Qinghuan Xiao

Activation of STAT3 is involved in malignancy mediated by CXCL12-CXCR4 signaling in human breast cancer

The chemokine receptor CXCR4 and signal transducer and activator of transcription 3 (STAT3) play an important role in breast cancer malignancy and metastasis. However, it remains unknown whether STAT3 can be activated by CXCR4 in human breast cancer. The expression levels of CXCR4, STAT3 and p-STAT3 in 208 breast cancer tissues and 26 tumor-adjacent tissues were examined by immunohistochemistry. Flow cytometry, western blot analysis and immunoprecipitation were used to study activation of STAT3 by CXCL12-CXCR4 signaling in human breast cancer cell lines. The expression levels of CXCR4, STAT3 and p-STAT3 were higher in the breast cancer samples than these levels in the tumor-adjacent samples. The combined expression of CXCR4 and p-STAT3 was correlated with TNM stage, tumor size, lymph node metastasis and histological grade of breast cancer. In the breast cancer cells, CXCL12 treatment increased the expression of p-STAT3. The CXCR4 antagonist AMD3100 and the Janus kinase 2 (JAK2) antagonist AG490 inhibited the CXCL12-induced increase in the phosphorylation of STAT3. Furthermore, CXCL12 promoted direct binding of JAK2 to CXCR4. Our findings suggest that activation of the JAK2/STAT3 pathway via CXCL12-CXCR4 signaling plays an important role in breast cancer malignancy and metastasis. Targeting the CXCL12-CXCR4/JAK2/STAT3 signaling pathway may be a potential therapeutic strategy for the treatment of breast cancer.

DNA methyltransferase 1/3a overexpression in sporadic breast cancer is associated with reduced expression of estrogen receptor-alpha/breast cancer susceptibility gene 1 and poor prognosis.

DNA methyltransferases (DNMTs), including DNMT1, 3a, and 3b, play an important role in the progression of many malignant tumors. However, it remains unclear whether expression of DNMTs is associated with the development of breast cancer. This study aimed to explore the clinical significance of DNMT proteins in sporadic breast cancer. We investigated the expression of DNMT1, 3a, and 3b in 256 breast cancer and 36 breast fibroadenoma, using immunohistochemistry. The expression of DNMT1 and 3a was significantly higher in breast cancer than in fibroadenoma. In breast cancer, the expression of DNMT1 was significantly correlated with lymph node metastasis (P = 0.020), and the expression of DNMT3a and 3b was significantly correlated with advanced clinical stages (P = 0.046 and 0.012, respectively). Overexpression of DNMT1/3a was correlated with promoter hypermethylation and reduced expression of ERα and BRCA1. The expression levels of DNMT1 or DNMT3a were associated with a significantly shorter DFS or OS in a subgroup of breast cancer patients (patients with the age ≤50 years old, ERα‐negative status, or HER2‐postive status). The expression of DNMT1 or a combined expression of DNMT1 and 3a was associated with poor prognosis in patients who received chemotherapy and endocrine therapy, but not in patients who received chemotherapy alone. These findings suggest that DNMT1 and 3a may be involved in the progression and prognosis of sporadic breast cancer.

The Hedgehog signalling pathway mediates drug response of MCF-7 mammosphere cells in breast cancer patients

