Punjab National Bank (PNB), one of the largest lenders in India, has slashed its benchmark prime lending rate (BPLR) by 50 basis points to 13.5% from the current level of 14%, said chairman, PNB, K.C. Chakrabarty.The state-run bank`s rate cut would be effective from November 1, he added.The bank is also likely to cut its highest deposit rate by 50 basis points to 10% effective December 1, he added further.Shares of the company gained Rs 18.3, or 4.56%, to settle at Rs 420. The total