Han Sung Kang

Salinomycin sensitizes cancer cells to the effects of doxorubicin and etoposide treatment by increasing DNA damage and reducing p21 protein

Salinomycin (Sal) has recently been shown to inhibit various cancer stem cells. Here, we investigated whether Sal could sensitize cancer cells to the effects of doxorubicin (DOX) or etoposide (ETO).

Salinomycin, a p-glycoprotein inhibitor, sensitizes radiation-treated cancer cells by increasing DNA damage and inducing G2 arrest.

SummarySalinomycin (Sal) is potentially useful for the treatment of cancer. The present study examined a novel mechanism of Sal sensitization in cancer cells. Sal sensitized radiation-treated cancer cells by inducing G2 arrest and causing DNA damage. Sal treatment also reduced p21 levels in radiation-treated cells. Considering that Sal sensitizes doxorubicin (DOX)- or etoposide (ETO)-treated cancer cells by causing DNA damage and reducing p21 expression, the results from our study suggest that the mechanism underlying Sal sensitization is conserved in both chemo- and radiation-treated cells. We also tested the ability of Sal to inhibit p-glycoprotein (P-gp), which plays a role in the efflux of anti-cancer drugs to reduce cellular damage. In particular, we compared Sal to verapamil (Ver), a well-known P-gp inhibitor. Sal inhibits P-gp with a different substrate distinct from that of Ver. In addition, Sal sensitized Ver-resistant cells, indicating that this compound is more effective for sensitizing than Ver. Taken together, the results from our study may contribute to the development of Sal-based therapy for cancer patients treated with P-gp-inhibiting drugs or radiation therapy.

Salinomycin sensitizes antimitotic drugs-treated cancer cells by increasing apoptosis via the prevention of G2 arrest

Here, we investigated whether Sal could sensitize cancer cells to antimitotic drugs. We demonstrated that Sal sensitized paclitaxcel (PAC)-, docetaxcel (DOC)-, vinblastin (VIN)-, or colchicine (COL)-treated cancer cell lines, suggesting that Sal has the ability to sensitize the cells to any form of microtubule-targeting drugs. Sensitization to the antimitotic drugs could be achieved with very low concentrations of Sal, suggesting that there is a possibility to minimize Sal toxicity associated with human cancer patient treatments. Sensitization by Sal increased apoptosis, which was observed by C-PARP production. Sal sensitized the cancer cells to antimitotic drugs by preventing G2 arrest, suggesting that Sal contributes to the induction of mitotic catastrophe. Sal generally reduced cyclin D1 levels in PAC-, DOC-, and VIN-treated cells. In addition, Sal treatment increased pH2AX levels and reduced p21 levels in antimitotic drugs-treated cells. These observations suggest that the mechanisms underlying Sal sensitization to DNA-damaging compounds, radiation, and microtubule-targeting drugs are similar. Our data demonstrated that Sal sensitizes cancer cells to antimitotic drugs by increasing apoptosis through the prevention of G2 arrest via conserved Sal-sensitization mechanisms. These results may contribute to the development of Sal-based chemotherapy for cancer patients treated with antimitotic drugs.

Jnk signaling pathway-mediated regulation of Stat3 activation is linked to the development of doxorubicin resistance in cancer cell lines.

We sought to identify altered transcription factors (Stat, AP1, and NF-kB) or signal proteins (Erk1/2, p38, Akt, Jnk, Jak, and c-Src) in cancer cell lines whose growth was arrested by doxorubicin (DOX) treatment. Jnk1 was the only signal protein to be activated. DOX increased Stat3 phosphorylation, nuclear localization, and transcriptional activity. Jnk1 activation appeared to be required for Stat3 activity. Stat3 activity via the Jnk pathway was conserved in other cell lines originating from other organs. Transcriptional activity of Stat3 was increased in cells surviving DOX treatment suggesting that Stat3 activation contributed to the resistance to cytotoxicity. To better understand the role of Stat3 in Jnk1 activation, we investigated its effect on the viability of DOX-treated cells. Co-treatment with DOX and Jnk inhibitor negatively correlated with the viability of cancer cells and reduced Stat3 activity. Taken together, these results indicate that Stat3 activation via the Jnk pathway promotes the resistance of cancer cells to DOX.

