This systematic review and meta-analysis is the first to evaluate the evidence for an association between metformin use and cancer outcomes in patients undergoing treatment with curative intent for individual cancer types. Our findings suggest that adjuvant metformin could have beneficial effects, particularly on cancer outcomes in colorectal and prostate cancer. Randomised trials are warranted.
BackgroundThere is a considerable body of pre-clinical, epidemiological and randomised data to support the hypothesis that aspirin has the potential to be an effective adjuvant cancer therapy.MethodsAdd-Aspirin is a phase III, multi-centre, double-blind, placebo-controlled randomised trial with four parallel cohorts. Patients who have undergone potentially curative treatment for breast (n = 3100), colorectal (n = 2600), gastro-oesophageal (n = 2100) or prostate cancer (n = 2120) are registered into four tumour specific cohorts. All cohorts recruit in the United Kingdom, with the breast and gastro-oesophageal cohort also recruiting in India. Eligible participants first undertake an active run-in period where 100 mg aspirin is taken daily for approximately eight weeks. Participants who are able to adhere and tolerate aspirin then undergo a double-blind randomisation and are allocated in a 1:1:1 ratio to either 100 mg aspirin, 300 mg aspirin or a matched placebo to be taken daily for at least five years. Those participants ≥ 75 years old are only randomised to 100 mg aspirin or placebo due to increased toxicity risk.ResultsThe primary outcome measures are invasive disease-free survival for the breast cohort, disease-free survival for the colorectal cohort, overall survival for the gastro-oesophageal cohort, and biochemical recurrence-free survival for the prostate cohort, with a co-primary outcome of overall survival across all cohorts. Secondary outcomes include adherence, toxicity including serious haemorrhage, cardiovascular events and some cohort specific measures.ConclusionsThe Add-Aspirin trial investigates whether regular aspirin use after standard therapy prevents recurrence and prolongs survival in participants with four non-metastatic common solid tumours.
This stage-stratified approach to the management of KS achieves high survival in patients with advanced KS and reduces exposure to chemotherapy in patients with early-stage KS.
Background
Enhanced GABA activity in the brain and a hyperactive hypothalamic-pituitary-gonadal axis are associated with polycystic ovary syndrome (PCOS), the most common form of anovulatory infertility. Women with PCOS exhibit elevated cerebrospinal fluid GABA levels and preclinical models of PCOS exhibit increased GABAergic input to GnRH neurons, the central regulators of reproduction. The arcuate nucleus (ARN) is postulated as the anatomical origin of elevated GABAergic innervation; however, the functional role of this circuit is undefined.
Methods
We employed a combination of targeted optogenetic and chemogenetic approaches to assess the impact of acute and chronic ARN GABA neuron activation. Selective acute activation of ARN GABA neurons and their fiber projections was coupled with serial blood sampling for luteinizing hormone secretion in anesthetized male, female and prenatally androgenised (PNA) mice modelling PCOS. In addition, GnRH neuron responses to ARN GABA fiber stimulation were recorded in
ex vivo
brain slices. Chronic activation of ARN GABA neurons in healthy female mice was coupled with reproductive phenotyping for PCOS-like features.
Findings
Acute stimulation of ARN GABA fibers adjacent to GnRH neurons resulted in a significant and long-lasting increase in LH secretion in male and female mice. The amplitude of this response was blunted in PNA mice, which also exhibited a blunted LH response to GnRH administration. Infrequent and variable GABA
A
-dependent changes in GnRH neuron firing were observed in brain slices. Chronic activation of ARN GABA neurons in healthy females impaired estrous cyclicity, decreased corpora lutea number and increased circulating testosterone levels.
Interpretation
ARN GABA neurons can stimulate the hypothalamic-pituitary axis and chronic activation of ARN GABA neurons can mimic the reproductive deficits of PCOS in healthy females. Unexpectedly blunted HPG axis responses in PNA mice may reflect a history of high frequency GnRH/LH secretion and reduced LH stores, but also raise questions about impaired function within the ARN GABA population and the involvement of other circuits.
It is becoming clear that epigenetic modifications such as DNA methylation can be dynamic and, in many cases, reversible. Here we investigated the photoperiod and hormone regulation of DNA methylation in testes, ovaries, and uterine tissue across multiple time scales. We hypothesized that DNA methyltransferase 3a (dnmt3a) is driven by photoperiodic treatment and exhibits natural variation across the female reproductive cycle and that melatonin increases whereas estrogen reduces DNA methylation. We used Siberian hamsters (Phodopus sungorus) due to their robust changes in reproductive physiology across seasonal and estrus time scales. Our findings indicate that short-day (SD) winter-like conditions significantly increased global DNA methylation and dnmt3a expression in the testes. Using immunohistochemistry, we confirm that increased dnmt3a expression was primarily localized to spermatogonium. Conversely, the ovaries did not exhibit variation in DNA methylation or dnmt3a/3b expression. However, exposure to SD significantly increased uterine dnmt3a expression. We then determined that dnmt3a was significantly decreased during the estrus stage. Next, we ovariectomized females and subsequently identified that a single estrogen+progesterone injection was sufficient to rapidly inhibit dnmt3a and dnmt3b expression. Finally, we demonstrate that treatment of human embryonic kidney-293 cells with melatonin significantly increased both dnmt3a and dnmt3b expression, suggesting that long-duration nocturnal signaling in SD may be involved in the regulation of DNA methylation in both sexes. Overall, our data indicate that dnmt3a shows marked photoperiod and estrus plasticity that likely has broad downstream effects on the timing of the genomic control of reproductive function.
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