Inhibition of PKA/CREB1 pathway confers sensitivity to ferroptosis in non-small cell lung cancer.

Ferroptosis is a type of regulated cell death characterized by iron accumulation and lipid peroxidation. The molecular mechanisms underlying ferroptosis regulation in non-small cell lung cancer (NSCLC) are poorly understood. In this study, we found that protein kinase A (PKA) inhibition enhanced ferroptosis susceptibility in NSCLC cells, as evidenced by reduced cell viability and increased lipid peroxidation. We further identified cAMP-responsive element protein 1 (CREB1), a transcription factor and a substrate of PKA, as a key regulator of ferroptosis. Knockdown of CREB1 sensitized NSCLC cells to ferroptosis inducers (FINs) and abolished the effects of PKA inhibitor and agonist, revealing the pivotal role of CREB1 in ferroptosis regulation. Using a high-throughput screening approach and subsequent validation by chromatin immunoprecipitation (ChIP) and dual-luciferase assays, we discovered that CREB1 transcriptionally activated stearoyl-CoA desaturase (SCD), an enzyme that catalyzes the conversion of saturated fatty acids to monounsaturated fatty acids. SCD conferred ferroptosis resistance by decreasing the availability of polyunsaturated fatty acids for lipid peroxidation, and its overexpression rescued the effect of CREB1 knockdown on ferroptosis in vitro. Besides, CREB1 knockdown suppressed xenograft tumor growth in the presence of Imidazole Ketone Erastin (IKE), a potent FIN, and this effect was reversed by SCD. Finally, we showed that high expression of CREB1 was associated with poor prognosis in NSCLC patients from public datasets and our institution. Collectively, this study illustrates the effect of PKA/CREB1/SCD axis in regulating ferroptosis of NSCLC, targeting this pathway may provide new strategies for treating NSCLC patients.

Faster SCDNet: Real-Time Semantic Segmentation Network with Split Connection and Flexible Dilated Convolution.

Recently, semantic segmentation has been widely applied in various realistic scenarios. Many semantic segmentation backbone networks use various forms of dense connection to improve the efficiency of gradient propagation in the network. They achieve excellent segmentation accuracy but lack inference speed. Therefore, we propose a backbone network SCDNet with a dual path structure and higher speed and accuracy. Firstly, we propose a split connection structure, which is a streamlined lightweight backbone with a parallel structure to increase inference speed. Secondly, we introduce a flexible dilated convolution using different dilation rates so that the network can have richer receptive fields to perceive objects. Then, we propose a three-level hierarchical module to effectively balance the feature maps with multiple resolutions. Finally, a refined flexible and lightweight decoder is utilized. Our work achieves a trade-off of accuracy and speed on the Cityscapes and Camvid datasets. Specifically, we obtain a 36% improvement in FPS and a 0.7% improvement in mIoU on the Cityscapes test set.

NAP1L1 interacts with hepatoma-derived growth factor to recruit c-Jun inducing breast cancer growth.

