Lymphangiogenesis and Axillary Lymph Node Metastases Correlated with VEGF-C Expression in Two Immunocompetent Mouse Mammary Carcinoma Models

Hormone Receptor-Dependent Correlations Between Angiopoietins and VEGF-C in Primary Breast Cancer: Insights Into Lymphangiogenic Biomarkers

BACKGROUND

Biomarkers of angiogenesis and lymphangiogenesis have been explored in cancer prognostic models; however, their potential role in assessing local tumor invasiveness remains poorly understood.

AIMS

This study aimed to evaluate the correlations of angiogenic biomarkers, specifically the angiopoietin (ANG)-Tie system and vascular endothelial growth factor-C (VEGF-C), with lymphangiogenesis and the related histopathological characteristics in Iranian women with breast cancer.

METHODS AND RESULTS

In this consecutive case series (n = 149) from the Breast Cancer Risk and Lifestyle (BCRL) study, plasma levels of pro-angiogenic factors, including VEGF-C, ANGs, and Tie-2, were assessed using ELISA. Clinicopathological data were collected, excluding stage IV cases to focus on patients with localized disease. Axillary lymph node metastasis (ANLM), and vascular invasion (VI) were common in the study population, occurring in 61.5% and 77.6% of cases, respectively (p < 0.01). Estrogen receptor-positive (ER+) tumors were observed in 89.1% of ANLM+ participants, while human epidermal growth factor receptor-2-positive (HER-2+) tumors were identified in 22.8% of patients with ALNM. Plasma levels of ANG-1 (r = 0.19) and VEGF-C (r = 0.29) were positively correlated with the ALNM ratio (p < 0.05). Multivariate analysis in patients with grade II tumors revealed significant inverse correlations between VEGF-C and angiogenic biomarkers, including ANG-2 (β = -0.25), the ANG-2/Tie-2 ratio (β = -0.28), and the (ANG-1 + ANG-2)/Tie-2 ratio (β = -0.29) (p < 0.05). Receiver operating characteristic (ROC) curve analysis indicated that ANG-2 could effectively assess ALNM status, with an optimal cutoff of 3.39 pg/mL, identifying ALNM in 66.0% of patients with low VEGF-C levels (95% CI: 0.54-0.78), increasing to 68.0% when combined with ANG-1 as the ANGs/Tie-2 ratio (95% CI: 0.56-0.80). In ER+ tumors, high plasma ANG-2 levels were observed (p < 0.05). Significantly higher levels of the (ANG-1 + ANG-2)/VEGF-C ratio were noted in patients with VI+ (p < 0.05). Findings descriptively highlighted ER+ status as a common characteristic in VI+ and ALNM+ tumors. In HER-2+ patients, both ANG-1 and the (ANG-1 + ANG-2)/Tie-2 ratio showed inverse correlations with VEGF-C, while in ER- breast cancer patients, ANG-2 was inversely correlated with VEGF-C.

CONCLUSION

These findings provide new insights into the inverse correlation between plasma levels of ANGs and VEGF-C, particularly in cases with positive ALNM, underscoring the role of hormone receptor-dependent characteristics. The integration of the triple angiogenic biomarkers ANG-2/Tie-2/VEGF-C within the tumor microenvironment, combined with the regulatory influence of hormonal receptors, merits further investigation as a potential biomarker panel for identifying lymphatic anomalies and VI positivity in breast cancer patients.

