Intrinsic signaling pathways modulate targeted protein degradation.

Targeted protein degradation is a groundbreaking modality in drug discovery; however, the regulatory mechanisms are still not fully understood. Here, we identify cellular signaling pathways that modulate the targeted degradation of the anticancer target BRD4 and related neosubstrates BRD2/3 and CDK9 induced by CRL2VHL- or CRL4CRBN -based PROTACs. The chemicals identified as degradation enhancers include inhibitors of cellular signaling pathways such as poly-ADP ribosylation (PARG inhibitor PDD00017273), unfolded protein response (PERK inhibitor GSK2606414), and protein stabilization (HSP90 inhibitor luminespib). Mechanistically, PARG inhibition promotes TRIP12-mediated K29/K48-linked branched ubiquitylation of BRD4 by facilitating chromatin dissociation of BRD4 and formation of the BRD4-PROTAC-CRL2VHL ternary complex; by contrast, HSP90 inhibition promotes BRD4 degradation after the ubiquitylation step. Consequently, these signal inhibitors sensitize cells to the PROTAC-induced apoptosis. These results suggest that various cell-intrinsic signaling pathways spontaneously counteract chemically induced target degradation at multiple steps, which could be liberated by specific inhibitors.

Predictive factors for response to neoadjuvant chemotherapy: inflammatory and immune markers in triple-negative breast cancer.

BACKGROUND: Tumor-infiltrating lymphocytes (TILs) predict response to neoadjuvant chemotherapy (NAC) in triple-negative breast cancer (TNBC) patients. However, the TIL level can be determined at a few facilities. By contrast, neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) are easily and objectively determined from the results of full blood counts. We conducted a retrospective study to investigate whether TILs, NLR, and PLR predict NAC efficacy and whether NLR and PLR could be surrogate markers for TILs in TNBC. METHODS: Of the 266 patients diagnosed with TNBC between 2013 and 2019, 66 who underwent radical surgery after sequential administration of anthracycline and taxane as NAC were included in the study. TILs, NLR, and PLR were evaluated as predictors of pathologic complete response (pCR) using cutoff values determined from receiver operating characteristic curves. RESULTS: The cutoff values of TILs, NLR, and PLR were 20%, 2.6, and 180, respectively. High TIL level was associated with low NLR (P = 0.01) and low PLR (P = 0.01). High TIL level (odds ratio [OR] 4.28 [95% CI 1.40-13.1]; P = 0.01), low NLR (OR 5.51 [95% CI 1.60-18.9]; P = 0.01), and low PLR (OR 3.29 [95% CI 1.13-9.57]; P = 0.03) were associated with pCR. Low NLR predicted pCR independently (OR 6.59 [95% CI 1.45-30.0]; P = 0.01). CONCLUSIONS: TILs, NLR, and PLR predicted NAC efficacy against TNBC. TIL level was associated with NLR and PLR. NLR was an independent predictive factor and may be a useful surrogate marker for TILs when predicting pCR.

cIAP1-based degraders induce degradation via branched ubiquitin architectures.

Targeted protein degradation through chemical hijacking of E3 ubiquitin ligases is an emerging concept in precision medicine. The ubiquitin code is a critical determinant of the fate of substrates. Although two E3s, CRL2VHL and CRL4CRBN, frequently assemble with proteolysis-targeting chimeras (PROTACs) to attach lysine-48 (K48)-linked ubiquitin chains, the diversity of the ubiquitin code used for chemically induced degradation is largely unknown. Here we show that the efficacy of cIAP1-targeting degraders depends on the K63-specific E2 enzyme UBE2N. UBE2N promotes degradation of cIAP1 induced by cIAP1 ligands and subsequent cancer cell apoptosis. Mechanistically, UBE2N-catalyzed K63-linked ubiquitin chains facilitate assembly of highly complex K48/K63 and K11/K48 branched ubiquitin chains, thereby recruiting p97/VCP, UCH37 and the proteasome. Degradation of neo-substrates directed by cIAP1-recruiting PROTACs also depends on UBE2N. These results reveal an unexpected role for K63-linked ubiquitin chains and UBE2N in degrader-induced proteasomal degradation and demonstrate the diversity of the ubiquitin code used for chemical hijacking.

[A Case of Chronic Expanding Hematoma of the Lower Abdomen after Reconstruction of Deep Inferior Epigastric Perforator Flap for Breast Cancer].

A 49-year-old woman who had surgery for left breast cancer and subsequently underwent a two-stage deep inferior epigastric perforator(DIEP)flap reconstruction. One month postoperatively, she became aware of abdominal distention and visited a local hospital. CT scan revealed subcutaneous fluid accumulation with capsular formation in the lower abdomen. Imaging findings and physical examination showed no abdominal wall scar hernia. After multiple puncture aspirations, fluid accumulation was observed again, and the possibility of a chronic expanding hematoma was considered. Later, hematoma removal, including the capsules, was performed; pathological findings showed no evidence of malignancy. No fluid retention was observed postoperatively. In cases where imaging evaluation reveals hematoma formation with capsules, hematoma removal, including the capsules, should be performed to avert the possibility of a chronic expanding hematoma.