BACKGROUND: Breast cancer is a common cancer among women in the world. However, its pathogenesis is still to be determined. The role and molecular mechanism of Nucleosome Assembly Protein 1 Like 1 (NAP1L1) in breast cancer have not been reported. Elucidation of molecular mechanism might provide a novel therapeutic target for breast cancer treatment. METHODS: A bioinformatics analysis was conducted to determine the differential expression of NAP1L1 in breast cancer and find the potential biomarker that interacts with NAP1L1 and hepatoma-derived growth factor (HDGF). The expression of NAP1L1 in tissues was detected by using immunohistochemistry. Breast cancer cells were transfected with the corresponding lentiviral particles and siRNA. The efficiency of transfection was measured by RT-qPCR and western blotting. Then, MTT, Edu, plate clone formation, and subcutaneous tumorigenesis in nude mice were used to detect the cell proliferation in breast cancer. Furthermore, coimmunoprecipitation (Co-IP) assay and confocal microscopy were performed to explore the detailed molecular mechanism of NAP1L1 in breast cancer. RESULTS: In this study, NAP1L1 protein was upregulated based on the Clinical Proteomic Tumor Analysis Consortium (CPTAC) database. Consistent with the prediction, immunohistochemistry staining showed that NAP1L1 protein expression was significantly increased in breast cancer tissues. Its elevated expression was an unfavorable factor for breast cancer clinical progression and poor prognosis. Stably or transiently knocking down NAP1L1 reduced the cell growth in vivo and in vitro via repressing the cell cycle signal in breast cancer. Furthermore, the molecular basis of NAP1L1-induced cell cycle signal was further studied. NAP1L1 interacted with the HDGF, an oncogenic factor for tumors, and the latter subsequently recruited the key oncogenic transcription factor c-Jun, which finally induced the expression of cell cycle promoter Cyclin D1(CCND1) and thus the cell growth of breast cancer. CONCLUSIONS: Our data demonstrated that NAP1L1 functions as a potential oncogene via interacting with HDGF to recruit c-Jun in breast cancer.

Additional adjuvant capecitabine in early breast cancer patients: a meta-analysis of randomized controlled trials.

Aims: To assess the efficacy and safety of adjuvant capecitabine in early breast cancer patients. Methods: A literature search of databases was conducted to identify randomized controlled trials reporting the efficacy and toxicity of capecitabine as adjuvant therapy in early breast cancer patients. Results: Six studies were eligible and included a total of 6941 patients. Disease-free survival (hazard ratio = 0.79; 95% CI = 0.71-0.88; p < 0.0001) was significantly improved with additional capecitabine, whereas improvement in overall survival (OS) was not significant. The more pronounced benefits in both disease-free survival and OS were observed among triple-negative breast cancer patients. Conclusion: Additional capecitabine in the adjuvant setting conferred substantial disease-free survival benefit and a tendency toward improved OS. Triple-negative breast cancer patients can benefit from capecitabine irrespective of the administration sequence. Capecitabine may be considered a preferred additional treatment for early-stage triple-negative breast cancer patients, and sequential capecitabine can serve as an alternative choice for patients with poor tolerance.

Lay abstract The authors' meta-analysis focused on the adjuvant role of capecitabine in early-stage breast cancer patients. The authors combined data from different studies to show that disease-free survival was significantly improved with additional capecitabine as adjuvant chemotherapy. The more pronounced survival benefits were observed among triple-negative breast cancer patients irrespective of the administration sequence (concurrent/sequential). Capecitabine may be considered a preferred additional treatment for early-stage triple-negative breast cancer patients, and sequential capecitabine can serve as an alternative choice for patients with poor tolerance.

Graphene-based nanomaterials for breast cancer treatment: promising therapeutic strategies.

Breast cancer is the most common malignancy in women, and its incidence increases annually. Traditional therapies have several side effects, leading to the urgent need to explore new smart drug-delivery systems and find new therapeutic strategies. Graphene-based nanomaterials (GBNs) are potential drug carriers due to their target selectivity, easy functionalization, chemosensitization and high drug-loading capacity. Previous studies have revealed that GBNs play an important role in fighting breast cancer. Here, we have summarized the superior properties of GBNs and modifications to shape GBNs for improved function. Then, we focus on the applications of GBNs in breast cancer treatment, including drug delivery, gene therapy, phototherapy, and magnetothermal therapy (MTT), and as a platform to combine multiple therapies. Their advantages in enhancing therapeutic effects, reducing the toxicity of chemotherapeutic drugs, overcoming multidrug resistance (MDR) and inhibiting tumor metastasis are highlighted. This review aims to help evaluate GBNs as therapeutic strategies and provide additional novel ideas for their application in breast cancer therapy.

Synergistic Chemotherapy for Breast Cancer and Breast Cancer Brain Metastases via Paclitaxel-Loaded Oleanolic Acid Nanoparticles.

