The exact influence of statins on gefitinib resistance in human non-small cell lung cancer (NSCLC) cells with KRAS mutation alone or KRAS/PIK3CA and KRAS/PTEN comutations remains unclear. This work found that transfection of mutant KRAS plasmids significantly suppressed the gefitinib cytotoxicity in Calu3 cells (wild-type KRAS). Gefitinib disrupted the Kras/PI3K and Kras/Raf complexes in Calu3 cells, whereas not in Calu3 KRAS mutant cells. These trends were corresponding to the expression of pAKT and pERK in gefitinib treatment. Atorvastatin (1 μM) plus gefitinib treatment inhibited proliferation, promoted cell apoptosis, and reduced the AKT activity in KRAS mutant NSCLC cells compared with gefitinib alone. Atorvastatin (5 μM) further enhanced the gefitinib cytotoxicity through concomitant inhibition of AKT and ERK activity. Atorvastatin could interrupt Kras/PI3K and Kras/Raf complexes, leading to suppression of AKT and ERK activity. Similar results were also obtained in comutant KRAS/PTEN or KRAS/PIK3CA NSCLC cells. Furthermore, mevalonate administration reversed the effects of atorvastatin on the Kras/Raf and Kras/PI3K complexes, as well as AKT and ERK activity in both A549 and Calu1 cells. The in vivo results were similar to those obtained in vitro. Therefore, mutant KRAS-mediated gefitinib insensitivity is mainly derived from failure to disrupt the Kras/Raf and Kras/PI3K complexes in KRAS mutant NSCLC cells. Atorvastatin overcomes gefitinib resistance in KRAS mutant NSCLC cells irrespective of PIK3CA and PTEN statuses through inhibition of HMG-CoA reductase-dependent disruption of the Kras/Raf and Kras/PI3K complexes.

Abstract. Aberrant sialylation is closely associated with the malignant phenotype of cancer cells and metastatic potential. However, the precise nature of the molecules in breast cancers has not been unveiled. In this study, we investigated the expression levels of α2,3-sialic acid residues of 50 primary tumor cases, 50 pair-matched lymph node metastasis tumor samples and in the MDA-MB-231, t-47D and McF-7 breast cancer cell lines with different metastatic potential. the expression of α2,3-sialic acid residues was analyzed by histochemistry, cytochemistry and flow cytometry with Maackia amurensis lectin (MAl). the invasion and migration abilities of cells were examined using cell adhesion and transwell in vitro assays. pair-matched lymph node metastasis tumor samples exhibited higher levels of expression of α2,3-sialic acid residues compared to that of primary tumors (p=0.0432). Furthermore, of 38 tumors cases in t1/t2 stages, 31 (81.58%) had weak staining for MAL, which specifically binds to α2,3-sialic acid residues, whereas of 12 tumor cases in t3/t4 stages, only 1 (8.33%) had weak reactions for MAl. the highly metastatic breast cancer cell line MDA-MB-231 exhibited the strongest binding to MAl and the highest expression levels of α2,3-sialic acid residues among the selected cell lines, depending on mrnA expression levels of α2,3-sialyltransferase gene. the adhesion, invasion and migration activities confirmed that MDA-MB-231 exhibited the greater cell adhesion to, migration toward and invasion to Matrigel. taken together, the high expression of α2,3-sialic acid residues in breast cancer was associated with metastatic potential. this property may be important for developing new therapeutic approaches for breast cancer.

Vascular endothelial growth factor (VEGF) is an essential component for angiogenesis, and hypoxia-inducible factor-1α (HIF-1α), which controls the switch of glycolytic and oxidative metabolism, activates the transcription of VEGF. 12-Deoxyphorbol 13-palmitate (DP) is a compound isolated from the roots of Euphorbia fischeriana, and has been revealed to possess anticancer activity. In the present study, we found that DP is an effective inhibitor of VEGF and HIF-1α in MCF-7 cells. DP markedly reduced cell viability as determined by MTT assay. ELISA, western blotting and RT-qPCR assays indicated that DP significantly decreased the protein and mRNA expression of VEGF and the protein expression of HIF-1α, while HIF-1α mRNA remained unchanged. In addition, the entrance of HIF-1α into the nucleus was blocked after DP treatment as detected by immunofluorescence analysis. In a further study, we proved that the effects mentioned above were associated with constitutive interference of the phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway. DP effectively inhibited the phosphorylation of PI3K and its downstream factors p-Akt and p-mTOR, oppositely enhanced the expression of TSC1 (hamartin) and TSC2 (tuberin), which could be reversed by the co-treatment with the PI3K inhibitor wortmannin. Moreover, the addition of wortmanin further downregulated the protein levels of VEGF and HIF-1α. The results revealed that DP inhibited the expression of VEGF and HIF-1α through the PI3K/Akt/mTOR signaling pathway, confirming that DP may be a potential therapeutic candidate for breast cancer.

