Role of Microtubule-Associated Protein 1b in Urothelial Carcinoma: Overexpression Predicts Poor Prognosis

Tsu-Ming Chien^{1

2

3}, Ti-Chun Chan^{4

5}, Steven Kuan-Hua Huang⁶, Bi-Wen Yeh^{3

5}, Wei-Ming Li^{1

2

3

7}, Chun-Nung Huang^{2

3}, Ching-Chia Li^{1

2

3

8}, Wen-Jeng Wu^{1

2

3

8

9

10}, Chien-Feng Li^{4

5

11

12

13}

Affiliations

¹ Graduate Institute of Clinical Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
² Department of Urology, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan.
³ Department of Urology, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
⁴ Institute of Biomedical Science, National Sun Yat-sen University, Kaohsiung 80424, Taiwan.
⁵ Department of Pathology, Chi Mei Medical Center, Tainan 710, Taiwan.
⁶ Department of Urology, Chi Mei Medical Center, Tainan 710, Taiwan.
⁷ Department of Urology, Ministry of Health and Welfare Pingtung Hospital, Pingtung 900, Taiwan.
⁸ Department of Urology, Kaohsiung Municipal Ta-Tung Hospital, Kaohsiung 801, Taiwan.
⁹ Center for Infectious Disease and Cancer Research, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
¹⁰ Center for Stem Cell Research, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
¹¹ Institute of Medical Science and Technology, National Sun Yat-sen University, Kaohsiung 80424, Taiwan.
¹² Department of Biotechnology, Southern Taiwan University of Science and Technology, Tainan 71005, Taiwan.
¹³ National Cancer Research Institute, National Health Research Institutes, Tainan 70456, Taiwan.

PMID: 32182788
PMCID: PMC7139768
DOI: 10.3390/cancers12030630

Role of Microtubule-Associated Protein 1b in Urothelial Carcinoma: Overexpression Predicts Poor Prognosis

Tsu-Ming Chien et al. Cancers (Basel). 2020.

. 2020 Mar 9;12(3):630.

doi: 10.3390/cancers12030630.

Authors

Affiliations

¹ Graduate Institute of Clinical Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
² Department of Urology, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan.
³ Department of Urology, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
⁴ Institute of Biomedical Science, National Sun Yat-sen University, Kaohsiung 80424, Taiwan.
⁵ Department of Pathology, Chi Mei Medical Center, Tainan 710, Taiwan.
⁶ Department of Urology, Chi Mei Medical Center, Tainan 710, Taiwan.
⁷ Department of Urology, Ministry of Health and Welfare Pingtung Hospital, Pingtung 900, Taiwan.
⁸ Department of Urology, Kaohsiung Municipal Ta-Tung Hospital, Kaohsiung 801, Taiwan.
⁹ Center for Infectious Disease and Cancer Research, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
¹⁰ Center for Stem Cell Research, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
¹¹ Institute of Medical Science and Technology, National Sun Yat-sen University, Kaohsiung 80424, Taiwan.
¹² Department of Biotechnology, Southern Taiwan University of Science and Technology, Tainan 71005, Taiwan.
¹³ National Cancer Research Institute, National Health Research Institutes, Tainan 70456, Taiwan.

PMID: 32182788
PMCID: PMC7139768
DOI: 10.3390/cancers12030630

Abstract

We sought to examine the relationship between microtubule-associated proteins (MAPs) and the prognosis of urothelial carcinoma by assessing the microtubule bundle formation genes using a reappraisal transcriptome dataset of urothelial carcinoma (GSE31684). The result revealed that microtubule-associated protein 1b (MAP1B) is the most significant upregulated gene related to cancer progression. Real-time reverse-transcription polymerase chain reaction was used to measure MAP1B transcription levels in urothelial carcinoma of the upper tract (UTUC) and the bladder (UBUC). Immunohistochemistry was conducted to detect MAP1B protein expression in 340 UTUC and 295 UBUC cases. Correlations of MAP1B expression with clinicopathological status, disease-specific survival, and metastasis-free survival were completed. To assess the oncogenic functions of MAP1B, the RTCC1 and J82 cell lines were stably silenced against their endogenous MAP1B expression. Study findings indicated that MAP1B overexpression was associated with adverse clinical features and could independently predict unfavorable prognostic effects, indicating its theranostic value in urothelial carcinoma.

