Source: H. Graetz, History of the Jews, volume II (Philadelphia: Jewish Publication Society of America, 1893) 385-386.
"Akylas became celebrated through his new Greek translation of the Holy Scriptures. The license with which the Christians treated the old Greek version appears to have awakened him to the necessity of a simple but fixed form of translation. As the Christians read the Holy Scriptures at their service, and employed the Alexandrian translation of the so-called Seventy (Septuaginta), they were anxious to deduce from this text numerous references to Christ. They changed various sentences and added others, in order to obtain the desired prophecies about Christ in the Greek text, which they held sacred...The Jews, on the other hand, startled at the alterations made in order to confirm the Christian point of view, did not hesitate to introduce changes of their own in order to remove all apparent allusions to Christ."
Aquila was a second century C.E. figure who translated what became the Masoretic Version of the Hebrew Bible into Greek. According to Graetz, he did so to rid the text of Christian additions.
Were there Christian additions? I've read Jewish apologists who say "yes." Rabbi Toviah Singer, for example, has claimed that the word "parthenos" (virgin) in the LXX of Isaiah 7:14 was written by a Christian, for the purpose of supporting the virgin birth. The Hebrew is actually almah, which means a young woman (the same way that alam means young man).
And there are Christians who claim that Jews expunged the Hebrew Bible of stuff that sounds Christian, stuff that supposedly predicted Jesus. I saw a book that argued this when I was at Harvard Divinity School. I didn't read all of it, and it was popular rather than scholarly. But, again, we see the claim that people have tampered with the Hebrew Bible.
I recently read the Epistle of Barnabas for my daily quiet time, and I often found myself scratching my head and saying, "Barnabas claims he's citing Scripture, but I've never encountered a verse like that before!" For example, Barnabas 12:8-10 states:
"What again saith Moses unto Jesus (Joshua) the son of Nun, when he giveth him this name, as being a prophet, that all the people might give ear to him alone, because the Father revealeth all things concerning His Son Jesus? Moses therefore saith to Jesus the son of Nun, giving him this name, when he sent him as a spy on the land; Take a book in thy hands, and write what the Lord saith, how the Son of God shall cut up by the roots all the house of Amalek in the last days. Behold again it is Jesus, not a son of man, but the Son of God, and He was revealed in the flesh in a figure." (Lightfoot's Apostolic Fathers in English)
What's Barnabas referring to? It appears to be something like Exodus 17:4, which says (in the LXX), "And the Lord said to Moses, Write this for a memorial in a book, and speak this in the ears of Joshua; for I will utterly blot out the memorial of Amalec from under heaven" (Brenton translation). There's nothing about the son of God or the last days, from what I can see.
I'm not sure if the Christians were adding stuff to that verse, since they could have made it more overtly Christian had they so desired. What's in the above verse looks like something a Jew could conceivably write: Jews called the Davidic king the Son of God (Psalm 2; II Samuel 7:14), and there would be a need for him to kill the Amalekites in the last days, since they seem to keep cropping up. Haman was an Agagite, after all (Esther 3:1)!
I guess my point is that there seemed to be flexibility in the biblical text. How much of that was a means of interpretation? I'm not sure. We know that the Jews sort of mixed interpretation and translation, since that's what they did in their targumim (Aramaic translations of the Hebrew Bible).