p53, Estrogen, and NK Cells Shape Life and Cancer

There is a hidden symmetry between pregnancy and cancer.

In both, tissues must grow rapidly, blood vessels must expand into new territories, and the body must decide whether to permit or restrain invasion. What determines the difference between a nurturing womb and a growing tumor may lie in how a few molecular players — p53, estrogen receptors, natural killer (NK) cells, and VEGF/FLT1 — coordinate their dance around oxygen, stress, and the extracellular matrix.

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The Signal: p53 Meets Estrogen at the FLT1 Gene

In 2010, a PLOS ONE study by Ciribilli et al. uncovered a remarkable piece of the puzzle.
The researchers found that the FLT1 gene — which encodes VEGFR-1, a receptor that senses vascular growth factors — carries a tiny DNA variation (a promoter SNP) that can create a p53 response element. But here’s the twist: p53 doesn’t act alone. It activates FLT1 only when estrogen receptor α (ERα) is nearby, bound to its own DNA half-sites.

This means that p53, often called the guardian of the genome, cooperates with estrogen signaling to tune the sensitivity of blood vessels to VEGF and PlGF, the key drivers of angiogenesis. The study also showed that this activation happens after genotoxic stress such as doxorubicin, but not after other DNA-damaging agents like 5-fluorouracil, underscoring how specific the stress context must be.

In parallel, hypoxia — low oxygen levels — can activate the same FLT1 promoter through HIF-1α. Under these conditions, tissues produce not only the full receptor FLT1 but also its soluble form (sFlt-1), which soaks up VEGF and PlGF like a sponge. It’s a perfect tuning mechanism: too much sFlt-1, and angiogenesis is blocked; too little, and blood vessels grow unchecked.

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The Uterine Parallel: The Angiogenic Flood

A decade later, this molecular logic finds a physiological echo in early pregnancy. In The Angiogenic Growth Factor Flood, I explored how natural killer (NK) cells in the uterine lining (the decidua) create a surge of angiogenic growth factors just before and during implantation.

These decidual NK (dNK) cells express a2V-ATPase, acidifying the extracellular matrix and activating MMP-9, a powerful enzyme that cuts through collagen and releases growth factors bound within the ECM. The result is a literal flood of VEGF and PlGF — the same molecules p53 and ERα regulate through FLT1 expression.

Independent research confirms this choreography. During the first trimester, dNK cells secrete VEGF-C, PlGF, Angiopoietin-1/2, and MMP-2/-9, guiding spiral artery remodeling — the vital widening of maternal arteries that ensures proper blood flow to the placenta (Sojka et al., Frontiers in Immunology 2022). If this process falters, preeclampsia can develop, a condition marked by shallow invasion, high vascular resistance, and — notably — elevated sFlt-1 levels in maternal blood (Levine et al., NEJM 2004).

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Two Layers, One Circuit

Taken together, these findings reveal a single two-layered circuit:

1. The receptor layer –
   p53, ERα, and HIFs determine how much FLT1/sFlt-1 the tissue expresses, setting its sensitivity to VEGF and PlGF.

2. The matrix layer –
   NK cells and trophoblasts remodel the ECM via a2V-ATPase and MMP-9, controlling the availability of those same VEGF and PlGF molecules.

When these layers synchronize, arterial remodeling proceeds smoothly: arteries dilate, resistance drops, and the embryo receives life-sustaining flow. When they desynchronize, the results diverge — preeclampsia in pregnancy, or uncontrolled angiogenesis in tumors.

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From the Womb to the Tumor

It’s no coincidence that cancer co-opts the same program. Hypoxic tumor microenvironments stabilize HIF-1α and HIF-2α, driving VEGF and FLT1 expression much like the early placenta. Meanwhile, matrix metalloproteinases (MMPs) — especially MMP-9 — break down ECM barriers and unleash angiogenic factors, supporting invasion and metastasis. Some tumors even enlist NK-like cells that, paradoxically, promote angiogenesis rather than suppress it (Gao et al., Nature Reviews Immunology 2017).

The difference is control. In pregnancy, p53 remains intact but functionally moderated, allowing invasion to stop at the right depth. In cancer, p53 mutations or inactivation remove that restraint, unleashing angiogenesis without limit. Wild-type p53 can also induce thrombospondin-1, an anti-angiogenic protein, and repress VEGF itself (Teodoro et al., Nature Cell Biology 2006). When p53 is lost, that brake disappears.

