Genomic Features of Homologous Recombination Deficiency in Breast Cancer: Impact on Testing and Immunotherapy.

Genomic instability is one of the well-established hallmarks of cancer. The homologous recombination repair (HRR) pathway plays a critical role in correcting the double-stranded breaks (DSB) due to DNA damage in human cells. Traditionally, the BRCA1/2 genes in the HRR pathway have been tested for their association with breast cancer. However, defects in the HRR pathway (HRD, also termed 'BRCAness'), which has up to 50 genes, have been shown to be involved in tumorigenesis and treatment susceptibility to poly-ADP ribose polymerase inhibitors (PARPis), platinum-based chemotherapy, and immune checkpoint inhibitors (ICIs). A reliable consensus on HRD scores is yet to be established. Emerging evidence suggests that only a subset of breast cancer patients benefit from ICI-based immunotherapy. Currently, albeit with limitations, the expression of programmed death-ligand 1 (PDL1) and tumor mutational burden (TMB) are utilized as biomarkers to predict the favorable outcomes of ICI therapy in breast cancer patients. Preclinical studies demonstrate an interplay between the HRR pathway and PDL1 expression. In this review, we outline the current understanding of the role of HRD in genomic instability leading to breast tumorigenesis and delineate outcomes from various clinical trials. Furthermore, we discuss potential strategies for combining HRD-targeted therapy with immunotherapy to achieve the best healthcare outcomes in breast cancer patients.

Food Waste from Campus Dining Hall as a Potential Feedstock for 2,3-Butanediol Production via Non-Sterilized Fermentation.

Food waste is a major issue that is increasingly affecting our environment. More than one-third of food is wasted, resulting in over $400 billion in losses to the U.S. economy. While composting and other small recycling practices are encouraged from person-to-person, it is not enough to balance the net loss of 80 million tons per year. Currently, one of the most promising routes for reducing food waste is through microbial fermentation, which can convert the waste into valuable bioproducts. Among the compounds produced from fermentation, 2,3-butanediol (2,3-BDO) has gained interest recently due to its molecular structure as a building block for many other derivatives used in perfumes, synthetic rubber, fumigants, antifreeze agents, fuel additives, and pharmaceuticals. Waste feedstocks, such as food waste, are a potential source of renewable energy due to their lack of cost and availability. Food waste also possesses microbial requirements for growth such as carbohydrates, proteins, fats, and more. However, food waste is highly inconsistent and the variability in composition may hinder its ability to be a stable source for bioproducts such as 2,3-BDO. This current study focuses specifically on post-consumer food waste and how 2,3-BDO can be produced through a non-model organism, Bacillus licheniformis YNP5-TSU during non-sterile fermentation. From the dining hall at Tennessee State University, 13 food waste samples were collected over a 6-month period and the compositional analysis was performed. On average, these samples consisted of fat (19.7%), protein (18.7%), ash (4.8%), fiber (3.4%), starch (27.1%), and soluble sugars (20.9%) on a dry basis with an average moisture content of 34.7%. Food waste samples were also assessed for their potential production of 2,3-BDO during non-sterile thermophilic fermentation, resulting in a max titer of 12.12 g/L and a 33% g/g yield of 2,3-BDO/carbohydrates. These findings are promising and can lead to the better understanding of food waste as a defined feedstock for 2,3-BDO and other fermentation end-products.

Complex Role of Microbiome in Pancreatic Tumorigenesis: Potential Therapeutic Implications.

Pancreatic cancer (PC) is the fourth leading cause of cancer-related mortality with limited diagnostic and therapeutic options. Although immunotherapy has shown promise in the treatment of several cancers, its role in pancreatic cancer is rather limited. Several studies have focused on determining the role of the tumor microenvironment with cancer-cell-intrinsic events and tumor-infiltrating immune cellular properties. However, in the past decade, there has been emerging research aimed at delineating the role of the host microbiome, including the metabolites from microbes and host responses, on pancreatic tumorigenesis. Importantly, there is emerging evidence suggesting the beneficial role of a gut microbiome transplant to improve immunotherapeutic outcomes in cancer patients. In this review, we summarize the recent understanding of the role of the microbiome in pancreatic cancer progression, along with its clinical diagnostic and therapeutic implications.

