Sprint Corp, the No. 3 U.S. mobile provider, on Tuesday reported an increase in quarterly revenue that was in line with analysts expectations and said it lost wireless subscribers in the first quarter. The company, which is 80 percent owned by Japans SoftBank Corp, said its operating losses narrowed to $151 million, or 0.04 cents per share, in the first quarter, from $643 million, or 21 cents per share, in the year-ago quarter. Revenue rose to $8.88 billion from $8.8 billion, matching the average analyst estimate according to Thomson Reuters I/B/E/S. (Reporting by Marina Lopes;