Opi1-mediated transcriptional modulation orchestrates genotoxic stress response in budding yeast

In budding yeast, the transcriptional repressor Opi1 regulates phospholipid biosynthesis by repressing expression of genes containing inositol-sensitive upstream activation sequences. Upon genotoxic stress, cells activate the DNA damage response to coordinate a complex network of signaling pathways aimed at preserving genomic integrity. Here, we reveal that Opi1 is important to modulate transcription in response to genotoxic stress. We find that cells lacking Opi1 exhibit hypersensitivity to genotoxins, along with a delayed G1-to-S-phase transition and decreased gamma-H2A levels. Transcriptome analysis using RNA sequencing reveals that Opi1 plays a central role in modulating essential biological processes during methyl methanesulfonate (MMS)-associated stress, including repression of phospholipid biosynthesis and transduction of mating signaling. Moreover, Opi1 induces sulfate assimilation and amino acid metabolic processes, such as arginine and histidine biosynthesis and glycine catabolism. Furthermore, we observe increased mitochondrial DNA instability in opi1Δ cells upon MMS treatment. Notably, we show that constitutive activation of the transcription factor Ino2-Ino4 is responsible for genotoxin sensitivity in Opi1-deficient cells, and the production of inositol pyrophosphates by Kcs1 counteracts Opi1 function specifically during MMS-induced stress. Overall, our findings highlight Opi1 as a critical sensor of genotoxic stress in budding yeast, orchestrating gene expression to facilitate appropriate stress responses.

P11.72.A Glioblastoma in elderly patients. Which is the best treatment option?

Background

Glioblastoma (GBM) is the most common and aggressive primary malignant brain tumor in adults, and it is associated with a poor prognosis in the elderly. The current standard of care for newly diagnosed GBM is maximal surgical resection, followed by radiotherapy plus concomitant and adjuvant temozolomide (TMZ). In elderly patients with GBM, short-courses of radiotherapy with TMZ are used.

Material and Methods

We performed a single-center retrospective analysis of elderly GBM patients treated from 2013 to 2020. The primary endpoint was to evaluate progression free survival (PFS) and overall survival (OS) according to treatment received (TMZ and standard radiotherapy (60 Gy over a period of 6 weeks) vs TMZ and short-course radiotherapy (40 Gy in 15 fractions)). Secondary endpoints were analysis of population demographics and major toxicities associated to treatment.

Results

Twenty-two patients were identified. The median age was 72 years (range 65- 80), 18 (85.7%) patients were in ECOG-PS 0-1, 12 (57.1%) were males and all patients had undergone partial or complete resection surgery. Eleven (52.4%) patients received TMZ and standard radiotherapy and 10 (47.6%) patients received TMZ and short-course radiotherapy. Three (14.3%) patients had complete remission, 11 (52.4%) patients had partial response, 2 (9.5%) patients presented stable disease and 5 (23.8%) patients had disease progression. Median OS was 9 months (95% CI, 3.6 to 14.4) with TMZ with standard radiotherapy and 8 months (95% CI, 1.8 to 14.2) with TMZ and short-course radiotherapy (p=0.322). Median PFS was 5 months (95% CI, 2.8 to 7.2) with TMZ with standard radiotherapy and 6 months (95% CI, 3.1 to 8.9) with TMZ and short-course radiotherapy (p=0.944). Most common toxicities were hematological, with 5 (23.8%) patients presented thrombocytopenia grade 2 or higher. Five (23.8%) patients presented grade 3/4 toxicities (2 (9.5%) patients presented thrombocytopenia grade 4, 1 (4.8%) patient presented thrombocytopenia grade 3, and 2 (9.5%) patients presented anemia grade 3.

Conclusion

The prognosis of GBM remains poor besides standard therapy. TMZ and short-course radiotherapy should be an option in elderly patients due to its non-inferiority. Elderly patients should undergo a careful geriatric evaluation before starting treatment.

Critical steps in fluoroquinolones and carbapenems prescriptions: results from a prospective clinical audit

Antibiotic misuse is associated with emergence of resistance and high expenditures. Fluoroquinolones (FQ) and carbapenems (CP) are drugs with considerable potential of resistance development and its disseminated use is a concern. We undertook a prospective clinical audit to evaluate prescriptions of FQ and CP in a multistep process. Each prescription was unfolded in the following steps: indication for antimicrobial therapy; adequacy of initial prescription, dosage and route; previous cultures; and parenteral-oral transition. There was no antibiotics indication in 8.9% of FQ and 1.5% of CP group (p = 0.07). In CP 25.8% of initial schemes were inappropriate (21% in FQ). Lack of switch to oral therapy comprised 25% of monthly costs of FQ. Inadequacy in initial choice accounted for 13.6% of CP expenses. We concluded that, in spite of infection control restrictive policies, inappropriateness of antibiotic usage is worrisome. Clinical audit in a multistep approach may identify possible flaws in this process.