Metaplastic breast cancer: Clinicopathological features and its prognosis

Aims The prognosis of metaplastic breast cancer (MBC) is reportedly worse than that of triple-negative invasive ductal carcinoma (TN-IDC), but the determinants of poor prognosis are not yet known. Methods Patients from two Korean cancer centres were included in this study (67 MBC and 520 TN-IDC). Characteristics of the two disease groups, including clinical parameters, histological features, chemoresponsiveness, disease recurrence and survival estimates, were evaluated. Results MBC presented with larger tumours, more frequent distant metastasis and higher histological grade compared with TN-IDC (p<0.001). All but nine patients with MBC had triple-negative disease. Disease-free survival and overall survival (OS) of MBC were worse than TN-IDC (p<0.001). Multivariable analysis of disease-free survival revealed MBC type as an independent prognostic factor (HR 2.53; 95% CI 1.32 to 4.84) along with lymph node metastasis and implementation of breast conserving surgery. For OS, MBC type remained a significant prognostic factor (HR 2.56; 95% CI 1.18 to 5.54). Chemoresponsiveness of MBC and TN-IDC were similar in both neoadjuvant (p=1.000) and advanced disease settings (p=0.508). For a given MBC type, risk factors for disease recurrence included the presence of a squamous component (HR 4.0; 95% CI 1.46 to 10.99) and lymph node metastasis (HR 4.76; 95% CI 1.67 to 13.60); the risk factor for OS was initial distant metastasis (HR 10.77; 95% CI 2.59 to 44.76). Conclusions MBC had worse survival outcomes compared with TN-IDC. Poor prognosis for MBC was likely caused by frequent recurrence with high initial stage and the unique biology of MBC itself.

Randomized Pilot Test of a Simultaneous Stage-Matched Exercise and Diet Intervention for Breast Cancer Survivors

PURPOSE/OBJECTIVES To investigate the feasibility and preliminary effects of a simultaneous stage-matched exercise and diet (SSED) intervention in breast cancer survivors. DESIGN Randomized, controlled trial. SETTING Oncology outpatient treatment clinics at the National Cancer Center in South Korea. SAMPLE 45 women with breast cancer who completed their cancer therapy. METHODS Participants were assigned to the SSED intervention group (n = 23) or a control group (n = 22). Participants in the SSED group received a 12-week individualized intervention promoting prescribed exercise and a balanced diet through stage-matched telephone counseling and a workbook. MAIN RESEARCH VARIABLES Program feasibility, behavioral outcomes (stage of motivational readiness for exercise and diet, physical activity, and diet quality), and quality-of-life (QOL) outcomes (functioning and global QOL, fatigue, anxiety, and depression). FINDINGS Participant evaluations of the SSED intervention indicated that it was feasible and acceptable. All women felt that the overall intervention contents were appropriate, and 95% believed that the intervention helped to promote healthy behaviors. Objective data also supported the SSED interventions feasibility (i.e., 91% completed the trial and 100% of intervention calls were received). When compared to control, the SSED intervention group showed significantly greater improvement in motivational readiness for exercise and diet, emotional functioning, fatigue, and depression. CONCLUSIONS Preliminary results suggest that the SSED intervention delivered via telephone counseling and workbook is feasible and beneficial for positive behavioral and QOL outcomes. IMPLICATIONS FOR NURSING Nurse-led lifestyle interventions may improve QOL for cancer survivors.

Phase II Parallel Group Study Showing Comparable Efficacy Between Premenopausal Metastatic Breast Cancer Patients Treated With Letrozole Plus Goserelin and Postmenopausal Patients Treated With Letrozole Alone As First-Line Hormone Therapy

PURPOSE Goserelin and letrozole in premenopausal patients can result in clinical outcomes comparable to those obtained by letrozole alone in postmenopausal patients with metastatic breast cancer (MBC). PATIENTS AND METHODS A total of 73 patients with hormone-responsive MBC were included. Of those, 35 premenopausal patients received goserelin (3.6 mg subcutaneously every 28 days) plus letrozole (2.5 mg orally daily), and 38 postmenopausal patients received letrozole alone as their first-line endocrine therapy in a metastatic setting. RESULTS Baseline characteristics were similar in the two groups, except for a younger age (median, 41 v 53.5 years; P < .001) and a shorter disease-free interval (median, 1.8 v 3.3 years; P = .03) in the premenopausal group. Clinical benefit rates were comparable between the two groups (77% v 74%; P = .77). With the median follow-up of 27.4 months, there was no statistical difference in the median time to progression between the two groups (9.5 months [95% CI, 6.4 to 12.1 months] v 8.9 months [95% CI, 6.4 to 13.3 months]). In patients who did not receive bisphosphonate, letrozole +/- goserelin caused a greater loss of bone mineral density at 6 months compared with that of patients receiving bisphosphonate treatment (premenopausal group, -16.7% v 53.9%; P = .002 and postmenopausal group, -13.3% v 17.4%; P = .04 at the lumbar spine). CONCLUSION Clinical efficacies in premenopausal MBC patients with combined letrozole and goserelin therapy were comparable to those in postmenopausal patients treated with letrozole alone. Although letrozole +/- goserelin resulted in a modest increase in bone resorption, concurrent treatment with bisphosphonate could prevent bone loss at 6 months.

