Herbivore-induced tomato plant volatiles lead to the reduction of insecticides susceptibility in Spodoptera litura.

Herbivore-induced plant volatiles (HIPVs) have been associated with plant-plant-herbivorous-natural enemies communication and an enhanced response to the subsequent attack. Spodoptera litura is a serious cosmopolitan pest that has developed a high level of resistance to many insecticides. However, the underlying molecular and biochemical mechanism by which HIPV priming reduces S. litura larval sensitivity to insecticides remains largely unknown. This study was conducted to explore the potential of volatile from undamaged, or artificially damaged, or S. litura-damaged tomato plants on the susceptibility of S. litura to the insecticides beta-cypermethrin indoxacarb and chlorpyrifos. We found that larvae exposed to volatile from S. litura-damaged or artificially damaged tomato plants were significantly less susceptible to the three insecticides than those exposed to volatile from undamaged tomato plants. Elevated activities of detoxifying enzymes [cytochrome P450 monooxygenases (P450s), glutathione S-transferases (GSTs), and esterases (ESTs)], were expressed in S. litura larvae exposed to volatile from S. litura-damaged tomato plants than those exposed to volatile from undamaged tomato plants. Similarly, seven detoxification-related genes [GSTs (SlGSTe1, SlGSTo1, and SlGSTe3) and P450s (CYP6B48, CYP9A40, CYP321A7, and CYP321B1)] in the midgut and fat body of larvae were up-regulated under exposure to volatile from S. litura-damaged tomato plants. Increased volatile organic compounds emissions were detected in the headspace of tomato plants damaged by S. litura compared to the undamaged plants. Collectively, these findings suggest that HIPVs can considerably reduce caterpillar susceptibility to insecticides, possibly through induction-enhanced detoxification mechanisms, and provide valuable information for implementing an effective integrated pest management strategy.

Hsa-miR-34c suppresses growth and invasion of human laryngeal carcinoma cells via targeting c-Met.

MicroRNAs (miRNAs) are small noncoding RNA molecules that negatively modulate gene expression at the post-transcriptional level. A growing number of studies has shown that more and more miRNAs are aberrantly expressed and involved in the pathogenesis of several types of cancers. Here, we report that the down-regulated hsa-miR-34c was also involved in oncogenesis of laryngeal carcinoma. Our studies indicated that hsa-miR-34c functioned as a tumor suppressor which inhibited growth and invasion of human laryngeal carcinoma cells. Furthermore, in our study, an inverse relationship between the expression of hsa-miR-34c and c-Met was identified in 10 paired fresh samples from tumor tissues and adjacent normal tissues. Infection of hsa-miR-34c mediated by lentivirus suppressed the expression of c-Met directly. In addition, introduction of c-Met cDNA lacking 3'-UTR largely abrogated hsa-miR-34c-induced cell growth and invasion inhibition. These findings suggest aberrantly down-regulated hsa-miR-34c is a critical factor that contributes to malignancy in human laryngeal carcinoma by a mechanism involving targeting of c-Met.