Breast cancer constitutes an enormous burden in China. A strong familial clustering of breast cancer suggests a genetic component in its carcinogenesis. To examine the genetic predisposition of high mobility group box‐1/receptor for advanced glycation end products (HMGB1/RAGE) pathway to breast cancer, we genotyped six well‐defined polymorphisms in this pathway among 524 breast cancer patients and 518 cancer‐free controls from Heilongjiang province, China. There were no deviations from Hardy–Weinberg equilibrium for all polymorphisms. In single‐locus analysis, the frequency of rs1800624 polymorphism mutant A allele in RAGE gene was significantly higher in patients than in controls (24.52% versus 19.50%, P = 0.006), with the carriers of rs1800624‐A allele being 1.51 times more likely to develop breast cancer relative to those with rs1800624‐GG genotype after adjustment (95% confidence interval or CI: 1.17–1.94, P = 0.001). In HMGB1 gene, haplotype analysis did not reveal any significance, while in RAGE gene, haplotypes C‐T‐A and C‐A‐G (alleles in order of rs1800625, rs18006024, rs2070600) were significantly associated with an increased risk of breast cancer (adjusted OR = 2.72 and 10.35; 95% CI: 1.20–6.18 and 1.58–67.80; P = 0.017 and 0.015 respectively). In further genetic score analysis, per unit and quartile increments of unfavourable alleles were significantly associated with an increased risk of breast cancer after adjustment (odds ratio or OR = 1.20 and 1.26; 95% CI: 1.09–1.32 and 1.12–1.42; P < 0.001 and <0.001 respectively). Our findings altogether demonstrate a significant association between RAGE gene rs1800624 polymorphism and breast cancer risk, and more importantly a cumulative impact of multiple risk associated polymorphisms in HMGB1/RAGE pathway on breast carcinogenesis.

Abstract. Tumor metastasis is the main cause of mortality in cancer patients. However, no effective therapies are currently available to prevent metastasis. Cell adhesion to the extracellular matrix (ECM) is crucial in cancer progression and metastasis. Thus, suppression of cell adhesion may be an effective therapeutic strategy for the prevention of metastasis. In the present study, the anti-adhesion and anti-invasion effects of jolkinolide B, a diterpenoid compound from Euphorbia fischeriana Steud, that were exerted through suppression of β 1 -integrin expression and phosphorylation of focal adhesion kinase (FAK) were examined in human breast cancer MDA-MB-231 cells. Jolkinolide B inhibited the adhesion of MDA-MB-231 cells to fibronectin but not to poly-L-lysine. In addition, jolkinolide B inhibited extracellular signal-regulated kinase (ERK) phosphorylation. U0126, an ERK inhibitor, also suppressed the invasion and adhesion of MDA-MB-231 cells. Overall, the present data demonstrated that jolkinolide B is a novel inhibitor of FAK-mediated signaling pathways that is involved in decreasing cell adhesion and invasion. Mitogen-activated protein kinase/ERK kinase may play a critical role in these effects, indicating that jolkinolide B possesses therapeutic potential for the treatment of breast cancer metastasis.

Euphorbia fischeriana Steud is a traditional Chinese Medicine that is known to possess a variety of anticarcinogenic properties. However, the bioactive constituents in Euphorbia fischeriana Steud and molecular mechanisms underlying this action in cancer treatment remain poorly understood. The present study investigated the chemotherapy activity and molecular targets of Ethyl gallate, which is identified as the major constituent extracted from the roots of Euphorbia fischeriana Steud in breast cancer cell lines in vitro. The results showed Ethyl gallate obviously decreased cell proliferation in MDA-MB-231 and MCF-7 cells in a dose- and time-dependent manner. Highly invasive MDA-MB-231 cells were found to be highly sensitive to treatment. Furthermore, significantly decreased metastatic potential of highly metastatic MDA-MB‑231 cells by Ethyl gallate was identified via the inhibition of cell motility using invasion and migration through a polyethylene terephthalate membrane. Ethyl gallate treatment decreased the activity of matrix metalloproteinase-2 (MMP-2) and MMP-9 by the downregulation of mRNA levels using RT-PCR, enzymes that are critical to tumor invasion. Treatment with Ethyl gallate decreased phosphatidylinositol 3-kinase (PI3K)/Akt and nuclear factor-κB (NF-κB) activation in MDA-MB-231 cells. These results indicate that Ethyl gallate suppresses proliferation and invasion in human breast cancer cells by modulating the PI3K/Akt pathway, which may contribute to inhibiting their downstream targets such as NF-κB p-65, Bcl-2/Bax, and mRNA levels of MMP-2 and MMP-9 in breast cancer cells. Thus, the present study shed new light on Ethyl gallate, an important bioactive constituent of Euphorbia fischeriana Steud, in human breast cancer treatment. The findings may provide basal theories for wide therapeutic application in human breast cancer.

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Shikonin (SHK) has been proven to have a good anti-tumor effect. However, poor water solubility and low bioavailability limit its wide application in clinical practice. In this study, to overcome these drawbacks, RGD-modified shikonin-loaded liposomes (RGD-SSLs-SHK) were successfully prepared. It exhibited excellent physicochemical characteristics including particle size, zeta potential, encapsulation efficiency, and delayed release time. Meanwhile, the targeting activity of the RGD-modified liposomes was demonstrated by flow cytometry and confocal microscopy in the αvβ3-positive MDA-MB-231 cells. Besides exhibiting greater cytotoxicity in vitro, compared with non-targeted shikonin-loaded liposomes (SSLs-SHK), RGD-SSLs-SHK could also evidently induce apoptosis by decreasing the expression of Bcl-2 and increasing the expression of Bax. It could also inhibit cell proliferation, migration, invasion, and adhesion by reducing the expression of MMP-9 and the level of NF-κB p65, but did not affect the expression of MMP-2 in the MDA-MB-231 cells. Therefore, these findings indicated that the strategy to use RGD-modified liposomes as carriers for targeted delivery of shikonin is a very promising approach to achieve breast cancer targeted therapy.