RAD6 inhibition enhances paclitaxel sensitivity of triple negative breast cancer cells by aggravating mitotic spindle damage.

BACKGROUND: Paclitaxel (PTX), a first-line therapy for triple negative breast cancers (TNBC) induces anti-tumor activity by microtubule stabilization and inhibition of cell division. Its dose-limiting toxicity and short half-life, however, pose clinical challenges underscoring the need for strategies that increase its efficiency. RAD6, a E2 ubiquitin conjugating enzyme, is associated with centrosomes at all phases of cell cycle. Constitutive overexpression of the RAD6B homolog in normal breast cells induces centrosome amplification and multipolar spindle formation, indicating its importance in centrosome regulation. METHODS: TNBC centrosome numbers were scored by pericentrin immunostaining. PTX sensitivities and interactions with SMI#9, a RAD6-selective small molecule inhibitor, on TNBC cell survival were analyzed by MTT and colony forming assays and an isogenic MDA-MB-468 TNBC model of PTX resistance. The molecular mechanisms underlying PTX and SMI#9 induced cytotoxicity were determined by flow cytometry, immunoblot analysis of cyclin B1 and microtubule associated protein TAU, and dual immunofluorescence staining of TAU and α-tubulin. RESULTS: Our data show aberrant centrosome numbers and that PTX sensitivities are not correlated with TNBC BRCA1 status. Combining PTX with SMI#9 synergistically enhances PTX sensitivities of BRCA1 wild-type and mutant TNBC cells. Whereas SMI#9/PTX combination treatment increased cyclin B1 levels in MDA-MB-468 cells, it induced cyclin B1 loss in HCC1937 cells with accumulation of reproductively dead giant cells, a characteristic of mitotic catastrophe. Cell cycle analysis revealed drug-induced accumulation of tetraploid cells in S and G2/M phases, and robust increases in cells with 4 N DNA content in HCC1937 cells. TAU overexpression is associated with reduced PTX efficacy. Among the six TAU isoforms, both SMI#9 and PTX downregulated 1N3R TAU in MDA-MB-468 and HCC1937 cells, suggesting a common mechanism of 1N3R regulation. Dual TAU and α-tubulin immunostaining showed that SMI#9 induces monopolar mitotic spindles. Using the isogenic model of PTX resistance, we show that SMI#9 treatment restores PTX sensitivity. CONCLUSIONS: These data support a common mechanism of microtubule regulation by SMI#9 and PTX and suggest that combining PTX with RAD6 inhibitor may be beneficial for increasing TNBC sensitivities to PTX and alleviating toxicity. This study demonstrates a new role for RAD6 in regulating microtubule dynamics.

The Escherichia coli CydX protein is a member of the CydAB cytochrome bd oxidase complex and is required for cytochrome bd oxidase activity.

Cytochrome bd oxidase operons from more than 50 species of bacteria contain a short gene encoding a small protein that ranges from ∼30 to 50 amino acids and is predicted to localize to the cell membrane. Although cytochrome bd oxidases have been studied for more than 70 years, little is known about the role of this small protein, denoted CydX, in oxidase activity. Here we report that Escherichia coli mutants lacking CydX exhibit phenotypes associated with reduced oxidase activity. In addition, cell membrane extracts from ΔcydX mutant strains have reduced oxidase activity in vitro. Consistent with data showing that CydX is required for cytochrome bd oxidase activity, copurification experiments indicate that CydX interacts with the CydAB cytochrome bd oxidase complex. Together, these data support the hypothesis that CydX is a subunit of the CydAB cytochrome bd oxidase complex that is required for complex activity. The results of mutation analysis of CydX suggest that few individual amino acids in the small protein are essential for function, at least in the context of protein overexpression. In addition, the results of analysis of the paralogous small transmembrane protein AppX show that the two proteins could have some overlapping functionality in the cell and that both have the potential to interact with the CydAB complex.

Areas of strength and opportunities for growth in translational science education and training: Results of a scoping review from the NCATS Education Branch.

Translational science education and training (E&T) aims to prepare the translational workforce to accelerate progress along the translational pipeline toward solutions that improve human health. In 2020-2021, the National Center for Advancing Translational Sciences (NCATS) Education Branch conducted a scoping review of the E&T literature with this focus. The review used the methodological framework proposed by Arksey and O'Malley. PubMed, Education Resources Information Center (ERIC), and Embase were searched, and forward citations conducted. Screening of titles, abstracts, and full text identified 44 included articles. Data extraction facilitated analysis of E&T content, audiences, modalities, evaluations, and recommendations. The NCATS Translational Science Principles were used to identity described or recommended E&T content. Twenty-nine articles described a translational science E&T opportunity or its evaluation, and another 15 articles offered recommendations for translational science E&T. The most prevalent NCATS Translational Science Principles were boundary-crossing partnerships (77%) and cross-disciplinary team science (75%). Among publications describing E&T opportunities, the most reported modalities were experiential learning (64%) and courses (61%) and the most reported participants were graduate students (68%) and postdoctoral fellows (54%). About half of these articles (n = 15) reported an evaluation, covering a range of proximal to distal outcomes. Recommendations emphasized the value of translational science E&T across training and career stages and the use of varied modalities to reach diverse audiences. This review highlights strengths and opportunities for growth in translational science E&T. Enhancements to content, expansion of participants and modalities, and rigorous evaluations will contribute to building a highly qualified, diverse translational science workforce.

COPD and lung cancer incidence in the Women's Health Initiative Observational Study: A brief report.

OBJECTIVES: Lung cancer is the leading cause of cancer mortality in both men and women in the United States. COPD is associated with lung cancer independently of cigarette smoking, but remains understudied in women. Utilizing data from the Women's Health Initiative Observational Study (WHI-OS), this report investigates the association between COPD and development of lung cancer, with a focus on ethnicity and cancer subtype. MATERIALS AND METHODS: The WHI-OS, part of the larger Women's Health Initiative (WHI), is comprised of postmenopausal women between ages 50 and 79 years old at enrollment. Self-administered questionnaires were utilized to gather baseline demographic, socioeconomic, and behavioral information from participants. For this analysis, COPD status was determined at study entry (baseline) and on annual survey (incident). Information on the primary outcome of interest, diagnosis of lung cancer, was also collected annually. RESULTS AND CONCLUSION: Of the 92,789 women examined, 1,536 developed lung cancer. Overall, women with COPD were 1.64 times more likely to develop lung cancer than those without COPD, after adjusting for smoking status and intensity, ethnicity, education, body mass index, and income (HR = 1.64, 95 % CI: 1.43, 1.89). The relationship between COPD and lung cancer was not found to be significantly different between ethnic groups (p-value = 0.697). The associations between COPD and lung cancer was similar across subtypes (HR range 1.31-2.16), after adjusting for smoking status and intensity. COPD increases risk of lung cancer in women, thus they may benefit from more intensive surveillance compared to similar women without COPD.