case of suspected or proven infectious endophthalmitis occurred in 6039 injections [95% confidence interval (CI) 0-0.000497%]. Final stage was performed between February 2016 and November 2017. No case of suspected or proven infectious endophthalmitis occurred in 12,523 injections (95% CI 0-0.00024%). This result was comparable to our previous study using both pre- and post-injection topical antibiotics (0/15,144 injections, 95% CI 0-0.000198%). CONCLUSION: Using conjunctival sac irrigation with 0.25% povidone-iodine before and after intravitreal injection, the incidence of endophthalmitis remains low even when the use of pre- or post-injection topical antibiotics is discontinued.

Long-Term Outcomes of Endovascular Stenting for Blunt Renal Artery Injuries with Stenosis: A Report of Five Consecutive Cases.

BACKGROUND: Renal artery stenting is performed for renal artery injuries to preserve renal function and prevent renovascular hypertension. However, its indications are controversial and its long-term prognosis remains unknown. Here, we evaluate the characteristics and long-term outcomes of renal artery stenting for blunt renal artery injuries at our institution. METHODS: We retrospectively reviewed patients with blunt renal artery injuries who had been treated with stenting over a 12-year period at our institution. Five patients (three men and two women) were included. RESULTS: Trauma resulted from falls in three patients and motor vehicle accidents in two. All patients had experienced multiple injuries (median injury severity score, 24 [range, 16-48]; median revised trauma score, 5.9672 [4.0936-7.8408]; and median probability of survival, 0.689 [0.533-0.980]). All renal artery injuries involved stenosis because of traumatic arterial dissection or intimal tear; no cases of total occlusion were observed. No complications due to the intervention itself were observed. Although two patients developed reversible acute renal failure, none required long-term hemodialysis. One patient with renovascular hypertension was treated with antihypertensive agents for a month and subsequently became normotensive without further medication. All patients underwent postoperative computed tomography, which revealed no stent occlusion or renal atrophy. Renal scintigraphy for three patients demonstrated preserved differential renal function. All five patients survived. CONCLUSIONS: Renal artery stenting for hemodynamically stable blunt renal artery injuries with stenosis is suggested to be safe and helps in avoiding long-term hemodialysis and renovascular hypertension.

Development of a Potent Protein Degrader against Oncogenic BCR-ABL Protein.

Chromosomal translocation occurs in some cancer cells, resulting in the expression of aberrant oncogenic fusion proteins that include BCR-ABL in chronic myelogenous leukemia (CML). Inhibitors of ABL tyrosine kinase, such as imatinib and dasatinib, exhibit remarkable therapeutic effects, although emergence of drug resistance hampers the therapy during long-term treatment. An alternative approach to treat CML is to downregulate expression of the BCR-ABL protein. Recently, we have devised a protein knockdown system by hybrid molecules named Specific and Nongenetic inhibitor of apoptosis protein [IAP]-dependent Protein Erasers (SNIPER). This system is designed to induce IAP-mediated ubiquitylation and proteasomal degradation of target proteins. In this review, we describe the development of SNIPER against BCR-ABL, and discuss the features and prospect for treatment of CML.

Intravitreal Injection of 1.25% Povidone Iodine Followed by Vitrectomy Using 0.025% Povidone Iodine Irrigation for Treating Endophthalmitis.

PURPOSE: To investigate the safety and effectiveness of intravitreal injection (IVI) of 1.25% povidone iodine (PI) followed by vitrectomy using 0.025% PI irrigation for treating endophthalmitis. METHODS: Prospective case series study. Nine eyes of 8 patients with postoperative or endogenous endophthalmitis treated at the Nihon University Hospital between April 2015 and October 2017 were studied. First, IVI of 0.1 mL/1.25%PI was conducted, followed by anterior chamber irrigation and vitrectomy using 0.025%PI irrigation solution. Corneal epithelial damage, anterior chamber inflammation, and vitreous inflammation were assessed and fundus examinations were performed, using a slit-lamp microscope and indirect ophthalmoscopy. A specular microscope, Goldmann perimetry, and electroretinography (ERG) were also used. RESULTS: In all but case 7, endophthalmitis resolved rapidly and good visual acuity was maintained. No adverse events were noted. Furthermore, the perioperative ERG showed improvements in the oscillatory potentials amplitudes on ERG and flicker ERG, as well as in the implicit time of the a-wave, suggesting functional recovery in the retinal outer and inner layers after therapy. CONCLUSIONS: IVI of PI followed by vitrectomy was thought to be a safe and effective treatment for endophthalmitis. TRANSLATIONAL RELEVANCE: We succeeded in proving the clinical safety of IVI of PI followed by vitrectomy with PI irrigation as well as previous experimental reports. PI is available in world widely, therefore this method will be optimal treatment for endophthalmitis.