Breast cancer is the most common type of cancer in women. About 12% of all women in the United States will be diagnosed with breast cancer over their lifetimes. At the same time, incidences of brain metastases (BMs) are increasing and represent an emerging health threat. However, there is no effective chemotherapy for breast cancer brain metastases (BCBMs), which is largely due to lack of efficient delivery of antitumor drugs or drug combinations to the brain. In this study, oleanolic acid (OA), a natural pentacyclic triterpenoid compound with excellent antitumor activity, was found to form nanoparticles (NPs) and efficiently penetrate the brain for BCBMs treatment. On the basis of these findings, we developed a synergistic combinatorial chemotherapeutic regimen by formulating paclitaxel (PTX) into OA NPs and demonstrated that the resulting PTX-OA NPs effectively inhibited primary breast cancer and BCBMs in mouse xenografts. Collectively, this study introduces a new direction to treat primary breast cancer and BCBMs through noninvasive combination chemotherapy.

Oxygen self-enriched nanoplatform combined with US imaging and chemo/photothermal therapy for breast cancer.

Oxygen-saturated perfluorohexane-cored, cisplatin (Pt)-decorated hollow gold nanospheres (Pt-HAuNS-PFH@O2) have been synthesized for ultrasound (US) imaging-guided tumor treatment depending on chemo/photothermal therapy, relief of hypoxia, and photothermal induced US contrast signal. Both NIR laser-induced hyperthermia generation by gold nanospheres and acidity triggered release of Pt resulted in high toxicity after internalization by breast cancer cells. According to ex vivo immunofluorescence investigation and in vivo pharmacodynamic studies on MDA-MB-231 tumor bearing mice, the susceptibility of tumors to Pt-HAuNS-PFH@O2 was improved by the relief of hypoxia. In addition, US imaging under different conditions verified the amplified US contrast property of Pt-HAuNS-PFH@O2 by the heat-dependent liquid-gas conversion of PFH. Overall, Pt-HAuNS-PFH@O2 can be promisingly used as an oxygen self-enriched nanoplatform for US imaging-guided chemo/photothermal therapy.

Gemcitabine and Capecitabine Combination Chemotherapy in Patients with Metastatic Breast Cancer Pretreated with Anthracyclines and/or Taxanes.

BACKGROUND: Owing to the need for effective and tolerable new regimens for the treatment of patients with metastatic breast cancer (MBC) previously treated with anthracyclines and/or taxanes, we aimed to assess the activity and safety of the gemcitabine plus capecitabine combination chemotherapy. METHODS: Sixty-four patients were enrolled. Treatment consisted of gemcitabine 1,000 mg/m2 intravenously on days 1 and 8, plus oral capecitabine at 1,250 mg/m2 twice daily on days 1-14. The primary end point was the overall response rate (ORR). Secondary objectives included the disease control rate (DCR), overall survival (OS), progression-free survival (PFS), toxicity, and predictive factors. RESULTS: In the 64 patients, the ORR and DCR was 28.1 and 67.2%. Median OS and PFS were 23.6 and 13.4 months, respectively. Toxicities were mild and curable. CONCLUSION: The combination of gemcitabine and capecitabine is an effective and tolerable treatment for MBC previously treated with anthracyclines and/or taxanes.

Invasive micropapillary carcinoma of the breast had poor clinical characteristics but showed no difference in prognosis compared with invasive ductal carcinoma.

