Determination of adversity and the no observed adverse effect level (NOAEL) in nonclinical toxicity studies are important components in the overall assessment of the potential for human risk during pharmaceutical development. Resources exist to guide adversity decisions in general, for findings in ganglia of the peripheral nervous system (PNS), and for gliosis in the central nervous system (CNS). The objective of this opinion article is to describe considerations that may apply when determining the adversity (or lack thereof) of nerve fiber degeneration (NFD) in either the CNS or PNS following intrathecal (IT) administration of oligonucleotide (ON) therapeutics (such as antisense oligonucleotides and short interfering RNAs). It is important to differentiate IT delivery procedure-related NFD effects from ON-related effects or ON-related exacerbation of procedure-related findings. This article presents evidence-based approaches for deciding whether NFD associated with IT ON administration is an adverse microscopic finding in the brain, spinal cord, spinal nerve roots, ganglia, and/or nerves. In the authors' collective experience, nonextensive (i.e., regionally restricted), minimal or mild NFD unaccompanied by functional or behavioral deficits, neuronal necrosis, or a substantial inflammatory response in neural tissue can be interpreted as nonadverse.

Direct delivery of therapeutics to the central nervous system (CNS) greatly expands opportunities to treat neurological diseases but is technically challenging. This opinion outlines principal technical aspects of direct CNS delivery via intracerebroventricular (ICV) or intrathecal (IT) injection to common nonclinical test species (rodents, dogs, and nonhuman primates) and describes procedure-related clinical and histopathological effects that confound interpretation of test article-related effects. Direct dosing is by ICV injection in mice due to their small body size, while other species are dosed IT in the lumbar cistern. The most frequent procedure-related functional effects are transient absence of lower spinal reflexes after IT injection or death soon after ICV dosing. Common procedure-related microscopic findings in all species include leukocyte infiltrates in CNS meninges or perivascular (Virchow-Robin) spaces; nerve fiber degeneration in the spinal cord white matter (especially dorsal and lateral tracts compressed by dosing needles or indwelling catheters), spinal nerve roots, and sciatic nerve; meningeal fibrosis at or near IT injection sites; hemorrhage; and gliosis. Findings typically are minimal to occasionally mild. Findings tend to be more severe and/or have a higher incidence in the spinal cord segments and spinal nerve roots at or close to the site of administration.

PDF file - 120K, This is a more detailed discussion of the microarray data.

GO pathway analyses per gene cluster in Figure 6A - LNCaP and C4-2.

PDF file - 213K, Supplemental Table 1 is a table that lists the average sum of the adjusted lesion scores (SALS) for each lobe of the prostate, as well as the average score for the most severe and most common lesion in each lobe. Supplemental tables 2 through 5 provide detailed analysis of the microarray data.

Gene clusters corresponding with Figure 6A - LNCaP cells.

Dose response curves of CBTX and DCTX in LAPC4, VCaP and LNCaP-abl cells. C4-2 xenograft tumor growth response to CBTX in mice. Cleaved PARP western blot analysis of LNCaP and C4-2 cells treated with 1nM CBTX or DCTX.

Bivariate flow cytometry analyses of LNCaP and C4-2 cells treated with 1nM DCTX for 16 or 48h.

SF1: Analysis of USP22 expression with known drivers of disease progression; SF2: USP22 modulates DNA repair factors expression and survival after DNA damage; SF3: Genetically engineered mouse model of tumor-associated USP22 expression; SF4: The USP22-sensitive ubiquitylome reveals altered modification of DNA repair proteins; SF5: USP22 deubiquitylates the NER protein XPC, modulating foci formation.

Supplemental Methods from Novel Actions of Next-Generation Taxanes Benefit Advanced Stages of Prostate Cancer

Supplemental Methods and Figure Legends

Supplementary Figures S1-6 Supplemental Fig. S1. ErbB3 and ErbB4 expression in melanoma cell lines. Supplemental Fig. S2. Depletion of NRG1 inhibits ErbB3 downstream signaling and cell growth in WT/WT melanoma cell lines. Supplemental Fig. S3. Depletion of ErbB3 reduces AKT and ERK1/2 phosphorylation. Supplemental Fig. S4. huHER3-8 reduces AKT phosphorylation. Supplemental Fig. S5. Pertuzumab reduces phosphorylation of AKT and ERK1/2 and inhibits cell growth. Supplemental Fig. S6. MEK inhibitors increase pertuzumab efficacy in xenografts.