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Lessons in Balance

The elegance of this system lies in its balance. The sFlt-1/PlGF ratio, now used clinically to predict preeclampsia, captures that equilibrium numerically (Zeisler et al., NEJM 2016). Too much soluble receptor, and the flood is dammed; too little, and angiogenesis runs wild.

The parallels between the placenta and the tumor remind us that biology reuses its best designs — sometimes for creation, sometimes for destruction. Both depend on oxygen gradients, immune-matrix crosstalk, and the nuanced cooperation of p53, ERα, HIFs, and NK-cell proteases.

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Looking Ahead

Understanding this unified circuit opens therapeutic possibilities on both fronts:

• In obstetrics, modulating the sFlt-1/PlGF balance and supporting healthy NK/trophoblast-matrix signaling may prevent or reverse preeclampsia.

• In oncology, restoring p53 function, adjusting ER context, or tempering HIF-driven FLT1 and MMP-9 activity could re-normalize tumor vasculature.

• In both, recognizing NK cells as angiogenic regulators — not just killers — reframes how immune therapy and vascular therapy intersect.

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Further Reading

• The Coordinated p53 and Estrogen Receptor Cis-Regulation at an FLT1 Promoter SNP — PLOS ONE (2010)

• The Angiogenic Growth Factor Flood — Codondex Blog (2022)

• Sojka et al., Front Immunol 2022 – Uterine NK cells and spiral artery remodeling

• Levine et al., NEJM 2004 – sFlt-1 and PlGF in preeclampsia

• Zeisler et al., NEJM 2016 – sFlt-1/PlGF ratio for preeclampsia prediction

• Teodoro et al., Nat Cell Biol 2006 – p53 repression of VEGF via thrombospondin-1

• Gao et al., Nat Rev Immunol 2017 – NK cells in angiogenesis and cancer

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Inflammation and Stretch: Mechanics of Immunity Meet at p53

We often picture inflammation as a storm of cytokines — TNF-α, IL-6, interferons — released by immune cells. But inflammation is more than chemistry: it reshapes mechanics at the cellular and tissue level resulting in stiffening blood vessels, increasing vascular tone, and causing edema. Inflammation forces tissues into stretch and strain (Pober & Sessa, 2007: ; Schiffrin, 2014:).

Cells sense this stretch as stress. Endothelial and smooth muscle cells don’t simply absorb it — they activate protective and inflammatory pathways. At the crossroads of this response is p53, the well-known “guardian of the genome,” which here becomes a translator of mechanical stress into immune tone.

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Inflammation Creates Stretch

At the onset of inflammation, immune cells like neutrophils and macrophages release cytokines (TNF-α, IL-1β, IL-6) and reactive oxygen species. These trigger several physical consequences:

• Vasoconstriction: cytokines reduce nitric oxide and increase endothelin-1, raising intravascular pressure (Virdis & Schiffrin, 2003:).

• Edema: increased vascular permeability leads to tissue swelling, compressing vessels from the outside (Ley et al., 2007:).

• Stiffening: macrophages and T cells drive fibrosis through collagen deposition and TGF-β, making vessel walls less compliant (Intengan & Schiffrin, 2000:).

Together, these changes simulate mechanical stretch at the microvascular level.

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Stretch Activates p53

Mechanical strain is known to activate p53 through oxidative stress, DNA damage responses, and ER stress (Madrazo & Kelly, 2008:). In vascular cells:

• Endothelial cells: p53 can reduce IL-6 (by competing with NF-κB) but enhance interferon signaling (via STAT1/IRF9) (Vousden & Prives, 2009:).

• Smooth muscle cells: p53 drives cell cycle arrest and senescence, stabilizing the vessel wall but promoting stiffness (Giaccia & Kastan, 1998:).

• Immune cells (including NK cells): p53 regulates survival, apoptosis, and cytokine output, balancing activation against exhaustion (Menendez et al., 2009:).

Thus, p53 acts as a convergence point where inflammation-induced mechanics meet immune regulation.

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NK Cells: Partners in the Loop

Natural killer (NK) cells illustrate how mechanics and immunity are intertwined.

• Early NK response (hours to day 1): NKs are rapidly recruited by cytokines and stress ligands, releasing IFN-γ and TNF-α, and injuring stressed endothelial cells. Here, p53 activity in vascular cells biases the environment toward interferon signaling, supporting NK activation (Vivier et al., 2011:).