BCSCs (breast cancer stem cells) have been shown to be resistant to chemotherapy. However, the mechanisms underlying BCSC-mediated chemoresistance remain poorly understood. The Hh (Hedgehog) pathway is important in the stemness maintenance of CSCs. Nonetheless, it is unknown whether the Hh pathway is involved in BCSC-mediated chemoresistance. In the present study, we cultured breast cancer MCF-7 cells in suspension in serum-free medium to obtain BCSC-enriched MCF-7 MS (MCF-7 mammosphere) cells. We showed that MCF-7 MS cells are sensitive to salinomycin, but not paclitaxel, distinct from parent MCF-7 cells. The expression of the critical components of Hh pathway, i.e., PTCH (Patched), SMO (Smoothened), Gli1 and Gli2, was significantly up-regulated in MCF-7 MS cells; salinomycin, but not paclitaxel, treatment caused a remarkable decrease in expression of those genes in MCF-7 MS cells, but not in MCF-7 cells. Salinomycin, but not paclitaxel, increased apoptosis, decreased the migration capacity of MCF-7 MS cells, accompanied by a decreased expression of c-Myc, Bcl-2 and Snail, the target genes of the Hh pathway. The salinomycin-induced cytotoxic effect could be blocked by Shh (Sonic Hedgehog)-mediated Hh signalling activation. Inhibition of the Hh pathway by cyclopamine could sensitize MCF-7 MS cells to paclitaxel. In addition, salinomycin, but not paclitaxel, significantly reduced the tumour growth, accompanied by decreased expression of PTCH, SMO, Gli1 and Gli2 in xenograft tumours. Furthermore, the expression of SMO and Gli1 was positively correlated with the expression of CD44+ / CD24-, and the expression of SMO and Gli1 in CD44+ / CD24- tissues was associated with a significantly shorter OS (overall survival) and DFS (disease-free survival) in breast cancer patients receiving chemotherapy.

Association of ABCB1 genetic polymorphisms with susceptibility to colorectal cancer and therapeutic prognosis

AIM To evaluate the association of ABCB1 gene polymorphisms with susceptibility to colorectal cancer (CRC) and clinical outcomes of CRC patients with chemotherapy. PATIENTS & METHODS A case-control study was performed on the C3435T, C1236T and G2677T/A polymorphisms in the ABCB1 gene in 1028 CRC patients and 1230 controls. RESULTS We observed that the ABCB1 C3435T and G2677T/A variants as well as the 3435T-1236T-2677T haplotype significantly increased the risk of CRC. The ABCB1 C3435T CT genotype had a significant effect on the time to recurrence (adjusted hazard ratio [HR; 95% CI]: 0.560 [0.355-0.882]; p = 0.012). Moreover, ABCB1 C1236T variant carriers displayed a longer overall survival after postoperative oxaliplatin-based chemotherapy (adjusted HR [95% CI]: 0.354 [0.182-0.692], 0.646 [0.458-0.910], respectively). In addition, 1236TT-2677TT-3435TT haplotype carriers showed a worse progression-free survival (adjusted HR [95% CI]: 1.477 [1.012-3.802]; p = 0.043) and recurrence-free survival (adjusted HR [95% CI]: 2.183 [1.253-3.802]; p = 0.006). CONCLUSION The ABCB1 polymorphisms might be a candidate pharmacogenomic factor to assess susceptibility and prognosis after oxaliplatin-based chemotherapy for CRC patients.

Salinomycin induces selective cytotoxicity to MCF-7 mammosphere cells through targeting the Hedgehog signaling pathway

Breast cancer stem cells (BCSCs) are believed to be responsible for tumor chemoresistance, recurrence, and metastasis formation. Salinomycin (SAL), a carboxylic polyether ionophore, has been reported to act as a selective breast CSC inhibitor. However, the molecular mechanisms underlying SAL-induced cytotoxicity on BCSCs remain unclear. The Hedgehog (Hh) signaling pathway plays an important role in CSC maintenance and carcinogenesis. Here, we investigated whether SAL induces cytotoxicity on BCSCs through targeting Hh pathway. In the present study, we cultured breast cancer MCF-7 cells in suspension in serum-free medium to obtain breast CSC-enriched MCF-7 mammospheres (MCF-7 MS). MCF-7 MS cells possessed typical BCSC properties, such as CD44+CD24-/low phenotype, high expression of OCT4 (a stem cell marker), increased colony-forming ability, strong migration and invasion capabilities, differentiation potential, and strong tumorigenicity in xenografted mice. SAL exhibited selective cytotoxicity to MCF-7 MS cells relative to MCF-7 cells. The Hh pathway was highly activated in BCSC-enriched MCF-7 MS cells and SAL inhibited Hh signaling activation by downregulating the expression of critical components of the Hh pathway such as PTCH, SMO, Gli1, and Gli2, and subsequently repressing the expression of their essential downstream targets including C-myc, Bcl-2, and Snail (but not cyclin D1). Conversely, Shh-induced Hh signaling activation could largely reverse SAL-mediated inhibitory effects. These findings suggest that SAL-induced selective cytotoxicity against MCF-7 MS cells is associated with the inhibition of Hh signaling activation and the expression of downstream targets and the Hh pathway is an important player and a possible drug target in the pathogenesis of BCSCs.

