Exercise-induced myokines downregulates the ACE2 level in bronchial epithelial cells: Implications for SARS-CoV-2 prevention

Background

The Covid-19 pandemic has emerged as the leading public health challenge of our time (20^th century). While vaccinations have finally blunted the death rate, concern has remained about more virulent forms highlighting the need for alternative approaches. Epidemiological studies indicate that physical activity has been shown to decrease the risk of infection of some respiratory viruses. Part of the salutary effects of exercise is believed to be through the elaboration of cytokines by contracting skeletal muscles (termed myokines). The objective of this study was to investigate whether exercise-induced myokines would mitigate the SARS-CoV-2 infectivity of the bronchial epithelium through modulating the SARS-CoV-2 Covid-19 receptor (angiotensin-converting enzyme 2 -ACE2) its priming enzyme, transmembrane serine protease 2 (TMPRSS2).

Methods

We utilized a cell culture model of exercise to generate myokines by differentiating C2C12 cells into myotubules and inducing them to contract via low-frequency electric pulse stimulation. Condition media was concentrated via centrifugation and applied to human immortalized human bronchial epithelium cell line (6HBE14o) along with conditioned media from unstimulated myotubules as controls. Following exposure to myokines, the 16HBE14o cells were harvested and subjected to quantitative RT-PCR and Enzyme-Linked Immunosorbent Assay (ELISA) for assessment of mRNA and protein levels of ACE2 and TMPRSS2, respectively. Pilot proteomic data was performed with isotope barcoding and mass spectroscopy.

Results

Quantitative Real-Time PCR of 16HBE14o with 48 h treated unstimulated vs. stimulated myokine treatment revealed a reduction of ACE2 and TMPRSS2 mRNA by 32% (p<2.69x10^-5) and 41% (p<4.57x10^-5), respectively. The high sensitivity of ELISAs showed downregulation of ACE2 and TMPRSS2 protein expression in 16HBE14o cells by 53% (p<0.01) and 32% (p<0.03) respectively with 48 h treated. For rigor, this work was replicated in the human lung cancer cell line A549, which mirrored the downregulation. Proteomic analysis showed dramatic alteration in myokine profile between contracted and uncontracted C2C12 tubules.

Conclusions

The current study explores a novel approach of a modified exercise cell culture system and uses ACE2 and TMPRSS2 as a surrogate marker of SARS-CoV-2 infectivity. In conclusion, we demonstrated biological data supporting exercise’s protective effect against Covid-19. These further strengthen myokines’ beneficial role as potential therapeutic targets against SARS-CoV-2 and similar viruses albeit these preliminary cell culture studies will require future validation in animal models.

Abstract C036: Cohesins and colorectal cancer (CRC): Modulation of CRC stem cells and chemoresistance by STAG1 with race-specific implications