Different Degradation Mechanisms of Inhibitor of Apoptosis Proteins (IAPs) by the Specific and Nongenetic IAP-Dependent Protein Eraser (SNIPER).

Targeted protein degradation by small molecules is an emerging modality with significant potential for drug discovery. We previously developed chimeric molecules, termed specific and non-genetic inhibitor of apoptosis protein (IAP)-dependent protein erasers (SNIPERs), which induce the ubiquitylation and proteasomal degradation of target proteins. This degradation is mediated by the IAPs; the target proteins include bromodomain-containing protein 4 (BRD4), an epigenetic regulator protein. The SNIPER that degrades this particular protein, SNIPER(BRD)-1, consists of an IAP antagonist LCL-161 derivative and a bromodomain and extra-terminal (BET) inhibitor, (+)-JQ-1. SNIPER(BRD)-1 also degrades a cellular inhibitor of apoptosis protein 1 (cIAP1) and an X-linked inhibitor of apoptosis protein (XIAP), the mechanisms of which are not well understood. Here, we show that the degradation of cIAP1 and XIAP by SNIPER(BRD)-1 is induced via different mechanisms. Using a chemical biology-based approach, we developed two inactive SNIPERs, SNIPER(BRD)-3 and SNIPER(BRD)-4, incapable of degrading BRD4. SNIPER(BRD)-3 contained an N-methylated LCL-161 derivative as the IAP ligand, which prevented it from binding IAPs, and resulted in the abrogated degradation of cIAP1, XIAP, and BRD4. SNIPER(BRD)-4, however, incorporated the enantiomer (-)-JQ-1 which was incapable of binding BRD4; this SNIPER degraded cIAP1 but lost the ability to degrade XIAP and BRD4. Furthermore, a mixture of the ligands, (+)-JQ-1 and LCL-161, induced the degradation of cIAP1, but not XIAP and BRD4. These results indicate that cIAP1 degradation is triggered by the binding of the IAP antagonist module to induce autoubiquitylation of cIAP1, whereas a ternary complex formation is required for the SNIPER-induced degradation of XIAP and BRD4.

Design and synthesis of cell-permeable fluorescent nitrilotriacetic acid derivatives.

Fluorescence labeling of the target molecules using a small molecule-based probe is superior than a method using genetically expressed green fluorescence protein (GFP) in terms of convenience in its preparation and functionalization. Fluorophore-nitrilotriacetic acid (NTA) conjugates with several ester protecting groups were synthesized and evaluated for their cell membrane permeability by fluorescence microscopy analysis. One of the derivatives, acetoxymethyl (AM)-protected NTA conjugate is hydrolyzed, resulting in intracellular accumulation, thus providing localized fluorescence intensity in cells. This modification is expected as an effective method for converting a non-cell membrane permeable NTA-BODIPY conjugates to a cell membrane permeable derivatives.

Pharmacological difference between degrader and inhibitor against oncogenic BCR-ABL kinase.

Chronic myelogenous leukemia (CML) is characterized by the oncogenic fusion protein, BCR-ABL protein kinase, against which clinically useful inhibitors have been developed. An alternative approach to treat CML is to degrade the BCR-ABL protein. Recently, potent degraders against BCR-ABL have been developed by conjugating dasatinib to ligands for E3 ubiquitin ligases. Since the degraders contain the dasatinib moiety, they also inhibit BCR-ABL kinase activity, which complicates our understanding of the impact of BCR-ABL degradation by degraders in CML growth inhibition. To address this issue, we chose DAS-IAP, as a potent BCR-ABL degrader, and developed a structurally related inactive degrader, DAS-meIAP, which inhibits kinase activity but does not degrade the BCR-ABL protein. DAS-IAP showed slightly weaker activity than DAS-meIAP in inhibiting cell growth when CML cells were treated for 48 h. However, DAS-IAP showed sustained growth inhibition even when the drug was removed after short-term treatment, whereas CML cell growth rapidly resumed following removal of DAS-meIAP and dasatinib. Consistently, suppression of BCR-ABL levels and downstream kinase signaling were maintained after DAS-IAP removal, whereas kinase signaling rapidly recovered following removal of DAS-meIAP and dasatinib. These results indicate that BCR-ABL degrader shows more sustained inhibition of CML cell growth than ABL kinase inhibitor.

Acquired Resistance to Shiga Toxin-Induced Apoptosis by Loss of CD77 Expression in Human Myelogenous Leukemia Cell Line, THP-1.