Expression of BAMBI and its combination with Smad7 correlates with tumor invasion and poor prognosis in gastric cancer

Bone morphogenetic proteins and activin membrane-bound inhibitor (BAMBI) and drosophila mothers against decapentaplegic protein 7 (Smad7) are known to negatively regulate the transforming growth factor-β (TGF-β) signaling and play an important role in the progression of many malignant tumors. However, it remains unclear whether expression of BAMBI alone or in combination with Smad7 is associated with the progression of gastric cancer. In the present study, we investigated the expression of BAMBI and Smad7 in 276 cancer tissues and 263 tumor-adjacent tissues from gastric cancer patients, using tissue-microarray-based immunohistochemistry. The expression of BAMBI and Smad7 was significantly higher in cancer tissues than in tumor-adjacent tissues. The expression of BAMBI was significantly correlated with increased depth of invasion (P = 0.010), lymphatic invasion (P < 0.001), lymph node metastasis (P = 0.001), TNM stage (P = 0.008), and decreased differentiation (P = 0.046). The expression of BAMBI was associated with a significantly shorter overall survival (OS) (P = 0.006) and disease-free survival (DFS) (P = 0.011). The combined expression of BAMBI and Smad7 was associated with more invasion and metastasis as well as less survival time in gastric cancer patients. The univariate analysis showed that the expression of BAMBI alone or in combination with Smad7 was significantly associated with the OS and DFS. These findings suggest that BAMBI and Smad7 may cooperatively inhibit the TGF-β signaling, and thus promote the progression of gastric cancer.

Combined expression of ezrin and E-cadherin is associated with lymph node metastasis and poor prognosis in breast cancer

Ezrin and E-cadherin have been known to play a role in tumor metastasis. However, the association between the expression of ezrin and E-cadherin in breast cancer patients remains unclear. In the present study, we investigated the expression of ezrin and E-cadherin in 275 breast cancer and 80 control patients with benign hyperplasia, using tissue microarray-based immunohistochemistry (IHC). Ezrin expression was higher, while that of E-cadherin was lower in breast cancer than in control samples. Ezrin expression was negatively correlated with E-cadherin expression in a subpopulation of breast cancer patients with a high expression of ezrin [ezrin(high)] and a low expression of E-cadherin [E-cad(low)]. The cytoplasmic expression of E-cadherin [E-cad(c)] occurred significantly more frequently in ezrin(high) breast cancer than in ezrin(low) breast cancer. The expression level of ezrin was significantly higher in breast cancer with E-cad(c) than that with a membrane expression of E-cadherin [E-cad(m)]. Ezrin(high) or E-cad(low) expression was more associated with lymph node metastasis, and shorter overall survival (OS) and disease-free survival (DFS) in breast cancer patients. E-cad(c) was more associated with lymph node metastasis and shorter OS and DFS compared with E-cad(m). The combined expression of ezrin(high) and E-cad(low) or ezrin(high) and ezrin(c) was more associated with lymph node metastasis and poor prognosis. In addition, the multivariate Cox regression analysis revealed that lymph node metastasis and ezrin(high) expression were independent prognostic factors for shorter OS and DFS in breast cancer patients. The results of the present study suggested that ezrin promotes breast cancer metastasis via the regulation of E-cadherin expression.

Ano1/TMEM16A Overexpression Is Associated with Good Prognosis in PR-Positive or HER2-Negative Breast Cancer Patients following Tamoxifen Treatment.

