[Lani]

after a quick perusal of the article you cited by Subik et al I found the following:

We have
confirmed that SKBR-3, AU 565 and BT-474 overexpress
HER2,30 and found that another cell line,
MDA-MD-435, also over-expresses HER2.
Molecular subtypes, originally identified by gene

Table 3. The results of IHC analysis for all breast caner cell lines.
ER PR HER2 CK5/6 EGFR Ki-67 AR Subtype
MDA-MB-231 0 0 0–1+ − 1+ 100% 8 Basal
SKBR-3 0 0 3+ − 2+ 20% 8 HER2
MDA-MB-231-UR 0 0 0–1+ − 3+ 100% 7 Basal
MCF-12A 0 0 0–1+ + 2+ 95% 5 Basal
HBL101 0 0 0–1+ − 1+ 90% 4 Basal
MDA-MD-435 0 0 3+ − 0 80% 6 HER2
MCF-7 6 6 0–1+ − 1+ 90% 7 Luminal A
HS598T 0 0 0–1+ − 1+ 90% 0 Basal
MCF-10A 0 0 0–1+ + 2+ 30% 0 Basal
BT-20 0 0 0–1+ − 2+ 80% 4 Basal
MCF-10F 0 0 0–1+ + 1+ 100% 0 Basal
468 0 0 0 − 3+ 95% 8 Basal
AU 565 0 0 3+ − 1+ 95% 7 HER2
ZR-75- 1 3 4 2+ − 1+ 80% 8 Luminal A
BT-483 0 0 0 − 1+ 95% 4 Basal
BT-474 0 8 3+ − 1+ 70% 7 Luminal B
MDA-MB-453 0 0 0 − 0 80% 8 Unclassfied
Note: For ER, PR and AR, Allred scores were used.; for HER2 and EGFR the scoring system for HER2 was used; for CK5/6, any strong cytoplasmic stain
is considered as positive; and for Ki-67, the% of any intensity of nuclear stain was used.

I think you are confusing presence of any her2 ie, 0-1+, such as you discussed with respect to MCF7-- in some MCF7 with her2 amplification. Presence and amplification are two very different entities with many powers of magnitude difference in her2 content and entirely different behaviors and prognoses.

Looks like a typo may have been made in my original post/what it was based on as MDA-MB-435 is 3+ for her2 whereas MDA-MB-453 is her2-

AU 565 should also be added to the her2+ bc cell lines list.

Hope this corrects and updates this topic on this thread:

Naturally occurring (rather than produced by transfection of other her2- cell lines with her2) her2 + bc cell lines include
SKBr3, BT474, MDA-MB-435, AU 565, MDA-MB-361

MDA-MB 231 was always listed as her2-

Hope this helps