The KDM5A/RBP2 histone demethylase represses NOTCH signaling to sustain neuroendocrine differentiation and promote small cell lung cancer tumorigenesis.

More than 90% of small cell lung cancers (SCLCs) harbor loss-of-function mutations in the tumor suppressor gene RB1 The canonical function of the RB1 gene product, pRB, is to repress the E2F transcription factor family, but pRB also functions to regulate cellular differentiation in part through its binding to the histone demethylase KDM5A (also known as RBP2 or JARID1A). We show that KDM5A promotes SCLC proliferation and SCLC's neuroendocrine differentiation phenotype in part by sustaining expression of the neuroendocrine transcription factor ASCL1. Mechanistically, we found that KDM5A sustains ASCL1 levels and neuroendocrine differentiation by repressing NOTCH2 and NOTCH target genes. To test the role of KDM5A in SCLC tumorigenesis in vivo, we developed a CRISPR/Cas9-based mouse model of SCLC by delivering an adenovirus (or an adeno-associated virus [AAV]) that expresses Cre recombinase and sgRNAs targeting Rb1, Tp53, and Rbl2 into the lungs of Lox-Stop-Lox Cas9 mice. Coinclusion of a KDM5A sgRNA decreased SCLC tumorigenesis and metastasis, and the SCLCs that formed despite the absence of KDM5A had higher NOTCH activity compared to KDM5A+/+ SCLCs. This work establishes a role for KDM5A in SCLC tumorigenesis and suggests that KDM5 inhibitors should be explored as treatments for SCLC.

Resected WHO grade I meningioma and predictors of local control.

INTRODUCTION: Despite optimal surgical resection, meningiomas may recur, with increasing grade and the degree of resection being predictive of risk. We hypothesize that an increasing Ki67 correlates with a higher risk of recurrence of resected WHO grade I meningiomas. METHODS: The study population consisted of patients with resected WHO grade 1 meningiomas in locations outside of the base of skull. Digitally scanned slides stained for Ki67 were analyzed using automatic image analysis software in a standardized fashion. RESULTS: Recurrence was observed in 53 (17.7%) of cases with a median follow up time of 25.8 months. Ki67 ranged from 0 to 30%. Median Ki67 was 5.1% for patients with recurrence and 3.5% for patients without recurrence. In unadjusted analyses, high Ki-67 (≥ 5 vs. < 5) vs. ≥ 5) was associated with over a twofold increased risk of recurrence (13.1% vs. 27% respectively; HR 2.1731; 95% CI [1.2534, 3.764]; p = 0.006). After Adjusting for patient or tumor characteristics, elevated Ki-67 remained significantly correlated with recurrence. Grade 4 Simpson resection was noted in 71 (23.7%) of patients and it was associated with a significantly increased risk of recurrence (HR 2.56; 95% CI [1.41, 4.6364]; p = 0.002). CONCLUSIONS: WHO grade 1 meningiomas exhibit a significant rate of recurrence following resection. While Ki-67 is not part of the WHO grading criteria of meningiomas, a value greater than 5% is an independent predictor for increased risk of local recurrence following surgical resection.

Stereotactic radiosurgery for management of vestibular schwannoma: a short review.

Management options for newly diagnosed vestibular schwannoma (VS) include observation, surgery, or radiation. There are no randomized trials to guide management of patients with VS. This article is a short review of the role of stereotactic radiosurgery in management of newly diagnosed VS.

SCCRO3 (DCUN1D3) antagonizes the neddylation and oncogenic activity of SCCRO (DCUN1D1).

The activity of cullin-RING type ubiquitination E3 ligases is regulated by neddylation, a process analogous to ubiquitination that culminates in covalent attachment of the ubiquitin-like protein Nedd8 to cullins. As a component of the E3 for neddylation, SCCRO/DCUN1D1 plays a key regulatory role in neddylation and, consequently, cullin-RING ligase activity. The essential contribution of SCCRO to neddylation is to promote nuclear translocation of the cullin-ROC1 complex. The presence of a myristoyl sequence in SCCRO3, one of four SCCRO paralogues present in humans that localizes to the membrane, raises questions about its function in neddylation. We found that although SCCRO3 binds to CAND1, cullins, and ROC1, it does not efficiently bind to Ubc12, promote cullin neddylation, or conform to the reaction processivity paradigms, suggesting that SCCRO3 does not have E3 activity. Expression of SCCRO3 inhibits SCCRO-promoted neddylation by sequestering cullins to the membrane, thereby blocking its nuclear translocation. Moreover, SCCRO3 inhibits SCCRO transforming activity. The inhibitory effects of SCCRO3 on SCCRO-promoted neddylation and transformation require both an intact myristoyl sequence and PONY domain, confirming that membrane localization and binding to cullins are required for in vivo functions. Taken together, our findings suggest that SCCRO3 functions as a tumor suppressor by antagonizing the neddylation activity of SCCRO.

Targeted Intraoperative Radiotherapy (TARGIT-IORT) for Early-Stage Invasive Breast Cancer: A Single Institution Experience.