Abstract Emerging evidence indicates the deubiquitinase USP22 regulates transcriptional activation and modification of target substrates to promote pro-oncogenic phenotypes. Here, in vivo characterization of tumor-associated USP22 upregulation and unbiased interrogation of USP22-regulated functions in vitro demonstrated critical roles for USP22 in prostate cancer. Specifically, clinical datasets validated that USP22 expression is elevated in prostate cancer, and a novel murine model demonstrated a hyperproliferative phenotype with prostate-specific USP22 overexpression. Accordingly, upon overexpression or depletion of USP22, enrichment of cell-cycle and DNA repair pathways was observed in the USP22-sensitive transcriptome and ubiquitylome using prostate cancer models of clinical relevance. Depletion of USP22 sensitized cells to genotoxic insult, and the role of USP22 in response to genotoxic insult was further confirmed using mouse adult fibroblasts from the novel murine model of USP22 expression. As it was hypothesized that USP22 deubiquitylates target substrates to promote protumorigenic phenotypes, analysis of the USP22-sensitive ubiquitylome identified the nucleotide excision repair protein, XPC, as a critical mediator of the USP22-mediated response to genotoxic insult. Thus, XPC undergoes deubiquitylation as a result of USP22 function and promotes USP22-mediated survival to DNA damage. Combined, these findings reveal unexpected functions of USP22 as a driver of protumorigenic phenotypes and have significant implications for the role of USP22 in therapeutic outcomes. Significance: The studies herein present a novel mouse model of tumor-associated USP22 overexpression and implicate USP22 in modulation of cellular survival and DNA repair, in part through regulation of XPC.

C-terminal Src kinase (Csk) is one of the critical negative regulators of the Src family of kinases. The Src family of kinases are nonreceptor tyrosine kinases that regulate inflammation, cell proliferation, motility, and adhesion. To investigate potential histologic lesions associated with systemic loss of Csk gene activity in adult mice, conditional Csk-knockout mice were examined. Cre-mediated systemic excision of Csk induced by tamoxifen treatment resulted in multiorgan inflammation. Specifically, induction of Csk gene excision with three days of tamoxifen treatment resulted in greater than 90% gene excision. Strikingly, these mice developed enteritis that ranged from minimal and suppurative to severe, fibrinonecrosuppurative and hemorrhagic. Other inflammatory lesions included suppurative pneumonia, gastritis, and myocarditis, and increased numbers of inflammatory cells within the hepatic parenchyma. When tamoxifen treatment was reduced from three days to one day in an effort to lower the level of Csk gene excision and limit lesion development, the mice developed severe suppurative to pyogranulomatous pneumonia and minimal to mild suppurative enteritis. Lesions observed secondary to Csk gene excision suggest important roles for Csk in downregulating the proinflammatory activity of the Src family of kinases and limiting neutrophil-mediated inflammation.

Clinical evidence suggests that cyclin D1b, a variant of cyclin D1, is associated with tumor progression and poor outcome. However, the underlying molecular basis was unknown. Here, novel models were created to generate a genetic switch from cyclin D1 to cyclin D1b. Extensive analyses uncovered overlapping but non-redundant functions of cyclin D1b compared to cyclin D1 on developmental phenotypes, and illustrated the importance of the transcriptional regulatory functions of cyclin D1b in vivo. Data obtained identify cyclin D1b as an oncogene, wherein cyclin D1b expression under the endogenous promoter induced cellular transformation and further cooperated with known oncogenes to promote tumor growth in vivo. Further molecular interrogation uncovered unexpected links between cyclin D1b and the DNA damage/PARP1 regulatory networks, which could be exploited to suppress cyclin D1b-driven tumors. Collectively, these data are the first to define the consequence of cyclin D1b expression on normal cellular function, present evidence for cyclin D1b as an oncogene, and provide pre-clinical evidence of effective methods to thwart growth of cells dependent upon this oncogenic variant.