Low-Salt Diet Reduces Anti-CTLA4 Mediated Systemic Immune-Related Adverse Events while Retaining Therapeutic Efficacy against Breast Cancer.

Immune checkpoint inhibitor (ICI) therapy has revolutionized the breast cancer treatment landscape. However, ICI-induced systemic inflammatory immune-related adverse events (irAE) remain a major clinical challenge. Previous studies in our laboratory and others have demonstrated that a high-salt (HS) diet induces inflammatory activation of CD4+T cells leading to anti-tumor responses. In our current communication, we analyzed the impact of dietary salt modification on therapeutic and systemic outcomes in breast-tumor-bearing mice following anti-cytotoxic T-lymphocyte-associated protein 4 (CTLA4) monoclonal antibody (mAb) based ICI therapy. As HS diet and anti-CTLA4 mAb both exert pro-inflammatory activation of CD4+T cells, we hypothesized that a combination of these would lead to enhanced irAE response, while low-salt (LS) diet through blunting peripheral inflammatory action of CD4+T cells would reduce irAE response. We utilized an orthotopic murine breast tumor model by injecting Py230 murine breast cancer cells into syngeneic C57Bl/6 mice. In an LS diet cohort, anti-CTLA4 mAb treatment significantly reduced tumor progression (day 35, 339 ± 121 mm3), as compared to isotype mAb (639 ± 163 mm3, p < 0.05). In an HS diet cohort, treatment with anti-CTLA4 reduced the survival rate (day 80, 2/15) compared to respective normal/regular salt (NS) diet cohort (8/15, p < 0.05). Further, HS plus anti-CTLA4 mAb caused an increased expression of inflammatory cytokines (IFNγ and IL-1ß) in lung infiltrating and peripheral circulating CD4+T cells. This inflammatory activation of CD4+T cells in the HS plus anti-CTLA4 cohort was associated with the upregulation of inflammasome complex activity. However, an LS diet did not induce any significant irAE response in breast-tumor-bearing mice upon treatment with anti-CTLA4 mAb, thus suggesting the role of high-salt diet in irAE response. Importantly, CD4-specific knock out of osmosensitive transcription factor NFAT5 using CD4cre/creNFAT5flox/flox transgenic mice caused a downregulation of high-salt-mediated inflammatory activation of CD4+T cells and irAE response. Taken together, our data suggest that LS diet inhibits the anti-CTLA4 mAb-induced irAE response while retaining its anti-tumor efficacy.

The Meharry-Vanderbilt-Tennessee State University Cancer Partnership (MVTCP): History and Highlights of 20 Years of Accomplishments.

Cancer health disparities among populations are the result of a combination of socioeconomic, environmental, behavioral, and biological factors, which affect cancer incidence, prevalence, mortality, survivorship, financial burden, and screening rates. The long-standing Meharry Medical College (MMC), Vanderbilt-Ingram Cancer Center (VICC), Tennessee State University (TSU) Cancer Partnership has built an exceptional cancer research and training environment to support the efforts of diverse investigators in addressing disparities. Over the past 20 years, collaborative partnership efforts across multiple disciplines have supported research into the determinants of cancer health disparities at a National Cancer Institute-designated comprehensive cancer center (VICC) along with enhancing research infrastructure and training at MMC and TSU, two institutions that serve predominantly underserved populations and underrepresented students. Moreover, the geographical placement of this partnership in Tennessee, a region with some of the highest cancer incidence and mortality in the United States, has provided an especially important opportunity to positively affect outcomes for cancer patients.

Cancer Salt Nostalgia.