Despite advances in treatment and early detective measures for colorectal cancer (CRC), African-Americans (AAs) suffer disproportionately from CRC (~25% higher incidence and ~50% higher mortality) than Caucasians. Furthermore, AAs tend to receive earlier diagnoses in CRC and AA CRCs with high-grade differentiation were 3xs more likely to die within 5 yrs post-surgery as compared to whites (Alexander et al., Cancer 2005). The underlying mechanisms behind this more aggressive disease in AAs are poorly understood. Tomassati and Vogelstein postulate stem cell division correlates with risk of cancer (Science 2015). Addressing disease progression/aggressiveness, CRC stem cell markers are linked to chemoresistance; stem cell markers LGR5 and ALDH1a are established CRC stem cell markers. We have shown that the cohesin family member STAG1, a chromatin remodeler, is lost in the colonic epithelium of patients with premalignant lesions and AAs had a more profound loss (Cancer Prev Research 2016) through AA-specific STAG1 SNPs (Neoplasia 2018) and hypothesize that STAG1 loss is associated with poorer prognosis. Therefore, we wanted to investigate if STAG1 loss may lead to CRC stem cell induction as a potential mechanism of the racial disparities in CRC. RNA from rectal biopsies from 100 patients undergoing screening colonoscopies was processed for real-time PCR for CRC stem cell markers LGR5 and ALDH1a, as well as STAG1. To determine chemoresistance, STAG1 siRNA was transfected in CRC cell line HT29 and a CRISPR transfection of STAG1 SNP rs34149860 (found only in AAs) was transfected in CRC cell line RKO (possessing wildtype to SNP). Cell were treated with 5-FU and oxaliplatin and subjected to Annexin V Assay. Real-time PCR and analysis of STAG1 and CRC stem cell markers were performed for causation. AAs harboring neoplasias displayed a more robust loss of STAG1 mRNA (~50%, p&lt;0.007) vs Caucasians with neoplasias (~25%, p=0.1). In regard to CRC stem cell markers, AAs with adenomas showed a stronger increase of LGR5 (67%, p=0.14), and ALDH1a (73%, p&lt;0.007) vs Caucasians with neoplasias (LGR5 increased 59%, p=0.2; ALDH1a increased ~47%, p&lt;0.05). HT29 cells transfected with STAG1 siRNA showed 30% less apoptotic response to 5-FU vs scramble vector and a marked 74% less response with oxaliplatin. CRIPSR SNP transfection in RKO showed similar effects, with a 2-fold less apoptotic response to 5-FU and &gt;90% less response to oxaliplatin. PCR showed RKO STAG1-SNP transfected cells displayed a loss of STAG1(~40%, p&lt;0.05) and an upregulation of LGR5 (~50%, p&lt;0.05) and ALDH1a (~30%, p&lt;0.05). This shows, for the first time, that STAG1 loss is implicated in colon carcinogenesis through potentiation of cancer stem cells through early carcinogenesis/initiation as well as disease progression and aggressiveness as shown through chemoresistance. Our work provides a potential mechanism in CRC, thus providing a biomarker for cancer screening and therapeutics that could mitigate the racial disparity of CRC in AAs.

Citation Format: Mart Dela Cruz, Caroline Zaworski, Somenath Datta, Sanjib Chowdhury, Hemant K. Roy. Cohesins and colorectal cancer (CRC): Modulation of CRC stem cells and chemoresistance by STAG1 with race-specific implications [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr C036.

Abstract 2562: Stromal antigen 1 (SA1) as a potential pro-neoplastic factor in non-small-cell lung cancer (NSCLC)

Introduction:

SA1, encoded by the STAG1 gene, is a subunit of the higher-order chromatin remodeler cohesin. SA1 deficiency has been implicated as a driver of aneuploidy and tumorigenesis (Remeseiro et al, EMBO J 2012). Furthermore, our lab has recently shown that SA1 functions as a tumor suppressor protein in early colon cancer (Wali et al, Cancer Prev Res 2016). The aim of this project was to investigate the role of SA1 in NSCLC. Combining data from The Cancer Genome Atlas (TCGA), human lung tissue, and in vitro gene knockdown, we have surprisingly identified SA1 as a potential pro-neoplastic factor in NSCLC.

Methods:

Data was extracted from TCGA and plotted to characterize STAG1 gene alteration in NSCLC. Immunohistochemistry (IHC) was performed on human lung tissue microarray assay (TMA) to assess SA1 protein expression. Transient knockdowns were performed on A549 human lung adenocarcinoma cells using STAG1 siRNA (Dharmacon) with an incubation time of 48 hours. Following this, quantitative real-time polymerase chain reaction (qPCR, Life Technologies) and WST-1 cell proliferation assays (Promega) were performed as per protocol.