Shiga toxin (Stx) is a main virulence factor of Enterohemorrhagic Escherichia coli (EHEC) that causes diarrhea and hemorrhagic colitis and occasionally fatal systemic complications. Stx induces rapid apoptotic cell death in some cells, such as human myelogenous leukemia THP-1 cells expressing CD77, a receptor for Stx internalization, and the induction of apoptotic cell death is thought to be crucial for the fatal systemic complications. Therefore, in order to suppress the fatal toxicity, it is important to understand the mechanism how cells can escape from apoptotic cell death in the presence of Stx. In this study, we isolated resistant clones to Stx-induced apoptosis from highly sensitive THP-1 cells by continuous exposure with lethal dose of Stx. All of the ten resistant clones lost the expression of CD77 as a consequence of the reduction in CD77 synthase mRNA expression. These results suggest that downregulation of CD77 or CD77 synthase expression could be a novel approach to suppress the fatal toxicity of Stx in EHEC infected patient.

Derivatization of inhibitor of apoptosis protein (IAP) ligands yields improved inducers of estrogen receptor α degradation.

Aberrant expression of proteins often underlies many diseases, including cancer. A recently developed approach in drug development is small molecule-mediated, selective degradation of dysregulated proteins. We have devised a protein-knockdown system that utilizes chimeric molecules termed specific and nongenetic IAP-dependent protein erasers (SNIPERs) to induce ubiquitylation and proteasomal degradation of various target proteins. SNIPER(ER)-87 consists of an inhibitor of apoptosis protein (IAP) ligand LCL161 derivative that is conjugated to the estrogen receptor α (ERα) ligand 4-hydroxytamoxifen by a PEG linker, and we have previously reported that this SNIPER efficiently degrades the ERα protein. Here, we report that derivatization of the IAP ligand module yields SNIPER(ER)s with superior protein-knockdown activity. These improved SNIPER(ER)s exhibited higher binding affinities to IAPs and induced more potent degradation of ERα than does SNIPER(ER)-87. Further, they induced simultaneous degradation of cellular inhibitor of apoptosis protein 1 (cIAP1) and delayed degradation of X-linked IAP (XIAP). Notably, these reengineered SNIPER(ER)s efficiently induced apoptosis in MCF-7 human breast cancer cells that require IAPs for continued cellular survival. We found that one of these molecules, SNIPER(ER)-110, inhibits the growth of MCF-7 tumor xenografts in mice more potently than the previously characterized SNIPER(ER)-87. Mechanistic analysis revealed that our novel SNIPER(ER)s preferentially recruit XIAP, rather than cIAP1, to degrade ERα. Our results suggest that derivatized IAP ligands could facilitate further development of SNIPERs with potent protein-knockdown and cytocidal activities against cancer cells requiring IAPs for survival.

Development of Protein Degradation Inducers of Androgen Receptor by Conjugation of Androgen Receptor Ligands and Inhibitor of Apoptosis Protein Ligands.

Targeted protein degradation using small molecules is a novel strategy for drug development. We have developed hybrid molecules named specific and nongenetic inhibitor of apoptosis protein [IAP]-dependent protein erasers (SNIPERs) that recruit IAP ubiquitin ligases to degrade target proteins. Here, we show novel SNIPERs capable of inducing proteasomal degradation of the androgen receptor (AR). Through derivatization of the SNIPER(AR) molecule at the AR ligand and IAP ligand and linker, we developed 42a (SNIPER(AR)-51), which shows effective protein knockdown activity against AR. Consistent with the degradation of the AR protein, 42a inhibits AR-mediated gene expression and proliferation of androgen-dependent prostate cancer cells. In addition, 42a efficiently induces caspase activation and apoptosis in prostate cancer cells, which was not observed in the cells treated with AR antagonists. These results suggest that SNIPER(AR)s could be leads for an anticancer drug against prostate cancers that exhibit AR-dependent proliferation.

Development of a Small Hybrid Molecule That Mediates Degradation of His-Tag Fused Proteins.

In recent years, the induction of target-protein degradation via the ubiquitin-proteasome system (UPS) mediated by small molecules has attracted attention, and this approach has applications in pharmaceutical development. However, this technique requires a ligand for the target protein that can be incorporated into tailor-made molecules, and there are many proteins for which such ligands have not been found. In this study, we developed a protein-knockdown method that recognizes a His-tag fused to a protein of interest. This strategy theoretically allows comprehensive targeting of proteins of interest by a particular molecule recognizing the tag. As expected, our hybrid molecule 10 [SNIPER(CH6)] efficiently degraded His-tagged CRABP-II and Smad2 in cells. This system provides an easy method to determine the susceptibility of proteins of interest to UPS-mediated degradation. Furthermore, we hope that this method will become an efficient tool to analyze the function of the UPS.