High-salt (sodium chloride) diets have been strongly associated with disease states and poor health outcomes. Traditionally, the impact of salt intake is primarily studied in cardiovascular diseases, hypertension and renal diseases; however, recently there has been increasing evidence demonstrating the role of salt in autoimmune diseases. Salt has been shown to modulate the inflammatory activation of immune cells leading to chronic inflammation-related ailments. To date, there is minimal evidence showing a direct correlation of salt with cancer incidence and/or cancer-related adverse clinical outcomes. In this review article, we will discuss the recent understanding of the molecular role of salt, and elucidate the apparent double-edged sword nature of the relationship between salt and cancer progression.

Ex Vivo High Salt Activated Tumor-Primed CD4+T Lymphocytes Exert a Potent Anti-Cancer Response.

Cell based immunotherapy is rapidly emerging as a promising cancer treatment. A modest increase in salt (sodium chloride) concentration in immune cell cultures is known to induce inflammatory phenotypic differentiation. In our current study, we analyzed the ability of salt treatment to induce ex vivo expansion of tumor-primed CD4 (cluster of differentiation 4)+T cells to an effector phenotype. CD4+T cells were isolated using immunomagnetic beads from draining lymph nodes and spleens from tumor bearing C57Bl/6 mice, 28 days post-injection of Py230 syngeneic breast cancer cells. CD4+T cells from non-tumor bearing mice were isolated from splenocytes of 12-week-old C57Bl/6 mice. These CD4+T cells were expanded ex vivo with five stimulation cycles, and each cycle comprised of treatment with high salt (Δ0.035 M NaCl) or equimolar mannitol controls along with anti-CD3/CD28 monoclonal antibodies for the first 3 days, followed by the addition of interleukin (IL)-2/IL-7 cytokines and heat killed Py230 for 4 days. Ex vivo high salt treatment induced a two-fold higher Th1 (T helper type 1) expansion and four-fold higher Th17 expansion compared to equimolar mannitol treatment. Importantly, the high salt expanded CD4+T cells retained tumor-specificity, as demonstrated by higher in vitro cytotoxicity against Py230 breast cancer cells and reduced in vivo syngeneic tumor growth. Metabolic studies revealed that high salt treatment enhanced the glycolytic reserve and basal mitochondrial oxidation of CD4+T cells, suggesting a role of high salt in enhanced pro-growth anabolic metabolism needed for inflammatory differentiation. Mechanistic studies demonstrated that the high salt induced switch to the effector phenotype was mediated by tonicity-dependent transcription factor, TonEBP/NFAT5. Using a transgenic murine model, we demonstrated that CD4 specific TonEBP/NFAT5 knock out (CD4cre/creNFAT5flox/flox) abrogated the induction of the effector phenotype and anti-tumor efficiency of CD4+T cells following high salt treatment. Taken together, our data suggest that high salt-mediated ex vivo expansion of tumor-primed CD4+T cells could induce effective tumor specific anti-cancer responses, which may have a novel cell-based cancer immunotherapeutic application.

Perplexing Role of P-Glycoprotein in Tumor Microenvironment.

Development of multidrug resistance (MDR) still remains a major obstacle to the long-term success of cancer therapy. P-glycoprotein (P-gp) is a well-identified membrane transporter with capability to efflux drug molecules out of the cancer cell leading to reduced efficiency of chemotherapy. Cancer cells upregulate P-gp expression as an adaptive response to evade chemotherapy mediated cell death. While several P-gp inhibitors have been discovered by in silico and pre-clinical studies, very few have successfully passed all phases of the clinical trials. Studies show that application of P-gp inhibitors in cancer therapy regimen following development of MDR achieved limited beneficial outcomes. While, the non-specific substrate binding to P-gp has made the drug-design a challenge, a bigger perplexing challenge comes from its role in tumor immunology. Expression of P-gp was noted immune cell phenotypes with apparently antagonistic functionality. Both pro-tumor MΦ2-macrophages and, anti-tumor NK-cell and Th17/CD4+T cell subsets have shown enhanced expression of P-gp. While drug based inhibition of P-gp in pro-tumor immune cell phenotypes could promote tumor elimination, however, it would not be a rational choice to exert inhibition of P-gp on anti-tumor immune cell phenotypes. This mutually exclusive paradigm of P-gp functionality requires a more comprehensive and detailed understanding of its role in tumor microenvironment with active interplay of cancer and immune cells in the tumor mileu. In this review, we focus on the current understanding of the role of P-gp in cancer cells and immune cells and finally attempt to highlight some caveats in the current understanding of its role in comprehensive tumor microenvironment along with challenges in the development of P-gp inhibitors toward anti-cancer therapy.