Results:

STAG1 alterations occur in about 3% of lung adenocarcinoma and 17% of lung squamous cell carcinoma. Of these alterations, the majority were amplifications. Furthermore, although not reaching statistical significance, there was a trend towards decreased survival with STAG1 alteration in adenocarcinoma patients (11.6 months vs. 46 months). IHC demonstrated a 1.7-fold increase in SA1 protein expression in NSCLC when compared with non-malignant lung tissue (p&lt;0.001). Transfected A549 cells showed a 78% decrease in SA1 RNA expression (qPCR, p=0.0002) and a 50% decrease in cell proliferation (WST-1, p&lt;0.0001). Proliferating cell nuclear antigen (PCNA), a marker of cell proliferation, was also decreased by 37% in transfected cells (p&lt;0.001).

Conclusions:

Using TCGA data, we found that STAG1 alteration occurs with some frequency in NSCLC and that many of these alterations are amplifications of the gene. Furthermore, there is a trend towards decreased survival with a STAG1 gene alteration. Our IHC data shows robust over-expression of SA1 in NSCLC when compared with non-malignant lung tissue. Our qPCR data showed a profound decrease in SA1 mRNA expression following transfection; accordingly, our WST-1 proliferation data suggests that knockdown of the STAG1 gene significantly decreases proliferation of A549 lung adenocarcinoma cells. Decreased PCNA confirms a true anti-proliferative effect, rather than a pro-apoptotic effect. This novel data suggests a link between SA1 and NSCLC, of which there are no prior published accounts. Even more compelling is the implication that in NSCLC, SA1 may be pro-neoplastic rather than anti-neoplastic, which introduces a new potential target for future gene therapy.

Citation Format: Michelle Zhang, Mart Dela Cruz, Navneet Momi, Sanjib Chowdhury, Hemant Roy, Adam Lerner. Stromal antigen 1 (SA1) as a potential pro-neoplastic factor in non-small-cell lung cancer (NSCLC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2562. doi:10.1158/1538-7445.AM2017-2562

Higher Order Chromatin Modulator Cohesin SA1 Is an Early Biomarker for Colon Carcinogenesis: Race-Specific Implications

Alterations in high order chromatin, with concomitant modulation in gene expression, are one of the earliest events in the development of colorectal cancer. Cohesins are a family of proteins that modulate high-order chromatin, although the role in colorectal cancer remains incompletely understood. We, therefore, assessed the role of cohesin SA1 in colorectal cancer biology and as a biomarker focusing in particular on the increased incidence/mortality of colorectal cancer among African-Americans. Immunohistochemistry on tissue arrays revealed dramatically decreased SA1 expression in both adenomas (62%; P = 0.001) and adenocarcinomas (75%; P = 0.0001). RT-PCR performed in endoscopically normal rectal biopsies (n = 78) revealed a profound decrease in SA1 expression in adenoma-harboring patients (field carcinogenesis) compared with those who were neoplasia-free (47%; P = 0.03). From a racial perspective, colorectal cancer tissues from Caucasians had 56% higher SA1 expression than in African-Americans. This was mirrored in field carcinogenesis where healthy Caucasians expressed more SA1 at baseline compared with matched African-American subjects (73%; P = 0.003). However, as a biomarker for colorectal cancer risk, the diagnostic performance as assessed by area under ROC curve was greater in African-Americans (AUROC = 0.724) than in Caucasians (AUROC = 0.585). From a biologic perspective, SA1 modulation of high-order chromatin was demonstrated with both biophotonic (nanocytology) and chromatin accessibility [micrococcal nuclease (MNase)] assays in SA1-knockdown HT29 colorectal cancer cells. The functional consequences were underscored by increased proliferation (WST-1; P = 0.0002, colony formation; P = 0.001) in the SA1-knockdown HT29 cells. These results provide the first evidence indicating a tumor suppressor role of SA1 in early colon carcinogenesis and as a risk stratification biomarker giving potential insights into biologic basis of racial disparities in colorectal cancer. Cancer Prev Res; 9(11); 844-54. ©2016 AACR.