BACKGROUND: It is controversial for prognosis of invasive micropapillary carcinoma (IMPC) compared with invasive ductal carcinoma (IDC) of the breast. To better understand the difference between IMPC and IDC prognoses, we conducted this retrospective study. METHODS: Data from 33 patients with IMPC were retrospectively reviewed, and the clinicopathologic characteristics and survival status were compared with those of 347 patients with IDC who were treated during the same period. RESULTS: The IMPC cases were of larger tumor size, greater proportion of nodal involvement, and an increased incidence of lymphovascular invasion compared with IDC cases. The overall survival (OS), local relapse-free survival (LRFS), distant metastasis-free survival (DMFS), and failure-free survival (FFS) rates were not significantly different between IMPC and IDC. The 3-year OS rate was 97 vs 94.2 % for the IMPC and IDC patients, respectively. The 3-year FFS rate was 87.9 vs 86.2 % for the IMPC and IDC patients, respectively. For IMPC patients, the 3-year LRFS rate was 93.9 % and in IDC patients was 89.0 %. The 3-year DMFS rates of IMPC patients was 90.9 % and IDC patients was 89 %. CONCLUSIONS: IMPC had poor clinical characteristics, but it showed no difference in OS, FFS, LRFS, and DMFS compare with IDC.

The expression of CXCL13 and its relation to unfavorable clinical characteristics in young breast cancer.

BACKGROUND: Young breast cancer occupies a higher and higher proportion of breast cancer, especially in Asia, and is associated with a more unfavorable prognosis compared with the disease arising in older women. However, the poor prognosis of young breast cancer cannot be fully explained by the clinical and molecular factors. METHODS: This study investigated 1125 Chinese breast cancer patients diagnosed from 2009 to 2013. A data mining of gene expression profiles was performed for the young and older breast cancer patients, identifying significantly differentially expressed genes. Quantitative RT-PCR, Western blotting and immunohistochemistry assay were carried out for the clinical sample validations. RESULTS: The investigation firstly displayed that young patients (≤45 years) accounted for 47.6 % (535/1125) of breast cancer, and clinically associated with some unfavorable factors related to poor prognosis, such as invasive pathological type, high tumor grade, lymph node positive, ER negative and triple-negative subtype. Subsequently, 553 significantly differentially expressed genes were identified by the data mining. Of them, a set of genes related to immune function were observed to be up-regulated in young patients with breast cancer. Impressively, the CXCL13 (C-X-C motif chemokine 13) expression level showed the most significant difference (FC = 2.64, P = 8.2 × 10(-4)). Furthermore, the validations with clinical samples and correlation analysis demonstrated that CXCL13 was indeed highly expressed in young breast cancer and closely associated with some prognostic factors including lymph node positive and ER negative. CONCLUSION: This is the first to indicate the clinical relevance of CXCL13 to young breast cancer and represents a potential therapeutic target for young breast cancer.

[Advances in studies on metabolic syndrome and breast cancer].

Breast cancer is one of the most common malignancies in women. Over these years, the morbidity of metabolic syndrome (MS) has also been increasing in China, probably due to changes in economies and lifestyles. As a result, the association to between these two diseases has at tracted much attention. Results demonstrated the presence of MS was associated with breast cancer risk, and the risk became higher when more MS components were present compared to no components. Moreover, a specific association was indicated between MS and breast cancer recurrence and metastasis to some extent as well. Further, for breast cancer patients, being diagnosed with MS can increase the mortality and lead to poor prognosis. The mechanisms underlying the association is not clear yet, but several factors are speculated to be the possible causes, including the elevated level of insulin, insulin like growth factor-1, leptin and pro-inflammatory cytokines, the decreased level of adiponectin as well as the interaction between DBC1 and SIRT1. The prognosis of patients with breast cancer combined MS can be improved by means of changing diet habits, increasing physical activities and drug-intervention. Although the specific mechanisms underlying the association are still need to be elucidated, better understanding of the association must help us with new strategies for the prevention and treatment of breast cancer.

miRNA27a is a biomarker for predicting chemosensitivity and prognosis in metastatic or recurrent gastric cancer.