• Transition phase (days): macrophages and dendritic cells dominate, producing IL-6 and TNF-α. p53 in these myeloid cells restrains NF-κB–driven cytokines while promoting type I interferons, further priming NK cells (Sakaguchi et al., 2020:).

• Late NK response (days–weeks): NKs amplify chronic inflammation through IFN-γ, TNF-α, and antibody-dependent cytotoxicity. In this phase, p53 may push NKs toward exhaustion, while senescent endothelial and smooth muscle cells release SASP factors (IL-6, IL-8) that perpetuate the cycle (Coppe et al., 2010:).

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The Feedback Loop

Inflammation and stretch are not separate. They form a self-reinforcing loop:

1. Inflammation → Stretch: cytokines alter vascular tone, stiffness, and permeability.

2. Stretch → p53 activation: p53 senses the stress in endothelial, smooth muscle, and NK cells.

3. p53 → Immune tone: restrains IL-6, enhances interferons, and modulates NK cell survival and cytokine balance.

4. NK cells → More inflammation: IFN-γ and TNF-α amplify vascular injury and immune recruitment.

This cycle explains why hypertension, vascular inflammation, and immune activation are so tightly linked.

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Why It Matters

Understanding how inflammation leads to mechanical stress, and how p53 links stretch to immunity, may open therapeutic opportunities:

• Reducing vascular stiffness could break the loop between mechanics and inflammation.

• Modulating p53 might rebalance cytokine outputs (lowering IL-6 while supporting interferons).

• Preserving NK cell function under stress could sustain protective immunity without driving exhaustion.

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🔑 Takeaway: Inflammation doesn’t just signal with cytokines — it also stretches tissues. This stretch activates p53, which reshapes the immune response, especially in NK cells. Together they form a loop where mechanics and immunity reinforce one another in health and disease.

Cancer and The PEPCK Clutch!

Key Points

• Research suggests mediated mechanical stretch can mimic localized increases in blood pressure and inflammation, based on studies showing stretch affects vascular cells and induces inflammatory responses.

• It seems likely that PEPCK, an enzyme involved in metabolism, can be induced to support a metabolic cell state that promotes outcomes like prolonged cell life and disease, especially in cancer, where it supports cell survival under stress.

• The evidence leans toward mechanical stretch influencing cancer cell metabolism, potentially involving PEPCK, though direct links need further study.

Background

Mediated mechanical stretch refers to controlled mechanical forces applied to cells or tissues, often used in lab settings to simulate physiological conditions like increased blood pressure. This can affect how cells behave, particularly in blood vessels and potentially in cancer. PEPCK, or Phosphoenolpyruvate Carboxykinase, is an enzyme key to gluconeogenesis, the process of making glucose from non-carbohydrate sources, and is notably active in cancer cells under nutrient stress.

Connection to Blood Pressure and Inflammation

Studies show mechanical stretch can mimic conditions of high blood pressure and inflammation. For instance, stretch on vascular cells increases reactive oxygen species and inflammation markers, similar to what happens with hypertension (Mechanical stretch: physiological and pathological implications for human vascular endothelial cells). This suggests stretch can create a microenvironment akin to diseased states.

Role of PEPCK in Disease

PEPCK is crucial in cancer, where it helps cells survive by altering metabolism under stress, such as low glucose. Research indicates PEPCK supports cancer cell growth by enhancing glucose and glutamine use, potentially prolonging cell life and promoting disease progression (PEPCK coordinates the regulation of central carbon metabolism to promote cancer cell growth).

Linking Mechanical Stretch and PEPCK

While direct studies linking mechanical stretch to PEPCK in cancer are limited, the connection seems plausible. Mechanical stretch can induce inflammation and metabolic changes, and in cancer, this could upregulate PEPCK, supporting a cell state that aligns with prolonged survival and disease promotion. This is an unexpected detail, as stretch is often seen as beneficial (e.g., exercise), but here it may exacerbate cancer conditions.

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Survey Note: Detailed Analysis of Mechanical Stretch, PEPCK, and Disease Promotion

This section provides a comprehensive exploration of the user's query, examining the potential for mediated mechanical stretch to mimic localized increases in blood pressure and inflammation, and whether PEPCK can be induced to support a metabolic cell state promoting outcomes that prolong cell life and promote disease. The analysis draws on various studies and blog posts referenced, ensuring a thorough understanding for readers with a scientific background.

