BackgroundTrastuzumab resistance is almost inevitable in the management of human epidermal growth factor receptor (HER) 2 positive breast cancer, in which phosphatase and tensin homolog deleted from chromosome 10 (PTEN) loss is implicated. Since metadherin (MTDH) promotes malignant phenotype of breast cancer, we sought to define whether MTDH promotes trastuzumab resistance by decreasing PTEN expression through an NFκB-dependent pathway.MethodsThe correlations between MTDH and PTEN expressions were analyzed both in HER2 positive breast cancer tissues and trastuzumab resistant SK-BR-3 (SK-BR-3/R) cells. Gene manipulations of MTDH and PTEN levels by knockdown or overexpression were utilized to elucidate molecular mechanisms of MTDH and PTEN implication in trastuzumab resistance. For in vivo studies, SK-BR-3 and SK-BR-3/R cells and modified derivatives were inoculated into nude mice alone or under trastuzumab exposure. Tumor volumes, histological examinations as well as Ki67 and PTEN expressions were revealed.ResultsElevated MTDH expression indicated poor clinical benefit, shortened progression free survival time, and was negatively correlated with PTEN level both in HER2 positive breast cancer patients and SK-BR-3/R cells. MTDH knockdown restored PTEN expression and trastuzumab sensitivity in SK-BR-3/R cells, while MTDH overexpression prevented SK-BR-3 cell death under trastuzumab exposure, probably through IκBα inhibition and nuclear translocation of p65 which subsequently decreased PTEN expression. Synergized effect of PTEN regulation were observed upon MTDH and p65 co-transfection. Forced PTEN expression in SK-BR-3/R cells restored trastuzumab sensitivity. Furthermore, decreased tumor volume and Ki67 level as well as increased PTEN expression were observed after MTDH knockdown in subcutaneous breast cancer xenografts from SK-BR-3/R cells, while the opposite effect were found in grafts from MTDH overexpressing SK-BR-3 cells.ConclusionsMTDH overexpression confers trastuzumab resistance in HER2 positive breast cancer. MTDH mediates trastuzumab resistance, at least in part, by PTEN inhibition through an NFκB-dependent pathway, which may be utilized as a promising therapeutic target for HER2 positive breast cancer.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2407-14-869) contains supplementary material, which is available to authorized users.

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Alternol is a novel compound purified from the fermenting products by microorganisms named as Alternaria alternata var. monosporus from the bark of Yew. In this study, we tested its effect on mouse lymphocyte leukemia L1210 cells. Alternol was found to inhibit the proliferation and induce apoptosis in L1210 cells. When the cells were treated with Alternol, chromatin condensation and phosphatidylserine externalization were observed with the down-regulation of the pro-survival gene Bcl-2 and the activation of caspase-3, caspase-9, but not caspase-8. Moreover, exposure of cells to Alternol resulted in a significant increase in reactive oxygen species (ROS) and mitochondrial transmembrane potential (DeltaPsim) depolarization. Taken together, these results demonstrate that Alternol is a potent agent in inducing L1210 cells to apoptosis, which involve caspase activation and ROS generation.

To investigate the potential role of small breast epithelial mucin (SBEM) as a marker for detecting hematogenous micrometastasis in breast cancer and explore its clinical significance in neoadjuvant chemotherapy. SBEM protein expression in 82 tissue specimens of primary breast cancer was detected using immunohistochemistry (IHC), and SBEM expression in peripheral blood (PB) samples of 109 primary breast cancer patients (94 cases at stage I-III, 15 cases at stage IV) was detected by flow cytometry (FCM) and reverse transcription polymerase chain reaction (RT-PCR). Moreover, SBEM mRNA expression was monitored by quantification real-time PCR (QPCR) before and after 3 cycles' neoadjuvant chemotherapy. SBEM expression correlated with tumor node metastasis (TNM) staging and lymph node metastasis at both mRNA and protein levels. SBEM expression in PB of breast cancer patients was markedly higher than that of healthy donors and other cancer patients. SBEM was found expressed in PB of 50 cases among 94 cases at stage I-III and expressed in PB of 11 cases among 15 cases at stage IV. After 3 cycles' neoadjuvant chemotherapy, SBEM expression levels were significantly down-regulated in up to 58% breast cancer patients. SBEM has the potential to be a specific marker for predicting hematogenous micrometastasis and response to neoadjuvant chemotherapy in breast cancer.

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HECT domain and ankyrin repeat containing E3 ubiquitin protein ligase 1 (HACE1) is frequently downregulated or lost in numerous types of cancer, including liver cancer. The aim of the present study was to examine whether demethylation of the HACE1 gene could inhibit tumour progression. The expression of HACE1 was detected in liver cancer cell lines. Clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated (Cas)-based demethylation single guide RNAs for the HACE1 gene promoter were designed and transfected into liver cancer cells. Subsequently, proliferation was detected by MTT and colony formation assays, and optineurin (OPTN) ubiquitination and microtubule-associated proteins 1A/1B light chain 3B protein levels were detected by immunoblotting. The levels of HACE1 were significantly reduced in liver cancer cell lines compared with in a normal liver cell line. Demethylation of the HACE1 gene promoter increased HACE1 expression, inhibited the proliferation of liver cancer cells, and promoted OPTN ubiquitination and autophagy activity in liver cancer cells. In conclusion, activation of HACE1 expression by promoter demethylation may provide a suitable approach for anticancer therapy.

Breast cancer metastasis to the stomach is relatively rare. Unlike infiltrating ductal carcinoma, invasive lobular carcinoma (ILC) has a high tendency to metastasize to the stomach. The present study reports a case of a 53-year-old female who had undergone a modified radical mastectomy of the left breast for ILC eight years previously and presented at the clinic seeking treatment for epigastric discomfort from sour regurgitation and belching that had persisted for one month. Gastroscopy revealed multiple apophysis lesions in the stomach, which were diagnosed as metastatic tumors to the stomach. The diagnosis was further established using histological and immunohistochemical analyses for gross cystic disease fluid protein-15, cytokeratin (CK) 7 and CK20. The patient was treated with systemic chemotherapy without surgery. During the treatment, two gastroscopy procedures revealed that the apophysis lesions in the gastric body had narrowed significantly. Few cases of breast cancer metastasizing to the stomach have been reported, particularly those that have been confirmed using gastroscopy. The present study reports a case of breast cancer metastasis to the stomach to raise awareness of the condition.