Regulation of miR-19 to breast cancer chemoresistance through targeting PTEN.

PURPOSE: To explore whether miR-19 is involved in the regulation of multidrug resistance (MDR), one of the main causes of breast cancer mortality, and modulates sensitivity of tumor cells to chemotherapeutic agents. METHODS: We analyzed miRNA expression levels in three MDR cell lines in comparison with their parent cell line, MCF-7, using a miRNA microarray. We investigated whether inhibitor of miR-19 sensitized MDR cells to chemotherapeutic agents in vitro and in vivo. RESULTS: MiR-19 was overexpressed in all three MDR cell lines compared to their parental cell line, MCF-7. Expression levels of miR-19 in MDR cells were inversely consistent with those of PTEN. Inhibitor of miR-19a restored sensitivity of MDR cells to cytotoxic agents; administration of LNA-antimiR-19a, a chemo-modified miR-19a inhibitor, sensitized MDR cells to chemotherapeutic agents in vivo. CONCLUSION: Our findings demonstrate, for the first time, involvement of miR-19 in multidrug resistance through modulation of PTEN and suggest that miR-19 may be a potential target for preventing and reversing MDR in tumor cells.

Virologic outcome among patients receiving antiretroviral therapy at five hospitals in Haiti.

INTRODUCTION: Viral load (VL) assessment is the preferred method for diagnosing and confirming virologic failure for patients on antiretroviral therapy (ART). We conducted a retrospective cross-sectional study to evaluate the virologic suppression rate among patients on ART for ≥6 months in five hospitals around Port-au-Prince, Haiti. METHODS: Plasma VL was measured and patients with VL <1,000 copies/mL were defined as virologically suppressed. A second VL test was performed within at least six months of the first test. Factors associated with virologic suppression were analyzed using logistic regression models accounting for site-level clustering using complex survey procedures. RESULTS: Data were analyzed for 2,313 patients on ART for six months or longer between July 2013 and February 2015. Among them, 1,563 (67.6%) achieved virologic suppression at the first VL test. A second VL test was performed within at least six months for 718 (31.0%) of the patients. Of the 459 patients with an initial HIV-1 RNA <1,000 copies/mL who had a second VL performed, 394 (85.8%) maintained virologic suppression. Virologic suppression was negatively associated with male gender (adjusted odds ratio [aOR]: 0.80, 95% CI: 0.74-0.0.86), 23 to 35 months on ART (aOR:0.72[0.54-0.96]), baseline CD4 counts of 201-500 cells/mm3 and 200 cells/mm3 or lower (aORs: 0.77 [0.62-0.95] and 0.80 [0.66-0.98], respectively), poor adherence (aOR: 0.69 [0.59-0.81]), and TB co-infection (aOR: 0.73 [0.55-0.97]). CONCLUSIONS: This study showed that over two-thirds of the patients in this evaluation achieved virologic suppression after ≥ six months on ART and the majority of them remained suppressed. These results reinforce the importance of expanding access to HIV-1 viral load testing in Haiti for monitoring ART outcomes.

Utilization of dried blood spot specimens can expedite nationwide surveillance of HIV drug resistance in resource-limited settings.

INTRODUCTION: Surveillance of HIV drug resistance (HIVDR) is crucial to ensuring the continued success of antiretroviral therapy (ART) programs. With the concern of reduced genotyping sensitivity of HIV on dried blood spots (DBS), DBS for HIVDR surveillance have been limited to ART-naïve populations. To investigate if DBS under certain conditions may also be a feasible sample type for HIVDR testing in ART patients, we piloted nationwide surveys for HIVDR among ART patients using DBS in two African countries with rapid scale-up of ART. METHODS: EDTA-venous blood was collected to prepare DBS from adult and pediatric ART patients receiving treatment during the previous 12-36 months. DBS were stored at ambient temperature for two weeks and then at -80°C until shipment at ambient temperature to the WHO-designated Specialized HIVDR Laboratory at CDC in Atlanta. Viral load (VL) was determined using NucliSENS EasyQ® HIV-1 v2.0 kits; HIVDR genotyping was performed using the ATCC HIV-1 Drug Resistance Genotyping kits. RESULTS: DBS were collected from 1,368 and 1,202 ART patients; 244 and 255 these specimens had VL ≥1,000 copies/mL in Kenya and Tanzania, respectively. The overall genotyping rate of those DBS with VL ≥1,000 copies/mL was 93.0% (95% CI: 89.1%-95.6%) in Kenya and 91.8% (87.7%-94.6%) in Tanzania. The turnaround times for the HIVDR surveys from the time of collecting DBS to completing laboratory testing were 6.5 months and 9.3 months for the Kenya and Tanzania surveys, respectively. CONCLUSIONS: The study demonstrates a favorable outcome of using DBS for nationwide surveillance of HIVDR in ART patients. Our results confirm that DBS collected and stored at ambient temperature for two weeks, and shipped with routine courier services are a reliable sample type for large-scale surveillance of acquired HIVDR.

Involvement of miR-326 in chemotherapy resistance of breast cancer through modulating expression of multidrug resistance-associated protein 1.

Multidrug resistance-associated protein (MRP-1/ABCC1) transports a wide range of therapeutic agents and may play a critical role in the development of multidrug resistance (MDR) in tumor cells. However, the regulation of MRP-1 remains controversial. To explore whether miRNAs are involved in the regulation of MRP-1 expression and modulate the sensitivity of tumor cells to chemotherapeutic agents, we analyzed miRNA expression levels in VP-16-resistant MDR cell line, MCF-7/VP, in comparison with its parent cell line, MCF-7, using a miRNA microarray. MCF-7/VP overexpressed MRP-1 mRNA and protein not MDR-1 and BCRP. miR-326 was downregulated in MCF-7/VP compared to MCF-7. Additionally, miR-326 was downregulated in a panel of advanced breast cancer tissues and consistent reversely with expression levels of MRP-1. Furthermore, the elevated levels of miR-326 in the mimics-transfected VP-16-resistant cell line, MCF-7/VP, downregulated MRP-1 expression and sensitized these cells to VP-16 and doxorubicin. These findings demonstrate for the first time the involvement of miRNAs in multidrug resistance mediated by MRP-1 and suggest that miR-326 may be an efficient agent for preventing and reversing MDR in tumor cells.