Understanding Mediated Mechanical Stretch

Mediated mechanical stretch involves applying controlled mechanical forces to cells or tissues, often to simulate physiological or pathological conditions. Research indicates that such stretch can replicate the effects of increased blood pressure and inflammation at a localized level. For example, a study on vascular endothelial cells showed that mechanical stretch, especially under conditions mimicking hypertension, leads to the formation of reactive oxygen species and inflammation, aligning with pathological consequences (Mechanical stretch: physiological and pathological implications for human vascular endothelial cells). Another study, "The Effect of Pressure-Induced Mechanical Stretch on Vascular Wall Differential Gene Expression" (The Effect of Pressure-Induced Mechanical Stretch on Vascular Wall Differential Gene Expression), further supports that stretch can induce gene expression changes similar to those seen in high blood pressure, validating the user's premise.

Blood Pressure and Inflammation: Detailed Mechanisms

The connection between mechanical stretch and blood pressure is evident in studies showing stretch affects arterial stiffness and blood pressure regulation. For instance, regular stretching exercises have been shown to reduce blood pressure in hypertensive patients, suggesting a link between mechanical forces and vascular responses (Compliance of Static Stretching and the Effect on Blood Pressure and Arteriosclerosis Index in Hypertensive Patients). Inflammation is also induced by stretch, as seen in studies where cyclic mechanical stretch upregulates pro-inflammatory pathways, particularly in vascular smooth muscle cells, contributing to conditions like chronic venous insufficiency (The Effect of Pressure-Induced Mechanical Stretch on Vascular Wall Differential Gene Expression).

A detailed breakdown of relevant findings is presented in the following table, extracted from blog posts and studies:

Topic	Details	Exact Numbers	Relevant URLs
Mechanical Stretch	Causes sustained molecular signaling of pro-inflammatory and proliferative pathways, tied to p53, occurs in disturbed flow and undirected stretch at branch points and complex regions.	-	journals.physiology.org, blog.codondex.com
Blood Pressure	Meta-analysis of 7017 individuals identified 34 differentially expressed genes, 6 linked to BP and hypertension, MYADM (19q13) the only gene across diastolic, systolic BP, and hypertension.	7017, 34, 6	journals.plos.org, www.ncbi.nlm.nih.gov
Inflammation	Controlled by interaction between plasma membrane and submembrane at endothelial surface; MYADM knockdown induces inflammatory phenotype via ICAM-1 (19p13) increase, mediated by ERM actin cytoskeleton proteins; S1P2 (19p13) involved in immune, nervous, metabolic, cardiovascular, musculoskeletal, renal systems.	-	blog.codondex.com, www.ncbi.nlm.nih.gov, rupress.org, www.ncbi.nlm.nih.gov, www.jimmunol.org, www.ncbi.nlm.nih.gov, onlinelibrary.wiley.com, www.researchgate.net, www.ncbi.nlm.nih.gov, journals.asm.org, journals.plos.org, www.jbc.org, www.gastrojournal.org, www.spandidos-publications.com

This table highlights the molecular and physiological impacts, providing a foundation for understanding how stretch influences blood pressure and inflammation.

PEPCK and Its Role in Metabolic Cell States

PEPCK, or Phosphoenolpyruvate Carboxykinase, is a key enzyme in gluconeogenesis, converting oxaloacetate to phosphoenolpyruvate. Its role extends beyond normal physiology into cancer, where it supports metabolic flexibility under nutrient stress. Studies show PEPCK, particularly the mitochondrial isoform PCK2, is expressed in lung and other cancer tissues, aiding cell survival by enhancing glucose and glutamine utilization (PEPCK in cancer cell starvation). This metabolic adaptation can prolong cell life, especially in cancer, and promote disease progression by supporting tumor growth (PEPCK coordinates the regulation of central carbon metabolism to promote cancer cell growth).