Role of CD44-Positive Extracellular Vesicles Derived from Highly Metastatic Mouse Mammary Carcinoma Cells in Pre-Metastatic Niche Formation

Malignant breast cancers pose a notable challenge when it comes to treatment options. Recently, research has implicated extracellular vesicles (EVs) secreted by cancer cells in the formation of a pre-metastatic niche. Small clumps of CD44-positive breast cancer cells are efficiently transferred through CD44-CD44 protein homophilic interaction. This study aims to examine the function of CD44-positive EVs in pre-metastatic niche formation in vitro and to suggest a more efficacious EV formulation. We used mouse mammary carcinoma cells, BJMC3879 Luc2 (Luc2 cells) as the source of CD44-positive EVs and mouse endothelial cells (UV2 cells) as the recipient cells in the niche. Luc2 cells exhibited an enhanced secretion of EVs expressing CD44 and endothelial growth factors (VEGF-A, -C) under 20% O2 (representative of the early stage of tumorigenesis) compared to its expression under 1% O2 (in solid tumor), indicating that pre-metastatic niche formation occurs in the early stage. Furthermore, UV2 endothelial cells expressing CD44 demonstrated a high level of engulfment of EVs that had been supplemented with hyaluronan, and the proliferation of UV2 cells occurred following the engulfment of EVs. These results suggest that anti-VEGF-A and -C encapsulated, CD44-expressing, and hyaluronan-coated EVs are more effective for tumor metastasis.

Charge Reversal Polypyrrole Nanocomplex-Mediated Gene Delivery and Photothermal Therapy for Effectively Treating Papillary Thyroid Cancer and Inhibiting Lymphatic Metastasis

As a traditional treatment for papillary thyroid cancer (PTC), surgical resection of diseased tissues often brings lots of inconveniences to patients, and the tumor recurrence and metastasis are difficult to avoid. Herein, we developed a gene and photothermal combined therapy nanosystem based on a polypyrrole (Ppy)-poly(ethylene imine)-siILK nanocomplex (PPR_ILK) to achieve minimally invasive ablation and lymphatic metastasis inhibition in PTC simultaneously. In this system, gelatin-stabilized Ppy mainly acted as a photothermal- and photoacoustic (PA)-responsive nanomaterial and contributed to its well-behaved photosensitivity in the near-infrared region. Moreover, gelatin-stabilized Ppy possessed a charge reversal function, facilitating the tight conjunction of siILK gene at physiological pH (7.35-7.45) and its automatic release into acidic lysosomes (pH 4.0-5.5); the proton sponge effect generated during this process further facilitated the escape of siILK from lysosomes to the cytoplasm and played its role in inhibiting PTC proliferation and lymphatic metastasis. With the guidance of fluorescence and PA bimodal imaging, gene delivery and Ppy location in tumor regions could be clearly observed. As a result, tumors were completely eradicated by photothermal therapy, and the recurrences and metastases were obviously restrained by siILK.

Metastasis of Breast Cancer Promoted by Circadian Rhythm Disruption due to Light/Dark Shift and its Prevention by Dietary Quercetin in Mice

Epidemiological studies have indicated that a disturbed circadian rhythm resulting from night-shift work is a potential risk factor for breast cancer. However, the mechanism of increased risk of breast cancer by night-shift work remains unclear, and there have been few in vivo studies conducted to definitively associate the two factors. In this study, BJMC3879Luc2 mouse breast cancer cells were transplanted into BALB/c mice. Mice were maintained under lighting conditions that modeled the two-shift system and were investigated for the effect of light/dark cycle disruption on tumor growth and lymph node metastasis. Circadian dysfunction, which was confirmed by measuring circadian locomotor activities using a nano tag device in our light/dark shift model, did not affect tumor growth. However, a significant increase in the number of lymph nodes with distant metastasis was observed. Neutrophil-to-lymphocyte ratio, which is an adverse prognostic factor of breast cancer and also indicator of inflammation, also increased. It has been demonstrated that a chronic inflammatory response is associated with cancer malignancy and poor prognosis in various cancers. These results suggest that night-shift work may also affect distant metastasis and prognosis. In addition, we investigated whether dietary quercetin has anti-metastatic activity against light/dark shift-induced metastasis. A diet containing 0.3 % quercetin significantly inhibited distant lymph node metastasis, particularly metastasis to the iliac and kidney lymph nodes. Our results contribute to our understandings of the effects of the external light environment on breast cancer metastasis and provide a glimpse into potential protective effects of dietary quercetin on light/dark disturbance-induced metastasis.