We previously identified five miRNAs (miR-1, miR-20a, miR-27a, miR-34a, and miR-423-5p) that are up-regulated in gastric cancer. The goal of this study was to investigate the value of these miRNAs as potential biomarkers for predicting chemosensitivity and prognosis in metastatic or recurrent gastric cancer patients who received first-line chemotherapy. A total of 82 patients with metastatic or recurrent GC receiving first-line chemotherapy were included in our study. The expression levels of the five miRNAs were evaluated using hydrolysis probe-based stem-loop quantitative reverse transcription polymerase chain reaction (qRT-PCR) in individual samples before first-line chemotherapy. Patients receiving first-line chemotherapy with fluoropyrimidine combined with oxaliplatin or paclitaxel were chosen for the chemosensitivity analysis. The relationships between expression of the five-miRNAs and clinicopathological parameters, response to chemotherapy and prognosis were analyzed statistically. Patients with higher miRNA1 expression levels tended to have a higher rate of liver metastasis, and higher miRNA34a expression levels occurred more frequently in males (P = 0.022). The expression of the remaining three miRNAs showed no obvious relationship to any of the clinicopathological features. The partial response rates of the patients with high miRNA1 expression and low miRNA1 expression were 11.1% and 23.1%, respectively (P = 0.048). Similar results were observed for miRNA27a (the partial response rate was 7.7% vs. 25.9%, P = 0.018). Patients with up-regulated miRNA27a expression had a significantly worse overall survival (OS) than patients with lower miRNA27a expression (P = 0.024). In patients with MRGC, miRNA27a is a potential biomarker for predicting resistance to fluoropyrimidine-based chemotherapy and a novel prognostic marker for gastric cancer.

Risk-association of five SNPs in TOX3/LOC643714 with breast cancer in southern China.

The specific mechanism by which low-risk genetic variants confer breast cancer risk is currently unclear, with contradictory evidence on the role of single nucleotide polymorphisms (SNPs) in TOX3/LOC643714 as a breast cancer susceptibility locus. Investigations of this locus using a Chinese population may indicate whether the findings initially identified in a European population are generalizable to other populations, and may provide new insight into the role of genetic variants in the etiology of breast cancer. In this case-control study, 623 Chinese female breast cancer patients and 620 cancer-free controls were recruited to investigate the role of five SNPs in TOX3/LOC643714 (rs8051542, rs12443621, rs3803662, rs4784227, and rs3112612); Linkage disequilibrium (LD) pattern analysis was performed. Additionally, we evaluated how these common SNPs influence the risk of specific types of breast cancer, as defined by estrogen receptor (ER) status, progesterone receptor (PR) status and human epidermal growth factor receptor 2 (HER2) status. Significant associations with breast cancer risk were observed for rs4784227 and rs8051542 with odds ratios (OR) of 1.31 ((95% confidence intervals (CI), 1.10-1.57)) and 1.26 (95% CI, 1.02-1.56), respectively, per T allele. The T-rs8051542 allele was significantly associated with ER-positive and HER2-negative carriers. No significant association existed between rs12443621, rs3803662, and rs3112612 polymorphisms and risk of breast cancer. Our results support the hypothesis that the applicability of a common susceptibility locus must be confirmed among genetically different populations, which may together explain an appreciable fraction of the genetic etiology of breast cancer.

CHRNA3 polymorphism modifies lung adenocarcinoma risk in the Chinese Han population.

Recent genome-wide association studies (GWASs) have identified 15q25.1 as a lung cancer susceptibility locus. Here, we sought to explore the direct carcinogenic effects of genetic variants in this region on the risk of developing lung adenocarcinoma (ADC). Five common SNPs (rs8034191, rs16969968, rs1051730, rs938682, and rs8042374) spanning the 15q25.1 locus were assayed in a case-control study examining a cohort of 301 lung ADCs and 318 healthy controls. Stratification analysis by gender, smoking status, and tumor, node, metastasis (TNM) classification, was performed. In addition, sections from ADC tissue and normal tissue adjacent to tumors were stained with an anti-CHRNA3 (cholinergic receptor nicotinic α3) antibody by immunohistochemistry in 81 cases. Our results demonstrate that rs8042374, a variant of the CHRNA3 gene, is associated with an increased risk of ADC with an OR of 1.76 (95% CI: 1.17-2.65, p=0.024). This variant was linked to a greater risk of ADC in female nonsmokers (OR (95% CI): 1.81 (1.05-3.12), p=0.032) and female stage I+II cases (OR (95% CI): 1.92 (1.03-3.57), p=0.039). Although located within the same gene, rs938682 showed protective effects for smokers, stage III+IV cases, and male stage III+IV cases. Additionally, the CHRNA3 protein level in ADC tissue was slightly higher than in the surrounding normal lung tissue, based on immunohistochemical analysis. Our results suggest that the CHRNA3 polymorphism functions as a genetic modifier of the risk of developing lung ADC in the Chinese population, particularly in nonsmoking females.