Colonic mucosal fatty acid synthase as an early biomarker for colorectal neoplasia: modulation by obesity and gender

BACKGROUND

We have previously reported that colonic pericryptal microvascular blood flow is augmented in the premalignant colonic epithelium, highlighting the increased metabolic demand of the proliferative epithelium as a marker of field carcinogenesis. However, its molecular basis is unexplored. In this study, we assessed the expression of a regulator of the "lipogenic switch," fatty acid synthase (FASN), in early colon carcinogenesis for its potential biomarker utility for concurrent neoplasia.

METHODS

FASN expression (IHC) in the colonic epithelium from azoxymethane and polyposis in rat colon (Pirc) models of colorectal cancer was studied. FASN mRNA expression from endoscopically normal rectal mucosa was evaluated and correlated with colonoscopic findings (pathologic confirmation of neoplasia).

RESULTS

FASN expression progressively increased from premalignant to malignant stage in the azoxymethane model (1.9- to 2.5-fold; P < 0.0001) and was also higher in the adenomas compared with adjacent uninvolved mucosa (1.8- to 3.4-fold; P < 0.001) in the Pirc model. Furthermore, FASN was significantly overexpressed in rectal biopsies from patients harboring adenomas compared with those with no adenomas. These effects were accentuated in male (∼2-fold) and obese patients (1.4-fold compared with those with body mass index < 30). Overall, the performance of rectal FASN was excellent (AUROC of 0.81).

CONCLUSIONS

FASN is altered in the premalignant colonic mucosa and may serve as a marker for colonic neoplasia present elsewhere. The enhanced effects in men and obesity may have implications for identifying patient subgroups at risk for early-onset neoplasia.

IMPACT

These findings support the role of rectal FASN expression as a reliable biomarker of colonic neoplasia.

Buccal microRNA dysregulation in lung field carcinogenesis: gender-specific implications

MicroRNAs (miRNAs) have been shown to be reliable early biomarkers in a variety of cancers including that of lung. We ascertained whether the biomarker potential of miRNAs could be validated in microscopically normal and easily accessible buccal epithelial brushings from cigarette smokers as a consequence of lung cancer linked ‘field carcinogenesis’. We found that compared to neoplasia-free subjects, a panel of 68 miRNAs were upregulated and 3 downregulated in the normal appearing buccal mucosal cells collected from patients harboring lung cancer (n=76). The performance characteristics of selected miRNAs (with ≥1-fold change) were excellent with an average under the receiver operator characteristic curve (AUROC) of >0.80. Several miRNAs also displayed gender specificity between the groups. These results provide the first proof-of-concept scenario in which minimally intrusive cheek brushings could provide an initial screening tool in a large at-risk population.

Nanoscale changes in chromatin organization represent the initial steps of tumorigenesis: a transmission electron microscopy study

Background

Nuclear alterations are a well-known manifestation of cancer. However, little is known about the early, microscopically-undetectable stages of malignant transformation. Based on the phenomenon of field cancerization, the tissue in the field of a tumor can be used to identify and study the initiating events of carcinogenesis. Morphological changes in nuclear organization have been implicated in the field of colorectal cancer (CRC), and we hypothesize that characterization of chromatin alterations in the early stages of CRC will provide insight into cancer progression, as well as serve as a biomarker for early detection, risk stratification and prevention.

Methods

For this study we used transmission electron microscopy (TEM) images of nuclei harboring pre-neoplastic CRC alterations in two models: a carcinogen-treated animal model of early CRC, and microscopically normal-appearing tissue in the field of human CRC. We quantify the chromatin arrangement using approaches with two levels of complexity: 1) binary, where chromatin is separated into areas of dense heterochromatin and loose euchromatin, and 2) grey-scale, where the statistics of continuous mass-density distribution within the nucleus is quantified by its spatial correlation function.

Results

We established an increase in heterochromatin content and clump size, as well as a loss of its characteristic peripheral positioning in microscopically normal pre-neoplastic cell nuclei. Additionally, the analysis of chromatin density showed that its spatial distribution is altered from a fractal to a stretched exponential.