Indomethacin can induce cell death in rat gastric parietal cells through alteration of some apoptosis- and autophagy-associated molecules

In clinical medicine, indomethacin (IND, a non-steroidal anti-inflammatory drug) is used variously in the treatment of severe osteoarthritis, rheumatoid arthritis, gouty arthritis or ankylosing spondylitis. A common complication found alongside the therapeutic characteristics is gastric mucosal damage. This complication is mediated through apoptosis and autophagy of the gastrointestinal mucosal epithelium. Apoptosis and autophagy are critical homeostatic pathways catalysed by caspases downstream of the gastrointestinal mucosal epithelial injury. Both act through molecular signalling pathways characterized by the initiation, mediation, execution and regulation of the cell regulatory cycle. In this study we hypothesized that dysregulated apoptosis and autophagy are associated with IND-induced gastric damage. We examined the spectra of in vivo experimental gastric ulcers in male Sprague-Dawley rats through gastric gavage of IND. Following an 18-hour fast, IND was administered to experimental rats. They were sacrificed at 3-, 6- and 12-hour intervals. Parietal cells (H⁺ , K⁺ -ATPase β-subunit assay) and apoptosis (TUNEL assay) were determined. The expression of apoptosis-signalling caspase (caspases 3, 8, 9 and 12), DNA damage (anti-phospho-histone H2A.X) and autophagy (MAP-LC3, LAMP-1 and cathepsin B)-related molecules in gastric mucosal cells was examined. The administration of IND was associated with gastric mucosal erosions and ulcerations mainly involving the gastric parietal cells (PCs) of the isthmic and upper neck regions and a time-dependent gradual increase in the number of apoptotic PCs with the induction of both apoptotic (upregulation of caspases 3 and 8) cell death and autophagic (MAP-LC3-II, LAMP-1 and cathepsin B) cell death. Autophagy induced by fasting and IND 3 hours initially prompted the degradation of caspase 8. After 6 and 12 hours, damping down of autophagic activity occurred, resulting in the upregulation of active caspase 8 and its nuclear translocation. In conclusion we report that IND can induce time-dependent apoptotic and autophagic cell death of PCs. Our study provides the first indication of the interactions between these two homeostatic pathways in this context.

Serum vascular endothelial growth factor-C levels predict lymph node metastasis and prognosis of patients with gallbladder cancer

Lymph node metastasis is the primary site of metastasis for patients with gallbladder cancer (GBC). Vascular endothelial growth factor-C (VEGF-C) has been implicated in the control of lymphangiogenesis and lymph node metastasis in various malignant tumors. However, the function of circulating VEGF-C is unclear and it is often difficult to evaluate lymph node metastasis and provide a prognosis for GBC. In the present study, ELISA was used to measure the preoperative serum VEGF-C (sVEGF-C) levels of 51 patients with GBC, 15 patients with chronic cholecystitis and 10 healthy volunteers. The results revealed a significantly increased sVEGF-C level in patients with GBC compared with the healthy donors, however no statistically significant difference was identified between patients with GBC and chronic cholecystitis. sVEGF-C levels were associated with lymph node metastasis in GBC and presented a positive correlation with VEGF-C expression and lymphatic vessel density (LVD) in patients with GBC. The mean survival time with high sVEGF-C was significantly reduced compared with low sVEGF-C. A similar result was also observed for VEGF-C expression and LVD. In summary, sVEGF-C levels may predict lymph node metastasis and the prognosis of patients with GBC.

Indomethacin suppresses LAMP-2 expression and induces lipophagy and lipoapoptosis in rat enterocytes via the ER stress pathway

BACKGROUND

Indomethacin enhances small intestinal epithelial cell apoptosis, which may account for mucosal ulceration. However, the involvement of autophagy in indomethacin-induced enterocyte damage is unreported.