Linking Mechanical Stretch, PEPCK, and Disease Promotion

The user's query posits whether PEPCK can be induced to support a single metabolic cell state that promotes outcomes similar to those from mechanical stretch, which mimics increased blood pressure and inflammation, and whether this prolongs cell life and promotes disease. While direct studies linking mechanical stretch to PEPCK induction are scarce, indirect evidence suggests a connection. Mechanical stretch induces inflammation and alters glucose metabolism, as seen in skeletal muscle studies where stretch increases glucose uptake via ROS and AMPK pathways (Stretch-stimulated glucose uptake in skeletal muscle is mediated by reactive oxygen species and p38 MAP-kinase). In cancer, where inflammation is a known promoter, mechanical stretch could create a microenvironment that upregulates PEPCK, supporting a metabolic state conducive to prolonged cell survival and disease, particularly in tumors under stress.

For instance, a study on lung cancer progression under mechanical stretch highlights its role in tumor microenvironment changes, potentially affecting metabolic pathways (An Overview of the Role of Mechanical Stretching in the Progression of Lung Cancer). Given PEPCK's role in cancer metabolism, it's plausible that such conditions could induce PEPCK, aligning with the user's hypothesis. This is an unexpected detail, as stretch is often viewed positively (e.g., exercise benefits), but here it may exacerbate cancer by supporting a disease-promoting metabolic state.

Conclusion and Implications

Based on the analysis, it seems likely that mediated mechanical stretch, by mimicking localized increases in blood pressure and inflammation, can create conditions where PEPCK is induced to support a metabolic cell state. This state, particularly in cancer, can promote outcomes like prolonged cell life and disease progression, fitting the user's query. Further research is needed to confirm direct links, but the evidence leans toward this possibility, offering insights into how mechanical forces influence cancer metabolism.

Key Citations

• Mechanical stretch: physiological and pathological implications for human vascular endothelial cells

• The Effect of Pressure-Induced Mechanical Stretch on Vascular Wall Differential Gene Expression

• Compliance of Static Stretching and the Effect on Blood Pressure and Arteriosclerosis Index in Hypertensive Patients

• PEPCK in cancer cell starvation

• PEPCK coordinates the regulation of central carbon metabolism to promote cancer cell growth

• Stretch-stimulated glucose uptake in skeletal muscle is mediated by reactive oxygen species and p38 MAP-kinase

• An Overview of the Role of Mechanical Stretching in the Progression of Lung Cancer

Chemo vs. Mecho

Data strongly suggests interaction between plasma membrane and submembrane at the endothelial surface controls the inflammatory response. 

A meta-analysis from six studies of global gene expression profiles of Blood Pressure (BP) and hypertension was performed in 7017 individuals. 34 genes were differentially expressed. Of these, 6 genes were linked including MYADM, which was the only gene, of 34 discovered across diastolic, systolic BP and hypertension. Knockdown of MYADM (19q13), a component of endothelial surface rafts induced an inflammatory phenotype altering barrier function through the increase of the adhesion receptor ICAM-1 (19p13). This is mediated by MYADM activation of ERM actin cytoskeleton proteins. 

Mechanical forces, without a definitive direction e.g., disturbed flow and relatively undirected stretch at branch points and other complex regions cause sustained molecular signaling of pro-inflammatory and proliferative pathways that include mechanical stretch tied to p53. 

ERM proteins also facilitate Sphingosine-1-phosphate (S1P) dependent egress for T-cells to migrate from lymphoid organs. Their directional migration, by blebbing is contained at the T-cell’s leading edge. This fundamentally different mode of migration is characterized by intracellular pressurization. Of the five S1P receptors S1P2 (19p13) is critical in the immune, nervous, metabolic, cardiovascular, musculoskeletal, and renal systems. Results suggest that the ratio between S1P1 and S1P2 (19p13) governs the migratory behavior of different T cell subsets. 

Human NK cells express S1P1 mRNA. Activation with IL-2 increases S1P1, promotes S1P4 (19p13) and S1P5 (19p13) but not S1P2 (19p13) expression. Unlike S1P1, S1P2 (19p13) signals through several different G-alpha subunits, Gi, G12/13, and Gq. S1P5 (19p13) is also expressed in human and mouse NK cells and was required for mobilization to inflamed organs. S1P5-deficient mice had aberrant NK cell homing during steady-state conditions. NK cell trafficking in vivo requires a dedicated sphingosine 1-phosphate receptor. 

Virus-infected mast cells selectively recruit NK cells and positively modulate their functions through mechanisms dependent on soluble mediators, such as interferons. Skin mast cells protect mice against vaccinia virus by triggering mast cell receptor S1P2 (19p13) and releasing antimicrobial peptides. S1P2 (19p13),  a negative regulator of platelet derived growth factor (PDGF) induced migration and proliferation as well as SphK1 expression. 