Purpose/Objective: We present our single-institution experience in the management of invasive breast cancer with targeted intraoperative radiotherapy (TARGIT-IORT), focusing on patient suitability for IORT determined by the American Society for Radiation Oncology (ASTRO) Accelerated Partial Breast Irradiation (APBI) consensus guidelines. Materials/Methods: We identified 237 patients treated for biopsy-proven early-stage invasive breast cancer using low energy x-ray TARGIT-IORT at the time of lumpectomy between September 2013 and April 2020 who were prospectively enrolled in an institutional review board (IRB) approved database. We retrospectively reviewed preoperative and postoperative clinicopathologic factors to determine each patient's ASTRO APBI suitability (suitable, cautionary or unsuitable) according to the 2017 consensus guidelines (CG). Change in suitability group was determined based on final pathology. Kaplan-Meier methods were used to estimate the survival probability and recurrence probability across time. Results: 237 patients were included in this analysis, based on preoperative clinicopathologic characteristics, 191 (80.6%) patients were suitable, 46 (19.4%) were cautionary and none were deemed unsuitable. Suitability classification changed in 95 (40%) patients based on final pathology from lumpectomy. Increasing preoperative lesion size or a body mass index (BMI) ≥ 30 kg/m2 were significant predictors for suitability group change. Forty-one (17.3%) patients received additional adjuvant whole breast radiotherapy after TARGIT-IORT. At a median follow up of 38.2 months (range 0.4 - 74.5), five (2.1%) patients had ipsilateral breast tumor recurrences (IBTR), including two (0.8%) true local recurrences defined as a recurrence in the same quadrant as the initial lumpectomy bed with the same histology as the initial tumor. IBTR occurred in 1/103 (0.09%) patient in the post-op suitable group, 4/98 (4.08%) patients in the post-op cautionary group, and no patients in the post-op unsuitable group. At 3-years, the overall survival rate was 98.4% and the local recurrence free survival rate was 97.1%. Conclusion: There is a low rate of IBTR after TARGIT-IORT when used in appropriately selected patients. Change in suitability classification pre to postoperatively is common, highlighting a need for further investigation to optimize preoperative patient risk stratification in this setting. Patients who become cautionary or unsuitable based on final pathology should be considered for additional adjuvant therapy.

Radiotherapy for locally advanced pancreatic ductal adenocarcinoma.

Locally advanced, unresectable pancreatic ductal adenocarcinoma has a poor prognosis with a median overall survival of 10-16 months. It is defined by tumor involvement of neighboring blood vessels that precludes resection. Standard doses of conventionally fractionated radiation have had little effect on overall survival in this setting, although they are associated with improved progression-free survival and time off chemotherapy. Evolving radiotherapy techniques have allowed for higher, ablative doses of radiotherapy to target tumor while also respecting normal tissue constraints of neighboring radiosensitive structures in the gastrointestinal tract. Moreover, advancements in image guidance, organ motion management, and the use of adaptive planning have enabled safe delivery of higher, ablative doses of radiation. This has resulted in improved survival. This review will summarize the expanding role of radiotherapy in the management of locally advanced, unresectable pancreatic cancer.

Cells Lacking the RB1 Tumor Suppressor Gene Are Hyperdependent on Aurora B Kinase for Survival.

Small cell lung cancer (SCLC) accounts for 15% of lung cancers and is almost always linked to inactivating RB1 and TP53 mutations. SCLC frequently responds, albeit briefly, to chemotherapy. The canonical function of the RB1 gene product RB1 is to repress the E2F transcription factor family. RB1 also plays both E2F-dependent and E2F-independent mitotic roles. We performed a synthetic lethal CRISPR/Cas9 screen in an RB1 -/- SCLC cell line that conditionally expresses RB1 to identify dependencies that are caused by RB1 loss and discovered that RB1 -/- SCLC cell lines are hyperdependent on multiple proteins linked to chromosomal segregation, including Aurora B kinase. Moreover, we show that an Aurora B kinase inhibitor is efficacious in multiple preclinical SCLC models at concentrations that are well tolerated in mice. These results suggest that RB1 loss is a predictive biomarker for sensitivity to Aurora B kinase inhibitors in SCLC and perhaps other RB1 -/- cancers. SIGNIFICANCE: SCLC is rarely associated with actionable protooncogene mutations. We did a CRISPR/Cas9-based screen that showed that RB1 -/- SCLC are hyperdependent on AURKB, likely because both genes control mitotic fidelity, and confirmed that Aurora B kinase inhibitors are efficacious against RB1 -/- SCLC tumors in mice at nontoxic doses.See related commentary by Dick and Li, p. 169.This article is highlighted in the In This Issue feature, p. 151.

Oncogenic function of SCCRO5/DCUN1D5 requires its Neddylation E3 activity and nuclear localization.

PURPOSE: To determine mechanisms by which SCCRO5 (aka DCUN1D5) promotes oncogenesis. EXPERIMENTAL DESIGN: SCCRO5 mRNA and protein expression were assessed in 203 randomly selected primary cancer tissue samples, matched histologically normal tissues, and cell lines by use of real-time PCR and Western blot analysis. SCCRO5 overexpression was correlated with survival. The effect of SCCRO5 knockdown on viability was assessed in selected cancer cell lines. Structure-function studies were performed to determine the SCCRO5 residues required for binding to the neddylation components, for neddylation-promoting activity, and for transformation. RESULTS: In oral and lung squamous cell carcinomas, SCCRO5 mRNA levels corresponded with protein levels and overexpression correlated with decreased disease-specific survival. Knockdown of SCCRO5 by RNAi resulted in a selective decrease in the viability of cancer cells with high endogenous levels, suggesting the presence of oncogene addiction. SCCRO5 promoted cullin neddylation while maintaining conserved reaction processivity paradigms involved in ubiquitin and ubiquitin-like protein conjugation, establishing it as a component of the neddylation E3. Neddylation activities in vitro required the potentiating of neddylation (PONY) domain but not the nuclear localization sequence (NLS) domain. In contrast, both the NLS domain and the PONY domain were required for transformation of NIH-3T3 cells. CONCLUSIONS: Our data suggest that SCCRO5 has oncogenic potential that requires its function as a component of the neddylation E3. Neddylation activity and nuclear localization of SCCRO5 are important for its in vivo function.