Overcoming the Tumor Collagen Barriers: A Multistage Drug Delivery Strategy for DDR1-Mediated Resistant Colorectal Cancer Therapy.

The extracellular matrix (ECM) is critical for drug resistance in colorectal cancer (CRC). The abundant collagen within the ECM significantly influences tumor progression and matrix-mediated drug resistance (MMDR) by binding to discoidin domain receptor 1 (DDR1), but the specific mechanisms by which tumor cells modulate ECM via DDR1 and ultimately regulate TME remain poorly understand. Furthermore, overcoming drug resistance by modulating the tumor ECM remains a challenge in CRC treatment. In this study, a novel mechanism is elucidated by which DDR1 mediates the interactions between tumor cells and collagen, enhances collagen barriers, inhibits immune infiltration, promotes drug efflux, and leads to MMDR in CRC. To address this issue, a multistage drug delivery system carrying DDR1-siRNA and chemotherapeutic agents is employed to disrupt collagen barriers by silencing DDR1 in tumor, enhancing chemotherapy drugs diffusion and facilitating immune infiltration. These findings not only revealed a novel role for collagen-rich matrix mediated by DDR1 in tumor resistance, but also introduced a promising CRC treatment strategy.

Comprehensive analysis of ALG3 in pan-cancer and validation of ALG3 as an onco-immunological biomarker in breast cancer.

ALG3 has significant modulatory function in the process of tumor development. Yet how ALG3 involves in the advancement of different malignancies isn't fully understood. We performed a pan-cancer assessment on ALG3 utilizing datasets from The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) to examine its tumor-related roles across malignancies and its link to particular molecules and cells in the tumor microenvironment (TME). Furthermore, we focused on breast cancer to examine the influence of ALG3-mediated signaling pathways and intercellular interactions in the advancement of tumors. The biological effects of ALG3 were verified by breast cancer cells. Enhanced ALG3 expression was discovered to be substantially linked to patients' grim prognoses in a number of malignancies. Furthermore, the expression of ALG3 in the TME was linked to the infiltration of stromal and immune cells, and ALG3-related immune checkpoints, TMB, and MSI were also discovered. We also discovered that cancer patients having a high level of ALG3 exhibited a lower probability of benefiting from immunotherapy. Furthermore, our research found that KEGG enrichment, single-cell RNA and spatial sequencing analyses were effective in identifying key signaling pathways in ALG3-associated tumor growth. In vitro, knockdown of ALG3 could decrease the proliferation of breast cancer cells. In summary, our research offers a comprehensive insight into the advancement of tumors under the mediation of ALG3. ALG3 appears to be intimately associated with tumor development in the TME. ALG3 might be a viable treatment target for cancer therapy, particularly in the case of breast cancer.

Nanoreceptors promote mutant p53 protein degradation by mimicking selective autophagy receptors.

In some cancers mutant p53 promotes the occurrence, development, metastasis and drug resistance of tumours, with targeted protein degradation seen as an effective therapeutic strategy. However, a lack of specific autophagy receptors limits this. Here, we propose the synthesis of biomimetic nanoreceptors (NRs) that mimic selective autophagy receptors. The NRs have both a component for targeting the desired protein, mutant-p53-binding peptide, and a component for enhancing degradation, cationic lipid. The peptide can bind to mutant p53 while the cationic lipid simultaneously targets autophagosomes and elevates the levels of autophagosome formation, increasing mutant p53 degradation. The NRs are demonstrated in vitro and in a patient-derived xenograft ovarian cancer model in vivo. The work highlights a possible direction for treating diseases by protein degradation.

