Potential role of group X secretory phospholipase A2 in cyclooxygenase-2-dependent PGE2 formation during colon tumorigenesis

AbstractAlthough the cyclooxygenase-2 (COX-2) pathway of the arachidonic acid cascade has been suggested to play an important role in colon carcinogenesis, there is little information concerning the identity of phospholipase A2 (PLA2) involved in the arachidonic acid release in colon tumors. Here, we compared the potencies of three types of secretory PLA2s (group IB, IIA and X sPLA2s) for the arachidonic acid release from cultured human colon adenocarcinoma cells, and found that group X sPLA2 has the most powerful potency in the release of arachidonic acid leading to COX-2-dependent prostaglandin E2 (PGE2) formation. Furthermore, immunohistological analysis revealed the elevated expression of group X sPLA2 in human colon adenocarcinoma neoplastic cells in concert with augmented expression of COX-2. These findings suggest a critical role of group X sPLA2 in the PGE2 biosynthesis during colon tumorigenesis

A concept of hazardous NEO detection and impact warning system

In 2013, the well-known Chelyabinsk meteor entered the Earth's atmosphere over Chelyabinsk, Russia. It is estimated that the meteor exploded at altitude near 30 km[2], which damaged thousands of buildings and injured a thousand of residents[3–4]. The estimated size of the meteor is approximately 20 m[2]. Because the meteor approached to Earth from Sun direction, no ground-based observatories could not detect until the impact. Considering such situations, the paper proposes a concept to detect Chelyabinsk-class small Near-Earth Objects. The concept addresses a “last-minute” warning system of NEO impact, in the same manner of “Tsunami” warning. To achieve the mission objective, two locations are assumed for the space telescope installation point i.e., Sun-Earth Lagrange point 1, SEL1 and Artificial Equilibrium Point, AEP. SEL1 is one of the natural equilibrium points, on the other hand, AEP is artificially equilibrated point by Sun and Earth gravity, centrifugal force and low-thrust acceleration. The magnitude of the acceleration to keep AEP is sufficiently small near 1 au radius orbit around the Sun i.e., the order of μm/s2 which can be achieved by solar sail. Through some cases of numerical simulations considering the size of NEOs and detector capability, this paper will show the feasibility of the proposed concept