Role of BET Inhibitors in Triple Negative Breast Cancers.

Bromodomain and extraterminal domain (BET) proteins have evolved as key multifunctional super-regulators that control gene expression. These proteins have been shown to upregulate transcriptional machinery leading to over expression of genes involved in cell proliferation and carcinogenesis. Based on favorable preclinical evidence of BET inhibitors in various cancer models; currently, 26 clinical trials are underway in various stages of study on various hematological and solid organ cancers. Unfortunately, preliminary evidence for these clinical studies does not support the application of BET inhibitors as monotherapy in cancer treatment. Furthermore, the combinatorial efficiency of BET inhibitors with other chemo-and immunotherapeutic agents remain elusive. In this review, we will provide a concise summary of the molecular basis and preliminary clinical outcomes of BET inhibitors in cancer therapy, with special focus on triple negative breast cancer.

Methylselenol producing selenocompounds enhance the efficiency of mammaglobin-A peptide vaccination against breast cancer cells.

Previous phase I DNA-vaccine based clinical trials using Mammaglobin-A (Mam-A), a human breast tumor associated antigen (TAA), demonstrated that this agent was safe and efficient at treating patients with stage IV breast cancer. The long-term success of cancer vaccines is limited by the diminished expression of human leukocyte antigen (HLA) class I molecules in the tumor microenvironment. The current study assessed the impact of various selenocompounds on the expression of HLA class I molecules in THP-1 cells, an apparent proficient antigen that presents a human monocyte-like cell line, and their eventual activation of MamA2.1 (HLA-A2 immunodominant epitope of Mam-A) specific cytotoxic CD8+ T lymphocytes (CTLs). The results revealed that, following treatment with methylselenol producing compounds [methylselenic acid (MSA) and dimethylselenide (DMDSe)], the expression of HLA class-I was increased and components involved with the antigen presentation machinery of THP-1 cells were upregulated. Furthermore, CTLs activated by MamA2.1 peptide presenting THP-1 cells, pre-treated with MSA and DMDSe, demonstrated an enhanced cytotoxicity in HLA-A2+/Mam-A+ AU565 and UACC-812 breast cancer cell lines when compared with CTLs activated by THP-1 cells without drug treatment. However, no significant cytotoxicity was observed under similar conditions in HLA-A2+/Mam-A- MCF-7 and MDA-MB-231 breast cancer cell lines. The results indicated that treatment with methylselenol producing compounds retained antigen-dependent activation of CD8+ T cells. The data of the current study demonstrated that MSA and DMDSe potentiated effector cytotoxic responses following TAA specific activation of CTLs, indicating their future role as vaccine adjuvants in cancer immunotherapy.

Immunogenicity of Tumor Initiating Stem Cells: Potential Applications in Novel Anticancer Therapy.

Tumor initiating stem cells (TISCs) are a subset of tumor cells, which are implicated in cancer relapse and resistance to chemotherapy. The metabolic programs that drive TISC functions are exquisitely unique and finely-tuned by various oncogene-driven transcription factors to facilitate pro-cancerous adaptive challenges. While this change in TISC metabolic machinery allows for the identification of associated molecular targets with diagnostic and prognostic value, these molecules also have a potential immunological application. Recent studies have shown that these TISC-associated molecules have strong antigenic properties enabling naïve CD8+T lymphocytes to differentiate into cytotoxic effector phenotype with anticancer potential. In spite of the current challenges, a detailed understanding in this direction offers an immense immunotherapeutic opportunity. In this review, we highlight the molecular targets that characterize TISCs, the metabolic landscape of TISCs, potential antitumor immune cell activation, and the opportunities and challenges they present in the development of new cancer therapeutics.