Cdc42-driven endosomal cholesterol transport promotes collateral resistance in HER2-positive gastric cancer.

Resistance to trastuzumab and the poor efficacy of subsequent chemotherapy have become major challenges for HER2-positive gastric cancer (GC). As resistance evolves, tumor cells may acquire a new drug susceptibility profile, profoundly impacting the subsequent treatment selection and patient survival. However, the interplay between trastuzumab and other types of drugs in HER2-positive GC remains elusive. In our study, we utilized resistant cell lines and tissue specimens to map the drug susceptibility profile of trastuzumab-resistant GC, discovering that resistance to trastuzumab induces collateral resistance to commonly used chemotherapeutic agents. Additionally, patients with collateral resistance distinguished by a 13-gene scoring model in HER2-positive GC cohorts are predicted to have a poor prognosis and may be sensitive to cholesterol-lowering drugs. Mechanistically, endosomal cholesterol transport is further confirmed to enrich cholesterol in the plasma membrane, contributing to collateral resistance through the Hedgehog-ABCB1 axis. As a driver for cholesterol, Cdc42 is activated by the formation of the NPC1-TßRI-Cdc42 complex to facilitate endosomal cholesterol transport. We demonstrated that inhibiting Cdc42 activation with ZCL278 reduces cholesterol levels in the plasma membrane and reverses collateral resistance between trastuzumab and chemotherapy in vitro and in vivo. Collectively, our findings verify the phenomena and mechanism of collateral resistance between trastuzumab and chemotherapy, and propose a potential therapeutic target and strategy in the second-line treatment for trastuzumab-resistant HER2-positive GC.

MT1-MMP in breast cancer: induction of VEGF-C correlates with metastasis and poor prognosis.

BACKGROUND: Recent evidence suggests that vascular endothelial growth factor-C (VEGF-C)- dependent tumour production promotes lymphangiogenesis, while membrane-type matrix 1 metalloproteinase (MT1-MMP) is involved in the critical steps leading to carcinogenesis. However, the role of MT1-MMP in lymphangiogenesis and lymphatic metastasis remains poorly understood. In the present study, we investigated the relationship between MT1-MMP and VEGF-C in human breast cancer and correlated MT1-MMP and VEGF-C expression with lymphangiogenesis and prognosis. METHODS: MT1-MMP and VEGF-C levels were compared in five breast carcinoma cell lines. We used a membrane invasion assay to assess the effect of MT1-MMP and VEGF-C expression, as well as anti-MT1-MMP and VEGF-C antibodies, on cancer cell invasion. We further assessed MT1-MMP and VEGF-C immunoreactivity and lymph vessels in a cohort of human breast cancer specimens (n = 106) and associated MT1-MMP and VEGF-C expression with clinicopathological parameters, such as lymphatic vessel density (LVD), and patient prognosis. RESULTS: MT1-MMP and VEGF-C expression differed among the five breast cancer cell lines and MT1-MMP and VEGF-C expression were correlated with tumour cell invasion. VEGF-C mRNA expression levels and invasive activity of MDA-MB-231 cells was inhibited by an anti-MT1-MMP antibody in a concentration-dependent manner. A significant correlation was found between the expression of MT1-MMP and VEGF-C in breast cancer patient samples and elevated MT1-MMP and VEGF-C expression was associated with higher LVD, lymph node metastasis, cancer stage, and a decline in overall survival rates. CONCLUSIONS: Our data demonstrate that MT1-MMP expression is closely correlated with VEGF-C expression, and that MT1-MMP promotes lymphangiogenesis by up-regulating VEGF-C expression in human breast cancer. Thus, elevated MT1-MMP may serve as a significant prognostic factor in breast cancer.