Keywords: MAP1B; microtubule; prognosis; transcriptome; urothelial carcinoma.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

**Figure 1**
Analysis of gene expression in urinary bladder urothelial carcinoma (UBUC) using a published transcriptome dataset (GSE31684). (A) Cluster analysis of genes focusing on the GO microtubule bundle formation class (GO:0001578) revealed that *MAP1B* was one of the most significantly upregulated genes associated with more advanced pT status and metastatic disease. Tissue specimens from cancers with a distinct pT status are illustrated at the top of the heat map, and the expression levels of upregulated and downregulated genes are represented as a continuum of brightness of red or green, respectively. Specimens with no change in messenger RNA (mRNA) expression are shown in black. (B) Kaplan–Meier plots showing the prognostic significance of *MAP1B* expression for the survival of UBUC. Using a QuantiGene assay, *MAP1B* mRNA expression was significantly increased in both (C) upper tract urothelial carcinoma (UTUC) and (D) UBUC at advanced primary pT stages.

**Figure 2**
Representative sections of *MAP1B* immunostaining. Note the stepwise increments in *MAP1B* immunoreactivity from the nontumoral urothelial epithelium (inlet) and (A) noninvasive papillary UCs to (B) non–muscle-invasive (pT1), and (C) muscle-invasive (pT2–pT4) UCs. A comparison of mitotic activity showed significantly higher mitotic rates in (D) UTUC and (E) UBUC cells with increased *MAP1B* expression than in cells with low expression.

**Figure 3**
Kaplan–Meier survival analysis showing the prognostic significance of MAP1B expression for the DSS and MFS outcomes of UTUC (A and B) and UBUC (C and D).

**Figure 4**
*MAP1B* expression promotes the growth of UC cells in vitro. (A) As compared with RT4 cells, endogenous *MAP1B* mRNA (upper) and protein (lower) expressions were increased in cells from the J82 and RTCC1 cell lines. (B) The two cell lines with high endogenous *MAP1B* expression were stably silenced against *MAP1B* expression by a lentiviral vector bearing one of the two clones of *MAP1B* shRNA with different sequences for both RTCC1 (left panel) and J82 (right panel) cells. Using an ELISA-based colorimetric assay to assess the rate of BrdU uptake, cell proliferation was significantly reduced in stable *MAP1B*-knockdown (C1) RTCC1 and (C2) J82 cell lines compared with that in the corresponding shLacZ controls. Similar trends were found for cell migration and invasion among cells from the (C3 and C5) RTCC1 and (C4 and C6) J82 cell lines. (* p<0.05). More details of western blot, please view at the supplementary materials.

**Figure 5**
Stable *MAP1B* knockdown increases the sub-G1 population with significantly altered cell-cycle progression. Cell-cycle analysis as conducted by flow cytometry identified a remarkable increment of sub-G1 population indicating cell death in *MAP1B*-knockdown RTCC1 (upper panel) and J82 (lower panel) cells.

**Figure 6**
*MAP1B* knockdown induces apoptosis. Flow cytometric analysis of annexin V/propidium iodide-stained RTCC1 (upper panel) and J82 (lower panel) cell lines disclosed *MAP1B* knockdown significantly increased percentage of apoptosis. (* p < 0.05).

**Figure 7**
Stable *MAP1B* knockdown increased vinblastine-induced apoptosis. Flow cytometric analysis of vinblastine-treated RTCC1 (upper panel) and J82 (lower panel) cell lines disclosed that *MAP1B* knockdown significantly increased the sub-G1 population, indicating induced cell apoptosis.

**Figure 8**
Stable *MAP1B* knockdown increase vinblastine-induced apoptosis. Flow cytometric analysis of annexin V/propidium iodide-stained RTCC1 (upper panel) and J82 (lower panel) cell lines demonstrated *MAP1B* knockdown significantly increased percentage of vinblastine-induced apoptosis. (* p < 0.05).

**Figure 9**
Kaplan–Meier survival analysis of *MAP1B* expression for the DFS of the UBUC patient cohort receiving adjuvant chemotherapy. Kaplan–Meier survival analysis showing the prognostic significance of *MAP1B* expression for the DFS of the UBUC patient cohort receiving adjuvant chemotherapy.

See this image and copyright information in PMC

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Role of Microtubule-Associated Protein 1b in Urothelial Carcinoma: Overexpression Predicts Poor Prognosis

Affiliations

Role of Microtubule-Associated Protein 1b in Urothelial Carcinoma: Overexpression Predicts Poor Prognosis

Authors

Affiliations

Abstract

Conflict of interest statement

Figures

References

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