Spinal and bulbar muscular atrophy (SBMA) is a neurodegenerative disease caused by a polyglutamine expansion in the androgen receptor (AR) and is associated with misfolding and aggregation of the mutant AR. We investigated the role of an interdomain interaction between the amino (N)-terminal FxxLF motif and carboxyl (C)-terminal AF-2 domain in a mouse model of SBMA. Male transgenic mice expressing polyQ-expanded AR with a mutation in the FxxLF motif (F23A) to prevent the N/C interaction displayed substantially improved motor function compared with N/C-intact AR-expressing mice and showed reduced pathological features of SBMA. Serine 16 phosphorylation was substantially enhanced by the F23A mutation; moreover, the protective effect of AR F23A was dependent on this phosphorylation. These results reveal an important role for the N/C interaction on disease onset in mice and suggest that targeting AR conformation could be a therapeutic strategy for patients with SBMA.

Abstract The treatment options remain limited for patients with melanoma who are wild-type for both BRAF and NRAS (WT/WT). We demonstrate that a subgroup of WT/WT melanomas display high basal phosphorylation of ErbB3 that is associated with autocrine production of the ErbB3 ligand neuregulin-1 (NRG1). In WT/WT melanoma cells displaying high levels of phospho-ErbB3, knockdown of NRG1 reduced cell viability and was associated with decreased phosphorylation of ErbB3, its coreceptor ErbB2, and its downstream target, AKT. Similar effects were observed by targeting ErbB3 with either siRNAs or the neutralizing ErbB3 monoclonal antibodies huHER3-8 and NG33. In addition, pertuzumab-mediated inhibition of ErbB2 heterodimerization decreased AKT phosphorylation, cell growth in vitro, and xenograft growth in vivo. Pertuzumab also potentiated the effects of MEK inhibitor on WT/WT melanoma growth in vitro and in vivo. These findings demonstrate that targeting ErbB3–ErbB2 signaling in a cohort of WT/WT melanomas leads to tumor growth reduction. Together, these studies support the rationale to target the NRG1–ErbB3–ErbB2 axis as a novel treatment strategy in a subset of cutaneous melanomas. Cancer Res; 75(17); 3554–67. ©2015 AACR.

Purpose: To improve the outcomes of patients with castration-resistant prostate cancer (CRPC), there is an urgent need for more effective therapies and approaches that individualize specific treatments for patients with CRPC. These studies compared the novel taxane cabazitaxel with the previous generation docetaxel, and aimed to determine which tumors are most likely to respond. Experimental design: Cabazitaxel and docetaxel were compared via in vitro modeling to determine the molecular mechanism, biochemical and cell biologic impact, and cell proliferation, which was further assessed ex vivo in human tumor explants. Isogenic pairs of RB knockdown and control cells were interrogated in vitro and in xenograft tumors for cabazitaxel response. Results: The data herein show that (i) cabazitaxel exerts stronger cytostatic and cytotoxic response compared with docetaxel, especially in CRPC; (ii) cabazitaxel induces aberrant mitosis, leading to pyknotic and multinucleated cells; (iii) taxanes do not act through the androgen receptor (AR); (iv) gene-expression profiling reveals distinct molecular actions for cabazitaxel; and (v) tumors that have progressed to castration resistance via loss of RB show enhanced sensitivity to cabazitaxel. Conclusions: Cabazitaxel not only induces improved cytostatic and cytotoxic effects, but also affects distinct molecular pathways, compared with docetaxel, which could underlie its efficacy after docetaxel treatment has failed in patientswithCRPC. Finally, RB is identified as the first potential biomarker that could define the therapeutic response to taxanes in metastatic CRPC. This would suggest that loss of RB function induces sensitization to taxanes, which could benefit up to 50% of CRPC cases. Clin Cancer Res; 21(4); 795–807. 2015 AACR.