Side-To-Side Difference in Electromyographic Activity of Abdominal Muscles during Asymmetric Exercises.

A side-to-side difference in the muscle size of the rectus abdominis has been suggested to increase the strain injury risk. Attenuating the difference in size of the rectus abdominis may decrease the injury risk. To explore ways to highly activate one side of the rectus abdominis, we aimed to clarify the activity levels of both sides of the muscle during asymmetric abdominal exercises. Fifteen male sprinters performed the following five asymmetric exercises for the right and left sides: (i) sit-up twist, (ii) oblique leg raise, (iii) side bridge, (iv) side bridge roll out with the elbow, and (v) side bridge roll out with the foot. Side bridge roll out with the elbow and that with the foot were performed using a wheeled platform. During the exercises, electromyographic signals were recorded bilaterally from the upper, central, and lower portions of the rectus abdominis. We calculated the root mean square of electromyograms during the concentric and eccentric phases of the exercises and normalized to that during maximal voluntary contractions. In all portions of the rectus abdominis, the root mean squares of electromyograms were significantly higher in the moving side than in the non-moving side during the concentric and eccentric phases of the side bridge, the side bridge roll out with the elbow and that with the foot (all p < 0.01), but not in sit-up twist or oblique leg raise. The root mean squares of electromyograms of all portions of the rectus abdominis in the moving side were significantly higher in the side bridge roll out with the elbow and that with the foot than in the side bridge during both phases (all p < 0.01). The results suggest that the application of the wheeled platform to side bridge is useful to highly activate one side of the rectus abdominis.

Skeletal muscle loss during neoadjuvant chemotherapy predicts poor prognosis in patients with breast cancer.

BACKGROUND: The skeletal muscle index (SMI), which is calculated as the ratio of skeletal muscle area at the third lumbar vertebral level divided by height squared, has been considered a prognostic factor in patients with breast cancer. However, the prognostic impact of changes in SMI during treatment remains unclear. This study aimed to evaluate the influence of SMI changes in patients with breast cancer undergoing neoadjuvant chemotherapy (NAC). METHODS: We reviewed patients with breast cancer who underwent NAC and subsequent surgery for breast cancer between 2010 and 2017. The rate of SMI change during NAC was calculated, and the association between SMI changes and prognosis was retrospectively analyzed. RESULTS: In total, 141 patients were evaluated. 48 (34.0%), 53 (37.6%), and 40 (28.4%) patients exhibited increased (≥ 3%), maintained (- 3% <, < 3%), and decreased (- 3% ≥) SMI during NAC, respectively. The decreased SMI group showed significantly poorer disease-free survival than the maintained and increased SMI groups (hazard ratio [HR] 8.29, p <  0.001 for the decreased vs. increased SMI groups; HR 3.49, p <  0.001 for the decreased vs. maintained SMI groups). Moreover, decreased SMI was an independent risk factor for disease-free survival in multivariate analysis (HR 3.68, p <  0.01). CONCLUSIONS: Skeletal muscle loss during NAC predicts poor prognosis. Our results underscore the importance of monitoring and maintaining skeletal muscle mass during NAC.

Design, Synthesis, and Evaluation of Trivalent PROTACs Having a Functionalization Site with Controlled Orientation.

Trivalent PROTACs having a functionalization site with controlled orientation were designed, synthesized, and evaluated. Based on the X-ray structure of BRD protein degrader MZ1 (1) in complex with human VHL and BRD4BD2, we expected that the 1,2-disubstituted ethyl group near the JQ-1 moiety in MZ1 (1) could be replaced by a planar benzene tether as a platform for further functionalization. To test this hypothesis, we first designed six divalent MZ1 derivatives, 2a-c and 3a-c, by combining three variations of substitution patterns on the benzene ring (1,2-, 1,3-, and 1,4-substitution) and two variations in the number of ethylene glycol units (2 or 1). We then tested the synthesized compounds for the BRD4 degradation activity of each. As expected, we found that 1,2D-EG2-MZ1 (2a), an MZ1 derivative with 1,2-disubstituted benzene possessing two ethylene glycol units, had an activity profile similar to that of MZ1 (1). Based on the structure of 2a, we then synthesized and evaluated four isomeric trivalent MZ1 derivatives, 15a-15d, having a tert-butyl ester unit on the benzene ring as a handle for further functionalization. Among the four isomers, 1,2,5T-EG2-MZ1 (15c) retained a level of BRD4 depletion activity similar to that of 2a without inducing a measurable Hook effect, and its BRD4 depletion kinetics was the same as that of MZ1 (1). Other isomers were also shown to retain BRD4 depletion activity. Thus, the trivalent PROTACs we synthesized here may serve as efficient platforms for further applications.

Archival bone marrow smears are useful in targeted next-generation sequencing for diagnosing myeloid neoplasms.

