In the first part of the paper, we show that if ω ≤ κ < λ are cardinals, κ <κ = κ, and λ is weakly compact, then in V [M(κ, λ)] the tree property at λ = κ ++V [M(κ,λ)] is indestructible under all κ + -cc forcing notions which live in V [Add(κ, λ)], where Add(κ, λ) is the Cohen forcing for adding λ-many subsets of κ and M(κ, λ) is the standard Mitchell forcing for obtaining the tree property at λ. This result has direct applications to Prikry-type forcing notions and generalized cardinal invariants. In the second part, we assume that λ is supercompact and generalize the construction and obtain a model V * , a generic extension of V , in which the tree property at (κ ++ ) V * is indestructible under all κ + -cc forcing notions living in V [Add(κ, λ)], and in addition by all forcing notions living in V * which are κ + -closed and "liftable" in a prescribed sense (such as κ ++ -directed closed forcings or well-met forcings which are κ ++ -closed with the greatest lower bounds).