Oligodeoxynucleotides ODN 2006 and M362 Exert Potent Adjuvant Effect through TLR-9/-6 Synergy to Exaggerate Mammaglobin-A Peptide Specific Cytotoxic CD8+T Lymphocyte Responses against Breast Cancer Cells.

Mammaglobin-A (MamA) is overexpressed in 40-80% of all human breast cancers. Recent phase I clinical trials of the MamA DNA vaccine showed encouraging safety outcomes. However, this vaccine elicited only a modest increase in MamA specific CD8+T lymphocyte (CTL) activation. As vaccine adjuvants play a critical role in enhancing the immunotherapeutic efficiency of vaccines, we tested the potential role of three synthetic CpG oligodeoxynucleotides (ODN2216-class A ODN, ODN2006-class B ODN, and ODN M362-class C ODN) to further enhance MamA specific CTL responses. Towards this, naïve CD8+T cells were obtained from healthy HLA-A2+ human donors. The HLA-A2 specific immunodominant epitope of MamA, MamA2.1 (LIYDSSLCDL), was utilized to activate naïve CD8+T cells. The THP-1 (HLA-A2+) cells were used as antigen presenting cells to stimulate naïve CD8+T cells along with (or without) co-treatment of various ODNs mentioned above. Activation of naïve CD8+T cells with the MamA2.1 peptide along with ODNs demonstrated enhanced MamA specific CTL mediated cytotoxicity on AU565 (HLA-A+/MamA+) breast cancer cells following co-treatment with ODN2006 and M362 compared to ODN2216 or MamA2.1 peptide alone. However, no significant cytotoxicity was noted upon treatment of MamA2.1 activated CTLs on MCF7 (HLA-A+/MamA-) cells, suggesting that the activation of CTLs is specific to the MamA antigen. Functional characterization studies demonstrated specific IL-12 mediated cross-talk between TLR-6 and -9 in THP-1 cells following stimulation with ODN2006 and M362, which was critical for the final cytotoxic activation of CD8+T lymphocytes. Based on these data, we conclude that ODN2006 and ODN M362 exerted a strong adjuvant effect through induction of the initial innate immune response through TLR9 upregulation followed by enhanced MamA specific CTL dependent adaptive immune responses. Our current data provide evidence for the application of Class-B/-C-CpG-ODNs as potential vaccine adjuvants towards enhancing the success of MamA based breast cancer vaccination.

Impact of Precision Medicine on Drug Repositioning and Pricing: A Too Small to Thrive Crisis.

The pricing of targeted medicines continues to be a major area of contention in healthcare economics. This issue is further complicated by redefining the role of molecular testing in precision medicine. Currently, whilst pricing of clinical laboratory diagnostics is cost-based, drug pricing is value-based. The pricing for molecular testing is under pressure to change the traditional business model, for it has a critical subsidiary role in determining the final value of targeted medicines. The market size for drugs is reduced by molecular testing when patients with the same disease are stratified based on their genetics, it is critical to determine the value of this new enhanced drug specificity to realize its full pricing potential. However, these value-based pricing strategies require a careful understanding of changing market conditions, especially, in the context of stratified patient segments made possible by precision medicine. In this article, we discuss the various factors impacting pricing decisions, and consider evolving economic trends in precision medicine.

High salt induces P-glycoprotein mediated treatment resistance in breast cancer cells through store operated calcium influx.

Recent evidence from our laboratory has demonstrated that high salt (Δ0.05 M NaCl) induced inflammatory response and cancer cell proliferation through salt inducible kinase-3 (SIK3) upregulation. As calcium influx is known to effect inflammatory response and drug resistance, we examined the impact of high salt on calcium influx in breast cancer cells. Treatment of MCF-7 and MDA-MB-231 cells with high salt induced an enhanced intracellular calcium intensity, which was significantly decreased by store operated calcium entry (SOCE) inhibitor co-treatment. Further, high salt induced P-glycoprotein (P-gp) mediated paclitaxel drug resistance in breast cancer cells. Murine tumor studies demonstrated that injection of MCF-7 cells cultured in high salt, exerted higher tumorigenicity compared to the basal cultured counterpart. Knock down of SIK3 by specific shRNA inhibited tumorigenicty, expression of SOCE regulators and P-gp activity, suggesting SIK3 is an upstream mediator of SOCE induced calcium influx. Furthermore, small molecule inhibitor, prostratin, exerted anti-tumor effect in murine models through SIK3 inhibition. Taken together, we conclude that SIK3 is an upstream regulator of store operated calcium entry proteins, Orai1 and STIM1, and mediates high salt induced inflammatory cytokine responses and P-gp mediated drug resistance. Therefore, small molecule inhibitors, such as prostratin, could offer novel anti-cancer approaches.

