her2 overexpression seems to make breast cancer cells insulin-independent

[Lani]

ie they do not require it for growth or survival

Many breast cancer cells do, but once they transform and become her2+ they no longer do, their metabolism changes

Since her2+ breast cancer (we suppose as the cell lines often, but not always reflect behavior in the body) has a different metabolism than other breast cancers, so saying one drug or diet or treatment which helps/worsens ALL BREAST CANCERS (which is what most articles discuss) may not necessarily be true for her2+ bc.

IGFR1 inhibition may be helpful in some her2+ breast cancers which become resistant to hercetin, but we don't necessariy understand the mechanism and there are IRs and IGFRs (insulin receptors and insulin-like growth factor receptors)

Again, it is not a simple story, but the take-home message is her2+ breast cancer may have a metabolism that is different from other breast cancers so look for articles where her2+ breast cancer or cell lines were specifically studied. eg SKBR3, BT-474

Hope this helped!