Tokyo stocks opened lower Friday as investors remained cautious before the conclusion later in the day of the Bank of Japan’s two-day policy meeting. In the first 15 minutes of trading, the 225-issue Nikkei Stock Average fell 70.92 points, or 0.18 percent, from Thursday to 38,649.55. The broader Topix index was down 3.33 points, or 0.12 percent, at 2,728.45. On the top-tier Prime Market, decliners were led by transportation equipment, pharmaceutical and insurance shares. At 9 a.m., the U.S. dollar fetched 157.11-14 yen compared with 156.98-157.08 yen in New York and 157.26-28 yen in Tokyo at 5…