The calcium-activated chloride channel Ano1 (TMEM16A) is overexpressed in many tumors. Although Ano1 overexpression is found in breast cancer due to 11q13 amplification, it remains unclear whether signaling pathways are involved in Ano1 overexpression during breast cancer tumorigenesis in vivo. Estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) have been known to contribute to breast cancer progression. It is unclear whether Ano1 is associated with clinical outcomes in breast cancer patients with different ER, PR and HER2 status. In the present study, we investigated the Ano1 expression in 431 patients with invasive ductal breast carcinoma and 46 patients with fibroadenoma, using immunohistochemistry, and analyzed the association between Ano1 expression and clinical characteristics and outcomes of breast cancer patients with different ER, PR, and HER2 status. Ano1 was overexpressed in breast cancer compared with fibroadenoma. Ano1 was significantly more associated with breast cancer with the lower clinical stage (stage I or II), or triple-negative status. Mostly importantly, Ano1 overexpression was associated with good prognosis in patients with the PR-positive or HER2-negative status, and in patients following tamoxifen treatment. Multivariate Cox regression analysis showed that Ano1 overexpression was a prognostic factor for longer overall survival in PR-positive or HER2-negative patients, and a predictive factor for longer overall survival in patients following tamoxifen treatment. Our findings suggest that Ano1 may be a potential marker for good prognosis in PR-positive or HER2-negative patients following tamoxifen treatment. The PR and HER2 status defines a subtype of breast cancer in which Ano1 overexpression is associated with good prognosis following tamoxifen treatment.

Genetic Variations in ABCG2 Gene Predict Breast Carcinoma Susceptibility and Clinical Outcomes after Treatment with Anthracycline-Based Chemotherapy

The genetic variants of the ATP-binding cassette, subfamily G, member 2 (ABCG2) are known to be involved in developing cancer risk and interindividual differences in chemotherapeutic response. The polymorphisms in ABCG2 gene were genotyped by using PCR-RFLP assays. We found that ABCG2 G34A GA/AA genotype, C421A AA genotype, and haplotypes 34A-421C and 34G-421A were significantly associated with increased risk for developing breast carcinoma. Furthermore, ABCG2 C421A AA homozygote had a significant enhanced therapeutic response in patients with neoadjuvant anthracycline-based chemotherapy. Moreover, ABCG2 G34A AA genotype carriers displayed a longer OS in ER positive patients or PR positive patients after postoperative anthracycline-based chemotherapy. These results suggested that the ABCG2 polymorphisms might be a candidate pharmacogenomic factor to assess susceptibility and prognosis for breast carcinoma patients.

Adenomatous polyposis coli determines sensitivity to the EGFR tyrosine kinase inhibitor gefitinib in colorectal cancer cells

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) have been used to treat colorectal cancer (CRC). However, resistance to EGFR-TKIs presents a great challenge for the treatment of CRC, and the mechanisms of resistance are poorly understood. The adenomatous polyposis coli (APC) protein has been known to contribute to the carcinogenesis of CRC. However, its role in the sensitivity of CRC cells to gefitinib has not been investigated. Human CRC HCT-116 (wild-type APC) and HT-29 (mutant APC) cells were used to investigate the effect of APC on the sensitivity of CRC cells to gefitinib. The MTT assay was used to measure cell viability after exposure to gefitinib. Cell apoptosis, migration and invasion were determined by flow cytometry, wound healing assay and transwell assay, respectively. Knockdown and overexpression of APC were performed, and activation of the EGFR and its downstream pathway was determined. Gefinitib inhibited viability, promoted apoptosis, and reduced the migration of HCT-116 and HT-29 cells. HT-29 cells exhibited increased sensitivity to gefinitib when compared to HCT-116 cells. Knockdown of APC expression increased the sensitivity of HCT-16 cells to gefitinib, accompanied by downregulation of pEGFR, p-AKT and pERK1/2. In contrast, overexpression of APC decreased the sensitivity of HT-29 cells to gefitinib, accompanied by upregulation of pEGFR, p-AKT and pERK1/2. APC plays an important role in the sensitivity of CRC cells to gefitinib. APC may represent a potential therapeutic target for the treatment of CRC.