Conclusions

We characterize quantitatively and qualitatively the nanoscale structural alterations preceding cancer development, which may allow for the establishment of promising new biomarkers for cancer risk stratification and diagnosis. The findings of this study confirm that ultrastructural changes of chromatin in field carcinogenesis represent early neoplastic events leading to the development of well-documented, microscopically detectable hallmarks of cancer.

End-binding protein 1 (EB1) up-regulation is an early event in colorectal carcinogenesis

End-binding protein (EB1) is a microtubule protein that binds to the tumor suppressor adenomatous polyposis coli (APC). While EB1 is implicated as a potential oncogene, its role in cancer progression is unknown. Therefore, we analyzed EB1/APC expression at the earliest stages of colorectal carcinogenesis and in the uninvolved mucosa ("field effect") of human and animal tissue. We also performed siRNA-knockdown in colon cancer cell lines. EB1 is up-regulated in early and field carcinogenesis in the colon, and the cellular/nano-architectural effect of EB1 knockdown depended on the genetic context. Thus, dysregulation of EB1 is an important early event in colon carcinogenesis.

Structures of the preantennal region of several species of Damalinia (Phthiraptera: Trichodectidae)

A comparative study was made of the structures of the preantennal region of nine species of Damalinia Mjöberg, 1910 (Phthiraptera: Trichodectidae). Variability in the form of the head, ventral carina, pulvinus, mandibles, and labrum was observed by light and scanning electron microscopy. According to previous studies, the form of the head is possibly influenced by the density and texture of the hair of the host. The ventral carina, which maybe sharp or blunt, and the pulvinus, a membranous lobe, of these parasite species of different hosts, were studied. Photographs of the mandibles and labrum show a high variability according to species.

Superoxide dismutase (SOD) and neutrophil infiltration in intestinal ischaemia-revascularization

SOD is the main detoxifying enzyme of OFRs which have been mainly purported to participate in ischaemia revascularization lesions. A study was made of the behaviour of SOD during ischaemia and the response to pharmacological doses of SOD in Wistar rats in which ischaemia was induced by 90 min of clamping and followed by revascularization. SOD levels were determined in the intestinal wall, evaluating the degree of infiltration of neutrophils, leucocytes and monocytes by immunohistochemical methods. Ischaemia led to a significant decrease in intestinal wall SOD levels (p = 0.003). The administration of pharmacological doses of SOD was observed to improve survival of the animals (p = 0.001) and significantly decreased the infiltration of leucocytes only during revascularization measured by MPO and LCA. Beneficial effects of SOD could be explained by its effect as scavenger of OFRs and by its action on the neutrophil infiltration.

Veratridine-stimulated central synapses in culture: a quantitative ultrastructural analysis

Synapses in explant cultures of fetal rat neocortex at day 18 in vitro were stimulated by veratridine (10(-4)M) for 20 min. The cultures were subsequently processed for electron microscopy and the synapses were analyzed by quantitative techniques, incorporating set mathematical treatment. The mean values of area, perimeter, and form factor of the presynaptic elements significantly increased following veratridine stimulation, compared to the values of control synapses. The length of the postsynaptic thickening also increased, while synaptic curvature did not change significantly in the veratridine group. A fivefold reduction was observed in the mean number of synaptic vesicles per presynaptic element and in the vesicle-terminal area ratio, following veratridine stimulation. The cytoplasm-terminal area ratio and the occurrence of vacuoles/cisternae significantly increased after veratridine application. Planar measurement of membranes (boundary length) of different presynaptic organelles revealed that the total membrane did not change significantly in the veratridine group. The data indicated an increase in volume and swelling of the pre- and postsynaptic elements, considerable depletion of synaptic vesicles, and preservation of the total presynaptic membrane following veratridine stimulation in nerve tissue culture.