S1P inhibits macropinocytosis (internalizing extracellular materials) and phosphorylation of Akt via S1P2 (19p13) stimulation resulting in diminished antigen capture.

S1P1, S1P2 (19p13) and S1P3 receptors have redundant or cooperative functions for the development of a stable and mature vascular system during embryonic development. S1P2 (19p13)  and S1P3 are involved in regulation of endothelial barrier function, fibrosis, and vasoconstriction. 

Adipogenic differentiation is inhibited by S1P2 (19p13) as mediated by C/EBPα and PPARγ, which induces PEPCK, a more recent gene of interest in cancer that acts at the junction between glycolysis and the Krebs cycle.

Mecho or chemo, chicken or egg, what first?

Systolic Blood Pressure and Innate Immunity vs. the Cancer Brain

Participants with a valid heart disease phenotype (atherosclerosis) were identified in a MESA blood pressure analysis conducted over 10 years. The valid group varied from 770 to 1113 patients from whom further blood analysis queried a primary and exploratory hypothesis of immune cell subsets. Four statistically significant innate cell subsets were discovered to be associated with Systolic blood pressure (SBP); Natural Killer (NK) cells, gamma delta T cells and classical monocytes.

Separately, an analysis of 7017 individuals from 6 international studies of gene expression signatures for SBP, diastolic blood pressure (DBP) and hypertension (HTN) found 7717 genes of which 34 were most differentialy expressed. Enrichment analysis for the systolic and diastolic gene group's associated to NK cell mediated cytotoxicity and 13 other pathways including antigen processing and inflammatory response, pointing strongly to innate and adaptive immunity. MYADM was the only gene identified for all groups SBP, DBP and HTN.

MYADM controls endothelial barrier function through ezrin, radixin, and moesin (ERM)-dependent regulation of ICAM-1 expression. ERM expression is required for ICAM-1 expression in response to MYADM suppression or TNF-α. ICAM-1 is a paradigmatic adhesion receptor that regulates leukocyte adhesion together with integrin LFA-1. This connection between endothelial membrane and cortical actin cytoskeleton appears to modulate the inflammatory response at the blood tissue barrier. 

Pressure overload activates the sympathetic nervous system (SNS) and up-regulates p53 expression in the cardiac endothelium and in bone marrow (BM) cells. Increased p53 expression promotes endothelial-leukocyte cell adhesion and initiates inflammation in cardiac tissue, which exacerbates systolic dysfunction. SNS activates, at least by significant increase of circulating norepinephrine (NE), which up-regulates p53 expressions, while forced expression of p53 increased ICAM-1 expression. 

On endothelial cells SNS is mediated via catecholamine-β2-adrenergic signaling, which up-regulates the production of reactive oxygen species (ROS), activates p53 and induces cellular senescence. Immune cells, including macrophages, monocytes, NK cells, B and T cells express the β2-adrenergic receptor and catecholamine. During pressure overload, NE cultured macrophages up-regulated p53 expression, whereas introduction of p53 increased Itgal (LFA-1) expression (which binds ICAM-1). Treatment with NE increased ROS, which was attenuated after inhibition of β2- adrenergic signaling in macrophages. Endothelial cell–macrophage interaction via NE-ROS-p53 signaling induces up-regulation of adhesion molecules, thus contributing to cardiac inflammation and systolic dysfunction.

During hypertension the vascular endothelium activates monocytes, in part through ROS by a loss of nitric oxide (NO) signaling, increased release of IL-6, hydrogen peroxide and a parallel increase in STAT activation in adjacent monocytes. NO inhibits formation of intermediate monocytes and STAT3 activation. Humans with hypertension have increased intermediate and non-classical monocytes and  intermediate monocytes demonstrate evidence of STAT3 activation. Mice with experimental hypertension exhibit increased aortic and renal infiltration of monocytes, dendritic cells, and macrophages with activated STAT3.

