Upgrading Berkeley DB rpm in a Centos OS

I have a software which needs Berkeley DB 4.5 or above.

But in my CentOS 5.11 x86_64 Server I have:

• Package db4-4.3.29-10.el5_5.2.x86_64 already installed and latest version
• Package db4-4.3.29-10.el5_5.2.i386 already installed and latest version

How can I upgrade these rpm to a newer version?
I tried to upgrade using Centos 6.6 rpm in this way:

rpm -Uvh ftp://195.220.108.108/linux/centos/6.6/os/x86_64/Packages/db4-4.7.25-18.el6_4.i686.rpm

but I receive this error:

Retrieving ftp://195.220.108.108/linux/centos/6.6/os/x86_64/Packages/db4-4.7.25-18.el6_4.i686.rpm
warning: /var/tmp/rpm-xfer.IKWqHE: Header V3 RSA/SHA1 signature: NOKEY, key ID c105b9de
error: Failed dependencies:
        rpmlib(FileDigests) <= 4.6.0-1 is needed by db4-4.7.25-18.el6_4.i686
        rpmlib(PayloadIsXz) <= 5.2-1 is needed by db4-4.7.25-18.el6_4.i686
        db4 >= 4.4.0 conflicts with pam-0.99.6.2-12.el5.i386
        db4 >= 4.4.0 conflicts with pam-0.99.6.2-12.el5.x86_64
        libdb-4.3.so is needed by (installed) subversion-1.6.11-12.el5_10.i386
        libdb-4.3.so is needed by (installed) pam_ccreds-3-5.i386
        libdb-4.3.so is needed by (installed) apr-util-1.2.7-11.el5_5.2.i386
        libdb-4.3.so is needed by (installed) db4-devel-4.3.29-10.el5_5.2.i386
        libdb_cxx-4.3.so is needed by (installed) db4-devel-4.3.29-10.el5_5.2.i386

I also tried to compile from source db-4.5.20.tar.gz. I compiled it with no problem, however my software is still seeing the Berkley DB preinstalled in rpm package db4-4.3.29.

Any help please ?