METHODS

Using light microscopy and electron microscopy techniques, Western blot analysis, and pharmacological inhibition of autophagy, we investigated the autophagic response of cultured rat enterocytes to indomethacin treatment (200 µM) at various time points. Furthermore, autophagy was examined in enterocytes of rats given indomethacin by gavage (10 mg/kg).

RESULTS

Our data indicate that indomethacin induced accumulation of cytoplasmic lipid droplets (LDs) in cultured enterocytes, which was associated with time-dependent autophagic responses. Initially (0-6 h), mediated by endoplasmic reticulum stress and suppression of mammalian target of rapamycin, a predominant cytoprotective lipophagy was activated in indomethacin-treated enterocytes, as evidenced by induction and colocalization of LC3-II with LDs, excessive formation of autophagosomes sequestering LDs (autolipophagosomes; ALPs), and decreased viability of enterocytes on blocking autophagy with 3-methyladenine. On prolonged exposure to indomethacin (6-24 h), there was a decrease of LAMP-2 expression in enterocytes coupled with accumulation of ALPs and LDs with fewer autolysosomes in addition to an elevation of lipoapoptosis. These time-dependent autophagic and apoptotic responses to indomethacin treatment were detected in enterocytes of indomethacin-treated rats, confirming in vitro results.

CONCLUSIONS

The findings of this study describe a novel mechanism of enterocyte damage by indomethacin mediated by endoplasmic reticulum stress, accumulation of LDs, and subsequent activation of the early phase of cytoprotective lipophagy. This is followed by a late phase characterized by reduced expression of lysosomal autophagic proteins, accumulation of ALPs, and enhanced lipoapoptosis.

Role of tumor associated macrophages in tumor angiogenesis and lymphangiogenesis

Tumor angiogenesis is an essential process for supplying rapidly growing malignant tissues with essential nutrients and oxygen. An angiogenic switch allows tumor cells to survive and grow, and provides them access to vasculature resulting in metastatic disease. Monocyte-derived macrophages recruited and reprogrammed by tumor cells serve as a major source of angiogenic factors boosting the angiogenic switch. Tumor endothelium releases angiopoietin-2 and further facilitates recruitment of TIE2 receptor expressing monocytes (TEM) into tumor sites. Tumor-associated macrophages (TAM) sense hypoxia in avascular areas of tumors, and react by production of angiogenic factors such as VEGFA. VEGFA stimulates chemotaxis of endothelial cells (EC) and macrophages. In some tumors, TAM appeared to be a major source of MMP9. Elevated expression of MMP9 by TAM mediates extracellular matrix (ECM) degradation and the release of bioactive VEGFA. Other angiogenic factors released by TAM include basic fibroblast growth factor (bFGF), thymidine phosphorylase (TP), urokinase-type plasminogen activator (uPA), and adrenomedullin (ADM). The same factors used by macrophages for the induction of angiogenesis [like vascular endothelial growth factor A (VEGF-A) and MMP9] support lymphangiogenesis. TAM can express LYVE-1, one of the established markers of lymphatic endothelium. TAM support tumor lymphangiogenesis not only by secretion of pro-lymphangiogenic factors but also by trans-differentiation into lymphatic EC. New pro-angiogenic factor YKL-40 belongs to a family of mammalian chitinase-like proteins (CLP) that act as cytokines or growth factors. Human CLP family comprises YKL-40, YKL-39, and SI-CLP. Production of all three CLP in macrophages is antagonistically regulated by cytokines. It was recently established that YKL-40 induces angiogenesis in vitro and in animal tumor models. YKL-40-neutralizing monoclonal antibody blocks tumor angiogenesis and progression. The role of YKL-39 and SI-CLP in tumor angiogenesis and lymphangiogenesis remains to be investigated.