A senescence-associated secretory phenotype (SASP) was induced in epithelial cells after DNA damage of sufficient magnitude. In premalignant epithelial cells SASPs induced an epithelial–mesenchyme transition and invasiveness, hallmarks of malignancy by a paracrine mechanism that largely depended interleukin (IL)-6 and IL-8. Strikingly, loss of p53 and gain of oncogenic RAS exacerbated the pro-malignant activities. This suggests a cell-non-autonomous mechanism by which p53 can restrain and oncogenic RAS can promote the development of age-related cancer by altering the tissue microenvironment. Oncogenic signaling pathways inhibit the p53 gene transcription rate through a mechanism involving Stat3, which binds to the p53 promoter in vitro and in vivo. Blocking Stat3 in cancer cells up-regulates expression of p53, leading to p53-mediated tumor cell apoptosis. 

Induced stretch or stretch from pressure overload may engage a non-autonomous, p53 centric micro-mechanical mechanism that escalates or deescalates innate responses against cells functioning outside the mechanical ranges that macrophages or NK cells permit. Thus, the neuro-immune extension through SNS signaling, may begin with circulating blood pressure or stretch promoted through inflammation. 

Not Only A Killer A System for Killing!

The next time you're out exercising, spare a thought for your busy mitochondria. NASA scientists just reported mitochondria as the key to health problems in space.

Natural killer (NK) cells can extend membrane probes into cells or pathogens. These are loaded with granulysin (GNLY) to penetrate and perforin (PFN) to kill intracellular bacteria or protozoa and can lyse entire cells. The probes can also transfer healthy mitochondria to apoptotic cardiomyocytes (and other cells) in need of mitochondrial transfer. Uterine NK cells of the decidua send probes into trophoblasts to selectively kill intracellular Listeria monocytogenes without killing the trophoblast host. Stressed cells, moving toward apoptosis can behave similarly, but in reverse shooting out nanoprobes to proximal cells seeking cooperation and urgent mitochondrial transfers including to cancer cells.

A meta-analysis of gene expression signatures for blood pressure and hypertension in 7017 individuals from 6 international studies found of 7717 genes, 34 were most differentialy expressed including GNLY. Enrichment analysis for the diastolic and systolic gene group's associated strongly with NK cell mediated cytotoxicity and 13 other pathways including antigen processing and inflammatory response.

Formation of membrane probes or tubes, in which mitochondria travel and establishment of intracellular mitochondrial networks in the peripheral zone of cells require Kinesin-1 heavy chain (KIF5B). KIF5B is also required for female meiosis (oogenesis) and proper chromosomal segregation in mitotic cells and modulates central spindle organization in late-stage cytokinesis in chondrocytes.

A study of centromere heterochromatin (connected with central spindle) surprisingly showed that distant euchromatic regions, enriched in repressed methylated genes also interacted with the hierarchical organization of centromeric DNA. These 3D spatial interactions (at a distance) are likely mediated by liquid-like fusion events and can influence the health of individuals. Repressed gene's were identified as transposable elements, sequences often associated with pathogenic DNA insertions that have been persistently retained.  

KIF5B is an interaction partner of ADP-ribosylation factor-like 8b (Arl8b), which is required for NK cell–mediated cytotoxicity that drives polarization of lytic granules and microtubule-organizing centers (MTOCs) toward the immune synapse between NK and target cells. Silencing experiments that led to failure of MTOC-lytic granule polarization suggest Arl8b and KIF5B together control the critical step in NK cell cytotoxicity. 

KIF5B is also a critical transporter of p53 and c-Myc to the cytoplasm for degradation. However, subcellular localization of Arl8b and p53-dependent cell death was shown to occur through knockdown of acetylation subunit NatC. As a consequence, p53 is stabilized, phosphorylated and significantly activates transcription of downstream proapoptotic genes. In the absence KIF5B, or presence of  mutants p53 and c-Myc aggregate in the nucleus where they signal DNA damage-induced apoptosis through the control of p53 by endogenous c-Myc (in vivo).

Finely tuned, frequently used KIF5B in NK cells expressing GNLY may induce effects on local tissue blood pressure, as was discovered by expression of Renin-Angiotensin vasoactive proteins AT1, AT2, and ANP in pregnancy-induced uterine NK cells. Inflammation signaling, via tissue bound NK cells may result from stretch-mediated release of angiotensin II, which is coupled with p53 acetylation apoptosis and activation of p53. This may prolong upregulation of the local renin-angiotensin system, increase susceptibility of target cells to apoptosis and signal adaptive immune cells. 

Somewhere in the balance between NatC knockdown induced apoptosis and angiotensin II induced apoptosis p53 may direct traffic to keep your cells healthy!