Mutations in superoxide dismutase 1 (SOD1) are responsible for 20% of familial ALS. Given the gain of toxic function in this dominantly inherited disease, lowering SOD1 mRNA and protein is predicted to provide therapeutic benefit. An early generation antisense oligonucleotide (ASO) targeting SOD1 was identified and tested in a phase I human clinical trial, based on modest protection in animal models of SOD1 ALS. Although the clinical trial provided encouraging safety data, the drug was not advanced because there was progress in designing other, more potent ASOs for CNS application. We have developed next-generation SOD1 ASOs that more potently reduce SOD1 mRNA and protein and extend survival by more than 50 days in SOD1G93A rats and by almost 40 days in SOD1G93A mice. We demonstrated that the initial loss of compound muscle action potential in SOD1G93A mice is reversed after a single dose of SOD1 ASO. Furthermore, increases in serum phospho-neurofilament heavy chain levels, a promising biomarker for ALS, are stopped by SOD1 ASO therapy. These results define a highly potent, new SOD1 ASO ready for human clinical trial and suggest that at least some components of muscle response can be reversed by therapy.

MicroRNAs are master regulators of gene expression and control many biological pathways such as cell growth, differentiation and apoptosis. Deregulation of microRNA expression and activity results in a myriad of diseases including cancer. Recently, several reports have indicated that single nucleotide polymorphisms (SNPs) in microRNAs and microRNA-target sites impact microRNA biology and associate with cancer risk, treatment response and outcome. In this review we will describe these findings and discuss the possible future of utilizing these SNPs as diagnostic and prognostic markers in the clinic.

MicroRNA (miRNA) expression is tightly regulated by several mechanisms, including transcription and cleavage of the miRNA precursor RNAs, to generate a mature miRNA, which is thought to be directly correlated with activity. MiR-34 is a tumour-suppressor miRNA important in cell survival, that is transcriptionally upregulated by p53 in response to DNA damage. Here, we show for the first time that there is a pool of mature miR-34 in cells that lacks a 5′-phosphate and is inactive. Following exposure to a DNA-damaging stimulus, the inactive pool of miR-34 is rapidly activated through 5′-end phosphorylation in an ATM- and Clp1-dependent manner, enabling loading into Ago2. Importantly, this mechanism of miR-34 activation occurs faster than, and independently of, de novo p53-mediated transcription and processing. Our study reveals a novel mechanism of rapid miRNA activation in response to environmental stimuli occurring at the mature miRNA level.

MicroRNAs are short, single-stranded RNAs that arise from a transient precursor duplex. We have identified a novel activity in HeLa cell extracts that can unwind the let-7 microRNA duplex. Using partially purified material, we have shown that microRNA helicase activity requires ATP and has a native molecular mass of ϳ68 kDa. Affinity purification of the unwinding activity revealed co-purification of P68 RNA helicase. Importantly, recombinant P68 RNA helicase was sufficient to unwind the let-7 duplex. Moreover, like its native homolog, P68 RNA helicase did not unwind an analogous small interfering RNA duplex. We further showed that knockdown of P68 inhibited let-7 microRNA function. From our data, we conclude that P68 RNA helicase is an essential component of the let-7 microRNA pathway, and in conjunction with other factors, it may play a role in the loading of let-7 microRNA into the silencing complex.

Purpose An inherited mutation in KRAS (LCS6-variant, rs61764370) results in altered control of the KRAS oncogene. We studied this biomarker’s correlation to anti-EGFR monoclonal Antibody therapy (moAbs) response in metastatic colorectal cancer patients (mCRC) patients. Experimental Design LCS6-variant and KRAS/BRAF mutational status was determined in 512 mCRC patients treated with salvage anti-EGFR moAbs therapy, and findings correlated with outcome. Reporters were tested in colon cancer cell lines to evaluate the differential response of the LCS6-variant allele to therapy exposure. Results 21.2% (109/512) of mCRC patients had the LCS6-variant (TG/GG), which was found twice as frequently in the BRAF mutated versus the wt group (p = 0.03). LCS6-variant patients had significantly longer PFS with anti-EGFR moAbs monotherapy treatment in the whole cohort (16.85 vs 7.85 weeks, p = 0.019) and in the double wt (KRAS and BRAF) patient population (18 vs 10.4 weeks, p = 0.039). Combination therapy (moAbs plus chemotherapy) led to improved PFS and OS for non-variant patients, and brought their outcome to levels comparable to LCS6-variant patients receiving anti-EGFR moAbs monotherapy. Combination therapy did not lead to improved PFS or OS for LCS6-variant patients. Cell line studies confirmed a unique response of the LCS6-variant allele to both anti-EGFR moAbs monotherapy and chemotherapy. Conclusions LCS6-variant mCRC patients have an excellent response to anti-EGFR moAbs monotherapy, without any benefit of additional chemotherapy. These findings further confirm the importance of this mutation as a biomarker of anti-EGFR moAbs response in mCRC patients, and warrant further prospective confirmation.