Using the MMTV -
PyMT mouse breast cancer model, which spontaneously metastasizes to the lungs, Malanchi and colleagues reported that only the CSC population, identified as CD24 + CD90 +, were capable of initiating lung metastases and secondary metastases (Guy et al., 1992; Lin et al., 2003; Malanchi et al., 2012).
This experiment examines the requirement of POSTN in metastatic colonization using the MMTV -
PyMT mouse model.
The functional necessity of POSTN was investigated by observing the pulmonary metastatic potential in POSTN - knockout MMTV -
PyMT mice, which showed a statistically significant decrease compared to controls (Malanchi et al., 2012).
(B) Representative images of the excised tumours and lung metastatic nodules (black arrows) from 4 - month - old Slc6a14 + / + /
PyMT mice and Slc6a14 − / − /
PyMT mice.
Not exact matches
Breed MMTV -
PyMT + / tg; Postn + / − or MMTV -
PyMT + / tg; Postn − / − male
mice with Postn + / + and Postn − / − female
mice to obtain MMTV -
PyMT + / tg; Postn + / + control and MMTV -
PyMT + / tg; Postn − / − experimental female
mice, respectively.
b. For generation of the MMTV -
PyMT + / tg; Postn − / − experimental female
mice, male MMTV -
PyMT + / tg; Postn − / − male
mice will be crossed with Postn − / − female
mice.
Immediately after counting macrometastasis, use the first six lungs identified from MMTV -
PyMT + / tg; Postn + / + female
mice that are positive with metastatic disease for further analysis (Protocol 2).
2) The two repeated experiments analyze the source of POSTN expression in the lung and whether it affects the number / size of primary and secondary tumor formation in a spontaneous
mouse model of breast cancer (MMTV -
PyMT).
◯ Number of pulmonary macrometastases in MMTV -
PyMT + / tg; Postn + / +
mice relative to MMTV -
PyMT + / tg; Postn − / −
mice.
a. Do not use MMTV -
PyMT female
mice for breeding as they develop mammary tumors.
Female
mice carrying the MMTV -
PyMT transgene that are either Postn + / + or Postn − / − will be examined for changes in primary tumor size and the number of spontaneously formed pulmonary macrometastases, which is a replication of the experiment reported in Figures 3A, 3B, and Supplemental Figure 13.
Additionally, they examine MMTV -
PyMT control or POSTN null
mice to test the effect of POSTN on primary tumor growth and metastasis (Figures 3A, 3B, and S13; Malanchi et al., 2012).
Monitor MMTV -
PyMT + / tg; Postn + / + and MMTV -
PyMT + / tg; Postn − / − female
mice for tumor development and keep until tumor disease is fully developed and the metastatic disease is estimated to occur.
The MDC researchers therefore studied
mice which carried the breast cancer gene
PyMT.
MMTV -
PyMT + / tg; Postn − / −
mice and their Postn + / + counterparts were analyzed for primary tumor formation and metastasis.
c. For generation of the MMTV -
PyMT + / tg; Postn + / + control female
mice, the MMTV -
PyMT + / tg; Postn + / − male
mouse will be crossed to Postn + / + female
mice to obtain MMTV -
PyMT + / tg; Postn + / + male
mice that will then be crossed with Postn + / + female
mice.
The first experiment is to measure metastatic lung cancer in MMTV -
PyMT transgenic
mice crossed with the POSTN Knock out
mice, and controls, with focus on the role of periostin in metastatic progression.
PyMT - Tg female
mice typically develop tumours at the age of ~ 10 weeks.
The studies reported in the present study demonstrate that Slc6a14 plays an important role in promoting the development and growth of
PyMT - driven and Neu - driven mammary tumours in
mice.
(A) Demonstration of Slc6a14 mRNA up - regulation in
PyMT - driven mammary tumours in
mice; N, mammary tissue from wild - type
mice; T, mammary tumour tissue from
PyMT - Tg
mice.
We then assessed the consequences of Slc6a14 deletion on
PyMT - driven breast cancer in these
mice.
However, when crossed with
PyMT - Tg
mice or MMTV / Neu (
mouse mammary tumour virus promoter - Neu)- Tg
mice, the development and progression of breast cancer were markedly decreased on Slc6a14 − / − background.
We examined the expression of Slc6a14 in breast tumours obtained from 4 - month - old
PyMT - Tg female
mice and in mammary glands obtained from age - matched wild - type female
mice.
Therefore, we expected that
PyMT - driven mammary tumours in Slc6a14 − / −
mice would exhibit a decrease in cell proliferation, mTOR signalling and HIF1α.
PyMT - Tg
mice develop breast cancer spontaneously at ~ 10 weeks of age [19].
In 4 - month - old
PyMT - Slc6a14 + / +
mice, metastatic nodules were detectable in the lung but there was no metastasis in age - matched
PyMT - Slc6a14 − / −
mice (Figure 2B).
In contrast, no Slc6a14 − / − female with
PyMT transgene developed tumours at 3 months of age; however, at 4 months of age, small tumour nodules became detectable (Figure 2B), indicating a marked delay in mammary tumour development in
PyMT - Tg
mice as a consequence of Slc6a14 deletion.