Andrographolide sensitizes glioma to temozolomide by inhibiting DKK1 expression.

BACKGROUND: Temozolomide (TMZ) is the first-line chemotherapeutic drug for gliomas treatment. However, the clinical efficacy of TMZ in glioma patients was very limited. Therefore, it is urgently needed to discover a novel approach to increase the sensitivity of glioma cells to TMZ. METHODS: Western blot, immunohistochemical staining, and qRT-PCR assays were used to explore the mechanisms underlying TMZ promoting DKK1 expression and andrographolide (AND) inhibiting DKK1 expression. HPLC was used to detect the ability of andrographolide (AND) to penetrate the blood-brain barrier. MTT assay, bioluminescence images, magnetic resonance imaging (MRI) and H&E staining were employed to measure the proliferative activity of glioma cells and the growth of intracranial tumors. RESULTS: TMZ can promote DKK1 expression in glioma cells and brain tumors of an orthotopic model of glioma. DKK1 could promote glioma cell proliferation and tumor growth in an orthotopic model of glioma. Mechanistically, TMZ increased EGFR expression and subsequently induced the activation of its downstream MEK-ERK and PI3K-Akt pathways, thereby promoting DKK1 expression in glioma cells. Andrographolide inhibited TMZ-induced DKK1 expression through inactivating MEK-ERK and PI3K-Akt pathways. Andrographolide can cross the blood-brain barrier, the combination of TMZ and andrographolide not only improved the anti-tumor effects of TMZ but also showed a survival benefit in an orthotopic model of glioma. CONCLUSION: Andrographolide can enhance anti-tumor activity of TMZ against glioma by inhibiting DKK1 expression.

Targeting DKK1 enhances the antitumor activity of paclitaxel and alleviates chemotherapy-induced peripheral neuropathy in breast cancer.

Chemotherapy in combination with immunotherapy has gradually shown substantial promise to increase T cell infiltration and antitumor efficacy. However, paclitaxel in combination with immune checkpoint inhibitor targeting PD-1/PD-L1 was only used to treat a small proportion of metastatic triple-negative breast cancer (TNBC), and the clinical outcomes was very limited. In addition, this regimen cannot prevent paclitaxel-induced peripheral neuropathy. Therefore, there was an urgent need for a novel target to enhance the antitumor activity of paclitaxel and alleviate chemotherapy-induced peripheral neuropathy in breast cancer. Here, we found that Dickkopf-1 (DKK1) expression was upregulated in multiply subtypes of human breast cancer specimens after paclitaxel-based chemotherapy. Mechanistic studies revealed that paclitaxel promoted DKK1 expression by inducing EGFR signaling in breast cancer cells, and the upregulation of DKK1 could hinder the therapeutic efficacy of paclitaxel by suppressing the infiltration and activity of CD8+ T cells in tumor microenvironment. Moreover, paclitaxel treatment in tumor-bearing mice also increased DKK1 expression through the activation of EGFR signaling in the primary sensory dorsal root ganglion (DRG) neurons, leading to the development of peripheral neuropathy, which is charactered by myelin damage in the sciatic nerve, neuropathic pain, and loss of cutaneous innervation in hindpaw skin. The addition of an anti-DKK1 antibody not only improved therapeutic efficacy of paclitaxel in two murine subtype models of breast cancer but also alleviated paclitaxel-induced peripheral neuropathy. Taken together, our findings providing a potential chemoimmunotherapy strategy with low neurotoxicity that can benefit multiple subtypes of breast cancer patients.

High-throughput quantitation of serological dimethylarginines by LC/MS/MS: Potential cardiovascular biomarkers for rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic autoimmune disorder characterized by systemic inflammation of the joints and extra-articular tissues. The incidence of cardiovascular disease (CVD) remains the main cause of morbidity and mortality in patients with RA. Despite the development of new therapeutics targeting the articular manifestations, the relief of the cardiovascular burden is still an unmet medical need during the management of RA. So, the early prognosis of RA-associated CVD plays a crucial role in improving the clinical outcomes of RA patients. Recently, circulating dimethylarginines have gained attention as potential biomarkers for CVDs. Here, we present the development and validation of a high-throughput liquid chromatography-tandem mass spectrometric (LC/MS/MS) method for simultaneous quantification of creatinine, arginine, and dimethylarginines in human serum within 2 mins by isotope dilution mass spectrometry. This method employed a protein precipitation method for rapid sample preparation, trichloroacetic acid (TCA)-based ion pairing chromatography for fast analyte separation, and multiple reaction monitoring (MRM) with stable isotope-labeled internal standards (ISs) for simultaneous quantitation. To assure the quality, our method was validated against the FDA guidelines for lower limit of quantitation (0.2 µM), linearity (square of coefficient correlation>0.99), precision (intra-&inter-assay imprecision < 10 %), accuracy (intra-&inter-assay inaccuracy < 10 %), sample preparation recovery (recovery ≥ 90 %), stability (instability < 10 %), matrix effect (signal suppression < 55 %), and carryover ( < 0.01 %). Afterward, we applied the validated method to a retrospective cross-sectional study. We aimed to evaluate the utility of serological dimethylarginines as potential cardiovascular biomarkers in the development of RA-associated CVD. Our results revealed that the serological ratio of asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA), an indicator of physiological arginine methylation status, was significantly elevated in patients with RA. This finding might provide value in detecting CVD to improve clinical outcomes in RA management.