STAT3 and hypoxia induced proteins--HIF-1alpha, EPO and EPOR in relation with Bax and Bcl-xL in nodal metastases of ductal breast cancers.

STAT3 contributes to increase of EPO expression which is also HIF-1 dependent. EPO receptor activates STAT3. Expressions of STAT3 and hypoxia induced proteins: HIF-1, EPO and EPOR show mutual correlations in primary ductal breast cancers, which suggest co-operation among these proteins. Moreover, EPO-EPOR signaling was reported to mediate cell survival by targeting Bcl-xL in competition with Bax-dependent apoptosis. Our present study was focused on immunohistochemical evaluation of STAT3, HIF-1alpha, EPO and EPOR in relation to apoptosis regulators, Bax and Bcl-xL in 39 metastases of ductal breast cancers to lymph nodes. The proteins were abundantly expressed by cancer cells. HIF-1alpha correlated with EPOR in all and in chemotherapy treated metastases (r=0.428, p=0.007 and r=0.462, p=0.040, respectively). HIF-1 associated significantly with EPO in chemotherapy spared metastases (r=0.549, p=0.015) and comparison between those proteins almost reached statistical significance in entire number of metastatic breast cancers (r=0.309, p=0.056). Metastases from T2 primary tumors had significantly higher expressions of HIF-1alpha, EPO and EPOR compared to T1 originating metastases (p=0.020, p=0.028, p=0.021, respectively). Bax correlated with EPO and EPOR in all studied nodal metastases (r=0.449, p=0.006 and r=0.421, p=0.011, respectively) and so did Bcl-xL with HIF-1alpha (r=0.440, p=0.007), EPO and EPOR (r=0.383, p=0.021, r=0.495, p=0.002, respectively). Metastatic breast cancers seem to be areas of intensive signaling by STAT3, HIF-1, EPO and EPOR. Strong Bax and Bcl-xL labeling reflects accelerated cell turnover in nodal metastases. By means of association with Bcl-xL, HIF-1alpha, EPO and EPOR could favor growth of nodal metastases and survival of breast cancers cells

Addressing the 'hypoxia paradox' in severe COVID-19: literature review and report of four cases treated with erythropoietin analogues

Since fall 2019, SARS-CoV-2 spread world-wide, causing a major pandemic with estimated ~ 220 million subjects affected as of September 2021. Severe COVID-19 is associated with multiple organ failure, particularly of lung and kidney, but also grave neuropsychiatric manifestations. Overall mortality reaches > 2%. Vaccine development has thrived in thus far unreached dimensions and will be one prerequisite to terminate the pandemic. Despite intensive research, however, few treatment options for modifying COVID-19 course/outcome have emerged since the pandemic outbreak. Additionally, the substantial threat of serious downstream sequelae, called 'long COVID' and 'neuroCOVID', becomes increasingly evident. Main body of the abstract Among candidates that were suggested but did not yet receive appropriate funding for clinical trials is recombinant human erythropoietin. Based on accumulating experimental and clinical evidence, erythropoietin is expected to (1) improve respiration/organ function, (2) counteract overshooting inflammation, (3) act sustainably neuroprotective/neuroregenerative. Recent counterintuitive findings of decreased serum erythropoietin levels in severe COVID-19 not only support a relative deficiency of erythropoietin in this condition, which can be therapeutically addressed, but also made us coin the term 'hypoxia paradox'. As we review here, this paradox is likely due to uncoupling of physiological hypoxia signaling circuits, mediated by detrimental gene products of SARS-CoV-2 or unfavorable host responses, including microRNAs or dysfunctional mitochondria. Substitution of erythropoietin might overcome this 'hypoxia paradox' caused by deranged signaling and improve survival/functional status of COVID-19 patients and their long-term outcome. As supporting hints, embedded in this review, we present 4 male patients with severe COVID-19 and unfavorable prognosis, including predicted high lethality, who all profoundly improved upon treatment which included erythropoietin analogues. Short conclusion Substitution of EPO may among other beneficial EPO effects in severe COVID-19 circumvent downstream consequences of the 'hypoxia paradox'. A double-blind, placebo-controlled, randomized clinical trial for proof-of-concept is warranted