Potential anticancer effect of prostratin through SIK3 inhibition.

Prostratin, a phorbol ester natural plant compound, has been demonstrated to exert an anti-retroviral effect through activation of latent cluster of differentiation (CD)4+T lymphocytes and inhibition of viral entry into the cell through downregulation of chemokine receptor type 4 (CXCR4) expression. However, the potential effect of prostratin on cancer is yet to be defined. As CXCR4 is well known to induce cancer migration, it was hypothesized that prostratin induces an anti-cancer effect through inhibition of CXCR4 expression. The authors previously demonstrated that high stimulating conditions (sub-minimal IL-17, 0.1 ng/ml, synergized with high salt, Δ0.05 M NaCl) promote breast cancer cell proliferation and CXCR4 expression through upregulation of salt-inducible kinase (SIK)-3. The present study demonstrated that prostratin selectively exerted increased cytotoxicity (IC50 of 7 µM) when breast cancer cells were cultured in high stimulating conditions, compared with regular basal culture conditions (IC50 of 35 µM). Furthermore, the cytotoxic potential of prostratin was increased seven-fold in the four breast cancer cell lines (MCF-7, MDA-MB-231, BT-20 and AU-565) compared with the non-malignant MCF10A breast epithelial cell line. This suggested that prostratin specifically targets cancer cells over normal cells. Mechanistic studies revealed that prostratin inhibited CXCR4 expression in breast cancer cells through downregulation of SIK3 expression. Overall, the data suggest that prostratin is a novel drug target for the pro-oncogenic factor SIK3. These studies could form a basis for further research to evaluate the anticancer effect of prostratin in a combinatorial chemotherapeutic regimen.

Critical role of SIK3 in mediating high salt and IL-17 synergy leading to breast cancer cell proliferation.

Chronic inflammation is a well-known precursor for cancer development and proliferation. We have recently demonstrated that high salt (NaCl) synergizes with sub-effective interleukin (IL)-17 to induce breast cancer cell proliferation. However, the exact molecular mechanisms mediating this effect are unclear. In our current study, we adopted a phosphoproteomic-based approach to identify salt modulated kinase-proteome specific molecular targets. The phosphoprotemics based binary comparison between heavy labelled MCF-7 cells treated with high salt (Δ0.05 M NaCl) and light labelled MCF-7 cells cultured under basal conditions demonstrated an enhanced phosphorylation of Serine-493 of SIK3 protein. The mRNA transcript and protein expression analysis of SIK3 in MCF-7 cells demonstrated a synergistic enhancement following co-treatment with high salt and sub-effective IL-17 (0.1 ng/mL), as compared to either treatments alone. A similar increase in SIK3 expression was observed in other breast cancer cell lines, MDA-MB-231, BT20, and AU565, while non-malignant breast epithelial cell line, MCF10A, did not induce SIK3 expression under similar conditions. Biochemical studies revealed mTORC2 acted as upstream mediator of SIK3 phosphorylation. Importantly, cell cycle analysis by flow cytometry demonstrated SIK3 induced G0/G1-phase release mediated cell proliferation, while SIK3 silencing abolished this effect. Also, SIK3 induced pro-inflammatory arginine metabolism, as evidenced by upregulation of the enzymes iNOS and ASS-1, along with downregulation of anti-inflammatory enzymes, arginase-1 and ornithine decarboxylase. Furthermore, gelatin zymography analysis has demonstrated that SIK3 induced expression of tumor metastatic CXCR4 through MMP-9 activation. Taken together, our data suggests a critical role of SIK3 in mediating three important hallmarks of cancer namely, cell proliferation, inflammation and metastasis. These studies provide a mechanistic basis for the future utilization of SIK3 as a key drug discovery target to improve breast cancer therapy.