SP600125, an inhibitor of Jnk pathway, reduces viability of relatively resistant cancer cells to doxorubicin

We identified four breast cancer cell lines and one stomach cancer cell line resistant to the cytotoxic effects of doxorubicin (DOX) and examined their sensitivity to other chemotherapeutic agents. SP600125, an inhibitor of the Jnk pathway, reduced the cellular viability of all five DOX-resistant cancer cell lines. Jnk1 siRNA also reduced the viability of the one DOX-resistant cell line in which it was tested. Similar results were produced in an in vivo mouse model, in which the volume of tumors derived from the DOX-resistant cell line was reduced more effectively by treatment with SP600125 than by treatment with DOX, whereas those from a DOX-sensitive cell line were reduced only by DOX treatment. Overall, these results may contribute to the development of chemotherapeutic treatments for patients with DOX-resistant tumors.

Prognostic Implications of Tumor-Infiltrating Lymphocytes in Association With Programmed Death Ligand 1 Expression in Early-Stage Breast Cancer.

BACKGROUND The immune system might influence breast cancer (BC) prognosis. However, the relationship between programmed death ligand 1 (PD-L1) and tumor-infiltrating lymphocyte (TIL) profiles remains unclear with respect to BC subtypes. PATIENTS AND METHODS We investigated the relationship between TIL profiles for CD8+ and forkhead box P3-positive (FOXP3+) and PD-L1 expression in primary tumor tissue using immunohistochemistry and the clinical outcomes in 2 patient cohorts at the National Cancer Center: 256 patients diagnosed with early-stage BC from January 2001 to December 2005 and 77 hormone receptor (HR)-negative BC patients diagnosed from January 2006 to December 2008. Clinical data were collected, including HR status, human epidermal growth factor receptor 2 expression, disease-free survival, and overall survival (OS). RESULTS The median patient age was 47 years (range, 28-78), and the median follow-up period was 9.8 years. Of the 333 patients, 186 (55.9%) had HR-positive and 125 (37.5%) had node-positive BC. We found a strong positive correlation between CD8+ TILs and FOXP3+ TILs (P < .001). CD8+ TILs were more abundant in tumors with low PD-L1 expression (P < .001), although no association was found between FOXP3+ TILs and PD-L1 expression. More CD8+ TILs were present in HR-negative than in HR-positive BC (P < .001), and PD-L1 expression was more frequent in HR-positive BC (P < .001). A greater number of CD8+ TILs (increase in quartile) was strongly associated with OS (hazard ratio, 0.61; 95% confidence interval, 0.39-0.95; P = .03) only in HR-negative BC when adjusted for various clinical factors. PD-L1 expression and FOXP3+ TILs did not exhibit such associations. CONCLUSION Higher CD8+ lymphocyte infiltration was related to lower PD-L1 expression and higher FOXP3+ TIL infiltration in BC. Higher CD8+ TIL expression was associated with prolonged survival only in those with HR-negative BC.

Clinicopathological parameters and biological markers predicting non-sentinel node metastasis in sentinel node-positive breast cancer patients

The value of complete axillary lymph node dissection (ALND) has been questioned in invasive breast cancer (IBC) patients with positive sentinel lymph nodes (SLNs) who have no non-sentinel lymph node (NSLN) metastases. Because biological markers have not been systematically studied in this setting, we sought to identify clinicopathological characteristics and biological markers for predicting NSLN metastases in SLN-positive IBC patients. Two hundred and five IBC patients who had at least one positive SLN and received SLN biopsy and ALND were included in our study. We examined the clinicopathological characteristics of their primary tumors, SLNs and NSLNs. We also evaluated the biological markers of the primary tumors by tissue microarray and immunohistochemistry. Of the 205 patients with SLN metastases, 89 patients (43.4%) had additional metastases in NSLNs. The following factors were found to be associated with NSLN metastases: peritumoral lymphovascular invasion (p=0.01), two or more metastatic SLNs (p<0.01), SLN metastasis >2.0 mm (p<0.01) and extra-nodal extension (p<0.01). Primary tumors >2.0 cm showed more NSLN metastases, but the association was statistically insignificant (p=0.08). In contrast, NSLN metastases were not associated with histologic grade, histologic type, presence of extensive intraductal component, presence of high grade ductal carcinoma in situ and number of harvested SLNs. Biological markers such as E-cadherin, CD44, cyclin D1, p21, ER, PR, c-erbB2, p53, Ki-67, luminal (CK7, CK18, CK19) and basal (CK5, p63) markers were not useful predictors of NSLN metastasis in IBC patients with SLN metastases. Multivariate analysis revealed that SLN metastasis >2.0 mm (p=0.01), two or more metastatic SLNs (p=0.03) and extranodal extension (p<0.01) were independent predictors of NSLN metastasis. For the prediction of NSLN metastasis in IBC patients with SLN metastases, light microscopic evaluation of the number, size and extranodal extension of metastatic SLNs by hematoxylin and eosin staining appeared to be critical. However, the biological markers of primary tumor characterized by immunohistochemical staining, such as luminal and basal markers, hormone receptors, E-cadherin, CD44, cyclin D1, p21, c-erb-B2, p53 and Ki-67, did not appear to be helpful predictors.