Repurposing hyperpolarization-activated cyclic nucleotide-gated channels as a novel therapy for breast cancer.

Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are members of the voltage-gated cation channel family known to be expressed in the heart and central nervous system. Ivabradine, a small molecule HCN channel-blocker, is FDA-approved for clinical use as a heart rate-reducing agent. We found that HCN2 and HCN3 are overexpressed in breast cancer cells compared with normal breast epithelia, and the high expression of HCN2 and HCN3 is associated with poorer survival in breast cancer patients. Inhibition of HCN by Ivabradine or by RNAi, aborted breast cancer cell proliferation in vitro and suppressed tumour growth in patient-derived tumour xenograft models established from triple-negative breast cancer (TNBC) tissues, with no evident side-effects on the mice. Transcriptome-wide analysis showed enrichment for cholesterol metabolism and biosynthesis as well as lipid metabolism pathways associated with ER-stress following Ivabradine treatment. Mechanistic studies confirmed that HCN inhibition leads to ER-stress, in part due to disturbed Ca2+ homeostasis, which subsequently triggered the apoptosis cascade. More importantly, we investigated the synergistic effect of Ivabradine and paclitaxel on TNBC and confirmed that both drugs acted synergistically in vitro through ER-stress to amplify signals for caspase activation. Combination therapy could suppress tumour growth of xenografts at much lower doses for both drugs. In summary, our study identified a new molecular target with potential for being developed into targeted therapy, providing scientific grounds for initiating clinical trials for a new treatment regimen of combining HCN inhibition with chemotherapy.

Genetic and clonal dissection of osteosarcoma progression and lung metastasis.

Osteosarcoma is a primary malignant bone tumor that has a high potential to metastasize to lungs. Little is known about the mechanisms underlying the dissemination of OS cancer cells to lungs. We performed whole exome sequencing of 13 OS primary tumors, with matched lung metastases and normal tissues. Phylogenetic analyses revealed that lung metastatic tumors often harbor clones that are nonexistent or rare in the matched primary OS tumors. Spatially and temporally separated lung metastases were from parallel seeding events with a polyphyletic pattern. Loss of TP53 or RB1 is among the early events during OS tumorigenesis, while loss of PTEN is involved at the later stages associated with lung metastases. Finally, KEAP1 was identified as a novel biomarker for increased metastatic risk. Patients whose primary tumors harbored KEAP1 amplification have significantly poorer lung-metastasis free survival. This finding was validated in two independent datasets. Further, in vitro experiments exhibited that KEAP1 depletion suppressed the invasion of OS cells. Our findings uncover the patterns of clonal evolution during OS progression and highlight KEAP1 as a novel candidate associated with the risk of lung metastasis in OS patients.

Helicobacter pylori vacA Genotypes in Chronic Gastritis and Gastric Carcinoma Patients from Macau, China.

Helicobacter pylori is the major triggering factor for gastric carcinoma, but only a small proportion of infected patients develop this disease. Differences in virulence observed among H. pylori strains, namely in the vacuolating cytotoxin vacA gene, may contribute to this discrepancy. Infection with vacA s1, i1 and m1 strains increases the risk for progression of gastric premalignant lesions and for gastric carcinoma. However, in East Asian countries most of the H. pylori strains are vacA s1, regardless of the patients' clinical status, and the significance of the vacA i1 and m1 genotypes for gastric carcinoma in this geographic area remains to be fully elucidated. The aim of the present study was to investigate this relationship in 290 patients from Macau, China. Using very sensitive and accurate genotyping methods, we detected infection with vacA i1 and with vacA m1 strains in, respectively, 85.2% and 52.6% of the patients that were infected with single genotypes. The prevalence of cagA-positive strains was 87.5%. No significant associations were observed between vacA genotypes or cagA and gastric carcinoma. It is worth noting that 37.5% of the infected patients had coexistence of H. pylori strains with different vacA genotypes. Additional studies directed to other H. pylori virulence factors should be performed to identify high risk patients in East Asia.

Distribution of human papillomavirus genotypes among cervical intraepithelial neoplasia and invasive cancers in Macao.

Macao is a densely populated city situated in East Asia where a relatively high prevalence of human papillomavirus (HPV) types 52 and 58 has been reported in women with invasive cervical cancer. To provide data for a population-specific estimation on the impact of HPV vaccines, paraffin-embedded tissues collected from women with invasive cervical cancer or cervical intrapeitheilal neoplasia grade 2 or 3 confirmed histologically were examined for HPV using the INNO-LiPa kit. Of the 35 HPV-positive patients with invasive cancer, one HPV type was detected in 68.6%, and 31.4% were co-infected with more than one HPV type. Overall, HPV 16, HPV 18, HPV 52, and HPV 54 were the most common types found respectively in 57.1%, 17%, 11.4%, and 8.5% of patients with invasive cervical cancer. Among the 59 HPV-positive patients with cervical intraepithelial neoplasia grade 2/3, 55.9% hardbored one HPV type, and 44.1% had co-infections. The common HPV types found included HPV 16 (52.5%), HPV 52 (23.7%), HPV 58 (18.7%), and HPV 33 (17%). Although HPV 11 (a low-risk type) was also found commonly in invasive cervical cancers (14.3%) and cervical intraepithelial neoplasia grade 2/3 (15.3%), the fact that they all existed as co-infections with another high-risk type suggested HPV 11 was not the cause of the lesion. The current vaccines targeting HPV 16/18 are expected to cover 62.9-74.3% of invasive cervical cancers and 32.2-55.9% of cervical intraepithelial neoplasia 2/3 in Macao. Widespread HPV vaccination is expected to reduce substantially the disease burden associated with cervical neoplasia in Macao.