The Five Immune Forces Impacting DNA-Based Cancer Immunotherapeutic Strategy.

DNA-based vaccine strategy is increasingly realized as a viable cancer treatment approach. Strategies to enhance immunogenicity utilizing tumor associated antigens have been investigated in several pre-clinical and clinical studies. The promising outcomes of these studies have suggested that DNA-based vaccines induce potent T-cell effector responses and at the same time cause only minimal side-effects to cancer patients. However, the immune evasive tumor microenvironment is still an important hindrance to a long-term vaccine success. Several options are currently under various stages of study to overcome immune inhibitory effect in tumor microenvironment. Some of these approaches include, but are not limited to, identification of neoantigens, mutanome studies, designing fusion plasmids, vaccine adjuvant modifications, and co-treatment with immune-checkpoint inhibitors. In this review, we follow a Porter's analysis analogy, otherwise commonly used in business models, to analyze various immune-forces that determine the potential success and sustainable positive outcomes following DNA vaccination using non-viral tumor associated antigens in treatment against cancer.

Inflammatory role of high salt level in tumor microenvironment (Review).

Chronic inflammation is known to play a critical role in cancer development and progression. High salt is known to mediate several chronic inflammatory diseases including hypertension, myocardial infarction, neurological ischemic attack, autoimmune diseases and cancers. High salt level is shown to induce angiogenesis and immune-dysfunction, both of which play a direct role in cancer proliferation. Furthermore, salt has been suggested to enhance Warburg-like metabolic phenotype in cancer cells and at the same time also induce pro-tumor MΦ2-macrophage phenotype. Recent studies have identified several molecular targets such as tonicity specific transcript factor NFAT5/TonEBP, sodium ion channel γENaC, and vascular endothelial growth factor, VEGF, which are upregulated under high salt external environment. These molecular targets offer futuristic therapeutic application in precision medicine. In this review, we discuss the current understanding of the salt mediated metabolic and immune dysfunctions playing a potential role in cancerous changes.

NFAT5/STAT3 interaction mediates synergism of high salt with IL-17 towards induction of VEGF-A expression in breast cancer cells.

Chronic inflammation has been considered an important player in cancer proliferation and progression. High salt (sodium chloride) levels have been considered a potent inducer of chronic inflammation. In the present study, the synergistic role of high salt with interleukin (IL)-17 towards induction of the inflammatory and angiogenic stress factor vascular endothelial growth factor (VEGF)-A was investigated. Stimulation of MCF-7 breast cancer cells with high salt (0.2 M NaCl) and sub-minimal IL-17 (1 ng/ml) enhanced the expression of VEGF-A (2.9 and 2.6-fold, respectively, P<0.05) compared with untreated cells. Furthermore, co-treatment with both high salt and sub-minimal IL-17 led to a 5.9-fold increase in VEGF-A expression (P<0.01), thus suggesting a synergistic role of these factors. VEGF-A promoter analysis and specific small interfering RNA knock-down of transcription factors revealed that high salt induced VEGF-A expression through nuclear factor of activated T-cells (NFAT)5, while IL-17 induced VEGF-A expression via signal transducer and activator of transcription (STAT)3 signaling mechanisms. Treatment of normal human aortic endothelial cells with the supernatant of activated MCF-7 cells enhanced cell migration and induced expression of migration-specific factors, including vascular cell adhesion protein, ß1 integrin and cluster of differentiation 31. These data suggest that high salt levels synergize with pro-inflammatory IL-17 to potentially induce cancer progression and metastasis through VEGF-A expression. Therefore, low-salt diet, anti-NFAT5 and anti-STAT3 therapies may provide novel avenues for enhanced efficiency of the current cancer therapy.