Gene abnormalities, including mutations and fusions, are important determinants in the molecular diagnosis of myeloid neoplasms. The use of bone marrow (BM) smears as a source of DNA and RNA for next-generation sequencing (NGS) enables molecular diagnosis to be done with small amounts of bone marrow and is especially useful for patients without stocked cells, DNA or RNA. The present study aimed to analyze the quality of DNA and RNA derived from smear samples and the utility of NGS for diagnosing myeloid neoplasms. Targeted DNA sequencing using paired BM cells and smears yielded sequencing data of adequate quality for variant calling. The detected variants were analyzed using the bioinformatics approach to detect mutations reliably and increase sensitivity. Noise deriving from variants with extremely low variant allele frequency (VAF) was detected in smear sample data and removed by filtering. Consequently, various driver gene mutations were detected across a wide range of allele frequencies in patients with myeloid neoplasms. Moreover, targeted RNA sequencing successfully detected fusion genes using smear-derived, very low-quality RNA, even in a patient with a normal karyotype. These findings demonstrated that smear samples can be used for clinical molecular diagnosis with adequate noise-reduction methods even if the DNA and RNA quality is inferior.

Papillary thyroid microcarcinoma with lung metastases: a case report and review of the literature.

BACKGROUND: Distant metastasis from papillary thyroid microcarcinoma (PTMC) is rare. Here we report a case of PTMC with multiple lung metastases. CASE PRESENTATION: A 64-year-old man presented to our hospital with abdominal pain. Computed tomography incidentally revealed multiple lung nodules. The lung tumor was histologically diagnosed as metastasis of papillary thyroid carcinoma (PTC) by core needle biopsy via thoracoscopy. The patient was referred to our department for further examination. Neck ultrasonography revealed a 0.9 cm hypoechoic nodule in the right lobe of the thyroid gland, which was diagnosed as PTC by fine-needle aspiration cytology. Subsequently, total thyroidectomy was performed, followed by radioiodine therapy. Iodine-131 (131-I) scintigraphy showed a strong accumulation in the lung metastasis. The patient presented no evidence of progression of lung metastasis for 25 months after the operation. CONCLUSIONS: Lymph node metastasis or extraglandular extension has been reported in the few published cases of metastatic PTMC, including the present case, and the average age of these cases was 58.8 ± 12.0 years. Although active surveillance without surgical resection is expected to become a standard of care for PTMC, this case indicates that a subset of PTMC patients with risk factors may develop distant metastases. Hence, careful preoperative screening is required to avoid complications associated with completion thyroidectomy.

TRIP12 promotes small-molecule-induced degradation through K29/K48-branched ubiquitin chains.

Targeted protein degradation is an emerging therapeutic paradigm. Small-molecule degraders such as proteolysis-targeting chimeras (PROTACs) induce the degradation of neo-substrates by hijacking E3 ubiquitin ligases. Although ubiquitylation of endogenous substrates has been extensively studied, the mechanism underlying forced degradation of neo-substrates is less well understood. We found that the ubiquitin ligase TRIP12 promotes PROTAC-induced and CRL2VHL-mediated degradation of BRD4 but is dispensable for the degradation of the endogenous CRL2VHL substrate HIF-1α. TRIP12 associates with BRD4 via CRL2VHL and specifically assembles K29-linked ubiquitin chains, facilitating the formation of K29/K48-branched ubiquitin chains and accelerating the assembly of K48 linkage by CRL2VHL. Consequently, TRIP12 promotes the PROTAC-induced apoptotic response. TRIP12 also supports the efficiency of other degraders that target CRABP2 or TRIM24 or recruit CRBN. These observations define TRIP12 and K29/K48-branched ubiquitin chains as accelerators of PROTAC-directed targeted protein degradation, revealing a cooperative mechanism of branched ubiquitin chain assembly unique to the degradation of neo-substrates.

Comparative efficacy and safety of tyrosine kinase inhibitors for thyroid cancer: a systematic review and meta-analysis.

The tyrosine kinase inhibitors (TKIs) sorafenib, lenvatinib, vandetanib, and cabozantinib are currently used for thyroid cancer treatment; however, the differences in their clinical efficacy and toxicity remain unclear. This meta-analysis assessed the efficacy and toxicity of these four TKIs based on 34 studies. The pooled incidence of partial response (PR), stable disease (SD), TKI-related adverse events (AEs), and pooled median progression-free survival (PFS) were calculated with 95% confidence intervals (CI). Complete response to TKIs was extremely rare (0.3%). The highest PR rate and longest PFS were observed for lenvatinib in differentiated thyroid cancer (69%, 95% CI: 57-81 and 19 months, 95% CI: 9-29, respectively) and vandetanib in medullary thyroid cancer (40%, 95% CI: 25-56 and 31 months, 95% CI: 19-43, respectively). Although the discontinuation rate due to AEs was similar for each TKI, there was a difference in the most frequently observed AE for each TKI (hand-foot syndrome for sorafenib, hypertension and proteinuria for lenvatinib, and QTc prolongation for vandetanib). The identified differences in the TKI efficacy and AE profiles may provide a better understanding of thyroid cancer treatment. Although TKIs are promising agents for thyroid cancer treatment, they are unlikely to lead to a cure. Thus, even in the TKI era, a multimodal treatment including surgery, radioiodine therapy, external beam radiotherapy, and TKIs is required to optimize patient chances of improved survival.